Relevant bibliographies by topics / Biochemical Investigations

Academic literature on the topic 'Biochemical Investigations'

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Published: 6 September 2023

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Journal articles on the topic "Biochemical Investigations"

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Jungner, Ingmar, and Ben Laurent. "XI. Biochemical Laboratory Investigations." Acta Medica Scandinavica 154, S316 (April 24, 2009): 71–79. http://dx.doi.org/10.1111/j.0954-6820.1956.tb06261.x.

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Dreyer, M. J., P. G. Chaushev, and R. F. Gledhill. "Biochemical Investigations in Geophagia." Journal of the Royal Society of Medicine 97, no. 1 (January 2004): 48. http://dx.doi.org/10.1177/014107680409700125.

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Dreyer, M. J., P. G. Chaushev, and R. F. Gledhill. "Biochemical investigations in geophagia." JRSM 97, no. 1 (December 31, 2003): 48. http://dx.doi.org/10.1258/jrsm.97.1.48.

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KAUFFMANN, F. "ON BIOCHEMICAL INVESTIGATIONS OF ENTEROBACTERIACEAE." Acta Pathologica Microbiologica Scandinavica 39, no. 2 (August 18, 2009): 85–93. http://dx.doi.org/10.1111/j.1699-0463.1956.tb03379.x.

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Bronzetti, G., E. Morichetti, C. Della Croce, R. Del Carratryore, L. Giromini, and A. Galli. "Vanadium: genetical and biochemical investigations." Mutagenesis 5, no. 3 (1990): 293–96. http://dx.doi.org/10.1093/mutage/5.3.293.

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Palmiere, Cristian, and Patrice Mangin. "Hyperthermia and postmortem biochemical investigations." International Journal of Legal Medicine 127, no. 1 (June 5, 2012): 93–102. http://dx.doi.org/10.1007/s00414-012-0722-6.

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Gurgas, L., N. D. Popescu, L. T. Hangan, S. Chirila, and Natalia Rosoiu. "The Evolution of Biochemical Indices After Basal Cell Epithelioma Removal - Case Report." ARS Medica Tomitana 23, no. 2 (May 24, 2017): 99–104. http://dx.doi.org/10.1515/arsm-2017-0018.

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Abstract The paper proposes new exposure data on etiopathogenesis basal cell epithelioma and present a clinical case investigated dermatoscopic, biochemically, treated surgically and guided to avoid relapses. The case presented is part of typical cases of pigmented basal cell carcinoma. Biochemical and haematological investigations performed one day before the excisional intervention (results 1) and 30 days (results 2) after the intervention: It is recommended to monitor biochemical investigations in which alterations were found, and ways for raising the immunological status.
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Simoons-Smit, A. M., A. M. J. J. Verweij-van Vught, I. Y. R. Kanis, and D. M. Maclaren. "Biochemical and serological investigations on clinical isolates of klebsiella." Journal of Hygiene 95, no. 2 (October 1985): 265–76. http://dx.doi.org/10.1017/s0022172400062690.

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SUMMARYA series of 925 clinical isolates of klebsiella was examined by serological and biochemical typing. To perform serological typing (capsular swelling) 77 capsular antisera were prepared, tested against the type strains and grouped in 13 pools. With this serotyping method 80% of the cultures were typable and 63 distinct types could be recognized.All strains were typable biochemically by means of the numerical coding system of the API-20E system supplemented by digits derived from 15 additional conventional biochemical tests. With the API-20E system 24 different biotypes could be distinguished whereas the combination of API-20E and the 15 additional tests produced 93 biotypes. Maximum discrimination of strains was achieved by the combination of serological and biochemical typing (256 bioserotypes). The reproducibility, typability and discriminating power of the biotyping system was not inferior to serotyping. For epidemiological purposes biotyping can replace serotyping ofKlebsiellaspecies, especially in laboratories less well equipped.
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Green, Alison. "Biochemical investigations in patients with dementia." Annals of Clinical Biochemistry: International Journal of Laboratory Medicine 39, no. 3 (May 1, 2002): 211–20. http://dx.doi.org/10.1258/0004563021902143.

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The recent development of acetylcholinesterase inhibitors to treat patients with Alzheimer's disease has increased interest in the use of biochemical markers for the early detection and diagnosis of dementia, but only the measurement of the protein 14-3-3 in cerebrospinal fluid (CSF) to help diagnose sporadic Creutzfeldt-Jakob disease has become accepted clinical practice. CSF concentrations of t protein and β-amyloid peptide 42 have been widely investigated as potential diagnostic tests for Alzheimer's disease, but neither has shown sufficient sensitivity and specificity for clinical use. Preliminary investigations suggest that β-amyloid peptide 42 may be useful in monitoring disease progression, but this needs to be verified. In addition, biochemical investigations may help to identify the small number of patients with treatable causes of dementia such as hypothyroidism and vitamin B12 deficiency, as well as any other compounding condition such as anaemia or diabetes mellitus that increase morbidity.
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Samuell, C. T., and G. P. Kasidas. "Biochemical Investigations in Renal Stone Formers." Annals of Clinical Biochemistry: International Journal of Laboratory Medicine 32, no. 2 (March 1995): 112–22. http://dx.doi.org/10.1177/000456329503200202.

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Dissertations / Theses on the topic "Biochemical Investigations"

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Patel, Vinood Bhagwandas. "Biochemical investigations into experimental alcoholic cardiomyopathy and hypertension." Thesis, King's College London (University of London), 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266477.

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Taylor, Claire Louise. "Biochemical investigations of defects of the mitochondrial respiratory chain." Thesis, University of Newcastle Upon Tyne, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.281706.

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Shnoudeh, Abeer Jabra. "Biochemical and biophysical investigations of novel phosphodiesterase-5 inhibitors." Thesis, King's College London (University of London), 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.429578.

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Harrison, Peter J. "Biochemical investigations of the carotenoid cleavage dioxygenase enzyme family." Thesis, University of Warwick, 2014. http://wrap.warwick.ac.uk/66554/.

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The biosynthesis of the plant hormones strigolactone and abscisic acid is, in part, controlled by a family of enzymes known as the carotenoid cleavage dioxygenases (CCDs), which perform an oxidative cleavage reaction on a carotenoid substrate (9’-cis-neoxanthin for abscisic acid and 9-cis-β-carotene and 9-cis-β-apo-10’-carotenal for strigolactone) to form apocarotenoids, which are metabolised to the functional phytohormone. Phenotypic effects on seed dormancy and shoot branching have been observed in Arabidopsis thaliana and Zea mays on the application of a selection of hydroxamic acids based inhibitors, designed to inhibit CCDs, whereby application of the inhibitor to the plant result in a decrease in the time take for germination (abscisic acid mediated) or an increase in the number of lateral shoot branches (strigolactone mediated). However, the biochemical basis of these phenotypes is not understood. In the present thesis, carotenoid cleavage dioxygenases from the abscisic acid biosynthesis pathway (9’-cis-epoxycarotenoid cleavage dioxygenases (NCED)) and strigolactone biosynthesis pathway (CCD7 and CCD8) were produced in vitro and assayed for inhibition against the hydroxamic acid inhibitors. The results show that Z. mays NCED is indeed inhibited by the hydroxamic acid inhibitors (D2: greater than 95% inhibition at 100 μM) in a time dependent fashion, indicating that inhibition of NCED is the basis of the seed germination phenotype. On the strigolactone biosynthesis pathway, recombinant A. thaliana CCD7 is not inhibited by the hydroxamic acids. However, recombinant A. thaliana CCD8 is inhibited by hydroxamic acids that show shoot branching phenotypes (D6 53% inhibition at 10 μM), suggesting that inhibition of CCD8 is the basis of the shoot branching phenotype. Structure activity relationships have also been performed to identify the key features of the hydroxamic acids required to inhibit each enzyme. The biochemistry of several CCDs has also been investigated, along with that of the enzyme Dwarf27, an isomerase enzyme required for the isomerisation of all-trans-β-carotene to 9-cis-β-carotene on the strigolactone biosynthesis pathway. Investigations indicate that Dwarf27 from Oryza sativa could be a novel iron-sulfur protein which isomerises β-carotene via a one electron transfer to or from the β-carotene substrate. D27 is also inhibited to some extent by certain hydroxamic acids (e.g. 41% by D30 at 100 μM). Biochemical characterisation of A. thaliana CCD8 provides evidence for a two-step mechanism involving acid-base catalysis, and evidence is obtained for an active site cysteine residue. A possible mechanism for the double oxidative cleavage reaction catalysed by CCD8 is proposed. These results provide an insight into the biochemistry of the biosynthesis of the phytohormones abscisic acid and strigolactone and demonstrate that enzymes on the biosynthesis pathways of these hormones can be selectively inhibited using a chemical genetics approach. This has potential to aid the development of novel agrochemical compounds which could influence these processes to improve plant architecture and crop yield.
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Haggarty-Weir, Christopher Neil. "Biochemical and biophysical investigations into key malaria parasite proteins." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/29617.

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Plasmodium falciparum, the most pestilential of the malaria parasite species, is responsible for ~450,000 direct deaths annually. Clinical disease is a consequence of the blood stage of the parasite’s lifecycle involving a plethora of host-parasite interactions. Key to these interactions are the P. falciparum reticulocyte binding-like homologue (PfRh) proteins responsible for binding erythrocyte receptors and gaining entry to host cells. For example, PfRh4 binds to human complement receptor-1 (CR1) on erythrocytes for sialic-acid-independent invasion. Another protein important for invasion is the PfRh5-interacting protein (PfRipr), an essential member of the PfRh5-associated invasion complex (PAIN-complex) along with CyRPA, the cysteine-rich protective antigen. Loss of function of PfRipr in P. falciparum parasites prevents erythrocyte entry and ablates Ca2+-influx into the erythrocyte; essential events during invasion. This study aimed to biochemically and structurally investigate truncated recombinant versions of PfRh4 and PfRipr. Homology modelling suggested that PfRh4 is rich in alpha-helical secondary structure. The sequence of PfRipr suggested the presence of ten epidermal growth factor-like (EGF) modules, two towards the N-terminus and eight in the C-terminal domain. In this project, monoclonal antibodies made against recombinant PfRh4 were shown, via indirect immunofluorescent assays, to localize to the apical tip of merozoites. Monoclonal antibody 5H12, raised against PfRh4, reduces parasite invasion of erythrocytes by ~75% in growth-inhibition assays with neuraminidase pre-treated erythrocytes. Attempts to produce a stable truncated recombinant PfRh4 protein for structural studies were unsuccessful. An ELISA-based assay using ten alanine-scan mutants suggested the CR1-binding site lies outside of amino acids 283 – 341 of PfRh4. PfRipr truncations, defined by the boundaries of EGF-like repeats predicted based on sequence homology, were produced recombinantly in Escherichia coli and Pichia pastoris. These proteins had a circular dichroism signature suggestive of β-strand-containing proteins with disordered regions. EGF-containing PfRipr truncations did not bind recombinant PfRh5 according to ELISA and size-exclusion chromatography assays. EGFs 1-2, 5-7 and 7-10 of PfRipr did not bind CyRPA via size-exclusion chromatography or NMR. Crystallisation trials performed on EGF modules failed to yield crystals suitable for data collection. A 15N isotopically-labelled sample of EGF5-7 gave good quality HSQC NMR spectra. A suite of three-dimensional NMR spectra collected on a 13C,15N-EGF5-7 sample, at three different temperatures, allowed for >86% of backbone assignments. T1/T2 relaxation analysis and heteronuclear NOE data were suggestive of an elongated, rigid protein undergoing intermolecular self-association. Further evidence for EGF5-7 being an elongated protein was provided via SAXS analysis. Chemical shifts facilitated prediction of secondary structure in EGF 5-7 consistent with an EGF-like fold. Melting studies performed on EGF5-7 showed no evidence of denaturation over the temperature range 20 °C - 95 °C indicating a thermally-stable protein. The addition of Ca2+ to the 15N-EGF5-7 sample caused chemical shift perturbations consistent with high-affinity binding. The discovery of inhibitory monoclonal antibodies recognising a conformational epitope on EGF7 provided evidence of the functional importance of this region within PfRipr. The work described in this thesis provides methods for the industrially-scalable production and biophysical investigations of P. pastoris or E. coli-produced disulfide-rich P. falciparum antigens of interest to vaccinologists.
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Berrisford, John Mark. "Biochemical and structural investigations on phosphoglucose isomerase from Pyrococcus furiosus." Thesis, University of Sheffield, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434961.

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Konrad, Josef. "In vitro culture of Babesia divergens : biochemical and immunological investigations." Thesis, Imperial College London, 1986. http://hdl.handle.net/10044/1/38073.

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Lee, Jenny Swee Chin. "Biochemical and physiological investigations of Brassica oleracea var. botrytis L." Thesis, University of Bath, 1985. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355378.

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The curds of cauliflower (Brassica oleracea var.botrytis L.) which are representative of the European biennials, European annuals and Australian types were used to extract aspartate aminotransferase (EC 2.6.1.1) and acid phosphatase (EC 3.1.3.2). These enzymes were separated into their isoenzymes using polyacrylamide gel electrophoresis and were shown to have different numbers of isoenzymes depending upon which of the three main groups of cauliflower cultivars were used. The enzymes examined showed evolutionary divergence of the cauliflower types. Growth and development, storage and frost damage in cauliflowers were examined in relation to peroxidase activity. Physiological age in different parts of the curds and between different size curds was shown to have very little effect on peroxidase activity. Total peroxidase activity in the stem was about 2 times the value in the curds. A gradual increase of peroxidase was found to occur with duration of storage period at 7°C. Peroxidase activity remained low when cauliflowers were kept at low temperatures, namely both -1 + 1°C and -5 + 1°C, but increased rapidly on warming up at 7°C for 2 days. Isolation and partial purification of the peroxidase were carried out using conventional methods, including ammonium sulphate precipitation, Sephadex G-100 molecular sieve and DEAE Cellulose ion exchange chromatography. Further purification was achieved using Phenyl Sepharose hydrophobic interaction chromatography. Peroxidase activity was localized in the 50-95% ammonium sulphate precipitation. Molecular sieve chromatography showed a broad peak of peroxidase activity and molecular weight was estimated to be about 42,000. Polyacrylamide gel electrophoresis and isoelectric focusing of this fraction showed the existence of two peroxidase isoenzymes with P 6.7 and 7.3 using guaiacol as substrate; one of the isoenzymes also possessed a simultaneous IAA oxidase activity. Optimal pH and temperature with guaiacol as a substrate was found to be pH 5.6 and 50°C. Kinetic studies indicated an apparent Km of 8.3 mM for guaiacol at an optimal hydrogen peroxide concentration and a Km of 6.25 mM for hydrogen peroxide at an optimal guaiacol concentration. By including hydrophobic interaction chromatography in the purification scheme, a homogeneous cauliflower peroxidase isoenzyme was obtained. It showed as a single band in polyacrylamide gel electrophoresis and sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Molecular weight estimation of this peroxidase isoenzyme was 41,000+1,000. The elution profiles of white and green cauliflowers and white sprouting broccoli peroxidases by hydrophobic interaction chromatography were found to be different. Green cauliflowers with high frost resistance were found to have high percentage of peroxidase activity bound very tightly to the hydrophobic resin. Similar peroxidase activity patterns using guaiacol, o-dianisidine and pyrogallol were obtained. Antiserum specific for the homogeneous peroxidase from cauliflower (cv. Milreef) was used to examine homology among cauliflower peroxidases and among peroxidases from green and white cauliflowers, white sprouting broccoli and horseradish. The antiserum cross reacted with all cauliflower peroxidases as well as peroxidases from green cauliflower, white sprouting broccoli and horseradish, indicating the antigenic sites were similar.
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Coates, Christopher J. "Hemocyanin-derived phenoloxidase : biochemical and cellular investigations of innate immunity." Thesis, University of Stirling, 2012. http://hdl.handle.net/1893/12228.

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Hemocyanins (Hcs) and phenoloxidases (POs) are both members of the type-3 copper protein family, possessing di-cupric active sites which facilitate the binding of dioxygen. While Hcs and POs share a high degree of sequence homology, Hcs have been associated traditionally with oxygen transport whereas POs are catalytic proteins with a role in innate immunity. Evidence gathered in recent years details numerous immune functions for Hc, including an inducible PO activity. Unlike the pro-phenoloxidase activation cascade in arthropods, the endogenous mechanism(s) involved in the conversion of Hc into an immune enzyme is lacking in detail. The overall aim of this research was to characterise the physiological circumstances in which Hc is converted into a PO-like enzyme during immune challenge. A series of biochemical, biophysical and cellular techniques were used to assess the ability of phospholipid liposomes to mimic the well-characterised induction of PO activity in Hc by SDS micelles. Incubation of Hc purified from Limulus polyphemus, in the presence of phosphatidylserine (PS) liposomes, yielded ~ 90% of the PO activity observed upon incubation of Hc with the non-physiological activator, SDS. Phospholipid–induced PO activity in Hc was accompanied by secondary and tertiary structural changes similar to those observed in the presence of SDS. Subsequent analysis revealed that electrostatic interactions appear to be important in the PS-Hc activation complex. In vivo, PS-Hc interactions are assumed to be limited in quiescent cells. However, amebocytes undergoing apoptosis redistribute PS onto the outer leaflet of the plasma membrane, resulting in the potential for increased Hc-PS interactions. In the absence of a reliable culturing technique for L. polyphemus amebocytes, in vitro conditions were optimised for the short term maintenance of this labile cell type. Amebocytes retained viability and functionality in a medium that mimicked most-closely, the biochemical properties of L. polyphemus hemolymph. When presented with a fungal, bacterial or synthetic challenge, ~9% of amebocytes in vitro were found to be phagocytically active. Target internalisation was confirmed via the use of fluorescent quenchers and membrane probes. Within 4 hours of target internalisation, amebocytes underwent apoptosis, characterised by the loss of plasma and mitochondrial membrane potential, increased caspase-3 activity and extracellularisation of PS. Phagocytosis-induced cell death led to a proportional increase in the level of Hc-derived PO activity, suggesting that Hc may be interacting with PS present on terminal amebocyte membranes. The PO activity of Hc was investigated further in order to address an economically important issue; hyperpigmentation in commercial shellfish. While PO enzymes are thought to be the cause of hyperpigmentation in Nephrops norvegicus, evidence presented here suggests that cellular PO is inactivated after freeze-thawing, while extracellular Hc retains stability and displays a heightened level of inducible PO activity under similar treatments. Known PO inhibitors were used successfully to reduce Hc-derived PO activity, with inhibitors assumed to bind Hc in a manner similar to PO-inhibitor complexes. Structural and functional studies of hemocyanins and immune cells presented here provide new insights into the interactions of hemocyanin-activator complexes in invertebrates.
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Tormey, William Patrick. "The provision of biochemical investigations in forensic toxicology for coroners." Thesis, Ulster University, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.646399.

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Death certification plays a central role in health service planning therefore identification of specific causes of death is critical. The requirements of biochemical toxicology as set out in the Coroners Acts in Ireland, Northern Ireland and England and Wales will be parsed to facilitate the construction of a modern best practice template for coroners' toxicology. The Royal College of Pathologists (RCPath) provides published standard guidelines for pathologists reporting to coroners. Their adequacy will be critically evaluated to facilitate reform with the intention of maximising the accuracy of death certification. The roles of psychological factors, tobacco smoking, non steroidal anti-inflammatory drugs, and cannabis in cardiac death will be detailed. The potential for adverse drug reactions to prescription medication to cause death by misadventure will be explored. The role for the expert witness in the inquisitorial coroners system to improve the accuracy of the causes of death and thus the verdict will be explored. My experience has shown that misinterpretation of presence of cannabis in autopsy blood and urine samples is common and this underlines the need for true expert guidance for the coroner. The current practice in biochemical toxicology of screening blood, urine and vitreous humor will be critically evaluated and the necessity for a wide ranging screen of potential toxins as a contributor to the cause of death examined. The appropriate analytes on the screening menu will be determined by local cultural factors. Gas and liquid chromatography with mass spectrometry are the methods of choice. The interpretation of isopropanol, ethanol and ketones in post-mortem blood will be considered as will t~e role of alcohol in death. The apparent population exposure to poisons as reported by Poisons Information Services will be used to explore the dichotomy between the usually benign outcome of common poisons and the often lethal consequences of poisoning by prescription and illicit drugs. The aim of this research is to use the template of the current legal requirements and routine laboratory procedures to suggest reforms which will improve the analytical protocol and reporting of biochemical toxicology in the coronial system resulting in greater accuracy in delineating the causes of death The narrative of this thesis travels through the areas of the coroners acts especially in the Republic of Ireland and the United Kingdom where forensic biochemistry plays a role in the specification of the causes of deaths. There is a deconstruction of the place of doctors in the coronial system and in the new arrangements following the passage of the Coroners and Justice Act 2009 in England and Wales and the potential for change in the Coroners Bill in the Republic of Ireland which fell with the dissolution of the Dail in20ll. There is an examination of the autopsy guidelines issued by the RCPath and suggestions for change which have been published. There is an analysis of the place of cannabinoids in coroners ' cases and publications setting out the position are included. A series of recommendations are made regarding improvement in practice for the reporting of biochemical toxicology in the coronial system. Two cases where there appears to be potential misinterpretation of the toxicological evidence, which may result in the review of the causes of death, are detailed as relevant clinical examples. Some laboratory pitfalls in relation to alcohol analysis have been demonstrated and the consequences of a protocol free service have been detailed with a prescription for improvement and practical solutions to improve outcomes. The under-estimation of the impact of tobacco toxicity is also addressed as is the potential for error due to lack of appreciation of drug-drug interactions. The role of biochemistry in the post-mortem diagnosis of alcoholic and diabetic ketoacidosis is discussed. Multidisciplinary reviews of biochemical toxicology for the coroners' court are suggested as the best safeguard of accurate interpretation to assist coronial enquiry. Conclusions suggesting standard operating procedures for post-mortem scenarios are detailed where possible.
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Books on the topic "Biochemical Investigations"

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Fahl, Kirsten. Biochemische Untersuchungen zum Lipidstoffwechsel antarktischer Copepoden =: Biochemical investigations on the lipidmetabolism of Antarctic copepods. Bremerhaven: Alfred-Wegener-Institut für Polar- und Meeresforschung, 1995.

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Silverman, Eric. Methodological Investigations in Agent-Based Modelling: With Applications for the Social Sciences. Cham: Springer Nature, 2018.

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Stål, Per. Characterization of human oro-facial and masticatory muscles with respect to fibre types, myosins and capillaries: Morphological, enzyme-hisotchemical, immuno-histochemical and biochemical investigations. Umeå, Sweden: Departments of Anatomy and Clinical Oral Physiology, Umeå University, 1994.

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Cualain, Ronan Ó. Biochemical investigation of scorpion venom. [S.l: The Author], 2003.

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United Planters' Association of Southern India. Tea Research Institute., ed. Project final report on investigations on the biochemical basis of rooting and clonal compatibility in nursery grafting of fresh cuttings in tea (camellia l. spp.). Valparai: The Institute, 1996.

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Tinaztepe, Sedef. Biochemical and Genetic Investigation of Immature Murine Leukemia Virus Assembly. [New York, N.Y.?]: [publisher not identified], 2017.

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Bruton, Rachel Kathlyn. An immunological and biochemical investigation of some cental metabotropic glutamate receptors (mGluRs). Birmingham: University of Birmingham, 1996.

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Collins, Karen. The investigation of B-NAG as a biochemical marker of early diabetic nephropathy. [S.l: The Author], 1993.

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Huengsberg, Mia. Investigation of biochemical abnormalities in HIV associated neurological diseases - a prospective and retrospective study. Birmingham: University of Birmingham, 1998.

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Blackwell, Malcolm Peter. Investigation of a biochemical marker of pulmonary eosinophil influx as a predictive assay for low molecular weight respiratory sensitisers. [Derby: University of Derby], 1999.

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Book chapters on the topic "Biochemical Investigations"

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Nyström, Ernst, Gertrud E. B. Berg, Svante K. G. Jansson, Ove Tørring, and Stig V. Valdemarsson. "Biochemical Investigations." In Thyroid Disease in Adults, 29–45. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-13262-9_3.

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Phillips, William J., and Richard A. Cerione. "Fluorescence Investigations of Receptor-Mediated Processes." In Biophysical and Biochemical Aspects of Fluorescence Spectroscopy, 135–67. Boston, MA: Springer US, 1991. http://dx.doi.org/10.1007/978-1-4757-9513-4_5.

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McIntyre, N., and S. Rosalki. "Biochemical Investigations in the Management of Liver Disease." In Hepatobiliary Diseases, 39–71. Berlin, Heidelberg: Springer Berlin Heidelberg, 1992. http://dx.doi.org/10.1007/978-3-642-76802-6_2.

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Fouquet, Guillemette, Stéphanie Poulain, Suzanna Schraen, Efstathios Koulieris, Elisabeth Bertrand, Stéphanie Guidez, Cécile Tomowiak, et al. "Laboratory Investigations and Findings: Hematological Abnormalities, Biochemical Investigations, Free Light and Heavy Chains." In Waldenström’s Macroglobulinemia, 239–61. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-22584-5_17.

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Bushueva, N. N. "Results of Biochemical Investigations of Congenital Myopia in Children." In Myopia Updates, 118. Tokyo: Springer Japan, 1998. http://dx.doi.org/10.1007/978-4-431-66959-3_24.

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Tollnick, C., G. Seidel, M. Beyer, and K. Schügerl. "Investigations of the Production of Cephalosporin C by Acremonium chrysogenum." In New Trends and Developments in Biochemical Engineering, 1–45. Berlin, Heidelberg: Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/b12439.

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Marsac, C., F. Degoul, D. Francois, N. B. Romero, M. Fardeau, P. Lestienne, I. Nelson, and J. L. Vayssiere. "Biochemical and genetic investigations in eleven cases of mitochondrial myopathies." In Molecular Basis of Neurological Disorders and Their Treatment, 221–27. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3114-8_21.

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Delbrück, A., and H. Schröder. "Fibroblast Gel Culture: A Model for Biochemical Investigations of Dupuytren’s Contracture." In Dupuytren’s Disease, 111–16. Berlin, Heidelberg: Springer Berlin Heidelberg, 1994. http://dx.doi.org/10.1007/978-3-642-78517-7_12.

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Albus, Margot. "Biochemical and Clinical Investigations with Regard to Plus and Minus Symptomatology in Schizophrenia." In Clinical Psychopathology Nomenclature and Classification, 441–47. Boston, MA: Springer US, 1985. http://dx.doi.org/10.1007/978-1-4899-5049-9_78.

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Sellami, Badreddine, Imen Bouzidi, Wiem Saidani, Amine Mezni, David Sheehan, and Hamouda Beyrem. "Effects of Gold Nanoparticles on the Mediterranean Clams Ruditapes decussatus: Chemical and Biochemical Investigations." In Recent Advances in Environmental Science from the Euro-Mediterranean and Surrounding Regions, 577–80. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-70548-4_174.

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Conference papers on the topic "Biochemical Investigations"

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Aubry, André. "The pseudopeptides as structural tools for biochemical investigations." In VIIth Conference Biologically Active Peptides. Prague: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 2001. http://dx.doi.org/10.1135/css200104020.

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Delipovici, Irina. "Dinamica indicilor biochimici în efort muscular." In Congresul Ştiinţific Internaţional "Sport. Olimpism. Sănătate". State University of Physical Education and Sport, Republic of Moldova, 2022. http://dx.doi.org/10.52449/soh22.13.

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The knowledge of biochemical processes that appear during a physical effort, actually, has a major importance for the scientific practice of sport process. The performance sport trainings are inconceivable without a biochemical control. Due to clinical and biochemical investigations, there is a potential of analyzing and control of the sports training. While planning and implementing the training program, the coach gets the possibility to analyze the efficiency, intensity and the volume of physical exertion. The trainer who in the training process is based on the results of biochemical investigations, can essentially expand the methodological possibilities of training athletes.
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Chaudhary, Nidhee, Subhash Chand, and Nameet Kaur. "Biochemical Investigations of Thermostable Acid Phosphatases from Pisum Sativum and Ttriticum Aestivum Cotyledons." In Annual International Conference on Advances in Biotechnology. Global Science and Technology Forum (GSTF), 2012. http://dx.doi.org/10.5176/2251-2489_biotech33.

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Salamon, Zdzislaw, Gordon Tollin, Angus Macleod, and Ian C. Stevenson. "Coupled plasmon-waveguide resonator for biochemical sensors." In Optical Interference Coatings. Washington, D.C.: Optica Publishing Group, 1997. http://dx.doi.org/10.1364/oic.1998.thd.3.

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The outer surface of a high-performance metal can support a propagating surface wave that decays exponentially into both the metal and the surrounding medium. P-polarized light can be coupled into such a surface wave under conditions involving a narrow range of angles of incidence beyond the critical angle and a correct thickness of metal film, readily achieved by depositing the metal film on the base of a dielectric prism. Illumination of the prism base from within achieves coupling with a surface wave on the outer surface of the metal, characterized by a deep, narrow dip in p-polarized reflectance known as a surface plasmon resonance. Because the resonance depends critically on the conditions at the outer surface of the metal, it is very sensitive to any changes there. In particular, when a very small amount of additional material is added to the metal surface, the resonance responds by moving to a greater angle of incidence and changing its shape. Measurement of these changes can then be interpreted in terms of the properties of the additional layer. Three principal parameters characterize the resonance, width, depth and angular position, and these can be related to the thickness and optical properties of the added layer. This contrasts with ellipsometric measurements that have essentially two parameters and possesses the additional advantage over these and other techniques that the measurement is completely confined to the side of the metal film remote from the film under measurement. The technique has been used in many applications but especially in biochemical investigations of membrane protein processes [1, 2].
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Szabo, Arthur G. "Laser Instrumentation And Data Analysis In Time Correlated Photon Counting Fluorescence Decay Measurements In Biochemical Investigations." In 1988 Los Angeles Symposium--O-E/LASE '88, edited by Joseph R. Lakowicz. SPIE, 1988. http://dx.doi.org/10.1117/12.945362.

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Mofrad, Mohammad R. K. "Molecular Mechanosensors and Focal Adhesion Mechanotransduction." In ASME 2010 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2010. http://dx.doi.org/10.1115/sbc2010-19707.

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Cellular response to mechanical stimulation is mediated by both biochemical mechanisms via changes in gene expression and by biophysical mechanisms via mechanically induced changes in specific molecules’ structure and function. These mechanically responsive molecules can be described as the cell’s mechanosensors and can function to initiate processes such as focal adhesion formation. A series of molecular dynamics investigations explore the mechanosensor function of key molecules involved in focal adhesion formation and cytoskeletal dynamics.
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Vickerman Kelley, Vernella V., and Roger D. Kamm. "Microfluidics Bioreactor: A Platform for Studying Capillary Morphogenesis in Response to Biochemical and Biophysical Cues." In ASME 2007 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2007. http://dx.doi.org/10.1115/sbc2007-176655.

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The in vivo microvasculature is a dynamic structure which is influenced by both biochemical (e.g. cytokines, growth factors) and biophysical factors (e.g. shear stress, interstitial flow). Important regulators of this structure are the endothelial cells which are normally quiescent but under certain conditions are able to form new vascular sprouts. Investigations into the mechanism of capillary morphogenesis of human endothelial cells warrant an in vitro model that closely mimics the physiological in vivo microenvironment. To this end, we have developed a novel microfabricated system which permits 2D and 3D culture of endothelial cells in biologically derived (e.g. type I collagen) or synthetic (self assembling peptides) scaffolds and delivers control flow rates and pressures. This system offers tremendous flexibility with regard to scaffold physical and chemical properties, physiologically relevant mechanical stress induced by surface shear and interstitial flow as well as chemotactic gradients. In addition we are able to directly monitor the progression of vascular networks in response to these critical factors.
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Shamloo, Amir, and Sarah C. Heilshorn. "The Interplay Between Biomechanical and Biochemical Factors Regulates Lumen Formation and Navigation of Endothelial Cell Sprouts." In ASME 2010 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2010. http://dx.doi.org/10.1115/sbc2010-19495.

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Angiogenesis is the process of forming new blood vessels that originate from pre-existing vessels. In early angiogenesis stages, endothelial cells (ECs) migrate from the lumen of developed blood vessels into the surrounding extracellular matrix (ECM). Through the coordinated actions of migration and proliferation, these ECs organize into tubular capillary-like structures called sprouts. In this study, 3D EC sprout formation was examined using a microfluidic device that enabled the separate and simultaneous tuning of biomechanical and biochemical stimuli (Fig. 1). While previous investigations have been performed on each of these factors individually1, 2, more recent studies have identified a critical interplay between the simultaneous effects of these two factors3. For example, we previously studied 2D EC chemotaxis in response to vascular endothelial growth factor (VEGF) gradients in the absence of biomechanical stimulation.4 In developing a model that enables precise specification of biochemical and biomechanical cues, we utilized a protocol that enables ECs to undergo a transition from the 2D to 3D culture environment mimicking angiogenic sprouting. Here we quantified the relative importance and combined consequences of discrete changes in matrix density, growth factor concentration, and growth factor gradient steepness during the stages of early sprout initiation, sprout elongation, sprout navigation, and lumen formation.
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Wurzinger, L. J., R. Opitz, and H. Schmid-Schönbein. "ULTRASTRUCTURAL INVESTIGATIONS ON THE MECHANISM OF “SHEAR-INDUCED PLATELET ACTIVATION”." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1642845.

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High shear forces are suspected to play a triggering role in the initiation of arterial thrombosis, by activating platelets and the coagulation system. In an earlier study a shear stress of 170 N/m2 acting for only 7 milliseconds (ms) on platelet rich plasma (PRP) was found to induce a significant increase in platelet factor 3 availability (Thromb. Haemost. 54: 381-386; 1985). To clarify the question whether platelets can be activated directly by mechanical forces in analogy to smooth muscle cells, electron micrographs of platelets subjected to laminar shear stress were analysed with morphometric methods. The level of activation of platelet suspensions was quantified by assessing 1) the elongation of platelet profiles giving a measure for the “flatness” of the discoid resting platelets, and 2) the centralization of granules.Exposure to a shear stress of 170 N/m2 for 113 ms leaves ca. 15 % of the platelets irreversibly damaged, featuring degenerative ballooning, with break-down of internal structure and cell membrane defects. The remaining 85 % appear typically activated with rounded shape, extension of pseudopods and centralization of granules. Addition of “ADP-scavengers” to the suspension medium totally changes the appearance of sheared platelets: still a comparable proportion of them has undergone irreversible degenerative changes, but the “surviving” population lacks ultrastructural signs of platelet activation. This is reflected in values of the morphometric parameters which are close to the level of unsheared control samples.It is therefore concluded that “shear-induced platelet activation” cannot be ascribed to a direct stimulating effect of shear forces, but rather to secondary biochemical activation by adenine nucleotides leaking from a small percentage of shear destroyed platelets. The latter process, however, requires a well stirred though undiluted environment, as it is provided in vortices and eddies.
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Matichenkov, V. "REDUCTION OF GREENHOUSE GASES EMISSION UNDER SILICON FERTILIZER APPLICATION." In Land Degradation and Desertification: Problems of Sustainable Land Management and Adaptation. LLC MAKS Press, 2020. http://dx.doi.org/10.29003/m1701.978-5-317-06490-7/165-169.

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The application of Si fertilizer is example of “green” low emission technology. The using of biochemical active forms of Si allow to reduce the greenhouse gases emission from cultivated soils, increase the carbon content in soil matrix, increase cultivated plants resistance to abiotic stresses and increase the quality and quantity of crop. Our investigations have sowed the presence of monosilicic acid in soil provide the reduction of N2O emission in 1.6-2 times because the denitrification process in such soil are complete with final formation of N2. The application of Si fertilizer increased the rice crop on 5-55% with carbon sequestration up to 15 t/ha of CO2 during one season.
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Reports on the topic "Biochemical Investigations"

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Izhar, Shamay, Maureen Hanson, and Nurit Firon. Expression of the Mitochondrial Locus Associated with Cytoplasmic Male Sterility in Petunia. United States Department of Agriculture, February 1996. http://dx.doi.org/10.32747/1996.7604933.bard.

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The main goal of the proposed research was to continue the mutual investigations into the molecular basis of CMS and male fertility restoration [MRF], with the ultimate goal of understanding these phenomena in higher plants. The experiments focused on: (1) dissecting apart the complex CMS - specific mitochondrial S-Pcf locus, in order to distinguish its essential parts which cause sterility from other parts and study its molecular evolution. (2) Studying the expression of the various regions of the S-Pcf locus in fertile and sterile lines and comparing the structure and ultrastructure of sterile and fertile tissues. (3) Determine whether alteration in respiration is genetically associated with CMS. Our mutual investigations further substantiated the association between the S-Pcf locus and CMS by the findings that the fertile phenotype of a population of unstable petunia somatic hybrids which contain the S-Pcf locus, is due to the presence of multiple muclear fertility restoration genes in this group of progenies. The information obtained by our studies indicate that homologous recombination played a major role in the molecular evolution of the S-Pcf locus and the CMS trait and in the generation of mitochondrial mutations in general. Our data suggest that the CMS cytoplasm evolved by introduction of a urs-s containing sublimon into the main mitochondrial genome via homologous recombination. We have also found that the first mutation detected so far in S-Pcf is a consequence of a homologous recombination mechanism involving part of the cox2 coding sequence. In all the cases studied by us, at the molecular level, we found that fusion of two different cells caused mitochondrial DNA recombination followed by sorting out of a specific mtDNA population or sequences. This sequence of events suggested as a mechanism for the generation of novel mitochondrial genomes and the creation of new traits. The present research also provides data concerning the expression of the recombined and complex CMS-specific S-Pcf locus as compared with the expression of additional mitochondrial proteins as well as comparative histological and ultrastructural studies of CMS and fertile Petunia. Evidence is provided for differential localization of mitochondrially encoded proteins in situ at the tissue level. The similar localization patterns of Pcf and atpA may indicate that Pcf product could interfere with the functioning of the mitochondrial ATPase in a tissue undergoing meiosis and microsporogenesis. Studies of respiration in CMS and fertile Petunia lines indicate that they differe in the partitioning of electron transport through the cytochrome oxidase and alternative oxidase pathways. The data indicate that the electron flux through the two oxidase pathways differs between mitochondria from fertile and sterile Petunia lines at certain redox states of the ubiquinone pool. In summary, extensive data concerning the CMS-specific S-Pcf locus of Petunia at the DNA and protein levels as well as information concerning different biochemical activity in CMS as compared to male fertile lines have been accumulated during the three years of this project. In addition, the involvement of the homologous recombination mechanism in the evolution of mt encoded traits is emphasized.
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Juvik, John A., Avri Bar Zur, and Torbert R. Rocheford. Breeding for Quality in Vegetable Maize Using Linked Molecular Markers. United States Department of Agriculture, January 1993. http://dx.doi.org/10.32747/1993.7568764.bard.

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Recently, the vegetable corn industry has shifted from the use of traditional cultivars with the sugary1 (su1) endosperm mutation to newer hybrids homozygous for the shrunken2 (sh2) or sugary enhancer1 (se1) genes. With greater kernel sucrose content, these hybrids are preferred by consumers and retain sugar for longer post harvest periods, providing the industry with more time to marker products with superior quality. Commercialization has been hindered, however, by reduced field emergence, and the establishment of stands with heterogeneous uniformity and maturities. This investigation was conducted to identify key biochemical and physiological characteristics in sh2 and se1 maize kernels associated with improved emergence, and stand establishment; and in immature ears at fresh harvest maturity, properties associated with eating quality. The location of genes or QTL controlling these kernel characteristics and other traits were then mapped to specific chromosomal regions by their linkage to molecular markers using two segregating F2:3 populations. This database was used to compare the efficiency of marker-assisted selection of key alleles with phenotypic selection for trait improvement. A model designed to uncover and quantify digenic interaction was applied to the datasets to evaluate the role of epistasis in the inheritance of quantitative traits.
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Laurinavichius, K. S. Experimental Investigation of Microbially Induced Corrosion of Test Samples and Effect of Self-Assembled Hydrophobic Monolayers. Exposure of Test Samples to Continuous Microbial Cultures, Chemical Analysis, and Biochemical Studies. Office of Scientific and Technical Information (OSTI), September 1998. http://dx.doi.org/10.2172/758748.

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Freeman, Stanley, and Russell J. Rodriguez. The Interaction Between Nonpathogenic Mutants of Colletotrichum and Fusarium, and the Plant Host Defense System. United States Department of Agriculture, September 2000. http://dx.doi.org/10.32747/2000.7573069.bard.

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The intent of this proposal was to study the interaction between nonpathogenic mutants of Colletotrichum magna and Fusarium oxysporum, and the cucurbit host defense system. We had shown previously that a nonpathogenic endophytic mutant path- 1 of C. magna, caused no visible disease symptoms but protected watermelon seedlings from disease caused by the wildtype isolate and F. o. niveum. Objectives were: 1) Determine the microscopic, biochemical and molecular genetic interaction between "protected" (path- 1 colonized) cucurbit hosts and wildtype isolates of C. magna; 2) Isolate non-pathogenic mutants of F.o. melonis and test feasibility for protecting plants against fungal diseases. We found that path-1 caused no visible disease symptoms in cucurbit seedlings but conferred disease resistance against pathogenic isolates of C. magna, C. orbiculare, and F. oxysporum. Disease resistance conferred by path-1 correlated to a decrease in the time of activation of host defense systems after exposure of path-1 colonized plants to virulent pathogens. This was determined by monitoring the biochemical activity of PAL and peroxidase, and the deposition of lignin. It appears that path-1-conferred disease resistance is a multigenic phenomenon which should be more difficult for pathogen to overcome than single gene conferred resistance. Based on the benefits conferred by path-1, we have defined this mutant as expressing a mutualistic lifestyle. REMI (restriction enzyme-mediated integration) nonpathogenic mutants were also isolated using pHA1.3 plasmid linearized with Hind III and transformed into wildtype C. magna. The integrated vector and flanking genomic DNA sequences in REMI mutant R1 was re-isolated and cloned resulting in a product of approximately 11 kb designated pGMR1. Transformations of wildtype C. magna with pGMR1 resulted in the same non-pathogenic phenotype. A nonpathogenic mutant of F.o. melonis (pathogenic to melon) was isolated that colonized melon plants but elicited no disease symptoms in seedlings and conferred 25 - 50% disease protection against the virulent wildtype isolate. Subsequently, nonpathogenic mutant isolates of F.o. niveum (pathogenic to watermelon) were also isolated. Their protection capacity against the respective wildtype parent is currently under investigation. This research has provided information toward a better understanding of host-parasite interactions; specifically, endophytes, pathogens and their hosts. It will also allow us to assess the potential for utilizing nonpathogenic mutants as biological control agents against fungal pathogens and isolating molecular genetic factors of pathogenicity in Fusarium.
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Woodson, William, Shimon Mayak, and Haim Rabinowitch. Physiological and Molecular Characterization of the Response to Ethylene during Senescence of Carnation Genotypic Variants. United States Department of Agriculture, July 1995. http://dx.doi.org/10.32747/1995.7613011.bard.

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The senescence of carnation (Dianthus caryophyllus L.) flowers is associated with increased production of the phytohormone ethylene, which in turn serves to initiate and regulate the processes involved in programmed petal death. We investigated the regulation of ethylene production and petal senescence in carnation. Several carnation genotypes were identified that exhibited extended vase-life in comparison to flowers from typical commercial cultivars. The capacity of these genotypes to produce ethylene during postharvest vase-life and to respond to exogenous ethylene was investigated. Several genotypes, represented by 'Sandrosa' and 87-37G produced little ethylene durig their postharvest vase-life and as a result failed to exhibit the symptoms (in-rolling and wilting) typical of flowers producing elevated levels of ethylene. These genotypes were further separated by their capacity to respond to exogenous ethylene by both increased ethylene synthesis and premature petal senescence. In one case a genotype (799) was identified that was not capable of responding to exogenous ethylene by either increased ethylene production or premature petal senescence. The regulation of ethylene production during petal senescence was investigated both at the enzyme and gene levels. A full length cDNA was identified for the petal senescence-related ACC synthase gene. Utilizing this, and other ethylene biosynthetic pathway cDNA probes, an increase in both ACC synthase and ACC oxidase mRNAs were detected following ethylene treatment. An increase in ACC oxidase mRNA and enzyme activity was detected within 2-3 h following ethylene treatment, indicating the expression of this gene is an early response to ethylene. An investigation into the expression of novel proteins during petal senescence revealed a number of polypeptides increased in abundance and possibly play a role in the regulation or biochemical processes of senescence. One polypeptide of 70 kDa was identified as being encoded by the previously characterized gene SR12 and possibly represents a b-galactosidase involved in the remobilization of carbohydrates during senescence.
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Chamovitz, Daniel, and Albrecht Von Arnim. Translational regulation and light signal transduction in plants: the link between eIF3 and the COP9 signalosome. United States Department of Agriculture, November 2006. http://dx.doi.org/10.32747/2006.7696515.bard.

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The COP9 signalosome (CSN) is an eight-subunit protein complex that is highly conserved among eukaryotes. Genetic analysis of the signalosome in the plant model species Arabidopsis thaliana has shown that the signalosome is a repressor of light dependent seedling development as mutant Arabidopsis seedlings that lack this complex develop in complete darkness as if exposed to light. These mutant plants die following the seedling stage, even when exposed to light, indicating that the COP9 signalosome also has a central role in the regulation of normal photomorphogenic development. The biochemical mode of action of the signalosome and its position in eukaryotic cell signaling pathways is a matter of controversy and ongoing investigation, and recent results place the CSN at the juncture of kinase signaling pathways and ubiquitin-mediated protein degradation. We have shown that one of the many CSN functions may relate to the regulation of translation through the interaction of the CSN with its related complex, eukaryotic initiation factor (eIF3). While we have established a physical connection between eIF3 subunits and CSN subunits, the physiological and developmental significance of this interaction is still unknown. In an effort to understand the biochemical activity of the signalosome, and its role in regulating translation, we originally proposed to dissect the contribution of "h" subunit of eIF3 (eIF3h) along the following specific aims: (i) Isolation and phenotypic characterization of an Arabidopsis loss-of-function allele for eIF3h from insertional mutagenesis libraries; (ii) Creation of designed gain and loss of function alleles for eIF3h on the basis of its nucleocytoplasmic distribution and its yeast-two-hybrid interactions with other eIF3 and signalosome partner proteins; (iii) Determining the contribution of eIF3h and its interaction with the signalosome by expressing specific mutants of eIF3h in the eIF3h- loss-of function background. During the course of the research, these goals were modified to include examining the genetic interaction between csn and eif3h mutations. More importantly, we extended our effort toward the genetic analysis of mutations in the eIF3e subunit, which also interacts with the CSN. Through the course of this research program we have made several critical scientific discoveries, all concerned with the apparent diametrically opposed roles of eIF3h and eIF3e. We showed that: 1) While eIF3e is essential for growth and development, eIF3h is not essential for growth or basal translation; 2) While eIF3e has a negative role in translational regulation, eIF3h is positively required for efficient translation of transcripts with complex 5' UTR sequences; 3) Over-accumulation of eIF3e and loss-of-function of eIF3h both lead to cop phenotypes in dark-grown seedlings. These results were published in one publication (Kim et al., Plant Cell 2004) and in a second manuscript currently in revision for Embo J. Are results have led to a paradigm shift in translation research – eIF3 is now viewed in all systems as a dynamic entity that contains regulatory subuits that affect translational efficiency. In the long-term agronomic outlook, the proposed research has implications that may be far reaching. Many important plant processes, including developmental and physiological responses to light, abiotic stress, photosynthate, and hormones operate in part by modulating protein translation [23, 24, 40, 75]. Translational regulation is slowly coming of age as a mechanism for regulating foreign gene expression in plants, beginning with translational enhancers [84, 85] and more recently, coordinating the expression of multiple transgenes using internal ribosome entry sites. Our contribution to understanding the molecular mode of action of a protein complex as fundamental as eIF3 is likely to lead to advances that will be applicable in the foreseeable future.
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O'Neill, Sharman, Abraham Halevy, and Amihud Borochov. Molecular Genetic Analysis of Pollination-Induced Senescence in Phalaenopsis Orchids. United States Department of Agriculture, 1991. http://dx.doi.org/10.32747/1991.7612837.bard.

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The project investigated the molecular genetic and biochemical basis of pollination-induced senescence of Phalaenopsis flowers. This experimental system offered unique advantages in that senescence is strictly regulated by pollination, providing the basis to experimentally initiate and synchronize senescence in populations of flowers. The postpollination syndrome in the Phalaenopsis orchid system was dissected by investigating the temporal and spatial regulation of ACC synthase gene expression. In the stigma, pollen-borne auxin induces the expression of the auxin-regulated ACC synthase (PS-ACS2) gene, resulting in ACC synthesis within 1 h following pollination. Newly formed ACC is oxidized by basal constitutive ACC oxidase to ethylene, which then induces the expression of the ethylene-regulated ACC synthase(PS-ACS1) and oxidase (ACO1) genes for further autocatalytic production of ethylene. It is speculated that during the 6-h period following pollination, emasculation leads to the production or release of a sensitivity factor that sensitizes the cells of the stigma to ethylene. ACC and ethylene molecules are translocated from the stigma to the labellum and perianth where ethylene induces the expression of PS-ACS1 and ACO1 resulting in an increased production of ACC and ethylene. Organ-localized ethylene is responsible for inrolling and senescence of the labellum and perianth. The regulation of ethylene sensitivity and signal transduction events in pollinated flowers was also investigated. The increase in ethylene sensitivity appeared in both the flower column and the perianth, and was detected as early as 4 h after pollination. The increase in ethylene sensitivity following pollination was not dependent on endogenous ethylene production. Application of linoleic and linoleic acids to Phalaenopsis and Dendrobium flowers enhanced their senescence and promoted ethylene production. Several major lipoxygenase pathway products including JA-ME, traumatic acid, trans-2-hexenal and cis-3-hexenol, also enhanced flower senescence. However, lipoxygenase appears to not be directly involved in the endogenous regulation of pollination-induced Phalaenopsis and Dendrobium flower senescence. The data suggest that short-chain saturated fatty acids may be the ethylene "sensitivity factors" produced following pollination, and that their mode of action involves a decrease in the order of specific regions i the membrane lipid bilayer, consequently altering ethylene action. Examination of potential signal transduction intermediates indicate a direct involvement of GTP-binding proteins, calcium ions and protein phosphorylation in the cellular signal transduction response to ethylene following pollination. Modulations of cytosolic calcium levels allowed us to modify the flowers responsiveness to ethylene.
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Droby, Samir, Michael Wisniewski, Ron Porat, and Dumitru Macarisin. Role of Reactive Oxygen Species (ROS) in Tritrophic Interactions in Postharvest Biocontrol Systems. United States Department of Agriculture, December 2012. http://dx.doi.org/10.32747/2012.7594390.bard.

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To elucidate the role of ROS in the tri-trophic interactions in postharvest biocontrol systems a detailed molecular and biochemical investigation was undertaken. The application of the yeast biocontrol agent Metschnikowia fructicola, microarray analysis was performed on grapefruit surface wounds using an Affymetrix Citrus GeneChip. the data indicated that 1007 putative unigenes showed significant expression changes following wounding and yeast application relative to wounded controls. The expression of the genes encoding Respiratory burst oxidase (Rbo), mitogen-activated protein kinase (MAPK) and mitogen-activated protein kinase kinase (MAPKK), G-proteins, chitinase (CHI), phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS) and 4-coumarate-CoA ligase (4CL). In contrast, three genes, peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT), were down-regulated in grapefruit peel tissue treated with yeast cells. The yeast antagonists, Metschnikowia fructicola (strain 277) and Candida oleophila (strain 182) generate relatively high levels of super oxide anion (O2−) following its interaction with wounded fruit surface. Using laser scanning confocal microscopy we observed that the application of M. fructicola and C. oleophila into citrus and apple fruit wounds correlated with an increase in H2O2 accumulation in host tissue. The present data, together with our earlier discovery of the importance of H₂O₂ production in the defense response of citrus flavedo to postharvest pathogens, indicate that the yeast-induced oxidative response in fruit exocarp may be associated with the ability of specific yeast species to serve as biocontrol agents for the management of postharvest diseases. Effect of ROS on yeast cells was also studied. Pretreatment of the yeast, Candida oleophila, with 5 mM H₂O₂ for 30 min (sublethal) increased yeast tolerance to subsequent lethal levels of oxidative stress (50 mM H₂O₂), high temperature (40 °C), and low pH (pH 4). Suppression subtractive hybridization analysis was used to identify genes expressed in yeast in response to sublethal oxidative stress. Transcript levels were confirmed using semi quantitative reverse transcription-PCR. Seven antioxidant genes were up regulated. Pretreatment of the yeast antagonist Candida oleophila with glycine betaine (GB) increases oxidative stress tolerance in the microenvironment of apple wounds. ROS production is greater when yeast antagonists used as biocontrol agents are applied in the wounds. Compared to untreated control yeast cells, GB-treated cells recovered from the oxidative stress environment of apple wounds exhibited less accumulation of ROS and lower levels of oxidative damage to cellular proteins and lipids. Additionally, GB-treated yeast exhibited greater biocontrol activity against Penicillium expansum and Botrytis cinerea, and faster growth in wounds of apple fruits compared to untreated yeast. The expression of major antioxidant genes, including peroxisomal catalase, peroxiredoxin TSA1, and glutathione peroxidase was elevated in the yeast by GB treatment. A mild heat shock (HS) pretreatment (30 min at 40 1C) improved the tolerance of M. fructicola to subsequent high temperature (45 1C, 20–30 min) and oxidative stress (0.4 mol-¹) hydrogen peroxide, 20–60 min). HS-treated yeast cells showed less accumulation of reactive oxygen species (ROS) than non-treated cells in response to both stresses. Additionally, HS-treated yeast exhibited significantly greater (P≥0.0001) biocontrol activity against Penicillium expansum and a significantly faster (Po0.0001) growth rate in wounds of apple fruits stored at 25 1C compared with the performance of untreated yeast cells. Transcription of a trehalose-6-phosphate synthase gene (TPS1) was up regulated in response to HS and trehalose content also increased.
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Lers, Amnon, and Pamela J. Green. LX Senescence-Induced Ribonuclease in Tomato: Function and Regulation. United States Department of Agriculture, September 2003. http://dx.doi.org/10.32747/2003.7586455.bard.

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Natural leaf senescence, which occurs even when growth conditions are near optimal, has a negative influence on yield. Postharvest induced senescence contributes to the losses of quality in flowers, foliage, and vegetables. Strategies designed to control the senescence process in crop plants could therefore have great applied significance. However, the successful design of such strategies requires a better insight into the senescence machinery and control in higher plants. A main feature of senescence is the hydrolysis of macromolecules by hydrolases of various types such as ribonucleases (RNases) and proteases. Previously we had identified and characterized the tomato LX RNase gene demonstrating its transcript to be highly and specifically induced during senescence. This reported study was focused on LX but also had broadened our research to other senescence-associated nucleic acids degrading enzymes to learn about their function and the regulation of their encoding genes. Beside tomato we used parsley and Arabidopsis for the study of: the bi-functional nuclease which has a role in senescence. The study of different senescence- associated nucleases in few plant systems will allow a more general view on function and regulation of these enzymes in senescence. The specific original proposed objectives included: 1. Study the consequences of alterations in LX RNase level on tomato leaf senescence and general development; 2. Analyze stimuli which may participate in senescence-specific activation of the LX gene; 3. Clone the senescence-associated BFNI nuclease gene homologue from tomato. 4. Further characterize the sequences required for senescence-specific gene expression. Homozygous transgenic plants in which LX gene was either inhibited or over-expressed were generated. In both of these LX mutated plants no major phenotypic consequences were observed, which may suggests that LX is not essential for plant growth under optimal growth conditions. Lack of any abnormalities in the LX over-expressing lines suggests that special system exist to allow function of the RNase only when needed. Detailed analyses of growth under stress and consequences to RNA metabolism are underway. We have analyzed LX expression on the protein level demonstrating that it is involved also in petal senescing. Our results suggest that LX is responding to complex regulation involving developmental, organ dependent factors and responds differently to hormonal or environmental stimuli in the different plant organs. The cloned 1.4 kb promoter was cloned and its analysis revealed that probably not all required elements for senescence induction are included. Biochemical analysis of senescence-associated be-functional nucleases in the different plants, tomato, parsley and Arabidopsis, suggests they belong to a sub-class within the type I plant nucleases. The parsley PcNUC1/2 nuclease protein was purified from senescing leaves its and activity was studied in vitro revealing endo-, double strand, nucleolytic activity and exo-nucleolytic activity. Its encoding gene was cloned and found to be induced on the mRNA level. The promoter of the related Arabidopsis BFNI nuclease was shown in both tomato and Arabidopsis to be able and direct senescence-specific expression suggesting that, at least part, the gene is regulated on the transcriptional level and that the mechanism for this senescence-specific regulation is conserved between different plants. Few plants in which the BFNI gene is mutated were identified which are subjected now to detailed analysis. Our results suggest that the senescence-related nucleic acid degrading enzymes share similarities in both function and regulation between different plants and possibly have important functions in processes un-related to senescence. Still, the function of these enzymes, at least in some cases is not essential to plant development under optimal growth conditions. We are now at the stage which permits in depth investigation of the specific functions and mode of molecular regulation of senescence-associated nucleases with the aid of the research tools developed. The isolated senescence-specific promoter, shown to be active in heterologous plant system, could be utilized in agricultural-related biotechnological applications for retardation of senescence.
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Biogeochemical and biochemical pathway investigations of Cadmium in subarctic ecosystems using a Cadmium Accumulator Species (willow). US Geological Survey, 2010. http://dx.doi.org/10.3133/b21914.

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