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Letteratura scientifica selezionata sul tema "Calcium Metabolism"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 1 agosto 2024

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Articoli di riviste sul tema "Calcium Metabolism"

Pak, Charles Y. C. "Calcium Metabolism". Journal of the American College of Nutrition 8, sup1 (dicembre 1989): 46S—53S. http://dx.doi.org/10.1080/07315724.1989.10737969.

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Licata, Angelo A. "Calcium metabolism". Trends in Endocrinology & Metabolism 2, n. 6 (novembre 1991): 240. http://dx.doi.org/10.1016/1043-2760(91)90031-h.

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Stiffler, D. F. "Amphibian calcium metabolism". Journal of Experimental Biology 184, n. 1 (1 novembre 1993): 47–61. http://dx.doi.org/10.1242/jeb.184.1.47.

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Calcium is present in amphibian blood at a concentration similar to that in other vertebrates, about 1–2 mmol l-1. The fraction of free calcium in amphibians is lower than that in other tetrapod vertebrates because about 50% of the plasma Ca2+ is bound to plasma proteins and perhaps other molecules. Plasma [Ca2+] varies seasonally, increasing in spring and summer and decreasing in winter. Changes in plasma [Ca2+] also occur during larval development, as the concentration of this ion increases in larval forms as they approach metamorphosis. Calcium is exchanged at a variety of sites in animals. There is evidence for Ca2+ uptake across the skin and gills of larval anurans. It is also transported into the blood from the small intestine (especially the duodenum) and reabsorbed in renal tubules from the glomerular filtrate. The possibility of Ca2+ absorption from urine stored in the urinary bladder has not been confirmed, however. Calcium is stored in bone and in specialized endolymphatic sacs. This Ca2+ can be mobilized when the need arises. There are a number of endocrine and other humoral factors that appear to be involved in amphibian calcium metabolism. These include parathyroid hormone, calcitonin, vitamin D and prolactin.

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WALPERT, NAOMI. "CALCIUM METABOLISM DISORDERS". Nursing 20, n. 7 (luglio 1990): 60–64. http://dx.doi.org/10.1097/00152193-199007000-00022.

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Emkey, Ronald D., e Gregory R. Emkey. "Calcium Metabolism and Correcting Calcium Deficiencies". Endocrinology and Metabolism Clinics of North America 41, n. 3 (settembre 2012): 527–56. http://dx.doi.org/10.1016/j.ecl.2012.04.019.

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Walters, Barry NJ. "Calcium metabolism in pregnancy". Fetal and Maternal Medicine Review 1, n. 2 (luglio 1989): 213–22. http://dx.doi.org/10.1017/s0965539500000188.

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During pregnancy and lactation there are many changes in maternal calcium physiology which maintain homeostasis in the face of greatly altered calcium balance. In the course of fetal growth and development, 30g of calcium is incorporated into the fetus by term, an amount derived wholly from the maternal system. Most of this accumulates in the latter half of pregnancy, representing a net transfer of 200mg calcium/day (5mmoles). The fact that this is not achieved at the expense of the maternal skeleton is testimony to the conservative and protective adjustments that are seen in calcium metabolism in pregnancy. Furthermore, the changes must persist both in the puerperium and later when lactation presents a source of continuing maternal calcium loss to the suckling infant. The calcium content of human breast milk s i 6–9mmols calcium/l, two to three times the maternal serum level. In the course of one week a normal breast-fed at term infant takes two to three litres of milk, containing 10–30mmols of calcium. The maternal daily calcium intake recommended by the World Health Organization s i 1.25g (30mmol) of which only 25% is absorbed. Thus calcium loss from mother to baby is significant and may not be replaced by diet in many parts of the world.

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Massey, Linda K., e Susan J. Whiting. "Caffeine, Urinary Calcium, Calcium Metabolism and Bone". Journal of Nutrition 123, n. 9 (1 settembre 1993): 1611–14. http://dx.doi.org/10.1093/jn/123.9.1611.

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TERASHITA, Kenzo, Tetsuro NAKAMURA, Joji OSHIMA, Hajime ORIMO e Masayoshi YAMAGUCHI. "Calcium Metabolism and Arteriosclerosis". Journal of Japan Atherosclerosis Society 14, n. 4 (1986): 951–56. http://dx.doi.org/10.5551/jat1973.14.4_951.

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TERASHITA, Kenzo, Tetsuro NAKAMURA, Joji OOSHIMA, Hajime ORIMO e Masayoshi YAMAGUCHI. "Calcium Metabolism and Arteriosclerosis". Journal of Japan Atherosclerosis Society 15, n. 1 (1987): 315–18. http://dx.doi.org/10.5551/jat1973.15.1_315.

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TERASHITA, Kenzo, Tetsuro NAKAMURA, Joji OOSHIMA, Hajime ORIMO e Yoshiyuki SEYAMA. "Calcium Metabolism and Arteriosclerosis". Journal of Japan Atherosclerosis Society 16, n. 6 (1988): 895–901. http://dx.doi.org/10.5551/jat1973.16.6_895.

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Tesi sul tema "Calcium Metabolism"

Eraso, Pichot Abel. "Adaptive regulation of calcium excitability and energy metabolism by CREB-dependent transcription in astrocytes: study of the mechanisms governing astrocyte plasticity". Doctoral thesis, Universitat Autònoma de Barcelona, 2018. http://hdl.handle.net/10803/664170.

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Cada cop més evidencies suggereixen que els astròcits participen en les altes funcions cerebrals, controlant des de la transmissió sinàptica fins a les ones cerebrals globals i els processos d’aprenentatge i memòria. Diferents mecanismes han sigut proposats com a responsables d’aquests processos mediats per astròcits, entre ells, l’alliberació de gliotransmissors a partir de les senyals de calci així com la de lactat semblen els principals efectors. L’existència d’aquest control de les funcions cerebrals per part dels astròcits suggereix que aquestes cèl·lules poden regular les funcions cerebrals en resposta a experiència tan com les neurones, constituint el fenomen de plasticitat astrocitària. En neurones s’ha demostrat que el conegut factor de transcripció CREB, coordina les plasticitats sinàptica i intrínseca. El fet que, en astròcits, l’activació de CREB també està regulada per activitat cerebral, situa aquest factor de transcripció com a la diana ideal per promoure canvis dependents d’activitat en astròcits. En aquesta tesi hem analitzat l’efecte de l’activació de la transcripció depenent de CREB en astròcits, centrant-nos en l’excitabilitat del calci i en el metabolisme d’aquestes cèl·lules. Hem demostrat que l’activació de la transcripció depenent de CREB redueix les senyals citosòliques de calci a través del mitocondri a la vegada que augmenta l’alliberació de lactat, dos canvis que poden tenir impacte en la transmissió sinàptica. Una altra contribució important d’aquest estudi es l’anàlisi molecular dels mitocondris dels astròcits, que ha revelat que aquestes cèl·lules poden utilitzar metabòlits que no són glucosa, com ara àcids grassos, per respondre a les necessitats metabòliques energètiques. Els nostres resultats estableixen el CREB en astròcits con un eix de la plasticitat astrocitària i revelen la interacció entre la plasticitat i el metabolisme energètic en astròcits. Aquests descobriments constitueixen un avenç mecanístic i conceptual en el coneixement de la biologia dels astròcits i com aquestes cèl·lules poden controlar l’aprenentatge i la memòria.
An increasing body of evidence suggests that astrocytes participate in higher-brain functions, controlling from synaptic transmission to global brain waves and learning and memory processes. Different mechanisms have been proposed to mediate these astrocyte-dependent processes, astrocytic lactate release and calcium-dependent gliotransmission being the main known effectors. The existence of control of brain functions by astrocytes suggests that astrocytes may shape brain functions in response to experience as much as neurons, thus constituting the phenomenon of astrocyte plasticity. In neurons, the transcription factor CREB is the best known coordinator of synaptic and intrinsic plasticity. The fact that, in astrocytes, CREB activation is also activity-dependent, positions CREB as an ideal target to promote plasticity-related changes in astrocytes, too. In this thesis, we have analyzed the effect of the activation of CREB-dependent transcription in astrocytes, specifically regarding calcium signals and metabolism. We have demonstrated that activation of CREB-dependent transcription reduces cytosolic calcium events via mitochondria and increases in lactate release, which may have impact on synaptic transmission. An important contribution of the study is the molecular analysis of astrocytic mitochondria, which has revealed that astrocytes may use fuels other than glucose such as fatty acids to meet basic energy metabolic demands. Taken together, our results establish astrocytic CREB as a hub in astrocyte-plasticity and shed light on the interplay between plasticity and energy metabolism in astrocytes; these findings constitute a conceptual and mechanistic advance in the knowledge of astrocytic biology and how these cells may control learning and memory.

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Johnson, John Drysdale. "Stimulation of mitochondrial metabolism by calcium". Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315046.

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Redmond, Jean Patricia. "Ethnic differences in calcium, phosphate and bone metabolism". Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708405.

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O'Loughlin, Peter Damian. "Effects of growth and oophorectomy on calcium balance /". Title page, contents and abstract only, 1996. http://web4.library.adelaide.edu.au/theses/09PH/09pho516.pdf.

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Mody, Istvan. "Calcium regulation in long-term changes of neuronal excitability in the hippocampal formation". Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25929.

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The regulation of calcium (Ca²⁺) was examined during long-term changes of neuronal excitability in the mammalian CNS. The preparations under investigation included the kindling model of epilepsy, a genetic form of epilepsy and long-term potentiation (LTP) of neuronal activity. The study also includes a discussion of the possible roles of a neuron-specific calcium-binding protein (CaBP). The findings are summarized as follows: 1) The distribution of CaBP was determined in cortical areas of the rat using a specific radioimmunoassay. The protein was found to have an unequal distribution in various cortical areas with preponderence in ventral structures. 2) Extending previous studies on the role of CaBP in kindling-induced epilepsy, its decline was correlated to the number of evoked afterdischarges (AD's) during the process of kindling. 3) Marked changes in CaBP levels were also found in the brains of the epileptic strain of mice (El). The hippocampal formation and the dorsal occipital cortex contained significantly lower CaBP than the control (CF-1) strain. The induction of seizures further decreased the levels of CaBP in the El mice. These findings are indicative of a possible genetic impairment of neuronal Ca²⁺ homeostasis in the El strain. 4) The levels of total hippocampal Ca²⁺ and Zn²⁺ were measured by atomic absorption spectrophotometry in control and commissural-kindled animals. While no change was found in the total Ca²⁺ content of the region, hippocampal Zn²⁺ of kindled preparations was found to be significantly elevated. 5) To measure Ca²⁺ -homeostasis, the kinetic analysis of ⁴⁵Ca uptake curves was undertaken in the in vitro hippocampus. This technique was found to be a valid method for assessment of Ca²⁺-regulation in the CNS under both physiological and pathophysiological conditions. The effect of various extracellular Ca²⁺ concentrations, 2,3-dinitrophenol (DNP), calcitonin, nifedipine and 3-isobutyl-1-methylxanthine (IBMX) on ⁴⁵Ca uptake curves was examined in order to identify the two exchangeable Ca²⁺ pools derived through kinetic analysis. 6) The kinetic analysis of ⁴⁵Ca uptake curves revealed that Ca²⁺-regulation of the hippocampus is impaired following amygdala- and commissural kindling. The changes reflect an enhancement of a Ca²⁺ pool that includes free cytosolic Ca²⁺ and a concomitant decrease in the amount of buffered calcium probably as a result in the decrease of hippocampal CaBP levels. 7) A novel form of long-term potentiation (LTP) of neuronal activity in the CA1 region of the hippocampus is described. Perfusion of 100 uM of IBMX in the hippocampal slice preparation induced a long lasting increase in the amplitude of the stratum radiatum evoked population spike and EPSP responses with changes in synaptic efficacy as indicated by the altered input/output relationships. Intracellular correlates of IBMX-induced LTP included lowering of synaptic threshold and enhancement of the rate of rise of the EPSP with no alterations in the passive membrane characteristics of CA1 pyramidal neurons. The fact that IBMX was able to exert its effect even in the presence of the calcium-blocker cation Co²⁺, taken together with the drug's action on hippocampal exchangeable Ca²⁺, raises the possibility that the Ca²⁺ necessary for induction of LTP may be derived from an intraneuronal storage site. These studies indicate the significance of intracellular Ca²⁺ -regulatory mechanisms in long-term changes of neuronal excitability which occur in experimental models of epilepsy and long-term potentiation.
Medicine, Faculty of
Cellular and Physiological Sciences, Department of
Graduate

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Barbosa, Erika Grasiela Marques de Menezes [UNESP]. "Perfil metabólico de cálcio e ósseo de pacientes soropositivos para HIV em uso ou não da terapia antirretroviral". Universidade Estadual Paulista (UNESP), 2013. http://hdl.handle.net/11449/88689.

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Made available in DSpace on 2014-06-11T19:23:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-01-29Bitstream added on 2014-06-13T18:09:51Z : No. of bitstreams: 1 barbosa_egmm_me_arafcf.pdf: 437958 bytes, checksum: 3c5ca7946a683a97660f6cc74c0cab06 (MD5)
A potência e a eficácia das terapias antirretrovirais (TARV) aumentaram a expectativa de vida dos pacientes infectados pelo vírus da imunodeficiência humana. Entretanto, resultados de vários estudos sugerem que estas terapias também podem produzir modificações metabólicas, tais como as doenças ósseas. O objetivo do presente estudo foi avaliar a qualidade óssea e marcadores de formação e reabsorção óssea em pacientes infectados pelo HIV em uso ou não da TARV. Foi realizado um estudo transversal, com 50 homens adultos, em tratamento ou não com antirretrovirais. Foram aplicados métodos de avaliação do consumo alimentar, medidas antropométricas e avaliação da composição corporal e óssea utilizando a dual energy x-ray absorptiometry (DXA). Para a avaliação bioquímica foram utilizados os marcadores: hormônio do folículo estimulante (FSH), hormônio luteinizante (LH), paratormônio (PTH), testosterona, cálcio total, fósforo, magnésio, albumina, cálcio 24h, creatinina, uréia, fator 1 de crescimento semelhante a insulina (IGF-I), 25 hidroxivitamina D, osteocalcina e deoxipiridinolina urinária. Os resultados obtidos foram escritos na forma de artigo científico, sendo que o primeiro abordou a influência do tempo de uso da TARV na densidade mineral óssea e mostrou uma redução na massa óssea na maioria dos participantes avaliados e o consumo de cálcio foi adequado apenas no Grupo B1 em tratamento há mais de dois anos com antirretrovirais. O segundo artigo abordou o impacto da TARV nos marcadores do metabolismo ósseo e mineral e mostrou valor aumentado no marcador de reabsorção óssea em todos os grupos do estudo. Concluímos que a maioria dos participantes apresentou uma desmineralização óssea, principalmente com maior tempo de uso da TARV da classe de inibidores de transcriptase reversa...
The potency and efficacy of antiretroviral therapies (ART) have increased the life expectancy of HIV-infected patients. However, the results of various studies suggest that these therapies may also produce metabolic modifications such as bone diseases. The objective of the present study was to evaluate the bone quality and the markers of bone formation and reabsorption in HIV-seropositive patients using or not ART. A cross-sectional study was conducted on 50 adult men treated or not with ART. Methods for the evaluation of food consumption were applied, as well as anthropometric measurements and the evaluation of body and bone composition using dual energy x-ray absorptiometry (DXA). The following markers were used for biochemical evaluation: follicle stimulating hormone (FSH), luteinizing hormone (LH), parathormone (PTH), testosterone, total calcium, phosphorus, magnesium, albumin, 24h calcium, creatinine, urea, insulin-like growth factor 1 (IGF-I), 25 hydroxyvitamin D, osteocalcin, and urinary deoxypyridinoline. The results obtained were presented in the form of scientific articles. The first concerned the influence of the time of ART use on bone mineral density and showed a reduction of bone mass in most of the participants evaluated, with calcium consumption being adequate only in Group B1 under treatment with ARVs for more than two years. The second concerned the impact of ART on the markers of bone and mineral metabolism and showed an increase in the bone resorption marker in all study groups. We conclude that most of the volunteers presented bone demineralization, especially after a longer time of use of ART of the nucleoside reverse transcriptase inhibitor class. The increased bone remodeling indicates a greater... (Complete abstract click electronic access below)

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Pasanisi, F. "Clinical pharmacology of calcium antagonists". Thesis, University of Glasgow, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381477.

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Lirvall, Margareta. "Dynamics and gene expression of growth factor receptors in human cultured skin cells : effects of UV radiation and calcium on EGF- and PDGF-receptors /". Linköping : Univ, 2001. http://www.bibl.liu.se/liupubl/disp/disp2001/med674s.pdf.

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Efanov, Alexander. "Stimulation of insulin secretion independently from changes in cytosolic free Ca²⁺-concentration : studies with imidazolines and inositol polyphosphates /". Stockholm, 1999. http://diss.kib.ki.se/1999/91-628-3876-8/.

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Tsai, Jon A. "Parathyroid hormone-related protein (PTHrP), calcium and human osteoblast-like cells /". Stockholm, 2000. http://diss.kib.ki.se/2000/91-628-4174-2.

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Libri sul tema "Calcium Metabolism"

Fiskum, Gary, a cura di. Cell Calcium Metabolism. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4684-5598-4.

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Sotelo, J. R., e J. C. Benech, a cura di. Calcium and Cellular Metabolism. Boston, MA: Springer US, 1997. http://dx.doi.org/10.1007/978-1-4757-9555-4.

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J, Danks, American Society for Bone and Mineral Research., International Bone and Mineral Society. e Joint Meeting of the American Society for Bone and Mineral Research and the International Bone and Mineral Scoiety (2nd : 1998 : San Francisco, Calif.), a cura di. Calcium metabolism: Comparative endocrinology. Bristol [England]: Bioscientifica, 1999.

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John, Martin T., e Raisz Lawrence G. 1925-, a cura di. Clinical endocrinology of calcium metabolism. New York: Dekker, 1987.

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Felix, Bronner, a cura di. Intracellular calcium regulation. New York: Wiley-Liss, 1990.

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1927-, Bader Hermann, a cura di. Intracellular calcium regulation: Proceedings of the International Symposium "Intracellular Calcium Regulation", Ulm/Neu-Ulm (West Germany), August 6-8, 1984. Manchester, UK: Manchester University Press, 1986.

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1927-, Bader Hermann, a cura di. Intracellular calcium regulation. Manchester: Manchester University Press, 1986.

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J, Vogel Hans, a cura di. Calcium-binding protein protocols. Totowa, NJ: Humana Press, 2002.

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Anderson, Shawna. Calcium metabolism in pseudomonas fluorescens ATCC 13525. Sudbury, Ont: Laurentian University, 1991.

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C, Tsang Reginald, a cura di. Calcium and magnesium metabolism in early life. Boca Raton: CRC Press, 1995.

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Capitoli di libri sul tema "Calcium Metabolism"

Lind, L., e S. Ljunghall. "Calcium Metabolism". In Frontiers of Hormone Research, 67–86. Basel: KARGER, 1999. http://dx.doi.org/10.1159/000061009.

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Tiosano, D., Z. Hochberg e A. D. Rogol. "Calcium metabolism". In Practical Algorithms in Pediatric Endocrinology, 68–75. Basel: KARGER, 2007. http://dx.doi.org/10.1159/000105110.

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Lotersztajn, Sophie, Catherine Pavoine, Ariane Mallat, Dominique Stengel, Paul Insel e Françoise Pecker. "Hormonal Inhibition of the Liver Plasma Membrane (Ca2+ —Mg2+ ) ATPase is Mediated by a Gs-like Protein". In Cell Calcium Metabolism, 3–11. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4684-5598-4_1.

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Dean, William L., e Samuel Evans Adunyah. "Effects of cAMP-Dependent, Calmodulin-Dependent, and C-Type Protein Kinases on Platelet Calcium Transport". In Cell Calcium Metabolism, 83–91. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4684-5598-4_10.

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Tada, Michihiko, Masaaki Kadoma e Junichi Fujii. "Molecular Structure of Canine Cardiac Phospholamban, the Regulatory Protein of Ca Pump ATPase of Sarcoplasmic Reticulum". In Cell Calcium Metabolism, 93–101. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4684-5598-4_11.

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Vercesi, Anibal E., Lucia Pereira-Da-Silva, Ione S. Martins, Eva G. S. Carnieri, Celene F. Bernardes e Marcia M. Fagian. "Ca2+ Transport by Liver and Plant Mitochondria". In Cell Calcium Metabolism, 103–11. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4684-5598-4_12.

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Berridge, Michael John. "Inositol Lipids and Intracellular Communication". In Cell Calcium Metabolism, 115–24. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4684-5598-4_13.

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Williamson, John R., Roy A. Johanson, Carl A. Hansen e Jonathan R. Monck. "Receptor-Mediated Ca2+ Signaling". In Cell Calcium Metabolism, 125–41. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4684-5598-4_14.

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Kirk, C. J., J. B. Parry, R. F. Irvine, R. H. Michell e S. B. Shears. "Metabolism of Ins(1,3,4)P3 by Rat Liver Homogenates". In Cell Calcium Metabolism, 143–48. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4684-5598-4_15.

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Renard, D., e J. Poggioli. "Evidence for the Existence of the Inositol Tris/Tetrakisphosphate Pathway in Rat Heart". In Cell Calcium Metabolism, 149–56. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4684-5598-4_16.

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Atti di convegni sul tema "Calcium Metabolism"

Pascual-González, Yuliana, Ester Cuevas, Patricio Luburich e Vanesa Vicens-Zygmunt. "Pulmonary alveolar microlithiasis: genetic disorder and concomitant altered calcium metabolism". In ERS International Congress 2020 abstracts. European Respiratory Society, 2020. http://dx.doi.org/10.1183/13993003.congress-2020.3490.

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Lefaix, Laura, Marc Navarro, Carme Nogués, Andreu Blanquer e Gonzalo Murillo. "Modulation of Calcium Metabolism on Osteosarcoma Cells Using Ultrasound-Actuated Piezoelectric Nanogenerators". In 2024 IEEE 37th International Conference on Micro Electro Mechanical Systems (MEMS). IEEE, 2024. http://dx.doi.org/10.1109/mems58180.2024.10439536.

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Cameli, Paolo, Carla Caffarelli, Miriana D'Alessandro, Laura Bergantini, Martina Armati, Maria Dea Tomai Pitinca, Piersante Sestini, Stefano Gonnelli e Elena Bargagli. "The role of calcium metabolism assessment in the clinical setting of interstitial lung diseases". In ERS International Congress 2021 abstracts. European Respiratory Society, 2021. http://dx.doi.org/10.1183/13993003.congress-2021.pa706.

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Del Maschio, A., M. Albors, F. Bucchi, M. Tomasiak, V. Bertele, C. Cerletti e G. de Gaetano. "HUMAN POLYMORPHONUCLEAR LEUKOCYTE ACTIVATION INDUCED BY PLATELET ACTIVATING FACTOR (PAF)." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643482.

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Human polymorphonuclear leukocytes (PMNs) loaded with the photoprotein Aequorin, were exposed to PAF in the presence of extracellular Ca2+ (1 mM). PMNs aggregation measured In the “Platelet Ionized Calcium Aggregometer” (P.I.C.A.) was dependent on the concentration of the stimulus. Ca2+ cytoplasmatic increase was monitored in parallel at concentrations of PAF which did not modify cellular integrity (10-7-10-5M). The intracellular Ca2+ flux (up to 19±3 µM) triggered by PAF was also concentration-dependent. In order to establish the role played by this intracellular messenger, we studied some cellular responses possibly related to Ca2+ mobilization: enzymatic release, oxygen radicals production, and arachidonic acid metabolism. PAF induced release of both lysozyme , and β-glucuronldase (15% to 20% of the total enzyme content at the maximal concentration). However PAF (10-712-10“Vl) stimulated the production of only small amounts of oxygen radicals as compared to Phorbol Myristate Acetate (PMA). Leukotriene B4 (LTB4), the main arachidonic acid metabolite in PMNs and the products of its catabolism (20-OH and 20-C00H LTBO were assayed by two different technics (HPLC and RIA) in the same cellular suspensions. PAF (10-4 M)-stimulated PMNs (0.5-2xl07 cells/ml) did not produce any detectable amount of these arachidonic acid metabolites. In contrast, calcium ionophore A 23187 (2 μM)-stimulated PMNs (in the same range of cellular concentration) produce up to 170 ng/ml of LTB4. In conclusion, cytoplasmatic Ca2+ increase in PAF-stimulated PMNs was not accompanied either by oxygen radicals production or by activation of arachidonic acid metabolism catalyzed by 5-1 ipoxygenase.

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Shrestha, Rajiv P., Yossi Chait, Christopher V. Hollot, Stuart Chipkin e Claus P. Schmitt. "A Mathematical Model of Parathyroid Hormone Response to Acute Changes in Plasma Ionized Calcium Concentration in Humans". In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-67551.

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A complex bio-mechanism, referred to as calcium homeostasis, regulates plasma ionized calcium (Ca++) concentration in the human body to within a narrow physiologic range which is crucial for maintaining normal physiology and metabolism. In this paper we present a qualitative model of the calcium homeostatic system and then focus on a particular sub-system, termed Ca-PTH axis. We consider the dynamics of the axis involving the response of the parathyroid glands to acute changes in plasma Ca++ concentration. We use a two-pool, linear time-varying model to describe the Ca-PTH axis. We show that this model, parameterized using a guided iterative parametrization scheme and induced hypocalcemic clamp test data, successfully predicts dynamics observed in clinical tests of induced hypercalcemia in normal humans.

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Galvão, Adriele, Karina Fernandes, Larissa de Conto e Paula Karina. "Hypothyroidism and hyperthyroidism The prevalence of hypothyroidism and hyperthyroidism and its impact on the lives of patients with the disease". In II INTERNATIONAL SEVEN MULTIDISCIPLINARY CONGRESS. Seven Congress, 2023. http://dx.doi.org/10.56238/homeinternationalanais-059.

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Abstract The thyroid gland performs functions of paramount importance for the functioning of the human body, being responsible for the production of three (3) hormones, thyroxine (T4) and tri-iodothyronine (T3), which regulate metabolism, and calcitonin, which is linked to the regulation of calcium concentration in the body. It is positioned inferiorly to the larynx and extends under the lateral and anterior regions of the trachea. Among the thyroid disorders are hypothyroidism and hyperthyroidism, which impact the metabolism. Both diseases affect a large percentage of the population, where the prevalence varies from region to region, however they have different symptoms.

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Mointire, V. L., A. J. Frangos, G. B. Rhee, G. S. Eskin e R. E. Hall. "RHEOLOGY AND CELL ACTIVATION". In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643988.

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The subject of this work is to examine the hypothesis that some sublytic levels of mechanical perturbation of cells can stimulate cell metabolism. As a marker metabolite, we have chosen arachidonic acid. Principal metabolites for platelets include the cyclooxygenase product thromboxane A2(TXA2) and the lipoxygenase product 12-hydroperoxy-eicosatetraenoic acid (12-HPETE). Polymorphonuclear leukocytes (PMNLs) initally produce principally 5-HPETE, somtimes leading to the formation leukotrienes, though many other metabolites of arachidonic acid have been isolated from activated neutrophils. Human umbilical vein endothelial cells utilize arachidonic acid to produce mainly prostaglandin I2(PGI2). All of these metabolites are biologically active and modulate cell function - sometimes in quite contrasting ways. We will show that levels of sublytic mechanical stress exposure can stimulate arachidonic acid metabolism in all three of the cell types mentioned above. The biological implications of this stress/metabolism coupling may be quite far reaching.Human platelets, leukocytes and endothelial cells all appear to be sensitive to mechanical stress induced activation of arachidonic acid metabolism. Sheared PRP exhibited greatly increased synthesis of 12-HETE and surprisingly little thromboxane B2 production. This indicates that shear stress stimulation of platelets may produce quite different arachidonic acid metabolism than that seen with many direct chemical stimuli, such as thrombin or collagen.Our data demonstrate that a substance derived from shear induced platelet activation may activate the C-5 lipoxygenase of human PMNL under stress, leading to the production of LTB4. We hypothesize that this substance maybe 12-HPETE. LTB4 is known to be a very potent chemotactic factor and to induce PMNL aggregation and degranulation. Our studies provide further evidence that lipoxygenase products of one cell type can modulate production of lipoxygenase products in a second cell type, and that shear stress can initiate cell activation. This kind of coupling could have far reaching implications in terms of our understanding of cell/cell interaction in flowing systems, such as acute inflammation, artificial organ implantation and tumor metastasis.The data on PGI2 production by endothelial cells demonstrate that physiological levels of shear stress can dramatically increase arachidonic acid metabolism. Step increases in shear stress lead to a burst in production of PGI2 which decayed to a steady state value in several minutes. This longer term stimulation of prostacyclin production rate increased linearly with shear stress over the range of 0-24 dynes/cm2. In addition, pulsatile flow of physiological frequency and amplitude caused approximately 2.4 times the PGI2 production rate as steady flow with the same mean stress. Although only PGI2 was measured, it is likely that other arachidonic acid metabolites of endothelial cells are also affected by shear stress.The ability of cells to respond to external stimuli involves the transduction of a signal across the plasma membrane. One such external stimulus appears to be fluid shear stress. Steady shear flow induces cell rotation in suspended cells, leading to a periodic membrane loading, with the peak stress proportional to the bulk shear stress. On anchorage-dependent cells, such as endothelial cells, steady shear stress may act by amplifying the natural thermal or Brownian fluttering or rippling of the membrane. There are several possible mechanisms by which shear stress induced membrane perturbation could mimic a hormone/receptor interaction, leading to increased intracellular metabolism. Shear stress may induce increased phospholipase C activity, caused by translocation of the enzyme, increased substrate (arachidonic acid) pool availability to phospholipase C (particularly from that stored in phosphoinositols) due to shear-induced membrane movements or changes in membrane fluidity, direct activation of calcium - activated phospholipase A2 by increased membrane calcium ion permeability, or most probably by a combination of these mechanisms.

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Yelamarty, Rao V., Joseph Y. Cheung e Francis T. S. Yu. "Measurement of calcium in a single cell with a digitizing imaging fluorescence microscope". In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1988. http://dx.doi.org/10.1364/oam.1988.thff2.

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Optical section microscopy furnishes advantages over physical sectioning in visualizing the 3-D structure within a living cell. A hybrid digital-coupled fluorescence microscope for optical sectioning the specimen has been developed to measure the 3-D distribution of calcium in a single cardiac cell. The cell is initially loaded with fura-2, a fluorescent calcium-sensitive Indicator, and a stack of sectional fluorescent emission Images corresponding to different focal settings along the microscope’s axis of the specimen are obtained and then digitized for postprocessing. The experimental defocused point spread and contrast transfer functions of the overall system have been measured using the Ealing resolution target. Each sectional image of the stack is then processed digitally, using spread functions, by a VAX 11/780 to eliminate the defocused light contribution using the method described by Agard.1 The stack of 2-D processed images is then displayed on a multiple pixel system to observe the 3-D distribution. We show results of 3-D calcium distribution in a cardiac muscle cell and its dynamic variation during metabolism achieved by our system.

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Okuma, M., K. Kanaji, S. Sensaki e H. Uchino. "EFFECTS OF DILAZEP ON CYTOPLASMIC CALCIUM ION CONCENTRATION AND ARACHIDONIC ACID METABOLISM IN HUMAN PLATELETS AND NEUTROPHILS." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643438.

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We studied effects of dilazep(DZ), an antiplatelet drug, on the cytoplasmic Ca2+ concentration ([Ca2+]-i) and arachidonic acid (AA) metabolism in human platelets and neutrophils. [Ca2+]i of aequor-in-loaded platelets was estimated by using the platelet ionized calcium aggregometer. AA metabolism was studied by the determination of AA metabolites including hydroxyheptadecatrienoic acid (HHT), hydroxyeicosatetraenoic acid (HETE) and leukotriene B4 (LTB4) by reversed-phase high-performance liquid chromatography. When aequorin-loaded platelets were preincubated with DZ (0−0.5 mM) for 1 min at 37°C, both platelet aggregation and [Ca2+]i elevation induced by thrombin, AA and collagen were inhibited by DZ in a concentration dependent manner, while only aggregation was inhibited after stimulation by the calcium ionophore A23187 (1 yM). Both influx and release of Ca2+ into platelet cytoplasm induced by thrombin or AA were inhibited by DZ, while neither of them was affected when induced by A23187. The production of HHT and 12-HETE by the reaction of 100 yM AA with platelets preincubated with DZ (0−1 mM) was not inhibited, whereas their production by throirfbin (10 u/ml) was remarkably inhibited by DZ in a concentration dependent manner. When DZ (0−0.3 mM)-treated neutrophils were incubated with 5 μM A23187 in the presence or absence of 20 μM AA, the production of LTB4 and 5-HETE was increased by DZ in the presence of AA, whereas their production was inhibited by DZ in its absence. When platelet/neutrophil mixtures preincubated with DZ (0−0.3 mM) and cytochalasin B were stimulated by thrombin (5 u/ml) in the presence of FMLP, DZ inhibited LTB4 production in a concentration dependent manner, while 5S,12S-diHETE synthesis was enhanced by lower concentrations of DZ and inhibited by its higher concentrations (> 0.1 mM).Thus, DZ inhibits platelet aggregation induced by any agonist including A23183, while [Ca2+]i elevation is inhibited by the drug only when it is induced by the receptor-mediated agonist. Furthermore, it was suggested that AA liberation from phospholipids in platelets and neutrophils was inhibited by DZ, leading to reduced production of all endogenous AA metabolites by these cells after appropriate stimulation, although lipoxygenase metabolites of liberated or exogenous AA could be increased.

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Fuzimoto, T., K. Fuzimura e A. Kuramoto. "MEASUREMENT OF PLATELET IONIZED CALCIUM IN PATIENTS WITH MYELOPROLIFERATIVE DISORDERS BY AEQUORIN METHOD". In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644573.

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In myeloproliferative disorders(MPD), bleeding tendency and thrombosis are encountered occasionally in the presence of high platelet counts. It has been reported that there are some abnormalities of membrane glycoprotein or arachidonate metabolism in platelets of MPD. We measured the intracellular change of calcium levels[Cai2+] after stimulation in platelets of the patients with MPD by Aequorin method. Eleven cases of chronic myelogenous leukemia(CML), 7 cases of polycythemia vera(PV), 4 cases of essential thrombocythemiaCET^ and 12 normal adults were studied, and as stimulators 0.5 U/ml thrombin and 2.5 μg/ml collagen were used. In the patients with CML, PV and ET, maximum intracellular calcium level was significantly lower and the reaction period reaching to the peak calcium level(the arrival time) was significantly prolonged than the normals after thrombin stimulation. On collagen stimulation, maximum[Cai2+] level in patient with CML and PV was significantly lower and the arrival time in patient with CML and ET was significantly prolonged than the normals. No correlation was found between maximum [Cai2+] level and maximum aggregation rate or platelet counts in those patients. The increasing rate of intracellular calcium levels after stimulation with A23187 in the presence of various concentration of extracellular calcium was proved lower in CML than in the normal. [45Ca2+] uptake rate into the CML platelets after thrombin stimulation showed lower rate compaired with normals. These results suggest that platelets in patients with MPD have some abnormalities of calcium influx mechanism. We already reported that platelet membrane glycoprotein (GP)IIIa was increased significantly in MPD platelets. The study is going to examine the relationship between this membrane abnormality and impaired calcium influx in MPD.

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Rapporti di organizzazioni sul tema "Calcium Metabolism"

Fromm, Hillel, Paul Michael Hasegawa e Aaron Fait. Calcium-regulated Transcription Factors Mediating Carbon Metabolism in Response to Drought. United States Department of Agriculture, giugno 2013. http://dx.doi.org/10.32747/2013.7699847.bard.

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Original objectives: The long-term goal of the proposed research is to elucidate the transcription factors, genes and metabolic networks involved in carbon metabolism and partitioning in response to water deficit. The proposed research focuses on the GTLcalcium/calmodulinbindingTFs and the gene and metabolic networks modulated by these TFs in Arabidopsis thaliana. The specific objectives are as follows. Objective-1 (USA): Physiological analyses of GTL1 loss- and gain-of-function plants under water sufficient and drought stress conditions Objective 2 (USA / Israel-TAU): Characterizion of GTL target genes and bioinformatic analysis of data to eulcidate gene-network topology. Objective-3 (Israel-TAU): Regulation of GTLmediated transcription by Ca²⁺/calmodulin: mechanism and biological significance. Objective-4 (Israel-BGU): Metabolic networks and carbon partitioning in response to drought. Additional direction: In the course of the project we added another direction, which was reported in the 2nd annual report, to elucidate genes controlling drought avoidance. The TAU team has isolated a few unhydrotropic (hyd) mutants and are in the process of mapping these mutations (of hyd13 and hyd15; see last year's report for a description of these mutants under salt stress) in the Arabidopsis genome by map-based cloning and deep sequencing. For this purpose, each hyd mutant was crossed with a wild type plant of the Landsberg ecotype, and at the F2 stage, 500-700 seedlings showing the unhydrotropic phenotype were collected separately and pooled DNA samples were subkected to the Illumina deep sequencing technology. Bioinformatics were used to identify the exact genomic positions of the mutations (based on a comparison of the genomic sequences of the two Arabidopsis thaliana ecotypes (Columbia and Landsberg). Background: To feed the 9 billion people or more, expected to live on Earth by the mid 21st century, the production of high-quality food must increase substantially. Based on a 2009 Declaration of the World Summit on Food Security, a target of 70% more global food production by the year 2050 was marked, an unprecedented food-production growth rate. Importantly, due to the larger areas of low-yielding land globally, low-yielding environments offer the greatest opportunity for substantial increases in global food production. Nowadays, 70% of the global available water is used by agriculture, and 40% of the world food is produced from irrigated soils. Therefore, much needs to be done towards improving the efficiency of water use by plants, accompanied by increased crop yield production under water-limiting conditions. Major conclusions, solutions and achievements: We established that AtGTL1 (Arabidopsis thaliana GT-2 LIKE1) is a focal determinant in water deficit (drought) signaling and tolerance, and water use efficiency (WUE). The GTL1 transcription factor is an upstream regulator of stomatal development as a transrepressor of AtSDD1, which encodes a subtilisin protease that activates a MAP kinase pathway that negatively regulates stomatal lineage and density. GTL1 binds to the core GT3 cis-element in the SDD1 promoter and transrepresses its expression under water-sufficient conditions. GTL1 loss-of-function mutants have reduced stomatal number and transpiration, and enhanced drought tolerance and WUE. In this case, higher WUE under water sufficient conditions occurs without reduction in absolute biomass accumulation or carbon assimilation, indicating that gtl1-mediated effects on stomatal conductance and transpiration do not substantially affect CO₂ uptake. These results are proof-of-concept that fine-tuned regulation of stomatal density can result in drought tolerance and higher WUE with maintenance of yield stability. Implications: Accomplishments during the IS-4243-09R project provide unique tools for continued discovery research to enhance plant drought tolerance and WUE.

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Kohrt, Wendy M. Disruption of Calcium Homeostasis during Exercise as a Mediator of Bone Metabolism. Fort Belvoir, VA: Defense Technical Information Center, ottobre 2013. http://dx.doi.org/10.21236/ada593122.

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Kohrt, Wendy M. Disruption of Calcium Homeostasis during Exercise as a Mediator of Bone Metabolism. Fort Belvoir, VA: Defense Technical Information Center, ottobre 2014. http://dx.doi.org/10.21236/ada615544.

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Chalutz, Edo, Michael Wisniewski, Samir Droby, Yael Eilam e Ilan Chet. Mode of Action of Yeast Biocontrol Agents of Postharvest Diseases of Fruits. United States Department of Agriculture, giugno 1996. http://dx.doi.org/10.32747/1996.7613025.bard.

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In a previous BARD-supported study, three of the investigators of this research were involved in a study on biological control of postharvest diseases of citrus and deciduous fruits. Several naturally occurring, non-antibiotic producing yeast antagonists were identified. Application of some of these antagonists resulted in very high levels of biocontrol under laboratory conditions but lower efficacy in semi-commercial tests. It was felt that the lack of knowledge on the mode of action of the biocontrol agents was limiting their efficient use. The current study was aimed at narrowing this gap in our knowledge. Two specific objectives were outlined: to study the mechanism by which calcium salts enhance biocontrol activity and to determine the role, if any, of the yeast extracellular materials and/or enzymes which degrade fungal cell walls during the interaction between the antagonists, the pathogen and the host. CaCl2 but not MgCl2, inhibited spore germination, and germ-tube elongation of Botrytis cinerea, Penicillium expansum and P. digitatum in culture. It also inhibited the pectinolytic activity of the pathogens. Biocontrol of apple decay by isolate 182 of Candida oleophila, an effective biocontrol agent, was enhanced by the addition of CaCl2 whereas there was no effect on the biocontrol activity of isolate 247 of this yeast. Similarly, CaCl2 enhanced efficacy of the US-7 isolate of Pichia guilliermondii in reducing infection of P. digitatum in citrus fruit. CaCl2 by itself also reduced the infection of peel wounds and stimulated ethylene production by grapefruit peel. This antagonist exhibited a very high ability to maintain cytosolic Ca2+ homeostasis when exposed to high CaCl2 concentrations. It is postulated, therefore, that enhanced biocontrol activity by calcium is the result of direct inhibition of the pathogen by calcium ions on spore germination and metabolism and indirectly due to the ability of the biocontrol agent to maintain normal metabolism in the presence of high levels of calcium. The extracellular materials produced by P. guilliermondii in culture and on the fruit inhibited, at low concentrations, the pathogen in culture and reduced percent infection of the fruit. The direct inhibition of the pathogen by these materials may thus be involved in the mode of action of the antagonist. This study contributed to our knowledge on the action of calcium salts and the yeast antagonist extracellular materials on biocontrol activity and will contribute to a more efficient use of this technology in the control of postharvest diseases of fruits.

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Fromm, Hillel, e Joe Poovaiah. Calcium- and Calmodulin-Mediated Regulation of Plant Responses to Stress. United States Department of Agriculture, settembre 1993. http://dx.doi.org/10.32747/1993.7568096.bard.

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We have taken a molecular approach to clone cellular targets of calcium/calmodulin (Ca2+/CaM). A 35S-labeled recombinant CaM was used as a probe to screen various cDNA expression libraries. One of the isolated clones from petunia codes for the enzyme glutamate decarboxylase (GAD) which catalyzes the conversion of glutamate to g-aminobutyric acid (GABA). The activity of plant GAD has been shown to be dramatically enhanced in response to cold and heat shock, anoxia, drought, mechanical manipulations and by exogenous application of the stress phytohormone ABA in wheat roots. We have purified the recombinant GAD by CaM-affinity chromatography and studied its regulation by Ca2+/CaM. At a physiological pH range (7.0-7.5), the purified enzyme was inactive in the absence of Ca2+ and CaM but could be stimulated to high levels of activity by the addition of exogenous CaM (K0.5 = 15 nM) in the presence of Ca2+ (K 0.5 = 0.8 mM). Neither Ca2+ nor CaM alone had any effect on GAD activity. Transgenic tobacco plants expressing a mutant petunia GAD lacking the CaM-binding domain, or transgenic plants expressing the intact GAD were prepared and studied in detail. We have shown that the CaM-binding domain is necessary for the regulation of glutamate and GABA metabolism and for normal plant development. Moreover, we found that CaM is tightly associated with a 500 kDa GAD complex. The tight association of CaM with its target may be important for the rapid modulation of GAD activity by Ca2+ signaling in response to stresses.

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Or, Etti, David Galbraith e Anne Fennell. Exploring mechanisms involved in grape bud dormancy: Large-scale analysis of expression reprogramming following controlled dormancy induction and dormancy release. United States Department of Agriculture, dicembre 2002. http://dx.doi.org/10.32747/2002.7587232.bard.

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The timing of dormancy induction and release is very important to the economic production of table grape. Advances in manipulation of dormancy induction and dormancy release are dependent on the establishment of a comprehensive understanding of biological mechanisms involved in bud dormancy. To gain insight into these mechanisms we initiated the research that had two main objectives: A. Analyzing the expression profiles of large subsets of genes, following controlled dormancy induction and dormancy release, and assessing the role of known metabolic pathways, known regulatory genes and novel sequences involved in these processes B. Comparing expression profiles following the perception of various artificial as well as natural signals known to induce dormancy release, and searching for gene showing similar expression patterns, as candidates for further study of pathways having potential to play a central role in dormancy release. We first created targeted EST collections from V. vinifera and V. riparia mature buds. Clones were randomly selected from cDNA libraries prepared following controlled dormancy release and controlled dormancy induction and from respective controls. The entire collection (7920 vinifera and 1194 riparia clones) was sequenced and subjected to bioinformatics analysis, including clustering, annotations and GO classifications. PCR products from the entire collection were used for printing of cDNA microarrays. Bud tissue in general, and the dormant bud in particular, are under-represented within the grape EST database. Accordingly, 59% of the our vinifera EST collection, composed of 5516 unigenes, are not included within the current Vitis TIGR collection and about 22% of these transcripts bear no resemblance to any known plant transcript, corroborating the current need for our targeted EST collection and the bud specific cDNA array. Analysis of the V. riparia sequences yielded 814 unigenes, of which 140 are unique (keilin et al., manuscript, Appendix B). Results from computational expression profiling of the vinifera collection suggest that oxidative stress, calcium signaling, intracellular vesicle trafficking and anaerobic mode of carbohydrate metabolism play a role in the regulation and execution of grape-bud dormancy release. A comprehensive analysis confirmed the induction of transcription from several calcium–signaling related genes following HC treatment, and detected an inhibiting effect of calcium channel blocker and calcium chelator on HC-induced and chilling-induced bud break. It also detected the existence of HC-induced and calcium dependent protein phosphorylation activity. These data suggest, for the first time, that calcium signaling is involved in the mechanism of dormancy release (Pang et al., in preparation). We compared the effects of heat shock (HS) to those detected in buds following HC application and found that HS lead to earlier and higher bud break. We also demonstrated similar temporary reduction in catalase expression and temporary induction of ascorbate peroxidase, glutathione reductase, thioredoxin and glutathione S transferase expression following both treatments. These findings further support the assumption that temporary oxidative stress is part of the mechanism leading to bud break. The temporary induction of sucrose syntase, pyruvate decarboxylase and alcohol dehydrogenase indicate that temporary respiratory stress is developed and suggest that mitochondrial function may be of central importance for that mechanism. These finding, suggesting triggering of identical mechanisms by HS and HC, justified the comparison of expression profiles of HC and HS treated buds, as a tool for the identification of pathways with a central role in dormancy release (Halaly et al., in preparation). RNA samples from buds treated with HS, HC and water were hybridized with the cDNA arrays in an interconnected loop design. Differentially expressed genes from the were selected using R-language package from Bioconductor project called LIMMA and clones showing a significant change following both HS and HC treatments, compared to control, were selected for further analysis. A total of 1541 clones show significant induction, of which 37% have no hit or unknown function and the rest represent 661 genes with identified function. Similarly, out of 1452 clones showing significant reduction, only 53% of the clones have identified function and they represent 573 genes. The 661 induced genes are involved in 445 different molecular functions. About 90% of those functions were classified to 20 categories based on careful survey of the literature. Among other things, it appears that carbohydrate metabolism and mitochondrial function may be of central importance in the mechanism of dormancy release and studies in this direction are ongoing. Analysis of the reduced function is ongoing (Appendix A). A second set of hybridizations was carried out with RNA samples from buds exposed to short photoperiod, leading to induction of bud dormancy, and long photoperiod treatment, as control. Analysis indicated that 42 genes were significant difference between LD and SD and 11 of these were unique.

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Amir, Rachel, David J. Oliver, Gad Galili e Jacline V. Shanks. The Role of Cysteine Partitioning into Glutathione and Methionine Synthesis During Normal and Stress Conditions. United States Department of Agriculture, gennaio 2013. http://dx.doi.org/10.32747/2013.7699850.bard.

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The objective of this research is to study the nature of the competition for cysteine (Cys), the first organic sulfur-containing compound, between its two main metabolites, glutathione (GSH) and methionine (Met). GSH plays a central role in protecting plants during various stresses, while Met, an essential amino acid, regulates essential processes and metabolites in plant cells through its metabolite S-adenosyl-Met. Our results, which are based on flux analysis and measurements of Met- metabolites, show that the flux towards Met synthesis is high during non-stress conditions, however the flux is significantly reduced under stress conditions, when there is high synthesis of GSH. Under oxidative stress the expression level of the regulatory enzyme of Met synthesis, cystathionine g-synthase (CGS) was reduced. By using three different systems, we have found that that GSH down regulates the expression level of CGS, thus reducing Met synthesis. We have found that this regulation occurs at the post-transcriptional level, and further studies have shown that it occurs at post-translationaly. To reveal how oxidative stress affects the flux towards Met and GSH, flux analysis was performed. We have found that the level of Met is significantly reduced, while the level of glutathione significantly increases during stress. Under stress conditions most of the glutathione is converted from GSH to GSSG (the oxidised form of glutathione). These results suggest that under normal growth conditions, Cys is channelled towards both pathways to support GSH accumulation and the synthesis of growth-essential Met metabolites. However, during oxidative stress, when a high level of GSH is required to protect the plants, the levels of GSH increase while those of CGS are reduced. This reduction leaves more Cys available for GSH synthesis under stress conditions. In addition we have also studied the effects of high GSH level on the transcriptome profile. The analysis revealed that GSH affects the expression level of many major genes coding to enzymes or proteins associated with photosynthesis, starch degradation, hormone metabolism (especially genes associated with jasmonate), biotic stress (especially genes associated with PR-proteins), cytochrome P450 genes, regulation of transcription and signaling (especially genes associated with receptor kinases and calcium). These results suggest that indeed GSH levels affect different pathways and metabolites in plants.

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Surendra G, Dr Prasad, Dr Bhuyan Ashok K, Dr Baro Abhamon, Dr Saikia Uma K e Dr Kumar Angad. CLINICAL AND METABOLIC CHARACTERISTICS OF PRIMARY HYPERPARATHYROIDISM IN DIFFERENT AGE GROUPS- A TERTIARY CENTRE EXPERIENCE. World Wide Journals, febbraio 2023. http://dx.doi.org/10.36106/ijar/6005490.

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Background and Objectives- Symptomatic Primary Hyperparathyroidism (PHPT) is common in India in comparison to the western population. But there is very little data on the inuence of age on the presentation of PHPT. In the present study we aimed to analyse the clinical and metabolic prole among different age groups of symptomatic primary hyperparathyroidism. Methods: This retrospective analysis was done in PHPT patients who attended Department of Endocrinology, Gauhati Medical college and Hospital. Thirty-one PHPT subjects who presented to us over a period of last ve years were divided into three different age groups i.e, children and adolescents <18yrs, adults ≥18-50 years, and older group >50years. All major clinical, metabolic and imaging parameters were compared among these groups. Appropriate statistical methods were used to compare different variables. The age distribution ranged from 13 to Results: 72 years with mean age of 38.6±16.3years and with equal female to male ratio. Bony deformity (Rickets) as initial manifestation was seen in three adolescents and bone pain was common in adolescents(p=0.05). Prevalence of renal stones were higher in adult group(p=0.002), gastrointestinal manifestations were higher in older group (p=0.02). There was no signicant difference in fracture rate(P=0.17), brown tumours(P=0.56) and other symptoms among different age groups. Alkaline phosphatase(p=0.006) and iPTH(p=0.01) were signicantly higher in adolescent group. There was no signicant difference in serum calcium, phosphate, 25(OH)Vitamin-D3 and haemoglobin levels among different age groups. Age has substantial inuence on PHPT presentation. Bone Interpretation & Conclusion: pain and deformity was common in adolescents, while renal stones and gastrointestinal manifestations were common in middle aged and elderly group respectively

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Lurie, Susan, John Labavitch, Ruth Ben-Arie e Ken Shackel. Woolliness in Peaches and Nectarines. United States Department of Agriculture, 1995. http://dx.doi.org/10.32747/1995.7570557.bard.

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Abstract (sommario):

The overall goal of the research was to understand the processes involved in the development of woolliness in peaches and nectarines. Four specific hypotheses were proposed and in the course of the research evidence was gathered t support two of them and to not support two others. The hypotheses and a summary of the evidence are outlined below. 1. That woolliness arises from an imbalance between the activities of the cell wall pectin degrading enzymes. Using 'Flavortop' nectarines and 'Hermoza' peaches as model systems, storage regimes were manipulated to induce or prevent woolliness. The expression (mRNA abundance), protein content (Western blotting), and activity of polygalacturonase (PG) and pectin esterase (PE) were followed. Expression of the enzymes was not different, but activity and the ratio between PG and PE activities were quite different in fruits developing woolliness or ripening normally. This was also examined by looking at the substrate, the pectin moiety of the cell wall, and i woolly fruit there were more high molecular weight pectins with regions of non-methylated galacturonic acid residues. Taking an in vitro approach it was found a) that PE activity was stable at 0oC while PG activity decreased; b) incubating the calcium pectate fraction of the cell wall with PE extracted from peaches caused the polymers to form a gel characteristic of the visual woolly symptoms in peaches. 2. That continued cell wall synthesis occurs during storage and contributes to structural changes i cell walls and improper dissolution and softening after storage. We tried to adapt our technique of adding 13C-glucose to fruit discs, which was used successfully to follow cell wall synthesis during tomato ripening. However, the difference in sugar content between the two fruits (4% in tomato and 12% in peach) meant that the 13C-glucose was much more diluted within the general metabolite pool. We were unable to see any cell wall synthesis which meant that either the dilution factor was too great, or that synthesis was not occurring. 3. That controlled atmosphere (CA) prevents woolliness by lowering all enzyme activities. CA was found to greatly reduce mRNA abundance of the cell wall enzymes compared to regular air storage. However, their synthesis and activity recovered during ripening after CA storage and did not after regular air storage. Therefore, CA prevented the inhibition of enzyme activation found in regular air storage. 4. That changes in cell wall turgor and membrane function are important events in the development of woolliness. Using a micro pressure probe, turgor was measured in cells of individual 'O'Henry' and 'CalRed' peaches which were woolly or healthy. The relationship between firmness and turgor was the same in both fruit conditions. These data indicate that the development and expression of woolliness are not associated with differences in membrane function, at least with regard to the factors that determine cell turgor pressure. In addition, during the period of the grant additional areas were explored. Encoglucanase, and enzyme metabolizing hemicellulose, was found to be highly expressed air stored, but not in unstored or CA stored fruit. Activity gels showed higher activity in air stored fruit as well. This is the first indication that other components of the cell wall may be involved in woolliness. The role of ethylene in woolliness development was also investigated at it was found a) that woolly fruits had decreased ability to produce ethylene, b) storing fruits in the presence of ethylene delayed the appearance of woolliness. This latter finding has implication for an inexpensive strategy for storing peaches and nectarines.

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