Artículos de revistas: "Humour Vitrous"

1

Orii, Yusuke, Eriko Kunikane, Yutaka Yamada, Masakazu Morioka, Kentaro Iwasaki, Shogo Arimura, Akemi Mizuno y Masaru Inatani. "Brimonidine and timolol concentrations in the human vitreous and aqueous humors after topical instillation of a 0.1% brimonidine tartrate and 0.5% timolol fixed-combination ophthalmic solution: An interventional study". PLOS ONE 17, n.º 12 (1 de diciembre de 2022): e0277313. http://dx.doi.org/10.1371/journal.pone.0277313.

Texto completo

Resumen

Purpose To evaluate the concentrations of brimonidine and timolol in the vitreous and aqueous humors after instillation of a 0.1% brimonidine tartrate and 0.5% timolol fixed-combination ophthalmic solution. Methods This single-arm open-label interventional study included patients with macular holes or idiopathic epiretinal membranes who were scheduled for vitrectomy. Written informed consent was obtained from all participants. A 0.1% brimonidine tartrate and 0.5% timolol fixed-combination ophthalmic solution was administered topically twice daily for 1 week preoperatively. The vitreous and aqueous humors were sampled before vitrectomy, and brimonidine and timolol concentrations were quantified using liquid chromatography-tandem spectrometry. This study was registered with the Japan Registry of Clinical Trials (jRCT, ID jRCTs051200008; date of access and registration: April 28, 2020). The study protocol was approved by the University of Fukui Certified Review Board (CRB) and complied with the tenets of the Declaration of Helsinki. Results Eight eyes of eight patients (7 phakic eyes and 1 pseudophakic eye) were included in this study. The mean brimonidine concentrations in the vitreous and aqueous humors were 5.04 ± 4.08 nM and 324 ± 172 nM, respectively. Five of the eight patients had brimonidine concentrations >2 nM in the vitreous humor, which is necessary to activate α2 receptors. The mean timolol concentrations in the vitreous and aqueous humors were 65.6 ± 56.0 nM and 3,160 ± 1,570 nM, respectively. Brimonidine concentrations showed significant positive correlations with timolol concentrations in the vitreous humor (P < 0.0001, R2 = 0.97) and aqueous humor (P < 0.0001, R2 = 0.96). Conclusions The majority of patients who received a 0.1% brimonidine tartrate and 0.5% timolol topical fixed-combination ophthalmic solution showed a brimonidine concentration >2 nM in the vitreous humor. Brimonidine and timolol may be distributed in the ocular tissues through an identical pathway after topical instillation.

Los estilos APA, Harvard, Vancouver, ISO, etc.

2

Mochizuki, Kiyofumi, Akira Sawada, Shinsuke Suemori, Hideaki Kawakami, Yoshiaki Niwa, Yuji Kondo, Kiyofumi Ohkusu et al. "Intraocular Penetration of Intravenous Micafungin in Inflamed Human Eyes". Antimicrobial Agents and Chemotherapy 57, n.º 8 (20 de mayo de 2013): 4027–30. http://dx.doi.org/10.1128/aac.02300-12.

Texto completo

Resumen

ABSTRACTEight eyes of 7 patients with fungal disease received intravenous injections of 150 to 300 mg micafungin, and samples of blood, cornea, retina-choroid, aqueous humor, and vitreous humor were collected. The micafungin levels in all collected samples exceeded the MICs; however, the levels in the vitreous and aqueous humors were lower. Our findings suggest that intravenous micafungin should be given in combination with intravitreal antifungal agents after vitrectomy in severe cases of intraocular fungal diseases.

Los estilos APA, Harvard, Vancouver, ISO, etc.

3

Semoun, Oudy, Sandrine Marchand, Nicolas Grégoire, Isabelle Lamarche, Christophe Adier, Laurent Laroche, Pablo Goldschmidt y William Couet. "Modeling Approach To Characterize Intraocular Doripenem Pharmacokinetics after Intravenous Administration to Rabbits, with Tentative Extrapolation to Humans". Antimicrobial Agents and Chemotherapy 56, n.º 7 (23 de abril de 2012): 3531–34. http://dx.doi.org/10.1128/aac.06329-11.

Texto completo

Resumen

ABSTRACTThe aim of this study was to determine the penetration of doripenem administered intravenously into the rabbit aqueous and vitreous humors. Nineteen New Zealand White rabbits received a 20-mg dose of doripenem intravenously over 60 min. Specimens of aqueous humor, vitreous humor, and blood were obtained 30 min (n= 5), 1 h (n= 5), 2 h (n= 5), and 3 h (n= 4) after the beginning of the infusion and analyzed by high-performance liquid chromatography (HPLC). A pharmacokinetic (PK) model was developed to fit the experimental data. Doripenem concentrations in aqueous humor were lower than those in plasma ultrafiltrates at all sampling times, with an average aqueous humor-to-plasma ultrafiltrate area under the concentration-time curve ratio estimated as 8.3%. A pharmacokinetic model with peripheral elimination described the data adequately and was tentatively used to predict concentration-versus-time profiles and pharmacokinetic-pharmacodynamic (PK-PD) target attainment in patients under various dosing regimens. In conclusion, systematically administered doripenem does not seem to be a promising approach for the treatment of intraocular infections, especially since it could not be detected in the vitreous humor. However, this study has provided an opportunity to develop a new PK modeling approach to characterize the intraocular distribution of doripenem administered intravenously to rabbits, with tentative extrapolation to humans.

Los estilos APA, Harvard, Vancouver, ISO, etc.

4

Piette, M. "The Effect of the Post-Mortem Interval on the Level of Creatine in Vitreous Humour". Medicine, Science and the Law 29, n.º 1 (enero de 1989): 47–54. http://dx.doi.org/10.1177/002580248902900107.

Texto completo

Resumen

By means of 103 medico-legal autopsies it was established that a rise in the creatine level occurs in the vitreous humour after death. In view of the satisfactory correlation between the post-mortem interval and the creatine level in the vitreous humour (r = 0.84, p < 0.001) investigations were undertaken as to whether the creatine level in vitreous humour can serve in current medico-legal practice as an indication for the post-mortem interval, especially for the later period (more than three days). On balance this creatine determination is only useful when combined with all other medico-legal parameters that establish the time of death, remembering that the confidence-interval in the investigations was rather wide.

Los estilos APA, Harvard, Vancouver, ISO, etc.

5

Silva, Andreia F., Manuel A. Alves y Mónica S. N. Oliveira. "Rheological behaviour of vitreous humour". Rheologica Acta 56, n.º 4 (7 de febrero de 2017): 377–86. http://dx.doi.org/10.1007/s00397-017-0997-0.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

6

Bergandi, Loredana, Oleksii A. Skorokhod, Rosalba La Grotta, Evelin Schwarzer y Raffaele Nuzzi. "Oxidative Stress, Lipid Peroxidation, and Loss of Hyaluronic Acid in the Human Vitreous Affected by Synchysis Scintillans". Journal of Ophthalmology 2019 (30 de octubre de 2019): 1–8. http://dx.doi.org/10.1155/2019/7231015.

Texto completo

Resumen

The aim of this study was to assess the oxidative stress status in eyes affected by synchysis scintillans and to compare it to vitreoretinal disorders without synchysis scintillans. Human aqueous and vitreous humors were obtained during vitrectomy from thirty-seven otherwise healthy patients that were randomly chosen among patients that had to undergo a 25-gauge pars plana vitrectomy from the central vitreous cavity, for either synchysis scintillans (n = 16) or vitreoretinal disorders without synchysis scintillans (n = 21), such as idiopathic epimacular membrane (n = 12), macular hole (n = 5), or rhegmatogenous retinal detachment (n = 4). The redox parameters thiobarbituric acid reactive substances (TBARS), a measurement of lipid peroxidation, nitrite concentration, an estimate of nitric oxide (NO) production, 4-hydroxynonenal (4-HNE)-protein conjugates, a structural protein modification by lipid peroxidation product 4-HNE, and the antioxidative activities of Cu,Zn-superoxide dismutase (SOD), and catalase were measured in aqueous and vitreous humors and compared between synchysis scintillans affected and not-affected patients. TBARS and nitrite levels of the vitreous humor were significantly higher in patients with synchysis scintillans as compared to patients affected by vitreoretinal disorders without synchysis scintillans. Synchysis scintillans patients had significantly lower activities of SOD and catalase both in aqueous and vitreous humors than patients with vitreoretinal disorders without synchysis. The consequently higher lipoperoxide-dependent 4-HNE production in synchysis scintillans was detectable in aqueous and vitreous humors as a significant increased accumulation of 4-HNE-protein conjugates vs nonsynchysis vitreoretinal disorders. Additionally, hyaluronic acid (HA) was significantly decreased in the vitreous body of synchysis scintillans patients. The data consistently show that synchisis scintillans is accompanied by a redox imbalance with increased oxidative modifications of 4-HNE proteins and loss of HA, both of likely importance for remote damages of the retina. It remains to be proven whether a therapeutic strategy which targets oxidative stress may be effective in the treatment of synchysis patients.

Los estilos APA, Harvard, Vancouver, ISO, etc.

7

Bennett, Michael J., Marie C. Ragni, Ian Hood y Daniel E. Hale. "Comparison of Post-Mortem Urinary and Vitreous Humour Organic Acids". Annals of Clinical Biochemistry: International Journal of Laboratory Medicine 29, n.º 5 (septiembre de 1992): 541–45. http://dx.doi.org/10.1177/000456329202900509.

Texto completo

Resumen

We have analysed organic acid profiles in 74 samples of post-mortem vitreous humour from the suddent infant death syndrome and compared the profiles to those obtained from the corresponding urine or bladder wall swab. There was a high degree of correlation indicating that vitreous humour analysis in high-risk infants is an appropriate analytical strategy when urine is not available. In our patient sample two infants had evidence of abnormal methylmalonic acid metabolism, one had glyceric aciduria (and elevated levels of vitreous humour glyceric acid), one had evidence of pre-existing liver damage as judged by the presence of 4-hydroxyphenyllactic acid, one had a non-ketotic dicarboxylic aciduria indicating inhibited fatty acid oxidation and two patients had significant long-chain 3-hydroxydicarboxylic acids and evidence of paracetamol ingestion.

Los estilos APA, Harvard, Vancouver, ISO, etc.

8

Yip, David C. P. "Vitreous humor alcohol". Forensic Science International 73, n.º 2 (mayo de 1995): 155. http://dx.doi.org/10.1016/0379-0738(95)01727-z.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

9

ABDELKAWI, SALWA A. "THE RHEOLOGICAL PROPERTIES OF VITREOUS HUMOR AFTER Q-SWITCHED Nd:YAG LASER PHOTO DISRUPTION". Biophysical Reviews and Letters 07, n.º 01n02 (junio de 2012): 29–39. http://dx.doi.org/10.1142/s179304801250004x.

Texto completo

Resumen

This work aimed to study the photo disruptive effect of a Q-switched Nd:YAG laser with two different energy protocols on the rheological properties of the vitreous humor after treatment of posterior vitreous detachment (PVD). Twenty-one New Zealand albino rabbits were used in this study and divided into three groups. One group was used as control (n = 6 eyes), the second group (n = 18) was treated with Q-switched Nd:YAG laser energy of 5 mJ × 100 pulse (× means times) delivered to the anterior, middle and posterior vitreous respectively (n = 6 eyes for each). The third group (n = 18 eyes) was treated with 10 mJ × 50 pulse delivered to the anterior, middle and posterior vitreous respectively (n = 6 eyes for each). After two weeks, the protein content, refractive index (RI) and the rheological properties of vitreous humor were determined. The protein content, refractive index, consistency, shear stress and viscosity were increased especially for irradiation of the mid-vitreous, and posterior vitreous. The flow index remained below unity indicating the non-Newtonian behavior of the vitreous humor. Application of Q-switched Nd:YAG laser on mid-vitreous and posterior vitreous induce deleterious effect on the gel state of the vitreous humor.

Los estilos APA, Harvard, Vancouver, ISO, etc.

10

Lutty, G. A., R. J. Mello, C. Chandler, C. Fait, A. Bennett y A. Patz. "Regulation of cell growth by vitreous humour". Journal of Cell Science 76, n.º 1 (1 de junio de 1985): 53–65. http://dx.doi.org/10.1242/jcs.76.1.53.

Texto completo

Resumen

Extracts of normal vitreous have been found to inhibit angiogenesis in two animal models: tumour-induced neovascularization in the rabbit corneal micropocket and retinal extract-induced angiogenesis in the chick chorioallantoic membrane assay. Using in vitro assays, we have found recently that an extract of bovine vitreous, free of hyaluronic acid, inhibits proliferation of cells in the aortic wall, i.e. endothelium and smooth muscle cells, as well as capillary and corneal endothelium. The inhibition is dose-dependent, as determined by either cell count or [3H]thymidine incorporation, and not due to cytotoxicity, as demonstrated with a double-label thymidine assay. The inhibitor is trypsin-sensitive and heat-stable (95 degrees C for 10 min). Conversely, proliferation of pericytes, lens epithelium and fibroblasts (dermal and corneal) was stimulated by the vitreous extract. This mitogenic activity was heat-labile. Growth of pigment epithelium and several tumour cell lines was unaffected. The data demonstrate that normal vitreous contains a heat-stable growth inhibitor specific for endothelium and smooth muscle cells, and a non-specific heat-labile mitogen. The paradoxical effect of this antiangiogenic factor on arterial and capillary contractile cells, smooth muscle and pericytes, suggests a basic difference in the regulation of the two vasculatures. The results suggest that a substance in normal vitreous may be important in controlling neovascularization that results from diabetic and other retinopathies, and could be useful for inhibiting tumour-induced angiogenesis.

Los estilos APA, Harvard, Vancouver, ISO, etc.

11

Liu, Weiguo, Qing Feng Liu, Ruth Perkins, George Drusano, Arnold Louie, Assumpta Madu, Umar Mian, Martin Mayers y Michael H. Miller. "Pharmacokinetics of Sparfloxacin in the Serum and Vitreous Humor of Rabbits: Physicochemical Properties That Regulate Penetration of Quinolone Antimicrobials". Antimicrobial Agents and Chemotherapy 42, n.º 6 (1 de junio de 1998): 1417–23. http://dx.doi.org/10.1128/aac.42.6.1417.

Texto completo

Resumen

ABSTRACT We have used a recently described animal model to characterize the ocular pharmacokinetics of sparfloxacin in vitreous humor of uninfected albino rabbits following systemic administration and direct intraocular injection. The relationships of lipophilicity, protein binding, and molecular weight to the penetration and elimination of sparfloxacin were compared to those of ciprofloxacin, fleroxacin, and ofloxacin. To determine whether elimination was active, elimination rates following direct injection with and without probenecid or heat-killed bacteria were compared. Sparfloxacin concentrations were measured in the serum and vitreous humor by a biological assay. Protein binding and lipophilicity were determined, respectively, by ultrafiltration and oil-water partitioning. Pharmacokinetic parameters were characterized with RSTRIP, an iterative, nonlinear, weighted, least-squares-regression program. The relationship between each independent variable and mean quinolone concentration or elimination rate in the vitreous humor was determined by multiple linear regression. The mean concentration of sparfloxacin in the vitreous humor was 59.4% ± 12.2% of that in serum. Penetration of sparfloxacin, ciprofloxacin, fleroxacin, and ofloxacin into, and elimination from, the vitreous humor correlated with lipophilicity (r 2 > 0.999). The linear-regression equation describing this relationship was not improved by including the inverse of the square root of the molecular weight and/or the degree of protein binding. Elimination rates for each quinolone were decreased by the intraocular administration of probenecid. Heat-killedStaphylococcus epidermidis decreased the rate of elimination of fleroxacin. Penetration of sparfloxacin into the noninflamed vitreous humor was greater than that of any quinolone previously examined. There was an excellent correlation between lipophilicity and vitreous entry or elimination for sparfloxacin as well as ciprofloxacin, fleroxacin, and ofloxacin. There are two modes of quinolone translocation into and out of the vitreous humor: diffusion into the eye and both diffusion and carrier-mediated elimination out of the vitreous humor.

Los estilos APA, Harvard, Vancouver, ISO, etc.

12

González-Montaña, José-Ramiro, Francisco Escalera-Valente, Marta E. Alonso, Juan M. Lomillos y Vicente Gaudioso. "Relationships Between Concentrations of Biological Variables in Eye Fluids and Blood After Exercise in Lidia Cattle". Acta Veterinaria 68, n.º 4 (1 de diciembre de 2018): 420–33. http://dx.doi.org/10.2478/acve-2018-0034.

Texto completo

Resumen

Abstract Lidia cattle are a heterogeneous Iberian cattle population known for its natural aggressiveness and resistance to traditional handling procedures making in vivo blood sampling and biological fluid collections extremely difficult. Blood variables are influenced by physical exertion and stressful situations; consequently, post-mortem blood analysis does not reflect basal concentrations for this species. Nevertheless, ocular fluids (aqueous and vitreous humour) maintain their stable composition after death and maybe could be used to estimate ante-mortem blood concentrations. So, 15 bulls which had fought (for 15-20 minutes) and, subsequently after death, blood, aqueous and vitreous humour were sampled. Total protein, albumin, triglycerides, uric acid, urea, AST, ALT, GGT, AP, CK, LDH, cholesterol, creatinine, glucose and lactate were measured. Statistical analysis and correlation coefficients between the three fluids were carried out. All variables showed high plasma concentrations of glucose, uric acid, LDH and CK, compared with normal bovine concentrations. Apart from urea, all plasma concentrations were greater than those found in ocular fluids. The measured enzymes activities were higher in the vitreous than in the aqueous humour, but only marked differences in uric acid, lactate, AP and AST were found. There was a significant correlation between creatinine in the plasma and aqueous humour, and between albumin and GGT in the plasma and vitreous humour. Glucose, creatinine and urea exhibit a high correlation between ocular fluids. All plasma concentrations were clearly modified, however ocular fluids do not seem affected, thus establishing important correlations between the blood and intraocular fluids.

Los estilos APA, Harvard, Vancouver, ISO, etc.

13

Hood, C., P.-Y. Daoust, J. Lien y C. Richter. "An experimental study of postmortem ocular fluid and core temperature analysis in incidentally captured harbour porpoise (Phocoena phocoena)". NAMMCO Scientific Publications 5 (1 de julio de 2003): 229. http://dx.doi.org/10.7557/3.2750.

Texto completo

Resumen

Determination of elapsed time since death in small cetaceans can be important to our understanding of the nature of their interactions with fishing operations. This pilot study was conducted to determine the potential diagnostic usefulness of ocular fluid (vitreous humour) and core body temperature to estimate postmortem intervals in harbour porpoises (Phocoena phocoena). Core temperature and concentrations of various constituents of vitreous humour (glucose, urea, sodium, potassium, chloride, magnesium, calcium, and phosphorus) were determined in 24 harbour porpoises incidentally caught in groundfish gillnets in the waters of the Gulf of Maine and the Bay of Fundy. These parameters were compared to published values for rectal temperatures and the serum concentrations of several selected elements in live harbour porpoises. Glucose in vitreous humour decreased in dead animals compared to serum values in live ones; its level was positively correlated with core temperature. Potassium and magnesium in vitreous humour increased following death. These data suggest that most animals analysed had been dead for several hours. For the present, the methodology affords researchers an approach that appears to hold some promise. However, the most practical technique requires testing animals with a known time of death in order to derive a set of curves for ocular fluid values and temperature versus time that are appropriate for a statistical presentation of predictability for the time since death.

Los estilos APA, Harvard, Vancouver, ISO, etc.

14

De Martinis, B. S., C. MC de Paula, A. Braga, H. T. Moreira y C. CS Martin. "Alcohol distribution in different postmortem body fluids". Human & Experimental Toxicology 25, n.º 2 (febrero de 2006): 93–97. http://dx.doi.org/10.1191/0960327106ht596oa.

Texto completo

Resumen

Aims: The determination of postmortem ethanol is one of the most frequently requested analyses in forensic toxicology and of extreme importance, especially when the concentration is found to be above the legal level for intoxication at one sampling site and below that level at another sampling site. Because of the unavailability of blood samples for toxicological analysis or even contaminated samples, there is an enormous effort to find alternative sampling sites, such as vitreous humor for ethanol analysis. The main purpose of this study was to establish correlations between urine and blood alcohol concentrations collected from different sites and vitreous humor. Methods: Ethanol concentrations were determined in specimens of heart, subclavian and femoral blood, urine and vitreous humor, collected from 21 cadavers who were victims of different causes of death. Determinations of ethanol were performed in duplicate using capillary gas chromatography/flame ionization detector and headspace techniques. Results: Statistical analysis of the results indicated that there were no significant differences among urine and blood samples collected from different sites compared to vitreous humor. Regarding vitreous humor ethanol concentration, Pearson's correlation coefficient was 0.97 for femoral blood and urine, 0.96 for heart blood and 0.94 for subclavian blood. The results demonstrated that all the fluids tested against vitreous humor significantly correlated with P (associated probability for the used correlation tests) B<0.05. Conclusions: Vitreous humor can be considered as an alternative sample to urine and blood specimens.

Los estilos APA, Harvard, Vancouver, ISO, etc.

15

Angi, Martina, Helen Kalirai, Sarah E. Coupland, Bertil E. Damato, Francesco Semeraro y Mario R. Romano. "Proteomic Analyses of the Vitreous Humour". Mediators of Inflammation 2012 (2012): 1–7. http://dx.doi.org/10.1155/2012/148039.

Texto completo

Resumen

The human vitreous humour (VH) is a transparent, highly hydrated gel, which occupies the posterior segment of the eye between the lens and the retina. Physiological and pathological conditions of the retina are reflected in the protein composition of the VH, which can be sampled as part of routine surgical procedures. Historically, many studies have investigated levels of individual proteins in VH from healthy and diseased eyes. In the last decade, proteomics analyses have been performed to characterise the proteome of the human VH and explore networks of functionally related proteins, providing insight into the aetiology of diabetic retinopathy and proliferative vitreoretinopathy. Recent proteomic studies on the VH from animal models of autoimmune uveitis have identified new signalling pathways associated to autoimmune triggers and intravitreal inflammation. This paper aims to guide biological scientists through the different proteomic techniques that have been used to analyse the VH and present future perspectives for the study of intravitreal inflammation using proteomic analyses.

Los estilos APA, Harvard, Vancouver, ISO, etc.

16

Holstein, Andreas, Ulf Titze y Cornelius Hess. "Postmortem Analysis of Vitreous Humor For Detection of Antemortem Disorders in Glucose Metabolism. An Old Method Revisited". Experimental and Clinical Endocrinology & Diabetes 128, n.º 04 (19 de octubre de 2018): 239–43. http://dx.doi.org/10.1055/a-0752-0028.

Texto completo

Resumen

AbstractIt has been estimated that 15% up to one third of cases of deaths due to diabetic ketoacidosis occur in individuals with so far unknown diabetes. Moreover, cardiac arrhythmias that occur during nocturnal hypoglycaemia include bradycardia and ectopics that may provoke lethal arrhythmias. As postmortem capillary glucose concentrations have no diagnostic value, the postmortem forensic proof of hyperglycaemia or hypoglycaemia remains a challenge. The established but rarely applied method of postmortem determination of glucose and lactate in vitreous humor with or without calculation of the sum formula of Traub could provide reliable exclusion or proof of severe antemortem disorders in glucose metabolism. To date, diagnostic puncture of vitreous humor is more established for the postmortem detection of diabetic ketoacidosis than for the exclusion or proof of lethal hypoglycaemia. Vitreous humor is protected from postmortem degradation and contamination due to its isolated localization. The autolytic process in vitreous humor is considerably delayed compared to blood or liquor. In vitreous humor also the triggering agent of hypoglycaemia (insulin, insulin analogues) is easier to be detected than in blood since insulins are very unstable in postmortem blood. Furthermore, parameters of long term glycaemic control such as 1,5-anhydroglucitol, HbA1c and fructosamine can be determined in vitreous humor. However, limitations and interference factors of this method should be carefully considered. So far, clinical diabetology has taken no broad notice of this useful forensic procedure.

Los estilos APA, Harvard, Vancouver, ISO, etc.

17

Meskauskas, Julia, Rodolfo Repetto y Jennifer H. Siggers. "Oscillatory motion of a viscoelastic fluid within a spherical cavity". Journal of Fluid Mechanics 685 (21 de septiembre de 2011): 1–22. http://dx.doi.org/10.1017/jfm.2011.263.

Texto completo

Resumen

AbstractWe study the motion of a viscoelastic fluid within a rigid spherical cavity with the aim of improving understanding of the motion of the vitreous humour in the human eye. The flow of vitreous humour leads to traction on the retina, which, once the retina is torn or damaged, can cause it to detach from the choroid, leading to loss of sight if left untreated. In the first part of the paper we investigate the relaxation behaviour of the fluid, the transient flow that would be observed in the stationary sphere starting from non-stationary initial conditions. For a general viscoelastic fluid we calculate the growth rates and eigenfunctions associated with the system, and we discuss two particular rheological models of the vitreous humour taken from the literature. In the second part of the paper we consider forced oscillations of the fluid, due to small-amplitude rotations of the sphere about a diameter, representing saccades of the eyeball. We conclude with a discussion of the possible occurrence of resonant phenomena and their clinical relevance.

Los estilos APA, Harvard, Vancouver, ISO, etc.

18

Obuchowska, I., A. Stankiewicz y Z. Mariak. "Cathepsin A activity of normal bovine ocular tissues and pathological human intraocular fluids." Acta Biochimica Polonica 43, n.º 4 (31 de diciembre de 1996): 687–92. http://dx.doi.org/10.18388/abp.1996_4465.

Texto completo

Resumen

Cathepsin A activity assayed with N-Cbz-Phe-Ala, N-Cbz-Glu-Tyr and N-Cbz-Glu-Phe as substrates, was measured in fresh corneas, lenses, aqueous humor, vitreous humor and choroid plus retinal pigment epithelium taken from normal bovine eye balls and in human intraocular fluids from the eye balls in various ocular diseases (cataract, glaucoma, diabetes, intraocular tumors). Cathepsin A exhibited a pH optimum at 5.0 and showed the highest specificity towards N-Cbz-Phe-Ala as a substrate. In bovine ocular tissues high cathepsin A activity was found in the choroid plus retinal pigment epithelium and in cornea. The lens and the vitreous humor showed low enzyme activity and the aqueous humor none at all. In the human aqueous humor of the eye with cataract cathepsin A activity was more than three times higher then in the eye with choroid tumor. In human vitreous humor in absolute glaucoma the activity was twice as high as in melanoma and almost three times higher than in the case of lung metastatic tumor. Diabetes in glaucoma increased seven fold cathepsin A activity in the vitreous humor.

Los estilos APA, Harvard, Vancouver, ISO, etc.

19

Mulla, Amith, K. Lorne Massey y Jawahar Kalra. "Vitreous Humor Biochemical Constituents". American Journal of Forensic Medicine & Pathology 26, n.º 2 (junio de 2005): 146–49. http://dx.doi.org/10.1097/01.paf.0000164001.50097.4c.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

20

Yang, C., H. Notbohm, Y. Açil, R. Heifeng, S. Bierbaum y P. K. Müller. "In vitro fibrillogenesis of collagen II from pig vitreous humour". Biochemical Journal 306, n.º 3 (15 de marzo de 1995): 871–75. http://dx.doi.org/10.1042/bj3060871.

Texto completo

Resumen

Collagen from pig vitreous humour was fractionated into a soluble and an insoluble fraction by centrifugation. Most of the collagen II in the soluble fraction was present as pN-collagen II (procollagen II without the C-terminal propeptide), besides smaller quantities of procollagen II, collagen II and two as yet unidentified alpha-chains of collagen II. Other collagen types may be present only in trace amounts. Collagen II of the insoluble fraction, which is mostly deposited in fibrillar aggregates, consists of both pN-collagen II and collagen II. To determine the possible role of collagen II precursors in the formation of the extracellular matrix of the vitreous humour these collagen molecules were purified and in vitro fibrillogenesis was used to demonstrate that pN-collagen II could form fibrils in mixtures with collagen II. These fibrils have a reduced mass per unit length depending on the content of pN-collagen in the mixture. Cross-sections of the newly formed fibrillar aggregates revealed a flattened shape. The incomplete processing of the precursors of collagen II may be part of regulatory mechanisms possibly controlling the formation of a translucent scaffold as is required in the vitreous humour.

Los estilos APA, Harvard, Vancouver, ISO, etc.

21

Терёхина, N. Terekhina, Акимов y Pavel Akimov. "Biochemical Analysis of Vitreous Humor in Postmortal Diagnosis of Renal Failure". Journal of New Medical Technologies 20, n.º 4 (20 de diciembre de 2013): 47–49. http://dx.doi.org/10.12737/2726.

Texto completo

Resumen

The content of medium molecular weight peptides and creatinine in serum and vitreous humor from 48 corpses of people suffering from diabetes mellitus during his lifetime and 27 without this disease, formed the control group, were investigated. The presence of renal failure among patients with diabetes mellitus and in the control group was, respectively, in 20 and 15 persons was revealed. The content of serum creatinine in cadaver blood without renal failure was more than 2-2,5 - folds in comparative with living people and was not more than 240 μηΊθΙ/L. The content of serum medium molecular weight peptides in control group was not more than 2,8 g/L, and in the group of diabetes mellitus without renal failure - 2,9 g/L. The obtained results are analogical with data of living people accordingly literature sources. Direct correlation between the content of creatinine, medium molecular weight peptides and vitreous humor and serum are estimated. The maximum content of creatinine and medium molecular weight peptides in vitreous humor were, respectively, 110 μΓηοΙ/L and 0,5 g/L. The values extreme graduated in presents of renal failure as in serum, as in vitreous humor. Thus, in postmortal period appropriate to determine the vitreous humor creatinine and medium molecular weight peptides content for the diagnosis of renal failure.

Los estilos APA, Harvard, Vancouver, ISO, etc.

22

Parsons, M. A. "Concurrent vitreous disease may produce abnormal vitreous humour biochemistry and toxicology". Journal of Clinical Pathology 56, n.º 9 (1 de septiembre de 2003): 720—a—720. http://dx.doi.org/10.1136/jcp.56.9.720-a.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

23

Balaiya, Sankarathi, Zimei Zhou y Kakarla V. Chalam. "Characterization of Vitreous and Aqueous Proteome in Humans With Proliferative Diabetic Retinopathy and Its Clinical Correlation". Proteomics Insights 8 (1 de enero de 2017): 117864181668607. http://dx.doi.org/10.1177/1178641816686078.

Texto completo

Resumen

Aims: Proliferative diabetic retinopathy (PDR) is associated with microvascular complications that cause biochemical changes in the human retina and alter the proteome of vitreous humor and aqueous humor (AH). Methods: Human vitreous humor and AH of PDR subjects were collected. Subjects who had surgery for epiretinal membrane or macular hole served as controls. Protein profiles were obtained and analyzed after running the samples on a liquid chromatography-mass spectrometry/mass spectrometry. Results: In vitreous humor, 16 unique proteins were noted in PDR patients, but not in controls. Those were associated mainly with coagulation, complement, and kallikrein-kinin systems. Under coagulation, fibrinogen and prothrombin proteins were more evident and may emphasize the importance of angiogenesis in the development of PDR. Vitreous proteins showed replicative presence in AH too. As for AH samples, we detected 10 proteins found in PDR patients, which were related to transport, coagulation, and inflammatory responses. Conclusions: We found 57 proteins in human vitreous and 39 proteins in AH. Identification of these proteins that are involved in various pathways will be helpful to understand diabetic retinopathy pathogenesis and to develop proteome as a biomarker for PDR.

Los estilos APA, Harvard, Vancouver, ISO, etc.

24

López-Cortés, Luis F., R. Ruiz-Valderas, M. J. Lucero-Muñoz, E. Cordero, M. T. Pastor-Ramos y J. Marquez. "Intravitreal, Retinal, and Central Nervous System Foscarnet Concentrations after Rapid Intravenous Administration to Rabbits". Antimicrobial Agents and Chemotherapy 44, n.º 3 (1 de marzo de 2000): 756–59. http://dx.doi.org/10.1128/aac.44.3.756-759.2000.

Texto completo

Resumen

ABSTRACT Retinal, vitreous humor, brain, and cerebrospinal fluid (CSF) foscarnet levels were measured by high-performance liquid chromatography after administration of an intravenous dose of 120 mg/kg of body weight to 32 pigmented rabbits. A pharmacokinetic analysis was done using a two-compartment model. The penetration ratios, defined as ratios of retinal, vitreous humor, brain, and CSF areas under the concentration-time curve from 0 to 2 h were 110% ± 1%, 12.3% ± 0.7%, 118% ± 1%, and 20.2% ± 2.2%, respectively. These results suggest a good penetration of foscarnet into the retinal and brain tissues, reaching higher concentrations than those estimated from vitreous humor and CSF levels.

Los estilos APA, Harvard, Vancouver, ISO, etc.

25

Livermore, J. L., T. W. Felton, J. Abbott, A. Sharp, J. Goodwin, L. Gregson, P. A. Warn, S. J. Howard y W. W. Hope. "Pharmacokinetics and Pharmacodynamics of Anidulafungin for Experimental Candida Endophthalmitis: Insights into the Utility of Echinocandins for Treatment of a Potentially Sight-Threatening Infection". Antimicrobial Agents and Chemotherapy 57, n.º 1 (31 de octubre de 2012): 281–88. http://dx.doi.org/10.1128/aac.01387-12.

Texto completo

Resumen

ABSTRACTCandidachorioretinitis and endophthalmitis are relatively common manifestations of disseminated candidiasis. Anidulafungin is increasingly used for the treatment of disseminated candidiasis, but its efficacy forCandidaendophthalmitis is not known. A nonneutropenic model of hematogenousCandidaendophthalmitis was used. Anidulafungin at 5, 10, and 20 mg/kg was initiated at 48 h postinoculation. The fungal densities in the kidney and vitreous humor were determined. Anidulafungin concentrations in the plasma and vitreous humor were measured using high-performance liquid chromatography (HPLC). A pharmacokinetic-pharmacodynamic model was used to link anidulafungin concentrations with the observed antifungal effect. The area under the concentration-time curve (AUC) associated with stasis was determined in the both the kidney and the vitreous humor. The results were bridged to humans to identify likely dosages that are associated with significant antifungal activity within the eye. Inoculation ofCandida albicansresulted in logarithmic growth in both the vitreous humor and the kidney. The pharmacokinetics of anidulafungin were linear. There was dose-dependent penetration of the anidulafungin into the vitreous humor. The exposure-response relationships in the kidney and vitreous were completely discordant. AUCs of 270 and 100 were required for stasis in the eye and kidney, respectively. The currently licensed regimen results in an AUC for an average patient that is associated with stasis in the kidney but minimal antifungal activity in the eye. We conclude that anidulafungin penetrates the eye in a dose-dependent manner and that dosages higher than those currently licensed are required to achieve significant antifungal activity in the eye.

Los estilos APA, Harvard, Vancouver, ISO, etc.

26

Hu, Xiao-Feng, Hao Kang, Hui Wang, Xu-Hui Liu y Yong Tao. "Clinical characteristics of ocular toxocariasis in adults in north China". International Journal of Ophthalmology 15, n.º 3 (18 de marzo de 2022): 401–6. http://dx.doi.org/10.18240/ijo.2022.03.05.

Texto completo

Resumen

AIM: To investigate the clinical features of adult patients with ocular toxocariasis (OT) in north China and to diagnose adults OT patients in early stage. METHODS: Clinical data of 24 adults with OT were retrospectively analyzed. Slit lamp photographs and fundus photographs and other imaging examinations of all the patients were reviewed. A questionnaire concerning the pet ownership and place of residence was completed to investigate the possible infection origin. Descriptive statistical analyses were performed on the demographic data, clinical features, funduscopic findings and ELISA results. RESULTS: Among the 24 patients diagnosed with OT by Toxocara IgG antibody in intraocular fluid, 16 (66.7%) eyes were right eye. The onset age of 12 eyes (50.0%) was between 30 and 40 years old, and 21 (87.5%) eyes were of peripheral granuloma type. The most common sign was vitreous opacity. Granulomas were detected in all the eyes, and 20 (83.3%) patients resided in rural area. In 4 patients, the concentration of anti-Toxocara antibody both in anterior humor and in vitreous humor were detected, and the results showed the concentration in vitreous humor was much higher than aqueous humor. CONCLUSION: Our study analyzes the clinical manifestation of OT in adults, which may have been under-recognized before. Eye side, residence, and detection of granuloma may help us in diagnosis of OT in patients with monocular vitreous opacity. For adult patients with presumed OT, negative results of anti-Toxocara antibody in anterior humor cannot rule out the possibility of OT, further detection of vitreous humor is suggested for final diagnosis.

Los estilos APA, Harvard, Vancouver, ISO, etc.

27

Tabatabaei, Seyed Ali, Kazhaal Sheikhi, Reza Ghaffari, Mohammad Soleimani, Mansoor Shahriari, Kosar Esmaili, Sara Hobaby y Kasra Cheraqpour. "Microbiological study on foreign body and vitreous samples of patients with intraocular foreign body". Journal of International Medical Research 50, n.º 12 (diciembre de 2022): 030006052211384. http://dx.doi.org/10.1177/03000605221138482.

Texto completo

Resumen

Objective To evaluate the relationship between the microbiological results of the vitreous humor and those of foreign body specimens in patients with intraocular foreign body (IOFB). Methods Seventy-one patients with an IOFB were included in this descriptive prospective case series. All patients underwent immediate IOFB removal. Vitreous sampling was performed during vitrectomy. Foreign bodies were placed directly into culture media for microbiological study. Results Thirteen (18.3%) patients developed endophthalmitis. The results of microbiological analysis of IOFB and vitreous humor specimens were negative in nine patients and positive in four. Fifty-eight (81.6%) patients with an IOFB had no evidence of endophthalmitis. Among them, seven patients showed positive microbiological results of foreign bodies with no manifestations of endophthalmitis. In five patients, a Staphylococcus epidermidis strain was observed in the culture of the IOFB specimen. Two patients had only positive smear test results of their vitreous humor specimen. Conclusion A correlation appears to be present between the microbiological results of the vitreous humor and IOFB specimens in patients with clinical findings of endophthalmitis but not in patients with a pure IOFB without clinical features of endophthalmitis. This may justify early use of intravitreal and intravenous antibiotics before the development of endophthalmitis.

Los estilos APA, Harvard, Vancouver, ISO, etc.

28

Putienko, A. A. y D. N. Pogorely. "Blood and vitreous humor cytokine profile in patients with proliferative diabetic retinopathy and post-vitrectomy hemophthalmia". Kazan medical journal 94, n.º 1 (15 de febrero de 2013): 26–30. http://dx.doi.org/10.17816/kmj1764.

Texto completo

Resumen

Aim. To study vascular endothelial growth factor (VEGF), tumor necrosis factor alpha (TNF-α), interleukin-1β (IL-1β) and interleukin-1 receptor antagonist (IL-1RA) blood and vitreous humor levels in patients with proliferative diabetic retinopathy (PDRP) and post-vitrectomy hemophthalmia. Methods. 82 patients (82 eyes) with PDRP and post-vitrectomy hemophthalmia present 2 months (from 55 to 78 days) after performed vitrectomy were examined. Results. In patients with proliferative diabetic retinopathy (PDRP) and post-vitrectomy hemophthalmia VEGF blood level remained normal in 92.7% of cases, TNF-α blood level was normal at all times, blood level of IL-1β was within normal ranges in 93.8% of cases, and IL-1RA blood level was decreased in 74.4% of cases. Vitreous humor level was above normal ranges for VEGF - in 84% of cases, for TNF-α - in 9,9% of cases, IL-1β vitreous humor level was within reference ranges at all times, and IL-1RA vitreous humor level was decreased in 84.1% of cases. Conclusion. The gained data indicates further vascular proliferation in the eye cavity as a leading factor for hemorrhage relapses, despite the vitrectomy performed.

Los estilos APA, Harvard, Vancouver, ISO, etc.

29

Savini, Fabio, Angela Tartaglia, Ludovica Coccia, Danilo Palestini, Cristian D’Ovidio, Ugo de Grazia, Giuseppe Maria Merone, Elisa Bassotti y Marcello Locatelli. "Ethanol Determination in Post-Mortem Samples: Correlation between Blood and Vitreous Humor Concentration". Molecules 25, n.º 12 (12 de junio de 2020): 2724. http://dx.doi.org/10.3390/molecules25122724.

Texto completo

Resumen

Ethanol (ethylic alcohol) represents the most commonly used drug worldwide and is often involved in clinical and forensic toxicology. Based on several reports, excessive alcohol consumption is the main contributing factor in traffic accidents, drownings, suicides, and other crimes. For these reasons, it becomes essential to analyze the alcohol concentration during autopsy. Although blood is usually used for alcohol analysis in post-mortem cases, it could suffer alterations, putrefaction, and microbial contaminations. As an alternative to whole blood, vitreous humor has been successfully used in medico-legal studies. In this work, post-mortem specimens were analyzed for ethanol determination. The analysis of blood and vitreous humor were carried-out using gas chromatography-flame ionized detector (GC-FID) with a total run time of 6 min. The method was validated in terms of limit of detection, limit of quantification, dynamic range, sensibility, recovery, precision and trueness. A linear regression analysis indicated a coefficient of determination (R2) of 0.9981. The study confirmed no statistically differences between alcohol concentration in blood and vitreous humor, leading vitreous humor as an excellent matrix that could be used as an alternative to whole blood in toxicological analysis in cases where blood is not available.

Los estilos APA, Harvard, Vancouver, ISO, etc.

30

Rockwell, Benjamin A., C. P. Cain, G. D. Noojin, W. P. Roach, M. E. Rogers, M. W. Mayo y C. A. Toth. "Nonlinear refraction in vitreous humor". Optics Letters 18, n.º 21 (1 de noviembre de 1993): 1792. http://dx.doi.org/10.1364/ol.18.001792.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

31

Silue, Tjerignimin A., Saugandhika Mannikanti y Nathalia Peixoto. "Electrochemical Characterization of Vitreous Humor". Procedia Technology 27 (2017): 301–3. http://dx.doi.org/10.1016/j.protcy.2017.04.124.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

32

Salcedo-Villanueva, Guillermo, Veronica Kon-Jara, Mariana Harasawa, Guadalupe Cervantes-Coste, Daniel Ochoa-Contreras, Virgilio Morales-Cantón, José Luis Guerrero-Naranjo, Hugo Quiroz-Mercado y Maurice B. Landers. "Vitreous humor thermodynamics during phacoemulsification". International Ophthalmology 35, n.º 4 (7 de agosto de 2014): 557–64. http://dx.doi.org/10.1007/s10792-014-9983-z.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

33

Boulagnon, Camille, Alain Ducasse, Martine Patey, Marie-Danièle Diebold y Carl Arndt. "Cytopathology of Vitreous Humor Samples in Routine Practice". Acta Cytologica 60, n.º 1 (2016): 65–73. http://dx.doi.org/10.1159/000444576.

Texto completo

Resumen

Objective: To describe findings in vitreous fluid samples in routine cytology practice. Study Design: The pathology archives from 1988 to 2008 at our institution were searched for vitreous samples. The slides were reviewed and clinical and follow-up information was obtained. Results: One hundred and eighty-two vitreous fluid samples from 166 patients were analyzed. Most of the samples had been collected for vitreous hemorrhage (75 cases). The second reason for vitreous sample cytological evaluation was an intraocular inflammatory process (55 cases). A specific cause of inflammation was found by combining clinical, microbiological and cytopathological findings in 19 cases, i.e. infection in 7, sarcoidosis in 3, retinal necrosis in 3, lens-induced endophthalmitis in 2, uveitis associated with systemic disease in 2, retrobulbar neuritis in 1 and sympathetic ophthalmia in 1. Among the 19 samples from 16 patients collected to rule out malignancy, 8 had a confirmed intraocular malignancy. Malignant cells were observed in 5 cases (3 lymphomas, 1 melanoma and 1 carcinoma). Undiagnosed malignancies included 2 lymphomas and 1 choroidal melanoma. Other samples were collected during surgery for retinal detachment and cataracts. Conclusions: In routine practice, cytology of the vitreous fluid is performed in many and varied situations that are most often nonneoplastic. In nonneoplastic cases, cytology is a useful adjunct to vitrectomy, in spite of its limitations.

Los estilos APA, Harvard, Vancouver, ISO, etc.

34

Adenis, J. P., M. Mounier, J. L. Salomon y F. Denis. "Human Vitreous Penetration of Imipenem". European Journal of Ophthalmology 4, n.º 2 (abril de 1994): 115–17. http://dx.doi.org/10.1177/112067219400400207.

Texto completo

Resumen

The purpose of this study was to determine imipenem concentrations in vitreous humor of non-infected human eyes. Ten patients undergoing vitrectomy were infused with a single dose of either 0.5g (5 patients) or 1g (5 patients) of imipenem. Vitreous humor was withdrawn 2 or 4 hours after the end of the infusion. Results differed in relation to the dose. After 0.5g, vitreous levels were stable (approximately 0.20 mg/l), but after 1g they were significantly higher (approximately 2 mg/l). These levels were above the minimum inhibitory concentration of imipenem for 90% (MIC 90) of the main species responsible for endophthalmitis.

Los estilos APA, Harvard, Vancouver, ISO, etc.

35

Wang, Shuaishuai, Zheng Wang, Shuo Yang, Tiemei Yin, Yaoli Zhang, Yuanjun Qin, Robert N. Weinreb y Xufang Sun. "Tissue Distribution oftrans-Resveratrol and Its Metabolites after Oral Administration in Human Eyes". Journal of Ophthalmology 2017 (2017): 1–12. http://dx.doi.org/10.1155/2017/4052094.

Texto completo

Resumen

Purpose.This study was performed to measure the concentration oftrans-resveratrol and its three metabolites in human eyes.Methods.The patients who underwent pars plana vitrectomy for rhegmatogenous retinal detachment were included. The participants were orally giventrans-resveratrol-based supplement (Longevinex®). A suitable amount of conjunctiva, aqueous humor, and vitreous humor were obtained during the operation. High-performance liquid chromatography (HPLC) with mass spectrometry (LC/MS/MS) was used to detect the concentration oftrans-resveratrol and its three metabolites in the various samples.Results.The average concentration of resveratrol in the conjunctiva was 17.19 ± 15.32 nmol/g (mean ± SD). The concentration of resveratrol in the aqueous humor was close to the limit of detection, but its metabolites could be quantified. The concentrations of resveratrol metabolites in the aqueous humor can be detected. In the vitreous humor, the average concentration of resveratrol-3-O-sulfate was 62.95 ± 41.97 nmol/L. The sulfate conjugations of resveratrol were recovered in the conjunctiva, aqueous humor, and vitreous humor.Conclusions.Resveratrol and its three metabolites can be detected in the ocular tissues after oral administration. Although the concentration of parent resveratrol was low in the eyes, its metabolites could be detected and may have a role in the treatment of ocular diseases.

Los estilos APA, Harvard, Vancouver, ISO, etc.

36

James, Ross A., Paul A. Hoadley y Brett G. Sampson. "Determination of Postmortem Interval by Sampling Vitreous Humour". American Journal of Forensic Medicine and Pathology 18, n.º 2 (junio de 1997): 158–62. http://dx.doi.org/10.1097/00000433-199706000-00010.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

37

Júnior, J. Santos, C. Giane Loss, P. C. Mollo Filho, R. B. Felice Guidugli, E. Morgado Schmidt, M. Albieri Pudenzi, M. Nogueira Eberlin y N. Fenalti Höehr. "Vitreous humour: Targeted metabolomics by FT-ICR-MS". Toxicology Letters 238, n.º 2 (octubre de 2015): S236. http://dx.doi.org/10.1016/j.toxlet.2015.08.695.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

38

Neal, R. E., F. A. Bettelheim, C. Lin, K. C. Winn, D. L. Garland y J. S. Zigler. "Alterations in human vitreous humour following cataract extraction". Experimental Eye Research 80, n.º 3 (marzo de 2005): 337–47. http://dx.doi.org/10.1016/j.exer.2004.09.015.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

39

Elmali, A., S. Yabanoglu Ciftci, I. Koc, E. Nemutlu, H. Kiratli, G. Ozyigit y G. Yazici. "A Potential Novel Organ at Risk: Vitreous Humour". International Journal of Radiation Oncology*Biology*Physics 108, n.º 3 (noviembre de 2020): e567. http://dx.doi.org/10.1016/j.ijrobp.2020.07.1750.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

40

Rimpelä, Anna-Kaisa, Iiro Kiiski, Feng Deng, Heidi Kidron y Arto Urtti. "Pharmacokinetic Simulations of Intravitreal Biologicals: Aspects of Drug Delivery to the Posterior and Anterior Segments". Pharmaceutics 11, n.º 1 (30 de diciembre de 2018): 9. http://dx.doi.org/10.3390/pharmaceutics11010009.

Texto completo

Resumen

Biologicals are important ocular drugs that are be delivered using monthly and bimonthly intravitreal injections to treat retinal diseases, such as age-related macular degeneration. Long acting delivery systems are needed for prolongation of their dosing interval. Intravitreal biologicals are eliminated from the eye via the aqueous humor outflow. Thus, the anterior and posterior segments are exposed to the drug. We utilized a kinetic simulation model to estimate protein drug concentrations in the vitreous and aqueous humor after bolus injection and controlled release administration to the vitreous. The simulations predicted accurately the experimental levels of 5 biologicals in the vitreous and aqueous humor. The good match between the simulations and experimental data demonstrated almost complete anterior segment bioavailability, and major dose sparing with ocular controlled release systems. Overall, the model is a useful tool in the design of intraocular delivery of biologicals.

Los estilos APA, Harvard, Vancouver, ISO, etc.

41

Auliya, Diba G., Soni Setiadji, Zulfi Mofa Agasa, Fitrilawati, Norman Syakir y Risdiana. "Synthesis of Low Viscosity Polydimethylsiloxane Using Low Grade of Octamethylcyclotetrasiloxane". Materials Science Forum 1028 (abril de 2021): 365–70. http://dx.doi.org/10.4028/www.scientific.net/msf.1028.365.

Texto completo

Resumen

Polydimethylsiloxane (PDMS) has been widely used as a vitreous humour substitution in vitreoretinal surgery. Due to its limited availability and increasing domestic needs, the price of PDMS in Indonesia became very expensive. Previously, we reported the synthesized of PDMS from a high grade of monomer of 98% of Octamethylcyclotetrasiloxane (D4) and found that all PDMS samples produced high quality samples similar to that of commercial one. However, by considering the ease of obtaining raw materials and also the production costs, the synthesis of PDMS using monomer which easy to be found in Indonesia and low production costs is needed to be developed. Here, we reported the synthesis of PDMS using low grade of 96% of D4 in order to produce high quality of PDMS with low viscosity that can be used for vitreous humous substitution in vitreoretinal surgery. PDMS samples with low viscosity value of 0.94-1.35 Pa.s have been successfully synthesized from low grade of D4 and MM using ring-opening polymerization method. The yields of PDMS resulted in this research were in the range between 67.27% and 76.26%. From FTIR spectroscopy, it is found that all synthesized samples have structure and functional groups similar to PDMS using high grade of monomer of 98% Octamethylcyclotetrasiloxane (D4). From refractometer and surfgauge measurements, all samples have refractive index in the range of 1,4034-1,4040 and the value surface tension was 21 m.N/m.

Los estilos APA, Harvard, Vancouver, ISO, etc.

42

Clauwaert, Karine M., Jan F. Van Bocxlaer, Els A. De Letter, Serge Van Calenbergh, Willy E. Lambert y André P. De Leenheer. "Determination of the Designer Drugs 3,4-Methylenedioxymethamphetamine, 3,4-Methylenedioxyethylamphetamine, and 3,4-Methylenedioxyamphetamine with HPLC and Fluorescence Detection in Whole Blood, Serum, Vitreous Humor, and Urine". Clinical Chemistry 46, n.º 12 (1 de diciembre de 2000): 1968–77. http://dx.doi.org/10.1093/clinchem/46.12.1968.

Texto completo

Resumen

Abstract Background: The popular designer drugs 3,4-methylenedioxymethamphetamine (MDMA) and 3,4-methylenedioxyethylamphetamine (MDEA) can be determined in serum, whole blood, and urine, but also in vitreous humor. The latter matrix is interesting when dealing with decomposed bodies in a toxicological setting. Methods: After extraction, chromatographic separation was achieved on a narrow-bore C18 column by gradient elution with fluorometric detection; results were confirmed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Results: The method was linear over the range of 2–1000 μg/L for whole blood, serum, and vitreous humor, and 0.1–5 mg/L for urine. Extraction recoveries were >70%, imprecision (CV) was 2.5–19%, and analytical recoveries were 95.5–104.4%. The limit of detection (LOD) and the limit of quantification (LOQ) were 0.8 and 2 μg/L, respectively, for whole blood, serum, and vitreous humor, and 2.5 μg/L and 0.1 mg/L, respectively, for urine. Excellent correlations between the quantitative LC-fluorescence and LC-MS/MS results were obtained. We found the following concentrations in a thanatochemical distribution study in rabbits: in serum, 5.3–685 μg/L for MDMA and from the LOQ to 14.5 μg/L for 3,4-methylenedioxyamphetamine (MDA); in whole blood, 19.7–710 μg/L for MDMA and from the LOQ to 17.8 μg/L for MDA; in vitreous humor, 12.1–97.8 μg/L for MDMA and from the LOQ to 3.86 μg/L for MDA. In routine toxicological urine samples, concentrations ranged from LOQ to 14.62 mg/L for MDA, from LOQ to 157 mg/L for MDMA, and from LOQ to 32.54 mg/L for MDEA. Conclusions: The HPLC method described is sensitive, specific, and suitable for the determination of MDMA, MDEA, and MDA in whole blood, serum, vitreous humor, and urine.

Los estilos APA, Harvard, Vancouver, ISO, etc.

43

Huang, Nan, Jin-Ping Li, Xing Lu, Hua-Mei Zhu y Kai Dong. "Expression levels of ROS and Atg proteins in the vitreous in rhegmatogenous retinal detachment". International Journal of Ophthalmology 16, n.º 3 (18 de marzo de 2023): 348–53. http://dx.doi.org/10.18240/ijo.2023.03.03.

Texto completo

Resumen

AIM: To detect the concentrations of reactive oxygen species (ROS), transient receptor potential mucin-1 (TRPML1), and autophagy-related (Atg) proteins (LC3-I, LC3-II, and Beclin1) in vitreous humor of patients with simple rhegmatogenous retinal detachment (RRD). METHODS: RRD patients enrolled as the RRD group, and patients with idiopathic macular hole (IMH) and idiopathic macular epiretinal membrane (IMEM) were enrolled as control group. The levels of ROS, TRPML1, LC3-I, LC3-II, and Beclin1 in vitreous humor of patients in the RRD and control groups were detected by enzyme-linked immunosorbent assay (ELISA). RESULTS: The RRD group included 28 eyes 28 patients and had a higher concentration of ROS in vitreous humor (631.86±18.05 vs 436.34±108.22 IU/mL, P<0.05). The ROS level in patients with a wide retinal detachment (RD) extent (RD range ≥1/2) was higher than that with a narrow RD extent (RD range<1/2, P<0.05). ROS concentration was negatively correlated with RD time (r=-0.46, P=0.01). The expression levels of LC3-I and Beclin1 significantly decreased in RRD (P<0.05), but there were no correlations with the RD time, RD extent, or macular involvement. CONCLUSION: In eyes with RRD, the concentration of ROS in vitreous humor increases and the expression levels of Atg proteins decrease, reflecting possibly that autophagy is inhibited.

Los estilos APA, Harvard, Vancouver, ISO, etc.

44

Naik, Kruti, Lisa C. Du Toit, Naseer Ally y Yahya E. Choonara. "Advances in Polysaccharide- and Synthetic Polymer-Based Vitreous Substitutes". Pharmaceutics 15, n.º 2 (8 de febrero de 2023): 566. http://dx.doi.org/10.3390/pharmaceutics15020566.

Texto completo

Resumen

The vitreous humour is a gel-like structure that composes the majority of each eye. It functions to provide passage of light, be a viscoelastic dampener, and hold the retina in place. Vitreous liquefaction causes retinal detachment and retinal tears requiring pars plana vitrectomy for vitreous substitution. An ideal vitreous substitute should display similar mechanical, chemical, and rheological properties to the natural vitreous. Currently used vitreous substitutes such as silicone oil, perfluorocarbon liquids, and gases cannot be used long-term due to adverse effects such as poor retention time, cytotoxicity, and cataract formation. Long-term, experimental vitreous substitutes composed of natural, modified and synthetic polymers are currently being studied. This review discusses current long- and short-term vitreous substitutes and the disadvantages of these that have highlighted the need for an ideal vitreous substitute. The review subsequently focuses specifically on currently used polysaccharide- and synthetic polymer-based vitreous substitutes, which may be modified or functionalised, or employed as the derivative, and discusses experimental vitreous substitutes in these classes. The advantages and challenges associated with the use of polymeric substitutes are discussed. Innovative approaches to vitreous substitution, namely a novel foldable capsular vitreous body, are presented, as well as future perspectives related to the advancement of this field.

Los estilos APA, Harvard, Vancouver, ISO, etc.

45

Cox, D., R. A. Jufer Phipps, B. Levine, A. Jacobs y D. Fowler. "Distribution of Phencyclidine into Vitreous Humor". Journal of Analytical Toxicology 31, n.º 8 (1 de octubre de 2007): 537–39. http://dx.doi.org/10.1093/jat/31.8.537.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

46

Jenkins, Amanda J. y Jeffrey Oblock. "Phencyclidine and cannabinoids in vitreous humor". Legal Medicine 10, n.º 4 (julio de 2008): 201–3. http://dx.doi.org/10.1016/j.legalmed.2008.01.002.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

47

Tumram, Nilesh Keshav, Vipul Namdeorao Ambade y Anand Paikuji Dongre. "Thanatochemistry: Study of vitreous humor potassium". Alexandria Journal of Medicine 50, n.º 4 (1 de diciembre de 2014): 365–68. http://dx.doi.org/10.1016/j.ajme.2013.12.002.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

48

Elliott, Richard L., Richard Teller y Paul M. Beigelman. "RETINAL, CHOROID, AND VITREOUS HUMOR METABOLISM". Acta Ophthalmologica 43, n.º 3 (27 de mayo de 2009): 380–89. http://dx.doi.org/10.1111/j.1755-3768.1965.tb07877.x.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

49

EGGER, S. F., A. BUXBAUM, M. GEORGOPOULOS, C. SCHOLDA, V. P. VECSEI, V. HUBER-SPITZY y A. GEORGOPOULOS. "Bacterial Growth in Human Vitreous Humor". Experimental Eye Research 65, n.º 6 (diciembre de 1997): 791–95. http://dx.doi.org/10.1006/exer.1997.0385.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

50

Käsdorf, Benjamin Tillmann, Fabienna Arends y Oliver Lieleg. "Diffusion Regulation in the Vitreous Humor". Biophysical Journal 109, n.º 10 (noviembre de 2015): 2171–81. http://dx.doi.org/10.1016/j.bpj.2015.10.002.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

Artículos de revistas sobre el tema "Humour Vitrous"

Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros