Changes of 1, 5-AG in Vitreous Humor of Rabbit Cadavers with Hyperglycemic Metabolism / 法医学杂志

OBJECTIVES@#To investigate the concentration and change characteristics of 1, 5-anhydroglucitol (1, 5-AG) in the vitreous humor of rabbit cadavers with hyperglycemic metabolism, and to explore the value of 1, 5-AG in forensic pathology identification of death caused by hyperglycemic metabolism disorders.@*METHODS@#A diabetic hyperglycemic rabbit model was established by using alloxan. Eighteen rabbits with fasting glucose concentration ≥13.80 mmol/L (experimental group) and 18 healthy rabbits with fasting glucose concentration ≤6.10 mmol/L (control group) were selected. After death from air embolism. The blood samples were collected immediately, and vitreous humor samples were collected at 0 h, 12 h, 24 h and 36 h after death. The concentration of 1, 5-AG in the blood and vitreous humor of rabbits was determined.@*RESULTS@#The blood glucose concentration in the experimental group was (25.10±3.14) mmol/L. At the time of death, there was no significant difference in the concentration of 1, 5-AG in the blood [(0.94±0.20) μg/mL] and in the vitreous humor (0.99±0.05 μg/mL, P>0.05). The concentration of 1, 5-AG in the vitreous humor of the experimental group was lower than that of the corresponding control group at all time points (P<0.05), and there was no significant difference betwwen 1, 5-AG concentration in vitreous humor between earch time point in the experimental group and the control group (P>0.05). Correlation analysis showed that the concentration of 1,5-AG in blood was negatively correlated with blood glucose in both control group and experimental group (control group: r=-0.79, P<0.05; experimental group: r=-0.97, P<0.05).@*CONCLUSIONS@#Vitreous humor can replace blood as an effective test sample for 1,5-AG detection. The concentration of 1, 5-AG in rabbit vitreous humor remains stable within 36 hours after death and is not affected by the change of postmortem interval. If the concentration of 1, 5-AG decreases significantly, it indicates the existence of hyperglycemia in rabbits before death.

Inferring Postmortem Submersion Interval in Rats Found in Water Based on Vitreous Humor Metabolites / 法医学杂志

OBJECTIVES@#The metabolomics technique of LC-MS/MS combined with data analysis was used to detect changes and differences in metabolic profiles in the vitreous humor of early rat carcasses found in water, and to explore the feasibility of its use for early postmortem submersion interval (PMSI) estimation and the cause of death determination.@*METHODS@#The experimental model was established in natural lake water with 100 SD rats were randomly divided into a drowning group (n=50) and a postmortem (CO2 suffocation) immediately submersion group (n=50). Vitreous humor was extracted from 10 rats in each group at 0, 6, 12, 18 and 24 h postmortem for metabolomics analyses, of which 8 were used as the training set to build the model, and 2 were used as test set. PCA and PLS multivariate statistical analysis were performed to explore the differences in metabolic profiles among PMSI and causes of death in the training set samples. Then random forest (RF) algorithm was used to screen several biomarkers to establish a model.@*RESULTS@#PCA and PLS analysis showed that the metabolic profiles had time regularity, but no differences were found among different causes of death. Thirteen small molecule biomarkers with good temporal correlation were selected by RF algorithm. A simple PMSI estimation model was constructed based on this indicator set, and the data of the test samples showed the mean absolute error (MAE) of the model was 0.847 h.@*CONCLUSIONS@#The 13 metabolic markers screened in the vitreous humor of rat corpses in water had good correlations with the early PMSI. The simplified PMSI estimation model constructed by RF can be used to estimate the PMSI. Additionally, the metabolic profiles of vitreous humor cannot be used for early identification of cause of death in water carcasses.

Vitreous pharmacokinetics and electroretinographic findings after intravitreal injection of acyclovir in rabbits

OBJECTIVES: Acute retinal necrosis is a rapidly progressive and devastating viral retinitis caused by the herpesvirus family. Systemic acyclovir is the treatment of choice; however, the progression of retinal lesions ceases approximately 2 days after treatment initiation. An intravitreal injection of acyclovir may be used an adjuvant therapy during the first 2 days of treatment when systemically administered acyclovir has not reached therapeutic levels in the retina. The aims of this study were to determine the pharmacokinetic profile of acyclovir in the rabbit vitreous after intravitreal injection and the functional effects of acyclovir in the rabbit retina. METHODS: Acyclovir (Acyclovir; Bedford Laboratories, Bedford, OH, USA) 1 mg in 0.1 mL was injected into the right eye vitreous of 32 New Zealand white rabbits, and 0.1 mL sterile saline solution was injected into the left eye as a control. The animals were sacrificed after 2, 9, 14, or 28 days. The eyes were enucleated, and the vitreous was removed. The half-life of acyclovir was determined using high-performance liquid chromatography. Electroretinograms were recorded on days 2, 9, 14, and 28 in the eight animals that were sacrificed 28 days after injection according to a modified protocol of the International Society for Clinical Electrophysiology of Vision. RESULTS: Acyclovir rapidly decayed in the vitreous within the first two days after treatment and remained at low levels from day 9 onward. The eyes that were injected with acyclovir did not present any electroretinographic changes compared with the control eyes. CONCLUSIONS: The vitreous half-life of acyclovir is short, and the electrophysiological findings suggest that the intravitreal delivery of 1 mg acyclovir is safe and well tolerated by the rabbit retina.

Latest progress in postmortem interval estimation / 法医学杂志

Accurate estimation of the postmortem interval (PMI) has been one of the most important and complicated issues in the forensic practice. In order to provide novel perspectives for the future research concerning PMI, the advantages and disadvantages of related traditional methods, postmortem degradation of nucleic acid and tissue, the componential change of vitreous humor and histological biochemistry since 2002 have been introduced and compared in this review.

A Potential Role of Crystallin in the Vitreous Bodies of Rats after Ischemia-reperfusion Injury

PURPOSE: Ischemia-reperfusion injury (I/R injury) is known not only to induce hypoxic and oxidative stress, but also to cause retinal degeneration in rats. Crystallins, known to inhibit the formation of reactive oxygen species, reduce apoptotic cell death. Our goal was to clarify not only the role of I/R injury-mediated crystallins, but also to evaluate the correlation of these compounds to anti-inflammation in the vitreous body. METHODS: Twenty-four Sprague-Dawley rats were used in this study. We induced I/R injury by clamping the optic nerve for 30 minutes and then releasing it. The vitreous bodies were obtained from the experimental and control subjects 24, 48, and 72 hours after I/R injury. Two-dimensional electrophoresis was performed, and the targeted spots were further investigated using matrix-assisted laser desorption-ionization time-of-flight mass spectrometry, spectrophotometry, Western blotting, and histological examination. RESULTS: After I/R injury, 23 spots were identified as crystallins. The betaB2 crystallins were transcriptionally and post-translationally regulated, whereas the alphaB crystallins were controlled by post-translational modifications in the vitreous bodies of the rats. The total amounts of alphaA and beta crystallins (including isotypes of beta crystalline) had increased 48 hours after injury. The phosphorylation of alphaB crystallin (at serine residues 19, 45, and 59) was significantly increased 48 hours later, whereas phosphorylation of ERK1/2 showed the greatest decrease. CONCLUSIONS: During hypoxic and oxidation stress, our results suggest that phosphorylated alphaB crystalline inhibits RAS, resulting in the inactivation of ERK1/2. The phosphorylation of alphaB crystallin may be associated with the inflammatory suppression in the vitreous body via the I/R injury model system.

Intravitreal injection of methotrexate in an experimental rabbit model: Determination of pharmacokinetics.

Purpose: To investigate the pharmacokinetics of intravitreally administered methotrexate. Materials and Methods: Twenty-one New Zealand white rabbits were used in the study. The pharmacokinetics of intravitreally injected 800 μg/0.1 ml of methotrexate was investigated. Intravitreal concentration of the drug was measured at seven different times, in six eyes at each occasion, on a total of 42 eyes of 21 rabbits from a period of 30 minutes to 72 hours. Results: The volume of distribution was calculated as 1.33 ml following intravitreal injection of 800 μg methotrexate. Vitreous concentrations of the drug were found to be decreasing related to the specific mathematical equation; drug concentration= 1426.73 e-0.1182(time) and remained over effective dose by 81 hours with a half life of 5.9 hours. Conclusions: These findings evidenced those vitreous levels of methotrexate at various time intervals after 800 μg intravitreal injections which formulated a mathematical equation for calculation of vitreous level of the drug at each hour.

Successful management of presumed Candida endogenous endophthalmitis with oral voriconazole.

Endogenous fungal endophthalmitis is most commonly caused by Candida species and usually occurs in patients with chronic diseases such as diabetes mellitus and renal insufficiency. Voriconazole, a broad-spectrum triazole antifungal agent, attains therapeutically significant concentrations in the vitreous cavity after systemic administration. We report, the successful management of presumed endogenous Candida endophthalmitis in a patient with multiple diseases and unstable systemic status with oral voriconazole. Though fungal endophthalmitis has been successfully treated with a combination of intravenous and intravitreal voriconazole, to the best of our knowledge this is the first report in ophthalmic literature (Medline Search) on the treatment of fungal endophthalmitis with only the oral route of administration of voriconazole.

Trace elements iron, copper and zinc in vitreous of patients with various vitreoretinal diseases.

PURPOSE: To measure the concentrations of iron, copper and zinc in human vitreous and to interpret their levels with various vitreoretinal diseases like proliferative diabetic retinopathy, retinal detachment, intraocular foreign body, Eales' disease and macular hole. METHODS: Undiluted vitreous fluid collected during pars plana vitrectomy was used to measure trace elements using an atomic absorption spectrophotometer. RESULTS: The level of vitreous iron increased threefold in Eales' disease (1.85 +/- 0.36 pg/ml), 2.5-fold in proliferative diabetic retinopathy (1.534 +/- 0.17 pg/ml) and 2.3-fold in eyes with intraocular foreign body (1.341 +/- 0.25 pg/ml) when compared with macular hole (0.588 +/- 0.16 pg/ml). This was statistically significant (P < 0.05). Zinc was found to be low in Eales' disease (0.57 +/- 0.22 pg/ ml) when compared with other groups, though the difference was not statistically significant. CONCLUSION: The increased level of iron with decreased zinc content in Eales' disease confirms the earlier reported oxidative stress mechanism for the disease. In proliferative diabetic retinopathy and intraocular foreign body the level of iron increases. This is undesirable as iron can augment glycoxidation, which can lead to increased susceptibility to oxidative damage, in turn causing vitreous liquefaction, posterior vitreous detachment and ultimately retinal detachment and vision loss.

Seguimiento ecográfico del vítreo en pacientes pre y postLasik / Ultrasound monitoring of vitreous in pre and postLasik patients

Objetivo: reportar los cambios ecográficos observados en el vítreo en pacientes postLasik. Metodología: estudio prospectivo, observacional y descriptivo. Método: Se realizó ecografía modo A y B prequirúrgica y controles postoperatorios al primer y tercer mes en 16 pacientes sometidos a cirugía refractiva en la Fundación Oftalmológica Nacional entre junio 2002 y marzo 2003. Resultados: 16 pacientes, 67 por ciento mujeres y 33 por ciento hombres, con una edad promedio de 31.6 años y rango entre 22 y 40 años. Promedio de 31 años, en 29 ojos, 16 derechos y 13 izquierdos, para un total de 87 ecografías. Los defectos refractivos se encontraban en un rango entre -10.50 y +3.50 de equivalente esférico, 24 ojos miopes y 5 hipermétropes; los cambios correspondían a DVP (desprendimiento de vítreo posterior) y presencia de opacidades; al inicio del estudio, 18 ojos (62 por ciento) presentaban DVP y todos los 29 ojos presentaban opacidades; al final de los controles ecográficos se evidenciaron cambios en 22 ojos (81 por ciento) del total, dentro de los cuales aumentaron las opacidades vítreas en 14 ojos (48.27 por ciento), mientras que permanecieron sin modificación 15 ojos (51.7 por ciento). La presencia de DVP de novo se evidenció en 10 ojos (30 por ciento), un aumento del DVP en 8 ojos (27.5 por ciento) y en un caso (3.4 por ciento) se observó la presencia de un área de tracción en lainterfase vitreo-retiniana, que corresponde a un paciente hipermétrope, el cual fue evaluado al observarse 2 agujeros retinianos operculados en el tercer control ecográfico. Conclusiones: demostramos que realmente se evidencian cambios a nivel vítreo postLasik, dentro de los cuales el desprendimiento del vítreo posterior es el hallazgo más significativo y podría estar implicado en la génesis de desgarros en retina, pero su incidencia es aún equiparable a la de la población general, lo que hace que la cirugía refractiva permanezca como un procedimiento seguro. Sin embargo, sugerimos que los...

Transthyretin (prealbumin) in eye structures and variation of vitreous-transthyretin in diseases.

PURPOSE: To evaluate the presence of transthyretin (TTR, prealbumin) a protein which binds retinol to retinol-binding protein in various ocular tissues and to study its quantitative changes in the vitreous humor in various diseases. METHOD: Estimation of TTR was done by electrophoresis of 10 mg protein in each sample of tears, aqueous humor, vitreous, retina, and lens by an Imaging Densitometer using prealbumin as the standard. RESULTS: TTR was present in all the eye structures except the lens and tear. The retina and the vitreous had relatively higher amounts of TTR compared with aqueous. The identity of TTR was confirmed by immuno-electrophoresis using anti-human TTR. Two bands in SDS electrophoresis revealed that this protein is a heterodimer. There was a significant decrease in vitreous TTR in diabetes with hypertension and increase in one case each of diabetes with hypertension associated with leukaemia or carcinoma with hepato-splenomegaly. CONCLUSION: Vitreous TTR is probably from retina and retinal pigment epithelium. The level of vitreous TTR is likely to have diagnostic significance in some retinal diseases.

Cellular components of proliferative vitreoretinal membranes

To understand the pathogenesis of proliferative vitreoretinal membrane formation which occurs in proliferative vitreoretinopathy (PVR) and proliferative diabetic retinopathy (PDR), etc., accurate identification of the cellular components of the membrane is needed. This study was performed to identify cellular components of the membranes by means of immunohistochemical technique. 11 proliferative vitreoretinal membranes which were surgically obtained from 7 eyes with PVR and 4 eyes with PDR were stained with monoclonal antibodies against cytokeratin, glial fibrillary acidic protein (GFAP), or vimentin using immunoperoxidase technique (ABC method). In the PVR membranes, mean cell positivities for cytokeratin, GFAP and vimentin were 48%, 1% and 92%, respectively and in the PDR membranes, 0%, 5% and 93%, respectively. The above results suggest that retinal pigment epithelial cells and fibroblasts are major cellular components of PVR membranes, and that mesenchymal cells are major cellular components and glial cells are minor cellular components of PDR membranes.

Pharmacokinetics of intravitreally injected liposome-encapsulated tobramycin in normal rabbits

Bacterial endophthalmitis, which is a devastating complication of intraocular surgery or eye trauma, has a poor prognosis. Intravitreal injection of antimicrobial agents has become a part of the standard treatment of endophthalmitis. The authors investigate the pharmacokinetics of intravitreal liposome-encapsulated tobramycin as a possible method of prolonging the duration of therapeutic concentrations. Tobramycin was encapsulated into liposomes of phosphatidylcholine, phosphatidic acid, and alpha-tocopherol by the reverse phase evaporation method. The final liposomal suspension contained tobramycin, 7.0 mg/ml, 60.5% encapsulated. One eye received an intravitreal injection of either liposome-encapsulated tobramycin (LET), tobramycin phosphated-buffered saline (TS) or a mixture of tobramycin and liposome-encapsulated saline (TEL), and the results were as follows: 1. Concentrations of free tobramycin were significantly lower with LET than with TS or TEL at 1 hour after intravitreal injection. 2. Concentrations of free and total tobramycin were significantly higher with LET than with TS or TEL at 5 and 8 days after intravitreal injection. Concentrations of free tobramycin with TS were lower than the minimal inhibitory concentration(MIC) of tobramycin for Pseudomonas aeruginosa at 8 days after intravitreal injection, while those with LET were higher than the MIC of tobramycin for Pseudomonas aeruginosa 18 days after injection.