Vitreous Concentrations Research Articles

Estimation of Time Since Death From Potassium Levels in Vitreous Humor in Cases of Unnatural Death: A Facility-Based Cross-Sectional Study.

Background Estimation of time since death/postmortem interval (PMI) forms a crucial component for all autopsy surgeons. With the subjectivity that is prevalent with conventional morphological and physical signs of death, newer-age modalities such as chemical analysis providebetter precision. The easy accessibility and the resistance to putrefactionmakevitreous humor the best choice for such chemical analysis. Thus, the present study's aim is to estimate the time since death in cases of unnatural death by investigating the potassium level changes in the vitreous humor. Methodology This is a facility-based cross-sectional study conducted in the mortuary under the Department of Forensic Medicine in a public tertiary healthcare teaching hospital in South India between August and September 2022. Deceased individuals fulfilling the inclusion and exclusion criteria were recruited in the study. Vitreous samples were collected from a single eye and analyzed using an autoanalyzer for potassium values. After due derivations, postmortem intervals were calculated from potassium values, then they were compared with the PMIs estimated using physical signs and those determined using official police records. Data were entered using MS Excel 20 (Microsoft Corporation, Redmond, Washington) and analyzed using the Statistical Package for the Social Sciences (SPSS) software, version 20 (IBM Corp., Armonk, NY). Results Of the 100 deceased individuals included in the study, 68%were men, and the majority (24%) belonged to the age group of 53-62 years. A linear relationship is said to exist between vitreous potassium concentration and postmortem interval. No correlation was seen between the ambient temperature and the potassium levels of the vitreous humor. PMI confirmed by the potassium levelsseconded the PMI given by the police records andphysical signs (Rigor mortis) (Spearman's rho was statistically significant at the two-tailed level or at the 0.01 level with a kappa value of 0.88). Conclusion Potassium measurements in the vitreous humor to estimate the PMI are associated with improved accuracy and precision in determining the time since death. They are not affected by external factors, makingthem a reliable marker for the same.

Comparison of the adjuvant effect of conbercept intravitreal injection at different times before vitrectomy for proliferative diabetic retinopathy.

To assess the optimal time of intravitreal conbercept (IVC) treatment prior to pars plana vitrectomy (PPV) in patients with severe proliferative diabetic retinopathy (PDR). This study was exploratory in nature. Forty-eight consecutive patients (48 eyes) with PDR were divided into four groups according to different IVC times (0.5 mg/0.05 mL) before PPV: group A (3 days), group B (7 days), group C (14 days), and group D (non-IVC). Intraoperative and postoperative effectiveness were assessed, and vitreous VEGF concentrations were detected. For intraoperative effectiveness, groups A and D had a higher incidence of intraoperative bleeding than groups B and C (P = 0.041). Furthermore, groups A-C required less surgical time than group D (P < 0.05). For postoperative effectiveness, group B had a significantly higher proportion of visual acuity that improved or remained unchanged than group D (P = 0.014), and groups A-C had lower proportions of postoperative bleeding than group D. The vitreous VEGF concentration of group B (67.04 ± 47.24 pg/mL) was significantly lower than that of group D (178.29 ± 110.50 pg/mL) (P = 0.005). IVC treatment that was administered 7 days preoperatively was associated with better effectiveness and a lower vitreous VEGF concentration than its administration at other time points.

Determination of postmortem interval and cause of death: Do the levels of biochemical parameters in vitreous humor provide an additional assistance to medico legal expert?

An upward rise has been observed in the pattern of unnatural deaths in the recent years and the same has been found during the post mortem examination. During the trial in the court of law prosecution as well as defense require the time passed death before examination and the cause of death in particular circumstances, as it is mandatory to fix the exact duration either to punish the guilty or NOT to punish the innocent. Vitreous humor is different from other body fluids as it has relative stability in its composition so as also biochemical parameters. It was further hypothesized that postmortem vitreous humor biochemistry closely mimics antemortem serum biochemistry and may be a useful aid in establishing postmortem diagnoses. Various studies have been carried out on vitreous electrolyte concentration changes to arrive at postmortem interval. Many workers found the importance of potassium in the determination of postmortem interval, whereas among all the biochemical parameters, vitreous potassium is found to be more useful to find out time since death. Postmortem biochemical analysis of vitreous humor may be helpful in the establishment of antemortem disease or metabolic disorder. The present study was carried out jointly in department of Forensic Medicine and Toxicology and department of Biochemistry of Surat Municipal Institute of Medical Education &amp; Research (SMIMER), Surat. A total of 100 subjects were taken up for this study. The samples were collected from dead bodies during postmortem examination with all aseptic precautions. A detailed performa was made with all the details of age, sex, length, weight and date and time of admission, date and time of death and manner of death such as suicide, homicide, sudden death and accidents was recorded. Cases below 15 years of age were not considered in this study. Out of 100 cases there were 24 (24%) females and 76 (76%) were males, out of these 56% were between 15-35 years, 32% were of 36-55 years, 9% were of 56-65 years, and 3% were of 66-77 years age group. According to the manner of death 50 subjects were of accident, 26 subjects were of sudden death, 21 subjects were of suicide and 3 subjects were of homicide. According to time interval between sample collection and time of death, 47 subjects were of 0-24 hours, 36 subjects were of 24-48 hours, 11 subjects were of 48-72 hours and 6 subjects were of 72-96 hours. In present study we observed that there is definitive correlation between time of death and changes in level of these biochemical parameters. This was a preliminary study in this region and can be considered as a pilot study. The levels of vitreous Potassium have been found to be significantly altered as the time progresses after death. A progressive decrease in sodium/potassium and increase in potassium/ calcium ratios was also observed.

Tenofovir Concentration Is Not Enough in Intraocular Tissues of Patients With HIV infection.

To determine tenofovir (TFV) penetration into intraocular tissues using ultra high-performance liquid chromatography/tandem mass spectrometry (UHPLC-MS/MS). Nineteen participants taking tenofovir in combination antiretroviral therapy (cART) regimen who underwent pars plana vitrectomy (PPV) surgery were enrolled in the observational retrospective study between January 2019 and August 2021. The participants were divided into mild, moderate, and severe groups according to retinal manifestations. Basic information was recorded during PPV surgery. Paired blood plasma and vitreous humor samples (n = 19) were collected for UHPLC-MS/MS. The median plasma and vitreous tenofovir concentrations were 106.00 ng/mL (interquartile range[IQR], 54.6-142.5) and 41.40 ng/mL (IQR 9.4-91.6), respectively. The median vitreous/plasma concentration ratio from the paired samples was 0.42 (IQR 0.16-0.84). The plasma and vitreous tenofovir concentrations were significantly correlated (r = 0.483, P = 0.036). The median vitreous tenofovir concentration was the lowest in the mild group (4.58 ng/mL). Six vitreous samples were below 50% inhibitory concentration (IC50) (11.5 ng/mL), and 2 of them were undetectable. Significant differences were noted in vitreous/plasma and vitreous tenofovir concentrations ( P = 0.035 and P = 0.045, respectively) among the 3 groups but not in plasma tenofovir concentration ( P = 0.577). No correlation was noted between vitreous HIV-1 RNA and vitreous tenofovir concentrations (r = 0.049, P = 0.845). Vitreous tenofovir did not reliably or consistently achieve concentrations sufficient to inhibit viral replication in intraocular tissues due to poor penetration of the blood-retinal barrier (BRB). The higher vitreous tenofovir concentrations were associated with moderate or severe disease compared with mild disease, indicating an association with the severity of BRB disruption.

Relationship between Vitreous IL-6 Levels, Gender Differences and C-Reactive Protein (CRP) in a Blood Sample of Posterior Uveitis

This study retrospectively determined the relationship between vitreous IL-6 levels and clinical and laboratory data collected from uveitis patients. We examined an unknown cause of posterior uveitis, collecting vitreous fluid to investigate vitreous IL-6 levels. The samples were analyzed in consideration of clinical and laboratory factors, such as the male/female ratio. The present study included 82 eyes from 77 patients with a mean age of 66.20 ± 15.41 years. The IL-6 concentrations of the vitreous specimens were 6255.0 ± 14,108.3 pg/mL in males and 277.6 ± 746.3 pg/mL in females, which was found to be a statistically significant difference (p = 0.048) (n = 82). There was also a statistically significant correlation between vitreous IL-6 concentrations, serum C-reactive protein (CRP) value and white blood cell counts (WBCs) (n = 82). In multivariate analysis, vitreous IL-6 levels were significantly correlated with gender and CRP in all cases (p = 0.048 and p < 0.01, respectively) and were also significantly correlated with CRP in non-infectious uveitis (p < 0.01). In infectious uveitis, there were no significant differences between IL-6 level and several variables. Vitreous IL-6 concentrations were higher in males than in females in all cases. In non-infectious uveitis, vitreous IL-6 levels were correlated with serum CRP. These results might suggest that intraocular IL-6 levels depend on gender differences in posterior uveitis, and intraocular IL-6 levels in non-infectious uveitis may reflect systemic inflammations, including increased serum CRP.

PMI estimation through metabolomics and potassium analysis on animal vitreous humour

IntroductionThe estimation of post-mortem interval (PMI) remains a major challenge in forensic science. Most of the proposed approaches lack the reliability required to meet the rigorous forensic standards.ObjectivesWe applied 1H NMR metabolomics to estimate PMI on ovine vitreous humour comparing the results with the actual scientific gold standard, namely vitreous potassium concentrations.MethodsVitreous humour samples were collected in a time frame ranging from 6 to 86 h after death. Experiments were performed by using 1H NMR metabolomics and ion capillary analysis. Data were submitted to multivariate statistical data analysis.ResultsA multivariate calibration model was built to estimate PMI based on 47 vitreous humour samples. The model was validated with an independent test set of 24 samples, obtaining a prediction error on the entire range of 6.9 h for PMI < 24 h, 7.4 h for PMI between 24 and 48 h, and 10.3 h for PMI > 48 h. Time-related modifications of the 1H NMR vitreous metabolomic profile could predict PMI better than potassium up to 48 h after death, whilst a combination of the two is better than the single approach for higher PMI estimation.ConclusionThe present study, although in a proof-of-concept animal model, shows that vitreous metabolomics can be a powerful tool to predict PMI providing a more accurate estimation compared to the widely studied approach based on vitreous potassium concentrations.

Vitreal Concentrations of Vascular Endothelial Growth Factor in Patients with Rhegmatogenous Retinal Detachment

The purpose of this study is to evaluate the concentration of vascular endothelial growth factor (VEGF) in the vitreous humor of patients with primary rhegmatogenous retinal detachment (RRD). This is a prospective case control study. Eighteen patients with primary RRD without proliferative vitreoretinopathy C (PVR C) were enrolled as cases, and twenty-two non-diabetic retinopathy patients who were candidates for complete pars plana vitrectomy due to Macular Hole or Epiretinal Membrane were included as the control group. Undiluted vitreal samples were collected during the initiation of Pars Plana Vitrectomy (PPV) prior to any infusion into the posterior cavity. Vitreous samples were also collected from 21 fresh cadaveric globes. The vitreous concentration of VEGF was measured by enzyme-linked immunosorbent assay (ELISA) technique and compared between these two groups. The vitreal concentration of VEGF was 0.643 ± 0.088 ng/mL in the RRD group. Measured concentrations of VEGF in controls were 0.043 ± 0.104 ng/mL, and in cadaveric eyes they were 0.033 ± 0.058 ng/mL. The mean VEGF concentration in the RRD group was statistically higher than in the control group (p < 0.0001) and cadaveric eyes (p < 0.0001). Our study shows that vitreal VEGF concentrations significantly increase in patients with RRD.

The Impact of Donor Preparation for Tissue Procurement on Postmortem Vitreous Isopropanol Concentration.

Volatile chemicals can be relevant in the determination of the cause and manner of death by forensic pathologists. Isopropanol is a secondary alcohol that is occasionally seen on postmortem toxicology testing. A series of 11 forensic autopsy cases was previously reported in which the presence of isopropanol in the vitreous humor was suspected to be due to postmortem contamination from the body preparation process for tissue procurement.In collaboration with a tissue procurement agency, donor vitreous humor was collected from one eye before body preparation for procurement and from the other eye postpreparation. The specimens underwent testing for volatile substances by headspace gas chromatography.Of the 50 cases, 8 (16%) showed statistically significant changes in the prepreparation and postpreparation isopropanol concentrations. Postpreparation isopropanol concentrations ranged from 5 to 104 mg/dL (median, 18 mg/dL). Seven of the 8 cases had undetectable prepreparation isopropanol, whereas the remaining case had a detectable prepreparation isopropanol.In conclusion, surface contamination of the decedent's body with chemicals used in body preparation can lead to the passive absorption into the body, resulting in the presence of isopropanol in postmortem toxicology samples. Forensic pathologists need to be aware of this when interpreting postmortem samples after tissue procurement.

Idelalisib inhibits experimental proliferative vitroretinopathy

Proliferative vitreoretinopathy (PVR) is a fibrotic eye disease that develops after rhegmatogenous retinal detachment surgery and open-globe traumatic injury. Idelalisib is a specific inhibitor of phosphoinositide 3-kinase (PI3K) δ. While PI3Kδ is primarily expressed in leukocytes, its expression is also considerably high in retinal pigment epithelial (RPE) cells, which play a crucial part in the PVR pathogenesis. Herein we show that GeoMx Digital Spatial Profiling uncovered strong expression of fibronectin in RPE cells within epiretinal membranes from patients with PVR, and that idelalisib (10 μM) inhibited Akt activation, fibronectin expression and collagen gel contraction induced by transforming growth factor (TGF)-β2 in human RPE cells. Furthermore, we discovered that idelalisib at a vitreal concentration of 10 μM, a non-toxic dose to the retina, prevented experimental PVR induced by intravitreally injected RPE cells in rabbits assessed by experienced ophthalmologists using an indirect ophthalmoscope plus a + 30 D fundus lens, electroretinography, optical coherence tomography and histological analysis. These data suggested idelalisib could be harnessed for preventing patients from PVR.Idelalisib, a specific inhibitor of phosphoinositide 3-kinase (PI3K) δ, inhibits Akt activation, fibronectin expression and collagen gel contraction induced by transforming growth factor (TGF)-β2 in human RPE cells as well as in an animal model of proliferative vitroretinopathy. These results suggest that idelalisib may be useful for preventing proliferative vitroretinopathy in humans.

The Role of Angiopoietins in Neovascular Diabetes-Related Retinal Diseases.

Diabetic retinopathy is a devastating and frequent complication of poorly controlled diabetes, whose pathogenesis is still only partially understood. Advances in basic research over the last two decades have led to the discovery of angiopoietins, proteins that strongly influence the growth and integrity of blood vessels in many vascular beds, with particular importance in the retina. Angiopoietin 1 (Ang1), produced mostly by pericytes and platelets, and angiopoietin 2 (Ang2), produced mainly by endothelial cells, bind to the same receptor (Tie2), but exert opposing effects on target cells. Ang1 maintains the stability of the mature vasculature, while Ang2 promotes vessel wall destabilization and disruption of the connections between endothelial cells and pericytes. Human retinal endothelial cells exposed to Ang2 show reduced membrane expression of the adhesion molecule VE-cadherin, and patients with proliferative diabetic retinopathy or diabetic macular edema have markedly increased vitreal concentrations of Ang2. Faricimab, a bi-specific antibody simultaneously directed against Ang2 and VEGF, has shown promising results in clinical trials among patients with diabetic retinopathy, and other agents targeting the angiopoietin system are currently in development.

Optimal timing of preoperative intravitreal anti-VEGF injection for proliferative diabetic retinopathy patients.

To analyze concentrations of vascular endothelial growth factor (VEGF) and fibrosis-related factors in vitreous fluid of proliferative diabetic retinopathy (PDR) patients pre-treated with intravitreal anti-VEGF injections (IVI) at different time periods prior to pars plana vitrectomy (PPV), and their correlation with the degree of vitreoretinal fibrosis and explore the optimal timing of preoperative IVI. The prospective case-control study from January 2019 to July 2020 included 31 eyes with PDR-related complications (PDR group) and 21 eyes with non-diabetic ocular disease (control group) requiring PPV. PDR eyes were divided into four groups based on timing of PPV: 3d after IVI (3-day group); 5d after IVI (5-day group); 7 or more days after IVI (≥7-day group); and no IVI. Vitreous fluid samples (0.5-1.0 mL) were collected prior to switching on the infusion before routine 23-G PPV. Concentrations of VEGF, basic fibroblast growth factor (bFGF), periostin (PN), interleukin (IL)-6, IL-8, and tumor necrosis factor (TNF)-α were measured by immunoassay, and concentration differences for each cytokine were compared among the groups. The degree of vitreoretinal fibrosis was graded intraoperatively, and the correlation between the changes in cytokine levels and the severity of vitreoretinal fibrosis was analyzed by univariate ordinal logistic regression analysis. PDR eyes without IVI had significantly higher VEGF, bFGF, PN, and IL-6 concentrations than non-diabetic eyes (all P<0.05), and had a significantly higher concentration of VEGF (P<0.05) and a significantly lower concentration of IL-8 (P<0.05) than PDR eyes with IVI. Statistically significant differences were also observed for concentrations of VEGF, bFGF, PN, IL-6, and IL-8 among 3-day, 5-day, and ≥7-day groups (all P<0.05); meanwhile there was no significant difference in TNF-α among groups (P=0.226). The 5-day group had the lowest concentration of VEGF and the ≥7-day group had the highest concentration of bFGF and PN. The degree of vitreoretinal fibrosis was significantly higher in the ≥7-day group compared to the 3-day (P=0.015) and 5-day group (P=0.039), and vitreoretinal fibrosis correlated significantly with concentrations of bFGF, PN, IL-6, and IL-8 (all P<0.05). Univariate ordinal logistic regression analysis showed that bFGF was an independent risk factor for the severity of vitreoretinal fibrosis in PDR patients pre-treated with IVI. The vitreous concentrations of VEGF, bFGF, PN, IL-6, and IL-8 change after pretreatment with IVI before PPV in PDR patients. The degree of vitreoretinal fibrosis is higher in patients with a longer time between IVI treatment and PPV, which may be related to the angio-fibrosis switch. The results suggest that PPV should be performed 5d after IVI administration in PDR patients.

IPMICALC: an Integrated Post-mortem Interval Calculator.

Correctly estimating the post-mortem interval (PMI) is essential in forensic practice. In recent decades, the measurement of vitreous humor analyte concentrations - especially of hypoxanthine and potassium - and their correlation with the PMI have returned good results. However, calculating the PMI from the data collected can be quite complex. The present paper describes a web resource ( http://modestya.usc.es:3838/Forensic/ ) that simplifies the procedure. The PMI is determined (with its 95% confidence interval) in a rapid, easy, and reliable manner based on the use of mathematical models, the biochemistry of the vitreous humor, and physical variables such as the ambient temperature, the rectal temperature, and bodyweight. The application is entirely free to use.

Effect of pan-retinal laser photocoagulation on intravitreal vascular endothelial growth factor concentration in proliferative diabetic retinopathy.

Objective: This study aimed to determine the intravitreal concentration of VEGF in eyes with PDR and to evaluate the effects of previous PRP on its level. Methods: It was a cross-sectional study performed at the Clinical Centre University. It included 90 eyes surgically treated with PPV, divided into three groups, group A - patients with PDR with previous PRP, group B - patients with PDR without previous PRP, and group C - PPV performed due to the indication unrelated to diabetes. A vitreous sample was obtained during PPV, and the VEGF concentration was determined using an Enzyme-linked immunosorbent assay test (ELISA). Shapiro-Wilk, nonparametric tests Kruskal-Wallis, Mann-Whithney U test, ANOVA and Spearman's correlation test were used. Results: The highest vitreous VEGF concentration was in group B - 972.96 (743.33-1149.13) and was higher than in group A - 69.22 (37.33-225.15) and in group C - 19.93 (1.15-32.17) (p<0.001). There was a positive correlation between VEGF vitreous concentration and glucose level in group A patients (Rho=0.410; p=0.027). Conclusion: As a treatment before PPV surgery, PRP showed to be effective in the reduction of VEGF levels, which also highlighted a decrease in complications during and postoperatively. Abbreviations: DRS = Diabetic Retinopathy Study, PDR = proliferative diabetic retinopathy, VEGF = vascular endothelial growth factor, PRP = pan-retinal photocoagulation, PPV = pars plana vitrectomy, HbA1c = glycosylated hemoglobin, ETDRS = Early treatment diabetic retinopathy study, ESR = erythrocyte sedimentation rate, BCVA = best corrected visual acuity, OCT = optical coherent tomography, ILM = internal limiting membrane, PHACO = phacoemulsification, IOL = intraocular lens, ELISA = Enzyme-linked immunosorbent assay test, AUC = area under the curve, DME = diabetic macular oedema, TDR = tractional retinal detachment, VMT = vitreomacular traction.

Plasma and vitreous selenium concentrations in patients with type 2 diabetes and diabetic retinopathy.

Background:This work aimed to determine and compare plasma and vitreous selenium (Se) concentrations in patients with type 2 diabetes and diabetic retinopathy (DR).Methods:A total of 60 type-2-diabetes patients including 20 without DR, 20 with non-proliferative DR (NPDR), and 20 with proliferative diabetic retinopathy (PDR), were involved in this study. Blood plasma samples were collected from above 60 patients and 20 normal controls (without diabetes). Twenty control vitreous samples were obtained from the eyes presenting a macular hole and epimacular membrane. Vitreous samples were also collected from PDR patients receiving one-week intravitreal anti-VEGF therapy or not. Plasma and vitreous Se concentrations were determined by inductively coupled plasma mass spectrometry.Results:Plasma Se concentrations in PDR patients (163.74 ± 32.68 μg/L) were significantly higher than those in normal control patients (121.59 ± 28.33 μg/L), NPDR patients (130.34 ± 29.11 μg/L), and the patients without DR (81.23 ± 20.59 μg/L) (all P < .001). Similarly, Se concentrations in vitreous samples of PDR patients (56.30 ± 12.03 μg/L) were consistently higher than those in control vitreous samples (26.26 ± 6.53 μg/L). In addition, vitreous Se concentrations in PDR patients decreased to 47.76 ± 9.72 μg/L after intravitreal injection of the anti-VEGF drug ranibizumab for one week, which was significantly lower than those before injection (P = .02). Plasma VEGF levels of diabetic patients were lower than those of the normal controls (P < .001). On the contrary, the vitreous VEGF level in the PDR group (913.61 ± 193.32 pg/mL) was significantly higher than that of the normal control group (101.23 ± 21.33 pg/mL) (P < .001).Conclusion:The elevation of Se concentrations may be an important risk factor in plasma and vitreous with diabetic retinopathy among type-2-diabetes patients. The elevated VEGF may be also closely related to the intraocular Se concentration in PDR patients.

Topical ophthalmic administration: Can a drug instilled onto the ocular surface exert an effect at the back of the eye?

Topical ophthalmic instillation is an appealing strategy to deliver drugs to the back of the eye to treat retinal diseases such as neovascular age-related macular degeneration, diabetic retinopathy, retinal vein occlusion, and glaucomatous optic neuropathy. It has several advantages such as being non-invasive and user-friendly, e.g., allowing self-administration. However, the main obstacle has been how to achieve therapeutic drug concentrations in the retina due to the eye’s protective mechanisms, flows, and barriers. Less than 4% of the instilled drug dose enters the anterior chamber, and much less is expected to reach the posterior segment. It is crucial to understand a drug’s topical pharmacokinetics in humans and how one can extrapolate data from rabbits to humans. In this review, the available data on the retina and vitreous drug concentrations from pharmacokinetics studies conducted in human patients and rabbits have been compiled, together with the critical physiological factors to be considered for this route of administration. Improvements in the design of preclinical studies are suggested to increase their translatability to the treatment of human patients. Finally, the current status of clinical trials with topical ophthalmic formulations intended to treat the back of the eye is depicted. At present, no topical ophthalmic formulations to treat neovascular age-related macular degeneration or other retinal neurodegenerative illnesses have reached the market.

Utility of a Handheld Blood Ketone Meter as a Postmortem Indicator of Diabetic Ketoacidosis.

When investigating a death potentially due to diabetic ketoacidosis (DKA), it is challenging to assess the glucose level in the blood, but β-hydroxybutyrate, the most prevalent ketone body in the blood, is relatively stable after death. The aim of this project is to prove that a commercially available ketone meter can be used on postmortem blood samples to aid the diagnosis of DKA in a novel setting (during coroner/medical examiner examination). Samples with acetone detected via gas chromatography were chosen retrospectively to determine whether the meter could detect ketones in postmortem blood (proof-of-concept). In all of the thawed samples, the meter detected an elevated ketone level. Samples were then obtained in a prospective manner to include those with a possible cause of death from DKA along with controls. We correctly identified 16 cases in which death was due to DKA with use of the ketone manner. The ketone levels ranged from 2.6 to 5.4 mmol/L in those cases. The diagnosis was confirmed with a greatly elevated vitreous glucose concentration or glycated hemoglobin concentration. Detecting the presence of ketones while in the autopsy suite allowed for more accurate preliminary diagnoses and utilization of resources.

Systemic prime exacerbates the ocular immune response to heat-killed Mycobacterium tuberculosis

Post-infectious uveitis describes the condition of chronic immune mediated ocular inflammation associated with pathogens such as Mycobacterium tuberculosis (Mtb). Mtb associated post-infectious uveitis can be modeled in mice by intravitreal injection of heat-killed Mtb (HKMtb). To better understand how prior systemic exposure to the pathogen alters the local immune response to Mtb, we used flow cytometry and multiplex ELISAs to compare ocular responses to intravitreal HKMtb in the presence or absence of a systemic “prime” of HKMtb. Priming resulted in exacerbation of local inflammation with significantly increased clinical and histologic inflammation scores and increased vitreous cytokines concentrations one day after intravitreal injection of HKMtb. Seven days after injection, uveitis in unprimed animals had largely resolved. In contrast in primed animals, clinical signs of chronic inflammation were associated with a significant increase in the number of ocular T cells, NK cells, and Ly6Chi macrophages and increasing vitreous concentrations of IL-17, VEGF, MIG(CXCL9), IP-10(CXCL10), IL-12p40 and MIP-1α(CCL3). In mice lacking mature T and B cells (RAG2 deficient), the impact of priming on the ocular immune response was ameliorated with significantly lower vitreous cytokine concentrations and spontaneous resolution of uveitis. Altogether these results suggest that the ocular response to Mtb is exacerbated by prior systemic Mtb infection and chronic post-infectious uveitis is mediated by local production of cytokines and chemokines that amplify Th17 and Th1 responses. This mouse model of chronic Mtb associated uveitis will help elucidate mechanisms of disease in patients with post-infectious uveitis.

Elevated Retinol Binding Protein 3 Concentrations Are Associated With Decreased Vitreous Inflammatory Cytokines, VEGF, and Progression of Diabetic Retinopathy.

To correlate inflammatory cytokines and vascular endothelial growth factor (VEGF) in vitreous and plasma with vitreous retinol binding protein 3 (RBP3), diabetic retinopathy (DR) severity, and DR worsening in a population with type 1 and type 2 diabetes. RBP3, VEGF, and inflammatory cytokines were measured in plasma and vitreous samples (n = 205) from subjects of the Joslin Medalist Study and Beetham Eye Institute. Higher vitreous RBP3 concentrations were associated with less severe DR (P < 0.0001) and a reduced risk of developing proliferative DR (PDR) (P < 0.0001). Higher RBP3 correlated with increased photoreceptor segment thickness and lower vitreous interleukin-12 (IL-12), tumor necrosis factor-α (TNF-α), and TNF-β (P < 0.05). PDR was associated with lower vitreous interferon-γ and IL-10 and higher VEGF, IL-6, and IL-15 (P < 0.05), but was not associated with their plasma concentrations. Higher vitreous RBP3 concentrations are associated with less severe DR and slower rates of progression to PDR, supporting its potential as a biomarker and therapeutic agent for preventing DR worsening, possibly by lowering retinal VEGF and inflammatory cytokines.

Quantitative pharmacokinetic analyses of anterior and posterior elimination routes of intravitreal anti-VEGF macromolecules using published human and rabbit data

The purpose of this study was to evaluate the contribution of the anterior elimination route for four anti-vascular endothelial growth factor (anti-VEGF) macromolecules (aflibercept, bevacizumab, pegaptanib and ranibizumab) after intravitreal injection using published human and rabbit data and three previously described pharmacokinetic (PK) modeling methods.A PubMed search was used to identify published studies with concentration-time data. The data were utilized only if the intravitreally injected drugs were used as plain solutions and several criteria for a well-performed PK study were fulfilled. The three methods to analyze rabbit data were (1) the equation for vitreal elimination half-life based molecular size assuming anterior elimination, (2) Maurice equation and plot for the ratio of aqueous humor (AH) to vitreal concentration assuming anterior elimination, and (3) the equation for amount of macromolecule eliminated anteriorly based on the area under the curve in AH. The first and third methods were used for human data. In the second and third methods, AH flow rate is a key model parameter, and it was varied between 2 and 3 μl/min.The methods were applied to data from 9 rabbit studies (1 for aflibercept, 5 for bevacizumab, and 3 for ranibizumab) and 5 human studies (1 for aflibercept, 3 for bevacizumab, and 1 for ranibizumab). Experimental half-lives of anti-VEGF macromolecules in both vitreous and aqueous humor were close to those calculated with the equations for vitreal elimination half-life in humans and rabbits. Rabbit data analyzed with Maurice plot indicated that the contribution of anterior elimination was usually at least 75%. In most human and rabbit studies, the calculated percentage of anterior elimination was at least 51%. Variability between studies was extensive for bevacizumab and ranibizumab.The results suggest that the anterior elimination route dominates after intravitreal injection of anti-VEGF macromolecules. However, the clinical data are sparse and variability is extensive, the latter emphasizing the need of proper experimental design.

42-OR: Association of Vitreous Retinol Binding Protein 3 with Inflammatory Cytokines and Progression of Diabetic Retinopathy in Type 1 and Type 2 Diabetes

Although inflammatory cytokines and vascular endothelial growth factor (VEGF) have been proposed to underlie the progression of diabetic retinopathy (DR) , there remains an important need to identify biomarkers for early stages of DR. Findings from the Joslin Medalist Study, composed of individuals who have had insulin-dependent diabetes for 50 years or longer, showed that Retinol Binding Protein 3 (RBP3) was significantly higher both in retina and vitreous samples with no to mild DR compared to those with proliferative DR (PDR) . In this study, we examined vitreous and plasma samples from 2people with type 1 and type 2 diabetes from the Joslin Beetham Eye Institute and Medalist Study to evaluate the relationship between vitreous RBP3, inflammatory cytokines, and DR severity and progression. PDR was associated with lower levels of IL- (P=0.007) , IFN-γ (P=0.001) , and higher levels of IL-15 (P=0.01) and IL-6 (P=0.02) in vitreous. Vitreous VEGF was positively associated with increasing DR severity in surgical samples (P&amp;lt;0.05) . Plasma VEGF was not associated with vitreous VEGF concentration. No significant relationships were found between inflammatory markers in the vitreous and plasma from the same individual. Increased vitreous RBP3 concentration was associated with less severe DR in all eyes (P&amp;lt;0.0001) , post-mortem (P&amp;lt;0.0001) and surgical samples from type 1 and type 2 diabetic patients (P=0.03) with diabetes duration of &amp;lt;50 years (mean±SD 27±13 years) . Higher vitreous RBP3 concentration was associated with lower risk of PDR onset (P&amp;lt;0.0001) . Lower vitreous TNF-α, TNF-β, and VEGF were associated with increased vitreous RBP3 concentration (P&amp;lt;0.05, all) . These findings suggest that inflammatory cytokines and risk of DR worsening may be decreased by RBP3, supporting its potential use as biomarker for severity and progression of DR. Disclosure W.Fickweiler: None. J.D.Cavallerano: None. L.P.Aiello: Consultant; KalVista Pharmaceuticals, Inc., Novo Nordisk, Stock/Shareholder; KalVista Pharmaceuticals, Inc. J.Sun: Consultant; American Diabetes Association, American Medical Association, Research Support; Adaptive Sensory Technology, Boehringer Ingelheim International GmbH, Genentech, Inc., Jaeb Center for Health Research, Janssen Pharmaceuticals, Inc., Novartis Pharmaceuticals Corporation, Novo Nordisk, Optovue, Incorporated, Physical Sciences, Inc, Roche Pharmaceuticals. G.L.King: Advisory Panel; Medtronic, Research Support; Janssen Pharmaceuticals, Inc. H.Park: None. K.Park: None. M.G.Mitzner: None. D.B.Robinson: None. T.Chokshi: None. T.Boumenna: None. J.Gauthier: None. I.Wu: None. Funding American Diabetes Association (7-21-PDF-022) ; National Eye Institute (R01EYE26080-01) , the National Institute of Diabetes and Digestive and Kidney Diseases and National Institutes of Health (DP3-DK-094333-01) ; JDRF (17-2013-310) ; the Dianne Nunnally Hoppes Fund; the Beatson Pledge Fund