Intraocular pressure and aqueous humor flow during a euglycemic-hyperinsulinemic clamp in patients with type 1 diabetes and microvascular complications

<p>Abstract</p> <p>Background</p> <p>Microvascular complications, including retinopathy and nephropathy are seen with type 1 diabetes. It is unknown whether functional changes in aqueous humor flow or intraocular pressure (IOP) develop in parallel with these complications. This study was designed to test the hypothesis that clinical markers of microvascular complications coexist with the alteration in aqueous humor flow and IOP.</p> <p>Methods</p> <p>Ten patients with type 1 diabetes and ten healthy age- and weight-matched controls were studied. Aqueous flow was measured by fluorophotometry during a hyperinsulinemic-euglycemic clamp (insulin 2 mU/kg/min). Intraocular pressure was measured by tonometry at -10, 90 and 240 minutes from the start of the clamp, and outflow facility was measured by tonography at 240 minutes.</p> <p>Results</p> <p>During conditions of identical glucose and insulin concentrations, mean aqueous flow was lower by 0.58 μl/min in the diabetes group compared to controls (2.58 ± 0.65 versus 3.16 ± 0.66 μl/min, respectively, mean ± SD, p = 0.07) but statistical significance was not reached. Before the clamp, IOP was higher in the diabetes group (22.6 ± 3.0 mm Hg) than in the control group (19.3 ± 1.8 mm Hg, p = 0.01) but at 90 minutes into the clamp, and for the remainder of the study, IOP was reduced in the diabetes group to the level of the control group. Ocular pulse amplitude and outflow facility were not different between groups. Systolic blood pressure was significantly higher in the diabetes group, but diastolic and mean arterial pressures were not different.</p> <p>Conclusions</p> <p>We conclude that compared to healthy participants, patients with type 1 diabetes having microalbuminuria and retinopathy have higher IOPs that are normalized by hyperinsulinemia. During the clamp, a reduction in aqueous flow was not statistically significant.</p

Is post-trabeculectomy hypotony a risk factor for subsequent failure? A case control study

BACKGROUND: Ocular hypotony results in an increased break down of the blood-aqueous barrier and an increase in inflammatory mediator release. We postulate that this release may lead to an increased risk of trabeculectomy failure through increased bleb scarring. This study was designed to try to address the question if hypotony within one month of trabeculectomy for Primary Open Angle Glaucoma (POAG), is a risk factor for future failure of the filter. METHODS: We performed a retrospective, case notes review, of patients who underwent trabeculectomy for POAG between Jan 1995 and Jan 1996 at our hospital. We identified those with postoperative hypotony within 1 month of surgery. Hypotony was defined as an intraocular pressure (IOP) < 8 mmHg or an IOP of less than 10 mmHg with choroidal detachment or a shallow anterior chamber. We compared the survival times of the surgery in this group with a control group (who did not suffer hypotony as described above), over a 5 year period. Failure of trabeculectomy was defined as IOP > 21 mmHg, or commencement of topical antihypertensives or repeat surgery. RESULTS: 97 cases matched our inclusion criteria, of these 38 (39%) experienced hypotony within 1 month of surgery. We compared the survival times in those patients who developed hypotony with those who did not using the log-rank test. This data provided evidence of a difference (P = 0.0492) with patients in the hypotony group failing more rapidly than the control group. CONCLUSION: Early post-trabeculectomy hypotony (within 1 month) is associated with reduced survival time of blebs

Comparative efficacy and safety of the fixed versus unfixed combination of latanoprost and timolol in Chinese patients with open-angle glaucoma or ocular hypertension

<p>Abstract</p> <p>Background</p> <p>A noninferiority trial was conducted to evaluate the efficacy of a single evening dose of fixed-combination latanoprost 50 μg/mL and timolol 0.5 mg/mL (Xalacom^®; LTFC), in Chinese patients with primary open-angle glaucoma (POAG) or ocular hypertension (OH) who were insufficiently controlled on β-blocker monotherapy or β-blocker-based dual therapy.</p> <p>Methods</p> <p>This 8-week, randomized, open-label, parallel-group, noninferiority study compared once-daily evening dosing of LTFC with the unfixed combination of latanoprost, one drop in the evening, and timolol, one drop in the morning (LTuFC). The primary efficacy endpoint was the mean change from baseline to week 8 in diurnal intraocular pressure (IOP; mean of 8 AM, 10 AM, 2 PM, 4 PM IOPs). LTFC was considered noninferior to LTuFC if the upper limit of the 95% confidence interval (CI) of the difference was < 1.5 mmHg (analysis of covariance).</p> <p>Results</p> <p>Baseline characteristics were similar for LTFC (N = 125; POAG, 70%; mean IOP, 25.8 mmHg) and LTuFC (N = 125; POAG, 69%; mean IOP, 26.0 mmHg). Mean diurnal IOP changes from baseline to week 8 were -8.6 mmHg with LTFC and -8.9 mmHg with LTuFC (between-treatment difference: 0.3 mmHg; 95%-CI, -0.3 to 1.0). Both treatments were well tolerated.</p> <p>Conclusions</p> <p>A single evening dose of LTFC was at least as effective as the unfixed combination of latanoprost in the PM and timolol in the AM in reducing IOP in Chinese subjects with POAG or OH whose IOP was insufficiently reduced with β-blocker monotherapy or β-blocker-based dual therapy. LTFC is an effective and well tolerated once-daily treatment for POAG and OH.</p> <p>Trial registration</p> <p>Clinicaltrials.gov registration: <a href="http://www.clinicaltrials.gov/ct2/show/NCT00219596">NCT00219596</a></p

Alterations of Blood Brain Barrier Function in Hyperammonemia: An Overview

Ammonia is a neurotoxin involved in the pathogenesis of neurological conditions associated with hyperammonemia, including hepatic encephalopathy, a condition associated with acute—(ALF) or chronic liver failure. This article reviews evidence that apart from directly affecting the metabolism and function of the central nervous system cells, ammonia influences the passage of different molecules across the blood brain barrier (BBB). A brief description is provided of the tight junctions, which couple adjacent cerebral capillary endothelial cells to each other to form the barrier. Ammonia modulates the transcellular passage of low-to medium-size molecules, by affecting their carriers located at the BBB. Ammonia induces interrelated aberrations of the transport of the large neutral amino acids and aromatic amino acids (AAA), whose influx is augmented by exchange with glutamine produced in the course of ammonia detoxification, and maybe also modulated by the extracellularly acting gamma-glutamyl moiety transferring enzyme, gamma-glutamyl-transpeptidase. Impaired AAA transport affects neurotransmission by altering intracerebral synthesis of catecholamines (serotonin and dopamine), and producing “false neurotransmitters” (octopamine and phenylethylamine). Ammonia also modulates BBB transport of the cationic amino acids: the nitric oxide precursor, arginine, and ornithine, which is an ammonia trap, and affects the transport of energy metabolites glucose and creatine. Moreover, ammonia acting either directly or in synergy with liver injury-derived inflammatory cytokines also evokes subtle increases of the transcellular passage of molecules of different size (BBB “leakage”), which appears to be responsible for the vasogenic component of cerebral edema associated with ALF

Consensus Recommendation for Mouse Models of Ocular Hypertension to Study Aqueous Humor Outflow and Its Mechanisms.

Due to their similarities in anatomy, physiology, and pharmacology to humans, mice are a valuable model system to study the generation and mechanisms modulating conventional outflow resistance and thus intraocular pressure. In addition, mouse models are critical for understanding the complex nature of conventional outflow homeostasis and dysfunction that results in ocular hypertension. In this review, we describe a set of minimum acceptable standards for developing, characterizing, and utilizing mouse models of open-angle ocular hypertension. We expect that this set of standard practices will increase scientific rigor when using mouse models and will better enable researchers to replicate and build upon previous findings

Escucha México, Estrategias Gráficas y Cultura Auditiva. Otoño 2022

Este reporte del PAP Escucha México, perteneciente al trabajo realizado durante el periodo de Otoño 2022, cuenta con información detallada sobre los resultados alcanzados en cada uno de los proyectos que integran esta organización en el período anteriormente establecido. Para este proceso en específico, se buscó enfocar la mayor cantidad de esfuerzos posibles a que el 4to Encuentro Internacional de Cultura Auditiva se desarrollara de la mejor forma posible, sin descuidar el trabajo que se siguió realizando en el resto de proyectos. Como resumen general, todos presentaron resultados positivos, pues se tuvo presencia importante en redes sociales, mejor que en periodos anteriores, además de que se combinaron esfuerzos para que el 4to Encuentro tuviera una difusión adecuada y alcanzara a la mayor cantidad de personas posibles, lo que a su vez resultó en eventos llenos de gente interesada en aprender sobre Cultura Auditiva y Discapacidad, ejes temáticos centrales de este PAP.ITESO, A.C

A comprehensive overview of radioguided surgery using gamma detection probe technology

The concept of radioguided surgery, which was first developed some 60 years ago, involves the use of a radiation detection probe system for the intraoperative detection of radionuclides. The use of gamma detection probe technology in radioguided surgery has tremendously expanded and has evolved into what is now considered an established discipline within the practice of surgery, revolutionizing the surgical management of many malignancies, including breast cancer, melanoma, and colorectal cancer, as well as the surgical management of parathyroid disease. The impact of radioguided surgery on the surgical management of cancer patients includes providing vital and real-time information to the surgeon regarding the location and extent of disease, as well as regarding the assessment of surgical resection margins. Additionally, it has allowed the surgeon to minimize the surgical invasiveness of many diagnostic and therapeutic procedures, while still maintaining maximum benefit to the cancer patient. In the current review, we have attempted to comprehensively evaluate the history, technical aspects, and clinical applications of radioguided surgery using gamma detection probe technology