Photosynthesis dependent acidification of perialgal vacuoles in theParamedum bursaria/Chlorella symbiosis. Visualization by monensin

After treatment with the carboxylic ionophore monensin theChlorella containing perialgal vacuoles of the greenParamecium bursaria swell. TheParamecium cells remain motile at this concentration for at least one day. The swelling is only observed in illuminated cells and can be inhibited by DCMU. We assume that during photosynthesis the perialgal vacuoles are acidified and that monensin exchanges H+ ions against monovalent cations (here K+). In consequence the osmotic value of the vacuoles increases. The proton gradient is believed to drive the transport of maltose from the symbiont into the host. Another but light independent effect of the monensin treatment is the swelling of peripheral alveoles of the ciliates, likewise indicating that the alveolar membrane contains an active proton pump

Genetic deficiency of aldose reductase counteracts the development of diabetic nephropathy in C57BL/6 mice

National Science Foundation of China [30770490]; 973 Program of China [2009CB941601]; Science Planning Program of Fujian Province [2009J1010]; Natural Science Foundation of Fujian Province [2009J01180]; Fujian Provincial Department of Science and TechnoloThe aim of the study was to investigate the effects of genetic deficiency of aldose reductase in mice on the development of key endpoints of diabetic nephropathy. A line of Ar (also known as Akr1b3)-knockout (KO) mice, a line of Ar-bitransgenic mice and control C57BL/6 mice were used in the study. The KO and bitransgenic mice were deficient for Ar in the renal glomeruli and all other tissues, with the exception of, in the bitransgenic mice, a human AR cDNA knockin-transgene that directed collecting-tubule epithelial-cell-specific AR expression. Diabetes was induced in 8-week-old male mice with streptozotocin. Mice were further maintained for 17 weeks then killed. A number of serum and urinary variables were determined for these 25-week-old mice. Periodic acid-Schiff staining, western blots, immunohistochemistry and protein kinase C (PKC) activity assays were performed for histological analyses, and to determine the levels of collagen IV and TGF-beta 1 and PKC activities in renal cortical tissues. Diabetes-induced extracellular matrix accumulation and collagen IV overproduction were completely prevented in diabetic Ar-KO and bitransgenic mice. Ar deficiency also completely or partially prevented diabetes-induced activation of renal cortical PKC, TGF-beta 1 and glomerular hypertrophy. Loss of Ar results in a 43% reduction in urine albumin excretion in the diabetic Ar-KO mice and a 48% reduction in the diabetic bitransgenic mice (p < 0.01). Genetic deficiency of Ar significantly ameliorated development of key endpoints linked with early diabetic nephropathy in vivo. Robust and specific inhibition of aldose reductase might be an effective strategy for the prevention and treatment of diabetic nephropathy

Relationship between proteins encoded by three human gamma-crystallin genes and distinct polypeptides in the eye lens.

Although individual gamma-crystallins from the human eye lens have not been successfully purified and sequenced, most of the genes coding for these lens-specific structural proteins have been cloned and characterized. To investigate the relationship between these genes and the gamma-crystallins of the human lens, we made use of mouse cell lines which contain stably integrated copies of the coding sequences for three of the human gamma-crystallin genes coupled to the human metallothionein IIA promoter. The proteins produced by these hybrid genes in cell culture were detected immunologically and compared by physical characteristics with the gamma-crystallins from the human lens. The protein encoded by the G3 gene showed properties identical to those of the 21,000-molecular-weight gamma-crystallin from 11-month-old lens. The protein isolated from the cells expressing the G4 gene was similar to a 19,000-molecular-weight lens gamma-crystallin, while gene G5 encodes a highly basic gamma-crystallin which may be synthesized in only limited amounts in the human lens. These correlations provide a basis for future investigations on the relationship between putative mutations in human gamma-crystallin genes and altered proteins in hereditary lens cataracts.link_to_OA_fulltex

The efficacy of tolrestat in the treatment of diabetic peripheral neuropathy. A meta-analysis of individual patient data.

OBJECTIVE: The aim of this meta-analysis was to review the existent evidence on the effectiveness of tolrestat in the treatment of diabetic peripheral neuropathy. RESEARCH DESIGN AND METHODS: Individual patient data on 738 subjects from the three randomized clinical trials published on this topic were analyzed using changes in motor nerve conduction velocities (NCVs) as endpoints. Nerves investigated included median, ulnar, tibial, and peroneal. RESULTS: The pooled analysis of NCV taken as a continuous measurement showed a significant treatment effect, the magnitude of this benefit being approximately equal to 1 m/s for all the nerves investigated. When looking at the proportion of patients experiencing a loss of NCV of at least 1 or 2 m/s in at least two out of the four nerves investigated, it emerged that treatment reduced by > 40% the risk of such outcomes after adjusting for patients' characteristics. The odds ratios relative to the placebo group were 1.82 (1.30-2.52) and 1.70 (1.15-2.48) for a decrease of 1 and 2 m/s, that is, placebo-treated patients have an 82 and 70% increased risk for a loss of nerve function of 1 and 2 m/s, respectively. No statistically significant difference in treatment effect emerged after stratification according to baseline motor NCV and glycated hemoglobin levels. CONCLUSIONS: After a treatment duration ranging between 24-52 weeks, patients treated with tolrestat had a reduced risk for developing nerve function loss compared with placebo-treated patients. Future long-term trials are needed to evaluate the impact of the treatment on more clinically meaningful endpoints such as the development of foot complications

The efficacy of tolrestat in the treatment of diabetic peripheral neuropathy. A meta-analysis of individual patient data.

OBJECTIVE: The aim of this meta-analysis was to review the existent evidence on the effectiveness of tolrestat in the treatment of diabetic peripheral neuropathy. RESEARCH DESIGN AND METHODS: Individual patient data on 738 subjects from the three randomized clinical trials published on this topic were analyzed using changes in motor nerve conduction velocities (NCVs) as endpoints. Nerves investigated included median, ulnar, tibial, and peroneal. RESULTS: The pooled analysis of NCV taken as a continuous measurement showed a significant treatment effect, the magnitude of this benefit being approximately equal to 1 m/s for all the nerves investigated. When looking at the proportion of patients experiencing a loss of NCV of at least 1 or 2 m/s in at least two out of the four nerves investigated, it emerged that treatment reduced by > 40% the risk of such outcomes after adjusting for patients' characteristics. The odds ratios relative to the placebo group were 1.82 (1.30-2.52) and 1.70 (1.15-2.48) for a decrease of 1 and 2 m/s, that is, placebo-treated patients have an 82 and 70% increased risk for a loss of nerve function of 1 and 2 m/s, respectively. No statistically significant difference in treatment effect emerged after stratification according to baseline motor NCV and glycated hemoglobin levels. CONCLUSIONS: After a treatment duration ranging between 24-52 weeks, patients treated with tolrestat had a reduced risk for developing nerve function loss compared with placebo-treated patients. Future long-term trials are needed to evaluate the impact of the treatment on more clinically meaningful endpoints such as the development of foot complications

Reticular drusen associated with geographic atrophy in age-related macular degeneration.

PURPOSE: To characterize reticular drusen (RDR) in patients with geographic atrophy (GA) secondary to age-related macular degeneration (AMD) in a prospective, multicenter, natural history study. METHODS: Confocal scanning laser ophthalmoscopy (cSLO) three-field fundus autofluorescence (FAF; exc., 488; em., 500-700 nm), near-infrared reflectance (IR; 820 nm), and blue reflectance (BR; 488 nm) images as well as red-free (RF) and color fundus (CF) camera photographs were recorded in 458 GA patients. The digital images were evaluated by two independent readers with subsequent senior reader arbitration for prevalence and topographic distribution of RDR using a modified Early Treatment Diabetic Retinopathy Study grid. RESULTS: RDR were detected with at least one cSLO modality in 286 of 458 (62%) patients in either eye (bilateral 207 [45%]) and were visible in fundus camera photographs in 66 of 371 (18%) patients (bilateral 48 [13%]). Prevalence of RDR by cSLO imaging was associated with increasing age (P = 0.007) and female sex (P = 0.007), but not with GA total lesion area (P = 0.38). Cohen kappa statistics showed good interobserver agreement for FAF (0.81) and IR (0.82) imaging modes, and moderate agreement was found for BR (0.48), RF (0.48), and CF (0.40). On three-field FAF images RDR were present most frequently superior to the fovea (99%). CONCLUSIONS: RDR represent a common phenotypic hallmark in GA eyes. RDR are readily identified using cSLO imaging technology. These observations may explain the high prevalence determined herein, in contrast to previous reports based on fundus photographs. Incorporation of these novel imaging modalities in future natural history studies may facilitate efforts aimed at defining the role and predictive value of RDR in the progression of AMD. (ClinicalTrials.gov number, NCT00599846.