Sulfhydryl compounds and antioxidants inhibit cytotoxicity to outer hair cells of a gentamicin metabolite in vitro

Aminoglycoside antibiotics such as gentamicin have long been known to destroy cochlear and vestibular hair cells in vivo. In the cochlea outer hair cells are preferentially affected. In contrast, gentamicin will not damage outer hair cells in vitro unless it has been enzymatically converted to a cytotoxic metabolite. Several potential inhibitors of this enzymatic reaction were tested in an in vitro assay against outer hair cells isolated from the guinea pig cochlea. Viability of hair cells (viable cells as per cent of total number of cells observed) averaged about 70% under control conditions. Addition of metabolized gentamicin significantly reduced viability to less than 50% in one hour. Sulfhydryl compounds (glutathione, dithioerythritol) and antioxidants (vitamin C, phenylene diamine, trolox) prevented the cytotoxic actions of the gentamicin metabolite. Inhibitors of aminc oxidases and compounds reportedly protective against renal and acute lethal toxicity of aminoglycosides (poly--aspartate and pyridoxal phosphate, respectively) were ineffective as protectants. The results reinforce the hypothesis that gentamicin is enzymatically converted to a cytotoxin and imply the participation of sulfhydryl-sensitive groups or free radicals in this reaction. Alternatively or additionally, sulfhydryl compounds or antioxidants may participate in detoxification reactions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31500/1/0000422.pd

Decentralised Learning MACs for Collision-free Access in WLANs

By combining the features of CSMA and TDMA, fully decentralised WLAN MAC schemes have recently been proposed that converge to collision-free schedules. In this paper we describe a MAC with optimal long-run throughput that is almost decentralised. We then design two \changed{schemes} that are practically realisable, decentralised approximations of this optimal scheme and operate with different amounts of sensing information. We achieve this by (1) introducing learning algorithms that can substantially speed up convergence to collision free operation; (2) developing a decentralised schedule length adaptation scheme that provides long-run fair (uniform) access to the medium while maintaining collision-free access for arbitrary numbers of stations

A Study of the Safety and Efficacy of Travoprost 0.004%/Timolol 0.5% Ophthalmic Solution Compared to Latanoprost 0.005% and Timolol 0.5% Dosed Concomitantly in Patients with Open-Angle Glaucoma or Ocular Hypertension

Background/Aims: To compare the intraocular pressure (IOP)-lowering efficacy of travoprost 0.004%/timolol 0.5% in fixed combination with the unfixed combination of latanoprost 0.005% and timolol 0.5% in open-angle glaucoma or ocular hypertension patients with IOP levels below 18 mmHg on the unfixed combination of latanoprost 0.005% and timolol 0.5%. Methods: Following a 30-day open-label run-in with latanoprost QD PM and timolol QD AM, subjects with intraocular pressure below 18 mmHg were randomized to continue concomitant latanoprost QD PM and timolol QD AM or switch to travoprost 0.004%/timolol 0.5% QD AM and vehicle QD PM in masked fashion and were followed for 3 months. The primary efficacy endpoint was mean IOP reduction from baseline. Results: There were no clinically relevant or statistically significant differences in mean IOP, mean IOP change from baseline, or percentage IOP change from baseline between the two treatment groups. Between-group differences in mean IOP were within ±0.3 mmHg at all time points (p ≥ 0.384), and between-group differences in mean IOP change from baseline were within ±0.4 mmHg at all time points. Overall, 88% of patients whose IOP was less than 18 mmHg on the unfixed combination of latanoprost and timolol remained well controlled on the same regimen in the masked portion of the study, compared with 92% who remained well controlled after switching to travoprost/timolol. Conclusion: Travoprost 0.004%/timolol 0.5% administered once daily and concomitant administration of timolol 0.5% and latanoprost 0.005% produce similar maintenance of IOP-lowering effect in patients who were previously well controlled on concomitant administration of latanoprost and timolol. Patients who are well controlled on latanoprost and timolol concomitant therapy can be switched to once-daily therapy with travoprost 0.004%/timolol 0.5% with no expected compromise in the safety and efficacy of their treatment

A study of the safety and efficacy of travoprost 0.004%/timolol 0.5% ophthalmic solution compared to latanoprost 0.005% and timolol 0.5% dosed concomitantly in patients with open-angle glaucoma or ocular hypertension

Douglas J Rhee1, James H Peace2, Sushanta Mallick3, Theresa A Landry3, Michael VW Bergamini3, and the Study Group*1Massachusetts Eye and Ear Infirmary, Harvard University, Boston, MA, USA; 2Diabetic Eye Medical Clinic, Inglewood, CA, USA; 3Alcon Laboratories, Inc., Ft. Worth, TX, USA; *Study Group members listed in AppendixBackground/Aims: To compare the intraocular pressure (IOP)-lowering efficacy of travoprost 0.004%/timolol 0.5% in fixed combination with the unfixed combination of latanoprost 0.005% and timolol 0.5% in open-angle glaucoma or ocular hypertension patients with IOP levels below 18 mmHg on the unfixed combination of latanoprost 0.005% and timolol 0.5%.Methods: Following a 30-day open-label run-in with latanoprost QD PM and timolol QD AM, subjects with intraocular pressure below 18 mmHg were randomized to continue concomitant latanoprost QD PM and timolol QD AM or switch to travoprost 0.004%/timolol 0.5% QD AM and vehicle QD PM in masked fashion and were followed for 3 months. The primary efficacy endpoint was mean IOP reduction from baseline.Results: There were no clinically relevant or statistically significant differences in mean IOP, mean IOP change from baseline, or percentage IOP change from baseline between the two treatment groups. Between-group differences in mean IOP were within ±0.3 mmHg at all time points (p ≥ 0.384), and between-group differences in mean IOP change from baseline were within ±0.4 mmHg at all time points. Overall, 88% of patients whose IOP was less than 18 mmHg on the unfixed combination of latanoprost and timolol remained well controlled on the same regimen in the masked portion of the study, compared with 92% who remained well controlled after switching to travoprost/timolol.Conclusion: Travoprost 0.004%/timolol 0.5% administered once daily and concomitant administration of timolol 0.5% and latanoprost 0.005% produce similar maintenance of IOP-lowering effect in patients who were previously well controlled on concomitant administration of latanoprost and timolol. Patients who are well controlled on latanoprost and timolol concomitant therapy can be switched to once-daily therapy with travoprost 0.004%/timolol 0.5% with no expected compromise in the safety and efficacy of their treatment.Keywords: travoprost, timolol, glaucoma, intraocular pressure, fixed combinatio

Lack of Association of Polymorphisms in Homocysteine Metabolism Genes with Pseudoexfoliation Syndrome and Glaucoma

Purpose: To evaluate genes involved in homocysteine metabolism as secondary risk factors for pseudoexfoliation syndrome (PXFS) and the associated glaucoma (PXFG). Methods: One hundred eighty-six unrelated patients with PXFS, including 140 patients with PXFG and 127 unrelated control subjects were recruited from the Massachusetts Eye and Ear Infirmary. All the patients and controls were Caucasian of European ancestry. Seventeen tag SNPs from 5 genes (methylenetetrahydrofolate reductase [MTHFR], methionine synthase [MTR], methionine synthase reductase [MTRR], methylenetetrahydrofolate dehydrogenase [MTHFD1], and cystathionine β-synthase [CBS]) were genotyped. Single-SNP association was analyzed using Fisher’s exact test (unconditional) or logistic regression after conditioning on the effects of age and three LOXL1 SNPs (rs1048661, rs3825942, and rs2165241). Interaction analysis was performed between the homocysteine and LOXL1 SNPs using logistic regression. Haplotype analysis and the set-based test were used to test for association of individual genes. Multiple comparisons were corrected using the Bonferroni method. Results: One SNP (rs8006686) in MTHFD1 showed a nominally significant association with PXFG (p=0.015, OR=2.23). None of the seventeen SNPs tested were significantly associated with PXFS or PXFG after correcting for multiple comparisons (Bonferroni corrected p>0.25). After controlling for the effects of age and three associated LOXL1 SNPs, none of the seventeen tested SNPs were associated with PXFS (p>0.12). No significant interaction effects on PXFS were identified between the homocysteine and LOXL1 SNPs (p>0.06). Haplotype analysis and the set-based test did not find significant association of individual genes with PXFS (p>0.23 and 0.20, respectively). Conclusions: Five genes that are critical components of the homocysteine metabolism pathway were evaluated as secondary factors for PXFS and PXFG. Our results suggest that these genes are not significant risk factors for the development of these conditions

A Cross-Sectional Survey of the Association between Bilateral Topical Prostaglandin Analogue Use and Ocular Adnexal Features

We studied the relation between prostaglandin analogue use and ocular adnexal features. We used a prospective, cross-sectional study involving 157 current, 15 past, and 171 never users of prostaglandin analogues. Patients 50 years of age or older and without conditions affecting ocular adnexal anatomy underwent glaucoma medication use history, external digital photography and systematic external adnexal exam. Two masked readers assessed the digital photos for upper lid dermatochalasis and lower lid steatoblepharon using a validated grading scheme. Another masked clinical examiner also assessed upper lid ptosis, levator muscle function, and inferior scleral show. We performed ordinal logistic regression analysis accounting for multiple covariates to assess the relation between prostaglandin analogue use and adnexal features. Multivariable analyses indicated there was a 230-fold increased risk of incremental involution of dermatochalasis (odds ratio (OR) = 2.30; 95% confidence interval (CI) 1.43–3.69; p = 5.44E-04) and a 249-fold increased risk of incremental loss of lower lid steatoblepharon (OR = 2.49; 95% CI, 1.54–4.03; p = 1.98E-04) associated with current prostaglandin analogue use (bimatoprost 0.03%, travoprost 0.005%, or latanoprost 0.004%) versus prostaglandin analogue never or past users. Upper lid ptosis (OR = 4.04; 95% CI, 2.43–6.72; p = 7.37E-08), levator dysfunction (OR = 7.51; 95% CI, 3.39–16.65; p = 6.74E-07) and lower lid retraction (OR = 2.60; 95% CI, 1.58–4.28; p = 1.72E-04) were highly associated with current prostaglandin analogue use versus prostaglandin analogue never or past users. The associations between prostaglandin analogue use and deepening of the upper lid sulci and between prostaglandin analogue use and loss of inferior periorbital fat are confirmed in this multivariable analysis. The associations between prostaglandin analogue use and levator muscle dysfunction and between prostaglandin analogue use and upper lid ptosis represent significant side effects that could impact visual function in glaucoma patients

Outflow Facility Effects of 3 Schlemm’s Canal Microinvasive Glaucoma Surgery Devices

Purpose To study the effect of 3 Schlemm’s canal (SC) microinvasive glaucoma surgery (MIGS) devices on outflow facility. Design Paired comparisons, randomized design, baseline-controlled study. Participants Thirty-six pairs of dissected anterior segments from donated human eye bank eyes without glaucoma were studied. A baseline measurement was collected from each eye to serve as its control. Methods Using a constant pressure perfusion method, outflow facility was measured in paired eyes from human donors. Measurements were made at perfusion pressures of 10 mmHg, 20 mmHg, 30 mmHg, and 40 mmHg. Outflow facility was measured before (baseline control) and after the implantation of an SC glaucoma drainage device or sham procedure. Three sets of experiments were carried out comparing 1 and 2 iStent Trabecular Micro-Bypass Stents and 2 iStent Inject implants with the Hydrus Microstent. Main Outcome Measures Change in outflow facility from baseline or contralateral eye. Results After Hydrus placement, the outflow facility increased from 0.23±0.03 μl/minute per millimeter of mercury at baseline to 0.38±0.03 μl/minute per millimeter of mercury (P < 0.001). The percent increase in outflow facility was 79±21% for the Hydrus and 11±16% for the 2 iStent Inject devices, a difference that was significant (P = 0.018). Outflow facility with 1 iStent (0.38±0.07 μl/minute per millimeter of mercury) was greater than baseline (0.28±0.03 μl/minute per millimeter of mercury; P = 0.031). The 1 iStent showed a greater increase in outflow facility from baseline (0.10±0.04 μl/minute per millimeter of mercury) compared with the sham procedure (–0.08±0.05 μl/minute per millimeter of mercury; P = 0.042). No other significant differences were found. Conclusions The longer the MIGS device, and thus the more SC that it dilates, the greater the outflow facility

Evaluation of SPARC as a candidate gene of juvenile-onset primary open-angle glaucoma by mutation and copy number analyses

Purpose: To investigate the involvement of SPARC (secreted protein acidic and rich in cysteine) mutations and copy number variation in juvenile-onset primary open-angle glaucoma (JPOAG). Methods: This study involved the 27 family members from the GLC1M (glaucoma 1, open angle, M)-linked Philippine pedigree with JPOAG, 46 unrelated Chinese patients with JPOAG and 95 controls. Mutation screening of the SPARC sequence, covering the promoter, 5′-untranslated region (UTR), entire coding regions, exon-intron boundaries, and part of the 3′-UTR, was performed using polymerase chain reaction and direct DNA sequencing. Copy number of the gene was analyzed by three TaqMan copy number assays. Results: No putative SPARC mutation was detected in the Philippine family. In the Chinese participants, 11 sequence variants were detected. Two were novel: IVS2+8G>T and IVS2+32C>T. For the 9 known SNPs, one was synonymous (rs2304052, p.Glu22Glu) and the others were located in noncoding regions. No individual SNP was associated with JPOAG. Five of the most common SNPs, i.e., rs2116780, rs1978707, rs7719521, rs729853, and rs1053411, were contained in a LD (linkage disequilibrium) block. Haplotype-based analysis showed that no haplotype was associated with the disorder. Copy number analysis revealed that all study subjects had two copies of the gene, suggesting no correlation between the copy number of SPARC and JPOAG. Conclusions: We have excluded SPARC as the causal gene at the GLC1M locus in the Philippine pedigree and, for the first time, revealed that the coding sequences, splice sites and copy number of SPARC do not contribute to JPOAG. Further investigations are warranted to unravel the involvement of SPARC in the pathogenesis of other forms of glaucoma

Drug Resistance Mutations for Surveillance of Transmitted HIV-1 Drug-Resistance: 2009 Update

Programs that monitor local, national, and regional levels of transmitted HIV-1 drug resistance inform treatment guidelines and provide feedback on the success of HIV-1 treatment and prevention programs. To accurately compare transmitted drug resistance rates across geographic regions and times, the World Health Organization has recommended the adoption of a consensus genotypic definition of transmitted HIV-1 drug resistance. In January 2007, we outlined criteria for developing a list of mutations for drug-resistance surveillance and compiled a list of 80 RT and protease mutations meeting these criteria (surveillance drug resistance mutations; SDRMs). Since January 2007, several new drugs have been approved and several new drug-resistance mutations have been identified. In this paper, we follow the same procedures described previously to develop an updated list of SDRMs that are likely to be useful for ongoing and future studies of transmitted drug resistance. The updated SDRM list has 93 mutations including 34 NRTI-resistance mutations at 15 RT positions, 19 NNRTI-resistance mutations at 10 RT positions, and 40 PI-resistance mutations at 18 protease positions