Low frequency of myocilin mutations in Indian primary open-angle glaucoma patients

Glaucoma is one of the major causes of blindness in the Indian population. Mutations in the myocilin (MYOC) gene have been reported in different populations. However, reports on MYOC mutations in Indian primary open-angle glaucoma (POAG) patients and juvenile open-angle glaucoma (JOAG) patients are sparse. We therefore screened 100 unrelated POAG/JOAG patients for MYOC mutations. Patients with POAG/JOAG were clinically diagnosed. Genomic DNA from such patients was collected and studied for MYOC mutations by direct sequencing. Nucleotide variations were compared with unrelated healthy controls by restriction enzyme digestion. Secondary structure prediction for the sequence variants was performed by Chou-Fasman method. A novel mutation in exon 1 (144 G-->Alpha) resulting in Gln48His substitution was observed in 2% of the patients. Four other polymorphisms were also observed. The novel mutation was seen in four other affected family members of a JOAG patient. The novel mutation was found to alter the secondary structure in the glycosaminoglycan initiation site of the protein. MYOC mutations were found in 2% of the population studied. MYOC gene may not be playing a significant role in causing POAG in the Indian population.     

4-Tertiary butyl phenol exposure sensitizes human melanocytes to dendritic cell-mediated killing: relevance to vitiligo

The trigger initiating an autoimmune response against melanocytes in vitiligo remains unclear. Patients frequently experience stress to the skin prior to depigmentation. 4-tertiary butyl phenol (4-TBP) was used as a model compound to study the effects of stress on melanocytes. Heat shock protein (HSP)70 generated and secreted in response to 4-TBP was quantified. The protective potential of stress proteins generated following 4-TBP exposure was examined. It was studied whether HSP70 favors dendritic cell (DC) effector functions as well. Melanocytes were more sensitive to 4-TBP than fibroblasts, and HSP70 generated in response to 4-TBP exposure was partially released into the medium by immortalized vitiligo melanocyte cell line PIG3V. Stress protein HSP70 in turn induced membrane tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) expression and activation of DC effector functions towards stressed melanocytes. Melanocytes exposed to 4-TBP demonstrated elevated TRAIL death receptor expression. DC effector functions were partially inhibited by blocking antibodies to TRAIL. TRAIL expression and infiltration by CD11c+ cells was abundant in perilesional vitiligo skin. Stressed melanocytes may mediate DC activation through release of HSP70, and DC effector functions appear to play a previously unappreciated role in progressive vitiligo.     

Electrophysiological evidence for heterogeneity of lesions in optic neuritis

PURPOSE: To examine the natural history of multifocal visual evoked potentials (mfVEPs) within 12 months of the first episode of optic neuritis (ON) in patients with possible multiple sclerosis (MS). METHODS: Twenty-seven patients with a first episode of ON, no previous demyelinating events, and MRI lesions consistent with demyelination were examined with mfVEP. Changes in amplitude and latency of mfVEP were analyzed at 1, 3, 6, and 12 months after an acute attack. RESULTS: Five of 27 patients had persistent loss of amplitude after 12 months of follow-up. This loss was most marked centrally. Amplitude recovered in the remaining 22 patients at 1 month, but delayed latency, which was also most marked centrally, persisted. Of these, two distinct subgroups were identified: six patients with no improvement in latency and 16 patients with significant latency recovery over the 12 months of follow-up, suggesting remyelination. Conversion to MS was highest in the group with severe amplitude loss, followed by the group with no latency recovery. The conversion rate was lowest in the group of patients with latency improvement. CONCLUSIONS: Distinct patterns of disease evolution were identified using mfVEP in patients with first episode of optic neuritis and at high risk for MS, supporting the concept of heterogeneity of early lesions in MS.     

Tumor targeting by covalent conjugation of a natural fatty acid to paclitaxel.

Certain natural fatty acids are taken up avidly by tumors for use as biochemical precursors and energy sources. We tested in mice the hypothesis that the conjugation of docosahexaenoic acid (DHA), a natural fatty acid, and an anticancer drug would create a new chemical entity that would target tumors and reduce toxicity to normal tissues. We synthesized DHA-paclitaxel, a 2'-O-acyl conjugate of the natural fatty acid DHA and paclitaxel. The data show that the conjugate possesses increased antitumor activity in mice when compared with paclitaxel. For example, paclitaxel at its optimum dose (20 mg/kg) caused neither complete nor partial regressions in any of 10 mice in a Madison 109 (M109) s.c. lung tumor model, whereas DHA-paclitaxel caused complete regressions that were sustained for 60 days in 4 of 10 mice at 60 mg/kg, 9 of 10 mice at 90 mg/kg, and 10 of 10 mice at the optimum dose of 120 mg/kg. The drug seems to be inactive as a cytotoxic agent until metabolized by cells to an active form. The conjugate is less toxic than paclitaxel, so that 4.4-fold higher molar doses can be delivered to mice. DHA-paclitaxel in rats has a 74-fold lower volume of distribution and a 94-fold lower clearance rate than paclitaxel, suggesting that the drug is primarily confined to the plasma compartment. DHA-paclitaxel is stable in plasma, and high concentrations are maintained in mouse plasma for long times. Tumor targeting of the conjugate was demonstrated by pharmacokinetic studies in M109 tumor-bearing mice, indicating an area under the drug concentration-time curve of DHA-paclitaxel in tumors that is 8-fold higher than paclitaxel at equimolar doses and 57-fold higher at equitoxic doses. At equimolar doses, the tumor area under the drug concentration-time curve of paclitaxel derived from i.v. DHA-paclitaxel is 6-fold higher than for paclitaxel derived from i.v. paclitaxel. Even at 2 weeks after treatment, 700 nM paclitaxel remains in the tumors after DHA-paclitaxel treatment. Low concentrations of DHA-paclitaxel or paclitaxel derived from DHA-paclitaxel accumulate in gastrocnemius muscle; which may be related to the finding that paclitaxel at 20 mg/kg caused hind limb paralysis in nude mice, whereas DHA-paclitaxel caused none, even at doses of 90 or 120 mg/kg. The dose-limiting toxicity in rats is myelosuppression, and, as in the mouse, little DHA-paclitaxel is converted to paclitaxel in plasma. Because DHA-paclitaxel remains in tumors for long times at high concentrations and is slowly converted to cytotoxic paclitaxel, DHA-paclitaxel may kill those slowly cycling or residual tumor cells that eventually come into cycle.     

Outcomes of cataract surgery in a rural and urban south Indian population

Purpose:

To assess the visual outcome after cataract surgery in a south Indian population.

Materials and Methods:

Population-based cross-sectional study of subjects aged 40 years or more. Three thousand nine hundred and twenty-four rural subjects from 27 contiguous villages and 3850 urban subjects from five randomly selected divisions were studied. All subjects underwent a comprehensive ophthalmic examination that included visual acuity, refraction, slit-lamp biomicroscopy, applanation tonometry, gonioscopy, and dilated retinal examination.

Statistical Analysis:

Chi square test, t test and multivariate analysis were used.

Results:

Five hundred and twenty-eight (216 males, 312 females, 781 eyes) rural subjects (13.5%, 95% confidence interval (CI) 12.4% to 14.6%) and 406 (197 males, 209 females, 604 eyes) urban subjects (10.5%, 95% CI 9.6-11.5%) had undergone cataract surgery. Outcome of cataract surgery was defined based on visual acuity. Using best-corrected visual acuity for classification, the single most important cause for visual impairment was cystoid macular edema in the aphakic group and posterior capsule opacification in the pseudophakic group. Aphakia (visual acuity of <20/60 to ≤20/400 - odds ratio (OR) 1.8; 95% CI 1.3 to 2.6%, visual acuity of <20/400 - OR 6.2; 95% 4.0 to 9.8%), rural residence (visual acuity of <20/60 to ≤20/400 - OR 3.2; 95% CI 2.2 to 4.5% and visual acuity of <20/400 - OR OR 3.5; 95% CI 2.3 to 5.5%) were associated with visual impairment. The urban cataract-operated population had significantly more pseudophakics (P < 0.001), men (P = 0.02) and literates (P < 0.001). In the rural group the prevalence of cataract surgery (13.5% vs. 10.5%, P < 0.001) and number of people that had undergone cataract surgery within three years prior to examination (P < 0.001) were significantly greater. In 30% of rural and 16% of urban subjects uncorrected refraction was the cause of visual impairment.

Conclusions:

Surgery-related complications were major causes for visual acuity of <20/60.     

Dichoptic stimulation improves detection of glaucoma with multifocal visual evoked potentials

PURPOSE: To determine whether simultaneous binocular (dichoptic) stimulation for multifocal visual evoked potentials (mfVEP) detects glaucomatous defects and decreases intereye variability. METHODS: Twenty-eight patients with glaucoma and 30 healthy subjects underwent mfVEP on monocular and dichoptic stimulation. Dichoptic stimulation was presented with the use of virtual reality goggles (recording time, 7 minutes). Monocular mfVEPs were recorded sequentially for each eye (recording time, 10 minutes). RESULTS: Comparison of mean relative asymmetry coefficient (RAC; calculated as difference in amplitudes between eyes/sum of amplitudes of both eyes at each segment) on monocular and dichoptic mfVEP revealed significantly lower RAC on dichoptic (0.003 +/- 0.03) compared with monocular testing (-0.02 +/- 0.04; P = 0.002). In all 28 patients, dichoptic mfVEP identified defects with excellent topographic correspondence. Of 56 hemifields (28 eyes), 33 had Humphrey visual field (HFA) scotomas, all of which were detected by dichoptic mfVEP. Among 23 hemifields with normal HFA, two were abnormal on monocular and dichoptic mfVEP. Five hemifields (five patients) normal on HFA and monocular mfVEP were abnormal on dichoptic mfVEP. In all five patients, corresponding rim changes were observed on disc photographs. Mean RAC of glaucomatous eyes was significantly higher on dichoptic (0.283 +/- 0.18) compared with monocular (0.199 +/- 0.12) tests (P = 0.0006). CONCLUSIONS: Dichoptic mfVEP not only detects HFA losses, it may identify early defects in areas unaffected on HFA and monocular mfVEP while reducing testing time by 30%. Asymmetry was tighter among healthy subjects but wider in patients with glaucoma on simultaneous binocular stimulation, which is potentially a new tool in the early detection of glaucoma.