Accommodative facility training with a long term follow up in a sample of school aged children showing accommodative dysfunction

The primary aim of this project was to study the effect of flip lens-training on the accommodative function in a group of children with accommodative dysfunction and subjective symptoms such as asthenopia, headache, blurred vision, and avoidance of near activity. We also wanted to measure the accommodative facility among the children in comparison with a control group. Another aim of the study was whether flip lens-training increased accommodative facility, and to find out if it also had a positive effect on their asthenopia and related problems also in long term. Following the training period the accommodative facility and accommodative function significantly increased and two years after finishing the training period no child had regained any subjective symptoms and the objective findings were almost the same as at the end of facility training period. These results suggest that accommodative facility training is an efficient method built on loss of symptoms among children with accommodative infacility. This revised version was published online in July 2006 with corrections to the Cover Date.     

Renal Uptake,Excretion, and Retention of Mercury

A modification is proposed for the conventional pH stat assay for human plasma and erythrocyte cholinesterases. Principal advantages for the micromodification are smaller sample size afforded by collection of specimens in microhematocrit tubes and reduction in subsequent sample-handling time. Red blood cell (RBC) washing and recentrifugation steps are eliminated. Although the basic assay procedure remains unchanged, titration parameters are changed to accommodate smaller sample volumes. Results from either assay procedure are comparable, as shown by statistically significant regressions of micromodification assay data upon those of conventional pH stat procedure.     

Tritiated Methylmercury in the Brain of Squirrel Monkeys

? Tritiated methylmercury hydroxide (MeHgOH) with a specific activity of 306 curies/mol was synthesized by a Grignard reagent from tritiated methyl iodide with a yield of 70%. Tritiated MeHg was given to squirrel monkeys by stomach tube in weekly doses of 0.8 mg/kg. The animals were killed after one dose or six doses. The distribution of the substance in the brain was then studied by microautoradiography and by fractionation of brain tissue into cellular and subcellular fractions.

Part of the MeHg in the brain is in a water-soluble form. Methylmercury was found autoradiographically mainly in the neuropile of the cortex. At subtoxic dose (one dose), more protein-bound radioactivity was found in the glial fraction than in the neuronal fraction. At toxic dose (six doses), the protein-bound fraction of MeHg increased significantly (P<.02) in the neurons relative to nontoxic dose (one dose). Methylmercury was demonstrated autoradiographically in damaged neurons but not in undamaged neurons.     

Distribution and Metabolism of 2,4,5,2’, 5’-Pentachlorobiphenyl

Single doses of 2,4,5,2’,5’-pentachloro-biphenyl uniformly labeled with ¹⁴C have been administered intravenously and orally to mice. Whole-body autoradiograms and scintillation counting of tissue samples have shown that most radioactivity leaves the circulation for the tissues within one hour. Peak concentrations varied, being highest in brown fat, which after 24 hours comprised the major reservoir of the unchanged compound in the body. Radioactivity disappeared rather rapidly from most other tissues, although the longest retention occurred in bronchial epithelium and some parts of the renal tubules.

The excretion of radioactivity was mainly through the bile, into feces, with a half-time of six days. There was little unchanged compound in the feces, the major metabolite was a hydroxylated derivative, both free and conjugated.     

Effects of Prenatal and Postnatal Methylmercury Exposure From Fish Consumption on Neurodevelopment: Outcomes at 66 Months of Age in the Seychelles Child Development Study

Context.— Human neurodevelopmental consequences of exposure to methylmercury (MeHg) from eating fish remain a question of public health concern. Objective.— To study the association between MeHg exposure and the developmental outcomes of children in the Republic of Seychelles at 66 months of age. Design.— A prospective longitudinal cohort study. Participants.— A total of 711 of 779 cohort mother-child pairs initially enrolled in the Seychelles Child Development Study in 1989. Setting.— The Republic of Seychelles, an archipelago in the Indian Ocean where 85% of the population consumes ocean fish daily. Main Outcome Measures.— Prenatal and postnatal MeHg exposure and 6 age-appropriate neurodevelopmental tests: the McCarthy Scales of Children's Abilities, the Preschool Language Scale, the Woodcock-Johnson Applied Problems and Letter and Word Recognition Tests of Achievement, the Bender Gestalt test, and the Child Behavior Checklist. Results.— The mean maternal hair total mercury level was 6.8 ppm and the mean child hair total mercury level at age 66 months was 6.5 ppm. No adverse outcomes at 66 months were associated with either prenatal or postnatal MeHg exposure. Conclusion.— In the population studied, consumption of a diet high in ocean fish appears to pose no threat to developmental outcomes through 66 months of age.      

The Effect of Disease, Functional Status, and Relapses on the Utility of People with Multiple Sclerosis in the UK

OBJECTIVES: Because published utility estimates in multiple sclerosis (MS) are concentrated in people with moderate to severe disease severity and focus on specific types of MS, we conducted a cross-sectional study of people with MS to estimate the utility associated with disease, functional status as measured by the Adapted Patient Determined Disease Steps (APDDS) Scale, and relapse to enhance knowledge of the association of these factors and utility. METHODS: The study was conducted by a postal questionnaire sent to 12,968 people in a database managed by a UK charity (the MS Trust). Utility was assessed using the EQ-5D multiattribute utility scale. The APDDS is closely related to the more commonly reported Expanded Disability Status Scale (EDSS). RESULTS: A total of 2708 (20.9%) questionnaires were returned and 2048 (15.8%) respondents provided data suitable for analysis. The mean age of the sample was 51 years, and 22.5% of people were aged 60 years or more. Disease severity was concentrated in people with moderately severe MS (EDSS 4-6.5), with 21%, 60%, and 19% of people reporting mild, moderate, and severe disease, respectively. Results show that disease severity has an inverse relationship with utility. The mean utility is 0.491. Utility varies between 0.870 and -0.195 for EDSS states 0 and 9. Number of years since diagnosis, type of disease, and recent relapse status are also all significantly associated with utility. CONCLUSIONS: The results are comparable with previous published utility estimates. We have demonstrated a clear relationship between functional status, disease type, relapse status, duration of illness, and utility. As a set of coefficients, the utility estimates we have calculated may be used to compare the quality of life of people with MS with other illnesses and to inform future economic evaluations in MS.     

Clinical evaluation of an eccentric infrared photorefractor: the PowerRefractor

PURPOSE: To evaluate the viability of the PowerRefractor as a screening tool for examining refractive errors in large samples of children. METHODS: The variability of the PowerRefractor was estimated using four patients. The refractive error was determined using cyclopentolate and tropicamide as cycloplegic agents and compared to that determined in a non-cycloplegic situation. In a second study, the data provided by the PowerRefractor were compared to results obtained by autorefractor or retinoscopy for 150 children aged from 6 months to 5 years. RESULTS: Variability study. Statistical analysis showed a statistically significant difference between cycloplegic and non-cycloplegic refraction for spherical and cylindrical refractive errors (p<0.0001 in all cases). There was no significant difference between the measurements made using tropicamide and cyclopentolate (p=0.33 and p=0.18, respectively). Comparison study. In 142 of 150 patients the difference between data obtained by the PowerRefractor and an autorefractor was within 1 D (spherical equivalent). However, there was a considerable difference between the data generated by the two methods in the remaining eight patients (up to 16 D). CONCLUSIONS: The PowerRefractor proved to be a reliable tool for estimating refractive errors in young children. The apparatus is easy to handle and the simultaneous examination of both eyes makes the PowerRefractor ideal for obtaining data on refractive errors in large samples.     

Toxic effects on mouse bone marrow caused by inhalation of benzene

Male NMRI mice were exposed to benzene in air, concentrations ranging between 1–200 ppm. The following parameters in the bone marrows were examined:1. number of nucleated cells/tibia, 2. number of colony forming granulopoietic stem cells (CFU-C)/tibia, and 3. frequency of micronuclei in polychromatic erythrocytes.At continuous exposure as low benzene concentrations as 21 ppm during 4–10 days significantly affected the three parameters. Intermittent exposure (8 h/day, 5 days/week, 2 weeks) also resulted in measurable toxicity, particularly on number of CFU-C/tibia and frequency of micronuclei, at 21 ppm and higher doses. Short peak exposures had very limited effects but did increase the proliferation rate of the bone marrow, i.e., the number of CFU-C/10⁵ cells became elevated.