Commentary: Could biomass fuel smoke cause anaemia and stunting in early childhood?
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Air Pollution, Indoor↗
Biomedical subjects
James Tielsch
Publications and source records attributed to James Tielsch.
Determinants of normal retinal nerve fiber layer thickness measured by Stratus OCT.
PURPOSE: To determine the effects of age, optic disc area, ethnicity, eye, gender, and axial length on the retinal nerve fiber layer (RNFL) in the normal human eye as measured by Stratus OCT (optical coherence tomography). DESIGN: Cross-sectional observational study. PARTICIPANTS: Three hundred twenty-eight normal subjects 18 to 85 years old. METHODS: Peripapillary Fast RNFL scans performed by Stratus OCT with a nominal diameter of 3.46 mm centered on the optic disc were performed on one randomly selected eye of each subject. MAIN OUTCOME MEASURES: Linear regression analysis of the effects of age, ethnicity, gender, eye, axial length, and optic disc area on peripapillary RNFL thickness. RESULTS: The mean RNFL thickness for the entire population was 100.1 microm (standard deviation, 11.6). Thinner RNFL measurements were associated with older age (P<0.001); being Caucasian, versus being either Hispanic or Asian (P = 0.006); greater axial length (P<0.001); or smaller optic disc area (P = 0.010). For every decade of increased age, mean RNFL thickness measured thinner by approximately 2.0 microm (95% confidence interval [CI], 1.2-2.8). For every 1-mm-greater axial length, mean RNFL thickness measured thinner by approximately 2.2 microm (95% CI, 1.1-3.4). For every increase in square millimeter of optic disc area, mean RNFL thickness increased by approximately 3.3 microm (95% CI, 0.6-5.6). Comparisons between ethnic groups revealed that Caucasians had mean RNFL values (98.1+/-10.9 microm) slightly thinner than those of Hispanics (103.7+/-11.6 microm; P = 0.022) or Asians (105.8+/-9.2 microm; P = 0.043). There was no relationship between RNFL thickness and eye or gender. CONCLUSIONS: Retinal nerve fiber layer thickness, as measured by Stratus OCT, varies significantly with age, ethnicity, axial length, and optic disc area. These variables may need to be taken into account when evaluating patients for diagnosis and follow-up of glaucoma, particularly at the lower boundary of the normal range. Due to the relatively small numbers of subjects of Asian and African descent in the normative database, conclusions regarding the effect of ethnicity should be interpreted with caution.
Adolescent↗
The effect of deforestation on the human-biting rate of Anopheles darlingi, the primary vector of Falciparum malaria in the Peruvian Amazon.
To examine the impact of tropical rain-forest destruction on malaria, we conducted a year-long study of the rates at which the primary malaria vector in the Amazon, Anopheles darlingi, fed on humans in areas with varying degrees of ecological alteration in the Peruvian Amazon. Mosquitoes were collected by human biting catches along the Iquitos-Nauta road at sites selected for type of vegetation and controlled for human presence. Deforested sites had an A. darlingi biting rate that was more than 278 times higher than the rate determined for areas that were predominantly forested. Our results indicate that A. darlingi displays significantly increased human-biting activity in areas that have undergone deforestation and development associated with road development.
Animals↗
Effect of periodic vitamin A supplementation on mortality and morbidity of human immunodeficiency virus-infected children in Uganda: A controlled clinical trial.
OBJECTIVE: We investigated whether vitamin A supplementation would decrease mortality and morbidity rates in children infected with the human immunodeficiency virus (HIV). METHODS: We conducted a randomized, double-blind, placebo-controlled clinical trial at Mulago Hospital, a large hospital that serves the urban and semiurban populations of Kampala, Uganda. One hundred eighty-one HIV-infected children were enrolled at 6 mo and randomized to receive vitamin A supplementation, 60 mg retinol equivalent, or placebo every 3 mo from ages 15 to 36 mo. Morbidity was assessed through a 7-d morbidity history every 3 mo, and vital events were measured. Children received daily trimethoprim-sulfamethoxazole prophylactic therapy. RESULTS: After age 15 mo, children were followed for a median of 17.8 mo (interquartile range = 11.1 to 21.0 mo). The trial was stopped when there was a new policy to implement a program of mass supplementation of vitamin A in the country. Mortality rates among 87 children in the vitamin A group and 94 children in the control group were 20.6% and 32.9%, respectively, yielding a relative risk of 0.54 (95% confidence interval, 0.30 to 0.98; P = 0.044) after adjusting for baseline weight-for-height Z score. Children who received vitamin A had lower modified point prevalences of persistent cough (odds ratio, 0.47; 95% confidence interval, 0.23 to 0.96; P = 0.038) and chronic diarrhea (odds ratio, 0.48; 95% confidence interval, 0.19 to 1.18; P = 0.11) and a shorter duration of ear discharge (P = 0.03). Vitamin A supplementation had no significant effect on modified point prevalences of fever, ear discharge, bloody stools, or hospitalizations. CONCLUSIONS: Vitamin A supplementation decreases mortality rate in HIV-infected children and should be considered in the care for these children in developing countries.
Anti-Infective Agents↗
A social model for health promotion for an aging population: initial evidence on the Experience Corps model.
This report evaluates whether a program for older volunteers, designed for both generativity and health promotion, leads to short-term improvements in multiple behavioral risk factors and positive effects on intermediary risk factors for disability and other morbidities. The Experience Corps(R) places older volunteers in public elementary schools in roles designed to meet schools' needs and increase the social, physical, and cognitive activity of the volunteers. This article reports on a pilot randomized trial in Baltimore, Maryland. The 128 volunteers were 60-86 years old; 95% were African American. At follow-up of 4-8 months, physical activity, strength, people one could turn to for help, and cognitive activity increased significantly, and walking speed decreased significantly less, in participants compared to controls. In this pilot trial, physical, cognitive, and social activity increased, suggesting the potential for the Experience Corps to improve health for an aging population and simultaneously improve educational outcomes for children.
Aged↗
The utilization of eye care services by persons with glaucoma in rural south India.
PURPOSE: To determine utilization of eye care services, in particular those relating to glaucoma, in a rural population of southern India aged 40 years or older. METHODS: A total of 5,150 subjects aged 40 years or older selected through a random cluster sampling technique from three districts in southern India underwent detailed ocular examinations for vision impairment, blindness, and ocular morbidity. Information regarding previous use of eye care services was collected from this population through a questionnaire administered by trained social workers prior to ocular examinations. RESULTS: One thousand eight hundred and twenty-seven persons (35.5%) gave a history of prior eye examinations, primarily from a general hospital (n = 1,073, 58.7%). Increasing age and education were associated with increased utilization of eye care services. Among the 3,323 persons who had never sought eye care, 912 (27.4%) had felt the need to have an eye examination but did not do so. Only one third of persons with vision impairment, cataracts, refractive errors, and glaucoma had previously utilized services. Of the 64 subjects diagnosed as having primary open-angle glaucoma, 32 (50%) had previously seen an ophthalmologist, but none had had an eye examination within 1 year before the study. Only six (19%) of the 32 had been diagnosed as having glaucoma (9% of all subjects found to have glaucoma in the survey). Thirteen (20.3%) of the 64 subjects were blind in either eye due to glaucoma, including one person who was bilaterally blind. CONCLUSIONS: A large proportion of persons in a rural population of southern India who require eye care are currently not utilizing existing eye care services. Strategies to improve the uptake of services are required to reduce the burden of blindness due to glaucoma in southern India.
Adult↗
Ultrasonographic biomicroscopy, Scheimpflug photography, and novel provocative tests in contralateral eyes of Chinese patients initially seen with acute angle closure.
OBJECTIVES: To compare ocular biometry of the contralateral eyes of individuals seen with acute angle closure (AAC) with eyes of population-based control subjects, and to assess novel provocative tests to study the mechanism of AAC. DESIGN: Prospective case-control study. PARTICIPANTS: Chinese persons seen as incident cases of AAC and Chinese population-based controls. METHODS: Slitlamp assessment, ultrasonographic biomicroscopy, Scheimpflug photography, and provocative testing were performed. MAIN OUTCOME MEASURES: Ocular biometric parameters including anterior chamber depth, limbal anterior chamber depth, axial length, lens thickness, and radius of corneal curvature were obtained. Ultrasonographic biomicroscopy parameters that include the angle-opening distance at 500 micro m and the angle-recess area were noted. Scheimpflug photography produced a single measure of angle width. RESULTS: Contralateral eyes of cases of AAC had shorter axial lengths, shallower anterior chamber depths, thicker lenses, and steeper radii of corneal curvature (P<.01). After adjusting for age and sex, cases had a mean adjusted axial length that was 1.2 mm shorter, an optical anterior chamber depth that was 0.63 mm shallower (24% shallower than controls), and lenses that were, on average, 0.35 mm thicker (P<.01). Furthermore, using multiple logistic regression to adjust for age and sex, patients with primary angle-closure glaucoma were 19 times as likely to have a shallower limbal anterior chamber depth (25%; 95% confidence interval, 8.3-45.2). Adjusting for age and sex, the mean angle-opening distance at 500 microm was 0.14 U less for cases, with a mean of 0.26 U in controls, making the angle-opening distance at 500 microm, on average, 54% less among cases. Scheimpflug photographs revealed an adjusted angle width of 21.6 degrees for controls and 15.1 degrees for cases (P<.05). Dynamic testing showed that the angle of control eyes tended to shallow less when going from light to dark and tended to open more when given 1 drop of pilocarpine hydrochloride. CONCLUSIONS: Contralateral eyes of individuals having an AAC attack tend to be shorter and have more crowded anterior segments than those of healthy controls. These static measures of ocular biometry indicate why some individuals are predisposed to AAC. Dynamic measures of the response to luminance changes and pilocarpine therapy indicate that differential reactions to these stimuli are also associated with an AAC attack.
Acute Disease↗