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Biomedical subjects

A Sommer

Publications and source records attributed to A Sommer.

At least 217 records · Page 12Linked to original sources
PubMed1992

Tolerance of young infants to a single, large dose of vitamin A: a randomized community trial in Nepal.

A randomized, double-masked trial was carried out in rural Nepal to investigate the incidence and severity of acute side-effects among neonates ( < 1 month of age) and infants aged 1-6 months who received a large, oral dose of vitamin A (15,000 retinol equivalents (RE) (50,000 IU) and 30,000 RE (100,000 IU), respectively) or placebo (75 RE (250 IU) and 150 RE (500 IU), respectively) in oil. Infants (vitamin A group, n = 1461; controls, n = 1379) were assessed for vomiting, loose stools, fever, and irritability during the 24 hours before and after dosing. Fontanelles were palpated 24 hours after dosing. Neonates exhibited no excess risk of adverse side-effects after receiving 15,000 RE. Compared with controls the older infants who ingested 30,000 RE had a 1.6% excess rate of vomiting (95% confidence interval (CI): 0.2-3.0%) and a 0.5% excess rate (95% CI: -0.1 to 1.1%) in the occurrence of bulging fontanelles. There were no other significant differences in the older infants. The controlled, periodic distribution of a single 15,000 RE dose of vitamin A therefore confers no apparent acute risk to young infants; a 30,000 RE dose is associated with a minimum risk of transient, acute side-effects.

Age Factors↗
PubMed1992

Vitamin A deficiency and attributable mortality among under-5-year-olds.

Reported are estimates of the prevalence in developing countries of physiologically significant vitamin A deficiency and the number of attributable deaths. The WHO classification of countries by the severity and extent of xerophthalmia was used to categorize developing countries by likely risk of subclinical vitamin A deficiency. Using vital statistics compiled by UNICEF, we derived population figures and mortality rates for under-5-year-olds. The findings of vitamin A supplementation trials were applied to populations at-risk of endemic vitamin A deficiency to estimate the potential impact of improved vitamin A nutriture in reducing mortality during preschool years. Worldwide, over 124 million children are estimated to be vitamin A deficient. Improved vitamin A nutriture would be expected to prevent approximately 1-2 million deaths annually among children aged 1-4 years. An additional 0.25-0.5 million deaths may be averted if improved vitamin A nutriture can be achieved during the latter half of infancy. Improved vitamin A nutriture alone could prevent 1.3-2.5 million of the nearly 8 million late infancy and preschool-age child deaths that occur each year in the highest-risk developing countries.

Age Factors↗
PubMed1991

Sulfhydryl-selective fluorescence labeling of lipoprotein(a) reveals evidence for one single disulfide linkage between apoproteins(a) and B-100.

Human lipoprotein(a) and low-density lipoprotein were labeled with two different sulfhydryl-selective fluorescence markers. The hydrophilic fluorophore lucifer yellow iodoacetamide and the apolar compound 6-acryloyl-2-(dimethylamino)naphthalene were used to derivatize free -SH groups in the lipoproteins. Three sulfhydryls could be detected in low-density lipoprotein, whereas only two cysteines were available in lipoprotein(a). One of the three -SH groups in low-density lipoprotein was shown to be located in close proximity to the particle surface. We suggest that this surface-exposed cysteine of apoprotein B-100 serves as a component for the disulfide linkage to apoprotein(a) in lipoprotein(a).

2-Naphthylamine↗
PubMed1991

A population-based evaluation of glaucoma screening: the Baltimore Eye Survey.

The Baltimore Eye Survey was a population-based survey conducted from January 1985 to November 1988 among residents of east Baltimore, Maryland, who were 40 years of age or older. A total of 5,308 black subjects and white subjects received a comprehensive screening examination for glaucoma including tonometry, visual fields, stereoscopic fundus photography, and a detailed medical and ophthalmic history. Based on a definitive examination, a diagnosis of glaucoma of any type was made for 196 persons. Tonometry, cup:disc ratio, and narrowest neuroretinal rim width were evaluated for their ability to correctly classify subjects into diseased or nondiseased states. There were no cutoff values at which these variables provided a reasonable balance of sensitivity and specificity, separately or in combination. Logistic regression models were fit that included demographic and other risk factors. Sensitivities and specificities were calculated for varying cutoff levels on the distribution of predicted probabilities. There was no cutoff for which reasonable sensitivity and specificity were obtained. The authors conclude that the effectiveness of current techniques for glaucoma screening is limited.

Adult↗
PubMed1991

Racial differences in the cause-specific prevalence of blindness in east Baltimore.

BACKGROUND: Bilateral blindness unrelated to simple refractive error is twice as prevalent among blacks as among whites, although the difference narrows among the elderly. The reasons for this race- and age-related pattern are uncertain. METHODS AND RESULTS: A randomly selected, stratified, multistage cluster sample of 2395 blacks and 2913 whites 40 years of age and older in East Baltimore underwent detailed ophthalmic examinations by a single team. We identified 64 subjects who were blind in both eyes. The leading causes of blindness were unoperated senile cataract (accounting for blindness in 27 of the total of 128 eyes), primary open-angle glaucoma (17 eyes), and age-related macular degeneration (16 eyes). Together, these three disorders accounted for 47 percent of all blindness in this sample. Unoperated cataract accounted for 27 percent of all blindness among blacks, among whom it was four times more common than among whites; whites were almost 50 percent more likely than blacks to have undergone cataract extraction before the age of 80 (P less than 0.002). Primary open-angle glaucoma accounted for 19 percent of all blindness among blacks; it was six times as frequent among blacks as among whites and began 10 years earlier, on average. By contrast, age-related macular degeneration resulting in blindness was limited to whites, among whom it was the leading cause of blindness (prevalence, 2.7 per 1000; 95 percent confidence interval, 1.2 to 5.4); it affected 3 percent of all white subjects 80 years of age or older. CONCLUSIONS: The pattern of blindness in urban Baltimore appears to be different among blacks and whites. Whites are far more likely to have age-related macular degeneration, and blacks to have primary open-angle glaucoma. The high rate of unoperated cataracts among younger blacks and among elderly subjects of both races suggests that health services are underused. Half of all blindness in this urban population is probably preventable or reversible.

Adult↗
PubMed1991

Purification and characterization of human recombinant insulin-like growth factor binding protein 3 expressed in Chinese hamster ovary cells.

Recombinant human insulin-like growth factor binding protein 3 (hIGFBP-3) stably expressed in chinese hamster ovary cells (CHO cells) has been purified to homogeneity from serum-free culture media. The purified protein migrates as a doublet (45/43 kDa) upon SDS-PAGE. The purified recombinant hIGFBP-3 is fully active and binds one mole of IGF-I per mole of recombinant binding protein. When the transfected CHO cells are treated with tunicamycin a single 29 kDa hIGFBP-3 protein is observed. This expressed hIGFBP-3 protein maintains its ability to bind IGF-I. N-Glycanase treatment of the purified hIGFBP-3 protein results in a protein that migrates similar to E. coli-derived IGFBP-3 upon SDS-PAGE under reducing conditions (30 kDa). Carboxymethylation of hIGFBP-3 suggests that all 18 cysteines are involved in disulfide linkages. These results represent the first purification and characterization of recombinant hIGFBP-3 expressed in CHO cells.

Animals↗
PubMed1991

Racial variations in the prevalence of primary open-angle glaucoma. The Baltimore Eye Survey.

OBJECTIVE: --To compare the prevalence of primary open-angle glaucoma between black and white Americans. DESIGN, SETTING, AND PARTICIPANTS: --The design was a population-based prevalence survey of a noninstitutionalized black and white population aged 40 years or older from the eastern and southeastern health districts of Baltimore, Md. A multistage random sampling strategy was used to identify 7104 eligible participants, of whom 5308 (2395 blacks, 2913 whites) received an ophthalmologic screening examination. Those with abnormalities were referred for definitive diagnostic evaluation. MAIN OUTCOME MEASURE: --Primary open-angle glaucoma was defined based on evidence of glaucomatous optic nerve damage, including abnormal visual fields and/or severe optic disc cupping, and was independent of intraocular pressure. MAIN RESULTS: --Age-adjusted prevalence rates for primary open-angle glaucoma were four to five times higher in blacks as compared with whites. Rates among blacks ranged from 1.23% in those aged 40 through 49 years to 11.26% in those 80 years or older, whereas rates for whites ranged from 0.92% to 2.16%, respectively. There was no difference in rates of primary open-angle glaucoma between men and women for either blacks or whites in this population. Based on these data, an estimated 1.6 million persons aged 40 years or older in the United States have primary open-angle glaucoma. CONCLUSIONS: --Black Americans are at higher risk of primary open-angle glaucoma than their white neighbors. This may reflect an underlying genetic susceptibility to this disease and indicates that additional efforts are needed to identify and treat this sight-threatening disorder in high-risk communities.

Adult↗
PubMed1991

Efficacy of vitamin A in reducing preschool child mortality in Nepal.

Community trials of the efficacy of vitamin A supplementation in reducing preschool childhood mortality have produced conflicting results. To resolve the question, a randomised, double-masked, placebo-controlled community trial of 28,630 children aged 6-72 months was carried out in rural Nepal, an area representative of the Gangetic flood plain of South Asia. Randomisation was carried out by administrative ward; the vitamin-A-supplemented children received 60,000 retinol equivalents every 4 months and placebo-treated children received identical capsules containing 300 retinol equivalents. After 12 months, the relative risk of death in the vitamin-A-supplemented compared with the control group was 0.70 (95% confidence interval 0.56-0.88), equivalent to a 30% reduction in mortality. The trial, which had been planned to last 2 years, was discontinued. The reduction in mortality was present in both sexes (relative risk for boys 0.77; for girls 0.65), at all ages (range of relative risks 0.83-0.50), and throughout the year (0.76-0.67). The reduction in mortality risk was not affected by acute nutritional status, as measured by arm circumference. Thus, periodic vitamin A delivery in the community can greatly reduce child mortality in developing countries.

Adult↗
PubMed1991

Cloning and characterization of bovine insulin-like growth factor binding protein-3 (bIGFBP-3).

We report for the first time the isolation of a cDNA encoding the complete amino acid sequence for bovine growth hormone-dependent insulin-like growth factor binding protein-3 (bIGFBP-3). The deduced amino acid sequence from the cDNA revealed a mature polypeptide consisting of 264 amino acids and a 27 amino acid putative signal peptide. The amino acid sequence is over 80% homologous with human IGFBP-3 with complete conservation of the 18 cysteine residues and the 3 Asn-linked glycosylation sites. Between the two species there are 44 amino acid substitutions. Northern analysis of the bIGFBP-3 mRNA in bovine tissue revealed a single mRNA species of 1.65 kilobases.

Amino Acid Sequence↗
PubMed1991

Congenital myopathy with oculo-facial abnormalities (Marden-Walker syndrome).

Marden-Walker syndrome present in the neonatal period is characterized by oculo-facial abnormalities, congenital myopathy, and contractures. A newborn infant with a similar pattern of anomalies is reported, and further evidence for autosomal recessive inheritance as well as new neuropathological findings are included.

Contracture↗
PubMed1991

Clinically detectable nerve fiber atrophy precedes the onset of glaucomatous field loss.

Standardized perimetry and nerve fiber layer and color fundus photography were performed annually on 1344 eyes with elevated intraocular pressures. In 83 eyes, glaucomatous field defects developed that met rigid criteria on manual kinetic and suprathreshold static perimetry. Individual nerve fiber layer photographs were read by two masked observers. The more sensitive of the two identified nerve fiber layer defects in 88% of readable photographs at the time field loss first occurred; 60% (6/10) of eyes already had nerve fiber layer defects 6 years before field loss. In contrast, the nerve fiber layer was considered abnormal in only 11% (3/27) of normal eyes and 26% (84/327) of hypertensive eyes. The location of nerve fiber layer and field defects closely corresponded, but nerve fiber layer loss was generally more widespread. Examiner experience and severity of optic nerve damage influenced results. Mild focal defects were more readily recognized than more severe diffuse atrophy. Nerve fiber layer defects expanded with time, often by the development and coalescence of adjacent areas of damage.

Adult↗
PubMed1991

Socioeconomic status and visual impairment among urban Americans. Baltimore Eye Survey Research Group.

The Baltimore Eye Survey is a population-based study of ocular disorders conducted in East Baltimore, Md, designed to determine the prevalence and severity of vision loss and ocular disease and their relationships to socioeconomic and other risk factors. This survey comprised 5300 subjects (2911 whites and 2389 blacks). Visual impairment was associated with age, race, general health status, educational level, income, and employment status. An identified association of race with blindness and visual impairment was reduced, but not eliminated, after adjustment for these socioeconomic factors, indicating that socioeconomic status itself is an important determinant of visual impairment.

Adult↗
PubMed1991

Risk of cataract and history of severe diarrheal disease in southern India.

A case-control study was carried out in the state of Tamil Nadu, southern India, to examine the association between the risk of visually disabling cataract and a lifetime history of severe diarrhea (including cholera). A series of 421 subjects, aged 35 to 65 years, meeting case (n = 181) and control (n = 240) eligibility criteria were enrolled from 19 rural cataract-screening camps. Ninety case-control pairs were postmatched for (reported) age (+/- 2 years), sex, and area of residence. A history of diarrhea was obtained by using an algorithm developed by other investigators in India who have reported a strong association between cataract and diarrhea. An odds ratio of 0.8 (95% confidence limits: 0.0, 3.2) was obtained from matched pairs analysis, and an odds ratio of 1.3 (95% confidence limit: 0.6, 2.7) was obtained among all subjects (n = 392) from a logistic analysis that adjusted for age, sex, occupation, area of residence, and caste. Findings of this study do not support the hypothesis of an increased risk of visually disabling cataract in persons with a positive history of severe diarrhea.

Adult↗
PubMed1991

National outcomes of cataract extraction. Endophthalmitis following inpatient surgery.

We analyzed the likelihood of rehospitalization for endophthalmitis in 338,141 Medicare beneficiaries over age 65 years who were admitted to US hospitals for cataract extraction in 1984. This cohort represents approximately one half of all persons who underwent cataract extraction under the Medicare program in 1984. Extracapsular extraction was performed in 195,587 (58%) of cases, intracapsular cataract extraction in 99,971 (30%), and phacoemulsification in 28,474 (8%). The risk of rehospitalization for endophthalmitis in the year following surgery was 0.17% for intracapsular cataract extraction compared with 0.12% for extracapsular extraction or phacoemulsification (P less than .002). The risk of endophthalmitis at 1 month was higher for intracapsular cataract extraction than for extracapsular extraction or phacoemulsification (0.11% vs 0.085%), although the difference did not reach statistical significance. Cataract surgery accompanied by anterior vitrectomy increased the 1-month risk of rehospitalization for endophthalmitis to 0.41%, more than a four-fold increase over that for cataract surgery alone (0.09%; P less than .05). The rates of endophthalmitis at 1 year were 0.58% and 0.13%, respectively, for cataract surgery with anterior vitrectomy and cataract surgery alone (P less than .0001). No significant differences in the rate of rehospitalization for endophthalmitis were observed based on the use of an intraocular lens, age, or race. Endophthalmitis within 1 year of surgery was 1.2 times more frequent in men than in women (0.16% vs 0.13%; P = .03). Overall, the likelihood of postoperative endophthalmitis from a national sample is consistent with case series previously reported.

Actuarial Analysis↗
PubMed1991

Relationship between intraocular pressure and primary open angle glaucoma among white and black Americans. The Baltimore Eye Survey.

A detailed ocular examination, including perimetry, was conducted on 5308 black and white subjects aged 40 years and older in a population-based prevalence survey in east Baltimore, Md. Repeated, detailed examinations were carried out on selected subjects. Roughly half of all subjects with optic nerve damage from primary open angle glaucoma, regardless of race, were unaware that they had the condition. The average intraocular pressure (IOP) among black patients with glaucoma who were receiving treatment was virtually identical to that in those black patients who were not receiving treatment (median IOP, 20 mm Hg); treated eyes of white patients had a lower IOP than those eyes of white patients who were not receiving treatment (mean [+/- SD] IOP, 18.69 +/- 3.23 mm Hg vs 24.15 +/- 5.23 mm Hg; P less than .001). The risk of glaucomatous optic nerve damage increased with the height of the screening IOP, particularly at levels of 22 to 29 and 30 mm Hg and above (relative rate compared with IOP of 15 mm Hg or lower, 12.8 and 40.1 mm Hg, respectively). More than half of all glaucomatous eyes had a screening IOP below 21 mm Hg, whether these eyes were receiving treatment or not. The IOP in glaucomatous eyes tended to rise on follow-up, in contrast with nonglaucomatous eyes in which the IOP was as likely to rise as to fall. Results confirmed that IOP is an important factor in glaucoma, but did not support the traditional distinction between "normal" and "elevated" pressure, nor its corollaries, "low-tension" glaucoma and "high-tension" glaucoma.

Black People↗
PubMed1991

Comparison of analytic algorithms for detecting glaucomatous visual field loss.

The sensitivity and specificity of alternate analytic strategies for recognizing glaucomatous visual field loss from automated threshold perimetry (C-30-2 test of the Humphrey Field Analyzer) were compared among one eye each of 106 patients with glaucoma and 249 normal subjects. Algorithms included commercially available global indexes and cross-meridional differences (Statpac 1 and Statpac 2), as well as cross-meridional and cluster analyses that were developed independently for natural history studies and clinical trials. The sensitivity of most algorithms was high, except for those that used only diffuse loss as an indicator of abnormality. Specificity was acceptably high for all algorithms. Subjects who failed to meet the manufacturer's standard for reliability had much reduced specificity, but sensitivity was also affected. Algorithms that were based on any of the alternate definitions of localized reduction in retinal sensitivity performed equally well, which suggests that any of these approaches is useful in searching for glaucomatous visual loss as typified by this database. Availability, familiarity, and convenience may govern the selection of any one analytic approach for use in a particular setting.

Algorithms↗
PubMed1991

Biologically active synthetic fragments of human basic fibroblast growth factor (bFGF): identification of two Asp-Gly-Arg-containing domains involved in the mitogenic activity of bFGF in endothelial cells.

Synthetic peptides derived from the amino acid sequence of human basic fibroblast growth factor (bFGF) have been assayed for the capacity to exert bFGF agonist and antagonist activities in cultured endothelial cells. bFGF fragments A and C, which correspond to the sequences bFGF (38-61) and bFGF (82-101), induce a limited but statistically significant increase in cell number when administered to cultures of fetal bovine aortic endothelial GM 7373 cells and adult bovine aortic endothelial cells. The two peptides also exert a partial antagonist activity when GM 7373 cells are stimulated to proliferate by bFGF, but they do not affect cell proliferation induced by serum, epidermal growth factor (EGF), phorbol ester (TPA), or 1,2-diacylglycerol (diC8). Moreover, antibodies raised against peptides A and C specifically quench the mitogenic activity of bFGF. Peptides A and C contain the amino acid sequence Asp-Gly-Arg (DGR), which is the inverse of the cell adhesion signal sequence RGD recognized by integrins. DGR- and RGD-containing tetra- and heptapeptides inhibit the mitogenic activity exerted by bFGF and by the two active bFGF fragments. They do not affect cell proliferation induced by acidic FGF, EGF, serum, TPA, and diC8. However, neither peptides A and C, their corresponding antibodies, nor DGR-and RGD-containing peptides inhibit the binding of 125I-bFGF to its low and high affinity binding sites. The data suggest that amino acid residues 38-61 and 82-101, both containing a core DGR sequence, represent two "activation" domains of bFGF. Both domains are involved in the modulation of the mitogenic activity of bFGF without interacting directly with the bFGF receptor.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗