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Biomedical subjects

A Sommer

Publications and source records attributed to A Sommer.

At least 19 recordsLinked to original sources
PubMed1992

Organization of phosphatidylcholine and sphingomyelin in the surface monolayer of low density lipoprotein and lipoprotein(a) as determined by time-resolved fluorometry.

Fluorescent analogs of phosphatidylcholine (PC) and sphingomyelin (SM) labeled with diphenylhexatrienylpropionic acid (DPH) were prepared and incorporated into the surface layer of human low density lipoprotein (LDL) and lipoprotein(a) (Lp(a)). Fluorescence anisotropy measurements of DPH-PC and DPH-SM in both lipoprotein classes were carried out at different temperatures ranging from 20 to 37 degrees C. DPH-PC as well as DPH-SM were shown to reside in more rigid domains in Lp(a) than in LDL according to higher anisotropy values in Lp(a). In both LDL and Lp(a), DPH-PC experienced a more rigid environment than DPH-SM, suggesting different environments of PC and SM in the surface shell of the lipoproteins. Fluorescence lifetimes of the labeled lipoproteins were determined by phase and modulation fluorometry. We found bimodal Lorentzian distributions for the decay times of DPH-PC and DPH-SM in LDL and Lp(a). Lifetime distribution centers for labeled lipids were very similar except for DPH-PC in Lp(a) which was shifted to longer lifetimes, suggesting a less polar environment of PC in Lp(a) than in LDL. The distributional width of DPH-PC in Lp(a) was broader than in LDL. Accordingly, phosphatidylcholine must be localized in a more homogeneous environment in LDL as compared with Lp(a). On the other hand, no difference in distributional widths was observed for DPH-SM in both lipoproteins, showing that SM organization in Lp(a) is unaffected by apo(a). From the obtained fluorescence data we propose that apoproteins discriminate between the choline phospholipids and preferentially associate with phosphatidylcholine. This effect is enhanced in Lp(a) due to the presence of apolipoprotein(a).

Fluorescence Polarization↗
PubMed1992

Autosomal dominant inheritance of tetramelic monodactyly.

We report on tetramelic monodactyly with autosomal dominant inheritance. The propositus and all affected relatives had only digital malformations as determined by physical examination or history. Since it could not be determined that the involved digits of the propositus or relatives were fifth fingers and toes, we conclude this to be the first report of this type of hand and foot malformation with autosomal dominant inheritance.

Adult↗
PubMed1992

National outcomes of cataract extraction. Increased risk of retinal complications associated with Nd:YAG laser capsulotomy. The Cataract Patient Outcomes Research Team.

PURPOSE: The authors studied 57,103 randomly selected Medicare beneficiaries who underwent extracapsular cataract extraction in 1986 or 1987 to determine the possible association between performance of neodymium (Nd):YAG laser capsulotomy and the risk of subsequent retinal break or detachment. METHODS: Cases of cataract surgery were identified from Medicare claims submitted in 1986 and 1987 and were followed through the end of 1988. Episodes of cataract surgery, posterior capsulotomy, and retinal complications were ascertained based on procedure and diagnosis codes listed in physician bills and hospital discharge records. Lifetable and Cox's proportional hazards models were used to analyze the risk of retinal detachment or break in patients undergoing and not undergoing capsulotomy during the period of observation. RESULTS: Of the 57,103 persons identified as having undergone extracapsular cataract extraction in 1986 or 1987, 13,709 subsequently underwent Nd:YAG laser capsulotomy between 1986 and 1988. A total of 337 persons had aphakic or pseudophakic retinal detachments between 1986 and 1988 and an additional 194 underwent repair of a retinal break. Proportional hazards modeling shows a 3.9-fold increase in the risk of retinal break or detachment among those who underwent capsulotomy (95% confidence interval: 2.89 to 5.25). Younger patient age, male sex, and white race also were associated with increased risk of retinal complications after extracapsular cataract extraction. CONCLUSION: The authors conclude that there is a statistically significant increase in the risk of retinal detachment or break in those patients who undergo capsulotomy after cataract extraction. Therefore, capsulotomy should be deferred until the patient's impairment caused by capsular opacification warrants the increased risk of retinal complications associated with performance of capsulotomy.

Aged↗
PubMed1992

An evaluation of optic disc and nerve fiber layer examinations in monitoring progression of early glaucoma damage.

From annual examinations of 813 ocular hypertensive eyes, the authors compared optic disc and nerve fiber layer photographs in 2 age-matched subgroups: 37 eyes that converted to abnormal visual field tests at the end of a 5-year period and 37 control eyes that retained normal field tests. Disc change was detected in only 7 of 37 (19%) converters to field loss and in 1 of 37 (3%) controls. Progressive nerve fiber layer atrophy was observed in 18 of 37 (49%) converters and in 3 of 37 (8%) controls. Serial nerve fiber layer examination was more sensitive than color disc evaluation in the detection of progressive glaucoma damage at this early stage of glaucoma. The evaluation of cup-to-disc ratio or of the nerve fiber layer appearance in the initial photograph taken 5 years before field loss were equally predictive of future field damage. The position of nerve fiber layer defects was highly correlated with the location of subsequent visual field loss.

Aged↗
PubMed1992

Maternal but not paternal transmission of 15q11-13-linked nondeletion Angelman syndrome leads to phenotypic expression.

Angelman syndrome (AS) may result from either maternally inherited deletions of chromosome 15q11-13 or from paternal uniparental disomy for chromosome 15. This is in contrast to Prader-Willi syndrome (PWS), which is caused by either paternal deletion of this region or maternal disomy for chromosome 15. However, 40% of AS patients inherit an apparently intact copy of chromosome 15 from each parent. We now describe a family in which three sisters have given birth to four AS offspring who have no evidence of deletion or paternal disomy. We show that AS in this family is caused by a mutation in 15q11-13 that results in AS when transmitted from mother to child, but no phenotype when transmitted paternally. These results suggest that the loci responsible for AS and PWS, although closely linked, are distinct.

Angelman Syndrome↗
PubMed1992

[The nitrogen metabolism in the large intestine of ruminants. 8. Metabolism of intracecally infused 15N-urea with a supplement of pectin in heifers].

Three heifers with live weights of 255, 261 and 300 kg were supplied with ileo-caecal re-entrant cannulas, jugular vena catheters and bladder catheters. The ration consisted of 4 kg maize silage and 4 kg wheat straw pellets. In a previous period 50% of the digesta flow was collected over 12 h/d on 5 consecutive days and stored in a deep-freeze. During the main period the re-entrant cannulas were disrupted and the flowing digesta was quantitatively collected. Precollected digesta and pectin were infused into the distal part of cannula hourly for about 30 hours. During the first 24 hours the digesta was also supplemented with 15N-labelled urea. The amount of pectin corresponded to about 10% of digesta dry mater. An analysis of urine, faeces, digesta and blood plasma were carried out. The application of pectin increased the 15N-incorporation in the bacterial protein of faeces from 4.7% (without supplementation in an earlier experiment) to 10.5% of the introduced 15N. The ammonia-fraction of faeces was markedly higher than the bacterial fraction. The 15N-utilization of urea by the microbes of large intestine was lower in the actual trial evident than with supplementation of starch in the anterior experiment. During the pectin administration the amount of urine increased in comparison with earlier experiments and according to the literature to about the 4.5 fold. The amount of passage of 15N at the ileum cannula (recycled 15N) was 3.8% of the 15N intake. It is the same amount as in experiments in which starch was applied.

Animal Feed↗
PubMed1992

Xerophthalmia and growth in preschool Indonesian children.

Approximately 4000 preschool children in West Java, Indonesia, were examined for xerophthalmia and weighed and measured at 3-mo intervals from March 1977 to December 1978. Children recovering from xerophthalmia over a 3-mo interval gained an average of 124 g (95% CI 42-206) more over 3 mo than normal children. Their height gain was similar to normal children's. Children who developed xerophthalmia during a 3-mo period gained 199 g (95% CI 114-313) less and grew 0.28 cm (95% CI 0.12, 0.44) less than their normal peers. Children with chronic xerophthalmia gained 120 g (95% CI 49-191) less and grew 0.21 cm (95% CI 0.05-0.37) less than normal children. These data suggest that linear and ponderal growth is adversely affected by chronic and incident xerophthalmia, but that catch-up ponderal growth is experienced by children recovering from xerophthalmia.

Body Height↗
PubMed1992

Depressed immune response to tetanus in children with vitamin A deficiency.

A randomized, double-masked, placebo-controlled clinical trial was conducted with 236 preschool children, age 3-6 y, in Indonesia to assess immune status in mild vitamin A deficiency. The immune response to tetanus immunization was used as a measure of immune competence. Clinically normal children (n = 118) and children with mild xerophthalmia (n = 118) were randomly assigned to receive oral vitamin A (60,000 micrograms retinol equivalent) or placebo treatment for a total of four study groups. Two weeks after treatment, children were immunized with diphtheria-pertussis-tetanus vaccine. The immunoglobulin G (IgG) responses to tetanus at baseline and 3 wk following immunization were measured by ELISA. After adjusting for previous tetanus immunization, clinically normal and xerophthalmic children receiving vitamin A had a significantly greater IgG response to tetanus than clinically normal and xerophthalmic children receiving placebo (P less than 0.05). These results suggest that children with mild vitamin A deficiency have a relative immune depression compared with children who have been supplemented to normal vitamin A levels.

Antibody Formation↗
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

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

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

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↗