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Biomedical subjects

M Lloyd

Publications and source records attributed to M Lloyd.

At least 73 records · Page 4Linked to original sources
PubMed1991

Smoking during pregnancy and its effects on child cognitive ability from the ages of 8 to 12 years.

Maternal smoking during pregnancy and subsequent child cognitive development and ability were examined in a birth cohort of New Zealand children studied to the age of 12 years. Analysis at a bivariate level showed that children whose mothers smoked during pregnancy scored significantly lower on standardised tests of intelligence, reading and mathematical ability than children whose mothers did not smoke. However, after adjustment for confounding covariates, the results showed no detectable relationship between smoking during pregnancy and child cognitive ability. These results suggest that children whose mothers smoked during pregnancy fared worse on tests of cognitive ability not because of possible causal effects of smoking, but rather because these children tended to come from families which provided a relatively disadvantaged home environment.

Child↗
PubMed1991

Confirmatory factor models of attention deficit and conduct disorder.

The paper presents four alternative confirmatory factor models to represent the structure of measures of attention deficit and conduct disorder obtained from multiple sources. These models range in complexity from a simple one-factor model with no method effects to a two-factor model with method effects. These models were fitted to data gathered on maternal, teacher and self-report of attention deficit and conduct disorder for a sample of New Zealand children studied at ages 9 and 10 years. The analysis strongly suggests that the best representation of the data was a two-factor model in which there were distinct factors of attention deficit and conduct disorder with these factors being highly correlated (r = 0.87-0.88). It is suggested that the most suitable clinical nomenclature may be to describe conduct disorder and attention deficit generically as externalizing disorders, subscripting this classification with clauses which describe the relative contributions of conduct disorder and attention deficit. The implications of this finding for the measurement, classification and explanation of conduct disorder and attention deficit disorder are discussed.

Attention Deficit Disorder with Hyperactivity↗
PubMed1991

Characteristics of physicians with obstetric malpractice claims experience.

This study compared the demographic and practice characteristics of physicians with and without obstetric malpractice experience. The sample consisted of 387 family physicians and 204 obstetricians in Washington state who were insured for obstetrics by a major malpractice carrier between January 1982 and June 1988. Fifty-three physicians (9%) had an obstetric malpractice claim during the study period. The approximate overall rate of obstetric malpractice claims was low: 0.32 per 1000 deliveries. The higher the total delivery volume (exposure), the greater the chance of having malpractice experience. Although physicians with practices of over 200 deliveries per year were more likely to have had malpractice experience, their risk of malpractice experience per delivery was lower than that of providers doing fewer than 200 deliveries per year. Our work suggests that insurers might consider basing obstetric malpractice premiums on numbers of deliveries rather than specialty.

Female↗
PubMed1990

The biosynthetic basis of adult lactase deficiency.

The intestinal brush-border enzyme lactase splits lactose into its component monosaccharides, glucose and galactose. Relative deficiency of the enzyme during adulthood is a common condition worldwide and is frequently associated with symptoms of lactose intolerance. We studied the synthesis and processing of lactase in normal and adult hypolactasic subjects using human intestinal explants in organ culture. Metabolic labeling experiments in our control subjects with [35S]methionine followed by immunoprecipitation, sodium dodecyl sulfate-polyacrylamide-gel electrophoresis, and fluorography demonstrated that newly synthesized lactase is initially recognized as a precursor molecule with a relative molecular weight (Mr) of 205,000. Over the course of several hours most of the labeled lactase was converted to a mature form of 150,000 Mr. Transiently appearing forms of 215,000 and 190,000 Mr were identified and were felt to represent intermediary species generated during intracellular processing. We identified two distinct alterations in lactase biosynthesis accounting for adult hypolactasia. Studies in three deficient subjects demonstrated markedly reduced synthesis of the precursor protein though posttranslational processing appeared identical to normal. Multiple studies in a fourth deficient subject demonstrated synthesis of ample amounts of precursor lactase but reduced conversion to the mature active form of the enzyme.

Adult↗
PubMed1990

Why do physicians stop practicing obstetrics? The impact of malpractice claims.

We studied all physicians who purchased obstetric malpractice insurance from the Washington State Physicians Insurance Exchange and Association between January 1, 1982 and July 1, 1988. Of the 690 physicians studied, 171 (32% of the family physicians and 10% of the obstetricians) discontinued obstetrics but remained in practice. Physicians who discontinued obstetric practice were older, more likely to practice in an urban area, and more likely to be in solo practice than those who did not. Obstetricians who discontinued obstetric practice had a higher rate of new obstetric malpractice claims than did those who did not quit practicing obstetrics--14.5 versus 6.2 claims per 100 physician-years of coverage. By contrast, those family physicians leaving obstetrics had a lower rate of new claims than their peers who did not quit. We conclude that older physicians--particularly those in urban and solo practice--are most likely to stop practicing obstetrics, regardless of specialty. In addition, being named as the target of an obstetric malpractice claim plays a significant role in the decision of some obstetricians to discontinue obstetric practice.

Attitude of Health Personnel↗
PubMed1988

Synthesis and intracellular processing of aminooligopeptidase by human intestine.

Aminooligopeptidase is an intrinsic glycoprotein of the brush border membrane important for hydrolysis of the oligopeptide products of intraluminal protein digestion. To study its synthesis and intracellular processing, we performed pulse-chase experiments using [35S]methionine to label proteins of cultured human intestinal explants obtained by endoscopic biopsy. Aminooligopeptidase was isolated by immune precipitation with a monoclonal antibody and its molecular size was assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorography. A precursor of relative molecular weight (Mr) 127,000 appeared within 10 min of chase and appeared to begin conversion to an Mr 150,000 form (the size of brush border membrane aminooligopeptidase) within 60 min. To determine if the change in molecular size was the consequence of alterations in glycosylation, we studied the susceptibility of the two forms to endo-beta-N-acetylglucosaminidase H, which cleaves immature high-mannose N-linked carbohydrate chains, and to peptide: N4-(N-acetyl-beta-glucosaminyl)asparagine amidase, which cleaves both the high-mannose and complex N-linked carbohydrate chains. Only the early Mr 127,000 aminooligopeptidase was sensitive to endo-beta-N-acetylglucosaminidase H, suggesting that the larger form results from trimming of high-mannose cores and adding terminal sugars in the Golgi complex. Both forms were sensitive to peptide: N4-(N-acetyl-beta-glucosaminyl)asparagine amidase, generating an Mr 114,000 species. The kinetics of the synthesis and processing of aminooligopeptidase and sucrase-isomaltase were compared by immunoprecipitation of both proteins from the same tissue after separating the microvillous membrane from the remainder of the cellular membranes. Labeled aminooligopeptidase was present intracellularly in its mature form within 60 min and was detected exclusively in the brush border membrane by 90 min. Most of the labeled sucrase-isomaltase pool had not yet undergone complex glycosylation during the same period. These data demonstrate that although human intestinal aminooligopeptidase undergoes N-linked glycosylation like sucrase-isomaltase, the synthesis of aminooligopeptidase differs from that of sucrase-isomaltase in respect to the absence of a high-molecular-weight precursor and more rapid pre-Golgi processing.

Aminopeptidases↗
PubMed1987

Painful bone end sclerosis. Variant of renal osteodystrophy simulating osteonecrosis.

Painless sclerotic change in bone ends occurring as a manifestation of renal osteodystrophy has been reported in two previous cases. The sclerotic change can, however, be accompanied by nonspecific periarticular pain. Radiologic changes in "bone ends" may mimic osteonecrosis. Nuclear bone scanning may show increased radionuclide uptake early in both conditions but late uptake may be less in "bone end sclerosis." The "rugger jersey" spine occurring in the usual osteosclerosis of renal osteodystrophy has been consistently absent in this variant. Osteonecrosis should be excluded in making the diagnosis of "bone end sclerosis."

Adult↗
PubMed1982

Exercise after myocardial infarction: a controlled trial.

Six weeks after acute myocardial infarction, 303 men were randomly divided into exercise and control groups. The exercise group attended the hospital gymnasium twice weekly for a three-month supervised exercise course. Both groups were exercise tested before and after the course and at subsequent follow-up. The exercise group increased their physical fitness greatly compared with the control group. Eight per cent of the exercise group died during the period of follow-up, compared with 14 per cent of the control group; this difference is not significant. There was an apparent improvement in mortality in those with inferior MI who completed the exercise course, which was not seen in those with MI in other sites. For many patients after MI progressive exercise is safe, improves physical fitness and may reduce mortality for those after inferior MI.

Clinical Trials as Topic↗
PubMed1981

How Americans say they drink: preliminary data from two recent national surveys.

Data from two recent National Center for Health Statistics (NCHS) surveys which included alcohol consumption questions are described. These surveys are the Health and Nutrition Examination Survey (HANES I), providing alcohol consumption, dietary recall, health and demographic data for over 20,000 respondents; and the Health Habits Section of the 1977 Health Interview Survey (HIS) which provides responses of 23,000 people on drinking behavior and health factors such as smoking, physical disabilities, and dietary habits. Drinking data from these surveys are limited but of sufficient accuracy to be useful for cross-classification of drinking with health, socio-economic and demographic variables. Drinking patterns correlate reasonably well with those reported in other national surveys. Selected findings show that patterns of drinking and dietary intake are similar at national and regional levels, with the South remaining the region lowest in alcohol consumption levels. Surveys consistently under-report alcohol quantities expected from sales in all regions; potential reasons for this are discussed. Highest consumption is reported by males (3 to 4 times that of females), those with European national origins, those who are working or in school (college) rather than those who are retired or keeping house, and those between 25 and 64 years old. Beer remains the beverage of choice, particularly among those who are the heaviest drinkers. The potential for future analyses of drinking behavior and its health implications is explored, and areas for further investigation are suggested. Data preparations have been completed so that information on alcohol consumption can be more readily related to medical history, medical examination, laboratory findings, disability, and health care data in these surveys.

Adolescent↗
PubMed1977

Maintenance of the ratio of alpha and beta globin synthesis in rabbit reticulocytes.

The synthesis of rabbit alpha and beta globins under various conditions was studied using intact reticulocytes and reticulocyte cell-free systems. Raising salt concentration of media in which reticulocytes were incubated with radioactive amino acids reduced the total protein synthesis but did not affect the ratio of alpha to beta globins produced. Using a reticulocyte lysate which had been incubated with micrococcal nuclease to remove the endogenous globin messenger RNA activity, it was found that unlike the intact cell or the untreated lysate very little alpha globin was synthesised on adding purified globin mRNA. These results are discussed in terms of their compatibility with some proposed models of coordination of alpha and beta globin production.

Animals↗