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Biomedical subjects

D J Hunter

Publications and source records attributed to D J Hunter.

At least 289 records · Page 16Linked to original sources
PubMed1989

Precise excision of telomere-bearing transposons during Oxytricha fallax macronuclear development.

In ciliated protozoa, development of the macronucleus from a copy of the germ line micronucleus involves elimination of a large number of sequences by DNA splicing akin to precise excision of transposons. The known examples of such internal eliminated sequences (IESs) are not repetitive. The telomere-bearing elements (TBE1s) of Oxytricha fallax are a family of transposons. We show that two particular TBE1s are also IESs. TBE1-1 and TBE1-2 disrupt a micronuclear region that codes for macronuclear DNA. A variety of tests indicates that each TBE1 and one copy of the flanking target repeat is absent from most, if not all, molecules of the macronuclear DNA, as if the TBE1s were precisely excised during macronuclear development. Three alternative explanations for the absence of TBE1-1 and TBE1-2 from the macronuclear DNA were tested. First, because two other highly homologous versions of that DNA are also found in the macronucleus, recombination between versions during or after macronuclear development could have bypassed the elements. Recombination in the regions flanking the elements was not detected. Second, micronuclear DNA blots show no evidence of a micronuclear counterpart of the macronuclear region that lacks TBE1-1. Third, TBE1-2 was demonstrated in two sexually independent cell lines. This shows that it pre-existed in the germ line, as opposed to having transposed into the micronuclear DNA subsequent to the generation of the macronucleus of the vegetative line that is usually studied. We conclude that TBE1-1 and TBE1-2, and possibly many of the other approximately 1900 micronucleus-limited TBE1s are excised as IESs during macronuclear development. These transposons appear to enjoy the luxury of relaxed constraints on family expansion, because they are removed from the genome before it is expressed. We discuss the possibility that all IESs are transposon-derived, that all are excised by transposition machinery, and that linear excision products are early intermediates in transposition.

Animals↗
PubMed1989

General management and medical autonomy in the National Health Service.

Clinical freedom is an elastic concept and its practical meaning to clinicians varies with time and context. Management pressure on clinical freedom is also likely to be elastic. Resource constraints are increasing pressure on clinical freedom. The paper reviews the nature of such pressure and considers the extent to which general managers have successfully eroded medical autonomy. Drawing on emerging evidence from research in progress on the impact of general management, the paper concludes that there is little sign of change in doctor-manager relations. They continue to inhabit a shared culture of medical autonomy in which only rarely do managers challenge clinicians.

Decision Making↗
PubMed1989

Mortality and hospital morbidity from cirrhosis of the liver in relation to per capita consumption of absolute alcohol, education and native status, Ontario; 1978 to 1982.

Correlation and regression analyses have been carried out to test the hypothesis that areas experiencing high per capita consumption of absolute alcohol will also experience correspondingly higher annual rates of cirrhosis, in Ontario from 1978 to 1982. Adjustment was made for the influence of socio-demographic variables upon hospital morbidity and mortality rates. Areas experiencing higher per capita consumption of absolute alcohol were found to have higher hospital morbidity. The relationship between hospital morbidity and general mortality from cirrhosis, and per capita consumption of absolute alcohol appears to be growing weaker; no relationship could be demonstrated, however, between cirrhosis mortality and hospital morbidity and proportionate native population and education status.

Adult↗
PubMed1988

Fetal renal failure associated with intrauterine growth retardation.

Four preterm infants with severe intrauterine growth retardation had renal failure from birth. The amount of asphyxia associated with the birth process did not fully explain the renal failure. Before delivery all for fetuses had severe oligohydramnios and an empty urinary bladder. These observations strengthen the view that severe intrauterine growth retardation may be accompanied by oligohydramnios caused by fetal renal failure.

Acute Kidney Injury↗
PubMed1988

Variability in portion sizes of commonly consumed foods among a population of women in the United States.

The use of food frequency questionnaires for measuring dietary intake has become widespread in epidemiologic studies. It has been suggested that inquiring about a person's usual serving size of each food, in addition to the frequency of consumption, will improve the accuracy of this method. This approach implies that individuals characteristically eat a specific amount of any particular food, and that this amount can be reported with reasonable accuracy. To investigate the variability of portion sizes, the authors analyzed data for 68 commonly consumed foods, based on four one-week weighed diet histories recorded by 194 Boston-area women aged 34-59 years during 1980 and 1981. For each food, total population variance in portion size was partitioned into within-person (intraindividual) and between-person (interindividual) components. For all but seven food items (yogurt, liver, mixed vegetables, watermelon, pancakes/waffles, cold cereal, and cooked cereal) the within-person variance in portion size exceeded the between-person variance. The mean of the within-person to between-person variance ratios, after exclusion of two outlying foods, was 3.4 for untransformed portion sizes, and 3.2 after portion sizes were loge-transformed. Foods with a high within-person variance also tended to have a high between-person variance. The dominance of within-person variance in portion sizes suggests that the concept of usual portion size is complex, and that subjects may experience substantial difficulty in specifying their "usual" portion size. The smaller contribution of between-person variance to the total variance in portion size suggests that specification of a standard portion size by the investigator may not introduce a large error in the estimation of food and nutrient intake.

Adult↗
PubMed1988

The diagnosis of acute fatty liver of pregnancy by computed tomography.

We describe 2 patients with biopsy-proven acute fatty liver of pregnancy in whom the diagnosis was suggested by the finding of uniform reduced attenuation values on computed tomography (CT) of the liver. The attenuation values returned to normal with resolution of signs and symptoms following delivery. CT of the liver provides a useful method for the diagnosis of acute fatty liver of pregnancy.

Acute Disease↗
PubMed1987

Diurnal variation in the excretion of 6 beta-hydroxycortisol and estriol at 32 weeks gestation.

We have previously shown a marked diurnal variation in the excretion of cortisol and 6 beta-hydroxycortisol at 36-38 weeks pregnancy with no variation in estrogen excretion. Since others have shown a reciprocal relationship between plasma levels of estriol and cortisol at 30-35 weeks of pregnancy, we decided to determine whether a similar relationship was present in urinary concentrations of cortisol, 6 beta-hydroxycortisol and estriol at this gestational age. A significant variation in excretion of both cortisol and 6 beta-hydroxycortisol was found. The variation in urinary levels of estriol was less than that of the corticosteroids but followed the same pattern.

Circadian Rhythm↗
PubMed1987

A prospective study investigating the mechanism of thrombocytopenia in preeclampsia.

Hemostatic and platelet function studies were performed prospectively on 61 preeclamptic patients and 24 healthy pregnant control patients to delineate possible causes of thrombocytopenia in preeclampsia. Thrombocytopenia occurred in 50% of the preeclamptic patients, and was accompanied by qualitative platelet defects as shown by an increased bleeding time and decreased biosynthesis of thromboxane A2. All patients had normal routine coagulation and protamine sulphate paracoagulation assays. All nulliparous patients had normal levels of fibrinopeptide A, but approximately 60% of parous patients had slight elevations of fibrinopeptide A. Elevated levels of platelet-associated immunoglobulin G (IgG) were demonstrated in 35% of all preeclamptic patients and were inversely correlated (r = -0.524) with the severity of the thrombocytopenia. This study indicates that, at least in nulliparous patients, thrombin action is not a major contributor to the development of thrombocytopenia in preeclampsia. The observation of elevated levels of platelet-associated IgG suggests that immune mechanisms could contribute to the thrombocytopenia in some patients.

Adult↗
PubMed1987

Rural-urban variations in service provision for elderly people.

Findings reported from a survey of 997 people aged 75 years and over living at home in a rural and an urban area showed that the two areas were similar in overall levels of support and in levels of perceived need. The rural area enjoyed rather more generous support from district nurses and health visitors than the urban area, a finding which challenges the widely-held view that rural areas suffer from lower levels of support and have higher levels of felt need. The few differences between the areas that did emerge were not necessarily a consequence of location; other explanations may be found in the operating styles of the services, and in the amount and type of informal support to be found in the two areas. Overall, the findings question the validity of a simple rural-urban dichotomy in studies of elderly people.

Aged↗
PubMed1986

The quick-mount pipeline connector: failure of a "fail-safe" device.

This report describes the absence of gas flow despite the apparent proper mounting of a Canadian Liquid Air nitrous oxide quick-mount connector to its wall outlet. A similar but potentially more dangerous malfunction can occur with oxygen quick-mount connectors. The nature and cause of this defect are examined.

Anesthesiology↗