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Biomedical subjects

M Evans

Publications and source records attributed to M Evans.

At least 487 records · Page 27Linked to original sources
PubMedDate not supplied

Impact of fat reduction on micronutrient density of children's diets: the CATCH Study.

BACKGROUND: The purpose of this study was to examine the impact of fat reduction on vitamin and mineral density in the diets of groups of children who participated in the CATCH school-based intervention study for 2 1/2 years. METHODS: Twenty-four-hour dietary recalls were collected on 1,182 children residing in four states and with diverse ethnic backgrounds, at baseline when they were in third grade and again at follow-up when they were in fifth grade. RESULTS: With a 2.4% reduction in total fat intake from baseline levels in the intervention group, mean changes in vitamin and mineral intakes per 1,000 kcal of this group were small yet significant compared with the control group. As mean fat intake decreased, the nutrient density of most vitamins and minerals increased; the sole exceptions were vitamin E and sodium. Mean intake of all vitamins and minerals studied exceeded 2/3 of the RDA at both baseline and follow- up for both the intervention and the control groups. No significant differences were noted between treatment groups for the percentages of children meeting 2/3 or more of the RDA at both baseline and follow-up periods. CONCLUSIONS: CATCH was successful in maintaining mean vitamin and mineral intakes of intervention group children when total dietary fat was reduced.

Adolescent↗
PubMedDate not supplied

Aortic endothelial mitosis and Evans blue uptake in cholesterol-fed subscorbutic guinea-pigs.

SUMMARY: Groups of ovalbumin sensitised, subscorbutic guinea-pigs were subjected to various regimens for 8-10 weeks. Group 1 were given 0.25 mg/100 g body wt. cholesterol by mouth daily and were stressed with intraperitoneal injections of ovalbumin twice weekly. Group 2 received the cholesterol only and Group 3 were stressed only. Group 4 on the low vitamin C diet only acted as controls. Evans blue uptake tests and tritiated thymidine autoradiographs of Häutchen preparations of aortic endothelium were made on each animal. Endothelial mitosis was greatest in those areas of the aorta that had taken up the Evans blue most avidly. This was most apparent in Group 1, though to a lesser extent in Groups 2 and 3 also. Group 4 showed no dye uptake and the mitotic index was not raised. Blood ascorbic acid and plasma cholesterol levels are given for the various groups.

Animals↗
PubMedDate not supplied

Force-displacement behaviour of biological tissue during distraction osteogenesis.

Limb lengthening and bone transport treatments are used frequently, and complications during treatment are common. Knowledge of the origin of tensile forces which resist distraction and the force-displacement response of biological tissues during extension would assist in reducing complication rates. Two tibial diaphyseal lengthenings carried out using an Ilizarov fixator were monitored by a displacement transducer to determine extension of the lengthening tissue (the regenerate bone), and by force transducers to determine tensile forces in the tissues that resist extension. The position of the force vector within a cross-section of the limb at the regenerate (provided by CT) was used to determine the origin of these forces. The muscle groups and adjacent fascia resisting extension were the gastrocnemius in one subject and the anterior and peroneal compartments in the other. In response to distraction, these tissues had relatively high stiffness (> 200 N/mm), less "immediate" displacement (< 35% of long term non-recoverable displacement) and inconsistent force relaxation properties (0-90%). In contrast, when the force vector was located in the vicinity of the regenerate, tissue exhibited lower stiffness (< 50 N/mm) and more immediate displacement (> 65% of long term nonrecoverable displacement), but also exhibited inconsistent force relaxation (0-67%).

Adaptation, Physiological↗
PubMedDate not supplied

Formation of germ-line chimaeras from embryo-derived teratocarcinoma cell lines.

The recent availability in culture of embryo-derived pluripotential cells which exhibit both a normal karyotype and a high differentiative ability has encouraged us to assess the potential of these cells to form functional germ cells following their incorporation into chimaeric mice. We report here the results of blastocyst injection studies using three independently isolated XY embryo-derived cell lines (EK. CP1 , EK. CC1 .1 and EKCC1 .2) which produce a very high proportion (greater than 50%) of live-born animals that are overtly chimaeric. Seven chimaeric male mice, derived from these three lines, have, so far, proved to be functional germ-line chimaeras.

Animals↗
PubMedDate not supplied

Germ-line transmission of genes introduced into cultured pluripotential cells by retroviral vector.

Embryonic stem cells isolated directly from mouse embryos can be cultured for long periods in vitro and subsequently repopulate the germ line in chimaeric mice. During the culture period these embryonic cells are accessible for experimental genetic manipulation. Here we report the use of retroviral vectors to introduce exogenous DNA sequences into a stem-cell line and show that these modified cells contribute extensively to the somatic and germ-cell lineages in chimaeric mice. Compared with current methods for manipulation of the mouse genome, this approach has the advantage that powerful somatic-cell genetic techniques can be used to modify and to select cells with germ-line potential, allowing the derivation of transgenic strains with pre-determined genetic changes. We have by this means inserted many proviral vector sequences that provide new chromosomal molecular markers for linkage studies in the mouse and that also may cause insertional mutations.

Animals↗
PubMedDate not supplied

Human immunodeficiency virus seroprevalence and risk assessment of a homeless population in Denver.

OBJECTIVE: TO determine the prevalence of human immunodeficiency virus (HIV) infection among the homeless of Denver and to describe behaviors in the homeless that may be associated with HIV infection. DESIGN: A cross-sectional cohort study. METHODS: From July 1990 through June 1994, the authors conducted an unlinked survey collecting demographic and risk exposure data, and from August 1990 through June 1992, a more detailed risk behavior survey was completed on persons who attended the largest homeless clinic in Denver. RESULTS: For the combined survey years, the overall seroprevalence rate in the unlinked survey was 0.9%. Men were more likely to be seropositive than women (1.3% versus 0.1%) (P < 0.001). Black and Hispanic men had higher seroprevalence rates than white men (3.1% and 2.2% versus 0.5%) (P < 0.001). Gay and bisexual men, men who were injection drug users, and men with partners at risk had a nearly fivefold higher seroprevalence rate compared to other risk groups (3.1% versus 0.7%, P < 0.001). During the 4 study years, 14% of homeless persons tested positive for tuberculosis. In the risk behavior survey, 41% of the clients reported previous injection drug use (since 1978), and 22% reported recent use (past 12 months); of this 22%, 16% reported sharing their works (needles and paraphernalia). Seventy percent of the study participants stated that they changed their sexual behavior, and 39% reported using condoms in the past 12 months. CONCLUSIONS: In this homeless Denver population, there is a low seroprevalence of HIV but a high rate of HIV risk behavior. Certain groups of homeless persons are at high risk for HIV infection, and targeted interventions are necessary.

Adult↗
PubMedDate not supplied

Cadaveric study comparing the stability of upper distraction hooks used in Harrington instrumentation.

Many different designs of upper distraction hooks for use in Harrington instrumentation are available. There is no published evidence to date to support the use of one hook in preference to another. This study compares the distraction force required to dislodge the three most commonly used designs of Harrington upper distraction hook. In cadavers the force required for failure of the plain, ribbed, and bifid hooks was compared as were the modest of vertebral fracture at the time of cut out. The bifid hook required a significantly greater distraction force to fracture the lamina, and the pattern of fracture was more extensive than it was with the plain or ribbed hooks.

Aged↗
PubMedDate not supplied

Early changes in the rat hippocampus following seizures induced by bicuculline or L-allylglycine: a light and electron microscope study.

Status epilepticus was induced in thirteen paralysed and ventilated rats by the injection of either bicuculline or L-allylglycine. After 1-2 h of seizure activity the animals were intracardially perfused with a 2% glutaraldehyde/3% paraformaldehyde solution. Hippocampal blocks from each rat were processed for light and electron microscopy. The effects of L-allylglycine were more severe than those of bicuculline. Changes include perivascular and perineuronal swelling of astrocytic processes, and neuronal alterations which were graded as follows: Grade I (least severe), neuronal cytoplasm appears slightly darker than usual; Grade II, condensed or dark neurons, usually with microvacuoles; and Grade III classical 'ischaemic cell change'--the cytoplasm and karyoplasm is dark and shrunken, with or without microvacuoles. Many of the microvacuoles originate from mitochondria. In a few cases swollen and disrupted mitochondria are also seen is distended basal dendrites of the CA3 and CA1 pyramidal neurons. Dentate granule cells appear unaffected. The hippocampal neuronal alterations induced by seizure activity include those of 'ischaemic cell change'. The pathogenetic factors common to hypoxia/ischaemia and status epilepticus remain to be identified.

Allylglycine↗
PubMedDate not supplied

Product names, proper claims? More ethical issues in the marketing of drugs.

OBJECTIVES: To analyse the explicit or implicit claims embodied in the proprietary names of pharmaceutical products. DESIGN: Linguistic and ethical analysis of proprietary names of pharmaceutical products marketed in the UK and in Denmark. RESULTS AND CONCLUSIONS: A number of drugs have names that allude to their indication or actions. Such names may be problematic, however, because they often promise more than the drug can deliver. Taking into account, firstly, the type of allusion and its degree of sophistication, and, secondly, the seriousness of the indication may help in identifying the most problematic drug names.

Denmark↗
PubMedDate not supplied

Bringing support home for families of children with cancer.

The Macmillan paediatric service at Southampton has grown in the context of an established service and in response to the perceived needs of families. In the environment of an internal market, care provided must be more explicit to inform decision making regarding its continuation.

Adolescent↗