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Biomedical subjects

J McLean

Publications and source records attributed to J McLean.

At least 19 recordsLinked to original sources
PubMed1992

Predictors of high risk sexual behaviour in gay and bisexual men.

Evidence of high risk sex between gay men continues to be reported, as does a range of sexual behaviour. Three hundred and sixty-nine homosexually active men from different areas of England were each assessed twice at an an interval of 9 months in order to examine the extent to which a number of social-psychological factors predicted subsequent high risk sexual behaviour. Few of the variables were significantly related to unprotected receptive anal sex in the way that the Health Belief Model predicted, except for some perceptions of costs and benefits of safer sex. However, whether or not men were involved in a regular relationship with a partner was strongly associated with high risk behaviour. The implications of these results are that health education interventions should focus on alerting all men to the social context in which high risk sex is more likely to happen: the regular partnership.

Attitude to Health↗
PubMed1992

Combined treatment with oral etretinate and electron beam therapy in patients with cutaneous T-cell lymphoma (mycosis fungoides and Sézary syndrome).

BACKGROUND: Total skin irradiation for early-stage mycosis fungoides produces clinical remission in 90% of patients, but the median duration of remission is only 2 to 4 years. Etretinate has proven efficacy in advanced mycosis fungoides. Its potential as adjuvant therapy to radiation could be limited by toxicity from the combination. OBJECTIVE: Our purpose was to determine whether oral etretinate at 1 mg/kg can be combined with 35 Gy of radiation without intensifying or prolonging the radiation reaction and to determine the relapse-free survival rate. METHODS: Twenty-three patients began etretinate on day one of radiation and the dose was reduced for nose bleeds, dry skin, or hyperlipidemia. During the reaction skin toxicity questionnaires were completed weekly. Nine concurrent patients receiving only radiation completed identical forms. RESULTS: Etretinate did not intensify the skin reaction but did prolong it by 2 weeks. At a median follow-up of 2 years the relapse-free survival rate in complete responders was similar to stage-matched concurrent and historic control subjects. CONCLUSIONS: Both radiation and etretinate can be given together with acceptable toxicity and without compromising either therapy.

Administration, Oral↗
PubMed1992

An increase in thymocyte proliferation during pseudopregnancy in two inbred strains of rat.

Coitus is a unique physiological event which may result in internal fertilization, whereby active allogeneic spermatozoa are presented to the female host which can invade her tissues. Sterile coitus on the other hand, stimulates the uterine cervix in the rat and induces a physiological state of pseudopregnancy which interrupts the normal pattern of the oestrous cycle and establishes a persistent dioestrous state. This state is hormonally controlled and in its early stages is not dissimilar from that of true pregnancy. Pregnancy hormones are known to influence the immunological status of the female. Thymic observations during early pseudopregnancy showed interstrain differences in weight, cell content and thymocyte proliferation. Pooled data indicated increased cell density on days 3, 4 and 5 of pseudopregnancy associated with a peak of mitotic activity on day 3 in both strains. The timing of this proliferative activity seems to reflect the needs of the immune system in its putative response to mating and implantation.

Animals↗
PubMed1992

Lymphoid tissue changes during early syngeneic pregnancy in the RT1u rat.

An active immunological response by the female to mating and pregnancy is important, if not essential, to successful reproduction. Alloantigens which have been demonstrated on spermatozoa include histocompatibility antigens. In the enigmatic success of the fetal allograft, the conceptus survives owing to failure of the mother either to initiate or complete the process of rejection. In this study, AO(RT1u/AgB2) female rats were caged with male rats of the same strain. Observations were obtained from the first 5 days of their postcoital period, identifying lymphoid tissue changes which are due to the presence of the ejaculate and early products of conception in the female reproductive tract. A significant increase in intrathymic proliferation by day 3 is thought to be a hormonal effect induced by the cervical stimulation at mating. The postcoital exodus of lymphocytes from the thymus is possibly in response to coitus and induced by the seminal plasma to safeguard the implanting conceptus.

Animals↗
PubMed1992

Pigmented villonodular synovitis of the knee. The results of total arthroscopic synovectomy, partial, arthroscopic synovectomy, and arthroscopic local excision.

Twenty-five patients who had had a diagnosis of pigmented villonodular synovitis of the knee were followed for an average of four and one-half years (range, two to ten years) after arthroscopic treatment. Five patients had had localized lesions and had been managed with local resection; all five had improvement, with no apparent recurrence. The remaining twenty patients had had diffuse disease. Of these twenty, eleven had had a complete arthroscopic synovectomy. All eleven had definite improvement in pain and function, and almost all had a decrease in synovitis and an increase in the range of motion of the knee; the disease recurred in only one. The other nine patients had had a partial arthroscopic synovectomy. Although most had some improvement in function and range of motion and a decrease in pain and synovitis, the disease recurred in five of the nine. Thus, in the patients who had had diffuse pigmented villonodular synovitis, the rate of recurrence was lower in those who had had a complete arthroscopic synovectomy than in those who had had a partial arthroscopic synovectomy (p = 0.01).

Adolescent↗
PubMed1991

A predominance of the T cell receptor V gamma 2/V delta 2 subset in human mycobacteria-responsive T cells suggests germline gene encoded recognition.

Little is known about the nature of Ag recognition by the TCR-gamma delta. The recent observation that gamma delta T cells preferentially recognize mycobacterial Ag provides a model to examine the molecular basis of gamma delta-TCR recognition. Here, examination of the Mycobacteria-stimulated peripheral blood T cells with TCR-specific mAb revealed a predominance of T cells bearing V gamma 2/V delta 2 gene products. PCR cloning and sequence analysis of the TCR chains demonstrated extensive junctional diversity indicating that the response was polyclonal. The marked in vitro gamma delta T cell response to Mycobacteria was also detected in newborns before encounters with foreign Ag and exclusively involved the same V-gene usage observed in adults. Together, these results suggest that a major mechanism of gamma delta T cell reactivity involves recognition mediated by germline-encoded segments of the TCR.

Adult↗
PubMed1991

Cancer promotion in a mouse-skin model by a 60-Hz magnetic field: I. Experimental design and exposure system.

The rationale for selection of an animal model, the experimental design, and the design and evaluation of an exposure system used in studies of 60-Hz magnetic fields are described. The studies were conceived to assay development of cancer and immune responsiveness in mice exposed to magnetic fields. The exposure system utilized a quadrupole-coil configuration to minimize stray magnetic fields. Four square-wound coil provided a uniform field within a volume occupied by 16 animal cages. The magnetic field had a mean flux density of 2 mT that varied less than +/- 10% within the volume occupied by animals' cages. The flux density decreased to less than 0.1 microT at a distance of 2 m from the coils. In each exposure system 32 animals could be housed in plastic cages.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1991

The HIV test and sexual behaviour in a sample of homosexually active men.

This paper aims to assess the effects of voluntary anti-HIV testing on homosexual sexual behaviour. A sample of 502 men were recruited from four different areas of England. The criterion for inclusion was 'any man who had had sex with another man in the previous 5 years'. Men were interviewed about their recent sexual behaviour, histories of sexually transmitted diseases, experience of HIV tests and attitudes to the test. Men with a history of sexually transmitted diseases were more likely to have had the test. Thirty-one percent of men reported passive anal sex in the last month and 19% had had unprotected passive anal sex. These behaviours were most often reported by those testing HIV antibody positive and least by those never tested. The findings suggest that homosexually active men who volunteer for an anti-HIV test are broadly similar to those who do not. The absence of any clear effects of the test alone on sexual behaviour suggests that the quality of counselling in this area needs urgent attention.

AIDS Serodiagnosis↗
PubMed1991

Service needs of stroke survivors and their informal carers: a pilot study.

This pilot study prepares the way for a controlled evaluation of counselling of disabled stroke survivors and their carers. It assesses feasibility of methods and outcome measures potentially useful in the main study. The study elicited information about the psychological, physical, social and service needs, and the feelings of stroke survivors and their informal carers. Twenty patients and their carers were interviewed separately in their own homes. Results describe research tools which were refined, and demonstrate several unmet needs in the psychosocial domain. The main findings were a requirement for more information about stroke and for counselling in relation to 'care' problems arising out of the disability of stroke disease and the changes in dependency produced.

Aged↗
PubMed1990

Abortion.

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Abortion, Legal↗
PubMed1990

Isolation and characterization of the human hepatic lipase gene.

Overlapping bacterial phage and cosmid genomic clones were isolated spanning an area of approximately 60 kilobases that contains the human hepatic lipase (HL) gene. It is composed of 9 exons spanning approximately 35 kilobases of DNA. The entire coding regions, the 5'-flanking sequences, and the exon-intron junctions were sequenced. The intron positions correspond to those of human lipoprotein lipase and canine pancreatic lipase, supporting the concept that these genes constitute a dispersed gene family of lipases and have evolved by duplication of a common ancestral gene. A region of the HL gene, which displays a significant homology with various other lipolytic enzymes and contains the putative catalytic site serine residue of HL, was encoded by exon 4. A major transcription start site of the human HL gene was located by primer extension analysis, 43 nucleotides upstream of the translation initiation codon. Two possible promoter elements were located 25 and 63 nucleotides upstream of the transcription initiation site: a "TATA" box-like sequence, TAATA, and a sequence found in the promoter region of many liver-specific genes, AGGTTAATTATTAAT. In addition, sequences homologous to glucocorticoid and cAMP-responsive elements were identified in the 5'-nontranscribed region.

Amino Acid Sequence↗
PubMed1990

Human T cell receptor-gamma and -delta chain pairing analyzed by transfection of a T cell receptor-delta negative mutant cell line.

Specific TCR V gamma and V delta segments are found to be coordinately used on subpopulations of gamma delta T lymphocytes. The reasons for this phenomenon are unknown, but may include the inability of particular chains expressing unique V delta and V gamma segments to physically associate. V delta 2 is typically used together with V gamma 2 on human peripheral blood gamma delta T lymphocytes. To examine whether V delta 2 can be used in conjunction with distinct V gamma segments, a TCR- mutant of the human gamma delta T cell line MOLT-13, which expresses parental TCR gamma (V gamma 1.3) but not TCR-delta protein, was transfected with plasmids containing full-length TCR-delta cDNA using either V delta 2 or V delta 3. TCR reconstitution was successful in both transfectants and resulted in TCR protein and RNA levels similar to that of the parental MOLT-13 cell line. These cell lines could be activated through their receptors as assessed by increases in cytoplasmic free calcium. These studies imply that physical constraints cannot explain the observed chain pairing preferences. Other possible explanations are discussed.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1990

Lecithin cholesterol acyl transferase deficiency: molecular analysis of a mutated allele.

The enzyme, lecithin cholesterol acyltransferase (LCAT), is responsible for the esterification of plasma cholesterol mediating the transfer of an acyl group from lecithin to the 3-hydroxy group of cholesterol. Deficiency of the enzyme is a well-known syndrome with a widespread geographic occurrence. We have cloned an allele from a patient homozygous for the LCAT deficiency. The only change that we could detect is a C to T transition in the fourth exon of the gene; this causes a substitution of Arg for Trp at position 147 of the mature protein. The functional significance of such a substitution with respect to the enzyme defect was demonstrated by transfecting the mutated LCAT gene in the cell line COS-1.

Alleles↗
PubMed1990

Self care--who does best?

A clinically evaluated study to assess the benefits of a self care programme in general practice is described. There was significant improvement in psychiatric morbidity at the 6-month follow up, which was maintained at one year. The capacity of Multidimensional Health Locus of Control scales to predict long term clinical improvement was demonstrated, suggesting that a predominantly internal control of reinforcement appears to be crucial to the successful adoption of self care practices. The clinical and educational benefits of such programmes in dealing with a wide range of psychophysical problems in primary care is discussed.

Adult↗
PubMed1990

Gay men, social support and HIV disease: a study of social integration in the gay community.

As part of a large study of the effects of HIV and AIDS on gay male sexual behaviour, we investigated the extent to which gay men in the UK have access to social support and informal care at times of illness. The study sample (n = 502) demonstrated high levels of willingness to disclose sexuality to others, sociability and social integration. Over 90% reported that they had access to people whom they could turn for practical help at times of temporary incapacity. Between 42% and 46% have known a person, or persons, with HIV symptomatic disease, AIDS or someone who has died of AIDS, although men recruited in larger towns and cities were more likely to know people at every stage of HIV infection and AIDS than those from smaller towns. Twenty-five per cent had provided practical help and support to at least one person with AIDS; men in this situation were more likely to have had a close friend, lover or former lover who had died of AIDS. It is argued that it is not possible to expect the gay community to provide fully for the non-medical care of its members and, whilst some needs can be fulfilled on an informal care basis, the demands of long-term serious illness are such that adequate support services should be available in the community.

Adolescent↗
PubMed1990

Occurrence of 222Rn and progeny in natural gas processing plants in western Canada.

In Western Canada, there are many plants that process natural gas to remove impurities (CO2, H2S, H2O) and recover natural gas liquids (propane, butane, etc.). Trace quantities of 222Rn present in the inlet stream are concentrated in streams rich with propane. Potential hazards to plant operators include direct inhalation of 222Rn and progeny; exposure to gamma radiation from short-lived progeny deposited inside equipment; or inhalation of 210Pb when contaminated equipment is opened for repair. Twenty-four plants operated by seven companies cooperated to assess these potential hazards. The findings indicate a substantial flux of 222Rn and progeny passing through the plants, but little accumulation of radionuclides. In no case was there evidence of significant exposure of plant operators or maintenance personnel to ionizing radiation. Further investigation of pipeline operations, and chemical operations using natural gas liquids as feed stock, is recommended.

Bismuth↗
PubMed1990

Factors influencing condom use in a sample of homosexually active men.

A sample of 502 homosexually active men were recruited from genitourinary medicine clinics and non clinic sources and interviewed in relation to their sexual behaviour and factors that might influence their use of condoms. Three hundred and eighty three men (76%) reported penetrative anal sex in the previous year. Ninety four (25%) had not used condoms in penetrative sex. Failure to use condoms was associated with unfavourable attitudes to them, not knowing close friends or partners who had HIV-related health problems, having fewer sexual partners and being in a closed monogamous relationship. On the other hand levels of awareness about the risks of unprotected anal sex and involvement in gay networks and social groups were not predictors of condom use.

Acquired Immunodeficiency Syndrome↗