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Biomedical subjects

R M Thomas

Publications and source records attributed to R M Thomas.

At least 91 records · Page 5Linked to original sources
PubMed1989

Risks of AIDS among workers in the "sex industry": some initial results from a Scottish study.

OBJECTIVE: To determine the extent to which workers in the "sex industry" in Edinburgh engage in activities with a high risk of infection with HIV. DESIGN: Cross sectional, single phase survey in which respondents were located by a non-random method ("snowballing"). SETTING: Research project coordinated by the Alcohol Research Group, Edinburgh. SUBJECTS: 205 Sex workers (102 male, 103 female) interviewed between July and December 1988. END POINT: Strategies to reduce risk of AIDS among people who buy and sell sexual services. MEASUREMENTS AND MAIN RESULTS: Data were elicited by a standardised interview which related to over 300 variables. A fifth of the study group had used drugs intravenously, and one in 12 reported that they had been found to be seropositive on HIV testing. Roughly a quarter of the study group sometimes engaged in unprotected sex with clients for more money, and a similar proportion sometimes did not seek medical advice even if they had genital or anal symptoms. CONCLUSIONS: People who buy and sell sexual services should be priority targets for health education and strategies to reduce their risk of AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Pulmonary agenesis as part of the VACTERL sequence.

Pulmonary agenesis is an uncommon anomaly that has been reported in isolation and in association with other congenital defects. Such defects include oesophageal atresia, cardiac malformation, horseshoe kidney, and anal atresia. Over a period of three years we have seen five neonates or fetuses with unilateral agenesis of the lung. All the cases had three or more anomalies seen in the VACTERL sequence in addition to the pulmonary atresia. None had a tracheo-oesophageal fistula. None were the products of consanguineous marriages. There had been no recurrence of this range of defects in any of the families at the time of writing. We suggest that pulmonary agenesis may occur as an alternative to tracheo-oesophageal fistula in the VACTERL sequence.

Abnormalities, Multiple↗
PubMed1988

Mohs micrographic surgery.

Mohs micrographic surgery is a precise method of skin cancer removal that offers the highest cure rate and conserves the maximal amount of normal tissue. It is indicated for recurrent tumors and certain primary basal cell and squamous cell carcinomas, but not for small, nonrecurrent, well-defined lesions. The fresh tissue technique permits the use of horizontal frozen sections for the complete microscopic examination of lateral and deep margins.

Anesthesia, Local↗
PubMed1987

Inhibition of multistage tumor promotion in mouse skin by diethyldithiocarbamate.

Diethyldithiocarbamate (DDTC) injected i.p. inhibits remarkably and in a dose-dependent manner 12-O-tetradecanoylphorbol-13-acetate (TPA)-decreased glutathione (GSH) peroxidase and TPA-induced ornithine decarboxylase (ODC) activities in mouse epidermis in vivo. DDTC is more potent in inhibiting these effects of TPA than 16 other antioxidants, free radical scavengers, thiol-containing compounds, and reduced glutathione (GSH) level-raising agents, even though some of these treatments are applied directly to the TPA-treated skin. DDTC also inhibits the effects of several structurally different tumor promoters and the greater GSH peroxidase and ODC responses produced by repeated TPA treatments. The inhibitory effects of DDTC on TPA-decreased GSH peroxidase and TPA-induced ODC activities are additive with those of Na2SeO3 and D-alpha-tocopherol (vitamin E). Interestingly, DDTC is a more effective inhibitor when it is administered after TPA, suggesting that DDTC may supplement, facilitate, and/or enhance the activity of the natural GSH-dependent detoxifying system protecting the epidermis against the oxidative challenge presumably linked to the tumor-promoting activity of TPA. When tested in the initiation-promotion protocols, DDTC inhibits to the same degree complete tumor promotion by TPA and stage 2 tumor promotion by mezerein, in relation with its identical inhibition of the GSH peroxidase and ODC responses to both TPA and mezerein. Moreover, the inhibition of the first stage tumor-promoting activity of TPA by DDTC may be attributed to its ability to inhibit TPA-induced DNA synthesis, a postulated component of the conversion phase of skin carcinogenesis when TPA is used as a stage 1 tumor promoter.

Animals↗
PubMed1987

Effects of combined treatments with selenium, glutathione, and vitamin E on glutathione peroxidase activity, ornithine decarboxylase induction, and complete and multistage carcinogenesis in mouse skin.

Several structurally different tumor promoters altered to various degrees both glutathione (GSH) peroxidase (EC 1.11.1.9) and ornithine decarboxylase (ODC, L-ornithine carboxy-lyase, EC 4.1.1.17) activities in mouse epidermis in vivo. At 5 h after their application to the skin, the complete tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) and the stage 2 promoter mezerein were the most potent in inhibiting GSH peroxidase activity and inducing ODC activity. In comparison, the effects of anthralin, phorbol-12,13-didecanoate, benzoyl peroxide, H2O2, and phorbol-12,13-dibenzoate were much smaller, whereas the nontumor promoter phorbol, the hyperplastic agent ethyl phenylpropiolate, and the stage 1 promoter 4-O-methyl TPA did not alter GSH peroxidase and ODC activities. Various treatments including i.p. injections of 40 micrograms of Na2SeO3 and 100 mumol of GSH and/or topical applications of 40 mumol of D-alpha-tocopherol (vitamin E) 20 or 15 min, respectively, before tumor promoter treatment inhibited in an additive manner the effects of either TPA or mezerein on both GSH peroxidase activity and ODC induction. Moreover, these Na2SeO3, GSH, and/or vitamin E treatments inhibited in the same additive manner the tumor-promoting activity of TPA in the initiation-promotion protocol. However, when tested in the 2-stage promotion protocol with 4 doses of TPA followed by twice weekly applications of mezerein, Na2SeO3 plus vitamin E and GSH plus vitamin E treatments inhibited remarkably the tumor-promoting activity of mezerein but were ineffective in the first stage of promotion. The sequence and magnitude for the effects of 7,12-dimethylbenz[alpha]anthracene (DMBA) on GSH peroxidase and ODC activities were very different from those of the tumor promoters. In contrast with their antitumor-promoting activity, the treatments with Na2SeO3 plus vitamin E and GSH plus vitamin E failed to inhibit the carcinogenicity of a single large dose of DMBA and even enhanced the induction of skin tumors by repeated applications of subcarcinogenic doses of DMBA. These results suggest that the promoting component of DMBA carcinogenesis may be different from that of TPA. Moreover, the anticarcinogenicity of Na2SeO3, GSH, and vitamin E may be linked to their ability to facilitate or enhance the activity of the natural GSH-dependent antioxidant protective system of the epidermal cells during the later stages of skin tumor promotion.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1986

Ion-exchange resin bezoar in a neonate.

A case of impacted ion-exchange resin causing intestinal obstruction associated with intraluminal calcification is described. This cause of bowel obstruction with intraluminal opacification has not previously been reported.

Bezoars↗
PubMed1984

Synthesis and physicochemical characterization of major fragments of human leucocyte interferon alpha 1.

Four oligopeptides corresponding to overlapping regions of the human leucocyte interferon alpha 1 (IFN) amino acid sequence have been synthesized by the solid-phase method. The physicochemical properties of these peptides were investigated by analytical ultracentrifugation and circular dichroism, absorbance, and fluorescence spectroscopies. IFNs 24-81 and 111-166 were shown to possess considerable ordered structure in solution. IFN 111-166 appeared to adopt a beta-stranded conformation, which could be reversibly unfolded by the addition of urea. Equimolar mixtures of IFNs 24-81 and 111-166 formed a noncovalent complex that was resistant to the formation of the Cys29-Cys139 disulfide bond found in native interferon alpha 1. Predictions of the secondary structure of interferon alpha 1 were made and the results compared to the measured properties of the fragments. In general, it was found that the prediction methods favored a highly alpha-helical conformation.

Circular Dichroism↗
PubMed1983

Identification by n.m.r. spectroscopy of a stable intermediate structure in the unfolding of staphylococcal beta-lactamase.

The unfolding of beta-lactamase (penicillinase) from Staphylococcus aureus by guanidinium chloride was followed by using n.m.r. spectroscopy. On the basis of the observation of resonances corresponding to histidine, tyrosine and other amino acid side chains, the existence of a stable partially folded species was demonstrated. These experiments provide detailed characterization of the intermediate that confirms and extends previous characterization by absorption and c.d. spectroscopy and by flow properties. In addition, they show that residues in the N-terminal third of the molecule are affected by the native-to-intermediate transition. Persistent non-equivalence of the two imidazole C2 proton resonances at high guanidinium chloride concentrations is discussed in terms of local sequence effects on the chemical shift.

Guanidine↗
PubMed1983

T cell regeneration after allogeneic and autologous bone marrow transplantation.

Venous blood T cell phenotypes were analysed with monoclonal antibodies after 11 allogeneic and 17 autologous bone marrow transplants. In seven cases studied in the early regenerative period, cells with a thymocyte phenotype were present in the blood. In the large majority of patients treated with both allografts and autografts there was an imbalance of phenotypic 'helper' and 'suppressor' T cell subsets with initially a relative and later an absolute increase of 'suppressor' T cells. This imbalance was still present at over 250 d in eight out nine cases. Suppressor T cells bearing HLA-Dr antigens were abundant in one case of fatal GVHD but not in another, and were also increased following two autografts. It is concluded that T cell phenotyping is not of diagnostic value in sick patients following bone marrow transplantation when graft-versus-host disease is suspected.

Adolescent↗
PubMed1983

Erythropoietin and cord blood haemoglobin in the regulation of human fetal erythropoiesis.

Erythropoietin was estimated by radioimmunoassay in serum from 78 cord blood samples, collected in the second and third trimesters in 72 pregnancies. In 43 samples obtained during or after normal pregnancy (from 19 to 42 weeks gestation) erythropoietin levels increased with gestation. Cord blood haemoglobin also increased with gestation, but the rate of increase was less during the last weeks of pregnancy. Erythropoietin levels were similar in the cord blood of infants of the same gestation, whether born vaginally or by caesarean section. The fetus can respond to severe anaemia or hypoxia with increased erythropoietin levels as early as 24 weeks gestation. Elevated erythropoietin levels were found in two out of eight infants born after labour in which there was 'acute' fetal distress, suggesting the presence of unrecognized chronic fetal hypoxia in these pregnancies.

Blood Transfusion, Intrauterine↗
PubMed1983

Identification of lymphocyte subsets in the newborn using a variety of monoclonal antibodies.

Using a small sample of peripheral venous blood, the normal range for lymphocyte subpopulations (T-cell, B-cell, T-suppressor cell, and T-helper cell) was defined in non-infected preterm and term infants. Lymphocyte subsets were identified using a variety of monoclonal antisera, and analysis was performed using a fluorescent activated cell sorter. Such methods allow an objective assessment of absolute numbers of cells per unit volume of whole blood. There was no significant difference in absolute numbers of lymphocyte subsets between term and preterm appropriate for gestational age (AGA) infants. Infants who were small for gestational age (SGA) had a significant deficiency in absolute numbers of total T-cells, helper and inducer T-lymphocytes, and B-cells compared with both term and preterm AGA infants. All newborn infants (term and preterm; AGA and SGA) had a highly significant increase in absolute numbers of both helper and suppressor T-lymphocytes compared with normal adults.

Antibodies, Monoclonal↗
PubMed1983

Lymphocyte subpopulations in primary immunodeficiency disorders.

Venous blood mononuclear cells from 42 children with primary immunodeficiency disorders and from controls matched for age were studied for lymphocyte subpopulations by E rosetting, surface immunoglobulin, and a panel of anti T cell monoclonal antibodies (OKT series). In 3 cases of severe combined immunodeficiency (SCID) due to adenosine deaminase deficiency, very few circulating T or B cells were found. The other 7 cases of SCID all had normal or, in 3 cases, very high numbers of circulating B cells, but in 6 of these very few cells showed T cell markers. One child had very high numbers of B cells and T cells with an immature pattern of reactivity similar to that found on common thymocytes. In T cell deficient children no consistent pattern was found, but in those with cartilage hair hypoplasia with immunodeficiency there was a low helper (OKT4) to suppressor (OKT8) ratio and high numbers of circulating OKT10 positive cells. In cases of X-linked agammaglobulinaemia circulating B cells were not found but the pattern of T cell markers was normal. In cases of common variable hypogammaglobulinaemia there was a wide scatter of helper (OKT4) to suppressor (OKT8) cell ratios. Five children were studied before and after treatment with the synthetic thymic hormone preparation TP5. There were appreciable alterations in the pattern of staining with anti T cell monoclonal antibodies in 4 of these cases, but in 1 case only was this accompanied by improvements in clinical and immune function.

Agammaglobulinemia↗
PubMed1981

Pancuronium during mechanical ventilation speeds recovery of lungs of infants with hyaline membrane disease.

Spontaneous breathing during mechanical ventilation in newborn infants may damage the lung. To find out whether the prevalence of lesions which might be due to trauma was reduced by muscle relaxation, fifty infants who required mechanical ventilation of hyaline membrane disease were randomly assigned to treated and control groups. The treated infants were kept muscle relaxed with pancuronium bromide until they needed a FiO2 of 0.40 or less during ventilation. The mean birthweight, gestational age, age at entry to the trial, duration of intubation and ventilation, FiO2 during the acute phase of the illness, and ventilator pressures were closely comparable in the two groups. Two of twenty-six treated infants and one of twenty-four controls died. Four treated and five control infants acquired pneumothoraces and/or interstitial emphysema. The length of time that the treated infants required added oxygen was significantly less than in the control infants. All treated infants were breathing room air spontaneously by one month of age whereas seven control infants were still dependent on added oxygen, needing an average FiO2 of 0.35 to achieve a mean PaO2 of 6.5 kPa (49 mm Hg). These seven infants required added oxygen until they were 5-18 (mean 10) weeks old. Muscle relaxation during mechanical ventilation for hyaline membrane disease speeds recovery of the lungs, probably owing to a reduction in traumatic damage.

Airway Resistance↗