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Biomedical subjects

R Smith

Publications and source records attributed to R Smith.

At least 1,405 records · Page 78Linked to original sources
PubMed1981

The effects of different dose regimes of D-SER(TBU)6-LHRH-EA10 (HOE 766) in subjects with hypogonadotrophic hypogonadism.

Eight male patients with hypogonadotrophic hypogonadism were treated with injections of a long acting LHRH analogue, HOE 766. Six of the patients were on daily subcutaneous injections of 5 microgram of this analogue at the start of this study and were changed to alternate-daily injections of the same dose for 1-3 months. They were then treated with twice-daily injections of 0.5 microgram HOE 766, as was another subject not previously treated. The HOE 766 twice-daily was given alone for 1 or 2 months and then sex steroid replacement therapy was added to this for a further 4-5 months. There was no clinical improvement or rise in plasma testosterone levels until sex steroid therapy was commenced. Basal LH and FSH levels and peak responses to 100 microgram LHRH remained low throughout the study. It is concluded that these variations in dose and interval of administration do not overcome the lack of pituitary response which is a feature of prolonged treatment with LHRH analogues.

Adolescent↗
PubMed1981

The effects of a met-enkephalin analogue on ACTH, beta-LPH, beta-endorphin and MET-enkephalin in patients with adrenocortical disease.

Thirteen patients with either Addison's disease, or Cushing's disease treated by bilateral adrenalectomy, were infused with the long-acting met-enkephalin analogue DAMME. In patients with Addison's disease significant and pronounced falls in ACTH and N- and C-terminal beta-LPH were seen; chromatography suggested that beta-endorphin fell concomitantly. Three out of four patients with Cushing's disease who had not received pituitary irradiation, also showed a decrease in plasma ACTH and N- and C-terminal beta-LPH; however, no change was seen in any of the irradiated patients. The changes were naloxone reversible. The levels of plasma met-enkephalin were normal and did not change after DAMME in any group of patients. These results are interpreted as suggesting that there are inhibitory opiate receptors controlling the release of ACTH, beta-LPH, and beta-endorphin.

Addison Disease↗
PubMed1981

Use of plaque assays to study thyroglobulin autoantibody synthesis by human peripheral blood lymphocytes.

Plaque assays have been used to study thyroglobulin autoantibody synthesis and total immunoglobulin production by cultures of peripheral blood lymphocytes from patients with Hashimoto's thyroiditis. Freshly isolated Hashimoto or normal lymphocytes contained small numbers (7-1300) of total IgG plaque-forming cells (PFC) and total IgM PFC, but specific thyroglobulin antibody PFC was undetectable. After 5-8 days' culture with pokeweek mitogen (PWM), total IgG and IgM PFC were markedly increased to a geometric mean of 10,140 (8414-12,220) IgG PFC and 3450 (163-7534) IgM PFC per 10(6) cultured lymphocytes (95% confidence limits in parentheses). Furthermore, a mean of 63 (22-287) specific IgG thyroglobulin antibody PFC per 10(6) lymphocytes were detectable in cultures of Hashimoto lymphocytes. The IgG thyroglobulin antibody PFC were stimulated by Epstein-Barr virus (EBV) infection, suggesting that EBV infection may be useful in obtaining monoclonal thyroid autoantibodies.

Adult↗
PubMed1981

Congenital duodenal diaphragm in an adult.

A case of congenital duodenal diaphragm has been presented. The clinical features of protracted vomiting, epigastric pain and discomfort after meals with a gastric splash occurring at any age, the biochemical features of profound hypokalaemia and hypochloraemic alkalosis, and the radiological demonstration of a diaphragm have been shown to be of diagnostic significance. The operation of vagotomy and gastroenterostomy was unsuccessful in this case, and a literature review suggests that duodenotomy with excision of the diaphragm is the preferred method of treatment.

Duodenum↗
PubMed1981

Immunization with purified protein antigens from Streptococcus mutans against dental caries in rhesus monkeys.

Protein antigens I, I/II, II, and III were prepared from Streptococcus mutans (serotype c). Their immunogenicities and protective effects against dental caries were investigated in 40 rhesus monkeys kept entirely on a human-type diet, containing about 15% sucrose. Antigens I, I/II and, to a lesser extent, antigen II induced significant reductions in dental caries, as compared with sham-immunized monkeys. This was achieved with 1 or 2 doses of antigen, the first of which was administered with adjuvant (Freund incomplete adjuvant or aluminum hydroxide). There was no reduction in caries in monkeys immunized with antigen III. The reduction in caries in the animals immunized with antigens I or I/II was comparable to that in monkeys immunized with whole cells. Protection against caries was associated predominantly with serum and gingival crevicular fluid immunoglobulin G antibodies, which appeared to be directed against the antigen I determinant, but antibodies to antigen II, though not to antigen III, were also protective.

Animals↗
PubMed1981

Thermal diffusivity in finite cylindrical specimens of dental cements.

1. A method has been developed and described for obtaining accurate thermal diffusivity values for dental cements and other restorative materials. This method employs specimens of a short cylindrical geometry which are readily fabricated from simply-constructed molds. 2. Results obtained for polycarboxylate and glass-ionomer cements show that the diffusivity values are mainly in the range of 2-3 x 10-3 cm2 s-1. Thus, the thermal characteristics of these materials are suitable if the cements are used as insulating bases below amalgam restorations. 3. thermal diffusivity values are a potential tool for investigating structure/property relationships in restorative materials, being sensitive to moisture content, powder/liquid ratio, and other compositional variables.

Dental Cements↗
PubMed1981

Correlation of collagen synthesis and procollagen messenger RNA levels with transformation in rat embryo fibroblasts.

A line of normal rat embryo fibroblasts was transformed with N-methyl-N'-nitro-N-nitrosoguanidine (a chemical carcinogen), SV40 and polyoma virus (two DNA viruses), and Rous sarcoma virus (an RNA tumor virus). In this study, we report a comparison of the levels of collagen synthesis and procollagen messenger RNA (mRNA) in 13 lines selected after transformation with one of these agents. Collagen synthesis and procollagen mRNA levels were compared with the degree of transformation determined from morphology, saturation density, growth in agarose, and tumorigenicity in nude mice. Each class of transformants had a characteristic level of collagen synthesis; this level correlated inversely with the degree of transformation of the rat embryo fibroblasts. In N-methyl-N'-nitro-N-nitrosoguanidine and SV40 transformants which were moderately transformed, collagen synthesis was hardly affected, but, in polyoma virus and Rous sarcoma virus transformants which were more severely transformed, collagen synthesis was 30 to 48% and 12 to 25%, respectively, of control levels. Type I procollagen mRNA activity measured in RNA from nine of the lines by an in vitro translation assay also decreased with increasing severity of transformation. Procollagen mRNA levels were reduced to about one-half of control levels in one SV40 transformant and to 17 to 23% of controls in polyoma virus and Rous sarcoma virus transformants. We conclude that, in this series of rat fibroblast lines, transformation with different agents resulted in characteristic levels of collagen synthesis and that collagen synthesis was most reduced in the cells which were most transformed by other criteria.

Animals↗
PubMed1981

A radioimmunoassay for serum and gingival crevicular fluid antibodies to a purified protein of Streptococcus mutans.

A solid-phase radioimmunoassay was developed to measure serum IgG antibodies to a purified protein antigen I/II prepared from Streptococcus mutans. The assay was specific to this antigen and significant binding of 125I-radiolabelled antiserum was found only in sera from rhesus monkeys immunized with the antigen I/II but not in sham-immunized monkeys or those immunized with streptococcal antigen III. A very significant correlation was found in serum IgG antibodies tested by the radioimmunoassay and an immunofluorescent technique (r = 0.88, P less than 0.001). The sensitivity of the double-layer radioimmunoassay was increased 10 times by the addition of a third antibody layer and this enabled gingival crevicular fluid antibodies to be measured. Comparison of paired samples of serum and crevicular fluid revealed a very significant correlation between IgG antibodies to streptococcal antigen I/II in the the two fluids (P less than 0.001). These findings suggest that serum antibodies can reach the tooth surface via gingival crevicular fluid.

Animals↗
PubMed1981

The effects of visual discrimination of image movement across the stationary retina.

The visual performance of human subjects has been investigated during presentation of a digital display moving at constant velocity with regard to the stationary eye. The display was presented for brief periods (10-80 ms) at different luminance levels (0.5-8 cd/m2), contrast levels (1-16), and display sizes (character height 12-24' of arc). The probability of correctly identifying the display decreased to 90% when the velocity reached 3-4 degrees/s. Performance was improved by increasing digit size, decreasing exposure time, or increasing display luminance. Theoretical arguments have been adduced to indicate the usefulness of the results in predicting performance during continuous display exposure.

Form Perception↗
PubMed1980

1,25-dihydroxy-vitamin D3: a new treatment for hypoparathyroidism.

Eleven subjects aged four to 76 years with primary hypoparathyroidism have been treated with 1,25-dihydroxycholecalciferol (1,25-D3). Five subjects were not on vitamin D analogues before starting this drug. 1,25-D3 was found to be an effective treatment and a rapid biochemical response to dose adjustments was observed. In two subjects hypercalcaemia and reversible renal failure occurred. Thiazide-type diuretics necessitated dose reductions in a further two subjects. A scheme for starting hypoparathyroid subjects on this treatment is suggested. The need for regular biochemical assessment and awareness of possible drug interactions is emphasised. It is felt that 1,25-vitamin D3 has practical advantages over traditional forms of vitamin D in the treatment of hypoparathyroidism.

Adult↗