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Biomedical subjects

S M Robinson

Publications and source records attributed to S M Robinson.

At least 73 records · Page 4Linked to original sources
PubMed1988

Cigarette smoking and the thermic responses to isocaloric meals of varying composition and palatability.

The 4-h thermic responses to glucose and a liquid formula meal (Study 1), and to a solid food 'breakfast' meal and the liquid formula meal (Study 2) were measured in a group of young weight-stable female subjects. The groups recruited for the two studies consisted of nine smokers and seven non-smokers (Study 1) and six smokers and eight non-smokers (Study 2). The habitual smokers presented after a 12-h abstention from cigarettes but were permitted to smoke following the meal; their thermic responses were thus due to the combined thermogenic effects of smoking and feeding. The mean thermic responses to all three types of meal were greater for the smokers than for the non-smokers, and the magnitude of this difference was similar irrespective of the type of meal given (range 52 kJ-70 kJ). The thermic responses to the liquid formula meal tended to be greater than those to an isocaloric glucose load for smokers and non-smokers (Study 1). In Study 2, the increase in energy expenditure occurring during the first hour following the 'breakfast' meal was consistently greater than the 1-h response to the liquid formula meal. The larger thermic response to feeding to all three meal-types observed in the groups of smokers when compared with non-smokers, is attributed to the actions of cigarettes smoked (mean 4.6) during the period of measurement. It is concluded that whilst the thermic response to feeding is augmented in cigarette smokers this increase is an additive effect and is independent of the size and nature of the thermic effect of the meal.

Adult↗
PubMed1987

Adaptations in protein metabolism during lactation in the rat.

1. The activities of two hepatic enzymes that participate in the regulation of amino acid oxidation and urea synthesis were measured in lactating rats (day 15 of lactation) and virgin controls. The enzymes were alanine aminotransferase (EC 2.6.1.2) and argininosuccinate synthase (EC 6.3.4.5). Carcasses of the dams were also analysed. 2. Changes in the activities of both enzymes in dams fed ad lib. on a diet containing an excess of protein indicated that amino acid oxidation was depressed. In dams restricted in protein to the level of intake of their controls but allowed to satisfy their needs for energy, enzyme activities were significantly reduced. In these animals lean tissue catabolism supplemented the dietary protein supply. 3. This adjustment in protein metabolism which effectively spares protein for milk-protein synthesis could be explained either by a reduction in the availability of substrate in the liver, or by the intervention of an anabolic hormone secreted in lactation.

Adaptation, Physiological↗
PubMed1987

Identification and subcellular distribution of cornified envelope precursor proteins in the transformed human keratinocyte line SV-K14.

SV-40 transformed human foreskin keratinocytes (line SV-K14) develop under conditions of serum starvation the competence to form cornified envelopes that are characteristic of terminally differentiating epidermal cells. In this cell line, the final assembly of the envelope does not occur spontaneously but must be induced using a calcium ionophore. Five potential precursor proteins with molecular weights of 140K, 90K, 61K, 53K, and 36K, respectively, could be detected in the extracts of envelope competent and noncompetent cells. The 61 kD and the 36 kD precursors were specifically decorated in immunoblots when using an antiserum directed against the purified cornified envelope of SV-K14 cells. The 140 kD protein was identified as involucrin by means of a commercial anti-involucrin antibody. Part of the 61 kD protein was found to be inserted into the plasma membrane after the cells gained envelope competence. The set of precursor proteins used by SV-K14 cells differed markedly from those described in the literature for epidermal cells in vivo and for normal human keratinocytes in vitro. Furthermore, cyanogen bromide cleavage of purified envelopes from transformed and normal keratinocytes revealed a completely different peptide pattern. This indicates that the exact molecular composition of the cornified envelope may not be strictly determined and may vary according to the availability of potential substrate proteins at the very moment when the cross-linking enzyme, the plasma membrane associated transglutaminase, becomes functional.

Cell Line↗
PubMed1986

Sex differences in the shape of the sexually dimorphic nucleus of the preoptic area and suprachiasmatic nucleus of the rat: 3-D computer reconstructions and morphometrics.

Three-dimensional images of nuclei facilitate morphological comparisons between differing animal groups. As revealed by computer-assisted techniques, the greater volume in male rats of the sexually dimorphic nucleus of the preoptic area was not proportional in all directions. The nucleus was more elongated in males than females, indicating a sex-dependent shape. This study also indicated that the volume of the suprachiasmatic nucleus was larger in males.

Animals↗
PubMed1986

Treating the patient with digital hypersensitivity.

Digital hypersensitivity is a functionally disabling condition, which often responds to conservative treatment with structured sequential desensitization. This case study describes the treatment hierarchy as the patient responds with objective improvement at each stage.

Adult↗
PubMed1985

Abnormal maturation pathway of keratinocytes in psoriatic skin.

We compared the maturation pathway of normal and psoriatic epidermis using three different markers: (1) Involucrin, which is normally detected in the stratum granulosum in normal skin, was detected in all but the basal layer of involved psoriatic skin; (2) an antigen, recognized by the murine monoclonal antibody psi 3, was present in all but the basal layer of involved psoriatic skin but was absent from uninvolved and normal skin; (3) fibronectin, which normally localizes in the dermis and the epidermal-dermal junction, was also detected intra- and extracellularly in the psoriatic epidermis. These results indicate that the alterations in keratinocyte maturation found in psoriasis do not arise from a truncation of the normal maturation pathway but rather reflect the onset of an abnormal pathway of differentiation characterized by the expression of psi 3 antigen and fibronectin and the premature appearance of involucrin.

Antibodies, Monoclonal↗
PubMed1985

A genetic variant in the morphology of the medial preoptic area in mice.

Inbred mice of the DBA/2J and C57BL/6J strains are known to differ in physiological and behavioral characteristics that are partially controlled by nuclei in the preoptic area/anterior hypothalamus. We describe a distinguishing nucleus of darkly staining, densely packed cells, which we term the medioventral pars compacta (MVPC), within the medial preoptic nucleus of DBA/2J, but not C57BL/6J mice. The analysis also indicates that this nucleus is nearly 80% larger in volume in females vs males of the DBA/2J strain. The strain difference may be used to define genetic influences on this neuroanatomical and functional property.

Animals↗
PubMed1985

Reexpression of fetal characters in simian virus 40-transformed human keratinocytes.

Normal human keratinocytes are able to stratify, form cornified squames, and terminally differentiate in tissue culture. These properties are frequently impaired by malignant transformation. In the present paper, we show that, in addition, transformation by SV40 results in the coordinate reexpression of a whole set of fetal characters. Moreover, a comparison of two SV40-transformed human keratinocyte cell lines, one still showing a certain degree of stratification and terminal differentiation (HE-SV) and the other almost completely unable to differentiate (SVK14), suggests that the impairment of differentiation and the intensity of reexpression of fetal markers are correlated. Particularly, a set of three keratin polypeptides, absent in adult stratified epithelia but normally found in the nonstratified fetal epidermis, is present in much larger amounts in SVK14 cells than in HE-SV cells. On the other hand, the inability of SVK14 cells, in contrast to HE-SV cells, to form cornified envelopes seems to be due to the inability of those cells to accumulate involucrin.

Basement Membrane↗
PubMed1979

Regional alveolar gas composition and lung function in sheep.

The influence of regional alveolar oxygen and carbon dioxide tensions on the distribution of lung blood flow and gas exchange was studied in unanaesthetised sheep. Right apical lobe (RAL) hypoxia, induced by administering nitrogen or nitrogen/oxygen mixtures to the lobe, stimulated a prompt, graded and well sustained reduction in lobar blood flow. Maximum hypoxia was accompanied by an approximate 65% reduction in perfusion, a significant fall in RAL carbon dioxide tension and output, a reversal of lobar oxygen flux and an average 13 Torr fall in arterial oxygen tension. The reduction in perfusion and gas exchange persisted in the face of elevated systemic oxygen tensions produced by giving pure oxygen instead of air to the remainder of the lung (RL). Mild RAL hypercapnia potentiated the hypoxia-induced change in perfusion and gas exchange. During lobar hypoxia RL blood flow and gas exchange increased to maintain total pulmonary gas exchange at an essentially constant level. RAL hyperoxia did not significantly alter the distribution of perfusion or gas exchange.

Animals↗
PubMed1978

An animal model for the study of regional lung function.

An animal model for the study of regional lung function is described. In sheep, the bronchus to the right apical lobe (RAL) of the lung arises directly from the trachea. A tracheal divider, inserted under local anesthesia via a permanent tracheostomy, was used to separate the ventilation of the RAL from that of the rest of the lung. Lobar blood flow was estimated from the RAL contribution to the pulmonary clearance of an intravenous bolus of 85Kr. Gas exchange was measured by conventional methods. Expressed as a percentage of the value obtained for the whole lung, lobar expired volume was 14.7 +/- 4.3%, capillary perfusion was 12.3 +/- 4.2%, oxygen uptake was 14.7 +/- 4.9%, and carbon dioxide production was 13.4 +/- 5.5% (mean +/- SD of 25 studies in 11 animals breathing air). The model permits the study of experimental conditions confined to a single lobe of the lung and offers the advantages of an intact chest wall, spontaneous ventilation and an unanesthetized animal.

Animals↗
PubMed1978

The stability of A1,B29-adipoylinsulin to chemical and enzymatic degradation.

The degradation of A1,B29-adipolyinsulin by partial hydrolysis, by disulphide-bond exchange, by chymotrypsin and by a cytosolic enzyme fraction of rat liver was measured and compared with that of A1,B29-diacetylinsulin and insulin. The cross-linked insulin is, in general, more resistant than insulin itself or the diacetylated derivative. However, in the case of enzymatic degradation, A1,B29-diacetylinsulin resembles more the cross-linked derivative than insulin. This provides evidence that the properties of A1,B29-adipoylinsulin could not in all circumstances be attributed to its 'proinsulin-like' structure.

Animals↗