Biomedical subjects
Publications and source records attributed to E Thomson.
Laugier-Hunziker syndrome is an extremely rare disorder but is of some interest to dental practitioners. The importance of the condition relates to it being included in the differential diagnosis of pigmentary disorders of the oral mucosa with associated nail involvement. Two cases of the syndrome are described.
Steroids have potent actions on the brain which can be categorized as; (i) fast (approximately ms-s), (ii) intermediate (h-days), (iii) long-term reversible (days-weeks) and (iv) long-term irreversible. Here attention is focussed on the intermediate and long-term reversible effects of steroids with emphasis on glucocorticoids and oestrogen. Glucocorticoid negative feedback is generally classified as fast, delayed and long-term. Fast negative feedback would appear to depend mainly on a reduction in pituitary responsiveness to corticotrophin releasing factor-41 (CRF-41) and possibly arginine vasopressin (AVP). Delayed feedback is mediated by reduced AVP release into hypophysial portal blood and blockade of the ACTH response to CRF-41. Long-term negative feedback is a consequence of reduced CRF-41 and AVP release into portal blood. Lesion and electrical stimulation studies pinpoint the paraventricular nuclei as the main site at which glucocorticoids act to control ACTH release. Oestrogen at physiologically low plasma concentrations inhibits gonadotrophin secretion. At physiologically high plasma concentrations, such as those that occur during the preovulatory surge, oestradiol-17 beta stimulates the biosynthesis of LHRH mRNA and LHRH and the release of LHRH into hypophysial portal blood. Oestradiol also increases pituitary responsiveness to LHRH. The action of oestrogen on LHRH neurons is probably mediated by interneurons and may involve disinhibition; this view is supported by our in situ hybridization studies which show that oestrogen, in its positive feedback mode, significantly reduces the synthesis of proopiomelanocortin mRNA in arcuate neurons which when active are likely to inhibit LHRH neurons. The mechanism of action of oestrogen on the pituitary gland is not yet established, but clues from the action of the priming effect of LHRH suggests that oestrogen may potentiate phosphoinositide second messenger cascades. LHRH priming involves the synthesis of a 70 kDa protein the N-terminus of which is identical to an oestrogen-induced protein in the ventromedial hypothalamic nucleus involved in lordosis, and to that of phospholipase C alpha. Attention is drawn to the remarkable economy of the system by which a single steroid, oestrogen, has effects on the brain and pituitary gland which result in a co-ordinated sequence of amplifier cascades which lead first to the ovulatory surge of luteinizing hormone and then to mating behaviour, both of which are obviously essential for continuation of the species.(ABSTRACT TRUNCATED AT 400 WORDS)
We have been able to establish stable, minor histocompatibility antigen-specific, non-cytolytic, MHC-class II-restricted suppressor T cell clones and lines. These suppressor T cells rearrange, transcribe, and express alpha beta T cell receptor. An unusual feature of all our clones and lines is the co-expression of CD4 and CD8 molecules on their cell surface, a characteristic which may distinguish them from conventional helper and cytolytic T cells in this system. The fact that multiple, phenotypically and functionally identical cell lines were reproducibly obtained from this system indicates that antigen-specific down-regulation of immune functions in certain circumstances is mediated by T cells that are neither conventional cytolytic nor helper T cells.
Our aim was to determine whether oestrogen administered to ovariectomized rats in a manner which stimulates the release of LHRH also stimulates the synthesis of LHRH mRNA. Adult female Wistar rats were ovariectomized under halothane anaesthesia between 09.00 and 11.00 h of dioestrus, immediately injected with either oil or 10 micrograms oestradiol benzoate (OB) and then killed by cervical dislocation between 16.00 and 17.00 h of the next day (presumptive pro-oestrus). In-situ hybridization carried out with a 30 mer, 32P-labelled, oligonucleotide probe complementary to LHRH mRNA showed that the concentrations of LHRH mRNA in perikarya in the medial preoptic area, diagonal band and medial septum were significantly greater in OB-compared with oil-treated rats. Plasma LH concentrations were significantly increased in three out of four of the OB-treated rats. These results show for the first time that as well as stimulating LHRH and LH release, oestrogen positive feedback also stimulates the synthesis of LHRH mRNA.
The heat production for two breeds of laying hens was estimated by indirect respiration calorimetry. Using multiple linear regression techniques, egg energy output was identified as a significant contributor to variability in heat production (P = .0113). Heat production of the hens decreased with increasing egg energy output. Body weight, feed intake, egg energy output, and genetic stock were all significant contributors to variability in heat production. Comparisons of traditional techniques (relating energy balance to metabolizable energy intake) and multiple regression techniques (heat production as a function of body weight, feed intake, egg energy output, and genetic stock) for evaluating calorimetry data were made.
The relationship between desired and achieved fertility may be misspecified by excluding husbands' fertility desires or by confounding effects of shared desires with the resolution of conflicting desires. Using couple data from the classic Princeton Fertility Surveys, we find relatively large husband effects on fertility outcomes as well as unique effects of spousal disagreement. Wives and husbands were equally likely to achieve fertility desires, and disagreeing couples experienced fertility rates midway between couples who wanted the same smaller or larger number of children. These conditions do not hold, however, when we include willingness to delay births for economic mobility as part of the measure of fertility desires. Among couples who both wanted a third child, only husbands' willingness to delay births had significant negative effects on birth rates.
By using radioiodinated monoclonal antibodies we have estimated that there are about 600 000 copies of sialoglycoprotein alpha (synonym glycophorin A) and 80 000 copies of sialoglycoprotein delta (synonym glycophorin B) per normal human erythrocyte. Erythrocytes expressing the product of only one alpha gene contain about 300 000 copies of alpha/cell. Two erythrocyte types containing alpha-delta hybrid molecules were studied. Those with heterozygous expression of the (alpha-delta)Mi.V gene contain about 100 000 alpha-delta copies per cell, whereas those with heterozygous expression of the En(UK) gene contain about 80 000 alpha-delta copies/cell. Erythrocyte types containing delta-alpha hybrid molecules were also studied. About 200 000 copies of (delta-alpha)Dantu were measured in cells with heterozygous expression of the (delta-alpha)Dantu gene (donor M.P.), whereas about 315 000 copies of the putative (delta-alpha)Dantu hybrid were found on the erythrocytes of donor J.O. [which also have heterozygous expression of the putative (delta-alpha)Dantu gene]. The erythrocytes of donor M.P. have normal levels of alpha, whereas those of donor J.O. have only about half-normal levels. It is proposed that the hybrid sialoglycoprotein of donor J.O. is of alpha-delta-alpha composition [(alpha-delta-alpha)Dantu] rather than delta-alpha and results from a double cross-over analogous to that which gives rise to haemoglobin Parchman.
The study assessed the psychometric properties of the Medical Communication Behavior System. This observation system records time spent by the physicians and patients on specific behaviors in the categories of informational, relational, and negative situation behaviors by using hand-held electronic devices. The study included observations of 101 genetic counseling sessions and also assessed the outcome measures of patient knowledge and satisfaction. In addition, 41 of the sessions were rated using the Roter Interactional Analysis System, and 20 additional control subjects completed the post-counseling information without being observed to examine the effects of recording the session. Results showed good interobserver reliability, and evidence of concurrent, construct, and predictive validity. No differences were found between the observed and unobserved groups of any of the outcome measures.
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Energy and nitrogen (N) metabolism were studied in 6-week-old male birds taken from 4 lines of chickens selected for 10 generations for increased weight gain (line W), increased food consumption (line F), increased conversion of food to gain (line E) or at random (controls, line C). Calorimetric measurements were made 8 times on each line while fed ad libitum in large open-circuit respiration chambers for 3 d, and 11 to 13 times without food in smaller closed-circuit respiration chambers for 24 h. The F line ate 60% more food, produced 90% more excreta and 34% more heat and retained 80% more energy and 35% more N in their bodies than lines E and C. Line W was intermediate. When differences in body weight were taken into account, the E and W lines had lower heat production than the C line, while the F line ate 40% more food, produced 30% more heat and retained 70% more energy and 30% more N than the E line. In lines W, F, E and C respectively, the mean metabolisability of dietary energy (%) was 69.4, 62.9, 70.1 and 67.8; the fasting heat production (mean +/- SE) was 481 +/- 9, 569 +/- 10, 485 +/- 9, and 508 +/- 9 kJ/kgW d; the net availability of metabolisable energy (NAME) was 0.68 +/- 0.05, 0.76 +/- 0.04, 0.85 +/- 0.06 and 0.73 +/- 0.04; the estimated daily maintenance energy requirements were 671 +/- 15,866 +/- 14,701 +/- 13, and 742 +/- 11 kJ ME/kgW; and the proportion of N retained per unit increase in N intake was 0.38 +/- 0.08, 0.50 +/- 0.06, 0.56 +/- 0.10 and 0.53 +/- 0.06. The contribution of line differences in the above traits to large line differences in efficiency of food utilisation is discussed.
Human urine concentrates, prepared with the use of XAD-2 resin, are shown to be potent inducers of sister-chromatid exchanges, and especially of chromosomal damage and cell-cycle delay in Chinese hamster ovary cells. No indications for differences in mutagenic activity were found between concentrates prepared from the urine of smokers, non-smokers or patients with alcoholic cirrhosis of the liver. These effects were obtained without metabolic activation in vitro. Experiments including variations in preparative procedures indicate that a quick saturation of the resin by non-polar compounds from human urine may lead to an underestimation of the amount of mutagenic substances in a given urine sample.
This paper describes a technique of mandibular reconstruction using the sternal skin and the outer table of the sternum transferred as a compound osteo-musculocutaneous flap based on the pectoralis major muscle. The technique has been used for immediate reconstruction at the time of cancer ablation but it can equally well be used as a delayed reconstructive procedure.
The meiotic findings in four oligochiasmatic males are described. Radiation studies on the somatic cells of three of them failed to provide evidence for a reduced facility to repair DNA which might also have accounted for the observed failure of chiasma formation at meiosis. The data support the idea that the 'low chiasma count' condition in sterile men is of mixed aetiology.
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