Biomedical subjects
Publications and source records attributed to M Smith.
The method of operation of open-ended air-break receiver vessels was considered and a simple mathematical model proposed. The failure of this model to predict receiver performance as a result of turbulent mixing of the receiver contents was noted. Empirical results for the performance of stimulated receiver vessels are given and their application to the design and testing of actual receiver vessels discussed.
The advantages of active anti-pollution systems are discussed, in particular those depending on a high vacuum and narrow-bore pipework. The design requirements of a receiver for such a system are set out and the detailed design of such a receiver described. The performance of the unit is assessed with special regard to efficiency and safety.
In previous publications (Jones et al., 1977; Nordin et al., 1980) we have shown that menopausal symptoms respond well to 15 micrograms of ethinyl oestradiol and rather less well to 5 mg daily of norethisterone. We have not previously established whether even smaller doses of ethinyl oestradiol might be effective or whether combining this preparation with norethisterone might produce an additive effect. The present paper describes a trial designed to answer these questions.
Seven cis-dominant, constitutively expressed mutations of the normally glucose-repressible isozyme of alcohol dehydrogenase (ADHII) from the yeast Saccharomyces cerevisiae are caused by insertion of transposable elements from the Ty1 family in front of the ADHII structural gene (ADR2) (V. M. Williamson, E. T. Young, and M. Ciriacy, Cell 23:605-614, 1981). We cloned ADR2 with its associated Ty1 element from five S. cerevisiae strains carrying these mutations. Comparison of the Ty1 elements by heteroduplex studies and restriction enzyme analyses indicated that four were very similar; the fifth, although the same size as the others (about 5.6 kilobases), differed by the presence of two large substitutions of approximately 1 and 2 kilobases. The DNA sequences of the terminal direct repeats (deltas) were very homologous but not identical and were similar to previously reported Ty1 element direct repeats. We determined the 5'-flanking sequences of the ADR2 gene isolated from a wild-type strain and from five Ty1-associated mutations. The 5-base pair target sequence at the site of Ty1 insertion was present at both ends of each Ty1 element. The sites of insertion of the elements were all different and occurred from 125 to 210 base pairs in front of the coding region of ADR2. The 5' end of the major transcript as determined by S1 mapping was the same in wild-type cells and in Ty1-associated constitutive mutants and was approximately 54 base pairs upstream from the coding region. ADR2 transcripts were not detected when a solo delta sequence was present in the 5'-flanking region of this gene.
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We examined associations between physical fitness and risk factors for coronary heart disease in healthy women ages 18-65 years. Physical fitness was objectively determined by the duration of a maximal treadmill exercise test. Six physical fitness categories (very poor to superior), specific within 10-year age increments, were established. Mean risk factor levels varied across categories, but so did potential confounders such as age and weight. Multiple linear regression modeling was used to control for the effects of age, weight and year of exam on coronary risk factors. After adjustment, physical fitness was independently associated with triglycerides (p less than 0.001), high-density lipoprotein cholesterol (HDL-C) (p less than or equal to 0.001), total cholesterol/HDL-C ratio (p less than or equal to 0.001), blood pressure (p less than or equal to 0.001) and cigarette smoking (p less than or equal to 0.001).
Synthetic ovine corticotropin-releasing factor (CRF) is a 41-residue peptide with high potency and intrinsic activity to stimulate the secretion of ACTH and beta-endorphin-like immunoactivity (beta-End-LI) by cultured adenohypophysial corticotropic cells. The action of CRF in vitro can be potentiated by the weaker secretagogues, vasopressin, oxytocin, epinephrine, norepinephrine, and angiotensin II. CRF-mediated secretion of ACTH and beta-End-LI is noncompetitively inhibited by pretreatment of cells with glucocorticoids. Long term exposure of adenohypophysial cells to CRF results in an increase in total medium plus cell ACTH in the cultures, suggesting that CRF can enhance rates of ACTH synthesis as well as release. CRF also stimulates the secretion of beta-End-LI by corticotropic cells cultured from the neurointermediate lobe. Higher concentrations of CRF are required to stimulate secretion by this cell type than by anterior lobe corticotropic cells. These in vitro results are consistent with CRF playing a major physiological role in the neuroregulation of secretion by anterior lobe corticotropic cells, where the peptide may interact with other modulators.
Among 884 hospital patients with gastroenteritis, 36 (4.1%) were excreting Cryptosporidium oocysts in their stools; only 5 of the 36 patients were also excreting other enteropathogens, while none of 320 hospital patients without gastroenteritis were excreting Cryptosporidium oocysts. Children were more commonly infected with Cryptosporidium (4.8%) than were adults (1.6%). The prevalence of infection was higher (7%) during the summer period of February-May 1981 than in the remainder of the observation period to the beginning of June 1982 (1.9%). The most common clinical manifestation of gastroenteritis in Cryptosporidium-infected patients was diarrhea, lasting from 3 to over 14 days, accompanied by vomiting, anorexia, and abdominal pain. The results show that a small proportion of patients with gastroenteritis are infected with Cryptosporidium, and the importance of the infection needs to be examined.
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Rotavirus and enterotoxigenic Escherichia coli (ETEC) are enteropathogens each capable of inducing diarrhoea in some animal species and man. Unstressed young animals develop an age-related resistance to infection with either rotavirus or ETEC which differs for each animal species. The effects of experimental infection of calves, lambs, foals and piglets with rotavirus and ETEC given either alone or in combination, have been examined. In general, dual infections tended to lengthen the period of age susceptibility and increase the severity of gastroenteritis, compared to infection with either agent alone. ETEC caused little or no pathological changes in the small intestine while rotavirus induced moderate inflammatory, morphological and physiological changes including reduced activity of membrane-bound digestive enzymes. In dual infections, mucosal lesions were more severe than those seen after rotavirus infection and ETEC proliferation in the lumen of the small intestine was greater than in animals infected with ETEC alone. Two distinct mechanisms of diarrhoea, presumably, were involved; net fluid hypersecretion into the lumen of the gut mediated by ETEC enterotoxin(s), and brush border maldigestion and malabsorption which was caused by rotavirus infection of the small intestine.
A study of the associations between level of tooth lead, behaviour, intelligence and a variety of other psychological skills was carried out in the child population aged six to seven years in three London boroughs. Tooth lead was estimated from the chemical analysis of shed teeth donated by children. 2663 (62.4 per cent) of the eligible children donated teeth. A study of the total population was carried out to see if those who donated teeth were representative of that population. There were small but consistent and statistically significant differences--tooth-givers being of slightly higher intelligence and showing fewer behaviour problems. 403 children, selected on the basis of their tooth-lead levels and social class, were studied more intensively. They were classified into six pre-arranged groups--high, medium and low tooth-lead levels, with each lead group divided into two social groups, manual and non-manual. The parents of these children were intensively interviewed in their homes regarding parental interest and attitudes to education, family characteristics and relationships, the early history of the child and the child's physical environment. The intelligence of the mother was measured. The child was then studied in school using tests of intelligence, educational attainment and other cognitive tasks. Teachers and parents completed standardised behaviour questionnaires. The results showed that intelligence and other psychological measures were strongly related to social factors, especially social grouping. Lead level was linked to a variety of factors in the home, especially the level of cleanliness, and to a lesser extent, maternal smoking. There was no significant link between lead level and behaviour, though when rated by teachers, but not by parents, there were small and reasonably consistent non-significant tendencies for high-lead children to show more difficult behaviour. Before social factors were controlled for, there were significant differences between the lead groups in measures of intelligence and two other psychological tests, the children in the high-lead groups performing worse. Once a number of social factors had been taken into account, the differences between the three lead groups (high, medium and low) became small and statistically nonsignificant, although they remained in the same direction.(ABSTRACT TRUNCATED AT 400 WORDS)
While radiation has well-recognized effects on follicular cells of the thyroid gland, those on parafollicular C cells are not yet established. Low-dose radiation that has been proved to be nonablative and carcinogenic to follicular cells was administered to 8-week-old Long-Evans rats to study the changes in C cell number and function. Circulating calcitonin levels were significantly reduced in animals that had undergone radiation at age 24 months. Mean calcitonin values were 0.66 (+/- 0.20) ng/ml and 1.64 (+/- 0.59) ng/ml for control males and females compared with 0.14 (+/- 0.06) ng/ml and 0.11 (+/- 0.01) ng/ml for males (P less than 0.05) and females (P less than 0.001) that had undergone radiation, respectively. These levels correlated well with C cell population density in thyroid glands in the control group and in the group that had undergone radiation as evidenced by light microscopy. Routine hematoxylin and eosin staining showed C cell hyperplasia in 77% of control animals of both sexes compared with 4% in animals that had undergone radiation (P less than 0.005). Immunoperoxidase staining with an anticalcitonin antibody showed virtual absence of C cells in most animals that had undergone radiation compared with diffusely scattered cells in animals in the control group. Medullary carcinomas occurred in 14% of animals in the control group compared with 3% of animals that had undergone radiation (P less than 0.05). These data indicate that the radiation dosage that is carcinogenic to the follicular epithelium causes lethal injury to C cells and thus suggest that C cells are more sensitive to radiation than are follicular cells. This increased sensitivity could explain the virtual absence of C cells, decrease in calcitonin levels, and reduced numbers of medullary carcinomas in the animals that had undergone radiation.
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The subchondral bone pressure in the navicular bone of horses with navicular disease is compared with corresponding pressures in normal horses. An increased intraosseous pressure and a lengthened pressure drop time was demonstrated in patients with navicular disease, which indicates the existence of a venous stasis. Compared with similar investigations in humans with arthrosis it is concluded that navicular disease is a condition resembling arthrosis. The classical clinical symptoms are explained as an expression of resting pains. Treatments are suggested which theoretically can render the patient symptomless.
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