Exclusion limits on the WIMP-nucleon cross section from the cryogenic dark matter search.

The Cryogenic Dark Matter Search (CDMS) employs Ge and Si detectors to search for weakly interacting massive particles (WIMPs) via their elastic-scattering interactions with nuclei while discriminating against interactions of background particles. CDMS data, accounting for the neutron background, give limits on the spin-independent WIMP-nucleon elastic-scattering cross section that exclude unexplored parameter space above 10 GeV/c2 WIMP mass and, at >75% C.L., the entire 3sigma allowed region for the WIMP signal reported by the DAMA experiment.

Binding of lithium and boron to human plasma proteins.

The binding of lithium and boron, at normal physiological levels, to plasma proteins has been investigated by the techniques of precipitation with ethyl alcohol and gel chromatography. Assays of lithium and boron were made by thermal neutron activation and mass spectrometric assay of 3He and 4He. Results of alcohol precipitation experiments for plasma from two apparently healthy donors showed that 13+/-4% and 16+/-3% of the lithium in plasma is protein bound, but essentially no boron is bound under the conditions used. We believe that because of denaturation of proteins which occurs during alcohol precipitation, these percentages represent lithium and boron tightly bound to protein molecules. The results of the gel-chromatography experiment, on the other hand, showed that lithium and boron are bound to a wide range of plasma proteins, from low (approximately 60,000 amu) to high (approximately 1,000,000 amu) molecular weights, and to very low- (approximately 6000 amu) molecular-weight ligands. Although a clear identification of the specific proteins which bind lithium and boron cannot be made at present, some possibilities can be suggested.

Regulation of lithium and boron levels in normal human blood: environmental and genetic considerations.

Blood lithium levels may be both genetically and environmentally regulated. The genetic component is evidenced mainly from studies in twins who were either normal or had a manic-depressive disorder. An environmental contribution is adduced from the relationship between the blood lithium level and the amount of the element ingested. No such information is available for boron, another element present in ultra trace amounts in human blood. Unusually high levels of lithium and boron in the waters of northern Chile offer an opportunity to study the genetic and environmental regulation of these elements in the blood of healthy subjects. Samples of blood (n = 40) and water (n = 47) were collected at seven locations in the province of Tarapaca. Most of the healthy subjects were Aymara who had been resident in the respective communities for at least 3 years. The samples were transported to Canada and then freeze-dried. Neutron irradiation was performed in a highly thermalized flux to induce the reactions 6Li (n, alpha) t and 10B (n,7Li) alpha. Assays of 6Li and 10B were conducted in a static mass spectrometer by measurement, respectively, of 3He, produced from decay of tritium, and 4He from alpha-particles. Lithium concentrations in water and blood exhibited a linear relationship, as did the boron concentrations in these fluids. Because some of the individual subjects (n = 15) were first-degree relatives, a genetic component to the regulation of blood levels was explored. The variance in blood levels of lithium and boron was significantly greater between than within families (p < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Improving the quality of community health surveys and community health promotion campaigns by feedback from the community: experience from the Wallsend community and health project.

A lifestyle and health risk survey was conducted in two socially disadvantaged Collector's Districts, as the basis for a health promotion intervention in one of the Districts. After community input into the planning, and local advance publicity, 395 people responded to the survey (a response rate of 39%). Three sources of community feedback were used: (i) reasons for refusal to participate; (ii) written comments solicited at a two-month follow-up; (iii) later, in-depth interviews with a subset of respondents. The data from this feedback related both to the process and outcomes of the survey; the latter included increased personal and community awareness of health, as well as lifestyle changes. The data are discussed in terms of their representativeness and the factors influencing participation, the implications of the low response rate, the stages of health behaviour change, and the potential conflict between scientific and human value-systems in community research.

The approaches to learning of students in a traditional and in an innovative problem-based medical school.

The way in which students approach their learning is dependent on a variety of factors including the characteristics of the departments and teaching to which they are exposed. These factors appear to influence whether the students adopt a surface, deep or strategic approach. In order to explore further the relationship between educational context and approach to learning, a comparison was made between students attending a traditional medical school and those attending a problem-based medical school. The results showed marked differences, with the problem-based school being higher on deep approach and lower on surface approach than the traditional school. This study provides one of the first pieces of evidence of a difference between students in the two types of medical school which can be directly attributed to the educational environment. Students in the problem-based school appear to have an approach to learning which more closely approximates the aims of most medical schools. The results provide support for the philosophies and strategies of the problem-based schools.

Student perceptions of the learning environment in a new medical school.

Students' perceptions of their learning environment in the Faculty of Medicine of the University of Newcastle were tested in 1979, in the second year of the school's existence, when the first two cohorts of students were surveyed. It was thought important to re-test those same cohorts in 1982, when they were in the later years of the curriculum, to see whether their perceptions had changed, and also to test the perceptions of subsequent cohorts of students (still in the earlier years of the course) to examine whether the favourable perceptions of the earlier cohorts were being maintained. Accordingly, this paper reports the results of a cross-sectional study undertaken on all five years of Newcastle medical students in 1982, and it compares their perceptions with those obtained 3 years earlier.

The elastic properties of a polyurethane arterial prosthesis.

The relationship between the mechanical properties of a fibrous polyurethane arterial prosthesis and the graft manufacturing process variables was studied from uniaxial tensile tests. A non-linear model was used to characterize the cylindrical elastic properties. Experiments on cylindrical segments were carried out to determine the constitutive constants and to assess the applicability of the model to the polyurethane graft. The compliance of 4 mm internal diameter grafts with various wall-thicknesses was predicted. The results were used to produce grafts with compliance matched to that of the carotid and femoral arteries.

Review of psychometric features of the Medical School Learning Environment Survey.

Growing concern over the stresses imposed on medical students by their undergraduate educational programme has led to a proliferation of surveys designed to measure students' global perceptions of the medical school as a learning environment. The present study aimed at a comprehensive analysis of the psychometric features of a recently-introduced questionnaire. Students at four Australian medical schools completed the Medical School Learning Environment Survey (Marshall, 1978). Data on the retest reliability, internal consistency and factorial validity of the MSLES are presented. Its potential usefulness for future evaluations within and between medical schools is discussed.

Undergraduate education in the cost-effective use of laboratory and radiological investigations in clinical decision-making.

This paper describes a strategy for helping students to learn about laboratory and radiological investigations in diagnosis and management, and to make decisions about the use of investigations, taking into account such features as safety, patient comfort and cost. Learning takes place through the use of a programmed text, in which students commit decisions to paper, and then receive feedback on the results of their decisions. Acceptability to students and teaching staff has been evaluated, and future developments of the strategy are outlined.

Cost and effectiveness of clinical investigation: the state of the art.

Clinical investigation by means of special technical tests has increased in clinical practice during recent years. Pressures causing this increase are said to include: rapid technological change making many more tests available, clinical uncertainty, peer pressure, greater patient awareness, and concern for diagnostic completeness. Cost factors do not appear to have influenced test-ordering behaviour to any large extent, and those ordering investigations are frequently ignorant of the cost of the test which they are ordering, both to the patient and the community. The relation of clinical investigational activity to quality of outcome of patient care remains largely unestablished. Studies of the possible modification of test-ordering behaviour through educational and institutional policy pressures are reviewed. A rational approach to investigating the effectiveness of techniques designed to encourage the more economic and effective use of investigations is presented in brief on the basis of this review of previously published work.

The anatomy of the peritoneum.

The author describes two educational strategies for helping students to understand the complex three-dimensional structure of the peritoneal cavity and the developmental changes by which that structure arises. The first strategy consists of a series of conducted circular tours round the peritoneal lining of the postnatal abdomen. The second is a demonstration of the developmental history of the placing of the gut and its peritoneum using a model.

Acute distal intestinal obstruction in gnotobiotic rats. Intestinal morphology and cell renewal.

1. Complete mechanical obstruction of the distal small intestine was produced in gnotobiotic rats. 72 h after the operation small intestinal morphology and epithelial cell renewal were investigated proximal and distal to the site of obstruction. 2. Proximal to the site of obstruction there were minor changes in villus height, base length and in villus cell number, a large increase in depth and diameter of the crypts and an approximately threefold increase in cell renewal. 3. Distal to the site of obstruction there were no differences between the intestines of rats with obstruction and controls. 4. The apparent lack of secretion by the goblet cells and the reduced number of intraepithelial leucocytes suggest that the barrier function of the small intestine is impaired in obstruction.

An experimental model for studies on the effects of food and digestive secretions on the digestive-absorptive capacity of rat small intestine.

At an average of 32 days after a modified Roux-en-y repositioning of rat small intestine, the mucosal mass, mucosal composition, in vivo absorption of galactose and the activity of maltase, sucrase and alkaline phosphatase were measured. In the gut segment with digestive secretions but without food (A) the only change was a decrease of sucrase activity which occurred most probably at the cellular level. In the gut segment with food and gastric juice and a reflux of digestive secretions (B) complex changes took place. An increase in mucosal mass was not accompanied by an increase in galactose absorption. There was a high increase of sucrase activity, a moderate increase of maltase activity and a tendency of the alkaline phosphatase activity to decrease. The changes (increase in mucosal mass and total enzyme activity, but no changes in activity at the cellular level) in the segment exposed to both digestive secretions and food (C) were compatible with a more proximal promotion of a distal gut segment.

The effects of age on mucosal morphology and epithelial cell production in rat small intestine.

Six groups of male Wistar rats were used, with mean weights of 29, 63, 97, 161, 249 and 399 g. Pieces of small intestine from three sites were examined after staining in bulk with the Feulgen reaction. Crypt/villus ratio (the number of crypts per villus) rose with age at all three sites, Villus height and crypt depth were measured on microdissected specimens. Villi in the proximal intestine were always taller than those distally. Proximal villi increased in height in successively older rats, except in the oldest group. Villi at the two distal sites tended to be tall in the youngest group of rats, but suffered a temporary reduction in height in the next two age groups. Crypt depth increased markedly within the first three age groups, and more slowly thereafter. Colchicine-metaphase accumulation rate was estimated from counts on microdissected intact crypts. The rate was low in the youngest group (8 cells/crypt/hour) but about 30 cells/crypt/hour in all other groups. After the changes during the early phase of rapid growth, no marked changes were seen during later life. The significance of these findings is discussed.

"Luminal nutrition" versus "functional work-load" as controllers of mucosal morphology and epithelial replacement in the rat small intestine.

Isotonic solutions of substrate were infused into surgically prepared sacs of upper small intestine in conscious unrestrained rats which fed normally via the gut-in-continuity. Infusion of glucose, galactose or sodium chloride all caused a local increase in villus height, while alpha-methyl glucoside and mannose had no effect. Glucose, galactose and alpha-methyl glucoside all stimulated a similar increase in counts of vincristine metaphases in microdissected crypts. although the absolute level of cell production was lower throughout the gut in glucose-infused rats. Sodium chloride infusion also caused a small stimulation of cell production locally, but a considerable increase in the uninfused gut-in-continuity. Mannose infusion had a variable effect on cell production. These results do not support "luminal nutrition" as a controller of epithelial replacement in the rat small intestine, and suggest that a mechanism based on the work-load of the epithelial may be more appropriate.

Analysis of the effects of food and of digestive secretions on the small intestine of the rat. 1. Mucosal morphology and epithelial replacement.

A modified Roux-en-Y repositioning of rat small intestine was performed so that the proximal segment of bowel (A) received only bile and pancreastic secretions, the second (B) received food direct from the stomach, and these two segments drained into a third (C). Four to five weeks after operation, cell production was assessed by injection of vincristine into operated, sham-operated and unoperated rats, and counts of blocked metaphases were made on isolated microdissected crypts. Villus height, crypt depth, and the number of crypts per villus (crypt/villus ratio) were also measured. Most of segment A showed no significant differences from sham-operated intestine, although the normal proximo-distal gradient of villus height was abolished. At the distal end (near the anastomosis with segments B and C), crypt depth and cell production were increased. The villus height gradient in segment B was also abolished, although crypt depth and cell production were significantly increased, especially at the proximal end. Crypt/villus ratio was also increased. Segment C showed all the characteristics of small bowel promoted to a more proximal position: increased villus height, crypt depth and cell production. Increased crypt/villus ratio was also observed. These results are discussed in terms of the role of food and of digestive secretions in the control of mucosal morphology and epithelial replacement.