Biomedical subjects
Publications and source records attributed to R E Thomas.
The effectiveness of screening and organisational strategies to improve the recognition and management of depression in primary care published in a recent issue of Effective Health Care is reviewed.
The logging industry remains one of the most hazardous in the nation. Despite more stringent safety regulations and improvements in equipment safety features, the rate of logging fatalities has decreased at a much lower rate than the decrease in the rate of illnesses and injuries in the same occupation. The objective of this research was to identify and assess the hazards associated with logging operations in the Southeast region of the U.S. and propose interventions, taking into consideration the fact that, currently, most operations in the region are fully mechanized. Five logging crews in East Central Alabama participated in the study and were observed repeatedly during their normal operations. Researchers observed loggers engaging in multiple unsafe behaviors, but none of those led to an injury. The incidence of unsafe behaviors may be due in part to a lack of awareness of the hazards. Results indicate that Occupational Safety and Health Administration (OSHA) regulations appear to have little influence on logging safety. Loggers believe that most safety training recommendations are difficult to implement and negatively impact productivity. Thus, there seem to be fundamental drawbacks in the logging industry regarding effective delivery of safety training to loggers. The present study was a joint venture by the Industrial and Systems Engineering and Psychology departments of Auburn University, with support from the United States Forest Service (USFS).
OBJECTIVE: To present for family physicians without access to a travel clinic and the Internet the questions to ask about the medical history and itinerary of their patients traveling abroad. To suggest ways to identify and advise high-risk patients. QUALITY OF EVIDENCE: MEDLINE searches from 1990 to November 1998 located 51 articles on travel and diabetes, 37 on travel and chronic obstructive pulmonary disease (COPD), 63 on travel and heart disease, 192 on travel and pregnancy, and 298 on travel with infants or children. Additional searches were undertaken in September 1999. The quality of evidence in most articles is level III (expert opinion). There are no randomized controlled trials of the best advice for family physicians to give travelers. MAIN MESSAGE: A history should include countries to be visited, planned activities, previous tropical travel, medical history, vaccination status, whether children are traveling, pregnancy status, and patients' opinions of the risks and precautions needed. Detailed advice should be given to reduce risks. The main causes of mortality abroad are existing cardiovascular conditions and accidents. High-risk conditions to be identified in travelers are cardiovascular illness, COPD, diabetes, immunodeficiency, pregnancy, and traveling with children. CONCLUSIONS: Patients with cardiovascular illness or COPD should be advised to avoid too much exertion while traveling. Detailed instruction should be given to diabetic patients on how to maintain stable glucose levels, to pregnant women on avoiding malarial infection, and to parents on protecting their children from infections and accidents.
OBJECTIVE: To provide, for family physicians without access to a travel clinic, evidence-based recommendations on vaccinating infants and children, adults, pregnant women, and immunocompromised patients traveling to non-Western countries. QUALITY OF EVIDENCE: Searches were undertaken of MEDLINE from 1990 to November 1998 (372 articles); the Cochrane Collaboration Library; publications of the National Action Committee on Immunization and the Committee to Advise on Tropical Medicine and Travel in Canada Communicable Disease Reports; the Canadian Immunization Guide; and Laboratory Centre for Disease Control, United States Centres for Disease Control, and World Health Organization websites. Evidence-based statements, randomized controlled trials, systematic reviews, and meta-analyses were selected. Vaccination recommendations are based on this evidence. MAIN MESSAGE: Physicians should complete vaccination schedules for children whose primary series is incomplete and vaccinate unvaccinated adults. Hepatitis A is widespread, and travelers to areas where it is endemic should be vaccinated. The elderly should be vaccinated against influenza and pneumococcal disease. Pregnant women should receive vaccines appropriate to their trimester. Immunocompromised patients should be vaccinated, but BCG and live vaccines are contraindicated. Travelers to areas where meningitis, typhoid, cholera, Japanese encephalitis, and rabies are endemic should be vaccinated if they are likely to be exposed. Those traveling to areas where tuberculosis is endemic should take precautions and should have skin tests before traveling and 2 to 4 months after return. CONCLUSIONS: Family physicians can administer all necessary vaccinations. They can advise pregnant women and immunocompromised people about the balance of risk of disease and benefits of vaccination.
OBJECTIVE: To provide evidence-based recommendations for family physicians advising travelers on how to reduce their risk of malaria and dengue fever. QUALITY OF EVIDENCE: A search of MEDLINE from 1990 to November 1998 found 671 articles; randomized controlled trials and systematic reviews were sought. The Cochrane Collaboration was searched for studies relevant to family physicians; meta-analyses of impregnating bed nets with permethrin were found. Health Canada's evidence-based publications were searched; 10 recommendations based on at least one well-conducted randomized trial were found. MAIN MESSAGE: Good evidence-based advice about the efficacy of mefloquine in chloroquine-resistant areas and for pregnant women and children is available, as is advice on the effectiveness of permethrin-impregnated bed nets. CONCLUSIONS: Family physicians can use evidence-based recommendations to advise their patients on how to prevent malaria. The ways in which patients neglect malaria precautions are well-known. For prevention of both malaria and dengue fever, family physicians should counsel their patients to reduce the risk of being bitten by insects.
OBJECTIVE: To present evidence-based recommendations on traveling abroad safely so family physicians can advise travelers on how to reduce risk of accidents, diarrhea, and sexually transmitted diseases (STDs) and how to treat diarrhea themselves if medical care is unavailable. QUALITY OF EVIDENCE: A MEDLINE search from 1990 to November 1998 found 163 articles on travel and accidents, 504 on travel and diarrhea, and 42 on travel and STDs. Titles and abstracts were reviewed, and randomized controlled trials (RCTs) and systematic reviews were sought. The Cochrane Collaboration database of systematic reviews and meta-analyses was searched for studies relevant to family physicians. MAIN MESSAGE: For preventing diarrhea, RCTs demonstrate that bismuth subsalicylate, doxycycline, ciprofloxacin, and trimethoprim-sulfamethoxazole are useful prophylactics. Once travelers have diarrhea, RCTs show that loperamide and zaldaride reduce symptoms and duration; quinolones, ciprofloxacin, norfloxacin, and oral aztreonam reduce abdominal symptoms and time to last liquid stool by several days; azithromycin is effective in treatment of ciprofloxacin-resistant Campylobacter, and trimethoprim-sulfamethoxazole is effective in treating cyclospora. There are no RCTs of preventing accidents and STDs abroad. Health Canada has issued a statement summarizing the risks of acquiring STDs abroad. CONCLUSION: Family physicians can advise their patients on how to reduce risk of travelers' diarrhea and how to treat it themselves on holiday. There is expert advice on how to reduce risk of STDs.
Mussels, Mytilus trossulus, were sampled in 1996 from beaches in Prince William Sound (PWS) which contained residual oil resulting from the Exxon Valdez oil spill of March 1989, and from one beach which had been lightly oiled in 1989, but contained no residual oil in 1996. The latter mussels served as un-oiled references. Mussels were also collected from Tee Harbor, Southeast Alaska, to be used as an additional reference group. Where the size of the individuals in the resident population would permit, two size groups were sampled, 32-35 and 18-20 mm in length. Polynuclear aromatic hydrocarbon (PAH) concentrations in mussel tissue, and air survival time were determined for each group of mussels. Total PAH concentrations were significantly greater in tissue of mussels from oiled beds (0.6-2.0 micrograms g-1) than from references (0.01-0.12 microgram g-1) (P < 0.01). Oil-exposed mussels had significantly lower LT50 values (P < 0.05) for air survival than reference groups. Tolerance of small mussels to air exposure was significantly greater (P < 0.01) than large mussels in both the unoiled reference and oil exposed groups.
Mussels, Mytilus trossulus, were sampled in 1992 and 1993 from beaches in Prince William Sound that had been oiled by the Exxon Valdez spill of March, 1989. At some of the oiled beaches, mussels were collected from beds overlying oiled sediments, and from bedrock adjacent to these beds. Mussels were also collected from beaches within the Sound that had not been impacted by the spill. Polynuclear aromatic hydrocarbon (PAH) concentrations in mussel tissue, physiological responses (byssal thread production, condition index, clearance rate, and glycogen content), were determined for each group of mussels. Total PAH concentrations in mussel tissue ranged from 0 to 6 micrograms g-1, and were significantly greater in mussels from oiled beds than those from reference beds. No significant differences were noted in byssal thread production, condition index, clearance rate, or glycogen content between oiled sample sites and reference sites. The lack of physiological response was surprising because mussels in this study were chronically exposed to PAH for 3-4 years, and none of the physiological responses measured appeared to be affected by that exposure. The lack of a physiological response suggests that chronically exposed mussels may develop a physiological tolerance to PAH, but we recognize that these measures may not have been sensitive enough to discriminate response from background noise.
A sapphyrin-modified silica gel support for use in high-performance liquid chromatography was prepared by attaching a sapphyrin monocarboxylic acid to aminopropyl silica gel through an amide bond. The anion retention characteristics of this modified silica gel were tested by exploring the extent to which a specific anion in the mobile phase would act to affect the rate at which AMP was eluted from an HPLC column containing this functionalized stationary phase. In general, it was found that phosphate and arsenate anions were more effective as eluents than carboxylic acids and halides, a result that was interpreted in terms of these former species binding better to sapphyrin (and hence being more effective in terms of displacing AMP) than other anions tested. Support for the contention that phosphate anions will bind to sapphyrin subunits covalently tethered to the silica gel came from solid state 31P NMR spectroscopic analyses. These revealed that the 31P nucleus undergoes a 5 ppm upfield shift, relative to control, when allowed to interact with the sapphyrin-containing support.
We have performed a systematic variability study of polyclonal antibody catalysis by using five rabbits immunized with the same hapten. Important results from this work are the following. (1) Similarities were observed in the catalytic polyclonal antibodies derived from all five rabbits. Four of the five rabbits produced polyclonal samples that were nearly the same in terms of catalytic activity, whereas the fifth rabbit, designated as rabbit 2, displayed a somewhat higher level of catalytic activity. The catalytic activities (as kcat/kuncat) of these polyclonal samples were similar to that from the best murine monoclonal antibody that had been previously elicited by the same hapten. (2) Titre was not an accurate indicator of polyclonal antibody catalytic activity. (3) A mathematical analysis to describe a distribution of Michaelis-Menten catalysts was performed to help interpret our results. (4) Kinetic analysis indicated that the binding parameters of the different samples were remarkably homogeneous, because one or two components were all that were required to fit the on-rate and off-rate data satisfactorily. Interestingly, the most active catalytic polyclonal sample, that from rabbit 2, displayed the slowest off-rate (so slow it could not be measured) and thus the highest overall affinity. (5) Catalytic analysis of eluted fractions of antibody from a substrate column indicated that each polyclonal sample was also relatively homogeneous in terms of catalytic parameters. The main conclusion of our study is that for this hapten-animal system, the overall catalytic immune response is relatively consistent at two levels. Consistent catalytic activity was observed between the polyclonal samples elicited in the different animals, and the elicited hapten-specific polyclonal antibodies were relatively homogeneous in terms of binding and catalytic parameters within each immunized animal. The observed similarities of the catalytic activity in the different animals is surprising, because the immune response is based on specific binding of antibodies to hapten. There is no known selective pressure to maintain consistent levels of catalytic activity. Our results can therefore be interpreted as providing evidence that for this hapten there is a fixed relationship between hapten structure and catalytic activity and/or consistent genetic factors that dominate the catalytic immune response.
If bone mineral density (BMD) screening is to achieve the aim of preventing the complications of osteoporosis, women with low BMD measurements must learn that they are at risk, and women at risk must know about and be willing to adopt and persist with measures that can prevent osteoporosis. In this paper we present the results of a randomized controlled trial designed to examine whether disclosing the results of a BMD scan directly to women, as well as through their general practitioners (GPs), improves their knowledge of their bone density results without adverse psychological sequelae. Direct disclosure resulted in 19% (59% vs 40%; 95% CI for difference in proportions: 9.8% to 27.8%) more women being aware of their BMD status at the spine and 22% (58% vs 36%; 95% CI for difference: 12.2% to 29.8%) at the hip. These differences were observed irrespective of risk status. There was no significant difference in anxiety levels between the randomized groups. We conclude, therefore, that direct disclosure of BMD results to women, as well as to their GPs, leads to increased knowledge of BMD status without increasing anxiety, and that BMD measurement services should consider informing women routinely of their results directly as well as through their GPs.
OBJECTIVE: This study evaluated the effect of a heparin-bonded pulmonary artery catheter (PAC) on the activated coagulation time (ACT). DESIGN: A prospective, controlled comparison. SETTING: A tertiary care university hospital. PARTICIPANTS: Adult cardiac surgery patients. INTERVENTIONS: Celite ACTs were measured from arterial and central venous blood samples before and after the insertion of a heparin-bonded PAC. Thromboelastograms were also obtained from central venous blood samples before and 2 minutes after PAC insertion. MEASUREMENTS AND MAIN RESULTS: There was no significant difference between the sample sites before PAC insertion. After PAC insertion, the central venous ACTs were significantly increased compared with the corresponding arterial measurements at 2, 5, 10, and 20 minutes (p < 0.005, analysis of variance [ANOVA] for repeated measures, Fisher's protected least significant difference [PLSD]). The 2-minute post-PAC reaction time from the central venous blood sample was greater than 60 minutes in all cases. CONCLUSION: The heparin-bonded PAC was associated with a localized, time-dependent alteration in the ACT. Whenever possible, blood samples for baseline ACT measurements should be obtained from an arterial catheter to minimize the anticoagulant effects from the PAC.
Passage of ingested cat immunoglobulin G (IgG) into the hemocoel of cat fleas, Ctenocephalides felis (Bouché), was examined using antibody capture enzyme-linked immunosorbent assays (ELISA) and Western blotting. Fleas were fed heparinized cat blood via membrane feeders. Cat IgG was present in the hemolymph of engorged female fleas 1 h after ingestion at an estimated quantity of 35 +/- 14 micrograms/ml. The prevalence of fleas with demonstrable cat IgG in their hemolymph 1 h after feeding was 100% for both female and male fleas. Following a single blood meal, cat IgG was present in the hemolymph of all 15 fleas tested 1 h after ingestion but dissipated below detectable levels in 10 of 20 fleas examined 3 h after ingestion, and was detectable in only 1 of 10 fleas examined 18 h after ingestion. However, when fleas were provided with continual access to blood over a 72-h period, IgG content in hemolymph, as measured in excised, triturated legs of individual fleas, remained fairly constant (3-16 pg IgG per sample). Flea feeding studies using specific antisera indicated that IgG in flea hemolymph retained its binding activity, and that at least a portion of the IgG was intact. Passage of ingested host antibody from gut into hemocoel is a prerequisite for the possible development of antiflea vaccines that target antigens outside of the flea midgut lumen (e.g., key components of the flea endocrine system controlling oogenesis).
OBJECTIVE: To examine the relationship between benzodiazepine (BZD) use and motor vehicle accidents (MVAs). DATA SOURCES: MEDLINE was searched from 1980 to 1997 using the key words traffic accidents or motor vehicle accidents and benzodiazepines (and alternative terms and outcomes) in English, German, French, or Italian. STUDY SELECTION: Case-control studies of BZDs and MVAs; police or emergency studies of BZD use among travelers; driving tests with subjects taking BZDs. Outcomes were impaired driving, accidents; mortality; postaccident medical attention, emergency ward care, or hospitalization. Quality criteria were whether all driving BZD users and non-users had an equal chance of entering the study; whether medication dosage and timing were ascertained; whether all kilometres driven by BZD users and non-users were studied; whether all types of accidents were ascertained; and whether medical conditions were controlled for. SYNTHESIS: In case-control studies, the odds ratios for mortality and emergency medical treatment ranged from 1.45 to 2.4 in relation to time of use and quantity of drug taken. In police and emergency ward studies, BZD use was a factor in 1% to 65% of accidents (usually 5% to 10%). In two studies where subjects had blood alcohol concentrations less than the legal limit, BZDs were found in 43% and 65% of subjects. In one study with controls, 5% of drivers and 2% of controls in accidents had used BZDs. CONCLUSIONS: Case-control studies suggest using BZDs approximately doubles the risk of motor vehicle accidents. The risk for drivers older than 65 of being involved in reported motor vehicle collisions is higher when they take longer-acting and larger quantities of BZDs.
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The effects of pituitary-derived melanocortin peptides are primarily attributed to ACTH-mediated adrenocortical glucocorticoid production. Identification of a widely distributed receptor for ACTH/MSH peptides, the melanocortin-5 receptor (MC5-R), suggested non-steroidally mediated systemic effects of these peptides. Targeted disruption of the MC5-R produced mice with a severe defect in water repulsion and thermoregulation due to decreased production of sebaceous lipids. High levels of MC5-R was found in multiple exocrine tissues, including Harderian, preputial, lacrimal, and sebaceous glands, and was also shown to be required for production and stress-regulated synthesis of porphyrins by the Harderian gland and ACTH/MSH-regulated protein secretion by the lacrimal gland. These data show a requirement for the MC5-R in multiple exocrine glands for the production of numerous products, indicative of a coordinated system for regulation of exocrine gland function by melanocortin peptides.
BACKGROUND: Screening perimenopausal women for low bone density has yet to be tested in a randomized trial. The effect of screening on the use of hormone replacement therapy (HRT) and the subsequent quality of life in these women is unknown. The purpose of this study was to assess the effect of a screening program on HRT use of quality of life. METHODS: A random sample of women aged 45 to 54 years and living within 32 km of Aberdeen, Scotland, was selected from the community health index. Subjects were further randomized to screening or no screening using the design of Zelen. Two years after randomization, a questionnaire follow-up was mailed to both groups to assess HRT use and quality-of-life scores. RESULTS: Use of HRT was higher in the screened group (30% vs 24%; difference, 6%; 95% confidence interval, 1%-11%; P = .02). A multivariate analysis indicated that the odds of using HRT for a screened woman whose measurement for bone mineral density was in the lowest quartile was 2.54 (95% confidence interval, 1.74-3.71) greater than that of an unscreened woman. Screening and subsequent HRT use did not have any detectable effects-positive or adverse-on women's quality of life. CONCLUSION: Screening for low bone density significantly increases the use of HRT in this population but without any immediate adverse or positive effects on quality of life.