Biomedical subjects
Publications and source records attributed to D Silverman.
We previously reported that long-term truck drivers and mechanics in the Teamsters Union had higher lung cancer risks than Teamsters outside the trucking industry. We now summarize results from an industrial hygiene survey of current exposures to diesel exhaust in the trucking industry, and relate these to our prior results pertaining to lung cancer risk.
Although it is acknowledged that counselling can be an important factor in behaviour change, we lack information on how HIV counselling works in practice. Research is reported based on transcriptions of audio-tapes of counselling drawn from seven hospital centres in England and the USA. It is shown that communication occurs in the context of three different formats. Certain formats and conversational strategies used by counsellors produce far greater patient participation. Such participation may hold out the prospect of greater behavioural change than simply listening to information and advice.
Cancer incidence was ascertained in a population-based cohort of 51,008 patients in Uppsala, Sweden, who were given a discharge diagnosis of diabetes mellitus during 1965-83. Complete follow-up through 1984 with exclusion of the first year of observation showed that the observed number of cancers in females (1,294) was eight percent higher than expected (relative risk [RR] = 1.1, 95 percent confidence interval = 1.0-1.1), whereas in males the observed number (1,123) was close to the expected (RR = 1.0, 0.9-1.1). Significantly increased risks of pancreatic (RR = 1.4, 1.2-1.7), primary liver (RR = 1.5, 1.2-1.7), and endometrial (RR = 1.5, 1.2-1.8) cancers and a lower than expected number of prostatic cancers (RR = 0.7, 0.7-0.9) were found in this cohort of diabetic patients. The excess risk of pancreatic cancer was similar in females and males and evident both during one through four years (RR = 1.7, 1.4-2.1) and five through nine years (RR = 1.3, 0.9-1.7) of follow-up, but not thereafter. A similar pattern was found for primary liver cancer, but the RRs were generally higher in males than in females.
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Antibodies to Rickettsia rickettsii erythrocyte-sensitizing substance (ESS) were raised in rabbits by using a derivatized ESS. The resulting antibodies reacted with R. rickettsii and cross-reacted with Rickettsia conorii, a member of the spotted fever group rickettsiae, but did not react with Rickettsia typhi, a member of the typhus group rickettsiae, Legionella bozemanii, or Proteus vulgaris OX19 or OX2. Immunoblot analysis indicated that ESS was present in more than one fraction and that the major haptenic fraction was proteinase resistant. Immunoelectron microscopy indicated that the antibodies to R. rickettsii were specific to components located on the cell surface and intracellularly to components between the cell wall and cytoplasmic membrane.
The relationship between p-xylene's effects on microsomal membranes, cytochrome P-450, and benzo[a]pyrene (BaP) metabolism was studied. p-Xylene (1 g/kg, ip, 1 h) inhibited 3-hydroxy BaP (3-OH) formation and decreased arylhydrocarbon hydroxylase (AHH) activity approximately 40% in rat lung microsomes. BaP dihydrodiol and quinone formation were unchanged by p-xylene administration. Cytochrome P-450 was below the limit of detection in lung microsomes from p-xylene-treated rats. Total phospholipid (PL) and phosphatidylcholine (PC) in microsomal membranes were decreased 28% and 17%, respectively. Cholesterol (CL), phosphatidylethanolamine (PE), phosphatidylserine (PS), phosphatidylinositol (PI), and sphingomyelin (SM) were unchanged. The net activity of enzymes involved in the synthesis of PC, phosphatidylethanolamine-N-methyltransferase I and II (PMT I and PMT II), was slightly elevated by p-xylene. PL/CL and PC/PE ratios, indicators of membrane fluidity, were decreased 34% and 13%, respectively, in microsomes from p-xylene-treated rats. Analysis of fluidity by fluorescence polarization showed that the actual fluidity of treated microsomes was slightly decreased (5%) as compared to controls. The decrease in P-450, PL, and PC is considered to contribute to the inhibition of BaP metabolism.
The authors describe a continuum of collaborative interdisciplinary professional practice which can be used for teaching students in health care settings. Choices about the nature of interdisciplinary practice can be made not only on the imperatives of patient care but also on the interpersonal characteristics of health care providers as well as their needs for professional autonomy. This model can enable students to make clear career decisions about the types of interdisciplinary practice best suited to their interpersonal style and professional needs.
With the use of data from the 8,764 subjects in the National Bladder Cancer Study, the separate contribution of various aspects of a person's cigarette smoking history to his increased risk of bladder cancer was estimated. These estimates have not been previously available, owing to the smaller sizes of earlier studies. Our data indicated that people who have only smoked unfiltered cigarettes have higher risks than those who have only smoked filtered cigarettes but that people who have switched from unfiltered to filtered have experienced no reduction in risk. Our data also indicated that smoking cessation substantially reduced the risk. The former smoker appeared to benefit both because he stopped adding to the burden of irreversible damage and because he ceased being exposed to some reversible hazard. Thus the former smoker had a lower risk than the current smoker even though they had smoked the same number of cigarettes daily for the same number of years, but the former smoker's risk remained higher than the risk of a person who never smoked. Our data suggest that one-half of the bladder cancer occurring among men in the United States and one-third of that among women is caused by cigarette smoking.
We have used pulse-chase techniques to study the synthesis, intracellular modification, and secretion of human apolipoprotein E by cultures of HepG2 cells and peripheral blood human monocyte macrophages. We have found that modified apoE isoproteins are detectable intracellularly after 14 min of pulse, and their relative concentration increases linearly over a 2-h pulse-chase period. At the same time, the relative concentration of unmodified apoE decreases. All the major modified apoE isoproteins appear simultaneously, and they correspond to the sialo apoE forms apooEs2, apoEs4, and apoEs6. ApoE secretion is first detected after a 30-min pulse. Secreted apoE consists of 92% of the same sialated apoE forms observed intracellularly. ApoE sialation and secretion were not affected by treatment of the HepG2 cultures with tunicamycin, whereas monensin inhibited both the intracellular sialation and secretion of this protein. These findings suggest that apoE is secreted in the form of three major isoproteins generated by intracellular modification of this protein with one or more O-linked oligosaccharide chains containing sialic acid.
Twelve-hundred consultations at a paediatric cardiology outpatient clinic were observed and tape-recorded. A random sample of 102 consultations was selected and an analysis made of the demand for information by parents and the extent to which this was met. Statistically significant differences in numbers of questions asked were found related to stage of treatment, seriousness of condition and outcome of consultation. Most questions were asked either when definitive information was available (i.e. following cardiac catheterisation) or when active intervention was contemplated (i.e. catheterisation or surgery). Contrary to parents' accounts in subsequent home interviews, the number of questions they ask is unrelated to the length of the consultation. Similarly the presence of many medical staff at the consultation, was positively correlated with the number of parents' questions. In general there was a good fit between parental participation and those occasions where most was at stake except at the first outpatient appointment. This was regarded, at least in retrospect, as unsatisfactory by many parents irrespective of its length or content. We suggest that an additional but optional "pre-admission" outpatient appointment where the family visit the wards prior to the child's admission to hospital may help parents cope with their anxieties.
We conducted a case-control study in ten areas of the United States in which a total of 2,982 bladder cancer patients and 5,782 population controls were interviewed. We employed a variety of existing and new techniques to reduce bias and to monitor the quality of data collected. We review here many of the design elements and field methods that can be generally applied in epidemiologic studies, particularly multi-center interview studies, and explain the reasons for our selection of the methods, instruments, and procedures used.
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Sixteen patients with serious Gram-negative bacillary infections were treated with intravenous ceftazidime, 2 g every 8 h. The majority of patients had bacteraemia or pneumonitis or both. Ten patients were cured and six improved. Seven of ten patients infected with Pseudomonas aeruginosa were cured, and three improved. No adverse reactions occurred. Four strains of Ps. aeruginosa became resistant to ceftazidime in patients who were cured or improved clinically. Ceftazidime is effective as single drug therapy for serious Gram-negative infections, including those due to Ps. aeruginosa.
The authors assessed the clinical thinking of medical students before, during, and after their first extensive in-hospital learning experience and exposure to physician role models. They found that more than 90% of the students' requests for additional data in response to videotaped simulated patient interviews were for biologic information; approximately 66% of all respondents in six separate trials failed to request a single psychological or social item concerning the patient. The authors discuss the pervasiveness of the biomedical rather than the biopsychosocial mentality and its implications for medical education as well as clinical teaching, decision making, and practice.
There is a continuous search for more reliable, locally non-invasive tests for prediction of leg viability and for the selection of amputation levels in dysvascular lower limbs. Refinement of the dermofluorometer by addition of a shielded probe and fibreoptic bundles has reduced the bulk of the instrument and permitted rapid testing. Excitation light is carried to the tissues and emitted fluorescence is returned to a photo multiplier. The Index of Fluorescein Uptake is 20-30 units in control areas. Healing is constant above 15 units, inconstant from 5 to 15 units, and absent below 5 units. Reliability has been virtually 10% in preliminary tests.
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