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.
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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.
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Life-threatening complications of cancer therapy often involve multiple organ systems and offer a therapeutic challenge which can be met with efficiency and success by concentrating personnel and equipment in a facility devoted to these problems. Three years ago, an Intensive Care Unit was created at Memorial Cancer Center to offer such patients the benefit of highly skilled nursing, advanced monitoring and supportive techniques, and full-time attendance by physicians and surgeons with a particular interest in Critical Care Medicine. Since then, 1035 patients have been admitted to the eight-bed unit with a mortality rate of 22.3%, which compares favorably with those reported from other institutions. Analysis of this experience has revealed that an average of 16% of those who survived their acute problems after considerable effort and expense, subsequently died of their underlying disease within 2 months. This experience has suggested the need for prognostic criteria to facilitate recognition of those patients for whom intensive supportive measures offer a reasonable chance of worthwhile palliation.
Spleen cells from BDIX-rats bearing either GVlAl-tumor (a syngeneic mixed glioma) or NVlAc-tumor (a cloned syngeneic neurinoma of the peripheral nervous system) were cytotoxic to both tumor cells in vitro. However, the tumors displayed individually distinct antigenic specificities by in vivo rejection tests. Their in vitro cross-reactivity disappeared when a particular subpopulation of the spleen cells was used. The procedure of lymphocyte purification included three consecutive steps: treatment with carbonyl iron and magnetism, passage through a nylon wool column, and finally removal of complement receptor-bearing cells present in the colum-excluded population. Cross-reactivity between the syngeneic tumors persisted after the first two steps of lymphocyte purification. In contrast, specific cytotoxic reactions were observed against each individual tumor subsequent to the removal of the remaining C3 receptor-positive but surface Ig-negative cells. While killer cells were present in normal spleen-cell populations, these were almost completely eliminated by passage through the nylon wool column.
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