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Biomedical subjects

S Davis

Publications and source records attributed to S Davis.

At least 19 recordsLinked to original sources
PubMed1992

Random digit dialing: the potential effect on sample characteristics of the conversion of nonresidential telephone numbers.

This study examined the changes over time in the residential status of telephone numbers and the characteristics of households with telephone numbers that changed from nonresidential to residential. The authors determined the status in 1987 of all phone numbers (n = 9,107) that had been found to be nonresidential in six case-control studies conducted between 1979 and 1986 in Washington State. A telephone interview to obtain information on household characteristics was completed for 1,333 of the 1,901 phone numbers that had become residential by 1987. The interviews revealed that households with phone numbers that had previously been nonresidential differed from the general population with respect to household income, the age of household members, and the education of the head of the household. Data for the same area showed that the proportion of all phone numbers that were residential changed differentially according to the prefix (which roughly defines geographic area) during a 12-month period between 1987 and 1988, with some prefixes showing increases in residential phone numbers of more than 20%, while other prefixes decreased or stayed the same over the same period. We conclude that methods of random digit dialing that use two-stage designs or exclude previously dialed numbers may result in biased sampling unless changes over time are considered.

Adolescent↗
PubMed1992

Functional inhibition of hematopoietic and neurotrophic cytokines by blocking the interleukin 6 signal transducer gp130.

Functional pleiotropy and redundancy are characteristic features of cytokines. To understand the signaling mechanisms of such cytokines, we have proposed a two-chain interleukin (IL) 6 receptor model: IL-6 triggers the association of a ligand-binding chain (IL-6 receptor) and a nonbinding signal transducer (gp130) to form a high-affinity receptor complex, resulting in transmission of the signal by the cytoplasmic portion of gp130. This model would explain the functional redundancy of cytokines if we were to assume that gp130 interacts with several different receptor chains. Here we present data indicating that gp130 functions as a common signal transducer for IL-6, oncostatin M, leukemia inhibitory factor, and ciliary neurotrophic factor. We show that anti-gp130 monoclonal antibodies completely block the biological responses induced by all of these factors. Since leukemia inhibitory factor functions as a cholinergic differentiation factor in nerve cells, as does ciliary neurotrophic factor, these results suggest that gp130 may also play a role in the nervous system.

Animals↗
PubMed1992

Nutritional factors and the development of non-Hodgkin's lymphoma: a review of the evidence.

Lymphomas of the non-Hodgkin's type represent a heterogeneous group of tumors, probably comprised of groups of related diseases each with a distinct etiology. The epidemiology of non-Hodgkin's lymphoma is poorly characterized, and little is known about factors which increase a person's risk of developing one of these tumors. Available epidemiological evidence suggests the influence of a number of environmental factors. Although diet is potentially one of the most significant environmental factors that could be related to disease etiology, very little has been done to investigate the role of diet in the development of non-Hodgkin's lymphoma. In this paper, the existing epidemiological findings are reviewed, and the plausibility of an etiological association between dietary factors and non-Hodgkin's lymphoma is considered in the context of relevant animal research.

Animals↗
PubMed1992

Cot death.

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Humans↗
PubMed1992

CNTF and LIF act on neuronal cells via shared signaling pathways that involve the IL-6 signal transducing receptor component gp130.

Ciliary neurotrophic factor (CNTF) has a variety of actions within the nervous system. While some of the actions of leukemia inhibitory factor (LIF) on neurons resemble those of CNTF, LIF also has broad actions outside of the nervous system that in many cases mimic those of interleukin-6 (IL-6). Comparison of the tyrosine phosphorylations and gene activations induced by CNTF and LIF in neuron cell lines reveals that they are indistinguishable and also very similar to signaling events that characterize LIF and IL-6 responses in hematopoietic cells. We provide a basis for the overlapping actions of these three factors by demonstrating that the shared CNTF and LIF signaling pathways involve the IL-6 signal transducing receptor component gp130. Thus, the receptor system for CNTF is surprisingly unlike those used by the nerve growth factor family of neurotrophic factors, but is instead related to those used by a subclass of hematopoietic cytokines.

Animals↗
PubMed1992

Electric power, pineal function, and the risk of breast cancer.

Breast cancer is the leading cause of cancer death in women in the industrialized world, and the rates of breast cancer incidence are rising. Although risk is high in industrialized societies, it is low in nonindustrialized areas. The search for the causes of breast cancer has not yet yielded a convincing explanation for the geographic and temporal patterns in the occurrence of breast cancer. Generation of electric power is a hallmark of industrialization, and two products of electric power, light-at-night (LAN) and electromagnetic fields (EMF), may affect breast cancer risk. Exposure to either LAN or EMF can decrease production of melatonin by the pineal gland. Melatonin, in turn, has been shown to suppress mammary tumorigenesis in experimental animals. Moreover, recent epidemiological findings indicate an increased risk of breast cancer in workers occupationally exposed to EMF. On the basis of these considerations, it is proposed that the use of electrical power accounts, in part, for the higher risks of breast cancer in industrialized societies.

Animals↗
PubMed1992

A comparison of spinal and epidural anaesthesia for hip arthroplasty.

Spinal and epidural anaesthesia were compared in 65 patients undergoing hip arthroplasty, with regard to the degree of sensory and motor blockade, cardiovascular effects, operating conditions, the dose of propofol required to produce satisfactory hypnosis, and complications. Epidural anaesthesia was successful in 30 patients using an initial dose of 15 ml of 0.5% bupivacaine, and spinal anaesthesia in 32 patients, using 4 ml 0.5% isobaric bupivacaine. The two techniques were similar with regard to the level of sensory blockade (T8), degree of hypotension and perioperative haemorrhage. Differences occurred in the degree of motor blockade (mean Bromage score of 1 in the spinal group vs 3.86 in the epidural group) (P less than 0.05), time to achieve maximal cephalad spread (13 min in the spinal group vs 21 min in the epidural group) (P less than 0.05) and the dose of propofol required to produce adequate hypnosis (1.95 mg.kg-1.hr-1 in the spinal group vs 2.89 mg.kg-1.hr-1 in the epidural group) (P less than 0.05). Only seven patients required urethral catheterization in this spinal group compared with 14 in the epidural group (P less than 0.05). Spinal anaesthesia also proved advantageous by providing better operating conditions for the surgeon, with a lower incidence of patient movement.

Adolescent↗
PubMed1992

Impact of central venous catheter removal on the recurrence of catheter-related coagulase-negative staphylococcal bacteremia.

OBJECTIVE: To determine the impact of catheter management on the acute and long-term outcome of catheter-related coagulase-negative staphylococcal bacteremia. DESIGN: Retrospective surveillance of catheter-related sepsis using quantitative blood and catheter cultures. SETTING: University-affiliated tertiary cancer center. PATIENTS AND METHODS: Seventy patients with catheter-related coagulase-negative staphylococcal bacteremia were studied by retrospective chart review. The clinical characteristics of the patients and the management of the bacteremias were determined. The impact of immunosuppressive risk factors, antibiotic therapy, and catheter management on the recurrence of the bacteremia was investigated. RESULTS: Acute sepsis-related morbidity and mortality were not related to catheter management. However, during a 12-week followup period, the bacteremia recurred in 20% of the patients whose catheters remained in place, compared with only 3% of those whose catheters were removed (p less than .05). By multivariate analysis, patients whose catheters remained in place were 2.9 times more likely to experience a recurrence than those whose catheters were removed (odds ratio = 2.9, 95% confidence interval = 1.2-8.8, p = .03). All other potential risk factors were equally distributed between patients, with and without a recurrence. CONCLUSIONS: Although patients with catheter-related coagulase-negative staphylococcal bacteremia could be treated successfully while the catheter remains in place with the majority remaining free of recurrence, catheter retention results in a significantly higher risk for the recurrence of the bacteremia.

Adolescent↗
PubMed1992

A case-control study of occupational risk factors for laryngeal cancer.

To determine whether specific jobs and occupational exposures are associated with laryngeal cancer lifetime occupational histories from a population-based case-control study in western Washington were examined. The study included 235 cases diagnosed between September 1983 and February 1987, and 547 controls identified by random digit dialing. After controlling for alcohol use, cigarette smoking, age and education, significantly increased risks were found for painters in construction (odds ratio (OR)) = 2.8, (95% confidence interval (95% CI) 1.1-6.9), supervisors and miscellaneous mechanics (OR = 2.3, 95% CI 1.1-4.8), construction workers (OR = 3.4, 95% CI 1.4-8.1), metalworking and plastic working machine operators (OR = 2.6, 95% CI 1.3-4.9) and handlers, and equipment cleaners and labourers (OR = 1.5, 95% CI 1.0-2.2). Allowing for a 10 year induction and latent period did not have a consistent effect on the associations. Potential exposures to asbestos, chromium, nickel, formaldehyde, diesel fumes, and cutting oils were assessed by using a job exposure matrix developed for this study. Three measures of exposure were examined--namely, peak, duration, and an intensity weighted exposure score. No significantly raised risks were seen, although increased risk was suggested among those exposed long term to formaldehyde in jobs with the highest exposures.

Adult↗
PubMed1992

Assessing the "criminalization" of the mentally ill in Canada.

This paper is an overview of the conceptual and methodological problems encountered trying to assess the hypothesis that the mentally ill, as a consequence of deinstitutionalization, are being "criminalized". Generalizations are difficult to make, in large part because most of the studies are American and do not fit well into the Canadian scene. Relevant Canadian findings are reviewed and compared to the US data. There is some evidence that Canadian patients may be diverted from the criminal justice system more often than in the US, where there are fewer resources. However, this conclusion must be tempered by the fact that Canadian surveys have found high rates of mental disorder among prison and jail inmates.

Canada↗
PubMed1992

The NMDA receptor antagonist D-2-amino-5-phosphonopentanoate (D-AP5) impairs spatial learning and LTP in vivo at intracerebral concentrations comparable to those that block LTP in vitro.

This series of experiments investigated whether the NMDA receptor antagonist D-2-amino-5-phosphonopentanoate (D-AP5) could induce impairments of spatial learning across a dose range comparable to its impairment of hippocampal long-term potentiation (LTP) in vivo. Estimations of the extracellular concentration of D-AP5 in hippocampus using microdialysis were also made to compare whether these impairments occur at concentrations similar to those required to impair LTP in the in vitro hippocampal slice. Rats were chronically infused with D-AP5 into the lateral ventricle at a range of concentrations (0-50 mM) via osmotic minipumps. They were first trained to find and escape onto a hidden platform in an open-field water maze task. After the behavioral learning, they were anesthetized with urethane and an attempt was made to evoke and monitor hippocampal LTP. Extracellular samples of D-AP5 in hippocampus were then taken using microdialysis, and finally, the animals were killed and tissue samples dissected. The microdialysis and tissue samples were analyzed for D-AP5 content using HPLC with fluorescence detection. The results established, first, that D-AP5 impairs spatial learning in a linear dose-dependent manner, highly correlated with its corresponding impairment of hippocampal LTP in vivo. No concentration of D-AP5 was observed to block LTP without affecting learning. Second, the microdialysis estimates indicated that, subject to certain assumptions, D-AP5 causes these impairments at extracellular concentrations comparable to those that impair LTP in vitro. Third, comparison of the whole tissue and microdialysis samples revealed a concentration ratio of approximately 30:1, indicating that 97% of the intracerebral D-AP5 is inaccessible to the dialysis probes. Infusion of 20 mM EGTA was found to cause a sevenfold increase in D-AP5 in the dialysis perfusates, suggesting that at least part of the inaccessible D-AP5 is trapped by a calcium-dependent mechanism. Two further behavioral control studies indicated that the D-AP5-induced impairment of spatial learning is unlikely to be secondary to a drug-induced motor disturbance, and that the performance of the D-AP5 group whose concentration was just sufficient to block hippocampal LTP completely was statistically indistinguishable from that of a group of rats with bilateral hippocampal lesions induced by ibotenic acid. Taken together, these findings offer support for the hypothesis that activation of NMDA receptors is necessary for certain kinds of learning.

2-Amino-5-phosphonovalerate↗
PubMed1991

The receptor for ciliary neurotrophic factor.

Although neurotrophic factors were originally isolated on the basis of their ability to support the survival of neurons, these molecules are now thought to influence many aspects of the development and maintenance of the nervous system. Identifying the receptors for these neurotrophic factors should aid in identifying the cells on which these factors act and in understanding their precise mechanisms of action. A "tagged-ligand panning" procedure was used to clone a receptor for ciliary neurotrophic factor (CNTF). This receptor is expressed exclusively within the nervous system and skeletal muscle. The CNTF receptor has a structure unrelated to the receptors utilized by the nerve growth factor family of neurotrophic molecules, but instead is most homologous to the receptor for a cytokine, interleukin-6. This similarity suggestes that the CNTF receptor, like the interleukin-6 receptor, requires a second, signal-transducing component. In contrast to all known receptors, the CNTF receptor is anchored to cell membranes by a glycosyl-phosphatidylinositol linkage.

Amino Acid Sequence↗
PubMed1991

A case-control study of oral cancer and pre-diagnostic concentrations of selenium and zinc in nail tissue.

A case-control study of oral cancer was conducted in western Washington state between 1983 and 1987. Cases (n = 379) were identified through a population-based registry, and controls (n = 514) were selected by telephone using random digit dialing. Subjects participated in a personal interview, completed a food-frequency questionnaire, and submitted clippings from the nails of each great toe for the determination of selenium and zinc concentrations. The odds ratio (OR) for low selenium levels in nail tissue (lowest 25% of the distribution compared to the upper 75%) was 1.4 (95% confidence interval (CI) 1.0-2.2). Likewise, the odds ratio for low zinc levels in nails was 1.6 (95% CI 1.0-2.3), but for low dietary zinc was 1.0 (95% CI 0.7-1.7). Men with oral cancer had lower nail selenium levels than did the controls (OR = 1.9), but women with oral cancer did not (OR = 0.6). Individuals 20 to 39 years of age with oral cancer, in particular, were more likely to have lower selenium levels in nail tissue than controls (OR = 16.4). There was a significant interaction between selenium and ascorbic acid levels which could not be explained by cigarette use. Subjects at greatest risk had low levels of both nutrients (OR = 3.8 for smokers and OR = 5.7 for non-smokers). However, since the elements were deposited in the nail matrix close to the date of diagnosis, the differences in the element concentrations between cases and controls may have been a result of the disease. Further etiologic studies of selenium, vitamin intake and oral carcinoma are warranted.

Adult↗
PubMed1991

Presence of an SH2 domain in the actin-binding protein tensin.

The molecular cloning of the complementary DNA coding for a 90-kilodalton fragment of tensin, an actin-binding component of focal contacts and other submembraneous cytoskeletal structures, is reported. The derived amino acid sequence revealed the presence of a Src homology 2 (SH2) domain. This domain is shared by a number of signal transduction proteins including nonreceptor tyrosine kinases such as Abl, Fps, Src, and Src family members, the transforming protein Crk, phospholipase C-gamma 1, PI-3 (phosphatidylinositol) kinase, and guanosine triphosphatase-activating protein (GAP). Like the SH2 domain found in Src, Crk, and Abl, the SH2 domain of tensin bound specifically to a number of phosphotyrosine-containing proteins from v-src-transformed cells. Tensin was also found to be phosphorylated on tyrosine residues. These findings suggest that by possessing both actin-binding and phosphotyrosine-binding activities and being itself a target for tyrosine kinases, tensin may link signal transduction pathways with the cytoskeleton.

Actins↗