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S Davis

Publications and source records attributed to S Davis.

At least 325 records · Page 18Linked to original sources
PubMed1990

A dose-related impairment of spatial learning by the NMDA receptor antagonist, 2-amino-5-phosphonovalerate (AP5).

This paper describes an experiment which further tested the hypothesis that activation of N-methyl-D-aspartate receptors plays an important role in the neural mechanisms underlying certain kinds of learning and memory. The results demonstrate that a selective N-methyl-D-aspartate receptor antagonist, D-2-amino-5-phosphonovalerate, causes a dose-related and correlated impairment of both spatial learning and hippocampal long term potentiation in vivo. No dose of D-2-amino-5-phosphonovalerate was found to block long term potentiation without affecting spatial learning. These data therefore support the proposed link between long term potentiation and certain kinds of learning, and the role of N-methyl-D-aspartate receptors in both processes.

2-Amino-5-phosphonovalerate↗
PubMed1990

Evaluation of an oncology curriculum.

This report describes and presents an evaluation of the undergraduate component of the Cancer Education Program at The Bowman Gray School of Medicine. New learning objectives on cancer were introduced into the second and third year of the Medical School curriculum. A twenty-five question multiple choice examination measured the accomplishment of the new objectives. Students in the class of 1985, who did not receive instruction on the new objectives as part of their formal medical education, served as a control. Students in the classes of 1986 and 1987, who respectively received partial and full exposure to the new objectives, served as experimental groups. Despite limitations in the evaluation procedure, data obtained from the study suggested the possibility of a small but meaningful increase in overall knowledge and specific gains in both students' knowledge and their perceptions of being better prepared to deal with psychosocial aspects of cancer.

Curriculum↗
PubMed1990

Cigarette smoking and acute nonlymphocytic leukemia.

In a case-control study of acute nonlymphocytic leukemia in western Washington state, cigarette smokers experienced a twofold increased risk of acute nonlymphocytic leukemia compared with nonsmokers. Risk increased significantly with the number of pack-years smoked (p = 0.0008) and decreased with the number of years stopped smoking (p = 0.15). The increased risk in smokers appeared to be limited to those who inhaled into the chest. The authors suggest that further studies of this potential relation are warranted, especially since the prevalence of cigarette smoking is relatively high in our society.

Case-Control Studies↗
PubMed1990

Diet and the risk of pancreatic cancer in men.

To examine the relation between diet and pancreatic cancer, we conducted a population-based case-control study in western Washington. Cases (n = 148) were married men, aged 20-74 years, who were diagnosed with pancreatic cancer from July 1982 to June 1986. Controls (n = 188), identified by random digit dialing, were frequency matched to the cases by 5-year age groups. Wives responded as surrogates for both cases and controls. Wives were interviewed by telephone, and they completed a mailed, self-administered food frequency questionnaire. Results indicated that pancreatic cancer risk increased with increasing protein intake. The increased risk for heavy consumers of protein was largely confined to individuals aged 65 years and above. In that group, the odds ratio for those in the highest quartile of protein intake, relative to the lowest, was 6.0 (95% confidence interval 1.7-20.6). No association was found between pancreatic cancer risk and the intake of total fat, saturated fat, cholesterol, omega-3 fatty acids, or vitamins A and C. There was an unexpected inverse association between calcium intake and pancreatic cancer risk in these data. These findings are discussed in relation to possible etiologic mechanisms that they suggest.

Adult↗
PubMed1990

Qualitative and quantitative assessment of geographic clustering of population samples selected using different methods of random digit dialing.

Random digit dialing is a method commonly used to select random population samples in epidemiologic research. Although random digit dialing is generally presumed to provide representative samples, coverage and nonresponse errors may affect the degree to which the sample is representative. The present investigation was undertaken to determine whether the geographic distributions of samples selected using variations of the basic random digit dialing technique accurately reflect the underlying population distribution, and if not, whether such samples tend to be either more or less dispersed than the populations from which they were selected. Data regarding control groups from three case-control studies conducted from 1983-1986 were utilized. The residence addresses of 998 controls were located and assigned an X-Y coordinate and census tract designation within a three-county geographic area in northwest Washington State. Initially, the spatial distributions of controls were examined graphically in relation to the age-sex structure of the underlying population. No differences in geographic pattern were apparent. A more formal statistical evaluation was conducted based on centrographic techniques utilizing two measures to describe the spatial distribution of a set of points. Results indicate that the samples chosen were neither more nor less dispersed than the underlying populations. However, the geographic centers of samples selected using primary numbers tended to be shifted from the centers of their respective populations. Several possible explanations for such shifts are considered, and extensions of the analytical approach are suggested in relation to the further evaluation of population sampling and the investigation of space-time aggregations of disease.

Adult↗
PubMed1990

Point pattern analysis of the spatial proximity of residences prior to diagnosis of persons with Hodgkin's disease.

There is some evidence to suggest that the etiology of Hodgkin's disease includes an infectious component. One approach to investigating this possibility is a formal assessment of the geographic and temporal variation in the incidence of the disease. The present study was designed to better evaluate space-time patterns of residence prior to diagnosis of persons with Hodgkin's disease. Lifetime residential histories were obtained from 279 incident cases of Hodgkin's disease diagnosed between 1974 and 1982 in a defined population in northwestern Washington State, and a similar number of population controls matched to the cases by age, sex, and socioeconomic status. A method of point pattern analysis was modified for use in this context to compare the spatial proximity of case residences to that expected under the null assumption of no difference between the spatial pattern of case and control residences. Analyses were applied within temporal groupings of residences specified a priori assuming 1) no specified latency, 2) four different 5-year latent intervals, and 3) three age at exposure intervals. Assuming no latency, there is no evidence that case residences are more or less clustered than would be expected by chance. Assuming latent intervals of up to 15 years prior to diagnosis, case residences are less clustered than expected, particularly among those who developed Hodgkin's disease after the age of 40 years. In contrast, there is suggestive evidence that persons diagnosed with Hodgkin's disease after age 40 years lived closer together than expected as young children and teenagers. These results illustrate the need to focus such analyses on specific time intervals defined a priori to most likely represent periods of greatest etiologic relevance. To the extent that these findings are not the result of some unknown artifact of the method itself, they may serve to focus additional attention on childhood environment as a particularly important period in the etiology of this disease. Furthermore, the analytic method employed may be useful in identifying space-time clustering using population-based data in other etiologic settings.

Adolescent↗
PubMed1990

Role of catecholamines in regulating ovine median eminence blood flow.

Blood flow was measured in the ovine median eminence and neural lobe before and after the intravenous infusion of dopamine (n = 7), the D1 agonist SKF 38393 (n = 4), the D2 agonist bromocriptine (n = 4), and the dopamine antagonist haloperidol (n = 5). It was also measured before and after the intracarotid infusion of dopamine into eight naive sheep and seven sheep pretreated with phenoxybenzamine. Radiolabeled microspheres were used to determine regional cerebral and regional neurohypophysial blood flows (RNHBF) in these 35 adult female sheep anesthetized with pentobarbital sodium. Samples for serum prolactin measurement by radioimmunoassay were obtained before and after drug infusion. Intravenous dopamine infusion did not change median eminence or neural lobe blood flow (RNHBF) but increased renal and choroid plexus blood flow. Intravenous haloperidol caused a significant fall in RNHBF and blood flow in choroid plexus, caudate nucleus, and kidneys. Intracarotid dopamine infusion decreased RNHBF but increased choroid plexus blood flow. RNHBF was significantly greater in the seven sheep pretreated with phenoxybenzamine than in the eight naive sheep. These findings do not support a role for dopamine in the regulation of median eminence blood flow. The last observation does add support to the hypothesis that norepinephrine or epinephrine interaction with alpha-receptors plays a role in the control of ovine median eminence blood flow and hence in the regulation of delivery of humoral messages from the brain to the anterior pituitary gland.

Animals↗
PubMed1990

A single-photon emission computed tomography study of hypoperfusion after subarachnoid hemorrhage.

We used single-photon emission computed tomography with technetium-99m hexamethylpropylene amine oxime in 18 studies on 13 patients with subarachnoid hemorrhage to determine whether any changes in cerebral blood flow could be correlated with clinical or computed tomographic evidence of delayed ischemia. Among the seven patients without focal neurologic deficits, regional cerebral hypoperfusion was demonstrated in only one who died. Among the 10 patients with aneurysmal subarachnoid hemorrhage, one died before surgery, and six developed postoperative delayed ischemic deficits, of whom two died. Among the patients with angiographically documented aneurysms, regional hypoperfusion correlated with the presence and severity of delayed neurologic deficits, whereas correlative computed tomographic scans showed either early infarction or no relevant abnormality. This technique facilitates early diagnosis of cerebral tissue hypoperfusion due to vasospasm after subarachnoid hemorrhage.

Cerebral Angiography↗
PubMed1990

Cerebrospinal fluid biochemistry in the diagnosis of multiple sclerosis.

The Poser criteria for diagnosing multiple sclerosis (MS) includes clinical, paraclinical and laboratory information. We studied the influence of cerebrospinal fluid (CSF) biochemistry results on the categorisation of patients with suspected MS. A retrospective study was made of 138 patients who had CSF samples sent over a 1 year period to the laboratory for examination for oligoclonal bands. Using the Poser criteria, 23 patients were diagnosed as having definite MS and one patient as probable MS. Cerebrospinal fluid biochemistry upgraded the categorisation from probable to definite MS in 16 of these 24 patients (66%). In this study, we found oligoclonal bands to be more sensitive in the diagnosis of MS (96%) than either the concentration of IgG in the CSF (43.5%) or the IgG expressed as a percentage of the total protein in the CSF (71%). We conclude that CSF biochemistry is a valuable investigation in the evaluation of patients with suspected MS.

Adolescent↗
PubMed1990

Ovarian choriocarcinoma: a difficult diagnosis of an unusual tumor and a review of the hook effect.

Ovarian choriocarcinoma is difficult to diagnose in the reproductive-age patient. A case of nongestational ovarian choriocarcinoma is discussed which presented like a molar pregnancy initially. Because of falsely low beta-hCG values (283 mIU/L) caused by the high-dose "hook effect" in the double antibody immunoassay system, however, a diagnosis of ectopic pregnancy was entertained. At laparotomy, a large necrotic ovarian choriocarcinoma was found along with large theca lutein cysts. The hook effect may mislead the clinician, and it is important to recognize this effect to avoid misdiagnosis.

Adult↗
PubMed1989

Noncystic "increased" periventricular echogenicity and other mild cranial sonographic abnormalities: predictors of outcome in low birth weight infants.

The sonograms of 71 low birth weight infants were retrospectively reviewed and compared with results of neuromotor examinations at 24 months of age to determine whether mild abnormalities commonly detected on cranial sonograms (including milder grades of hemorrhage, ventricular dilation, and noncystic increases in periventricular echogenicity) were correlated with future neurologic handicaps. Of the 71 infants studied, increased periventricular echoes were noted in 20 (28%), Grade 1 or 2 intracranial hemorrhage in 31 (43%), and mild-moderate ventriculomegaly in 28 (39%). Neuromotor handicaps were detected in 15 (21%). No significant correlation was found between the above sonographic abnormalities and the incidence of future neuromotor handicaps. When those neonates with asymmetric mild-moderate ventriculomegaly were separately analyzed, this group was found to have more neuromotor handicaps (p less than 0.05) than those with normal ventricular size, and this finding warrants future study. Importantly, early cranial sonograms were completely normal in 12% of those infants with neuromotor handicaps. We conclude that the presence of mild cranial sonographic abnormalities (including mildly increased periventricular echogenicity) in these infants is not well correlated with neuromotor handicaps detected at 24 months of age.

Brain↗
PubMed1989

Differences in the sex ratio of laryngeal cancer incidence rates by anatomic subsite.

The incidence data from nine population-based cancer registries participating in the Surveillance, Epidemiology and End Results program in the U.S. suggest that squamous cell carcinoma arising from different parts of the larynx have different etiologic influences. The male to female rate ratio for laryngeal cancers was substantially higher in the glottic region (9.2 among whites and 11.8 among blacks) than in other subsites (approx. 3-5 in both races). The sex rate ratios were uniformly higher for glottic tumors in all age groups, and these ratios increased more rapidly with age for glottic than for supraglottic tumors. Factors that are closely related to sex other than smoking and drinking behavior are responsible for the considerably high ratio of male to female rates of the glottic tumors. Future etiologic studies should investigate the possible differential effect of hormonal or other sex-related factors on different anatomic subsites within the larynx.

Alcohol Drinking↗
PubMed1989

Acute myelocytic leukemia and prior allergies.

The relationship between prior allergies and adult acute myelocytic leukemia was investigated in a population-based case-control study. Based on data from personal interviews of 98 cases and 133 controls, a history of any type of allergy was associated with a significantly decreased risk of acute myelocytic leukemia (OR = 0.35, 95% CI = 0.20-0.60). Risk declined with the total number of specific allergies reported (p less than 0.001), and was reduced in relation to a history of prior asthma, eczema and hives. The implications of these findings in relation to natural immune surveillance against developing neoplasms are discussed.

Adult↗
PubMed1989

Pregnancy in adolescents.

The United States must improve its efforts to reduce teen pregnancy. We occupy an alarming position in the developed world from the standpoint of the magnitude of the pregnancy issue. While our society promotes sexuality to sell all sorts of consumer goods, it still refuses for the most part to make contraceptives familiar and available to sexually active teens. The youngest adolescents, 10 to 14 years, are having sex and babies at an increasing rate. Their children will have limited futures. Only by stepping up our efforts to prevent early pregnancy will we make possible a life of opportunity and choice for the young people of our country. Consequences will be costly and tragic if we do not.

Adolescent↗