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Biomedical subjects

W C Reeves

Publications and source records attributed to W C Reeves.

At least 145 records · Page 8Linked to original sources
PubMed1989

Parity as a risk factor for cervical cancer.

In a case-control study of 759 invasive cervical cancer patients and 1,430 controls in Colombia, Costa Rica, Mexico, and Panama conducted during 1986-1987, an association with number of pregnancies persisted after adjustment for sexual and socioeconomic variables. Risks rose steadily to 5.1 (95% confidence interval 2.7-9.7) for those with 14 or more pregnancies and a relation of risk to multiparity was observed in all four study countries. Pregnancy associations appeared to relate to the number of live births rather than to miscarriages or abortions, with multiparity relations most pronounced among premenopausal women and oral contraceptive users. Human papillomaviruses types 16 and 18, as measured by filter in situ hybridization, were not significantly associated with number of births and did not explain the strong relation of parity to risk. Our results indicate the need for further consideration of reproductive factors on cervical cancer risk, with attention given to possible mechanisms of action, including hormonal factors and cervical trauma.

Adult↗
PubMed1989

Prevalence of neutralizing antibodies against California and Bunyamwera serogroup viruses in deer from mountainous areas of California.

Plaque reduction-serum dilution neutralization was used to evaluate the status of bunyavirus activity in deer in mountainous areas of California. Antibodies against 9 bunyaviruses were measured in 337 mule deer (Odocoileus hemionus hemionus, O. hemionus californicus, and O. hemionus inyoensis) and black-tailed deer (O. hemionus columbianus). More deer from high mountainous areas had neutralizing antibodies against Jamestown Canyon virus than did deer from low mountainous areas (23% vs. 9%; P less than 0.01). This finding is consistent with transmission by snow pool Aedes mosquitoes. Results for Jerry Slough virus were nearly identical to those for Jamestown Canyon virus, which is further evidence that these are strains of the same virus. Neutralizing antibodies against Northway virus were present in 26% of deer from high mountainous areas and 23% of deer from low mountainous areas, suggesting the involvement of a widespread vector, such as Culiseta inornata. Northway virus is not known to occur outside of Alaska and northwestern Canada. Low prevalences of antibodies were detected in deer to California encephalitis, La Crosse, and snowshoe hare viruses of the California serogroup; and Cache Valley, Lokern, and Main Drain viruses of the Bunyamwera serogroup.

Animals↗
PubMed1988

Inadequate subendocardial oxygen delivery during perfluorocarbon perfusion in a canine model of ischemia.

Perfusion of the coronary artery distal to an occlusion was performed in 16 canine preparations to compare the mechanical perfusion of autologous blood to the perfluorocarbon fluosol DA, 20% emulsion (FDA-20). Both substances were perfused under similar conditions (30, 60, and 80 ml/min) and regional electrograms, contractility, and coronary perfusion were measured relative to native coronary perfusion. Autologous blood (60 and 80 ml/min) produced a significant increase in regional (epicardial, midmyocardial, and endocardial) and transmural flow, but not in the endocardial/epicardial perfusion ratio. No other significant changes were observed during autologous blood perfusion. In contrast, FDA-20 perfusion resulted in significant ST depression (-1.8 +/- 0.2, -1.7 +/- 0.2, and -1.3 +/- 0.3 mm) at 30, 60, and 80 ml/min, respectively. FDA-20 also induced a significant decrease in distal diastolic coronary pressure and resistance, a significant decrease in the endocardial/epicardial perfusion ratio at all three perfusion rates, and a significant reduction in delivery of O2 to the subendocardium. These results indicate that autologous blood perfusion of the distal coronary artery during occlusion preserves myocardial function to a better degree than does FDA-20.

Animals↗
PubMed1988

Intracoronary echo-contrast agents: abnormalities in myocardial function in a normal and reduced coronary perfusion model in dogs.

Two-dimensional echocardiography using echo-contrast enhancing agents is a promising technique for evaluating myocardial perfusion. However, the potential deleterious effects of injection of echo-enhancing agents into the coronary circulation have not been well evaluated. We utilized two experimental canine models in which the left anterior descending coronary artery was cannulated and perfused continuously by the left common carotid at normal and reduced coronary flows. Analysis of myocardial function included regional left ventricular systolic function by ultrasonic crystals, subendocardial ST segment shifts, left ventricular dP/dr analysis and measurements of coronary blood flow. One ml of each echo-contrast agent was injected into the left anterior descending coronary artery during normal coronary flow. Echo-enhancing agents included: sonicated 70% sorbitol, 50% dextrose, and 6% dextran, hand-agitated Renografin-saline, and unagitated 0.15% hydrogen peroxide, 20% fat emulsion and oxygenated Oxypherol, a perfluorocarbon compound. Two-dimensional echocardiography determined that all echo-enhancing agents except for 20% fat emulsion and Oxypherol produced good myocardial enhancement. All echo-enhancing agents which produced a good contrast effect did so at the expense of significant reversible contractile abnormalities. Each produced more than a 50% reduction in percent segment shortening. Sorbitol and hydrogen peroxide produced the most severe contractile disturbances. In the normal flow model, sorbitol produced systolic bulging and hydrogen peroxide an 83% reduction in percent segment shortening. Hydrogen peroxide induced systolic bulging in the reduced coronary flow model. Other abnormalities induced by echo-enhancing agents included ST segment shifts and malignant ventricular arrhythmias. Six percent dextran produced a good contrast effect with the least harmful myocardial consequences.

Animals↗
PubMed1988

Human T-cell lymphotropic virus type I (HTLV-I) seroepidemiology and risk factors in metropolitan Panamá.

Human T-cell lymphotropic virus type I (HTLV-I) infection and associated hematologic malignancies cluster in Japan, the Caribbean basin, and Central Africa. The authors believe that this study of HTLV-I seroepidemiology in the Republic of Panamá is the first detailed analytic study of environmental factors pertaining to HTLV-I infection in representative tropical populations. The study analyzed observational data concerning housing conditions, family composition, and demographic and behavioral attributes as risk factors for HTLV-I infection (HTLV-I antibody). The 745 study subjects were residents of representative households in Panamá City and Colón. Overall, 5% of sera had antibody against HTLV-I, detected by enzyme-linked immunosorbent assay and confirmed by competitive binding. Housing conditions, race, and socioeconomic factors were not associated with infection nor did infection cluster in families. Interview of 706 women enrolled in cervical cancer studies documented that female sexual experience (number of marriages or sexual partners) was associated with HTLV-I infection. These findings support the hypothesis that HTLV-I is not transmitted by casual contact but requires exposures involving exchange of bodily fluids.

Adolescent↗
PubMed1988

Human immunodeficiency virus infection in the Republic of Panama.

Thirty-one documented acquired immune deficiency syndrome (AIDS) cases occurred in Panama during 1984-1987. Twenty-three (74%) patients were homosexual males and all but 2 patients recognized prior to June 1987 have died. To identify risk factors for human immunodeficiency virus infection, 287 male homosexual residents of Panama City were enrolled in a cross-sectional study. Nine had human immunodeficiency virus (HIV) antibody. Travel to the United States, homosexual relations with United States nationals in Panama, and sexual contacts in Panamanian clubs and bars were associated with human immunodeficiency virus infection by logistic regression analysis. Number of different male sex partners per year was identified but did not enter the logistic model at a significant level. To estimate seroprevalence in other high risk populations, 183 Panama City female prostitutes and 55 homosexual males from the rural Azuero peninsula were screened; none were seropositive. Eighty-four percent of Panamanian hemophiliacs had antibody; infection was related to factor VIII transfusions. Two of 182 sickle cell anemia patients and 15 of 7,720 volunteer blood donors were positive.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Case-control study of human papillomaviruses and cervical cancer in Latin America.

Human papillomavirus (HPV) types 16 and 18 have been implicated as risk factors for cervical dysplasia and neoplasia. However, most studies have been observational, uncontrolled and conducted in populations at low risk for invasive cancer. We report a pilot case-control study of incident invasive cervical cancer in Panama, Costa Rica and Bogota, Colombia. Between July and September 1985 we enrolled 46 consecutive newly diagnosed invasive cervical cancer cases and 51 age-matched control women. Subjects were interviewed and samples collected for HPV DNA assays. HPV infection was defined by a filter in situ DNA hybridization technique under non-stringent and stringent conditions against HPV-6/11, 16 and 18 DNA probes. More cases (91%) than controls (63%) had HPV DNA detected (non-stringent) and more cases than controls had HPV-16 or 18 DNA (67% vs. 43%, p = 0.02). Age at first intercourse was the most significant risk factor for HPV 16/18 infection in all subjects. Smoking was significantly associated with cervical cancer (52% of cases vs. 27% controls) but was not associated with HPV infection.

Adult↗
PubMed1987

Aseptic meningitis due to echovirus 4 in Panama City, Republic of Panama.

Between September 23 and November 30, 1981, 1,032 children from Panamá City, Republic of Panamá were hospitalized with aseptic meningitis. Forty-four per cent of the cases were in the age group 5-9 years old; the disease was mild and self-limiting with an average hospital stay of five days. Echovirus 4 isolates were obtained from 48 of 160 patients. To identify risk factors associated with the epidemic, the authors randomly selected 10 per cent of hospitalized cases and conducted a family-based seroepidemiologic study. The closest neighboring house with at least one child younger than 15 years was similarly studied as a control. In total, 182 households and 1,083 of 1,177 residents were included. No risk factors ascertained by the study were associated with aseptic meningitis; however, several factors were related to recent echovirus 4 infection. Overall, 56 per cent of cases had echovirus 4 antibody, as did 29 per cent of their family members and 19 per cent of control family members. Children who attended kindergarten or primary school were more likely to have antibody than other household members and, within case families, individuals involved in child-care had an excess risk for infection.

Adolescent↗