Search PubMed⌕ Search

Biomedical subjects

W C Reeves

Publications and source records attributed to W C Reeves.

At least 55 records · Page 3Linked to original sources
PubMed1997

Mouse and baby chicken virulence of enzootic strains of western equine encephalomyelitis virus from California.

Eight enzootic strains of western equine encephalomyelitis (WEE) virus isolated from Culex tarsalis or Aedes melanimon collected in several geographic areas of California were evaluated for their virulence in suckling mice, adult mice, and one-day-old baby chickens. The epidemic Fleming strain and the cloned B628(Cl 15) variant were used as virulent and avirulent control viruses, respectively, in adult mice. Enzootic strains of WEE virus were grouped into three phenotypes on the basis of their neurovirulent and neuroinvasive properties in adult mice. Three strains possessed high neurovirulence and were neuroinvasive; three strains had intermediate neurovirulence and lacked neuroinvasiveness; and two strains had low to nil neurovirulence and were non-neuroinvasive. In fact, five of the eight enzootic strains lacked neuroinvasiveness. Interestingly, highly virulent enzootic strains of WEE virus were isolated from Cx. tarsalis collected in the Sacramento Valley during 1994 and 1995 in the absence of identified human disease. The Fleming strain, the B628(Cl 15) variant, and four enzootic strains from the Sacramento Valley were virulent for baby chickens following subcutaneous inoculation. Thus, inoculation into baby chicks cannot discriminate between WEE viruses that are virulent and avirulent for adult mice.

Aedes↗
PubMed1997

Human papillomavirus type in anal epithelial lesions is influenced by human immunodeficiency virus.

BACKGROUND AND OBJECTIVE: Infection with human immunodeficiency virus (HIV) increases the risk for human papillomavirus (HPV)-associated genital neoplasia. Human immunodeficiency virus-infected patients also have higher rates of treatment failure and more rapid neoplastic progression. Impaired immune function does not entirely explain these clinical observations. This pilot project was designed to investigate the hypothesis that HIV infection is associated with changes in HPV type and integration within anogenital lesions that could explain the increased risk of neoplastic progression. METHODS: Anal neoplastic lesions from patients with and without HIV infection were analyzed for the presence, type, and integration status of HPV by colorimetric in situ hybridization. Tissue localization of HIV was evaluated by p24 immunohistochemistry and HIV-1 DNA polymerase chain reaction. Results for matched histology were compared for the two patient groups. RESULTS: For all lesions, the presence of high-risk HPV types and multiple HPV types was strongly associated with HIV infection (P = .003 and .0003, respectively). For lesions with matched histology there was no association of HPV integration with HIV status. Tissue localization of HIV did not significantly influence HPV type or integration. CONCLUSIONS: The presence of high-risk HPV types and multiple types within low-grade lesions may explain the increased risk of neoplastic progression in HIV patients. Colocalization of HIV and HPV does not appear to be required for this effect. There is no evidence that HPV integration is influenced by HIV infection.

Adolescent↗
PubMed1996

Geographic distribution and serologic and genomic characterization of Morro Bay virus, a newly recognized bunyavirus.

More than 75,000 immature mosquitoes in three genera were collected from coastal California, reared to the adult stage, and tested for virus by plaque assay in Vero cell cultures. Twenty-six strains of Morro Bay (MB) virus, a newly recognized member of the California (CAL) serogroup, were isolated from Aedes squamiger, a pestiferous salt marsh mosquito species restricted to intertidal salt marshes in coastal California and Baja California. The geographic distribution of the isolates was 10 from San Luis Obispo County, one each from Santa Barbara and Orange Counties, and 14 from San Diego County. No virus isolations were made from 23,157 Ae. squamiger collected north of San Luis Obispo County (midpoint in the geographic range of this species in California). Thus, MB virus infection in Ae. squamiger appears to be restricted to the southern range of this species in California. Serum dilution neutralization tests indicated that MB virus represents a novel subtype of the California encephalitis (CE) serotype within the CAL serogroup. Comparative analyses of genomic sequence data from four geographically distinct MB virus isolates indicated that the isolates are genetically similar to each other and distinct from other CE serotype bunyaviruses. Phylogenetic analysis of nucleocapsid protein gene sequence data indicated that MB virus represents a distinct lineage within the CE serotype and thus supports the serologic classification of MB virus as a distinct CAL serogroup virus.

Aedes↗
PubMed1996

Ecology of Jamestown Canyon virus (Bunyaviridae: California serogroup) in coastal California.

This paper reports the first isolation of Jamestown Canyon (JC) virus from coastal California and the results of tests for antibody to JC virus in mammals living in coastal California. The virus isolation was made from a pool of 50 Aedes dorsalis females collected as adults from Morro Bay, San Luis Obispo County, California. The virus isolate was identified by two-way plaque reduction-serum dilution neutralization tests done in Vero cell cultures. Sera from the mammals were tested for antibody to JC virus by a plaque-reduction serum dilution neutralization method. A high prevalence of JC virus-specific antibody was found in horses and cattle sampled from Morro Bay. This finding is additional evidence for the presence of a virus antigenically identical or closely related to JC virus in Morro Bay and indicates that the vectors of the virus in Morro Bay feed on large mammals. A high prevalence of virus-specific antibody was also found in horses sampled from Marin and San Diego counties. This finding suggests that viruses antigenically identical or closely related to JC virus are geographically widespread in coastal California.

Aedes↗
PubMed1995

Cervical cancer survival in a high risk urban population.

BACKGROUND: Cervical cancer remains an important public health problem, particularly for the urban minority population. To the authors' knowledge, determinants of cervical cancer survival have not been studied in this high risk population. METHODS: This study included all 158 women diagnosed and treated for invasive cervical cancer from January 1, 1986, through December 31, 1992, at the Grady Memorial Hospital and Clinics (Atlanta, GA). Medical records were abstracted to determine age at diagnosis, race, International Federation of Gynecology and Obstetrics (FIGO) clinical stage, treatment, and survival. Pathologic material was reviewed to confirm the diagnosis. RESULTS: Most patients (80%) were African American, and the stage distribution was similar for African American and white patients. Sixty-six (42%) had FIGO Stage I disease; 50%, Stage II or III; and 8%, Stage IV. Four-year actuarial survival differed significantly according to clinical stage (Ia = 94%, Ib = 79%, II = 39%, III = 26%, IV = 0%). Overall survival was lower for patients with glandular carcinomas than for those with squamous cell carcinomas (26% vs. 55%, P = 0.09). This difference was almost entirely due to increased mortality in patients with Stage Ib adenocarcinomas (53% vs. 88% for squamous cell carcinoma, Stage Ib, P = 0.03). CONCLUSIONS: The major prognostic markers for cervical cancer survival in this high risk patient population were clinical stage and histology, factors identical to those identified for other populations.

Black or African American↗
PubMed1995

Seroepidemiology of chronic fatigue syndrome: a case-control study.

We performed serological testing for a large number of infectious agents in 26 patients from Atlanta who had chronic fatigue syndrome (CFS) and in 50 controls matched by age, race, and sex. We did not find any agent associated with CFS. In addition, we did not find elevated levels of antibody to any of a wide range of agents examined. In particular, we did not find elevated titers of antibody to any herpesvirus, nor did we find evidence of enteroviral exposure in this group of patients.

Adolescent↗
PubMed1995

Human papillomavirus infection and associated disease in persons infected with human immunodeficiency virus.

Genital infection with human papillomavirus (HPV) is the most common sexually transmitted infection in the United States. Genital or anal infection with oncogenic types of HPV, particularly types 16 and 18, can cause precancerous lesions of the squamous epithelium. Infection with human immunodeficiency virus (HIV) increases the risk for HPV-associated genital neoplasias in both women and men. Detectable cervical and anal HPV infection is more prevalent among women and men with HIV infection than among those who are HIV-seronegative, and the magnitude of the increase in prevalence is proportionate to the severity of immunosuppression. Coinfection with HIV and HPV increases the risk for genital intraepithelial neoplasia, and the increase in this risk also reflects the severity of immunosuppression. One difficulty complicating elucidation of the association between HIV and HPV infections is that the risk factors for acquisition and transmission of the two viruses are similar. The strength of this association represents a burgeoning health problem, yet there are no treatment guidelines aimed specifically at HIV-infected individuals with HPV-associated genital neoplasias. Treatment of HPV-associated cervical disease in HIV-infected women may be further complicated by a greater risk of treatment failure and recurrence than exists among HIV-seronegative women; it is not known whether dysplasia progresses to invasive disease more rapidly in women infected with HIV. A thorough understanding of the associations among HIV, HPV, and HPV-associated disease is essential to the development of effective strategies for intervention and prevention.

Female↗
PubMed1995

Human papillomavirus and disease-free survival in FIGO stage Ib cervical cancer.

To determine if human papillomavirus (HPV) in the primary tumor was associated with disease-free survival of stage Ib cervical cancer patients, archival tissues from 47 patients were analyzed for HPV DNA by in situ hybridization (ISH) and polymerase chain reaction. HPV integration was determined by ISH signal pattern. Laboratory data were correlated with clinical parameters and disease-free survival. Kaplan-Meier estimates of 4-year disease-free survival were 56% in women with HPV detected in the primary tumor by ISH and 100% for women in whom HPV was not detected (P = .02). Four-year disease-free survival was 39% for patients with integrated HPV in the primary tumor (P = .005 vs. HPV-negative tumors and .05 vs. HPV episomal or episomal/integrated). HPV detection and integration state was not associated with any other clinical variable. Detection of integrated HPV DNA in the primary tumor was strongly associated with treatment failure.

Adult↗
PubMed1994

Norepinephrine-induced left ventricular dysfunction in anesthetized and conscious, sedated dogs.

These studies were conducted to evaluate effects of high dose norepinephrine infusion on left ventricular function in anesthetized and conscious dogs. Separate groups of pentobarbital anesthetized closed-chest dogs received norepinephrine infusion for 90 min followed by 1 h of recovery. Arterial pressure, electrocardiogram, two-dimensional echocardiogram and an equilibrium radionuclide angiogram were monitored. One hour following infusion of norepinephrine, left ventricular ejection fraction was reduced in a dose-dependent fashion. Fractional shortening was similarly reduced, with increased left ventricular systolic and diastolic dimensions also observed. Left ventricular end-systolic wall stress was increased at 60 min following infusion of norepinephrine but not saline: saline, 68 +/- 8, norepinephrine, 4 micrograms/kg/min, 113 +/- 8 g/cm2. The left ventricular end-systolic wall stress/fractional shortening relationship showed reduction of contractility. In 10 conscious dogs pretreated with morphine, norepinephrine at 5 micrograms/kg/min x 90 min produced similar changes to those seen in anesthetized animals. Ejection fraction was reduced from 0.69 +/- 0.3 to 0.36 +/- 0.04 at 60 min post infusion. Fractional shortening was also reduced. Left ventricular end-diastolic dimension was increased. However, when animals were followed for 1 week, complete recovery occurred within 48 h. Histology showed mild contraction band necrosis in acute experiments and mild perivascular fibrosis in chronic experiments. Therefore, norepinephrine cardiotoxicity produced significant left ventricular dilation and reduction of ejection phase indices of left ventricular function associated with reduced contractility. In chronic dogs, histologic changes were mild, and left ventricular dysfunction was reversible.

Anesthesia↗
PubMed1994

Natural vertical transmission of western equine encephalomyelitis virus in mosquitoes.

The mechanism by which western equine encephalomyelitis (WEE) virus and other mosquito-borne alphaviruses (Togaviridae) survive during periods of vector inactivity is unknown. Recently, three strains of WEE virus were isolated from adult Aedes dorsalis collected as larvae from a salt marsh in a coastal region of California. This provides evidence of vertical transmission of WEE virus in mosquitoes in nature. Vertical transmission in Ae. dorsalis and closely related mosquito species may be an important mechanism for the maintenance of WEE virus in temperate regions in North America where horizontal transmission of the virus is seasonal.

Aedes↗
PubMed1994

Electrocardiographic and segmental wall motion abnormalities in pancreatitis mimicking myocardial infarction.

Transient electrocardiographic changes in patients with acute cholecystitis, pancreatitis, and pneumonia have been reported in the past. These changes usually are in the form of T-wave inversion, ST-segment depression, and rarely ST-segment elevation in the absence of coronary artery disease. To the authors' knowledge, this is the first report documenting both left ventricular segmental wall motion abnormality and electrocardiographic changes of myocardial injury in the presence of acute pancreatitis.

Acute Disease↗
PubMed1994

The relations between cervical cancer and serological markers of nutritional status.

We evaluated whether differences in serological nutrient indicators between cases and controls were likely to be due to different usual levels for cases or to altered metabolism due to disease. Blood samples obtained as part of a case-control study of invasive cervical cancer conducted in Latin America were evaluated for case-control differences and for trends with stage of disease. Serum alpha- and beta-carotene, cryptoxanthin, and alpha- and gamma-tocopherol showed no trend with extent of disease, although Stage IV cases had lower alpha- and beta-carotene values than did other cases. A slight trend of decreasing values with stage was observed for serum retinol, lycopene, and lutein. For cholesterol and triglyceride concentrations, an inverse trend was observed with stage of disease, which suggested a clinical effect of the disease on blood lipids. Adjustment for smoking, alcohol intake, or oral contraceptive use did not alter observed relations, nor was there evidence that the altered blood nutrient levels differed by histological type. These data suggest that serum values for some carotenoids from Stage I, II, and III cervical cancer are suitable for etiological studies, but spurious results may be obtained if late-stage cases are included. Evidence of trends with severity of disease for cholesterol and triglycerides, and possibly for retinol, lycopene, and lutein, suggest that special attention be given to disease effects of these nutrients in studies of cervical cancer.

Adult↗
PubMed1994

A longitudinal study of human papillomavirus DNA detection in human immunodeficiency virus type 1-seropositive and -seronegative women.

Cericovaginal lavage samples from 124 human immunodeficiency virus type 1 (HIV-1)-seropositive and 126 HIV-1-seronegative women were collected monthly for 8 months and tested for human papillomavirus (HPV) DNA. The estimated prevalence of HPV was 42.8% in HIV-1-seropositive and 13.4% in -seronegative women (P < .001). There was no significant difference in HPV DNA detection in HIV-1-seropositive women with CD4 cell counts of < 300/mm3 (50% HPV-positive), 300-499/mm3 (36.4% HPV-positive), or > or = to 500/mm3 (40.5% HIV-positive). However, HIV-1-seropositive women who were more immunocompromised, as indicated by lower CD4 cell counts, were more likely to shed HPV persistently. The quantity of HPV DNA detected in cervicovaginal lavage samples was similar in HIV-1-seropositive and -seronegative women. This study further defined the characteristics of HPV infections in HIV-1-infected women.

Cervix Uteri↗
PubMed1994

Risk factors for genital papillomavirus infection in populations at high and low risk for cervical cancer.

This study sought to determine risk factors for genital infection with papillomavirus (HPV) in Panamanian women 20-49 years old. Subjects were randomly selected from Herrera and Panama provinces (cervical cancer incidence 79 and 25/100,000, respectively). Participants were interviewed to determine sexual behavior. Cervicovaginal lavage specimens were obtained to test for HPV DNA by commercial dot blot hybridization. HPV-16/18 DNA was detected significantly more frequently (5%) in Panama than Herrera (2%) samples (P = .002). Clearly, infection with high-risk HPV types alone cannot account for the differences in cervical cancer incidence between the two populations. HPV-16/18 detection decreased with increasing years of sexual experience among all women in Panama and among women with multiple partners in Herrera. However, HPV-16/18 detection did not change with sexual experience among monogamous women in Herrera. Thus, the epidemiology of HPV is complex and reflects both virus- and population-specific factors.

Adult↗
PubMed1994

Potential effect of global warming on mosquito-borne arboviruses.

If global warming occurs in California, daily mean temperatures may increase by 3 to 5 degrees C, precipitation patterns will change, and sea level may rise 1 m. Studies were done on effect of temperature changes on survival of Culex tarsalis Coquillett, the primary vector of western equine encephalomyelitis (WEE) and St. Louis encephalitis (SLE) viruses, in two regions where temperatures differed by 5 degrees C. Daily mortality of adult vectors increased by 1% for each 1 degree C increase in temperature. At 25 degrees C, only 5% of Cx. tarsalis survived for 8 or more days, the time required for extrinsic incubation of these viruses. Extrinsic incubation times for these viruses shortened when temperatures were increased from 18 to 25 degrees C. WEE virus infection was modulated and transmission decreased at 32 degrees C. If temperatures in the warmer region increase by 5 degrees C, WEE virus may disappear and SLE virus would persist. In the cooler region, a 5 degrees C increase would decrease vector survivorship and virus activity in midsummer. In North America, epidemics of WEE have prevailed above a 21 degrees C isotherm and those of SLE below this isotherm. With global warming, epidemics of these viruses could extend into currently unreceptive northern areas. WEE virus would disappear from more southern regions. Geographic distribution of vector, human, and animal populations could be altered. North America could become more receptive to invasion by tropical vectors and diseases.

Animals↗
PubMed1994

Tl-201 liver uptake for assessment of jeopardized myocardium during dipyridamole stress testing.

The current study was conducted to determine the significance of Tl-201 liver activity during 4 minute dipyridamole (DP) stress testing. Two groups of subjects were examined: group I subjects (n = 52) had electrocardiographic evidence of left ventricular hypertrophy (ECG-LVH), and group II subjects (n = 114) had no ECG-LVH. Both groups were further divided into four subgroups on the basis of Tl-201 myocardial perfusion scans: 1) no myocardial perfusion defect; 2) transient myocardial perfusion defect; 3) fixed myocardial perfusion defect; and 4) transient plus fixed myocardial perfusion defects. Tl-201 liver, heart, and lung activities were quantified in the immediate anterior planar images. Left ventricular mass was quantified using tomographic short-axis slices. In the no ECG-LVH group, Tl-201 lung-to-heart ratio was significantly increased in subjects having transient, fixed, and transient plus fixed myocardial perfusion defects when compared to no myocardial perfusion defect. Tl-201 lung-to-heart ratio did not increase in the ECG-LVH group of subjects having transient, fixed, and transient plus fixed myocardial perfusion defects. In contrast, Tl-201 liver-to-heart ratio increased in both the ECG-LVH and no ECG-LVH groups of subjects having myocardial perfusion defects when compared to subjects having negative myocardial perfusion scan. Left ventricular mass was increased in ECG-LVH subjects when compared to no ECG-LVH subjects, which might have resulted in increased Tl-201 myocardial uptake and, hence, reduced Tl-201 lung-to-heart ratio in ECG-LVH subjects having myocardial perfusion defects.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

Exercise testing in patients with electrocardiographic evidence of left ventricular hypertrophy.

The purpose of this study was to determine the influence of left ventricular hypertrophy, based on electrocardiographic evidence, on the results of exercise thallium testing. Patients with electrocardiographic evidence of left ventricular hypertrophy (ECG-LVH) and suspected of having coronary artery disease underwent exercise thallium testing. Retrospective analysis of 107 consecutive patients with ECG-LVH showed transient myocardial perfusion defects (TMPD) in 12 (11%), indicative of myocardial ischemia; 12 (11%) had fixed myocardial perfusion defects (FMPD), indicative of probable myocardial infarction; 5 had TMPD plus FMPD (5%), and scan results for 78 were normal (73%). In patients with ECG-LVH, additional ST changes were observed in 76% and chest pain in 7% of patients with ECG-LVH. In a matched comparison group of 255 patients not prescreened for ECG-LVH, TMPD was observed in 20%, FMPD in 16%, and TMPD plus FMPD in 26% of patients, and normal results were found in 38%. Electrocardiographic changes were found in 49% and chest pain in 20%. Hemodynamic responses to exercise were comparable between subgroups. Lung thallium uptake was quantified as the lung-to-heart thallium activity ratio (L-H) on the immediate exercise anterior planar images. In controls, a significant increase in L-H was observed in patients with TMPD and TMPD plus FMPD. This was not observed in patients with ECG-LVH, possibly because of elevated thallium myocardial activity as a result of increased left ventricular mass. The conclusion is that patients with ECG-LVH often had normal perfusion scan results (73%) on exercise despite a high incidence of additional ECG changes (76%).(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Disease↗