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Biomedical subjects

C G Hayes

Publications and source records attributed to C G Hayes.

At least 55 records · Page 3Linked to original sources
PubMed1994

Evidence for anti-Plasmodium falciparum antibodies that cross-react with human T-lymphotropic virus type I proteins in a population in Irian Jaya, Indonesia.

This study was performed to demonstrate the presence of anti-Plasmodium falciparum antibodies in a population living in Irian Jaya, Indonesia that cross-react with human T-lymphotropic virus type I (HTLV-I) proteins. Serum samples from 63 volunteers living in Oksibil, a secluded highland valley in Irian Jaya, were tested for anti-P. falciparum antibodies by an immunofluorescence assay and for anti-HTLV-I antibodies by an enzyme immunoassay (EIA). All samples were positive for anti-P. falciparum antibodies at titers of > or = 1:256. Twenty-four samples were reactive by EIA for HTLV-I, and of these, 23 were tested by western blotting (immunoblotting). Five of the 23 samples were classified as western blot positive and 18 were classified as western blot indeterminate. In competitive blocking assays with malaria proteins, western blot immunoreactivity to all HTLV-I Gag proteins was either reduced or eliminated. Significant reductions in the HTLV-I EIA optical density values of the Oksibil sera occurred when the sera were competitively blocked with the malaria antigens. The optical density values of HTLV-I-positive control sera showed no significant change. Competitive blocking with HTLV-I antigens produced reductions in the optical density values of both the Oksibil sera and the HTLV-I-positive control sera. These data suggest that in this population, anti-P. falciparum antibodies are cross-reactive with HTLV-I proteins in the western blot and EIA tests.

Animals↗
PubMed1994

Isolation of HIV-1 from Filipino commercial sex workers (CSWs).

Peripheral blood mononuclear cells (PBMC) from 36 HIV-1 antibody positive Filipino female commercial sex workers (CSWs) were co-cultivated at a 1:1 ratio with phytohemagglutinin-P activated PBMC from healthy, HIV-1 antibody negative donors. After 3-18 (mean 7.2) days of incubation at 37 degrees C in 5% CO2, 29 cultures showed evidence of replication of HIV-1: increasing concentrations of p24 antigen in the growth medium and the appearance of multinucleated giant cells. Although the length of incubation required for the appearance of cytopathogenic effect for each particular isolate was essentially the same when either 6 microwell plates were seeded with 3.0 x 10(6) cells/well or 24 well plates were seeded with 1.5 x 10(6) cells/well, the 24 well format was more sensitive. The ability to isolate HIV-1 from PBMC did not appear to be associated with the progression of disease or the presence or absence of any specific clinical findings. However, if the PBMC were from individuals with a concomitant p24 antigenemia, the incubation time required for isolation was significantly shorter (mean 3.8 days). The absolute CD4+ lymphocyte count was also slightly reduced in the culture positive, p24 antigenemic patients (range 302-813 cells/mm3, mean 502 cells/mm3) compared to the culture positive, p24 serum negative cases (range 311-1,511 cells/mm3, mean 830 cells/mm3). The p24 serum negative cases with CD4+ counts of < 500 cells/mm3 had positive PBMC cultures by 6 days of incubation.(ABSTRACT TRUNCATED AT 250 WORDS)

AIDS Serodiagnosis↗
PubMed1994

Natural history of HIV infection in Filipino female commercial sex workers.

A prospective follow-up study of the progression of HIV infection, from seroconversion to onset of opportunistic infections (OI) indicative of immune deficiency and to death, was performed in a cohort of 54 HIV-1 antibody positive Filipino female commercial sex workers (FCSW). The cumulative probability of having a CD4+ T cell count of < 200/mm3 and/or an OI indicative of severe immune deficiency was 52.9% within 5 years and 73.8% within 6 years after seroconversion. The cumulative probability of death was 52.1% within 6.5 years following seroconversion and 52.7% within 1.5 years after a depressed (< 200/mm3) CD4+ T cell or onset of an OI. Although several OI associated with immune impairment were observed, a CD4+ cell count of < 200/mm3 was the initial indicator of a failing immune system in more than 50% of the patients. Mycobacterium tuberculosis or unidentified acid fast bacilli (presumed to be M. tuberculosis) and Pneumocystis carinii pneumonia were the initial indicators of immune deficiency in the remaining patients.

AIDS-Related Complex↗
PubMed1993

U.S. Environmental Protection Agency's Ozone Epidemiology Research Program: a strategy for assessing the effects of ambient ozone exposure upon morbidity in exposed populations.

The Clean Air Act Amendments of 1990 mandate a future reduction of ambient ozone levels in many areas of the country, the cost of which will be great. In order to assess the current public health burden of ambient ozone exposure and to provide information for assessment of potential health benefits of improved air quality, the Health Effects Research Laboratory of the U.S. EPA has undertaken an Ozone Epidemiology Research Program. The research strategy which will guide this scientific program is described in this paper. Criteria for selection of important research questions as well as issues which cut across all questions and study designs are discussed. In particular, this program emphasizes the study of effects which reflect morbidity in the population. The three questions identified as being of most immediate importance involve the relationship of short-term ambient ozone exposure to acute respiratory illness, the relationship of recurrent exposure to chronic respiratory disease, and the relationship of recurrent exposure to development of acute respiratory illness. Specific research approaches and initial projects to address these three questions are described.

Animals↗
PubMed1993

Detection of West Nile virus by the polymerase chain reaction and analysis of nucleotide sequence variation.

A polymerase chain reaction (PCR) assay was developed to rapidly detect and identify West Nile (WN) virus. The RNA from seven isolates of WN virus from six countries and four other flaviviruses (Kunjin, Japanese encephalitis, St. Louis encephalitis, and yellow fever viruses) was reverse-transcribed (RT) and amplified by PCR. The nucleotide sequences of the amplified products were determined by a rapid, automated DNA sequencing method. The WN virus RT/PCR assay detected the target gene segment of sequencing method. The WN virus RT/PCR assay detected the target gene segment of isolates from both the African-Middle Eastern group and the Indian group with a sensitivity of approximately 0.05 pg of viral RNA. Kunjin virus was the only other flavivirus tested that produced a band of the appropriate size. Five of seven WN virus isolates showed 92-98% homology in the nucleotide sequence of their PCR products. The sequence of one isolate was virtually identical to the published sequence of the Nigerian isolate (99.5% homology). No correlation was established between the degree of nucleotide homology, geographic location, time of isolation, or source of the isolates.

Amino Acid Sequence↗
PubMed1993

Vertical transmission of West Nile virus by Culex and Aedes species mosquitoes.

Experiments were conducted to determine whether West Nile (WN) virus was transmitted vertically by colonized strains of Aedes albopictus, Ae. aegypti, and Culex tritaeniorhynchus. Female mosquitoes were infected by intrathoracic inoculation with WN virus, and the F1 progeny were tested for virus by the fluorescence antibody technique and the newborn mouse assay. Each of the three mosquito species transmitted WN virus to F1 adults derived from immature forms reared at 26 degrees C. The minimal filial infection rate (MFIR) ranged from 1:124 to 1:138 for Ae. albopictus, from 1:62 to 1:172 for Ae. aegypti, and from 1:325 to 1:859 for Cx. tritaeniorhynchus. The MFIR for Cx. tritaeniorhynchus reared at 20 degrees C was 1:213 for larvae and 1:390 for pupae, and 1:208 for larvae and 1:554 for pupae reared at 26 degrees C. These data are the first reported evidence of vertical transmission of WN virus by mosquitoes, and therefore warrant further studies to determine whether vertical transmission occurs among WN viral-infected mosquitoes in nature.

Aedes↗
PubMed1993

Ecology of mosquitos (Diptera: Culicidae) at a site endemic with Japanese encephalitis on Luzon, Republic of the Philippines.

A 2-year study of the ecology of mosquitos was conducted in a rice-growing area in the Philippines. Forty-four species in 8 genera were collected using 6 techniques, with Culex vishnui being most abundant. Of all the Anopheles collected, most species were exophagic, while most of the Culex species collected were endophagic. Anthropophilic or zoophilic feeding patterns were estimated using man-to-animal biting ratios. Peak periods of mosquito abundance occurred several months after the onset of both the rainy season and the rice irrigation period. Seasonal populations of the more abundant species revealed 3 distinct patterns: 1) populations are high during the rainy season and low during the irrigation period; 2) populations are equally strong during both periods; and 3) populations are highest during the irrigation period. Species' biting activity was grouped into 2 patterns: 1) those that feed primarily from 1800-0000; and 2) those that feed evenly throughout the night. Mosquito abundance and Japanese encephalitis virus activity were related to rainfall and rice-growing practices.

Animals↗
PubMed1992

Outbreak of fatal illness among captive macaques in the Philippines caused by an Ebola-related filovirus.

Following the detection of an Ebola-like virus in cynomolgus macaques recently imported into the United States from The Philippines, studies were initiated to document transmission at export facilities located in the latter country. At one export facility, 52.8% of 161 monkeys that died over a 2.5-month period were shown to be infected with this virus using an enzyme-linked immunosorbent assay to detect antigen in liver homogenates. A case fatality rate of 82.4% was documented for the infected monkeys. The initial anti-viral antibody prevalence among the captive macaques at this facility was 25.9% (indirect fluorescent antibody titer greater than or equal to 1:16). Followup documented infection of 24.4% of initially seronegative animals and 8.7% of initially seropositive monkeys. Being held in a gang cage versus a single cage was found to be a significant risk factor for subsequent virus infection, and the presence of IFA antibody was shown to predict protection. This study documents unequivocally for the first time the presence of an Ebola-related filovirus in Asia.

Animals↗
PubMed1991

Antibodies to human T lymphotropic virus type I in a population from the Philippines: evidence for cross-reactivity with Plasmodium falciparum.

Residents of two areas in the Philippines were tested for human T lymphotropic virus type I (HTLV-I): Napsan, a site endemic for malaria, and a nonmalarious site, Bacolod. By ELISA, 30% of the 1743 Napsan residents were positive. Western blot immunoreactivity with two or more HTLV-I proteins was present in 81% of the ELISA positives; however, there was no reactivity with the env proteins. The frequency of this indeterminate immunoreactivity increased with the malaria antibody titer. None of the 200 Bacolod sera were Western blot immunoreactive. In competitive serologic assays, an HTLV-I lysate blocked the HTLV-I immunoreactivity of the Napsan sera but did not reduce malaria antibody. A Plasmodium falciparum lysate blocked both the HTLV-I and malaria immunoreactivity of the Napsan sera. These results show that indeterminate HTLV-I immunoreactivity can be caused by P. falciparum antibody. Serosurveys conducted in malaria endemic areas should consider this possibility.

Animals↗
PubMed1991

Experimental studies to determine the susceptibility to infection with St. Louis encephalitis virus of five species of Panamanian mosquitoes.

The susceptibility to infection with a Panamanian isolate of St. Louis encephalitis (SLE) virus was evaluated in Culex quinquefasciatus, Haemagogus equinus, Mansonia dyari, Sabethes cyaneus and Deinocerites pseudes. When fed on blood-virus suspensions using the hanging drop or pledget technique, the median infective dose (ID50) of SLE virus for colonized strains of Cx. quinquefasciatus and Hg. equinus was 10(2.8) plaque forming units (PFU)/2 microliters and 10(3.5) PFU/2 microliters, respectively. The susceptibility of F1 and F2 Cx. quinquefasciatus females was similar to the colonized strain by the same technique. When fed on viremic chicks, the ID50 for both Cx. quinquefasciatus and Hg. equinus was 10(0.5) PFU/2 microliters. These results and successful transmission trials indicate that both of these species have the potential to serve as vectors of SLE virus in Panama. Because of their poor feeding response, complete susceptibility profiles were not obtained for the other 3 species tested. They appear to be less susceptible than Cx. quinquefasciatus and Hg. equinus, although Ma. dyari was readily infected after engorging on a blood-virus suspension with a titer of 10(3.0) PFU/2 microliters.

Animals↗
PubMed1991

HIV-1 seropositive women in the Philippines: pregnancy outcome and perinatal transmission of HIV-1.

Annual surveillance studies were initiated in 1985 to determine the incidence and prevalence of HIV-1 infection in female prostitutes registered through the Social Hygiene Clinic System of the Philippine Department of Health. All of the confirmed HIV-1 seropositive women detected in the above surveys who could be contacted were followed up about every three months to monitor their clinical and immunological status. Since we regularly interviewed and examined these HIV-1 seropositive women, we were able to note the occurrence of pregnancies following HIV diagnosis. By September 1990, 54 HIV-1 seropositive women (aged 18-35) detected from the above surveys had been interviewed and examined. Twenty-six of these HIV-1 positive women had a total of 37 pregnancies. Eight were pregnant at the time of HIV diagnosis: three term deliveries, one premature delivery (PD) at eight months, three abortions, and one lost to follow-up while still pregnant. Five of these eight had repeat pregnancies: two term deliveries, two abortions, and one lost to follow-up while pregnant. Eighteen other women became pregnant one or more times after HIV diagnosis: seven term deliveries, 13 abortions, two PDs, one ectopic pregnancy terminated, one currently pregnant, and one lost to follow-up during pregnancy. There was no clear indication from clinical examinations and CD4+ cell counts that pregnancy exacerbated the course of HIV-1 related disease in these women. One of the 12 term infants has died and eight have developed non-specific findings that are suggestive but not diagnostic of HIV infection.2+ strongly seropositive by both ELISA and Western blot assay at 16 months.

Adult↗
PubMed1991

Epidemic keratoconjunctivitis at a U.S. military base: Republic of the Philippines.

Between August 1988 and January 1989, 2,603 cases of acute conjunctivitis occurred at Clark Air Base in the Philippines. Clinical features of the disease were consistent with epidemic keratoconjunctivitis. Adenovirus types 19 and 8, as well as enteroviruses, were isolated from conjunctival swabs. Approximately 18% of 9,167 active duty personnel were affected. In an attempt to contain the outbreak, active cases were isolated from the workplace, resulting in 9,038 personnel-days lost. Military preparedness was significantly impacted. A case-control study revealed multiple risk factors for acquisition of the disease.

Adenovirus Infections, Human↗
PubMed1990

Sexual behavior of Filipino female prostitutes after diagnosis of HIV infection.

A study of female prostitutes in Manila who tested positive for human immunodeficiency virus (HIV) antibody ascertained demographic and sexual behavior information following diagnosis. Counselling alone did not appear to have a major impact on the sexual behavior of the HIV positive women since most continued to work as prostitutes. Switching from high risk to low risk jobs in bars is not effective in preventing HIV positive women from engaging in prostitution. Revoking work permits is only effective if enforced with adequate follow up. Alternative job training programs may offer a viable approach.

Contraceptive Devices, Male↗
PubMed1990

Epidemiology of HIV infection among prostitutes in the Philippines.

Between 1985 and 1987, examinations for human immune deficiency virus (HIV) antibody were done on 25,392 prostitutes working in 64 cities throughout the Philippines. The country-wide seropositivity rate among prostitutes based on this sample was 0.8/1,000. Of the HIV cases, 85% were working in just two cities whose prostitute populations comprised 50% of the total sample. The average incidence rate for the same two cities after 1 year was 2.3/1,000. HIV antibody-positive women were enrolled in a case-control study to determine demographic and epidemiologic risk factors. This study involving 34 HIV-positive prostitutes and 61 randomly selected negative control prostitutes did not reveal any risk factors related to sexual or other types of behavior. A history of genital warts, a history of abnormal vaginal discharge, and cytomegalovirus antibody were significantly more frequent in the HIV-positive cases than in the controls; however, by logistic regression analysis, only an abnormal vaginal discharge was independently associated with HIV infection. Absence of any evidence of transmission by blood transfusion or i.v. drug abuse suggests that HIV was introduced by the heterosexual route.

Adult↗
PubMed1989

The use of intravenous gammaglobulin in dengue fever, a case report.

We managed a serologically documented case of dengue fever with thrombocytopenia with IV IgG. Acute and convalescent ELISA and HI titers indicated an acute dengue infection with a secondary response that clinically, and by laboratory parameters dramatically improved after IV IgG administration. The use of IV IgG in cases of thrombocytopenia associated with dengue has both theoretical advantages and disadvantages. IV IgG may have a role in the management of DHF/DSS because of the significant morbidity and mortality associated with DHF/DSS. A prospective randomized study should be developed to determine if IV IgG does indeed effect the course of thrombocytopenia in dengue infections.

Adolescent↗
PubMed1989

Central nervous system leptospirosis in the Philippines.

One hundred hospitalized patients in Manila, Philippines with aseptic meningoencephalitis were screened for leptospirosis. On the basis of a microscopic agglutination titer of 1:1,600 or greater, the diagnosis was made in five cases, yet in no instance had leptospirosis been included in the differential diagnosis on admission to the hospital. Four of the five patients first noted neurologic symptoms during the second week of illness; two patients presented with encephalitis, two with meningitis and the fifth with hemiparesis. No case was complicated by renal dysfunction or jaundice. By the time of discharge from the hospital, two patients had recovered completely and the other three had markedly improved. Our data show that leptospirosis is an important but overlooked cause of aseptic meningoencephalitis in the Philippines. This is probably also the case in other parts of the tropics where Leptospira interrogans infection remains a significant public health problem.

Adult↗