Biomedical subjects

R Tan

Publications and source records attributed to R Tan.

At least 91 records · Page 5Linked to original sources

PubMed1985

Isolation of Japanese encephalitis virus from Anopheles annularis and Anopheles vagus in Lombok, Indonesia.

Three strains of Japanese encephalitis (JE) virus were recorded from mosquitoes collected in Lombok, Indonesia, during March 1979, from pools of Anopheles vagus, An. annularis and Culex tritaeniorhynchus respectively. This is believed to be the first report of isolation of JE virus from An. vagus. The frequencies of JE viral infection in zoophilic Anopheles species were higher than in Cx tritaeniorhynchus, the principle vector of JE virus in Asia. The low frequency of infection in Cx tritaeniorhynchus and the relatively infrequent raising of pigs may account for the low prevalence of JE neutralizing antibodies in the human populations of Lombok.

Animals↗

PubMed1985

Correlation of population indices of female Culex tritaeniorhynchus with Japanese encephalitis viral activity in Kapuk, Indonesia.

Nineteen consecutive monthly light trap collections of mosquitoes were made between October 1978 and April 1980 in Kapuk, Indonesia. Kapuk is a small suburb of Jakarta where pigs are raised in close proximity to rice paddies which are breeding sites for Culex tritaeniorhynchus. Japanese encephalitis (JE) virus is believed to be endemic and has been recovered from mosquitoes and pigs in the area on several occasions. A total of 18,435 female Cx. tritaeniorhynchus were allocated to 359 pools of approximately 50 per pool. Virus isolations were attempted in both Vero and BHK-21 cells and agents producing cytopathic effect were identified in a micro-neutralization test. Nineteen strains of JE were recovered from the 359 pools of Cx. tritaeniorhynchus tested. The light trap index of female Cx. tritaeniorhynchus (X) and the relative frequency of pools positive for JE (Y) for each month of the study were plotted and correlation coefficients (r) calculated after transforming the mosquito population data logarithmically and the relative frequencies of isolation by arcsine square root. The close fit of the data (p less than 0.001) to an inverse linear model (1/y = a + b log10X) suggests a close dependence of JE viral activity on the population dynamics of Cx. tritaeniorhynchus. Three additional strains of JE were recovered from other Culex spp. at the same study site. One strain each was isolated from individual pools of Cx. gelidus, Cx. vishnui and Cx. fuscocephala. Cx. tritaeniorhynchus was more frequently infected with JE than the other species tested.

Culex↗

PubMed1984

Phenol red as volume marker in rat stomach with mucosal damage.

Phenol red, long considered an acceptable volume marker in gastrointestinal experiments, has been tested in rat stomach damaged by exposure to aspirin. Significantly more phenol red was lost from stomachs damaged by aspirin than from control stomachs. Phenol red, therefore, should not be used as a volume marker in damaged stomachs. Volumes of fluid in the stomachs, which increased during the experiment, were calculated from inulin concentrations. Changes in volume of stomach fluid in experimental animals were not significantly different from those in controls.

Animals↗

PubMed1984

Are elevated serum amyloid A levels and amyloid-enhancing factor sufficient to induce inflammation-associated amyloid deposition?

During inflammation-associated amyloidosis two coincident factors, serum amyloid A (SAA) and amyloid-enhancing factor (AEF) are apparently necessary for amyloid A (AA) deposition. It is shown by passive transfer of cytokines, which stimulate SAA production, and AEF that these are not sufficient. A further factor(s) is necessary, which stems from the acute inflammatory response. Potential candidates are serum or tissue glycosaminoglycans.

Amyloidosis↗

PubMed1981

Estimate of the risk of post transfusion hepatitis B in Jakarta, Indonesia.

The prevalences of hepatitis B surface antigen (HBsAg) and antibody to HBsAg (anti-HBs) were determined in blood donors and transfusion recipients in Jakarta, Indonesia. In blood donors the prevalence of HBsAg was 10% while anti-HBs was 43%. In transfusion recipients the prevalence of HBsAg and anti-HBs was 67%. The prevalence of susceptible recipients or those without detectable HBsAg or anti-HBs was 33%. Thus, the probability that a susceptible recipient would receive HBsAg from a blood donor was calculated at 3.3%. Published data from other studies were used to estimate the risk of clinical post transfusion hepatitis in Jakarta at between 0% and 2%.

Adolescent↗

PubMed1981

Viraemia in patients with naturally acquired dengue infection.

The magnitude and duration of dengue viraemia were studied in 153 patients with naturally acquired dengue infection in Jakarta, Indonesia. The duration of viraemia ranged from 2 to 12 days, but most patients had detectable circulating virus for 4-5 days. Accurate measurement of peak virus titres was not possible for many patients because of late admission to the hospital. Composite pictures of viraemia for each serotype, however, showed that many patients infected with dengue 1, 2, or 3 had circulating virus titres ranging from barely detectable to over 10(8) MID(50) per ml for 3-5 days. Virus titres in patients infected with dengue 4 were about 100-fold lower. Dengue haemagglutination-inhibition antibody titres of 80 or less had little effect on viraemia, but antibody titres of 160 or greater were associated with a decrease in virus isolation rate and in virus titre. The duration and magnitude of viraemia did not vary significantly with the severity of the disease and was only slightly higher in patients classified as primary dengue infections than in those classified as secondary infections. Measurement of viraemia in fatal dengue haemorrhagic fever (DHF) cases showed that these patients had significant quantities of circulating virus at the time of death.

Dengue↗

PubMed1981

Comparative sensitivity of mosquito inoculation and mammalian cell culture for isolation of some arboviruses in Indonesia.

The sensitivity of parenteral inoculation of colony reared male Aedes aegypti and mammalian cell cultures for isolation of Japanese encephalitis virus and dengue virus were compared. The mosquito inoculation technique proved to be more sensitive for the isolation of dengue virus from the sera of febrile patients than did the mammalian cell cultures (Vero and BHK21) employed in these studies. Mosquito inoculation proved to be no more sensitive that the mammalian system for the isolation of Japanese encephalitis virus from field caught female mosquitoes.

Aedes↗

PubMed1979

The twin transfusion syndrome. Clinical observations on 35 affected pairs.

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Acute Disease↗

PubMed1979

Variation in susceptibility to oral infection with dengue viruses among geographic strains of Aedes aegypti.

The comparative susceptibility of 13 geographic strains of Aedes aegypti to oral infection with dengue viruses was studied by feeding the mosquitoes on a virus-erythrocyte-sugar suspension. Significant variation in susceptibility to four dengue serotypes was observed among the geographic strains tested. Mosquito strains which were more susceptible to one serotype were also more susceptible to the other serotypes, suggesting that the factors controlling susceptibility were the same for all types. The amount of virus required to infect mosquitoes orally varied inversely with the susceptibility of the geographic strain. Thresholds of infection were not the same for dengue types 1, 2, 3 and 4. There was no apparent difference in infectivity between prototype and recently isolated strains of dengue types 1 and 3. Crossing experimentibility as the resistant parent. No difference was observed between resistant and susceptible mosquito strains in the rate or the amount of viral replication after infection by the parenteral route, or in their ability to transmit dengue 2 virus after infection by the oral route.

Aedes↗

PubMed1979

Dengue virus isolation in Indonesia, 1975-1978.

Virus isolations from dengue hemorrhagic fever patients in Indonesia are reported from 1975 to 1978. All 4 dengue serotypes were endemic in Jakarta, but dengue 3 was the predominant virus isolated. This type was also the most frequently isolated virus from patients outside Jakarta and had the widest distribution in Indonesia. The sensitivity of the mosquito inoculation technique for isolation of dengue viruses is discussed.

Antigens, Viral↗

PubMed1978

Immunologic parameters in childhood Hodgkin's disease II. T and B lymphocytes in the peripheral blood of normal children and in the spleen and peripheral blood of children with Hodgkin's disease.

A study of peripheral blood lymphocyte populations in 27 children with Hodgkin's disease (HD) and 13 age-matched control subjects is presented. The absolute numbers and percentages of T and B lymphocytes identified by their surface marker characteristics were determined. In addition, in 13 HD children the percentages of T and B lymphocytes were estimated in the spleens removed at staging laparotomy. No differences were observed between the total peripheral blood lymphocyte counts of HD and control children, and we found no evidence of progressive lymphopenia with advancing stages of the disease. No decrease in the numbers of peripheral blood T lymphocytes was seen in this group of HD children. In contrast, the proportions and absolute numbers of B lymphocytes tended to be significantly lower in the children with HD than in the control subjects. In 9 of the 13 spleens studied high percentages of T lymphocytes were seen; low percentage of B lymphocytes were found in all spleens examined.

Adolescent↗

PubMed1978

In vitro responses of peripheral blood and spleen lymphoid cells to mitogens and antigens in childhood Hodgkin's disease.

Over the past 5 years, parameters of immunological function have been determined in all children with biopsy-proven Hodgkin's disease in the Department of Pediatrics, Memorial Sloan-Kettering Cancer Center. This report summarizes the in vitro responses of lymphocytes to stimulation by mitogens and antigens (between January 1975 and December 1976) in 33 of these previously untreated patients. In nine of these patients, responses of the splenic lymphocytes were studied concomitantly with the responses of peripheral blood lymphocytes. Peripheral blood from normal children and adults was used as the control. Our results have demonstrated no significant differences between the responses of normal children and adult controls. The absolute necessity for concomitant studies of the controls and the patients was shown. The value of examining multiple concentrations of a single mitogen was also well defined. In the children with Hodgkin's disease, there was a consistent failure of the peripheral blood lymphocytes to respond to the lower concentration dose of phytohemagglutinin. However, this abnormality was not found in the splenic lymphocytes.

Adolescent↗

PubMed1977