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Biomedical subjects

N Bhamarapravati

Publications and source records attributed to N Bhamarapravati.

At least 55 records · Page 3Linked to original sources
PubMed1987

Immunization with a live attenuated dengue-2-virus candidate vaccine (16681-PDK 53): clinical, immunological and biological responses in adult volunteers.

A live dengue-2 (DEN-2) candidate vaccine (strain 16681-PDK 53), attenuated by passage in primary dog kidney cells, was tested in ten adult volunteers for evaluation of the safety, infectivity and immunogenicity of a dose of 1.9-2.7 x 10(4) plaque-forming units. Five of the volunteers were nonimmune to either dengue or Japanese encephalitis (JE) viruses; the other five were nonimmune to dengue but immune to JE. After receiving 1.0 ml of the vaccine subcutaneously, all ten volunteers developed neutralizing antibodies to DEN-2 which were maintained for at least one and a half years. None of the subjects developed abnormal signs or symptoms and the results of clinical chemistry investigations were within normal range throughout the 21 days of observation after the immunization. Virus isolated from one viraemic volunteer retained the small-plaque and temperature-sensitive growth characteristics of the vaccine virus in vitro. Further testing of this candidate vaccine in humans is indicated.

Adolescent↗
PubMed1987

Neurovirulence effects of dengue-2 viruses on the rhesus (Macaca mulatta) brain and spinal cord.

Vaccines prepared from attenuated virus can cause symptomatic viral infection of the central nervous system. In the present study, dengue-2 parental and its live attenuated viruses were tested by intrathalamic and intraspinal injections in rhesus monkeys. The dengue-2 viruses were found to be only very weakly neurovirulent when injected directly into the brain or spinal cord of rhesus monkeys.

Animals↗
PubMed1986

Enhancing effects of rodent malaria on aflatoxin B1-induced hepatic neoplasia.

The interaction between aflatoxin and malaria was tested for its usefulness as a model for hepatic tumor induction in rats. Male Buffalo rats which received aflatoxin B1 (AFB1) followed by Plasmodium berghei infection developed more preneoplastic lesions in the liver compared to those given AFB1 alone. No preneoplastic lesions were found in the liver of control and malarial-treated animals. These findings suggest that the malarial parasite facilitates liver tumor development initiated by AFB1 in rats.

Aflatoxin B1↗
PubMed1986

Passive hemagglutination test for antibody to hepatitis B core antigen.

Available tests for antibody to hepatitis B core antigen (anti-HBc) are complicated. A passive hemagglutination assay for anti-HBc was developed by sensitizing sheep erythrocytes with hepatitis B core antigen synthesized by a recombinant DNA technique. It was compared with a commercial passive hemagglutination assay and an enzyme-linked immunosorbent assay for anti-HBc and showed good agreement with both. It is rapid, simple, and sensitive.

DNA, Recombinant↗
PubMed1986

Automated cytochemistry in non-Hodgkin's lymphoma: a new method for determination of cells from lymph node biopsy.

Cell suspension prepared from the lymph node biopsy of patients with non-Hodgkin's lymphoma (NHL), metastatic carcinoma (MC) and non-neoplastic lymphadenopathies (NL) were analyzed by the Hemalog D, automated differential counter. The preparation of lymph node cells is described first in this study. The results show that the percentage of large cells (diameter greater than 13.5 micron) stained negatively with peroxidase (LUC, large unstained cells) was remarkably increased in patients with NHL (mean +/- SEM = 18.6 +/- 3.1%) and was particularly increased in the subgroup, diffuse histiocytic type (31.1 +/- 5.3%). Patients with MC had a raised percentage of nonspecific esterase-positive cells (9.2 +/- 1.4%) compared to patients in the NHL and NL groups. Patients in the NL group had low percentages of both LUC (5.3 +/- 0.7%) and nonspecific esterase-positive cells (1.8 +/- 0.2%). Quantitation of cells in the lymph node by using the Hemalog D may assist in the diagnosis of lymph node diseases.

Biopsy↗
PubMed1986

Blood value changes in flavivirus-inoculated Macaca fascicularis monkeys.

Blood values were analysed in eighteen cynomolgus monkeys on pre-and post-neurovirulence testing of dengue-2 and yellow fever vaccine viruses, dengue-2 parental and Japanese encephalitis viruses. Certain changes between blood chemistry, hematology and serology were observed and briefly discussed.

Animals↗
PubMed1986

The neurovirulence of flaviviruses in crab-eating monkeys (Macaca fascicularis).

The neurovirulent properties of attenuated dengue-2 and yellow fever (YF) vaccines, dengue-2 (DEN-2) and Japanese encephalitis (JE) viruses were studied in crab-eating monkeys (Macaca fascicularis). Number of central nervous system sites (as proportion affected) with neurovirulence (NV) lesions were compared. The results indicate that these monkeys reliably developed NV-lesion when inoculated with either JE or YF vaccine viruses (87%). NV-lesions occurred in a minority when inoculated with DEN-2 vaccine virus, were of minimal severity (9%), were probably biologically insignificant, and were of equal or less severity than lesions produced by its parental virus (10%).

Animals↗
PubMed1985

Quantitative changes of red blood cell shapes in relation to clinical features in beta-thalassemia/HbE disease.

Quantitative analysis of red blood cell (RBC) shapes was performed in 79 patients with beta-thalassemia/HbE disease, using scanning electron microscopy (SEM). Most patients had many abnormal RBC shapes, namely: torocytes, codocytes, dacryocytes, keratocytes, and schizocytes with a reduction in the number of normally shaped red blood cells (discocytes). Splenectomy, larger splenic sizes, and increasing anemia all were associated with a further reduction in the number of discocytes, reflecting increasing numbers of abnormally shaped RBC. The number of torocytes was increased with anemia; a larger spleen was associated with a decrease and splenectomy with an increase in the number of torocytes, indicating that they are destroyed by the spleen. The numbers of codocytes and echinocytes were singularly associated with splenectomy. Most likely, almost all of the echinocytes are destroyed by the spleen. The red blood cell types that occur as a result of RBC fragmentation, namely, dacryocytes, keratocytes, and schizocytes, were remarkably associated with the splenic status; larger splenic size was associated with an increased number of these cells, while splenectomy was associated with a noticeable reduction in their numbers. This finding confirms the role of the spleen in the fragmentation of thalassemic RBC. An increasing degree of anemia did not affect the number of codocytes and echinocytes, but was associated with a mild increase in the number of fragmented RBC and a significant increase in the number of torocytes.

Erythrocyte Count↗
PubMed1985

Culturing of human hepatocellular carcinoma. A simple and reproducible method.

Eight permanent human hepatocellular carcinoma (HHC) cell lines were established from 8 individual patients by the use of aspirated needle biopsy specimens (smaller than 0.1 ml in size). The cells grew in clustered form and retained intercellular junctions and canaliculi resembling bile canaliculi. The presence of secreted human alpha-fetoprotein and human albumin was detected in the cultured medium. Hepatitis B surface (HBs) antigen was not found on these cells. Implantation of the cells into athymic mice was followed by the growth of hepatocellular carcinomas and the appearance of human alpha-fetoprotein in the mouse serum. Chromosome analysis of three of the cell lines showed hyperdiploidy in two of them and hypotetraploidy in the other. Enzyme analyses of culture medium and cell homogenates have detected some enzymes characteristic of liver tissue such as gamma-glutamyl transferase, sorbital dehydrogenase, alkaline phosphatase, glutamate dehydrogenase, as well as aspartate and alanine transaminase. These tumor cells have been continuously maintained in culture for over 6 years with no significant changes observed.

Albumins↗
PubMed1985

Precipitating antibodies to non-treated dengue type 2 viral antigens in sera of Thai hemorrhagic fever patients by crossed immunoelectrophoresis.

Crossed immunoelectrophoresis of dengue type 2 virus revealed at least two precipitating antigens which shared some antigenic determinants. Glycoprotein components of both antigens were detected by binding to concanavalin A. Sera from dengue hemorrhagic fever patients showed precipitating antibodies to both antigens which could be quantitated according to the precipitate patterns formed in the intermediate gel of crossed immunoelectrophoresis. All secondary dengue hemorrhagic fever patients demonstrated an increase in precipitin titers in convalescence sera. Most patients with mild illness contained precipitating antibodies in acute phase sera whereas severe cases did not. Convalescent sera from severe cases showed only low titers. These precipitating antibodies may be associated with protection since they were produced early only in those with mild form of illness.

Adolescent↗
PubMed1984

Crossed immunoelectrophoresis for the detection of split products of the third complement component in dengue hemorrhagic fever. II. In vitro activation by dengue viral antigen.

The ability of dengue viral antigen(s) from different sources, and performed antigen-antibody complexes, to activate the third component of human complement (C3) in vitro was demonstrated by using split products of human C3. Dengue type 2 viral antigen(s) from suckling mouse brain and from infected monocytes activated C3 via the alternative pathway, while performed soluble dengue-2 antibody complex activated mainly the classical pathway. The implications of this finding for the pathogenesis of dengue hemorrhagic fever are discussed.

Animals↗
PubMed1984

Absence of dengue 2 infection enhancement in human sera containing Japanese encephalitis antibodies.

Sera from 52 young adults resident in a rural area in North Thailand were studied for plaque-reducing neutralizing antibodies against dengue (DEN) viruses types 1-4 and Japanese encephalitis (JE), and for DEN-2 infection-enhancing antibodies using a newly described microtest in the human monocyte cell line, U-937. Infection-enhancing antibody titers in U-937 cells using a simplified micromethod were similar to results obtained by published methods using human peripheral blood leukocytes and a macrotest using U-937 cells. In the sample, there were 23 with antibodies to one or more DEN viruses with or without accompanying JE antibodies; 16 sera demonstrated antibodies only to JE and 13 had no detectable antibodies to any flavivirus. All but two DEN antibody-containing sera enhanced DEN-2 infections in U-937 cells, often to titers of 1:10,000 or greater. By contrast, only one of 16 JE-immune sera enhanced DEN-2 infection in monocytes, and that at a dilution of 1:100. None of the flavivirus-negative sera had DEN-2 enhancing activity. The failure of human anti-JE contrasts with the ability of rabbit anti-JE to enhance DEN-2 infections, but correlates with the absence of recorded instances of dengue shock syndrome in human beings sequentially infected with JE and then a DEN virus. This report seemingly reconciles in vitro and in vivo phenomena, and may provide an opportunity to study mechanisms involved.

Adult↗
PubMed1984

Application of peroxidase-antiperoxidase (PAP) staining for detection and localization of dengue-2 antigen. I. In an endogenous peroxidase containing cell systems.

The unlabelled immunoperoxidase, peroxidase-anti-peroxidase (PAP), technique was used to detect dengue type-2 viral antigen in several cell systems including the endogenous peroxidase containing cells. These cells are the mosquito cell line (C6/36), continuous cell line of rhesus monkey kidney (LLC-MK2), human monocyte culture both cell suspension and monolayer, and human peripheral blood leukocytes. All of these specimens gave the same results that dengue-2 viral antigen presented in cytoplasm only and the patterns of marker presentation in positive cells varied depending on the duration after infection. The sensitivity of this method is extremely high since it can detect dengue-2 antigen after its attachment on mosquito cells (15 min) as seen in experiments with mosquito cell line, C6/36. False positive was not observed in all cell systems tested.

Animals↗
PubMed1983

Different patterns of intraerythrocytic inclusion body distribution in the two types of haemoglobin H disease. An ultrastructural study.

Electron microscopic examination of intraerythrocytic inclusion bodies induced by methylene blue was carried out in 7 non-splenectomized patients with haemoglobin (Hb) H disease. In classical Hb H disease with the genotype of alpha-thalassaemia 1/alpha-thalassaemia 2 the inclusion bodies were mostly membrane-associated. In contrast, in Hb H disease of alpha-thalassaemia 1/Hb Constant Spring genotype the majority of inclusion bodies were in a floating stage. Possible mechanisms for the unexpected difference are discussed.

Erythrocyte Inclusions↗
PubMed1983

Crossed immunoelectrophoresis for the detection of split products of the third complement in dengue hemorrhagic fever. I. Observations in patients' plasma.

Crossed immunoelectrophoresis was applied to detect the products of the third component of complement (C3) activation in plasma of patients suffering from dengue hemorrhagic fever (DHF), using inulin-treated normal human sera as positive control. In DHF, C3 split products were demonstrated in severely ill patients classified as having Grade III and Grade IV disease. These split products rapidly disappeared during the convalescent phase. The appearance of C3 activation products in DHF correlated well with signs of shock. This electropherogram of C3 activation could be used as a parameter reflecting immunologic activity in dengue hemorrhagic fever.

Adolescent↗
PubMed1981

Enhancing effects of dimethylnitrosamine on aflatoxin B hepatocarcinogenesis in rats.

In a study of possible enhancing effects of dimethylnitrosamine (DMN) on aflatoxin B1 (AFB1) hepatocarcinogenesis, male Buffalo strain rats were fed diets containing 1 ppm AFB1, 25 ppm DMN, and a combination of 1 ppm AFB1 and 25 ppm DMN (AFB1 + DMN). The diets were replaced by chow pellets after 6 months, and animals were killed 3, 6, 9 and 12 months after the onset of the experiment. In the untreated control group animals were free of hepatocellular carcinoma but the treated groups fed AFB1, DMN and AFB1 plus DMN developed hepatic lesions ranging from multiple cysts, altered cell foci and neoplastic nodules to hepatocellular carcinomas. Hepatocellular carcinomas developed in 79%, 45% and 5% of rats fed AFB1 plus DMN, AFB1 and DMN respectively at the end of the experiment. Multiple cysts were also found in all periods in animals fed AFB1 plus DMN, whereas rats fed AFB1 and DMN separately developed a few multiple cysts by the end of the experiment. These findings suggest that DMN potentiates the hepatocarcinogenesis induced by AFB1 in rats.

Aflatoxin B1↗