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Biomedical subjects

S Tharavanij

Publications and source records attributed to S Tharavanij.

At least 55 records · Page 3Linked to original sources
PubMed1985

Assessment of validity of counterimmunoelectrophoresis and ELISA in the routine diagnosis of amoebiasis.

Counterimmunoelectrophoresis (CIE) was used to detect antibodies against Entamoeba histolytica in 99 sera from amoebiasis suspected patients using antigens from the HK-9 and HT-12 strains of axenically cultivated E. histolytica. There was no significant difference of seropositive rates using antigens from these two strains suggesting the both strains were equally suitable for use in the routine CIE test for the diagnosis of amoebiasis. In comparison with ELISA, the CIE test was a little less sensitive than ELISA with per cent sensitivity of 93.5 and 100 respectively. Two amoebic liver abscess patients who were CIE negative were ELISA positive. The CIE seropositive rate was related to the period after onset of clinical symptoms with per cent positivity of 66.7, 93.3 and 100 when the sera were tested on less than or equal to 5, 6-10 and greater than or equal to 11 days of illnesses respectively.

Amebiasis↗
PubMed1985

Immunological evaluation of cell-mediated and humoral immunity in Thai patients with cerebral and non-cerebral Plasmodium falciparum malaria: I. Cutaneous delayed hypersensitivity, blood leukocytes and in vitro lymphocyte responses.

In Thai patients with acute P. falciparum malaria including cerebral cases, cell mediated immune functions were studied in vivo and in vitro. Initial cutaneous delayed reactions to phytohaemagglutinin and soluble protein antigens were negative in most cerebral malaria patients. No major alteration of the number of circulating T and B cells was observed. In lymphocytes cultures, proliferatives responses to lectins or protein antigens were generally found within normal ranges. This study shows a direct role of P. falciparum on the impairment of cell mediated immunity.

Adolescent↗
PubMed1985

Immunological evaluation of cell-mediated and humoral immunity in Thai patients with cerebral and non cerebral Plasmodium falciparum malaria: II. Evolution of serum levels of immunoglobulins, antimalarial antibodies, complement fractions and alpha interferon.

In Thai patients with Plasmodium falciparum malaria, IgG and IgM values were elevated, whereas IgA levels were within normal ranges. No association of Ig values with parasitaemia was noted. IFA-IgM antibody levels were lower in cerebral malaria (CM) than in the non cerebral malaria (NCM) group. IFA-IgG antibodies were present in all patients. The mean C3 and C4 values were similar among patients from the CM and NCM groups. Interferon like activity was detected in all CM and NCM patients, and no correlation was found with either antimalarial antibodies, complement or parasitaemia.

Antibody Formation↗
PubMed1985

Factors contributing to the development of cerebral malaria. II. Endotoxin.

Limulus amoebocyte lysate test (LALT) was used to detect endotoxin-like substances in the plasma of 15 patients with cerebral malaria, 28 patients with uncomplicated falciparum malaria and 30 healthy controls. On admission, 67% of cerebral malaria patients were positive, whereas only 21.4% of uncomplicated malaria patients and none of controls were positive. Among uncomplicated malaria cases, four of eight patients with parasitaemia over 90,000/mm3 were LALT positive whereas only two of 20 patients with parasitaemia of less than 90,000/mm3 were positive. A follow-up study in cerebral malaria patients showed some variation in LALT positivity rate from day to day (85.7% on day 1, 53.3% on day 3 and all negative on discharge from hospital). LALT positivity bore no relationship to gram negative bacteraemia. Leucocytosis and elevated serum enzymes were more frequently found in LALT-positive patients. Our results suggest that endotoxin (LALT positivity) of the plasma of malaria patients is derived from either the parasites themselves or from the gut. It relates to parasitaemia, leucocytosis and elevated serum enzymes, but not to the clinical syndrome of cerebral malaria.

Bilirubin↗
PubMed1984

Factors contributing to the development of cerebral malaria. I. Humoral immune responses.

Humoral immune responses to malaria were studied in 100 patients with cerebral malaria of whom 53 had added complications, 108 patients with acute malaria, and 100 blood donors. The methods employed were indirect hemagglutination (IHA), indirect fluorescent antibody (IFA), enzyme-linked immunosorbent assay (ELISA), and parasite growth inhibition (PGI) tests. Patients with cerebral malaria, especially those with complications, had histories of fewer attacks of malaria in the previous 5 years than did those with acute malaria, suggesting that the cerebral malaria patients were less immune. The combined cerebral malaria group (complicated and uncomplicated) did not show defective humoral immune responses, since the initial seronegative rate and the mean initial IHA and IFA antibody titers were not significantly different from those of acute malaria patients and the mean initial ELISA titer was even higher than that of the acute malaria group. Reduced humoral responses were found only in complicated cerebral malaria patients, as their mean initial IHA titer was lower and their IHA seronegative rate was higher than those in acute malaria patients and in the uncomplicated cerebral malaria group. The combined cerebral malaria group had greater PGI activity than that of acute malaria patients, but this increased activity was entirely due to the higher results obtained in the complicated cerebral malaria group. The increased PGI activity returned to normal after recovery. An IgG preparation from seven of eight of these sera failed to exert the growth inhibition effect. Factors other than IgG were therefore responsible for the inhibition of parasite growth.

Adolescent↗
PubMed1984

Inhibition of entry of Plasmodium falciparum and P. vivax sporozoites into cultured cells; an in vitro assay of protective antibodies.

Plasmodium falciparum and P. vivax sporozoites were observed to invade cultured human hepatoma cells in vitro. Monoclonal antibodies to the circumsporozoite (CS) protein of each of these malarial species blocked invasion. Inhibition was species-specific, but was independent of the geographic origin of each strain. Because these monoclonal antibodies have been shown to diminish or abolish sporozoite infectivity to susceptible primate hosts, it is suggested that inhibition of invasion of sporozoites (ISI) into cultured cells may represent in in vitro assay for protective antibodies. This was confirmed by the finding that serum taken from volunteers immune to sporozoite challenge also totally blocked sporozoite invasion. The ISI assay also detected naturally acquired invasive-neutralizing antibodies in areas endemic for malaria. This ISI assay may therefore be useful in determining the incidence of inhibitory anti-sporozoite antibodies in general populations, and allow the monitoring of the effect of an anti-malarial vaccine using sporozoite-derived antigens.

Adult↗
PubMed1984

A simple and rapid diagnostic test for typhoid fever.

Barber protein sensitized latex particles were used in the latex agglutination test for the diagnosis of typhoid fever and the result compared with that of Widal 'O' and 'H' agglutination test. The latex agglutination test was positive in all 20 bacteriologically proved typhoid patients, in 81 of 85 (95.3%) typhoid suspected patients, and only in 2 of 85 (2.3%) blood donors. In contrast, the positive rates were 60% for both 'O' and 'H' Widal agglutinations in bacteriologically proved typhoid patients, 34.2% and 71.7% respectively in typhoid suspected patients, and none of blood donors were positive. The sensitivity and specificity of the latex agglutination test were 100% and 97.6% respectively with positive and negative predictive values of 90.9% and 100% respectively. The latex agglutination test may be particularly useful for the presumptive diagnosis of typhoid fever in remote health centres.

Adolescent↗
PubMed1984

Infection rates of respiratory syncytial virus in pediatric patients attending Phra Mongkutklao Hospital, Bangkok.

Respiratory syncytial virus (RSV) and other pathogens were isolated from nasopharyngeal secretions from 200 pediatric patients attending the Out Patient Department of Phra Mongkutklao Hospital with symptoms of upper respiratory tract infections. Their sera were also taken for determination of class specific immunoglobulin antibody titers. The positive isolation rates were 36% for RSV, 5.5% for adenovirus 1.5% for herpes simplex virus (HSV), and 4% for Staphylococcus aureus. One to 5.5% of these patients had mixed infection. Ninety five percent of patients with positive RSV isolations had IgM antibody which was found only in 30.7% in patients with negative RSV isolations. This result indicated that RSV was likely to be the most common pathogen responsible for the upper respiratory tract infections in children in Bangkok during the rainy season.

Adolescent↗
PubMed1983

Impaired cell-mediated immunity in Plasmodium falciparum-infected patients with high-parasitemia and cerebral malaria.

Several cell-mediated functions were studied in vivo and in vitro in 63 Thai patients with acute falciparum malaria, including 21 cases with cerebral manifestations and 10 cases with initial parasitemia over 10%. Initial delayed cutaneous reactions to phytohemagglutinin and soluble protein antigens were negative in most cerebral malaria cases. In other patients, skin reactions were impaired or abolished as a direct function of parasitemia. No major alteration in the numbers of blood T and B lymphocytes was found. In lymphocyte cultures, proliferative responses to lectins were generally found within normal ranges; in contrast, proliferative responses to candidin were suppressed in parallel with delayed cutaneous responses to the same antigen. From these data, it can be concluded that the alteration of specific cell-mediated responses are predominantly detectable in acute cases with major parasite invasion, i.e., high parasitemia and/or cerebral manifestations. A direct role of Plasmodium falciparum was further suggested by the rapid restoration of cell-mediated functions observed in several cases under successful antimalarial therapy. These results do not support any evidence in favor of a preexisting cellular immune deficiency in relation with the occurrence of cerebral or high-parasitemia acute malaria in these patients.

Acute Disease↗
PubMed1983

Preliminary field trial of a radioimmunoassay for the diagnosis of malaria.

A radioimmunoassay (RIA) has been developed for the detection of Plasmodium falciparum in infected blood. The assay is based on the ability of solubilized, infected red blood cells (RBC) (P. falciparum "antigen") to combine with anti-P. falciparum antibodies and thus prevent the subsequent interaction of the latter with "antigen"-coated microtiter plates. A preliminary trial was carried out in Thailand to determine the usefulness of the RIA for the immunodiagnosis of malaria. Blood samples from malarious and non-malarious patients were examined both by standard microscopy and by RIA. Efficient solubilization of the parasites proved to be a major requirement for the successful performance of the RIA. Sonication or freezing and thawing, which were perfectly satisfactory for the solubilization of cultured, infected RBC, were found to be totally inadequate when applied to RBC taken from patients. However, parasites in RBC from patients could be solubilized efficiently by treatment with detergents (e.g., NP40, Triton X-100, etc.). Of the 108 blood samples tested, 23 were found positive for falciparum parasitemia by microscopy and 39 by RIA. One sample from a patient with patent falciparum parasitemia and three with patent vivax parasitemia were negative by RIA. Ten of the samples positive only by RIA belonged to patients with recent malarial infection, as shown by microscopy. Thus, the RIA detected almost all of the patients with microscopic evidence of falciparum malaria. The proportion of false positives in the RIA test was low.

Detergents↗
PubMed1983

Anti-sporozoite antibodies induced by natural infection.

Serum samples from 120 individuals living in a malaria-endemic area, 31 patients with Plasmodium falciparum infection, and 58 healthy blood donors were tested for antibodies against P. falciparum and P. vivax sporozoites. Specific antibodies were determined by the circumsporozoite precipitation (CSP) reaction and indirect immunofluorescent (IFA) tests for IgG and IgM antibodies. It was found that a high proportion of adults living in the endemic area had IFA anti-sporozoite antibodies, usually IgG. Children and healthy donors were either negative or had low antibody titers. A positive correlation was found between IgG antibody titers against P. falciparum sporozoites and those against P. vivax sporozoites. CSP reactivity was demonstrated in 5 of 31 sera from patients with falciparum malaria, and was always associated with a high level of IFA antibodies. The anti-sporozoite antibodies were found to be stage- and species-specific.

Adolescent↗
PubMed1983

Serum alpha-1 antichymotrypsin is a possible growth inhibitor of Plasmodium falciparum.

Serum protease inhibitors were determined in paired sera from 7 patients with cerebral malaria and 2 patients with acute malaria showing high and low growth inhibition activity in the initial and follow-up sera respectively. Alpha-1 antichymotrypsin and alpha-1 antitrypsin but not alpha-2 macroglobulin showed direct correlation with the growth inhibition activity. When alpha-1 antitrypsin was deliberately added to the malarial culture no growth inhibition occurred indicating that the alpha-1 antichymotrypsin was the most likely factor responsible for inhibition of growth of malarial parasites in vitro.

Chymotrypsin↗
PubMed1983

Herpes simplex virus and genital infections in Thai pregnant women.

Vaginal swabs were collected monthly from 100 asymptomatic Thai pregnant women as well as from 11 pregnant women with herpetic lesions of the vulva for isolations of HVH, mycoplasma and gonorrhoea. In asymptomatic mothers, 25% and 21% of cases were positive for HVH and mycoplasma respectively. Mixed infections of HVH and mycoplasma, and HVH and gonorrhoea were also found in 27% and 1% of cases respectively. Follow-up in asymptomatic pregnant women and those with herpetic lesions showed positive HVH fluctuations throughout the course of study. Positive HVH was recovered from 48% of amniotic fluid and 32% of breast milk of asymptomatic pregnant women with positive HVH genital isolates, and in 72.7% of aminotic fluid and 36.4% of breast milk in patients with herpetic lesions. HVH was also isolated from 84% of infants of asymptomatic mothers positive for HVH, and 100% of patients with herpetic ulcer. HVH was isolated most frequently from the throat and also from nose, eyes, and ears but with less frequency. IgM antibodies were found in three infants born of asymptomatic mother and in one infant of a mother with herpetic lesion. The low percentage of IgM antibody was interpreted to mean that the HVH isolated from the newborn infants were acquired during passage through the birth canal.

Amniotic Fluid↗