Characterization of entamoeba histolytica antigens in circulating immune complexes in sera of patients with amoebiasis.

Isolated circulating immune complexes (CICs) from sera of patients with amoebiasis were characterized to determine Entamoeba histolytica antigens that participate in the disease process. In total, 116 serum samples were collected before starting anti-amoebic therapy, and their CICs were isolated by differential polyethylene glycol precipitation. The presence of amoeba-specific antigens in CICs was detected by antigen capture enzyme-linked immunosorbent assay (ELISA) and by immunoblot assay. Antigen capture ELISA showed significantly higher optical density (p < 0.001) in all patients with amoebiasis than in the normal healthy controls and patients of non-amoebic hepatic disorder. Immunoblot assay detected amoeba-specific CICs in all 18 patients (100%) with confirmed amoebic liver abscess, 28 (80%) of 35 patients with clinically-suspected amoebic liver abscess, and 18 (78.26%) of 23 patients with amoebic colitis. No patients with non-amoebic hepatic disorders and healthy control subjects had any detectable level of amoebic antigens in CICs. Immunoblot assay revealed E. histolytica antigens of relative molecular masses of 35, 56, 70, and 90 kDa present in CICs of 64 of 76 patients with amoebiasis. The 35-kDa polypeptide was observed in 52 patients (81.25%). The results of the study suggest that the 35-kDa polypeptide antigen can be a diagnostic marker in active amoebiasis.

Injection drug use in Calcutta: a potential focus for an explosive HIV epidemic.

Our objective was to assess HIV risk perceptions, risk behaviours and factors that may facilitate an increase in injection drug use in Calcutta. Focus group discussions and in-depth interviews were conducted with a selected group of drug users to delineate drug use patterns, languages used to express addictive and related experiences and acceptance of harm minimization messages. Results from these were used to develop a semi-structured interview instrument which was used to interview 111 drug users (76 IDUs and 35 non-IDUs) recruited from jails and detoxification centres. Secondary data of narcotic seizures for the last 5 years were collected from the Calcutta police department. Data on percentage of IDUs admitted to large detox facility in the city was also collected. Findings show that HIV/AIDS knowledge and risk perceptions were low; sharing of injection equipment was reported by 66% of the injectors; and condom use was insignificant. Non-availability, rising cost and increasing tolerance to heroin were cited as factors contributing to switch to injection. Ecological association was found between intensified police activity and an increase in: the amount of smokable heroin seized; increased injection of buprenorphine; and admission to detoxification centres. In addition to HIV, IDUs were also found to be prone to hepatitis B and C. The findings suggest an urgent need for developing and implementing community-based HIV prevention interventions targeting drug users in Calcutta.

Detection of immune complexes in tissues of persons infected with Entamoeba histolytica.

Immune complexes were detected by radioimmunoassay in colonic tissue from 71 to 122 patients (58%) excreting Entamoeba histolytica cysts and in liver tissue from 5 of 16 of these patients. Complexes were also found in colonic tissue from 9 of 56 other patients (16%) who were not excreting cysts.

Zymodeme alteration of Entamoeba histolytica isolates under varying conditions.

Cysts of Entamoeba histolytica obtained from 2 asymptomatic subjects were cloned in vitro and the isoenzyme patterns and virulence of the cultures derived from them were determined. Incubation in Diamond's TYI-S-33 medium with Crithidia sp. for 80 d resulted in a change from zymodeme III to zymodeme II, with consistent virulence. Axenization by replacing Crithidia sp. with crithidial lysate had no further effect on the zymodeme but the virulence of the amoebae was attenuated. A reversal to zymodeme III, together with augmentation of virulence, was observed on the 20th day after transfer of axenic amoebae to Diamond's TYSGM-9 medium containing the original bacterial flora. The possibility that the isoenzyme pattern determining the zymodeme and the virulence behave as 2 independent variables in E. histolytica is discussed.

High cell surface hydrophobicity of virulent Entamoeba histolytica isolates.

Thirty isolates of Entamoeba histolytica were examined for their cell surface hydrophobicity. It was observed that increased hydrophobicity of the trophozoites was associated with lesion-forming ability in hamster liver, a higher rate of erythrophagocytosis and greater resistance to complement. The relationship of cell surface hydrophobicity to other virulence markers in E. histolytica is discussed.

Virulence of nonpathogenic zymodemes of Entamoeba histolytica isolates from asymptomatic subjects in Calcutta, India.

1. The zymodeme and virulence of 31 Entamoeba histolytica isolates obtained from asymptomatic human subjects in Calcutta, India are described. 2. Virulence was measured by the extent of lesion diameter (mm) induced by each isolate in the liver of golden hamsters and resistance of isolates to non-immune hamster sera in vitro. 3. Two nonpathogenic zymodemes, III (N = 17) and IV (N = 14), were detected among 31 isolates by isoenzyme electrophoresis. Most of the zymodeme III isolates were moderately to highly virulent while a quarter of the zymodeme IV were invasive although with low virulence. 4. The virulence of the isolates was found to have a significant positive correlation (r = 0.96, P < 0.001) with their greater resistance to complement-mediated lysis. 5. The data suggest that the virulence of E. histolytica is probably not related to its zymodeme.

Virulence of nonpathogenic zymodemes of Entamoeba histolytica isolates from asymptomatic subjects in Calcuta, India

The zymodene and virulence of 31 Entamoeba histolytica isolates obtained from asymptomatic human subjects in Calcuta, India are described. Virulence was measured by the extent of lesion diameter (mm) induced by each isolated in the liver of golden hamsters and resistance of isolates to non-immmune hamster sera in vitro. Two nonpathogenic zymodemes, III (N=17) and IV (N=14), were detected among 31 isolates by isoenzyme electrophoresis. Most of the zymodeme III isolates were moderately to highly virulent while a quarter of the zymodeme IV were invasive although with low virulence. The virulence of the isolates was found to have a significant positive correlation (r=0.96, P<0.001) with their greater resistance to complement-mediated lysis. The data suggest that the virulence of E. histolytica is probably not related to its zymodeme

Enhancement of virulence of Entamoeba histolytica by in vitro liver treatment.

Enhancement of the virulence of five strains of Entamoeba histolytica (three xenically maintained and two axenically maintained) was studied after in vitro incubation with normal hamster liver. Increased virulence was shown by the ability of a small number of liver-treated trophozoites to produce liver lesions in hamsters. Enhancement of virulence was positively correlated with increased resistance to normal hamster serum complement in vitro.

Study of Entamoeba histolytica isolates from Calcutta with special reference to their zymodeme, animal pathogenicity and erythrophagocytosis.

Entamoeba histolytica isolates, obtained mainly from asymptomatic human cyst passers, were tested for their in vitro erythrophagocytic activity and lesion-forming ability in hamster liver. Simultaneous zymodeme typing of the isolates showed that, along with the pathogenic zymodemes, a number of isolates having nonpathogenic zymodemes also produced liver lesions in hamsters and engulfed higher numbers of RBCs. The observed positive correlation between the rate of erythrophagocytosis of an E. histolytica trophozoite and its degree of lesion-producing capacity in hamster liver suggest that the erythrophagocytosis assay in conjunction with the hamster liver inoculation test, can be useful in the identification of virulent E. histolytica isolates.

Experimental hepatic amoebiasis in inbred mice.

A model of hepatic amoebiasis in two inbred strains of mouse (Swiss and BALB/c, has been developed by introducing Entamoeba histolytica-infected hamster liver tissue in between the adjacent liver lobes of mouse. It is expected that this model might be useful in studying various parameters of host-parasitic interactions and experimental chemotherapy of amoebiasis with relative ease.

Cronkhite-Canada syndrome with hypothyroidism.

An elderly man with non-familial gastrointestinal polyposis, malabsorption and progressive hypoproteinemia is reported. Associated alopecia, cutaneous hyperpigmentation and nail dystrophy with loss of nails were consistent with the diagnosis of Cronkhite-Canada syndrome. Hypothyroidism was present in this patient and the rare association of these two conditions is discussed.

Ultrasonographic evaluation of carcinoma of the gall bladder.

Out of 6018 patients who were evaluated ultrasonographically for gastrointestinal problems over a four-and-a-half year period, 201 patients with a mean age of 53 years were diagnosed to have carcinoma of the gall bladder (3.3%). In 191 of these the diagnosis was confirmed by laparotomy and histopathological examination and in 3 other patients ultrasound guided fine needle aspiration cytology yielded malignant cells. In the remaining 7 patients the diagnosis was not confirmed by tissue examination-3 had metastases and 4 refused further investigation. Two sets of features were detected on ultrasonography: type I-a mass occupying the gall bladder fossa and obliterating the lumen (144 patients), and type 11-a polypoid lesion projecting into the gall bladder lumen (57 patients). Gallstones were present in 157 patients (78%) but more often in patients with the type I features. Associated ultrasonographic features such as liver and lymph node involvement, dilatation of intrahepatic bile ducts and ascites were also assessed. We conclude that abdominal realtime ultrasonography is a reliable method for diagnosing carcinoma of the gall bladder.

A model of hepatic amoebiasis in random bred mice.

This study describes a model of hepatic amoebiasis in random bred mice (MF2). Mice were infected by introducing liver tissue from hamsters (Mesocricetus auratus), containing about 5 X 10(4) trophozoites of Entamoeba histolytica, between adjacent liver lobes. Direct inoculation of xenic E. histolytica resulted in mortality within 24 h, whereas monoxenic and axenic strains failed to produce any lesions. Serial mouse liver passage resulted in increased lesion score, number of metastatic abscesses, and mortality. Metronidazole 150 mg/kg produced complete healing of the abscess. It is expected that this model will be useful to study host-parasite interactions, immunology and experimental chemotherapy of amoebiasis.

Bicarbonate enhances sodium absorption from glucose and glycine rehydration solutions. An in vivo perfusion study of rat small intestine.

Sodium, potassium and water absorption was studied over the whole length of rat jejunum and ileum by an in vivo marker perfusion technique. The composition of solutions were similar to the oral rehydration solution currently in use for the treatment of acute diarrhoeal diseases. The study shows that bicarbonate and chloride containing glucose or glycine electrolyte solutions induce a significantly greater absorption of sodium, potassium and water compared to those containing chloride only. The study also confirms that an amino acid such as glycine is as efficient as glucose in promoting the absorption of sodium, potassium and water from rat small intestine.

A specific solid-phase assay for the detection of immune complexes containing Entamoeba histolytica antigens.

An assay specific for immune complexes containing Entamoeba histolytica antigens has been developed. Rabbit antibody specific for human gamma globulin is attached to a solid phase (nitrocellulose). During the first incubation step polyethylene glycol-precipitated immune complexes are bound to the rabbit antibody attached to the solid phase. In the second incubation step a radiolabelled rabbit antibody specific for Entamoeba histolytica combines with E. histolytica antigens in the complexes. Quantitation of the radiolabel provides a direct measurement of the level of specific immune complexes. The principle of the method has been verified using artificial soluble immune complexes prepared by mixing a pool of serum containing a high titre of anti-E. histolytica antibodies (greater than 1:2048 by hemagglutination assay) with the E. histolytica antigen. This antigen was prepared from axenically cultured NIH:200 strains of Entamoeba histolytica. Using sera from patients with clinical amoebic disease this method detected immune complexes containing E. histolytica in a high proportion of cases.

99mTc-2,3-diaminopropionic acid complex as renal function agent: comparison of biological properties with 99mTc-DTPA and 131I-OIH.

The preparation, purification, biodistribution, blood disappearance kinetics and imaging characteristics of 99mTc-2,3-diamino propionic acid (99m-Tc-DAPA) is studied. The latter three studies were conducted on rabbits as the experimental animal and the data thus obtained were compared with 99mTc-diethylenetriaminepentaacetic acid (99mTc-DTPA) and 131I-orthoiodohippurate (131I-OIH) with a view to find a possible replacement of the latter radiopharmaceutical with a more convenient 99mTc based compound. Preliminary data indicates favourable results for 99mTc-2,3-diamino propionic acid which warrants further investigation.

A simple ELISA for antigiardial antibody using the membrane fraction of the parasite as antigen.

Most existing methods for detecting antigiardia lamblia antibody require the use of cultured Giardia lamblia trophozoites as antigen in immunofluorescent and enzyme-linked immunosorbent assays. However, the maintenance of trophozoite culture systems limits the large-scale use of these antibody detection systems. An antigen extracted from Giardia lamblia by the detergent Triton X-100, when used in an ELISA system, produces specific, objective, quantitative and reproducible results. It is likely that such a test system could be packaged in kit form for large-scale diagnostic and epidemiological application in all parts of the world.