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Biomedical subjects

G Huldt

Publications and source records attributed to G Huldt.

At least 37 records · Page 2Linked to original sources
PubMed1983

Giardia lamblia infections in a cohort of Bangladeshi mothers and infants followed for one year.

Giardia lamblia infection in an endemic area was investigated by following a cohort of 33 lactating mothers and their infants in a semiurban community of Bangladesh for one year. Eighty-two percent of mothers and 42% of infants excreted Giardia at least once during the study period. Infants became infected as early as 3 months of age, and 86% of the infected infants had diarrhea, suggesting that the first exposure to the parasite results in disease. Only one of the infected mothers had diarrhea, indicating that with repeated exposure to Giardia, mothers in an endemic area may develop partial immunity that protects against disease but not infection. An interrelationship between maternal and infant colonization was not found. Local and systemic immune responses to Giardia correlated poorly with infection, but milk antibodies were a better reflection of infection than serum antibodies were. Infection with G. lamblia was significantly lower in infants younger than 6 months (9%), an age when many are totally breast-fed. However, we were unable to establish clear-cut protection related to human milk antibodies, and suggest that the lower infection rate in younger infants results mainly from decreased exposure to Giardia cysts.

Adolescent↗
PubMed1983

Antibody-independent binding and activation of complement by Schistosoma mansoni adult worms.

The in vitro binding serum complement (C) components to Schistosoma mansoni worms was studied. By exposing frozen sections of adult male and female parasites to normal human serum, binding of both classical and alternative pathway C components was observed. By immunofluorescence (IFL) microscopy selective binding of Clq, C4 and C3 to the schistosomal tegument, internal structures, the intestinal tract and eggs was seen. The C4 and C3 binding was completely abolished in the presence of 10 mM EDTA. EGTA also completely inhibited binding of C4 and most of the C3 binding. These results suggest that C binding to S. mansoni adult worms occurs mostly by the classical activation pathway. However, the partial Ca2+ independence of C3 binding and the demonstrated binding of the regulatory protein beta 1H suggests that worms are capable also of C3 binding by the alternative pathway. No C binding occurred to intact worms. Although some in vivo bound immunoglobulin appeared to be present occasionally at the parasite surface and in the gut, this material did not account for the demonstrated extensive C deposition upon incubation of frozen sections with normal human serum in vitro. Antibody independence of the observed classical pathway C binding was further indicated by binding of isolated Clq to the same structures capable of binding C components from serum.

Animals↗
PubMed1983

Antibodies against Entamoeba histolytica in human milk and serum in Kenya.

A modified enzyme-linked immunosorbent assay (ELISA) technique has been developed for the detection of secretory immunoglobulin A (SIgA) antibodies against Entamoeba histolytica. By substituting phosphate-buffered saline-Triton for phosphate-buffered saline-Tween as the antibody incubating buffer, unspecific absorption of SIgA was avoided. As revealed by chessboard titrations, the optimal amount of antigen for coating was higher in SIgA than in IgG ELISA. A purified antigen from the membrane pellet fraction of E. histolytica gave equally good reactivity with SIgA and IgG antibodies and was used throughout. A total of 283 milk and 232 serum samples from three areas in Kenya were tested. The samples were collected in maternity hospitals on one of days 1 to 3 after parturition. All milk samples were tested for total SIgA. In one of the study areas (Machakos), the mean level of SIgA was significantly lower than in the other two areas (Mombasa and Nairobi). Eighty-seven of the milk samples (31%) were reactive in the test. The rate of positives was higher in Mombasa, where the SIgA levels were highest. Since both the frequency and the level of serum antibodies were similar in the three study areas, it is likely that the higher milk reactivity in Mombasa was mainly due to the higher SIgA concentrations observed. Antibodies were detected in 32 (14%) of the sera, mostly in low or moderate titers. Surprisingly few mothers had detectable antibodies in both milk and serum. In fact, the majority of positives were reactive in either milk or serum, with a predominance of milk positives. The background for this is probably complex, containing components such as differences in immunoglobulin concentrations in the samples, diversities in local and systemic antigenic stimulation responses, and level of immunological memory.

Amebiasis↗
PubMed1982

Distribution of exposed and hidden carbohydrates of Schistosoma mansoni adult worms demonstrated by selective binding of fluorochrome-conjugated lectins.

The distribution of exposed and hidden lectin-binding glycoconjugates in adult Schistosoma mansoni worms was studied. Fluorochrome-conjugated lectins were allowed to react both with intact worms and with frozen sections of worms. The results show a selective reactivity of lectins with tegumental surface structures, the intestine, eggs and basement membranes. Strong binding of wheat germ agglutinin (WGA) was seen to the exposed surface of intact worms. Peanut agglutinin (PNA), Ricinus communis agglutinin (RCA) and concanavalin A (Con A) gave a weaker reaction. There was a preferential affinity of PNA and RCA to the spikes covering the tubercles of male worms whereas Con A gave a more uniform staining pattern. Internal structures exposed in frozen sections of worms gave distinct staining reactions. Binding sites for Con A were widely distributed throughout the worm. PNA produced a more selective binding and was the only lectin staining basement membranes as distinct structures. There was a strong selective staining of the gut with soybean agglutinin (SBA) and RCA. Eggs seen in large quantitites inside female parasites reacted strongly with SBA and PNA and less intensely with RCA and WGA. The observed selectivity of lectin binding may reflect physiological function. The results may be important as a basis for using lectin affinity-chromatography for purification and characterization of worm constituents.

Animals↗
PubMed1980

Changes in intestinal fluid transport and immune responses to enterotoxins due to concomitant parasitic infection.

The effect of a parasitic infection on enterotoxic diarrhea and on local and systemic formation of antibody to the toxin after immunization was studied in mice. Trichinella spiralis infection was chosen as the model, since the effects of the parasite when residing in both intestinal and extraintestinal sites can be studied. It was found that during the intestinal stage of the infection, the fluid response to cholera toxin as well as dibutyryl-cyclic adenosine 3',5' -monophosphate was greatly enhanced and that this was associated with a marked reduction in the absorption of fluid from the intestine. Later in the infection (migration stage), fluid accumulation in response to cholera toxin was significantly reduced, whereas absorption was normal and secretion in response to dibutyryl-cyclic adenosine 3',5'-monophosphate was somewhat increased. Still later in the infection (muscular stage), the fluid-secretory response to cholera toxin was normal. There was a drastic depression of local formation of antitoxin of both immunoglobulin and immunoglobulin classes in mice given the first two of four oral immunizations with cholera toxin during the intestinal stage of T. spiralis infection. When the priming was given before or after the intestinal stage, the local antitoxin response was not affected. The titers of circulating antibodies were also depressed in mice given the first immunizations during the intestinal stage. In addition, significant though less pronounced depression of the serum antibody response was observed in mice primed during the extraintestinal stage.

Animals↗
PubMed1980

Effect of experimental trichinosis on intestinal secretion and on local antibody formation to cholera toxin.

The life cycle of Trichinella spiralis, a parasitic nematode, has three main stages: intestinal, migration and muscular stage. The present study was initiated to clarify the possible effects of the various stages of the infection on (a) enterotoxin induced intestinal secretion and (b) development of local immunity to cholera toxin. During the intestinal stage of trichinosis in mice challenge of ligated loops with cholera toxin gave rise to significantly greater fluid accumulation than was demonstrated in uninfected animals. In contrast, during migration and early muscular stage the secretory response was markedly reduced whereas in late muscular stage the fluid accumulation was normal. Absorption studies revealed that the intestinal fluid uptake was normal during the migration and muscular stages while it was markedly decreased during the intestinal stage which could probably explain the increased fluid accumulation in response to enterotoxin at this time. The normal absorption during the other stages suggests a true inhibition of the secretory process. To study the antibody response to cholera toxin during the various stages of T. spiralis infection the mice were given repeated peroral immunizations according to a schedule known to induce immunity to experimental cholera in mice. We found that T. spiralis infected mice, in which the immunization started ("priming") during the intestinal stage, had a significantly reduced IgA response in the small intestine. On the other hand T. spiralis infection had much less, if any effect on the IgA response to cholera toxin when immunization started before the infection and only the booster dose was given in the intestinal stage or when both priming and boosting were done after the intestinal stage.

Animals↗
PubMed1980

Evaluation of the enzyme-linked immunosorbent assay (ELISA) and other serological tests for the diagnosis of toxoplasmosis.

The enzyme-linked immunosorbent assay (ELISA) was evaluated in human toxoplasmosis in three laboratories using their own procedures. The same batch of serum samples was investigated in the three laboratories. ELISA results were compared by statistical analysis both with one another and with those of the dye test (DT), immunofluorescence (IF), complement fixation test (CFT), and indirect haemagglutination (IHA).Highly significant correlations were obtained between the three laboratories with ELISA using two different antigens and enzyme conjugates. The correlations between ELISA and the other serological tests showed the following sequence: CFT>IF>IHA>DT. Highly significant correlations were obtained between ELISA using anti-gamma-chain and anti-total immunoglobulin conjugates. The agreement in discrimination between sera with low and high antibody levels was good for all the different ELISA techniques but discrimination between positive and negative sera depended rather on the ELISA procedure used.

Enzyme-Linked Immunosorbent Assay↗
PubMed1979

On the epidemiology of human toxoplasmosis in Scandinavia especially in children.

A random sample representing approx. one-third of pre-school children and approx. 95% of school children in age groups 8, 11, 13, and 15 years in a suburb of Stockholm were examined for antibodies to Toxoplasma. Antibodies were uncommon in small children. They gradually appeared throughout childhood but especially in adolescence and adult life. Antibodies were more common in females than in males. Even small girls were more often infected than boys of corresponding age. The difference becomes marked in puberty and is significant in adults. A family study revealed evidence of familial aggregation of the infection albeit with borderline significance. No correlation was found between occurrence of antibodies and the presence of cats in the families or reported consumption of raw meat. The majority of representative samples of Lapps and Skolt Lapps in northern Scandinavia lacked antibodies to Toxoplasma.

Adolescent↗
PubMed1977

Effect of experimental trichinosis on unrelated humoral and cell mediated immunity.

Immune responses to unrelated antigens were studied during the course of Trichinella spiralis infection in mice. A transitory depression of the IgM response to the thymus dependent antigen, sheep erythrocytes, was seen three weeks after infection and this effect was more pronounced after challenge. A depression of the IgG response also was observed, however, not until 6 weeks after infection. The humoral response to the thymus independent antigen, polyvinyl pyrrolidone showed a slight increase which was most evident in challenged mice. The nonspecific cellular immune response, as measured by the split heart allograft technique, showed a profound and longlasting depression. This effect was mot pronounced one week after inoculation, when the parasite resides mainly in the intestine. The time at which the nonspecific cellular immunity was most depressed coincides with the period of strong specific cell mediated immunity. It is also shown that experimental trichinosis in CBA mice is accompanied by profound but transient changes in the thymus reflected mainly as a depletion of cortical thymocytes. These changes were not due to corticosteroids or malnutrition. There is reason to believe that thymic depletion is of significance for the depressed antibody response, but not for the prolonged survival of allografts. These findings indicate that T. spiralis affects the nonspecific immunity at different levels.

Adrenalectomy↗
PubMed1977

On porcine toxoplasmosis in Sweden.

An outbreak of fatal toxoplasmosis in piglets, probably of congenital origin is described. Although this is the first known manifest case of porcine toxoplasmosis in Sweden it is concluded that it is based on a well established latent infection of the pig population in the area concerned. Of a random sample of clinically healthy slaughtered pigs from the area 40.3 per cent were positive in Sabin-Feldman dye-test.

Acute Disease↗
PubMed1976

Tumorigenicity of Epstein-Barr virus (EBV)-transformed lymphoid line cells in autologous squirrel monkeys.

Eight squirrel monkeys (Saimiri sciureus) challenged with EBV or EBV-transformed SLCL were naturally or experimentally infected with Plasmodium knowlesi or Pl. brasilianum. Most of the animals had been splenectomized and unilaterally nephrectomized. Three of these monkeys received one dose of 6 to 12 X 10(8) autologous SLCL. These lines were derived from saimiri lymphoid cells permanently transformed by B-EBV in vitro. All three animals developed multiple undifferentiated malignant lymphomas and died 8 to 10 days post inoculation. Necropsy tumor specimens were EBNA-positive and contained 7 to 21 EBV genome equivalents per cell. EBNA- and EA-positive SLCL were established in vitro from four tumor explants of two monkeys. These results demonstrate that in vitro EBV-transformed SLCL are able to cause tumor formation in autologous squirrel monkeys. Five monkeys received high transforming doses of B-EBV or S-EBV, derived from one of the tumorigenic SLCL. None of the animals developed any sign of tumor formation during an observation period of up to 130 days. Three of these monkeys showed no detectable EBV-related seroconversion while the sera of two monkeys had become anti-EBNA-positive when tested at days 28 and 130 respectively post inoculation. Two additional monkeys received neither EBV nor SLCL. They showed no clinical evidence of tumor development or spontaneous seroconversion over a period of more than 1 year.

Animals↗
PubMed1975

New serological test for malaria antibodies.

In an enzyme-linked immunosorbent assay test for malaria antibodies, antibodies to Plasmodium vivax and P. falciparum in man are detected using a crude antigen prepared from the simian malaria parasite P. knowlesi. The test may be suitable for epidemiological studies.

Adsorption↗