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Biomedical subjects

N Weiss

Publications and source records attributed to N Weiss.

At least 163 records · Page 9Linked to original sources
PubMed1980

[Incidence of hepatitis virus infections and diseases in travelers returning from the tropics].

Travellers' hepatitis has been investigated by comparing clinical and serological data. The histories of 876 persons examined after their return from tropical countries were analysed for type, location, and length of stay abroad, prophylactic administration of gamma-globulin and past hepatitis. In addition to clinical investigations, 528 of the patients underwent radioimmunoassays for hepatitis markers. HBs antigen was detected in 1.1%, anti-HBs antibodies in 14.2%, and anti-HA antibodies in 37.3% of the patients. The prevalence of anti-HA antibodies increased with age, but the mean value for those over 20 years was only 8% above the mean for the corresponding age groups of Swiss residents. Significant differences in prevalence of anti-HA antibodies were only observed in persons who had stayed in the tropics for more than 5 years. The prevalence of hepatitis B markers was 2-3 times higher in persons returning from the tropics than in volunteer Swiss blood donors. Contrary to hepatitis A, the hepatitis B markers were related neither to age nor to the length of stay abroad. Patient's histories and serological tests revealed a high frequency of unapparent infections, i.e. 74% of hepatitis A and 88% of hepatitis B infections. Acute viral hepatitis was newly diagnosed in 17 out of the 2032 tropical patients who consulted us during 1979. The yearly incidence of hepatitis in this population was thus 8.5%, which is about 10 times higher than that estimated for the Swiss population as a whole. Only 5 of the 17 cases showed hepatitis of type A. One third of the cases were anicteric. The study clearly shows the importance of non-A hepatitis among travellers. In consequence, questions arise as to the prophylactic use of gamma-globulin and the epidemiology of traveller's hepatitis.

Acute Disease↗
PubMed1980

Studies on Dipetalonema viteae (Filarioidea). 5. Ultrastructural aspects of the antibody-dependent cell-mediated destruction of microfilariae.

The antibody-dependent cell-mediated destruction of Dipetalonema viteae microfilariae was followed by electron microscopy both in vitro and within micropore chambers in vivo. There was a correlation between the degree of adherence (1% mf with adhered cells) and the degree of microfilarial damage. Polymorphonuclear leukocytes, predominantly neutrophils, seemed to be responsible for the destruction of microfilariae in vivo. An in vitro assay indicated that eosinophils also have a role as potent effectors against microfilariae. The first sign of microfilarial damage is the disintegration of cuticular layers. In a later stage of destruction, lysis of the hypodermis or even of the whole microfilarial tissues was observed.

Animals↗
PubMed1979

Comparative evaluation of 7 helminth antigens in the enzyme-linked immunosorbent assay (E.L.I.S.A.).

112 sera from Europeans with parasitologically proven helminthiasis were tested in the enzyme-linked immunosorbent assay (E.L.I.S.A.) against 6 crude extracts of various helminths (2 of adult worms: Dipetalonema viteae, Fasciola hepatica; 3 of eggs: Ascaris suum, Toxocara canis, Schistosoma mansoni; and of Echinococcus granulosus scolices) and against bovine hydatid fluid. Each serum was tested simultaneously at a fixed dilution of 1:160 against all antigens. Extensive cross-reactions were observed, leading to the conclusion that non-purified helminth antigens, even in combination, are of limited value for reliable serodiagnosis in E.L.I.S.A.

Animals↗
PubMed1979

Development of Dipetalonema viteae third-stage larvae (Nematoda: Filarioidea) in micropore chambers implanted into jirds, hamsters, normal and immunized mice.

Development of third-stage larvae of Dipetalonema viteae within subcutaneously implanted micropore chambers proceeded in all hosts tested up to the fourth-stage larvae and occasionally to adolescent worms. In the jird the timing of development was comparable to a natural infection. Although the mouse is an insusceptible host, larval development could take place, but was very slow. Two intraperitoneal inoculations of living third-stage larvae into mice induced the production of antibodies against the larval cuticle and against common antigens. In such immune mice the development of third- and fourth-stage larvae within micropore chambers was significantly inhibited, larval mortality was increased, and the larval motility was impaired.

Animals↗
PubMed1979

Studies on Dipetalonema viteae (Filarioidea) 3. Antibody-dependent cell-mediated destruction of microfilariae in vivo.

Antibody-dependent cell-mediated destruction of Dipetalonema viteae microfilariae could be demonstrated in the golden hamster using a micropore chamber technique. Microfilariae were eliminated within 24 hours in chambers of 3.0 and 5.0 microm pore size when implanted into amicrofilaremic hamsters (week 30 post infection). At peak microfilaremia (week 12 post infection), only some hamsters could efficiently destroy microfilariae. In chambers with 0.3 microm pore size, microfilariae survived for more than 3 weeks in all hamsters. In uninfected hamsters, microfilariae could only be eliminated if they had been preincubated with serum or its 19S fraction containing antibodies to the cuticle of microfilariae. The opsonizing activity of the serum was abolished by 2-mercaptoethanol treatment. The composition of cells adhering to microfilariae was always significantly different from the composition of cells which migrated into a chamber. The adhesion patterns on individual microfilariae indicated that no single effector cell type was responsible for the destruction of microfilariae. The eosinophil was the predominant cell type but neutrophils, lymphocytes and monocytes also adhered to the microfilariae. Cellular adhesion led to the immobilization of microfilariae and subsequently to their disintegration within large cell clusters. During the final stages of destruction the contribution of the monocyte became more pronounced.

Animals↗
PubMed1979

Studies on Dipetalonema viteae (Filarioidea). 4. Passive transfer of immunity to circulating microfilariae by spleen cells.

Passive transfer experiments provided clear evidence for a role of spleen cells in the immunity of hamsters against Dipetalonema viteae microfilariae. 106 or more spleen cells from postpatent (amicrofilaraemic) hamsters suppressed incipient microfilaraemia in syngeneic recipients when transferred at either week 2 or week 6 of a primary infection. Spleen cells from microfilaraemic donors (week 15-16 post infection) were also capable of transferring immunity against microfilariae. The spleen cell transfer never affected the survival of adult worms. After transfer of spleen cells from either patent or postpatent hamsters, antibodies to the cuticle of microfilariae could be found in the sera of recipients as early as week 8 of a primary infection.

Animals↗
PubMed1978

Radioallergosorbent and indirect fluorescent antibody tests in immunodiagnosis of schistosomiasis.

Radioallergosorbent tests for specific IgE antibodies to Schistosoma haematobium and S. mansoni were positive in 82 and 72%, respectively, of sera from 136 African schistosomiasis patients. 99% of sera from controls (5 free of parasitic disease, 75 infested with hookworm, Ascaris, Trichuris, and/or Onchocerca) were negative. When titres in indirect fluorescent antibody tests were set at the same level of specificity only 38% of patients' sera were positive. A cut-off at a higher concentration increased sensitivity to 65% but lowered specificity (10% controls positive).

Adolescent↗
PubMed1978

[Malaria introduced into Switzerland from 1974-1976].

In recent years there has been an increase in imported tropical diseases in Switzerland. Travellers to the tropics are often inadequately or not at all informed about the dangers and possible prophylaxis of infection. This is true for malaria, of which 207 cases covering the years 1974 to 1976 are studied. Most involved were people between 21 and 30 years old. The main infections (71%) come from African countries. Plasmodium falciparum was found somewhat more frequently than P. vivax. Only a seventh of those infected took chemoprophylaxis regularly. Very many took irregular prophylaxis, while scarcely a third ever took an antimalarial drug. All the severe cases were in this group. A review is conducted of aspects of malaria in Switzerland, a country where the disease is not endemic. However, as it can be brought in at any time from tropical areas, it must be considered in the diagnosis of various clinical pictures. As the characteristic course of the fever is rare and onset of the disease often follows later than a month after the return from the infection area, malaria is only recognized late. The diagnosis is nevertheless relatively easy if the possibility of malaria is borne in mind.

Adult↗
PubMed1978

Studies on Dipetalonema viteae (Filarioidea) I. Microfilaraemia in hamsters in relation to worm burden and humoral immune response.

The course of a primary infection with Dipetalonema viteae was studied in one randomly bred and in one inbred strain of hamster. Worm recovery and the duration and intensity of the microfilaraemia were analyzed and related to the humoral immune response of the host by using the indirect immunofluorescent antibody test on frozen sections of female worms, on eggs and on intact microfilariae. The inbred strain showed a greater susceptibility to the parasite. This was evidenced by high worm recovery and prolonged microfilaraemia. The duration of microfilaraemia did not depend on the number of recovered female worms. Most of the randomly bred hamsters suppressed microfilaraemia by week 30 post infection whereas some hamsters of the inbred strain were still microfilaraemic. Splenectomy prior to infection did not affect the duration of microfilaraemia. Antibodies to the cuticle of microfilariae always appeared in the sera after immunity to circulating microfilariae had been built up.

Animals↗
PubMed1978

Studies on Dipetalonema vitae (Filarioidea). II. Antibody dependent adhesion of peritoneal exudate cells to microfilariae in vitro.

Peritoneal exudate cells from normal uninfected hamsters adhered in vitro to microfilariae in the presence of 19S antibody fractions from hamsters which had suppressed or were going to suppress their microfilaremia. The adhering cells were predominantly mononuclear, although eosinophils were occasionally found. Experiments with sensitized microfilariae and peritoneal exudate cells indicated that the macrophage probably recognizes the microfilariae/antibody complex. Macrophage cytophilic antibodies did not seem to be involved. This adhesion reaction may initiate the trapping of microfilariae in vivo, thus contributing to the observed acquired immunity to circulating microfilariae in the hamster.

Animals↗
PubMed1977

Schistosomiasis mansoni in the hamster: cellular and humoral immune responses to soluble egg antigens (SEA).

Cellular and humoral immune responses to soluble egg antigens (SEA) were studied in the course of Schistosoma mansoni infection in the hamster. No immune response to SEA could be detected before the parasite had started oviposition. The liver granuloma size reached a maximum 6 weeks after infection and decreased rapidly thereafter. The in vitro cell-mediated immune response to SEA (lymphocyte blast transformation) showed a maximum reaction 12 to 16 weeks after infection (depending on the infection rate) and also declined later. Parallel to the lowered reactivity of the lymphocytes to SEA in vitro, responsiveness to the nonspecific T-cell mitogen, phytohemagglutinin M, was also reduced in chronic infections. Humoral anti-SEA antibodies could be detected in increasing amounts up to 10 weeks after exposure.

Animals↗