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Biomedical subjects

H M Seitz

Publications and source records attributed to H M Seitz.

At least 73 records · Page 4Linked to original sources
PubMed1992

Experiments on cryopreservation of Plasmodium falciparum.

A comparative study was carried out in order to assess the effectivity of the deep-freezing conditions for P. falciparum cultures: 1. by plunging them into liquid nitrogen, 2. by use of an established freezing program for lymphocytes. After thawing in a waterbath at 37 degrees C, samples were diluted with equal volumes of 3.5% sodium chloride solution or 15% phosphate-buffered saline supplemented glucose solution. Other samples were not diluted after thawing, but the medium was replaced twice during the first day in culture. Survival was evaluated by counting the parasites in Giemsa-stained smears taken on day 3 after thawing. We obtained the best survival rate using NaCl solution, whereas replacing the medium twice resulted in the lowest level of survival. In synchronized cultures we studied survival rates of the different developmental stages of the intraerythrocytic parasites: young trophozoites (ring stages) and schizonts. The results indicate that irrespective of the freezing technique used, the survival level of young trophozoites was high (40 and 60%). The more sensitive stages (late trophozoites and schizonts) were better protected by using the freezing program designed for lymphocytes.

Animals↗
PubMed1991

Studies on the lethal effect of ultraviolet light on Trichomonas vaginalis.

Following cultivation in Asami medium, centrifugation and resuspension in saline or in water from a medicinal spring, Trichomonas vaginalis trophozoites were exposed to well-defined doses of ultraviolet (UV) light (254 nm). We used 24- and 48-h-old trichomonads at concentrations of 1 x 10(5) and 5 x 10(4) trophozoites/ml in a total volume of 20 ml for these studies. The apparatus for UV irradiation was especially constructed for batch experiments. After irradiation at doses ranging from 80 to 160 mJ/cm2, the mobility of the parasites was reduced and morphological alterations appeared: rounding of the cells, vacuolization of the cytoplasm and even cytolysis. A dose of 401.7 mJ/cm2 killed 99.8% of the 48-h-old trichomonads when irradiation occurred in saline at a cell density of 1 x 10(5) trichomonads/ml and 98.9% when irradiation was done at a cell density of 5 x 10(4) trichomonads/ml. A dose of 362.1 mJ/cm2 killed only the more sensitive 24-h-old trichomonads. In mineral water, 241 mJ/cm2 was sufficient to kill up to 99.5% of the 48-h-old trichomonads. When 48-h-old trichomonads that had been exposed to a radiation dose of 160-240 mJ/cm2 were subcultured, they lost their ability to propagate. At a dose of 80 mJ/cm2, both the trichomonads that had been harvested during the log phase and the 48-h-old organisms suspended in mineral water lost their ability to propagate on subculture. These results indicate that 24-h-old trichomonads were more sensitive than 48-h-old organisms. Furthermore, the experiments demonstrated that a higher dose of UV radiation must be applied to T. vaginalis trophozoites than to the more sensitive bacterial strain Escherichia coli ATCC 11229 so as to achieve comparable killing results.

Animals↗
PubMed1990

Alveolar echinococcosis with involvement of the ureter and testis.

Alveolar echinococcosis is a rare disease of the liver, and occasionally of the lungs and brain, that is endemic across areas of Central Europe, the Soviet Union and Alaska. We describe a case of alveolar echinococcosis with involvement of the ureter and testis overshadowing the liver manifestation. The unusual presentation and nondemonstrable exposure to the organism caused misinterpretation of the histological findings and an initial misdiagnosis of tuberculosis.

Adult↗
PubMed1989

The relation between the two forms of COPT and levels of total IgG and IgM in acute and chronic schistosomiasis mansoni.

COPT was performed on 55 acute and 48 chronic male patients with schistosomiasis mansoni as well as on 20 control normal subject. The percentage of the segmented and the bleb reactions were determined. The total levels of IgG, IgM and IgA were measured. There was no distinct evidence that COPT shows only bleb precipitations in acute cases and only segmented reactions in chronic cases. The total levels of IgG were higher in patients who showed segmented that in those who showed bleb reactions especially in the segmented but not the bleb reactions especially in chronic cases. IgM may be responsible for the bleb reactions in acute cases.

Animals↗
PubMed1988

Observations on the implications of pathology induced by experimental schistosomiasis in baboons in evaluating the development of resistance to challenge infection.

Liver samples from 10 Schistosoma mansoni-infected baboons all yielded eggs but neither their egg counts nor duration of infection (less than 226 weeks) correlated with the slightly elevated liver collagen levels or minimal histological fibrosis observed. Approximately 10% of inert 9 and 15 micron diameter microspheres injected into the mesenteric veins of 2 baboons with acute, challenge S. mansoni infection reached their lungs (mainly 9 micron microspheres). Lung egg recoveries over 1000 were significantly less common among 175 baboons exposed once to S. mansoni infections than among 56 baboons exposed more than once. Among 221 S. mansoni-and S. haematobium-infected baboons, female worm, total tissue egg and lung egg recoveries were significantly correlated with each other but not with liver or (where available) spleen weights. Liver and spleen weights were strongly correlated with total body weight. Baboons did not develop significant liver fibrosis, even after prolonged schistosome infections. However, some liver 'leakiness' developed during acute primary and challenge infections, allowing small inert particles and eggs to pass to the lungs, but this 'leakiness' was not associated with resistance to challenge. In contrast to mice, such resistance in baboons cannot, therefore, be explained simply in terms of pathological changes due to previous infections.

Animals↗
PubMed1987

A histological study of skin reactions of baboons to Schistosoma mansoni schistosomula.

A histological study was undertaken of the cellular reaction in the skin of baboons challenged with cercariae of Schistosoma mansoni. Control animals with no previous schistosome infection were compared with baboons that had infections of varying duration. In animals infected for 10 weeks no striking inflammatory reaction was seen, the histological picture being very similar to that of the control animals. After 8 months of infection the hosts developed a strong cellular response to the invading schistosomula. The predominant cells in these reactions were eosinophil leucocytes which sometimes closely adhered to degenerating schistosomula. However, some unaffected schistosomula were found close to these intense cellular reactions, suggesting that schistosomula possess varying ability to resist the host's immunological attack.

Animals↗
PubMed1987

Pathology of malaria-infected mosquitoes.

Concepts of the basic case reproduction rate of malaria, or the vectorial capacity of malaria vectors, tend to assume that the behaviour of infected and non-infected mosquitoes will be similar. However, recent years have seen a series of studies demonstrating that mosquitoes infected with malaria or other parasites show many pathological features with important effects on their behaviour and on the transmission dynamics of the parasite. Parasitology Today will be featuring a series of reports discussing these effects and attempting to unravel the expected effects on parasite transmission dynamics; this article sets the scene.

Journal Article↗
PubMed1987

Concomitant infections of Anopheles stephensi with Plasmodium berghei and Serratia marcescens: additive detrimental effects.

The mortality rate of Anopheles stephensi increased after infection with Plasmodium berghei and correlated negatively with temperature. Development of oocysts is inhibited at temperatures above 21 degrees C. We tested the hypothesis that microorganisms were involved in killing the mosquitoes. In fact we were able to demonstrate that in our A. stephensi colony great numbers of Serratia marcescens could be found in the midgut of the insects. The highest value was 2.3 x 10(7) cfu/ml. Other bacteria were rarely seen (1 out of 30 females had flavobacteria). Serratia was neither found in larvae and pupae nor in the water of the breeding dishes. Moderate numbers were detectable in glucose solutions (for feeding of adult mosquitoes) as well as in jars where pupae emerged. Isolated Serratia strains grew faster at 25 degrees C than at 21 degrees C. In glucose solutions alone growth rates were low but they rose rapidly after the addition of blood. -In experimental infections of A. stephensi with S. marcescens (1 x 10(7) bacteria/ml glucose solution) the mortality increased at 25 degrees C. At 21 degrees C the effect of Serratia was insignificant whereas in P. berghei-infected A. stephensi the damaging effects of migrating ookinetes were obvious. Additive detrimental effects were observed at 25 degrees C in mosquitoes infected with P. berghei and Serratia concomitantly.

Animals↗
PubMed1987

Correlation between release of reactive oxygen intermediates and inhibition of Toxoplasma multiplication in mouse peritoneal and alveolar macrophages and kidney cells after in vitro incubation with Obioactin, lonomycin A, muramyl dipeptide, lipopolysaccharide or Toxoplasma lysate antigen.

The inhibition of Toxoplasma multiplication inside cells does not correlate with an enhanced release of oxygen intermediates except in the case of peritoneal macrophages treated with Obioactin. The inhibition observed in alveolar macrophages treated with Obioactin, in kidney cells treated with Obioactin or lonomycin A and in peritoneal macrophages treated with lonomycin A was not accompanied by an increment of release of oxygen intermediates. Lipopolysaccharide (LPS) and muramyl dipeptide (MDP) enhanced the release of toxic oxygen intermediates in peritoneal macrophages, but did not have any toxoplasmacidal effect. Adenosine triphosphate (ATP) content increased during Obioactin, MDP or Toxoplasma lysate antigen (TLA) treatment. The actual oxygen consumption of the peritoneal macrophages treated with Obioactin increased dose dependently, but that of TLA-, lonomycin A- or MDP-treated cells did not change. These results suggest that the relationship between the intracellular killing of Toxoplasma protozoa and the release of oxygen intermediates differs according to the cells and/or the stimuli, and that the cellular mechanism of Toxoplasma killing in the peritoneal macrophages treated with Obioactin involves an energy-dependent mechanism.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1987

Long-term in vitro suspension culture of Toxoplasma and HeLa cells.

To establish a method of mass and long-term propagation of Toxoplasma in suspension cultures and to find a technique for separating the organisms from host cells, basic investigations were carried out in a microcomputer controlled system. By using an arbitrary unit "the medium index" host HeLa cells were continuously supplied to Toxoplasma organisms for about 30 days, at cycles of 4 days. HeLa cells were well infected with Toxoplasma in the suspension cultures by leaving the medium unstirred for 15 min intervals. The separation of Toxoplasma organisms from cells was improved by treating toxoplasmas and HeLa cells mixtures with 0.4% trypsin. The total number of separated organisms obtained from 29 days cultivation period was 4.9 X 10(9). The mean generation time of Toxoplasma organisms on the 0, 10, 20 and 30 day's cultivation was calculated approximately 7.4, 9.4, 9.3 and 7.8 h, respectively.

Animals↗
PubMed1986

[Pneumocystis carinii pneumonia--a review].

Pneumocystis carinii pneumonia is a clinically, roentgenologically, and serologically uncharacteristic pneumonia of the immunodeficient patient and is caused by the opportunistic parasite Pneumocystis which is most likely a protozoon. The untreated disease is lethal. The epidemiologic, clinic, and histologic features of P. carinii pneumonia are different from those of the interstitial plasmacellular pneumonia that occurred in malnourished and premature infants between 1930 and 1960 in Europe and was caused by the same organism. P. carinii is restricted to the alveoli of the lung. Material for the direct microscopic diagnosis of the parasite can be produced by bronchoalveolar lavage. The trophozoites of P. carinii are preferably stained by Giemsa stain and the cystwalls by methenamine-silver. For a reliable diagnosis both methods should be used.

Acquired Immunodeficiency Syndrome↗