CD95-induced apoptosis in health and disease dimers at the DISC and the effect of c-FLIP R on L. Monocytogenes infection

Magdeburg, Univ., Fak. für Naturwiss., Diss., 2013

Mathematical models of influenza A virus infection : from intracellular replication to virus growth in cell populations

Magdeburg, Univ., Fak. für Verfahrens- und Systemtechnik, Diss., 2015

Neuronal alterations in chronic cerebral Toxoplasma gondii infection

Magdeburg, Univ., Fak. für Naturwiss., Diss., 2015

Infection by microorganisms on soybean seeds obtained from plants treated with growth regulators

This research, deals with the effects of exogenous growth regulators on infection by microorganisms on soybean (Glycine max cv. Davis) seeds. To study the influence of the chemicals, soybean plants were sprayed with gibberellic acid (GA) 100 ppm, (2-chloroethyl) trimethylammonium chloride (CCC) 2,000 ppm, succinic acid-2,2-dimethy1hydrazide (SADH) 4,000 ppm, indolylacetic acid (IAA) 100 ppm, 2,3,5-triiodobenzoic acid (TIBA) 20 ppm (three applications), and Agrostemin (1g/10 ml/ 3 1). Application of growth regulators did not affect infect ion by microorganisms on soybean seeds. The prominent fungus isolated was Phomopsis sojae. Alternaria and Fusarium spp. were isolated from seeds. The presence of a bacterium on the seeds was observed. The delay in harvest and high humidity increased the number of seeds from which Phomopsis was recovered.

Pneumocystis carinii: its incidence in rodents and enhancement of the infection by corticosteroids

A survey was made on the incidence of Pneumocystis carinii in 361 rodents including sewer rats, albino rats, albino mice, guinea-pigs and rabbits. P. carinii was found in 4 of the 215 Rattus norvegicus examined (1,8%). These results accord with recent observations but disagree with investigations made by the researchers who first studied this parasite in the past when high indexes of infection were found. However, in 20 albino rats treated with corticosteroids (betamethazone) we found 8 positive (40%) and in 20 albino mice treated by the same way, 9 were positive for P. carinii (45%). These results confirm the opportunistic character of P. carinii in rodents already well demonstrated in man.

Cross-infection experiments with "isospora" of cats and dogs

Feces of 34 dogs out of 251 (13.5%) from guanabara were positive for Isospora. From these 19 (7.5%) were i. rivolta, 13 (5.2%) were I. canis and 2 (0,7) were i. bigemina. "Free-sporocysts" of I. rivolta were eliminated by 9 dogs (3.5%). A "Caryospora-like" oocyst was seen once. Cross-infection experiments performed with Isospora from dogs and cats failed to produce infection while inoculations of these Isospora in their natural hosts succeeded. The results suggest that the species of Isospora occurring in cats are different from those of dogs.

Development of cell mediated immunity to flagellar antigens and acquired resistance to infection by Trypanosoma cruzi in mice

Modulation by BCG and/or cyclophosphamide of sensitization of mice with flagellar fraction (a tubulin-enriched fraction) prevented death of mice challenged with T. cruzi CL strain trypomastigotes recovered from Vero cells. A methodology was ceveloped to assay specific antigens and to determine optimal doses for sensitization and elicitation of DTH in mice. CL strain is predominantly myotropic strain which does not produce important parasitism of mononuclear phagocyte cells; these cells appear to control infection when activated in vivo. Maximum protection was seen in this study when BCG and cyclophosphamide were associated, but protection was observed also when cyclophosphamide, that prevents supressor T cells, was applied 2 days before flagellar fraction sensitization in normal mice. These experiments suggested that the macrophage may have an important role in the early phases of infection particularly when nonspecific stimulation is associated with specific sensitization. A correlation betwen delayed hypersensitivity to parasite antigens and protection was observed.

A water-borne hepatitis A outbreak in Rio de Janeiro

An excess of hepatitis cases, in the research center of Petrobrás located in the Fundaão Island, within the city of Rio de Janeiro, was notified during the second half of March 1980. In recent years this center has had an average of four cases per year, but between March 5th and April 25th, sixteen cases were reported. The cause and possible source of infection were investigated. A serologic diagnosis of hepatitis A was made by showing IgG serum antibodies against this virus in patients. No subclinical cases among a group of 60 healthy employees could be identified. A questionnaire was circulated to investigate a possible commom source of infection. Evaluation of the water supply system indicated that it had recently been contaminated. Information obtained from other medical services in the island failed to reveal that the episode was part of a larger outbreak.

Unsusceptibility of Biomphalaria occidentalis to infection with a strain of Schistosoma mansoni

Susceptibility experiments with 1582 specimens of Biomphalaria occidentalis, 3-6 mm in shell diameter, from 10 localities of the states of Mato Groso, Mato Grosso do Sul, Paraná and São Paulo, exposed individually to 5 miracidia of Schistosoma mansoni (SJ2 strain), gave negative results. B. tenagophila from Joinville (Santa Catarina) and Taubaté (São Paulo), used as controls, showed infection rates of 17.9% and 14.8%, respectively. Experiments with other strains of S. mansoni are in progress. If the present results are confirmed, expansion of schistosomiasis toward far-western Brazil through the agency of B. occidentalis becomes less probable.

Immunopathology of Schistosoma mansoni infection in rabbits: (A preliminary report)

Five rabbits infected with Schistosoma mansoni showed marked resistance, which resulted in low worm recovery and low egg production. Pathological changes appeared in liver and intestines as scattered foci of eosinophilic infiltration around immature eggs, with only occasional granulomatous formation. Antibodies to ovular and adult worm structures were demonstrated by immunofluorescence in the sera of rabbits prior to infection (natural antibodies) and specially following infection by S. mansoni. These findings point out to the peculiarities of the immunopathology of schistosomiasis in rabbits.

Host factors influencing outcome of Leishmania mexicana infection in mice

Studies were undertaken to determine the influence of several host-related parameters on the course of Leishmania mexicana mexicana infection in inbred C57B1/10 (C57) and outbred albino (OA) mice. An important influence of the following variables was demonstrated: Host strain: lesions in C57s were significantly less variable in size and outcome than those of OAs under the conditions studied and even when persistent developed at a slower rate. Host age: Subcutanous injection of 2 x 10 [raised to the power of 4] to 2 x 10 [raised to the power of 6] amastigotes into the dorsum of the rear paw produced significantly larger lesions which healed more slowly in 2 mo. old C57s than in 4 mo. old mice. Reduced healing ability was observed in older (8 mo. old) female C57s, and low mortality occurred after 15 months of age in infected mice of both sexes. Lesion site: Following amastigote infection, lesions in paws of most C57s regress within 15 - 25 wks. In contrast, perinasal legions produced with the same number of parasites tend to persist for the life of the animal as slowly spreading irregular nodules. In animals infected in both locations, each lesion site behaves similarly to that in singly infected animals of the same age, i.e. regression in the two sites is independent. Our results indicate that while host strain may strongly influence infection outcoem, such variables as lesion site and host age play important roles and may explain, in part, reported inter- and intraexperimental variability in responses of murine hosts to a given leishmanial parasite.

Characterization of human heterophil hemolysins induced by Schistosoma mansoni infection

Heterophil antibodies could be detected in sera from normal or from patient with chronic schistosomiasis. Their hemolytic activities depend on the integrity of the complement classic pathway. The heterophil antibodies from patient sera presented a higher specificity for Schistosoma mansoni antigen preparations than those detected in normal sera. Most of the hemolytic activity observed in normal sera can be destroyed at 56ºC for 4 min. On the other hand, about 80% of the sera from infected patients are partially or totally resistant to this heat-treatment. The hemolytic activities of sera were eluted from a gel filtration column in different fractions of the first peak.

Comparasion of polyacrylamide gel electrophoresis (PAGE), immuno-electron microscopy (IEM) and enzyme immunoassay (EIA) for the rapid diagnosis of rotavirus infection in children

Detection of rotavirus RNA by polyacrylamide gel electrophoresis (PAGE) proved to be a highly sensitive and rapid diagnostic test. A comparison of this assay with immuno-electron microscopy (IEM) and enzyme immunoassay (EIA) in 245 faeces from children with gastroenteritis revealed complete agreement between the three assays in 238 (97.14%) samples. Among 75 samples positive in at least one of the three assays, negative results were observed in 5 (6.48%) by PAGE, in 6 (6.76%) by EIA and in none by IEM. Silver staining greatly increased the sensitivity of the PAGE assay. We conclude that although IEM remains the most sensitive and rapid rotavirus diagnostic assay, the PAGE technique has many advantages in its favour, including the non-requirement of expensive equipment, the use of only chemically defined reagents and the capacity to distinguish virus subgroup and variants and to detect non-crossreactive rotaviruses which are missed in serological assays.

Some characteristics of hyperreactivity to bacterial lipopolysaccharide induced in mice by Trypanosoma cruzi infection

Mice infected with T. cruzi strain, acquire a high level of susceptibility to the effects of bacterial gram-negative LPS. The LD50 of adult female SW mice to LPS from S. typhosa, decreases from 450 to 2,5 mcg 10-12 days after T. cruzi infection. This hyperreactivity to LPS induced by T. cruzi presents all the characteristics of that found in infection caused by many other agents. During the acaute phase of experimental infection with T. cruzi Y strain, mice generally die with a hypovolemic shock very similar to that induced in uninfected animals injected with an adequate dose of bacterial endotoxin. There is evidence for and against the hypothesis that LPS absorbed from the instestinal tract may be involved in the mechanism of death of mice during the acute phase of T. cruzi infection.