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H Hof

Publications and source records attributed to H Hof.

At least 163 records · Page 9Linked to original sources
PubMed1983

[Antibiotic therapy in the compromised host--presented as a model for listeriosis in the mouse. II. Effect of tetracycline].

The effectiveness of tetracycline therapy on Listeria-infection in compromised host was evaluated in three different murine models. In normal adult mice infected with a tetracycline susceptible strain of Listeria monocytogenes, treatment with this antibiotic caused a reduced rate of multiplication of bacteria. That is, a low bacterial count was found in the spleen. When the macrophage system which in Listeria-infection represents a major defense mechanism was blocked through dextran sulfate 500, treatment with tetracycline was still very effective. In this case, bacterial multiplication has ceased. However, an elimination of the organisms could only be achieved after the macrophage system recovered from its temporary blockade. Secondly, nude athymic mice which are unable to develop cell mediated immunity were used to establish chronic infection with Listeria. Treatment with tetracycline in this instance only reduced bacterial counts moderately. Thirdly, five days old baby mice which are extremely susceptible to Listeria could at least partially be protected with tetracycline therapy against fatal infection.

Animals↗
PubMed1982

Antibacterial effects of niridazole. I. Effect on infection of mice with Salmonella typhimurium.

Niridazole was shown to be an effective chemotherapeutic agent for mice infected intravenously with a niridazole-sensitive strain of Salmonella typhimurium. Death rates as well as bacterial counts per spleen were reduced, even in compromised animals. Histologic examination of spleens proved the reduction of inflammatory reaction due to Salmonella infection. A suppressive effect of niridazole treatment on immunity to challenge infection with S. typhimurium was not found, as demonstrated by infection with a niridazole-resistant strain of S. typhimurium.

Animals↗
PubMed1982

[Antibacterial effects of niridazole. II. Effects on aerobic and anaerobic bacteria].

Niridazole which is chemically related to metronidazole is endowed with much better antibacterial activity. First, several genera of aerobic bacteria, such as Salmonella and Escherichia, are susceptible to niridazole, whereas metronidazole is completely ineffective. There exist, however, some particular strains which are naturally resistant to niridazole. The in vitro activity of niridazole is still increased, if these facultative anaerobic bacteria are tested under anaerobic growth conditions. Second, niridazole has a higher in vitro activity against anaerobic bacteria, such as Bacteroides spp., Clostridium spp., Fusobacterium spp. and Peptococcus sp., than metronidazole. Extremely low MIC values of niridazole were found ranging from 0.0037 to 0.06 microgram/ml. Propionibacterium acnes, which are resistant to the action of metronidazole, are also relatively resistant to niridazole.

Aerobiosis↗
PubMed1982

[Special position of strongly haemolytic strains of the genus Listeria].

The special status of the strongly haemolytic strains of serovar (sv) 5 of Listeria monocytogenes is reviewed. Besides some biochemical reactions sv 5 strains are characterized by their excessive haemolysis on sheep blood agar and by a positive result of the CAMP test with R. equi. The haemolysis is caused by a soluble thermolabile protein which stimulates the formation of antibodies and which is inhibited by cholesterol. Sv 5-strains are less virulent than strains of sv 1/2a and sv 4b. The antibiotic sensitivity patterns characteristic for listeriae and for the principles of treating Listeria infections, are valid for sv 5-strains, too. The special position of sv 5 versus the other serovars of L. monocytogenes - with particular reference to its biochemical activity, its haemolytic properties, its lysosensitivity and its pathogenicity - calls for a reconsideration of its taxonomic position within the genus Listeria.

Antigens, Bacterial↗
PubMed1981

Biological activity of Bordetella pertussis in lipopolysaccharide-resistant mice.

Effects of Bordetella pertussis organisms, such as adjuvanticity, induction of hypersplenia, and leukocytosis as well as modification of nonspecific resistance to infection and typical morphological response of lymphatic organs, were studied in the lipopolysaccharide-resistant C3H/HeJ mouse strain. It was shown that B. pertussis exerted all of these effects in C3H/HeJ mice, although the morphological response, hypersplenia, and modification of resistance to infection with Listeria monocytogenes in such animals were less pronounced than those in lipopolysaccharide-sensitive mouse strains. This indicated that the biological activity of B. pertussis as determined in the present studies, is due partly to structural components other than lipopolysaccharide.

Adjuvants, Immunologic↗
PubMed1981

Murine model for therapy of listeriosis in the compromised host. I. Effect of ampicillin.

Therapy of listeriosis with ampicillin was examined in two murine models with compromised defense mechanisms. In mice treated with dextran sulfate paralysing the function of the macrophage system, ampicillin was less able to reduce death rates as well as bacterial counts in the spleens than after infection of normal mice. In nude mice with chronic listeriosis, treatment with ampicillin was started 8 days after infection. The numbers of viable listeria cells decreased under therapy, but a bacteriologic cure was not achieved in a 6-day schedule. Relapse followed cessation of therapy.

Ampicillin↗
PubMed1979

Anti-infective properties of vitamin A.

1. Six months after feeding a vitamin A free diet the liver content of mice was markedly reduced but not yet completely exhausted. These vitamin A deprived mice were either immunized with sheep erythrocytes or infected with Listeria monocytogenes. In comparison to normal control mice no significant difference ws observed. This indicates that neither the immune system nor the mononuclear-phagocytic system was involved. 2. Mice treated with a high dose of vitamin A showed increased antibody production against sheep erythrocytes and also increased resistance against infection with L. monocytogenes. These experimental findings indicate a stimulatory effect on the immune system and the mononuclear phagocytic system. As a conclusion it is deduced that the term "anti-infective vitamin" does not hold absolutely true for vitamin A, although certain anti-infective properties cannot be denied.

Animals↗
PubMed1979

Age-related defense against infection with intracellular pathogens.

Young adult (6--12 weeks old) and aged (20--24 months old) NMRI mice were infected with various intracellular parasites. The following results were obtained: (1) After a sublethal infection with Listeria monocytogenes, aged mice were found to show a resistance similar to that of young adults. A challenge infection with this pathogen was followed by specific immunity of long duration in both age-groups. (2) On the other hand, young animals were significantly more resistant to Salmonella typhimurium than aged mice. It was concluded that this was due to the LD50 which was 14 times greater for 2-month-old than for 20-month-old mice. Furthermore, during 7 weeks after infection there were more S. typhimurium in the spleens of senescent mice than in those of young adult controls. (3) Aged mice showed highly increased susceptibility to the weakly virulent DX strain of Toxoplasma gondii. Almost all aged animals died whereas the control mice survived. When death of the aged mice was prevented by treatment with sulfadiazine after infection with the DX strain, the aged mice were found to be as well protected against subsequent infection with the strongly virulent BK strains as the young adult mice. These results suggest that the susceptibility of the aged animal to infectious agents may considerably vary from one pathogen to another.

Aging↗
PubMed1978

Reversion of dextran sulfate-induced loss of antibacterial resistance by Bordetella pertussis.

Parenteral injection of dextran sulfate 500 (DS 500; 50 mg/kg of body weight) into mice caused a complete loss of resistance to a sublethal (2 X 10(3) to 5 X 10(3)) infection with Listeria monocytogenes. Such loss could be prevented by pretreatment of animals with 3 X 10(9) heat-killed Bordetella pertussis organisms (PO) 5 to 30 days before the administration of DS 500. The increased phagocytic capcity induced by PO was only exhausted when a fourfold dose of DS 500, effecting complete loss of antibacterial resistance (50 mg/kg ob body weight), was administered. Listeriosis in mice treated with DS 500 is characterized by rapid-progressive necro-purulent inflammation of liver and spleen, lack of mononuclear phagocyte response, and 100% lethality within 72 h after infection. In contrast, the time course, extent, and morphological characteristics of listeriosis in animals pretreated with PO before the DS 500 application were not significantly different from those of nonpretreated controls. Evidence is presented that the protective effect of PO is due to activation of the mononuclear phagocyte system, which without such treatment is blocked by the DS 500 administration. The data presented indicate that the protective effect of PO is due only in part to the endotoxic moiety of these bacteria. Differences in the course and morphology of listeriosis in animals with dysfunction of the mononuclear phagocyte system and in animals with deficiency of the cellular immune system are discussed.

Adjuvants, Immunologic↗
PubMed1978

Postnatal development of resistance against infection in an experimental model.

The postnatal development of resistance against infection was monitored by the treatment of juvenile mice with a virulent strain of Listeria monocytogenes. It could be shown that until day 10 after birth, young mice succumbed to an infection with even minimal doses of bacteria. Between day 15 and 30, the resistance against infection gradually increases until the rather constant level of grown-up animals is reached (Fig. 1). Juvenile mice that survive the primary infection are able to build up a state of immunity, which is rather similar to that of grown-up mice (Fig 3). Immunity against L. monocytogenes is mainly expressed by a functionally active T-cell system; the maturity of these cells in 15 days old mice could be demonstrated by the transfer of cells to "nude"-mice, which lack a thymus (Fig. 4). A significant increase of the non-specific resistance can be achieved even in 10 days old mice by the injection of adjuvants like pertussis organisms or endotoxin of Salmonella typhi some days before infection (Fig. 5, Fig. 6). Our findings suggest that a deficiency of functionally active macrophages is responsible for the insufficient resistance against infection with L. monocytogenes in young mice.

Animals↗