[Chronic pollution with environmental toxins: formaldehyde]. / Chronische Belastung mit Umwelttoxinen: Formaldehyd.

Formaline is a colourless, strongly odoriferous gas. It is a very important basic component in chemical industry. It has become well known as a poison in residential areas due to its appearance in chipboard panels. Formaline causes a variety of acute and chronic toxic stress symptoms. In many cases the relation of formaline exposition and symptoms is difficult to demonstrate. The main keys to diagnosis are a very careful anamnesis and the cumulated appearance of symptoms. We intend to show several possible sources of stress symptoms caused by formaline, as well as diagnostic possibilities. This includes several methods of diagnostic assessing formaline concentration in the air, and several suggestions for the reduction of formaline emission.

Morphological response of mycoplasma to fleroxacin.

Quinolones exhibit partially reduced activity in vitro against genital mycoplasma. Therefore, the morphological response to fleroxacin, a difluorinated quinolone, by Mycoplasma hominis was studied. Even at subinhibitory concentrations the ultrastructural investigations revealed distinct alterations such as cytolysis, vacuole and cell "ghost" formation. The typical dumbbell-shaped cells observed with monofluorinated compounds were not found, which may indicate a qualitatively different mode of action.

Ciprofloxacin in combination with metronidazole.

Ciprofloxacin has a reduced activity against anaerobic pathogens. Therefore, a combination of ciprofloxacin with an antimicrobial agent active against anaerobes, such as metronidazole, seems to be interesting for the treatment of mixed aerobic/anaerobic infections. High metronidazole concentrations (10 mg/l or 40 mg/l) neither affected the bactericidal efficacy of ciprofloxacin on aerobic pathogens, such as Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Enterococcus faecalis, nor on the anaerobic pathogens Clostridium perfringens and Clostridium difficile, as demonstrated by kill-kinetic curves. The same high concentrations, as well as lower therapeutically achievable concentration (2 mg/l or 5 mg/l) of metronidazole in combination with ciprofloxacin were slightly more potent for the tested clostridia than ciprofloxacin or metronidazole alone.

How does Toxoplasma gondii enter host cells?

Toxoplasma gondii, an obligate intracellular protozoal parasite, is the etiologic agent of toxoplasmosis. A main event in the pathologic course of this organism is the infection of both phagocytic cells and "nonprofessional phagocytes"--e.g., heart cells--and the subsequent destruction of these cells following massive multiplication of the parasite therein. There are two mechanisms of invasion. The parasite may enter a cell such as a macrophage by the well-known mechanism of phagocytosis without triggering its own death inside the cell. By the other process, communication of the parasite's apical pole and the host cell membrane may evoke a sequence of invasion steps different from that of phagocytosis. This invasion process involves the cooperation of the host cell and the parasite. The entry of the parasite is characteristically a rapid process that requires the input of energy by both of the cells involved. A series of cytochalasin-sensitive morphologic changes that are undergone by the parasite and the host cell lead to the interiorization of the parasite. Chemical factors, as well as membrane composition, microviscosity, and membrane structures on the host cell membrane, modulate the parasite's entry.

Polycationic polypeptides: a possible model for the penetration-enhancing factor in the invasion of host cells by Toxoplasma gondii.

The effect of polycationic polypeptides (polylysine, polyarginine and polyhistidine) on the invasion of mammalian cells and plant protoplasts by Toxoplasma gondii was studied. In JM cells, a human lymphoblastoid cell line with T cell characteristics, all polycationic polypeptides used increased the invasion rate in a concentration-dependent manner. This effect and the morphological changes revealed by electron microscopy resembled the action of the penetration-enhancing factor previously described by E. Lycke and co-workers. Plant protoplasts of Catharanthus roseus, which are resistant to T. gondii invasion, showed the same morphological changes in the presence of polycationic polypeptides as observed for JM cells, but were not invaded.

[The antimycotica disc elution test: a new quantitative antimycotica test for yeasts (author's transl)]. / Der Antimykotikaplättchenelutionstest: eine neue quantitative Möglichkeit der Antimykotikatestung von Sprosspilzen.

The number of opportunistic yeast infections has increased during the last years. Therefore, testing of antimycotica has become important in terms of reliability and speed. Todays testing is essentially based on the disc diffusion susceptibility test and to a minor extent on the evaluation of the minimal inhibitory concentration. Two disc diffusion tests were compared. Both tests were shown to be practicable as a screening test. However, false positive results were obtained at a rather high percentage. Therefore, a new antimycotica test based on the disc elution test was developed and compared to a disc diffusion test. The resistance patterns for 5-fluorocytosine assayed by the disc elution test were in good agreement to the minimal inhibitory concentration. The test was shown to be adaptable for the imidazole-antimycoticas as well.

Attempts to infect plant protoplasts with Toxoplasma gondii.

The interaction of tachyzoites of Toxoplasma gondii with plant protoplasts was compared with their interaction with cultures of HeLa cells. Unlike the HeLa cells, the plant protoplasts were refractory to invasion under all conditions tested. The lack of invasion was not an artefact of the protoplast isolation technique. This is the first description of a cell type refractory to Toxoplasma invasion; hence possible mechanisms for the specificity of parasite-host cell interaction can now be studied.

Toxoplasma gondii: membrane properties of active energy-dependent invasion of host cells.

The energy-dependence and the significance of membrane stability for the active invasion of host cells by Toxoplasma gondii has been examined in vitro. The penetration of Toxoplasma as measured by the infection rate can be significantly decreased by blocking the parasitic respiratory chain with CN-. The infection rate of blocked parasites is nearly normalized when glucose is present during the infection period. This suggests a strong energy-dependence for the active infection mechanism. DMSO (dimethylsulfoxide) known to increase membrane stability is able to lower the infection rate if either the target or the effector cell is pretreated. Ca2+ was shown to exhibit a similar effect. Procain, which destabilizes the cell membrane, stimulates the invasion of host cells by Toxoplasma parasites. The possible modes of action on the invasion schedule for the different effectors are discussed.

[Toxoplasmosis transmission by blood transfusion? (author's transl)]. / Toxoplasmose durch Blutübertragung? Morphologische Studien zur Frage des Befalls von Blutzellen durch Toxoplasma gondii.

T-cells of the chicken tumour HPRS-1, mouse mastocytoma cells, Friend virus-transformed erythroleukaemia cells as well as normal human, mouse and chick erythrocytes were tested for their receptivity to toxoplasma infection. The studies indicate that T-cells and mastocytoma cells, which may be counted as part of the white blood cell series, have the highest invasion rate after incubation with toxoplasma. Friend-erythroleukaemia cells were less often affected; mature human, mouse and chick erythrocytes were refractory. The results suggest that cells of the white blood cell series are receptive to toxoplasma infection but that nucleated precursors of the red series may also be so, while mature erythrocytes cannot be infected. The possibility of transmission of toxoplasmosis by blood transfusion can no longer be doubted.