Lytic to temperate switching of viral communities.

Microbial viruses can control host abundances via density-dependent lytic predator-prey dynamics. Less clear is how temperate viruses, which coexist and replicate with their host, influence microbial communities. Here we show that virus-like particles are relatively less abundant at high host densities. This suggests suppressed lysis where established models predict lytic dynamics are favoured. Meta-analysis of published viral and microbial densities showed that this trend was widespread in diverse ecosystems ranging from soil to freshwater to human lungs. Experimental manipulations showed viral densities more consistent with temperate than lytic life cycles at increasing microbial abundance. An analysis of 24 coral reef viromes showed a relative increase in the abundance of hallmark genes encoded by temperate viruses with increased microbial abundance. Based on these four lines of evidence, we propose the Piggyback-the-Winner model wherein temperate dynamics become increasingly important in ecosystems with high microbial densities; thus 'more microbes, fewer viruses'.

[Peripheral nerve regeneration in mice exposed to an enriched environment]. / Regeneración nerviosa periférica en ratones expuestos a un ambiente enriquecido.

INTRODUCTION: Taking into account the fact that the literature contains no studies on how an enriched environment influences peripheral nerve lesions, in this study we analysed the characteristics of the sciatic nerve in mice submitted to axonotmesis and subsequent exposure to an enriched environment. MATERIALS AND METHODS: Twenty-four male Wistar mice (198.66 +/- 11.61 g) were distributed into the following groups: control, lesion, enriched environment grouping (EEG) and simple environment grouping (SEG). Following lesion to the nerve, the animals were placed in different cages according to the groups they had been allocated to. The enriched cage had an exercise wheel, a ladder, a ramp, and mobile food and water compartments, which were randomly changed every day. After 24 days, the sciatic nerve was analysed quantitatively, morphometrically and functionally. RESULTS: The number of axons in the EEG and SEG groups was higher than that of the control group (p < 0.05). The SEG group had a higher number of axons than the lesion and EEG groups. The diameter of the axons in the experimental groups was smaller than that of the control group. The same occurred with the diameter of the nerve fibre. The thickness of the myelin sheath was inferior in the experimental groups compared to the control, and the value for the SEG group was lower than for the lesion group. The G ratio did not differ among groups. There were no differences in the values of the sciatic function index among the groups, while in the intragroup comparison there was a difference between postoperative days 7 and 14 and the preoperative values. Functioning was restored at postoperative day 21. CONCLUSIONS: The enriched environment did not have a negative effect on axonal regeneration and maturation, but neither did it favour the process. Functional recovery was not influenced by this form of intervention.

An evaluation of clinical, serologic, anatomopathologic and immunohistochemical findings for fifteen patients with mucosal leishmaniasis before and after treatment.

Treatment of mucosal leishmaniasis (ML) can be controlled by clinical examination and by serologic titers by the indirect immunofluorescence serologic reaction (IISR). We studied the correlation between the presence of antigen in tissue determined by immunohistochemistry, the IISR titers and the anatomopathologic findings in fifteen patients with ML before and after healing of the lesions as determined by otorhinolaryngologic evaluation, and evaluated these parameters to determine which of them could be useful during follow-up. Tissue antigens became negative in four patients (group A) after treatment, with a statistically significant reduction or negativity of IISR titers (p < 0.05). This did not occur in patients in whom the antigen persisted after treatment (group B), suggesting that serologic follow-up should be performed together with the search for tissue antigen, a combination which, to our knowledge, has not been used in previous studies. The negativity of tissue antigens and the behavior of IIRS titers in group A patients probably indicate a lower possibility of recurrence. Upon anatomopathologic examination the inflammatory process was found to persist after treatment even in group A, suggesting that the permanence of inflammatory activity even in clinically healed lesions is possibly correlated with the presence of the antigen or of some unknown factor.

[A case of mucocutaneous leishmaniasis treated with success with a low dose of pentavalent antimonial]. / Um caso de leishmaniose cutâneo-mucosa tratado com sucesso com baixa dose de antimonial pentavalente.

The authors report a case of a 89 years-old woman with mucocutaneous leishmaniasis and previous diabetes mellitus and high blood pressure, who had been treated with allopurinol for 10 months without healing of lesions. Afterwards, she has been treated with meglumine antimonate, "glucantime" for 4 days, with a total dose 2,380 mg of Sbv, but developed cardiac side effects and hypokalemia, hence the treatment was withdrawn. However, this patient developed total clinical regression of lesions, in spite of she has been received low dose of this drug.