Effects of LPS on the behavioural stress response of genetically selected aggressive and nonaggressive wild house mice.

The bacterial endotoxin lipopolysaccharide (LPS) exerts strong effects on the immune-neuroendocrine network. On behaviour, LPS induces the symptoms of sickness behaviour. Otherwise, LPS challenge shares with psychological stress some common physiological adaptations. The proposal of this study was to analyse the effects of the LPS injection on the behavioural response in the shock-probe defensive burying test of two wild house mouse lines genetically selected for short (SAL) and long (LAL) latency to attack a conspecific. It is known that with previous exposure to stress, each of these lines exhibits behaviour in the burying test that is closely related to their different neuroendocrine patterns of response, with higher expression of burying in the SAL and immobility in the LAL mice. LPS (0.5 ml, 375 microg/Kg) or sterile saline (0.9%) was i.p. injected 3.5h before the beginning of the test. Non-injected mice were used as a general control of stress of handling and drug effect. The following behaviours were analyzed: defensive burying, immobility, rearing, grooming, exploration and jumping. The procedure of injection was found to be a stimulus that induced behavioural alterations in the SAL and LAL mice. Some behavioural changes induced by saline injection resembled that induced by LPS injection; in both lines an increase in immobility as well as a decrease in burying behaviour was observed. It is noteworthy that the LAL mice increased more their immobility than the SAL mice after saline or LPS injection, and the decrease in burying in the saline and LPS-injected mice was lower in the SAL than in the LAL mice. These results and others discussed in the text suggest that the active coping strategy of SAL mice and the passive coping strategy of the LAL mice, the hallmark of each line in the shock-probe burying test is present after psychological as well as LPS challenge exposure.

Pair housing affects anxiety-like behaviors induced by a social but not by a physiological stressor in male Swiss mice.

The role of pair housing in the modulation of anxiety-like behaviour in socially and physiologically stressed mice was investigated. The protocol of psychosocial stress consisted of submitting male adult mice to daily social confrontation with a male conspecific for a period of thirteen days. In an attempt to study a possible effect of pair housing as a social support, each male mouse was housed with a female throughout the period of experimentation, except during the agonistic interactions. As a physiological stressor, 10(9) sheep red blood cells (SRBC)/ml were injected intraperitoneally on the 1st and 7th days of the experiments. The respective control groups were as follows: non-socially stressed, non-pair housed and saline-injected mice. The humoral immune response was analysed by haemagglutination assay. The level of anxiety-like behaviours was measured in the elevated plus-maze test on the 13th day of the experiment. As a result, no significant changes in humoral immunity to SRBC were observed in mice subjected to social confrontation in a neutral arena as compared to non-socially stressed mice. As a consequence, no effect of pair housing on humoral immunity to SRBC could be evaluated. Concerning the effects of pair housing on the anxiety-like behaviours, it was possible to demonstrate that the pair housing proved to be effective in modulating anxiety-like behaviour, although in the stressed groups the percentage of time in the open arms and the time in risk assessment did not change in a symmetrical opposite form, as expected. The physiological stressor induced an anxiety-like behaviour that was not reversed by the pair housed condition. This suggests that different types of stressors activate different neural and peripheral pathways, which may or may not be modulated by pair housing, a finding that deserves our attention as a way to better understand the mechanisms that influence adaptations to stress.

Toxicity and antiviral activity of cinnabarin obtained from Pycnoporus sanguineus (Fr.) Murr.

This work describes the cytopathic effect on cells, cytotoxic action on mice, and antiviral activity of cinnabarin. This substance had no effect on mouse neuroblastoma cells (NA cell, ATCC clone C-1300) at a concentration of 0.31 mg/ml, it was not able to cause toxic effects in mice at concentrations of 1000 mg/kg, and reduced by four times the titers of the rabies virus at concentrations of 0.31 mg/ml.

Somaclonal variation: a morphogenetic and biochemical analysis of Mandevilla velutina cultured cells.

Cell cultures of Mandevilla velutina have proved to be an interesting production system for biomass and secondary metabolites able to inhibit the hypotensive activity of bradykinin, a nonapeptide generated in plasma during tissue trauma. The crude ethyl acetate extract of cultured cells contains about 31- to 79-fold more potent anti-bradykinin compounds (e.g., velutinol A) than that obtained with equivalent extracts of tubers. Somaclonal variation may be an explanation for the wide range of inhibitor activity found in the cell cultures. The heterogeneity concerning morphology, differentiation, carbon dissimilation, and velutinol A production in M. velutina cell cultures is reported. Cell cultures showed an asynchronous growth and cells in distinct developmental stages. Meristematic cells were found as the major type, with several morphological variations. Cell aggregates consisting only of meristematic cells, differentiated cells containing specialized cell structures such as functional chloroplasts (cytodifferentiation) and cells with embryogenetic characteristics were observed. The time course for sucrose metabolism indicated cell populations with significant differences in growth and metabolic rates, with the highest biomass-producing cell line showing a cell cycle 60% shorter and a metabolic rate 33.6% higher than the control (F2 cell population). MALDI-TOF mass spectrometric analysis of velutinol A in selected cell lines demonstrated the existence of velutinol A producing and nonproducing somaclones. These results point to a high genetic heterogeneity in general and also in terms of secondary metabolite content.

Somaclonal variation: a morphogenetic and biochemical analysis of Mandevilla velutina cultured cells

Cell cultures of Mandevilla velutina have proved to be an interesting production system for biomass and secondary metabolites able to inhibit the hypotensive activity of bradykinin, a nonapeptide generated in plasma during tissue trauma. The crude ethyl acetate extract of cultured cells contains about 31- to 79-fold more potent anti-bradykinin compounds (e.g., velutinol A) than that obtained with equivalent extracts of tubers. Somaclonal variation may be an explanation for the wide range of inhibitor activity found in the cell cultures. The heterogeneity concerning morphology, differentiation, carbon dissimilation, and velutinol A production in M. velutina cell cultures is reported. Cell cultures showed an asynchronous growth and cells in distinct developmental stages. Meristematic cells were found as the major type, with several morphological variations. Cell aggregates consisting only of meristematic cells, differentiated cells containing specialized cell structures such as functional chloroplasts (cytodifferentiation) and cells with embryogenetic characteristics were observed. The time course for sucrose metabolism indicated cell populations with significant differences in growth and metabolic rates, with the highest biomass-producing cell line showing a cell cycle 60 percent shorter and a metabolic rate 33.6 percent higher than the control (F2 cell population). MALDI-TOF mass spectrometric analysis of velutinol A in selected cell lines demonstrated the existence of velutinol A producing and nonproducing somaclones. These results point to a high genetic heterogeneity in general and also in terms of secondary metabolite content

In vivo and in vitro responses to poly(ethylene terephthalate-co-diethylene glycol terephthalate) and polyethylene oxide blends.

Although biocompatible polymeric compounds are generally nontoxic, nonimmunogenic, and chemically inert, implants made from these materials may trigger acute and chronic inflammatory responses. These inflammatory reactions may induce degeneration of implanted biopolymer. Interactions between implanted biomaterial and inflammatory cells are mediated by many cellular events involving cellular adhesion and activation. We studied the inflammatory responses in vivo and in vitro to samples of biopolymers composed of poly(ethylene terephthalate-co-diethylene glycol terephthalate) plus 0, 5, 25% of polyethylene oxide. We observed that these biopolymers did not induce inflammatory responses when implanted in the peritoneal cavity of mice for 28 days. However we observed deposition of hyaluronic acid at the surface of implanted biomaterial, suggesting that tolerance to biomaterial occurred after surgical implantation. No significant adhesion of inflammatory cells such as mononuclear phagocytes and peripheral leukocytes were observed in vitro, when poly(ethylene terephthalate-co-diethylene glycol terephthalate) blends were used as substratum to cellular adhesion. These results suggest that blends composed of poly(ethylene terephthalate-co-diethylene glycol terephthalate) induce low inflammatory cell adhesion, since no rejection of biopolymer was observed when implanted in experimental animal models.

Experimental Trypanosoma cruzi cardiomyopathy in BALB/c mice: histochemical evidence of hypoxic changes in the myocardium.

Mice inoculated three times at intervals of 15 days with epimastigote forms of an 'avirulent' strain of Trypanosoma cruzi and challenged 30 days after the last inoculation with trypomastigote forms of the 'Colombia' strain of T. cruzi develop a cardiomyopathy very similar to that observed in the chronic phase of Chagas' disease in man. The most conspicuous histopathological finding in both human and experimental chagasic cardiomyopathy is focal myocardial necrosis and degeneration. Based on the nature of cell necrosis and degeneration, and the association of this lesion with intravascular platelet aggregation in the experimental model, we suggested that the microcirculation could be involved, via transient ischaemia, in the pathogenesis of chagasic cardiomyopathy. Additional support to this hypothesis is given by the results of the present study showing histochemical evidence of hypoxic changes in the myocardium of mice chronically infected with T. cruzi.