Maternal postnatal high-fat diet,rather than gestational diet,affects morphology and mTOR pathway in skeletal muscle of weaning rat

The positive regulation of insulin pathway in skeletal muscle results in increased activity of the mammalian target of rapamycin (mTOR), a positive effector of mRNA translation rate and protein synthesis. Studies that assess the activity of this protein in response to chronic high-fat diet (HFD) are scarce and controversial, and to date, there are no studies evaluating the mTOR pathway in infants exposed to gestational and postgestational HFD. This study investigated the effect of maternal HFD on skeletal muscle morphology and on phosphorylation of proteins that comprise the intracellular mTOR signaling pathway in soleus muscle of offspring at weaning. For this purpose, 10 days prior to conception, 39 female Wistar rats were randomly assigned to either control diet (CTL) or HFD. Later, rats were distributed into four groups according to gestational and postpregnancy diet: CTL/CTL (n=10), CTL/HF (n=11), HF/HF (n=10) and HF/CTL (n=8). After 21 days of lactation, pups were killed, and blood samples and soleus and gastrocnemius skeletal muscle were collected for analysis. We observed an influence of maternal postgestational diet, rather than gestational diet, in promoting an obese phenotype, characterized by body fat accumulation, insulin resistance and high serum leptin, glucose, triglycerides and cholesterol levels (P<.05). We have also detected alterations on skeletal muscle morphology — with reduced myofiber density — and impairment on S6 kinase 1 and 4E binding protein-1 phosphorylation (P<.05). These results emphasize the importance of maternal diet during lactation on muscle morphology and on physiological adaptations of infant rats.     

Homo- and heterofermentative lactobacilli differently affect sugarcane-based fuel ethanol fermentation

Bacterial contamination during industrial yeast fermentation has serious economic consequences for fuel ethanol producers. In addition to deviating carbon away from ethanol formation, bacterial cells and their metabolites often have a detrimental effect on yeast fermentative performance. The bacterial contaminants are commonly lactic acid bacteria (LAB), comprising both homo- and heterofermentative strains. We have studied the effects of these two different types of bacteria upon yeast fermentative performance, particularly in connection with sugarcane-based fuel ethanol fermentation process. Homofermentative Lactobacillus plantarum was found to be more detrimental to an industrial yeast strain (Saccharomyces cerevisiae CAT-1), when compared with heterofermentative Lactobacillus fermentum, in terms of reduced yeast viability and ethanol formation, presumably due to the higher titres of lactic acid in the growth medium. These effects were only noticed when bacteria and yeast were inoculated in equal cell numbers. However, when simulating industrial fuel ethanol conditions, as conducted in Brazil where high yeast cell densities and short fermentation time prevail, the heterofermentative strain was more deleterious than the homofermentative type, causing lower ethanol yield and out competing yeast cells during cell recycle. Yeast overproduction of glycerol was noticed only in the presence of the heterofermentative bacterium. Since the heterofermentative bacterium was shown to be more deleterious to yeast cells than the homofermentative strain, we believe our findings could stimulate the search for more strain-specific antimicrobial agents to treat bacterial contaminations during industrial ethanol fermentation.     

Statin therapy lowers muscle sympathetic nerve activity and oxidative stress in patients with heart failure

Despite standard drug therapy, sympathetic nerve activity (SNA) remains high in heart failure (HF) patients making the sympathetic nervous system a primary drug target in the treatment of HF. Studies in rabbits with pacing-induced HF have demonstrated that statins reduce resting SNA, in part, due to reductions in reactive oxygen species (ROS). Whether these findings can be extended to the clinical setting of human HF remains unclear. We first performed a study in seven statin-na?ve HF patients (56 ± 2 yr; ejection fraction: 31 ± 4%) to determine if 1 mo of simvastatin (40 mg/day) reduces muscle SNA (MSNA). Next, to control for possible placebo effects and determine the effect of simvastatin on ROS, a double-blinded, placebo-controlled crossover design study was performed in six additional HF patients (51 ± 3 yr; ejection fraction: 22 ± 4%), and MSNA, ROS, and superoxide were measured. We tested the hypothesis that statin therapy decreases resting MSNA in HF patients and this would be associated with reductions in ROS. In study 1, simvastatin reduced resting MSNA (75 ± 5 baseline vs. 65 ± 5 statin bursts/100 heartbeats; P < 0.05). Likewise, in study 2, simvastatin also decreased resting MSNA (59 ± 5 placebo vs. 45 ± 6 statin bursts/100 heartbeats; P < 0.05). In addition, statin therapy significantly reduced total ROS and superoxide. As expected, cholesterol was reduced after simvastatin. Collectively, these findings indicate that short-term statin therapy concomitantly reduces resting MSNA and total ROS and superoxide in HF patients. Thus, in addition to lowering cholesterol, statins may also be beneficial in reducing sympathetic overactivity and oxidative stress in HF patients.     

Assessment of environmental stress by the micronucleus and comet assays on Limnoperna fortunei exposed to Guaíba hydrographic region samples (Brazil) under laboratory conditions

The Guaíba Basin is a source of drinking water for Porto Alegre (RS, Brazil). The water from this basin receives industrial, urban, and rural waste from many sources. The mussel species Limnoperna fortunei was chosen based on population data, distribution, and sensitivity. Previous tests with comet assay and micronuclei frequency in this freshwater mussel have shown to be successful in biomonitoring studies. The aim of this study was to evaluate the genotoxic contamination of the Guaíba Lake Hydrographic Region, through the determination of damage by the micronuclei and comet assays in L. fortunei (golden mussel). Nine sampling sites were evaluated in three different seasons: five sites in the mouths of the main rivers that flow into Guaíba lake; one site at the mouth of a stream; one major site of sewage discharge; two sites at Guaíba lake, near a sewage discharge; and the control site in a preservation area. DNA damage was detected by the single cell gel assay, as well as the frequency of micronuclei in hemocytes of mussels exposed under laboratory conditions for 7 days to water and sediment samples. Significant results were found in different seasons in almost all sampling sites (P<0.05, ANOVA Dunnet's test). Most of the positive results were found in samples affected mainly by urban effluents. It was possible to observe that there was a weak relation between mutagenic and genotoxic responses and mussels inorganic elements contents. Seasonal variation was observed at different sampling sites, but always indicating a huge contamination near urban sewage discharge. These results are consistent with previous studies, allowing us to infer that urban contamination is the biggest problem in this region. It is also possible to infer that L. fortunei is a good sentinel organism for the Guaíba Basin.     

Experimental infection and adaptation of Rodentolepis nana to the Mongolian jird Meriones unguiculatus

A mouse-derived strain of Rodentolepis ( = Hymenolepis) nana was transferred to the Mongolian jird Meriones unguiculatus. It was found that M. unguiculatus has low susceptibility to R. nana mouse isolates. Likewise, adaptation of the parasite to jird hosts, in the absence of dexamethasone treatment, was not demonstrable, at least during ten-passage trials. Nevertheless, the parasite was able to establish, grow and develop to gravid adults in M. unguiculatus treated daily with dexamethasone. Prepatent periods in dexamethasone-treated jirds in ten-passage series ranged from 10 to 17 days post-infection (DPI), the average being 12 days, and the patent periods lasted from 18 to 30 DPI, with an average of 25 days. The population pattern of faecal egg output in immunosuppressed jirds suggests that under a daily dexamethasone treatment protocol, the parasite is able to maintain egg production as long as treatment is sustained.     

Acute exercise stimulates macrophage function: possible role of NF-kappaB pathways

Moderate physical activity when performed on a regular basis presents a number of benefits to the whole organism, especially regarding immune system function, such as augmenting resistance to infections and to cancer growth. Although glutamine production by active muscle cells as well as neuroendocrine alterations mediated by the chronic adaptation to exercise may play a role, the entire mechanism by which exercise makes the immune system aware of challenges remains mostly uncovered. This is particularly true for the effects of an acute exercise session on immune function. In this work, circulating monocytes/macrophages from sedentary rats submitted to an acute (1 h) swimming session were tested for the ability of phagocytosing zymosan particles, phorbol myristate acetate (PMA)-induced hydrogen peroxide production, nitric oxide (NO) release (assessed by nitrate and nitrite production) and the expression of NO synthases (NOS-1, NOS-2 and NOS-3). The results showed that an exercise bout induced a 2.4-fold rise in macrophage phagocytic capacity (p = 0.0041), a 9.6-fold elevation in PMA-induced hydrogen peroxide release into the incubation media (1-h, p = 0.0022) and a 95.5%-augmentation in nitrite basal production (1-h incubation; p = 0.0220), which was associated with a marked expression of NOS-2 (the inducible NOS isoform; p = 0.0319), but not in other NOS gene products. Although NOS-2 expression is nuclear factor-kappaB (NF-kappaB)-dependent, no systemic oxidative stress was found, as inferred from the data of plasma TBARS and glutathione disulphide (GSSG) to glutathione (GSH) ratio in circulating blood erythrocytes which remained constant after the acute exercise. Also, no stressful situation seemed to be faced by monocytes/macrophages, since the expression of the 70-kDa heat shock protein (HSP70) remained unchanged. We conclude that NF-kappaB-dependent induction of NOS-2 and macrophage activation must be related to local factor(s) produced in the surroundings of monocytes/macrophages.     

Redescription of Besnoitia tarandi (Protozoa: Apicomplexa) from the reindeer (Rangifer tarandus)

Besnoitia tarandi tissue cysts were found in naturally-infected reindeer (Rangifer tarandus) from Finland. Infectivity of its tissue cysts, bradyzoites, and tachyzoites to animals and cell culture was studied. The bradyzoites and tissue cysts were not infectious to out-bred mice, rabbits or gerbils. When fed tissue cysts, neither cats nor dogs excreted oocysts. However, the parasite was lethal to interferon-gamma gene knock out mice irrespective of the route of inoculation. The parasite was grown successfully in African Green Monkey cells from tissues of two reindeer for the first time. Non-dividing, uninucleate tachyzoites from smears from cell cultures were 5.6 x 1.4 microm (4.5-7.4 x 1.0-1.9, n=50) in size. Longitudinally-cut bradyzoites in tissue sections measured 7.4 x 1.3 microm (6.5-7.8 x 1.0-1.6, n=30). Ultrastructurally, tachyzoites and bradyzoites were similar to those in other Besnoitia species, and in particular to parasites described from cattle (Besnoitia besnoiti) and equids (Besnoitia bennetti) in that their bradyzoites lacked enigmatic bodies. Based on comparative analysis of three portions of nuclear ribosomal DNA (the small and large subunits and the first internal transcribed spacer) B. tarandi was found to be more closely related to the other congeners described from ungulates. The parasite was formally redescribed and specimens deposited in the US National Parasite Collection.     

Aquatic heteroptera from Mariana County, Minas Gerais, Brazil

In surveys carried out in lotic and lentic environments in Mariana County, Minas Gerais state, Brazil, 35 genera and 64 species of aquatic and semi-aquatic Heteroptera were recorded, distributed in 13 families. Thirty four species were collected in lentic environments, while in lotic environments 48 species were collected, some of them common to both environments. Nepomorpha presented the greatest number of species (45), markedly for the family Naucoridae, represented by 12 species. Among the 19 Gerromorpha species collected, eight were Veliidae and six were Gerridae.     

Ecological implications on the aggregation of <Emphasis Type="Italic">Amblyomma fuscum</Emphasis> (Acari: Ixodidae) on <Emphasis Type="Italic">Thrichomys laurentius</Emphasis> (Rodentia: Echimyidae), in northeastern Brazil

We investigated the Amblyomma fuscum load on a pullulating wild rodent population and the environmental and biological factors influencing the tick load on the hosts. One hundred and three individuals of Thrichomys laurentius were caught in an Atlantic forest fragment in northeastern Brazil, as part of a longitudinal survey on ticks infesting non-volant small mammals. Ticks (n = 342) were found on 45 individuals and the overall mean intensity of infestation was 7.6 ticks per infested rodent. Ticks were highly aggregated in the host population and the negative binomial distribution model provides a statistically satisfactory fit. The aggregated distribution was influenced by sex and age of the host. The microhabitat preference by T. laurentius probably increases contact opportunities between hosts and aggregated infesting stages of the ticks and represents important clues about the habitat suitability for A. fuscum.