Dietary tryptophan deficiency and its supplementation compromises inflammatory mechanisms and disease resistance in a teleost fish

Tryptophan participates on several physiological mechanisms of the neuroendocrine-immune network and plays a critical role in macrophages and lymphocytes function. This study intended to evaluate the modulatory effects of dietary tryptophan on the European seabass (Dicentrarchus labrax) immune status, inflammatory response and disease resistance to Photobacterium damselae piscicida. A tryptophan deficient diet (NTRP); a control diet (CTRL); and two other diets supplemented with tryptophan at 0.13% (TRP13) and 0.17% (TRP17) of feed weight were formulated. Fish were sampled at 2 and 4 weeks of feeding and the remaining were i.p. injected with Phdp (3 × 10⁶ cfu/fish) at 4 weeks and the inflammatory response (at 4, 24, 48 and 72 hours post-infection) as well as survival were evaluated. Results suggest that fish immune status was not altered in a tryptophan deficient scenario whereas in response to an inflammatory insult, plasma cortisol levels increased and the immune cell response was compromised, which translated in a lower disease resistance. When dietary tryptophan was offered 30% above its requirement level, plasma cortisol increased and, in response to bacterial infection, a decrease in lymphocytes, monocytes/macrophages and several immune-related genes was observed, also compromising at some degree fish disease resistance.

Physiopathological responses of sole (Solea senegalensis) subjected to bacterial infection and handling stress after probiotic treatment with autochthonous bacteria

This study aimed to evaluate the protective effects of four autochthonous bacteria isolated from juvenile sole (Solea senegalensis) intestine as dietary probiotic supplement against bacterial pathogen infection and handling/transport stressors. Growth performance and immune responses were evaluated after 85 days of feeding trial. Sole (IBW = 16.07 ± 0.11 g) were fed six experimental diets, a control diet (CTRL, without the dietary probiotic supplementation), and five diets supplemented with probiotic bacteria: PB1 (Shewanella hafniensis), PB2 (Enterococcus raffinosus), PB3 (Shewanella hafniensis + Arthrobacter soli), PB4 (Pseudomonas protegens + Arthrobacter soli) and PB5 (Shewanella hafniensis + Arthrobacter soli + Enterococcus raffinosus). All bacteria were selected based on their in vitro antimicrobial activity. After the growth trial, fish were submitted to a stress factor (transport) and then each dietary group was divided in two additional groups: non-infected (placebo) and infected with Photobacterium damselae subsp. piscicida. Immune and antioxidant responses were evaluated at day 10 post-infection. In infection trial A, fish were infected on the same day of transport, whereas in trial B fish were infected after a 7-day recovery from the transport stress. At the end of the feeding trial, fish fed with PB2 and PB4 showed lower final body weight when compared with the other dietary groups. Respiratory burst activity and nitric oxide production were not affected by probiotic supplementation. Fish fed with PB5 presented lower peroxidase activity compared to CTRL. Lysozyme and alternative complement pathway activity (ACH50) showed no significant differences between treatments. The innate immune responses were significantly affected after handling stress and bacterial infection. In trial A, the ACH50 levels of infected fish were significantly lower than the placebo groups. On the other hand, in trial B fish infected with Pdp demonstrated higher ACH50 levels when compared to placebos. Peroxidase levels were strongly modulated by bacterial infection and handling stress. In trials A and B, infection had a clear downgrade effect in peroxidase levels. Lipid peroxidation, catalase, glutathione S-transferase and glutathione reductase were altered by both bacterial infection and transport. Overall, dietary probiotic supplementation did not influence growth performance of sole. The immune and oxidative defenses of sole responded differently to infection depending on the probiotic and the synergy between pathogen infection and transport.

An actigraphy heterogeneous mixture model for sleep assessment

Wrist actigraphy is a well established procedure to monitor human activity. Among other areas, it has a special relevance in sleep studies where its lightweight and non-intrusive nature make it a valuable tool to access the circadian cycle. While there are several methods to extract information from the data, the differentiation between sleep and wakefulness states is still an open discussion. In this paper, the characteristics of the movements in the different states are assumed to be intrinsically different. These differences are not simply related with magnitude and movement counting, but due to real differences on the statistical distributions describing the actigraphy data. Thus it is possible to refine the discrimination level when detecting these states. The proposed methodology to characterize the actigraphy data is based on a mixture of three canonical distributions; i)Exponential, ii)Rayleigh and iii)Gaussian. It is shown that the weights and parameters estimated in each state are organized into almost separable clusters on the feature space. This suggests the ability of the method to discriminate these states based only on the movements recorded on actigraphy data.

Toxicity of beta-amyloid in HEK293 cells expressing NR1/NR2A or NR1/NR2B N-methyl-D-aspartate receptor subunits

Neurotoxicity induced by beta-amyloid peptide (Abeta) involves glutamate toxicity, resulting from overactivation of N-methyl-D-aspartate (NMDA) receptors and elevation of intracellular calcium. However, the heterogeneity of the NMDA receptors, frequently composed of NR1 and NR2A-D subunits, has been less studied. Thus, we determined the contribution of NMDA receptor subtypes on Abeta(1-40) toxicity in HEK293 cells transiently expressing NR1/NR2A or NR1/NR2B subunits. Analysis of lactate dehydrogenase (LDH) release and trypan blue exclusion revealed an increase in Abeta(1-40) toxicity upon NR1/NR2A expression, compared to NR1/NR2B, indicating loss of plasma membrane integrity. Furthermore, Abeta(1-40) decreased intracellular ATP in cells expressing NR1/NR2A. MK-801 ((+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate), a noncompetitive NMDA receptor antagonist, partially prevented the decrease in cell viability and the energy impairment. These differences were not accounted for by the activation of caspases 2, 3, 8 and 9 or calpains or by DNA fragmentation, excluding the hypothesis of apoptosis. Functional NR1/NR2A and NR1/NR2B receptor subtypes were further evidenced by single-cell calcium imaging. Stimulation of NR1/NR2A receptors with NMDA/glycine revealed an increase in intracellular calcium in cells pre-exposed to Abeta(1-40). Opposite effects were observed upon activation of NR1/NR2B receptors. These results suggest that NR1/NR2A-composed NMDA receptors mediate necrotic cell death in HEK293 cells exposed to Abeta(1-40) through changes in calcium homeostasis.

[Obesity and quality of life]

Obesity is considered one of the most relevant health problems of modern societies, as it constitutes a predominant risk factor in the development of various other diseases. The negative impact of obesity on the quality of life of individuals has been the subject of diverse research. The results of a test carried out at Gothenburg University in Sweden suggest that severe obesity is a debilitating factor both for health and psychosocial functioning. Research carried out in Madrid permitted identification of a profile of obese patients with impaired quality of life, which has enabled prophylactic intervention or early treatment of these cases to be considered. The results of a study carried out in the USA propose that pain would appear to be directly related with quality of life and could be considered a covariant of obesity, and should therefore be taken into account in obesity treatments. A study carried out in Oxford concluded that obese subjects or subjects with another chronic disease presented a deterioration in physical wellbeing, however only subjects with another chronic disease (without associated obesity) presented a deterioration in psychological wellbeing. The majority of studies suggest the negative influence of obesity and overweight on health and psychosocial functioning, however it is not possible to clearly define a linear relation between obesity and diminished quality of life.

The relationship between body mass index and educational level in young Portuguese males: 1995 and 1999 cohorts

INTRODUCTION

Over the last decades, a progressive increase in height and weight has been observed throughout Europe. Increase in weight has been more marked however, with a resulting increase in overweight and obesity prevalence. RESULTS published have analyzed the relationship between body mass index (BMI) and educational level. Most studies indicate an inverse relationship between BMI and educational level in developed countries.

OBJECTIVE

This study's main objective was to evaluate the relationship between BMI and educational level (years of schooling) in young Portuguese males in 1995 and 1999.

METHODS

Transverse study of data (BMI and years of schooling) from the military inspection records of virtually the entire Portuguese male population with an average age of 20 years, examined in 1995 and 1999, totaling 81 363 and 71 254, respectively. Four classes of BMI (<20, 20-24.9, 25-29.9 and > or =30 kg/m2) and four schooling levels (<5, 5-9, 10-12, and >12 years) were considered. We applied the chi2 test for associations between BMI and educational level and the odds ratio to quantify categorical variables. The significance level was 5%.

RESULTS

In 1995, 15.2% were overweight (BMI> or =25 years), increasing to 20.8% in 1999. The percentage of obesity (BMI> or =30 years) was 1.4% in 1995 and 2.2% in 1999. The percentage of overweight and obesity increased directly in line with the increase in educational level, both in 1995 and 1999. In 1995, the percentage of subjects with obesity according to years of schooling was as follows: <5 years--1.4%; 5-9 years--1.4%; 10-12 years--1.5% and >12 years--1.7%. In 1999, the results were as follows: <5 years--1.4%; 5-9 years--2.2%; 10-12 years--2.8% and >12 years--3.2%.

CONCLUSIONS

We can conclude that the prevalence of overweight and obesity in young male Portuguese increased in the last decade and that, unlike most developed countries, the higher the level of education, the greater the percentage of overweight and obesity, both in 1995 and 1999.

Risk factors for typhlitis

A case-control study was undertaken to identify risk factors for typhlitis in patients with hematological malignancies. A data base file with a total of 410 episodes of fever and neutropenia in patients cared for between May 1987 and 1996 was reviewed. Typhlitis was defined as a symptom complex of fever, intense abdominal pain and tenderness in the presence of neutropenia. Five cases of typhlitis were identified. Three controls for every patient were randomly selected from the same cohort. Diarrhea and jaundice were more frequent in patients than in controls (p=0.03). The presence of mucositis, prolonged duration of profound neutropenia and idarubicin treatment proved to be risk factors for typhlitis.