OCCURRENCE OF Blastocystis spp. IN UBERABA,MINAS GERAIS,BRAZIL

Intestinal parasites are a problem for public health all over the world. Theinfection with Blastocystis, a protozoan of controversialpathogenicity, is one of the most common among them all. In this study, theoccurrence of intestinal parasites, with emphasis on Blastocystis,in patients at the Universidade Federal do Triângulo Mineiro was investigated inUberaba (MG) through microscopy of direct smears and fecal concentrates usingRitchie’s method. Feces of 1,323 patients were examined from April 2011 to May 2012.In 28.7% of them at least one intestinal parasite was identified, and the mostfrequent organisms were Blastocystis spp. (17.8%) and Giardiaintestinalis (7.4%). The occurrence of parasitism was higher in children aged 6 -10years old, and the infection with Blastocystis spp. was higher abovethe age of six (p < 0.001). The exclusive presence of G.intestinalis and of Blastocystis spp. was observed in5.4% and 12.2% of the patients, respectively. Regarding patients with diarrheicfeces, 8% revealed unique parasitism of Blastocystis spp. Otherintestinal parasites observed in children were Ascarislumbricoides(0.3%) and Entamoebahistolytica/dispar/moshkovskii (1.4%). The Ritchie’s method was moresensitive (92.8%) when compared to direct microscopy (89.8%), with high agreementbetween them (97.7%, kappa = 0.92). In conclusion, the occurrence ofBlastocystis spp. in Uberaba is high and the presence ofdiarrheic feces with exclusive presence of the parasite ofBlastocystis spp. was observed.     

Gut microbiome in hemodialysis patients treated with calcium acetate or treated with sucroferric oxyhydroxide: a pilot study

Purpose

It has been proved that the gut microbiome is altered in patients with chronic kidney disease. This contributes to chronic inflammation and increases cardiovascular risk and mortality, especially in those undergoing hemodialysis. Phosphate binders may potentially induce changes in their microbiome. This trial aimed to compare the changes in the gut microbiome of hemodialysis patients treated with calcium acetate to those treated with sucroferric oxyhydroxide.

Methods

Twelve hemodialysis patients were distributed to receive calcium acetate or sucroferric oxyhydroxide for 5 months. Blood samples (for biochemical analysis) and stool samples (for microbiome analysis) were collected at baseline, 4, 12, and 20 weeks after treatment initiation. Fecal DNA was extracted and a 16S rRNA sequencing library was constructed targeting the V3 and V4 hypervariable regions.

Results

Regarding clinical variables and laboratory parameters, no statistically significant differences were observed between calcium acetate or sucroferric oxyhydroxide groups. When analyzing stool samples, we found that all patients were different (p?=?0.001) among themselves and these differences were kept along the 20 weeks of treatment. The clustering analysis in microbial profiles grouped the samples of the same patient independently of the treatment followed and the stage of the treatment.

Conclusion

These results suggest that a 5-month treatment with either calcium acetate or sucroferric oxyhydroxide did not modify baseline diversity or baseline bacterial composition in hemodialysis patients, also about the high-variability profiles of the gut microbiome found among these patients.

     

Lymphocyte homeostasis

B- and T-lymphocyte populations have an independent homeostatic regulation of resting (B and T) and activated (B) or memory (T) cell compartments. This organization may provide an efficient mechanism to ensure simultaneously a first natural barrier of protection against common pathogens, the maintenance of immunological T-cell memory and a reservoir of repertoire diversity capable of dealing with new antigenic challenges.     

CD8 lethargy in the absence of CD4 help

CD4 T cell help was proposed to have a pivotal role in orienting CD8 T cell responses to antigen stimulation. By activating antigen-presenting cells (APC), CD4 cells would induce their expression of costimulatory molecules, the "signal two" required to induce full CD8 activation, preventing CD8 tolerance. Recent data on this subject is contradictory, as the absence of help did not always result in CD8 tolerance. These differences were attributed either to the presence of residual CD4 help or, respectively to the type of antigen stimulation, the peptide affinity, the CTL frequencies, and/or the strength of the response. We therefore reassessed the role of CD4 help in CD8 responses using a system where CD4 cells are absent and APC not activated. This system can be manipulated to induce CD8 tolerance (at high antigen concentrations) or CD8 memory (at low antigen concentrations). We found that the presence of CD4 help did not prevent tolerance induction. On the other hand, the absence of CD4 help did not induce CD8 tolerance, but rather led to differentiation stage intermediate between naive/memory/tolerant cells that we call "lethargy". These findings indicate that role of CD4 help in CD8 responses does not follow a simple on-off rule, as previously suggested. They also reveal that the "tolerance versus memory" dichotomy fails to account for all possible states/properties of antigen-experienced CD8 cells. Depending on the priming conditions, other intermediate stages of differentiation may occur.     

Role of TCR-restricting MHC density and thymic environment on selection and survival of cells expressing low-affinity T cell receptors

H-Y-specific T cell receptor (TCR) transgenic mice express an MHC class I H-2D(b)-restricted TCR specific for a male antigen-derived peptide (H-Y). Selection and survival of cells expressing this low-affinity TCR were analyzed under optimal and sub-optimal conditions. Optimal conditions were provided by a thymic environment with high H-2D(b) density. Sub-optimal conditions were provided by a thymic environment with decreased H-2D(b) density or by an athymic environment with either high or low H-2D(b) density. Whereas negative selection was still guaranteed under sub-optimal conditions, selection and survival efficiency of cells expressing the transgenic TCR were strongly dependent on optimal conditions. These results indicated that both a thymic microenvironment and a high density of TCR-restricting MHC molecules were needed to ensure selection and maintenance of cells expressing TCR with low affinity and hence a more diverse T cell repertoire.     

Generation of mature T cell populations in the thymus: CD4 or CD8 down-regulation occurs at different stages of thymocyte differentiation

We have studied the differentiation and repertoire selection during the maturation of CD4⁺CD8⁺ (DP) thymocytes into CD4⁺CD8^- (CD4SP) and CD8⁺CD4^- (CD8SP) T cells, in normal mice, mice transgenic for T cell receptor (TcR)-αβ restricted by either class I or class II major histocompatibility (MHC), and in mice deficient in class I or class II MHC expression. Our data suggest that mature CD4 and CD8 T cells derive from different pathways of T cell differentiation in the thymus. Thus, interaction of DP thymocytes with MHC class II leads to the immediate down-regulation of CD8, which occurs simultaneously with an increase in TcR expression; DPTcR^loHSA^hi thymocytes mature into a CD4⁺CD8^lo TcR^hiHSA^hi intermediate population. This cell population generates CD4SP thymocytes, the majority of which are still HSA^hi. In contrast, interaction with MHC class I induces the up-regulation of TcR, which precedes the down-regulation of CD4; DPTcR^lo generate DPTcR^hi thymocytes, the majority of which are the committed precursors of CD8SP cells. Further differentiation results in CD4 down-regulation and the transition from DPTcR^hi into CD8⁺CD4^lo TcR^hiHSA^lo and CD8SPTcR^hiHSA^- T cells. Since down-regulation of CD4 and CD8 occurs at different stages of thymocyte differentiation, our results do not support a stochastic/selective model of lineage commitment in the thymus.     

Spatial patterns of tuberculosis and its association with living conditions in the city of Ribeirão Preto in the state of São Paulo

This study, with a hybrid, ecological and time-tendency design, sought to establish the relation between the spatial correlation in the occurrence of new cases of TB in the year 2000 and to ascertain the association between living conditions and TB distribution in Ribeir?o Preto, State of S?o Paulo, between 2000 and 2006. The thematic maps were elaborated with the help of MapInfo 7.5 and spatial statistical analysis using Spring 4.3. For the remaining calculations, SPSS 10.0 was used. The indices with the highest factor loads were family heads earning 2 minimum wages or less and with less than 3 years of education. The comparison of the living conditions and TB maps revealed a relation between TB and poorer areas in the city, as the incidence rate in the cluster with poor living conditions was 49.9/100,000 inhabitants. The gross Chance Ratio, considering the cluster with the high living conditions as a reference, proved the association between TB and living conditions and 3.30 for the low living conditions cluster (CR=3.30; CI95%: 1.90-5.70). The city's stratification according to living conditions and incidence of TB allowed for the identification of risk areas, providing input for the local TB Control Program.     

Jejunal dopamine and Na,K-ATPase activity in early chronic renal insufficiency

AIM: The uninephrectomised and three-quarter nephrectomised (3/4nx) rats present dopamine-sensitive enhanced natriuresis. This is accompanied in uninephrectomised rats by a reduced jejunal Na(+),K(+)-ATPase activity with recovered sensitivity to inhibition by dopamine. The present study examined the jejunal Na(+),K(+)-ATPase activity and the role of dopamine in 3/4nx animals. METHODS: Fourteen days after surgery, the L-amino acid decarboxylase activity (AADC) activity, the enzyme responsible for the synthesis of dopamine, and the Na(+),K(+)-ATPase activity, were determined in jejunal epithelial cells from 3/4nx and Sham rats. In addition, the effect of dopamine (1 micromol/L) on jejunal Na(+),K(+)-ATPase activity was evaluated in both groups. RESULTS: The 3/4nx rats presented a reduced AADC activity in jejunal epithelial cells (V(max) in nmol/mg prot/15 min, 142 +/- 6 vs 190 +/- 10, P < 0.05). In addition, the jejunal Na(+),K(+)-ATPase activity was increased in 3/4nx rats (Pi release in nmol/mg prot/min, 137 +/- 1 vs 122 +/- 2, P < 0.05). However, dopamine was unable to inhibit the Na(+),K(+)-ATPase activity in jejunal epithelial cells from both 3/4nx and Sham animals. CONCLUSIONS: In contrast to uninephrectomy, the jejunal Na(+),K(+)-ATPase activity is increased in 3/4nx rats and is not sensitive to inhibition by dopamine.     

Survival of patients treated with hemodialysis and estimated expenses in the municipality of Ribeirao Preto - SP

Using Life Table Method the present study estimated the survival of patients gone under hemodialysis, according to age group, from 1997 to 2000, in the Ribeir?o Preto County. Based in probability of survival it was also estimated the expenses referred to the sessions of hemodialysis for patients that are beginning treatment. Nearly 60% of patients followed were alive after four years of study, show high survival. The results of this study show that the high expenditure with hemodialysis refers to the increase of survival of patients and not specifically the increase of demand of the therapy.