Effect of ketogenic diet on nucleotide hydrolysis and hepatic enzymes in blood serum of rats in a lithium-pilocarpine-induced status epilepticus

The ketogenic diet (KD) is a high-fat and low-carbohydrate diet, used for treating refractory epilepsy in children. We have previously shown alterations in nucleotidase activities from the central nervous system and blood serum of rats submitted to different models of epilepsy. In this study we investigated the effect of KD on nucleotidase activities in the blood serum, as well if KD has any influence in the activity of liver enzymes such as alkaline phosphatase, aspartate aminotransferase, and alanine aminotransferase activities in Wistar rats submitted to the lithium–pilocarpine model of epilepsy. At 21 days of age, rats received an injection of lithium chloride and, 18–19 h later, they received an injection of pilocarpine hydrochloride for status epilepticus induction. The results reported herein show that seizures induced by lithium–pilocarpine elicit a significant increase in ATP hydrolysis and alkaline phosphatase activity, as well as a decrease in ADP hydrolysis and aspartate aminotransferase activity. The KD is a rigorous regimen that can be associated with hepatic damage, as shown herein by the elevated activities of liver enzymes and 5′-nucleotidase in blood serum. Further studies are necessary to investigate the mechanism of inhibition of lithium on nucleotidases in blood serum.     

The life cycle of Ascocotyle (Phagicola) longa (Digenea: Heterophyidae), a causative agent of fish-borne trematodosis

The complete life cycle of the trematode Ascocotyle (Phagicola) longa (Digenea: Heterophyidae) is elucidated by natural observation validated by experimental infections. The natural first intermediate host of A. (P.) longa, an agent of human heterophyiasis in Brazil, is the cochliopid snail Heleobia australis (new first intermediate host). Metacercariae were found encysted in the body musculature, heart, stomach, liver, kidney, spleen, gonads and mesentery of mullets Mugil liza. Hamsters Mesocricetus auratus were experimentally infected with metacercariae of A. (P.) longa obtained from the mullets, and the adults recovered were used to infect the snails H. australis. Rediae and cercariae of A. (P.) longa are described for the first time. The ultrastructure of the tegument of A. (P.) longa shows a change in spination pattern from the cercaria with single-pointed spines to the metacercaria and adult with multipointed, brush-shaped spines. The life cycle of A. (P.) longa is related to estuaries and coastal lagoons where the recruitment of mugilid juveniles occurs. The high prevalence (100%) of A. (P.) longa encysted in the mullets examined within the urban area of Rio de Janeiro indicates the potentially great public health impact of the consumption of raw mullets.     

Electrically and Thermally Conducting Nanocomposites for Electronic Applications

Nanocomposites made up of polymer matrices and carbon nanotubes are a class of advanced materials with great application potential in electronics packaging. Nanocomposites with carbon nanotubes as fillers have been designed with the aim of exploiting the high thermal, electrical and mechanical properties characteristic of carbon nanotubes. Heat dissipation in electronic devices requires interface materials with high thermal conductivity. Here, current developments and challenges in the application of nanotubes as fillers in polymer matrices are explored. The blending together of nanotubes and polymers result in what are known as nanocomposites. Among the most pressing current issues related to nanocomposite fabrication are (i) dispersion of carbon nanotubes in the polymer host, (ii) carbon nanotube-polymer interaction and the nature of the interface, and (iii) alignment of carbon nanotubes in a polymer matrix. These issues are believed to be directly related to the electrical and thermal performance of nanocomposites. The recent progress in the fabrication of nanocomposites with carbon nanotubes as fillers and their potential application in electronics packaging as thermal interface materials is also reported.     

X-linked insertion/deletion polymorphisms: forensic applications of a 33-markers panel

Insertion/deletion (INDEL) polymorphisms are diallelic markers with potential characteristics for use in forensics and biological anthropology, including: the simplicity of laboratory analysis, the possibility of genotyping many markers in a single PCR multiplex reaction, as well as analyzing markers with special inheritance types, such as those linked to the X chromosome (X-INDEL). In this work we developed a laboratory analysis methodology using a 33-INDEL marker panel for the X chromosome in a single PCR multiplex reaction, followed by a capillary electrophoresis run. We employed the panel to genotype a sample of 351 individuals of a mixed population from the Brazilian Amazon. The results demonstrate that the measurement of biostatistical parameters for forensic use in this population is compatible with prior estimates from other populations using current X-STR panels.     

Spastic Paraplegia, Optic Atrophy, and Neuropathy: New Observations, Locus Refinement, and Exclusion of Candidate Genes

SPOAN is an autosomal recessive neurodegenerative disorder which was recently characterized by our group in a large inbred Brazilian family with 25 affected individuals. This condition is clinically defined by: 1. congenital optic atrophy; 2. progressive spastic paraplegia with onset in infancy; and 3. progressive motor and sensory axonal neuropathy. Overall, we are now aware of 68 SPOAN patients (45 females and 23 males, with age ranging from 5 to 72 years), 44 of which are presented here for the first time. They were all born in the same geographic micro region. Those 68 patients belong to 43 sibships, 40 of which exhibit parental consanguinity. Sixty-one patients were fully clinically evaluated and 64 were included in the genetic investigation. All molecularly studied patients are homozygotes for D11S1889 at 11q13. This enabled us to reduce the critical region for the SPOAN gene from 4.8 to 2.3 Mb, with a maximum two point lod score of 33.2 (with marker D11S987) and of 27.0 (with marker D11S1889). Three genes located in this newly defined critical region were sequenced, but no pathogenic mutation was detected. The gene responsible for SPOAN remains elusive.     

Association of Diarrheagenic Escherichia coli Pathotypes with Infection and Diarrhea among Mexican Children and Association of Atypical Enteropathogenic E. coli with Acute Diarrhea

Seventy-six children ≤2 years old were prospectively followed for 1 year in a peri-urban community of Mexico City to determine asymptomatic infection and acute diarrhea associated with diarrheagenic Escherichia coli pathotypes (DEPs). By use of a pathogen-specific multiplex PCR, DEPs were sought in 795 stool samples, of which 125 (16%) were positive for DEP; of these, 4 represented shedding episodes and 4 parasite coinfections. Most single-DEP infections (85/117) were asymptomatic (P < 0.001), and of the 32 DEP diarrhea episodes, 41% were associated with atypical enteropathogenic E. coli (aEPEC), 37.5% with enterotoxigenic E. coli, 9% with typical EPEC, 9% with enteroinvasive E. coli, and 3% with Shiga toxin-producing E. coli strains. Among the 76 children, 54 had at least one stool positive for DEP, of which 23 experienced a DEP-associated diarrhea episode. In the last group of children, DEP infection was significantly associated with a diarrhea episode (relative risk [RR] = 2.5; 95% confidence interval [CI], 1.79 to 3.57; P < 0.001), with ETEC (RR = 2.30; 95% CI, 1.49 to 3.54; P = 0.003) and aEPEC (RR = 1.92; 95% CI, 1.23 to 3.0; P = 0.019) being the pathotypes associated with diarrhea. aEPEC-associated diarrhea episodes were frequently in the <12-month age group (RR = 2.57; 95% CI, 1.05 to 6.27; P = 0.04). aEPEC infections were distributed all year round, but associated diarrheal episodes were identified from April to October, with a May-June peak (rainy season). Most ETEC infections and diarrhea episodes characteristically occurred during the summer (rainy season), with a diarrhea peak in August. Of all DEPs, only aEPEC was associated with acute diarrhea episodes lasting 7 to 12 days (P = 0.019). DEPs are important causes of community-acquired enteric infection and diarrhea in Mexican children.     

The role of angiotensin-(1–7) receptor Mas in spermatogenesis in mice and rats

Evidence regarding the components of the renin–angiotensin (Ang) system suggests that this system plays an important role in male reproduction. However, there are few data available in the literature on the effects of Ang-(1–7) on the male reproductive system. The present study investigated the effects of the genetic deletion and chronic blockage of Ang-(1–7) receptor Mas on spermatogenesis and male fertility. The localization of Mas in mouse and rat testes was determined by binding assays and immunofluorescence, whereas the testis structure and spermatogenic process were morphologically and stereologically analysed by light microscopy. Ang-(1–7) binding and immunofluorescence revealed the presence of Mas in the testes of mice and rats. Although the total numbers of Sertoli and Leydig cells per testis and Leydig cell size were similar in both wild-type and Mas -deficient mice, Mas ^−/– animals exhibited a significant reduction in testis weight and a greater volume of apoptotic cells, giant cells and vacuoles in the seminiferous epithelium. In both mice and rats, an increased number of apoptotic cells were found during meiosis. Due to disturbed spermatogenesis, daily sperm production was markedly reduced in Mas ^−/– mice. Moreover, chronic infusion of A-779 [an Ang-(1–7) antagonist] in rats significantly increased the total number of apoptotic cells and primary spermatocytes in particular stages of spermatogenesis. Taken together, these findings strongly suggest that Ang-(1–7) receptor Mas plays an important role in the regulation of spermatogenesis.     

Natural Antibody Contributes to Host Defense against an Attenuated Brucella abortus virB Mutant

Brucella abortus is an intracellular pathogen that persists within phagocytic cells of the reticuloendothelial system. To identify in vivo interactions between B. abortus and the host that lead to persistent infection, we studied the persistence of B. abortus and an isogenic virB mutant deficient in the VirB type IV secretion system (T4SS) in knockout mice. In contrast to control mice, mice lacking B cells (Igh6^−/−) were permissive for infection with the attenuated virB mutant. To determine the basis for this phenotype, we characterized immune functions of Igh6^−/− mice in the context of B. abortus infection. Igh6^−/− mice had greater numbers of extracellular bacteria in the spleen and increased early expression of proinflammatory cytokines during B. abortus infection. Further, a virB mutant, despite its wild-type level of survival, failed to elicit microgranuloma formation in the spleens of Igh6^−/− mice, suggesting a requirement for the T4SS to elicit this pathological change. Passive transfer of immunoglobulin G from naïve mice restored the ability of Igh6^−/− mice to control the persistence of the virB mutant by a complement-independent mechanism. Further, adoptive transfer of CD11b⁺ cells from C57BL/6 mice to Igh6^−/− mice restored the ability of the knockout mice to limit the replication of the virB mutant in the spleen, suggesting that the Igh6^−/− mutation affects phagocyte function and that phagocyte function can be restored by natural antibody.Human brucellosis is a febrile disease resulting from the transmission of Brucella abortus, B. suis, B. melitensis, or B. canis from its respective zoonotic reservoir in cattle, swine, goats and sheep, or dogs (47). These pathogens are endemic in many areas of the world, including Central and South America, the Mediterranean, and Central Asia, and are responsible for an estimated 500,000 new brucellosis cases each year (1). In human brucellosis, as well as in the zoonotic reservoir species, bacteria may persist for long periods of time in the reticuloendothelial system (7). This aspect of infection can be modeled in the mouse, which has been used to identify and characterize the virulence factors involved in the systemic persistence of Brucella spp. (2, 22).One essential virulence factor of the human pathogenic Brucella species is the type IV secretion system (T4SS) encoded by the virB locus on chromosome II (18, 29, 40). The T4SS of Brucella spp., similar to those of other bacterial pathogens, mediates the translocation of proteins into host cells; however, the functions of two newly identified B. abortus T4SS substrates, VceA and VceC, is not yet known (12, 25, 39, 45, 46). In cultured macrophages and dendritic cells (DC), the T4SS is essential for the intracellular replication and persistence of B. abortus (13, 36, 40). The T4SS mediates exclusion of late endosomal/lysosomal markers from the Brucella-containing vacuole and targeting of B. abortus to exit sites of the endoplasmic reticulum, where replication occurs (5, 6, 12, 41), suggesting that T4SS effectors are involved in this function. After intraperitoneal (i.p.) inoculation of mice, the T4SS is required not for the initial systemic dissemination of B. abortus but rather for persistence in the reticuloendothelial system (31, 34). In order to better understand the interactions between the host and B. abortus that lead to the persistence of wild-type (WT) strains and the eventual clearance of virB mutants, we examined the immune mechanisms required for clearance of the virB mutant. Unexpectedly, mice lacking B cells (Igh6^−/−) were permissive for the splenic persistence of the virB mutant, while the persistence of WT B. abortus was not increased. When cultured ex vivo, macrophages from Igh6^−/− mice behaved identically to macrophages from control mice in their ability to control the intracellular replication of the virB mutant while permitting the replication of WT B. abortus (34).In this study, we attempted to pinpoint the defect in Igh6^−/− mice that renders them permissive for persistent infection by the virB mutant. Our results show that nonspecific antibody can reverse the defect of these mice in controlling virB mutant replication without affecting WT B. abortus. These results suggest that the T4SS mediates the evasion of a natural antibody-dependent immune clearance function by B. abortus during persistence in vivo.