Relationships between total plasma load of torquetenovirus (TTV) and TTV genogroups carried

In 239 torquetenovirus-positive people, multiple-genogroup infections were common and associated with higher viral loads than would be expected from simple additive effects. The latter observation was restricted to the infections which included both genogroups 1 and 3, pointing to the possible existence of some kind of infection facilitation between these genogroups.     

Cellular distribution of phosphofructokinase activity and implications to metabolic regulation in human breast cancer

Neoplastic cells generally present profound changes in glucose metabolism. The mechanisms underlying such process are numerous and all may involve altered cellular hormonal responses. Here we report the first evidence that cellular location of phosphofructokinase activity in human breast cancer tissues is different from the one observed in control tissues and that this phenomenon may be involved in the increased glycolytic flux observed in those cells. Through co-sedimentation techniques, we observed that 60% of phosphofructokinase activity in neoplastic tissues is located in an actin-enriched fraction, against 36% in control tissues. Additionally, metastatic tumor tissues presented a two fold increase in this particulate activity when compared to non-metastatic tumor samples. We propose that the alteration in cellular distribution of phosphofructokinase activity in human breast cancer tissues is a mechanism associated to the process of cell transformation and may be a consequence of the altered hormonal milieu observed in several types of cancer.     

Identification of vaccine candidate peptides in the NcSRS2 surface protein of Neospora caninum by using CD4+ cytotoxic T lymphocytes and gamma interferon-secreting T lymphocytes of infected holstein cattle

Previously, our laboratory showed that Holstein cattle experimentally infected with Neospora caninum develop parasite-specific CD4+ cytotoxic T lymphocytes (CTL) that lyse infected, autologous target cells through a perforin-granzyme pathway. To identify specific parasite antigens inducing bovine CTL and helper T-lymphocyte responses for vaccine development against bovine neosporosis, the tachyzoite major surface proteins NcSAG1 and NcSRS2 were targeted. In whole tachyzoite antigen-expanded bovine T-lymphocyte lines, recombinant NcSRS2 induced potent memory CD4+- and CD8+-T-lymphocyte activation, as indicated by proliferation and gamma interferon (IFN-gamma) secretion, while recombinant NcSAG1 induced a minimal memory response. Subsequently, T-lymphocyte epitope-bearing peptides of NcSRS2 were mapped by using overlapping peptides covering the entire NcSRS2 sequence. Four experimentally infected cattle with six different major histocompatibility complex (MHC) class II haplotypes were the source of immune cells used to identify NcSRS2 peptides presented by Holstein MHC haplotypes. NcSRS2 peptides were mapped by using IFN-gamma secretion by rNcSRS2-stimulated, short-term T-lymphocyte cell lines, IFN-gamma enzyme-linked immunospot (ELISPOT) assay with peripheral blood mononuclear cells, and 51Cr release cytotoxicity assay of rNcSRS2-stimulated effector cells. Four N. caninum-infected Holstein cattle developed NcSRS2 peptide-specific T lymphocytes detected ex vivo in peripheral blood by IFN-gamma ELISPOT and in vitro by measuring T-lymphocyte IFN-gamma production and cytotoxicity. An immunodominant region of NcSRS2 spanning amino acids 133 to 155 was recognized by CD4+ T lymphocytes from the four cattle. These findings support investigation of subunit N. caninum vaccines incorporating NcSRS2 gene sequences or peptides for induction of NcSRS2 peptide-specific CTL and IFN-gamma-secreting T lymphocytes in cattle with varied MHC genotypes.     

Ultrastructural Features of Neuroendocrine Differentiated Carcinomas of the Breast

The ultrastructural patterns of neuroendocrine (NE) differentiated breast carcinomas are analyzed and discussed. Reports in the literature describe wide variations in the size of observed dense-core membrane-bound granules and discrepancies in their interpretation. In the present study 24 cases of breast carcinoma with recognized morphologic, histochemical, and immunocytochemical features of NE tumors were investigated. Five different types of dense-core granules of neurosecretory (NS) type (confirmed by the ultrastructural localization of chromogranin A) and five different cell types were recognized. Some amphicrine cells were found to contain both mucin and NS granules. Another notable ultrastructural feature of breast NE carcinomas was the presence of clear vesicles of presynaptic type, which correlated with expression of synaptophysin.     

Regulation of human erythrocyte metabolism by insulin: cellular distribution of 6-phosphofructo-1-kinase and its implication for red blood cell function

Human erythrocytes are highly specialized cells whose function is oxygen transport. These cells' sole metabolic source of energy is the fermentation of glucose via glycolysis. They contain an active insulin receptor and respond to insulin by increasing phosphorylation of tyrosine residues in several proteins. However, no metabolic effects have yet been associated with activation of this receptor in human erythrocytes. Here, we show that insulin increases the rate of glycolysis in human erythrocytes. Lactate production increased 56 and 173% in the presence of 10 and 100 nM insulin, respectively. A higher insulin concentration (1000 nM) partially reversed the stimulation of glycolysis. These effects occur through activation of the key glycolytic enzyme 6-phosphofructo-1-kinase, which exhibits the same pattern of modulation by insulin as seen for glycolytic flux. This modulation also occurs physiologically since ex vivo experiments revealed 50% stimulation of 6-phosphofructo-1-kinase (PFK) activity following a high carbohydrate meal. Insulin increases phosphorylation of PFK and redistributes the enzyme in red blood cells, causing it to detach from the erythrocyte membrane: upon insulin stimulation, the amount of enzyme associated with the plasma decreases by 86%. Detachment is a common mechanism of enzyme activation. As a consequence, insulin prevents up to 68% of red cells hemolysis. These results show that insulin regulates erythrocyte glycolysis and viability and suggest that this regulation is associated to other erythrocyte functions such as oxygen transport. Finally, we suggest that this regulatory mechanism might be compromised in patients with diabetes mellitus.     

Expression of human CD81 in transgenic mice does not confer susceptibility to hepatitis C virus infection

We previously demonstrated that hepatitis C virus (HCV) binds to human CD81 through the E2 glycoprotein. Therefore, expression of the human CD81 molecule in transgenic mice was expected to provide a new tool to study HCV infection in vivo, as the chimpanzee is the only species currently available as a laboratory animal model that can be infected with HCV. We produced transgenic mice expressing the human CD81 protein in a wide variety of tissues. We confirmed binding of recombinant E2 glycoprotein to the liver tissue as well as to thymocytes and splenic lymphocytes in the transgenic mice. We inoculated chimpanzee plasma infected with HCV into these animals. None of these transgenic animals showed evidence of viral replication. Furthermore, human CD81 transgenic mice that lack expression of endogenous mouse CD81 were also resistant to HCV infection. We conclude that expression of human CD81 alone is insufficient to confer susceptibility to HCV infection in the mouse. The presence of additional possible factors for HCV infection is discussed.