Soluble antigens from group B streptococci induce cytokine production in human blood cultures.

Group B streptococcal antigens stimulated tumor necrosis factor alpha (TNF-alpha), interleukin-1 (IL-1), and IL-6 production in human blood cultures in a concentration- and time-dependent fashion. The minimal concentrations of type-specific polysaccharides, lipoteichoic acid, and group-specific polysaccharide required to produce these effects were, respectively, 0.01, 1, and 10 microg/ml. Cell separation experiments indicated that monocytes were the cell type mainly responsible for cytokine production. Time course studies indicated that TNF-alpha was released before the other cytokines. TNF-alpha, however, did not appear to directly induce IL-1beta, as shown by blockade experiments with anti-TNF-alpha antibodies. IL-6 levels were moderately but significantly decreased by anti-TNF-alpha. These data indicate that several products from group B streptococci are able to directly stimulate human monocytes to release TNF-alpha, IL-1beta, and IL-6. These findings may be clinically relevant, since proinflammatory cytokines can mediate pathophysiologic changes during sepsis.     

Infection of Lymnaea cubensis by Fasciola hepatica in a high altitude region in Venezuela

Lymnaea cubensis is the vector in a region of distome infection in Trujillo State at more than 1000 m altitude where almost all bovines are infected. A quarter of the molluscs were infected with a mean number of 20 rediae per infected molluc each redia capable of producing 16 cercariae. Prevalence of infection increases with size of molluse and is highest in those 4 to 5 mm long. However, Lymnaea as small as 3 mm produce cercariae and molluscicide treatments should be begun as soon as forms of this size appear.     

Expression of Brachyury during development of the dendrobatid frog Colostethus machalilla.

The expression of Brachyury (Bra) during development of Colostethus machalilla was analyzed with a polyclonal antibody. The observed molecular mass of Bra was of 48 kDa, as in Xenopus laevis. During cleavage, low levels of Bra were expressed. In contrast, in the blastula Bra became up-regulated, and Bra protein was present in a wide ring of surface cells. The surface expression of Bra disappeared in the gastrula, and a new ring of Bra-positive nuclei was detected in deep cells around the closing blastopore. The C. machalilla external and internal rings of Bra-positive nuclei apparently mark the prospective mesoderm in the blastula and gastrula, respectively. The two Bra expression rings were dissociated in time in the fairly slow developing embryos of this frog. Brachyury expression in the notochord became visible only after the blastopore closed, in contrast with X. laevis. In addition, Bra expression in the notochord indicated that dorsal convergence and extension occurred after blastopore closure. The C. machalilla Bra-positive notochord was originally exposed on the gastrocoel roof, in agreement with a superficial component of the prospective mesoderm.     

Cellular mechanisms of the adjuvant activity of the flagellin component FljB of Salmonella enterica Serovar Typhimurium to potentiate mucosal and systemic responses

An expanding area of interest is the utilization of microbe-based components to augment mucosal and systemic immune responses to target antigens. Thus, the aim of the present study was to assess if the flagellin component FljB from Salmonella enterica serovar Typhimurium could act as a mucosal adjuvant and then to determine the cellular mechanism(s) by which FljB mediates its adjuvant properties. To determine if FljB could act as a mucosal adjuvant, mice were immunized by the intranasal (i.n.) route with antigen alone or in conjunction with FljB. Additionally, we assessed how FljB affected the levels of the costimulatory molecules B7-1 and B7-2 on dendritic cells by flow cytometry and determined the functional role these costimulatory molecules played in the adjuvant properties of FljB in vivo. Mice immunized by the i.n. route with antigen and FljB exhibited significantly elevated levels of mucosal and systemic antibody and CD4(+)-T-cell responses compared to mice given antigen only. Stimulation of dendritic cells in vitro with FljB resulted in a pronounced increase in the surface expression of B7-1 and B7-2. The percentage of dendritic cells expressing B7-2 but not B7-1 increased significantly when stimulated with FljB over a concentration range of 10 to 10,000 ng/ml. Immunization of wild-type and B7-1, B7-2, and B7-1/2 knockout mice by the i.n. route revealed that the ability of FljB to increase B7-2 expression is largely responsible for its adjuvant effect in vivo. These findings demonstrate that FljB can act as an effective mucosal adjuvant and that its ability to enhance the level of B7-2 expression is predominantly responsible for its adjuvant properties.     

Thyroid health status of ammonium perchlorate workers: a cross-sectional occupational health study

Since pharmaceutical exposures to perchlorate are known to suppress thyroid function in patients with hyperthyroidism, a study of employees at a perchlorate manufacturing plant was conducted to assess whether occupational exposure to perchlorate suppresses thyroid function. Exposure to perchlorate was assessed by measurement of ambient air concentrations of total and respirable perchlorate particles, and systemic absorption was assessed by measurement of urinary perchlorate excretion. Airborne exposures ranged from 0.004 to 167 mg total particulate perchlorate per day. Urinary perchlorate measurements demonstrated that exposure to the airborne particulate perchlorate resulted in systemic absorption. Workers were grouped into four exposure categories with mean absorbed perchlorate dosages of 1, 4, 11 and 34 mg perchlorate per day. Thyroid function was assessed by measurement of serum thyroid-stimulating hormone, free thyroxine index, thyroxine, triiodothyronine, thyroid hormone binding ratio, thyroid peroxidase antibodies, and by clinical examination. No differences in thyroid-function parameters were found between the four groups of workers across approximately three orders of magnitude of exposure and of dose. Thus human thyroid function was not affected by these levels of absorbed perchlorate. In addition, no clinical evidence of thyroid abnormalities was found in any exposure group. The blood-cell counts were normal in all groups, indicating no evidence of hematotoxicity in this exposure range. The absence of evidence of an effect on thyroid function or blood cells from occupational airborne perchlorate exposure at a mean absorption of 34 mg/day demonstrates a no-observed-adverse-effect-level (NOAEL) that can assist in the evaluation of human health risks from environmental perchlorate contamination.     

Hepatitis G virus infection in hemodialysis patients and its relationship with hepatitis C virus infection

Our aim was to study the characteristics of hepatitis G virus (HGV) infection in hemodialysis (HD) patients. We evaluated 108 patients from two different units (A: 67 patients; B: 41 patients). HGV RNA and HCV RNA were detected by PCR. Nineteen patients (17.6%) were HGV RNA positive (20.9% in unit A and 12.2% in unit B (NS)). HCV RNA was positive in 19 patients (17.6%) (28.4% in unit A and 0 in unit B (p < 0.01)). Eight patients were HGV RNA and HCV RNA positive (group I), 11 HGV RNA positive (group II), 11 HCV RNA positive (group III), and 78 negative for both viruses (group IV). Time on HD was 51.3 +/- 37.0 months for group I, 36.0 +/- 27.9 months for group II, 63.5 +/- 40.2 months for group III, and 26.4 +/- 27.1 months for group IV (p < 0.01 for I and III). Seven patients (87.5%) from group I, 9 (81.8%) from group II, 10 (90.9%) from group III, and 44 (56.4%) from group IV had a history of transfusion (p < 0.03 for I, II and III). Two patients (25%) from group I, none from group II, 5 (45.4%) from group III, and 6 (7.7%) from group IV had chronic ALAT elevation (p < 0.01 for I and III). We conclude that HGV infection was frequent in our HD patients, related to transfusions and independent of HCV prevalence, and that HGV infection itself was not a cause of ALAT elevation suggesting chronic hepatitis.     

Liver and kidney damage induced by 4-aminopyridine in a repeated dose (28 days) oral toxicity study in rats: Gene expression profile of hybrid cell death

4-Aminopyridine (4-AP) is an orphan drug indicated for the treatment of neuromuscular disorders. There is a great controversy around the use of this drug because of its narrow safety index and because a large number of adverse effects have been reported. Moreover, it was shown to induce cell death in different cell lines, being reported mainly apoptosis and necrosis as the principal pathways of cell death mediated by blockage of K channels or the Na, K-ATPase, but until now it was not described in vivo cell death induced by 4-aminipyridine. To provide new subchronic toxicity data and specifically, evaluate if 4-AP is able to induce in vivo cell death process and the main pathways related to it, a repeated dose (28 days) oral toxicity study, at therapeutic range of doses, was conducted in rats. The anatomical pathology, the biochemical and hematological parameters were analyzed and a real-time PCR array analysis was developed with an Ingenuity Pathway Analysis (IPA). The leucocytes number, the lactate dehydrogenase (LDH) and aspartate aminotransferase (AST) enzymatic activity were increased at all dose but the erythrocytes number, the hemoglobin concentration, the alkaline phosphatase (FAL) and alanine aminotransferase (ALT) enzymatic activity were increased only at highest dose studied. However, glucose levels decreased at all doses. The biochemical results are indicative of hepatic damage. The anatomy pathology studies showed cell death only on liver and kidney, and the real-time PCR array on liver tissue expressed a gene expression profile of necrotic and apoptotic induced cell death. The present work shows for the first time in vivo cell death on liver and kidney with features of apoptosis and necrosis induced by 4-AP and the gene expression profile shows that the cell death is mediated by necrotic and apoptotic pathways that support this finding.