Modifications of the responses of barrel field neurons to vibrissal stimulation during theta in the awake and undrugged rat

In partially restrained but awake and undrugged rats, excitatory unit responses of the somatic cortex barrel field to vibrissal stimulation, were recorded in two conditions: during spontaneous episodes of theta and in the absence of this rhythm. Two main variables were considered: a signal-to-noise ratio and an index of the "afferent inhibition". Both measures were extracted from peristimulus time histograms. "Theta effects" were characterized by an increase in signal-to-noise ratio and afferent inhibition. They were most important in neurons located in infragranular layers of the cortex; they went in the same direction but only approached significance in supragranular neurons; neurons of the granular layer were not affected. Spontaneous unit activity and latencies were not modified in any group. These data were obtained during a preliminary step of a sensory-sensory conditioning procedure which in some cases modified the receptive field of the neurons. Theta effects were less marked in future "conditioned" than in future non-conditioned neurons but this was probably due to the fact that conditioned neurons had significantly higher signal-to-noise ratio and afferent inhibition. The origin of these "theta effects", hippocampal versus non-hippocampal, and their functional significance, relation to selective attention, are discussed.     

Cytology of pseudomyxoma peritonei: report of two cases arising from appendiceal cystadenomas

Pseudomyxoma peritonei is the clinical term for the diffuse deposition of mucus within the peritoneal cavity secondary to a mucinous tumor of the ovary or appendix. This gelatinous ascites, or "jelly-belly," may result in death from loss of intestinal function and intestinal obstruction caused by peritoneal implants rather than visceral invasion. Microscopic evaluation of peritoneal fluid is frequently an initial diagnostic test; however, in a search of the recent literature we were surprised to find only one case report of the cytologic features. This prompted us to report the cytologic findings in the peritoneal fluid of two cases of pseudomyxoma peritonei arising from appendiceal mucinous cystadenomas.     

Serum fluctuations of total and free tryptophan levels during the menstrual cycle are related to gonadotrophins and reflect brain serotonin utilization

BACKGROUND: Serotoninergic (5-HT) neurons are suggested to regulate estrous cycle in animal models. In the present study we evaluated whether a relationship exists between the serotoninergic precursors in the central nervous system and the gonadotrophin-ovarian cyclic function. METHODS: We measured 5-HT precursors [free (FT) and total (TT) tryptophan] and LH, FSH and 17beta-estradiol (E2) levels in the serum of 15 fertile women with normal menstrual cycles during the follicular (cycle days 1-5, 7-11), mid-cycle (cycle days 14-16) and luteal (cycle days 17-19, 22-24) phases. RESULTS: TT and FT were significantly increased in the 7-11 and 17-19 cycle days and were decreased at mid-cycle (P < 0.01), with a cyclic and opposite behaviour when compared to that of FSH and LH. Indeed, correlation analysis through the matrix of mean values showed that LH was negatively correlated to TT (r = -0.636) and FT (r = -0.574), as well as FSH (TT, r = -0.655; FT, r = -0.663), and that TT and FT were positively correlated to each other (r = 0.801; P < 0.001). Furthermore, whilst the two FT peaks reached approximately the same levels in the follicular and luteal phase, TT levels were approximately 30% higher in the luteal than in the follicular phase of the cycle: thus in the first (follicular) phase FT peak was relatively higher than that of TT, whereas the contrary occurred in the second (luteal) phase of the cycle. CONCLUSIONS: Both TT and FT levels have cyclic variations throughout the menstrual cycle, being lowest at mid-cycle (14-16 cycle days), concomitant with the highest LH and FSH concentrations, and higher before and after mid-cycle phase, coinciding with the lowest circulating LH/FSH levels. Since TT and FT levels in the plasma have cyclic changes, our study: (i) suggests that a consumption of serum serotonin precursors takes place concomitant with gonadotrophin release during menstrual cycle; (ii) may represent an in vivo model to investigate this relationship in women in different physiopathological conditions.     

Seroprevalence of human herpesvirus-8 in blood donors from different geographical regions of Argentina, Brazil, and Chile

Human herpesvirus-8 (HHV-8) causes Kaposi's sarcoma (KS) and lymphoproliferative disorders in both HIV-infected and uninfected patients. HHV-8 has a worldwide occurrence but infection rates vary according to a combination of geographic and behavioral risks. The main transmission route seems to be sexual, nevertheless, nasal secretions, saliva, blood, and organ graft have been proposed. HHV-8 was postulated as a new infectious agent for screening in blood donors. The aim of this study was to evaluate the prevalence of antibodies against HHV-8 antigens in blood donors of South America. Serum samples from 2,470 blood donors from Argentina, Brazil, and Chile corresponding to five geographic regions were studied by indirect immunofluorescence assay (IFA). Seroprevalence rate was 3.7% (92/2,470; 95% CI 2.9-4.5) in the entire blood donor population distributed as follows: Argentina, 4.0% (Buenos Aires city, 4.3%; Bahia Blanca, 2.4%; and Córdoba, 4.0%), Campinas (Brazil), 2.8%; and Santiago de Chile, 3.0%. There was no difference (P>0.05) between men and women or age related, except in Brazil where positive cases were 30-49-year-old males. The present study, which includes different geographical areas of multiple countries from South America, has not been done before. The results show similar prevalence rates among the studied zones corresponding to low-prevalence regions. South America is a large sub-continent with a wide spectrum of population and geographical characteristics, thus, more HHV-8 prevalence studies should be necessary to establish possible regional differences.     

Plasmid profiles of "Campylobacter upsaliensis" isolated from blood cultures and stools of paediatric patients.

Seventy-three clinical isolates of "Campylobacter upsaliensis" were screened for the presence of plasmids. Plasmid bands were found in 68 (93%) isolates, from which 14 plasmid types were identified. Type 5 was found only in blood-culture isolates, whereas types 7-14 were found only in faecal isolates. Plasmid-free isolates and the other plasmid profiles were present in both faecal and blood isolates. The reproducibility of these profiles was largely dependent on the method of plasmid isolation. The chloroform-phenol lysis method was the most efficient and reliable method of preparing plasmid DNA for plasmid profile analysis. The success of this method may be largely attributable to two factors: (1) the efficacy of cell lysis was independent of either an alkaline agent or of heat; (2) the inactivation of nucleases by the utilisation of chloroform-phenol to lyse the cells. Furthermore, this method of plasmid DNA preparation is ideally suited for use on clinical isolates, especially when rapid plasmid profile analysis may be required.     

Evaluation of the lymphocyte blastogenic response by rapid flow analysis.

The data presented show that the blastogenic response of human peripheral lymphocytes to mitogens and specific antigens can be easily evaluated with rapid flow analysis of mithramycin stained cells. The precision, reproducibility and rapidity of the method make it highly suitable to study lymphocyte response to antigens in patient populations.     

Increased incidence of HL-A 1 and 8 in patients showing IgG or complement coating on their red cells

The incidence of HL-A antigens in patients having a variety of medical conditions, but sharing the common feature of a positive antiglobulin test of the red cells, was determined. There was a significant increase in the antigens HL-A 1 and HL-A 8 and of the 1 and 8 combination when compared with a control group. It is suggested that the presence of these antigens may predispose to autoallergy.     

Role of heparan sulphate proteoglycans as potential receptors for non-piliated Pseudomonas aeruginosa adherence to non-polarised airway epithelial cells

Tight junctions seal polarised surface epithelial respiratory cells so as to prevent the passage of bacteria and toxins through the epithelial sheet. Disruption of tight junctions, which may occur during injury and repair processes of airway epithelium, favours potential bacterial interaction with receptors from cell basolateral membranes. Earlier studies reported that non-polarised and untight epithelial respiratory cells are highly susceptible to Pseudomonas aeruginosa adherence and internalisation. As heparan sulphate proteoglycans (HSP) from cell basolateral membranes in epithelial cells without tight junctions may become accessible to bacterial ligands, the present study investigated their role as potential receptors for non-piliate P. aeruginosa ligands. Treatment of cells with heparitinase I and II significantly reduced (51.2% and 51.7%, respectively) P. aeruginosa adherence to epithelial respiratory cells without tight junctions. The internalisation of bacteria was not affected by treatment with heparitinases. Treatment of the bacteria with heparin and heparan sulphate also significantly reduced their adherence to respiratory cells (34.3% and 43.7%, respectively). Treatment of cells with other enzymes (trypsin, lipase and chondroitinase ABC) or treatment of bacteria with chondroitin-4-sulphate did not modify the adherence to respiratory cells significantly. Both affinity chromatography and Western blotting assays showed the interaction of different P. aeruginosa outer-membrane proteins (OMPs) with heparin. Several bacterial strains showed differences in their profile of heparin-binding OMPs, but all exhibited low mol. wt (< 30 kDa) reactive proteins. Reactivity of whole bacterial cells with heparin was also observed by transmission electron microscopy. These results suggest that HSP are potential receptors for P. aeruginosa adherence to non-polarised and untight epithelial respiratory cells.