Electrochemical study of endodontic silver cones used in root canal therapy

In previous studies it was observed that endodontic silver cones placed in fine canals became dislodged as a result of corrosion. To investigate the corrosion of high purity silver, potentiostatic and potentiodynamic electrochemical techniques were used. Triangular potential sweeps made in physiological solutions and human plasma showed similar potential-current relationships. However, in human plasma, peak currents were lower and peak potentials were more anodic than those observed in the physiological solutions. The electron microprobe analysis and the EDAX of the film formed in the biological fluids revealed the presence of silver and chloride and a certain amount of carbon. The addition of small quantities of Na2S to the physiological solutions favoured metal dissolution and promoted the formation of a mixed film of AgCL and Ag2S. According to these results chloride and sulphide anions seem to be particularly aggressive towards the metal surface in implanted silver cones. Precautions to avoid direct contact of the cones with saliva and tissue fluids must be taken. Fractures and discontinuities present in the cement considerably increase the corrosion risks.     

Stapled Hemorrhoidopexy: A Prospective Study From Pathology to Clinical Outcome

Stapled hemorrhoidopexy is widely accepted to treat hemorrhoids, but serious complications have been reported. In this prospective audit, we correlated clinical outcome with pathological findings. From January 2003 to April 2007, 94 patients underwent hemorrhoidopexy. Macroscopic appearance of the specimen (shape, size, and depth) was recorded. Microscopically, the presence of columnar, transitional, and squamous epithelium, the involvement of circular/longitudinal smooth muscle, and features of mucosal prolapse were assessed. Clinical outcome was evaluated by a validated questionnaire. Postoperative pain, secretion, and bleeding durations were 12.7 +/− 10.6, 5.6 +/− 9.6, and 6.3 +/− 8.4 days. Patient’s return to work averaged 16.7 +/− 10.7 days. Fissure, skin tags, and anal strictures were observed in 23.4%. Seven patients experienced pain for a significantly longer period of time. All specimens contained columnar mucosa, but 29.8% contained columnar and transitional epithelium and 12.8% contained columnar, anal transitional, and stratified squamous epithelium. Smooth muscle was observed in 62.7%. Pain was significantly increased if transitional epithelium was present in the specimen. No correlation or differences were observed if smooth muscle was present, although postoperative bleeding was more frequent. Hemorrhoidopexy is safe and effective. The specimen should always be sent for pathology examination. Only columnar epithelium should be present and, although the presence of smooth muscle does not influence the outcome in terms of functional results, its presence may play a role in postoperative bleeding. Presented as poster at the Digestive Disease Week, May 2007, Washington, USA     

Hepatitis B and Delta virus infection among heterosexuals,homosexuals and bisexual men

The hepatitis B virus (HBV) and hepatitis Delta virus (HDV) infection rates were estimated in patients attending a venereal disease outpatient clinic: 759 heterosexuals and 154 homosexual-bisexual men. The anti-HBC prevalence was higher in homo-bisexual men (68.8 per 100) than in heterosexuals (41.8 per 100), whereas HBsAg was roughly the same in the two groups (about 6 per 100). The anti-HBc prevalence rate among heterosexuals was higher than that estimated in hospital personnel from the same geographical area. A positive association between anti-HBc prevalence and present or past sexually transmitted diseases (STD) was found among homo-bisexual men. Anti-HBc was also positively associated with herpes simplex type 2 antibodies in both heterosexuals and homo-bisexual men. These data are consistent with the hypothesis that sexual behavior also plays a role in the spread of infection among heterosexuals. Ten of the 46 HBsAg-positive subjects were anti-HDV positive: 6 of the 36 heterosexuals and 4 of the 10 homosexuals. All HDV-positive subjects had present or past STDs. These findings suggest sexual transmission of HDV infection.     

Developmental and age-related changes in D1-dopamine receptors and dopamine content in the rat striatum

The relationship between the postnatal development of dopaminergic (DAergic) nerve endings and the maturation of D1 DA receptors in the rat striatum was analyzed by measuring the content of DA and dihydroxyphenylacetic acid (DOPAC), two biochemical markers of DAergic nerve terminal proliferation, and the ontogenetic changes in [3H]SCH 23390 binding sites. DA-stimulated adenylate cyclase (AC) activity was also measured in order to characterize the coupling of [3H]SCH 23390 binding sites to the responses mediated by the activation of D1 DA receptors. Striatal levels of DA and DOPAC, as well as the density and affinity of [3H]SCH 23390 binding sites and DA-stimulated AC activity were also measured in senescent rats. The striatal content of DA increased slowly after birth, reaching adult levels by postnatal day 60 and remaining constant through adulthood and senescence (up to 20 months of age). The density of [3H]SCH 23390 binding sites increased 14-fold from birth to postnatal day 35, when a peak value was reached, whereas a significant decrease was observed in the striatum of aged rats. In contrast, the affinity of D1 DA receptors for [3H]SCH 23390 remained unchanged from birth through senescence. The stimulation of cyclic AMP formation induced by 100 microM DA increased 4-fold from birth to postnatal day 14, when the maximal responsiveness to DA was observed and then returned to adult levels. No significant alterations were observed in the Km values during development, whereas the stimulatory effect of 100 microM DA on AC activity was significantly decreased in senescent rats.(ABSTRACT TRUNCATED AT 250 WORDS)     

Neuropharmacology of several beta-carboline derivatives and their 9-acetylated esters. In vivo versus in vitro studies in the rabbit

The effects of 3-methoxycarbonyl- (beta-CCM, Ia), 3-ethoxycarbonyl- (beta-CCE, Ic), 3-propoxycarbonyl- (PrCC, Ie), 3-N-methylcarboxamido- (FG-7142, Ig) beta-carboline and 2-acetyl-3-methoxycarbonyl-1,2-dihydro-beta-carboline (IIa) as well as of their corresponding 9-acetyl derivatives (Ib, Id, If, Ih and IIb) have been studied in rabbits. In addition, the effects of 6,7-dimethoxy-4-ethyl-3-methoxycarbonyl-beta-carboline (DMCM) have also been studied. In in vitro studies, these drugs compete with 3H-diazepam to benzodiazepine (BDZ) receptor in membrane preparations from brain cortex. The values of IC50 are in the nanomolar range without significant differences between the acetyl derivatives and their congeners only compound If shows a 10-fold decrease of the binding capacity in respect to its congener Ie. In the presence of 10(-5) M GABA, a decrease in the binding capacity for DMCM, Ia, Ic and Ig and an increase for If are observed. In vivo studies show that DMCM, Ia, Ib, IIa and IIb elicit three dose-dependent stages of electrocortical changes (trains of slow waves, trains of spike-and-wave complexes and "grand-mal" seizures). Compounds Ic, Id and Ig elicit only the first two stages. Compound Ih elicits only the first stage. While compound Ie does not affect the EEG pattern, its 9-acetyl derivative If induces changes (cortical spindles and disruption of the hippocampal theta waves) characteristic of agonist ligands of BDZ receptor. These findings confirm that the efficacy of compounds DMCM, Ia, Ic, Id, Ig and Ih as inverse agonists of BDZ receptor in the EEG paradigm parallels the reduction of their apparent binding affinity in the presence of GABA. The 9-acetylated compounds may be more inverse agonist in vivo than predicted from the in vitro findings, due to hydrolysis in the plasma.     

Cryptosporidium parvum-specific CD4 Th1 cells from sensitized donors responding to both fractionated and recombinant antigenic proteins

T-cell-mediated immunity plays a central role in the host response to Cryptosporidium parvum. Human T-cell clones (TCC) were isolated from peripheral blood mononuclear cells of five healthy donors with prior cryptosporidiosis by use of a C. parvum crude extract, two antigen fractions obtained by ion-exchange chromatography (IEC1 and IEC2), and two recombinant peptides (SA35 and SA40) from C. parvum sporozoites. The T-cell lines derived from the one recently infected donor had a higher proportion (26 to 38%) of T cells exhibiting the gamma/delta T-cell receptor (gamma/delta-TCR) than those from donors who had recovered from cryptosporidiosis several years earlier, suggesting that the gamma/delta T-cell population is involved in the early stage of the infection. The specific TCC had the alpha/beta-TCR, had the phenotype CD45RO(+) CD4(+) CD8(-), and were characterized by either hyperproduction of gamma interferon (IFN-gamma) alone, with a Th1 profile, or IFN-gamma hyperproduction together with interleukin-4 (IL-4) or IL-5 production, with a Th0 profile. SA35, SA40, IEC1, and IEC2 may be considered good targets of the cellular response against C. parvum and may play a role in maintaining the T-cell-mediated memory response to this parasite. Furthermore, the SA35 and SA40 peptides may be regarded as immunodominant antigens involved in the maintenance of the T-cell response in healthy C. parvum-sensitized persons.     

A high frequency of the A30, B18, DR3, DRw52, DQw2 extended haplotype in Sardinian celiac disease patients: Further evidence that disease susceptibility is conferred by DQ A1*0501, B1*0201

This study characterizes by serological and molecular methods the HLA class I and class II alleles in a group of celiac disease children, their parents and a control group of Sardinian descent. We found the DR3-DQw2 haplotype in all patients which was, in almost all cases (84%), associated with the HLA-A30, B18, DR3, DRw52, DQw2 extended haplotype named "Sardinian haplotype" because of its frequency (12-15%) in this Caucasian population. This is the first time that this DQw2-linked haplotype has been reported with such a high frequency in CD. However, no different distribution of "Sardinian haplotype" was found comparing CD patients with 91 haplotyped DQw2-positive controls. This finding indicates that the DQw2 antigen in Sardinians is almost always associated with the A30, B18, DR3, DRw52, DQw2 extended haplotype. The DQA1 and DQB1 second exon sequence analysis of the B18,DR3 and B8,DR3 haplotypes showed the DQA1*0501 and DQB1*0201 alleles which shared the already published sequences. DPB1 subtyping showed the DPB1*0301 allele more frequently (p less than 0.005) in CD patients but this difference was no longer significant when patients and controls, both heterozygous for the DR3-DQw2 haplotype, were compared. We suggest that the divergent HLA extended haplotypes and DP allele associated with CD, described in different Caucasian populations, can be explained by the particular DQw2 linkage disequilibrium in each population.     

Plasma and Urinary Amino Acid-Derived Catabolites as Potential Biomarkers of Protein and Amino Acid Deficiency in Rats

Objective: Dietary intakes must cover protein and essential amino acid (EAA) requirements. For this purpose, different methods have been developed such as the nitrogen balance method, factorial method, or AA tracer studies. However, these methods are either invasive or imprecise, and the Food and Agriculture Organization of the United Nations (FAO, 2013) recommends new methods and, in particular, metabolomics. The aim of this study is to determine total protein/EAA requirement in the plasma and urine of growing rats. Methods: 36 weanling rats were fed with diets containing 3, 5, 8, 12, 15, and 20% protein for 3 weeks. During experimentation, urine was collected using metabolic cages, and blood from the portal vein and vena was taken at the end of the experiment. Metabolomics analyses were performed using LC-MS, and the data were analyzed with a multivariate analysis model, partial least Squares (PLS) regression, and independent component-discriminant analysis (ICDA). Each discriminant metabolite identified by PLS or ICDA was tested by one-way ANOVA to evaluate the effect of diet. Results: PLS and ICDA allowed us to identify discriminating metabolites between different diet groups. Protein deficiency led to an increase in the AA catabolism enzyme systems inducing the production of breakdown metabolites in the plasma and urine. Conclusion: These results indicate that metabolites are specific for the state of EAA deficiency and sufficiency. Some types of biomarkers such as AA degradation metabolites appear to be specific candidates for protein/EAA requirement.     

Clonal composition and persistence of antigen-specific circulating T follicular helper cells

T follicular helper (T_FH) cells play an essential role in promoting B cell responses and antibody affinity maturation in germinal centers (GC). A subset of memory CD4⁺ T cells expressing the chemokine receptor CXCR5 has been described in human blood as phenotypically and clonally related to GC T_FH cells. However, the antigen specificity and relationship of these circulating T_FH (cT_FH) cells with other memory CD4⁺ T cells remain poorly defined. Combining antigenic stimulation and T cell receptor (TCR) Vβ sequencing, we found T cells specific to tetanus toxoid (TT), influenza vaccine (Flu), or Candida albicans (C.alb) in both cT_FH and non-cT_FH subsets, although with different frequencies and effector functions. Interestingly, cT_FH and non-cT_FH cells specific for C.alb or TT had a largely overlapping TCR Vβ repertoire while the repertoire of Flu-specific cT_FH and non-cT_FH cells was distinct. Furthermore, Flu-specific but not C.alb-specific PD-1⁺ cT_FH cells had a “GC T_FH-like” phenotype, with overexpression of IL21, CXCL13, and BCL6. Longitudinal analysis of serial blood donations showed that Flu-specific cT_FH and non-cT_FH cells persisted as stable repertoires for years. Collectively, our study provides insights on the relationship of cT_FH with non-cT_FH cells and on the heterogeneity and persistence of antigen-specific human cT_FH cells.