Helicobacter hepaticus hydrogenase mutants are deficient in hydrogen-supported amino acid uptake and in causing liver lesions in A/J mice

Helicobacter hepaticus, a causative agent of chronic hepatitis and hepatocellular carcinoma in mice, expresses a nickel-containing hydrogen-oxidizing hydrogenase enzyme. Growth of a hyaB gene-targeted mutant was unaffected by the presence of hydrogen, unlike the wild-type strain, which showed an enhanced growth rate when supplied with H(2). Hydrogenase activities in H. hepaticus were constitutive and not dependent on the inclusion of H(2) during growth. Addition of nickel during growth significantly stimulated both urease (for wild-type and hyaB) and hydrogenase (for wild-type) activities. In a 5-h period, the extent of (14)C-labeled amino acid uptake by the wild type was markedly enhanced in the presence of hydrogen and was >5-fold greater than that of the hyaB mutant strain. In the presence of H(2), the short-term whole-cell amino acid uptake V(max) of the parent strain was about 2.2-fold greater than for the mutant, but the half-saturation affinity for amino acid transport was the same for the parent and mutant strain. The liver- and cecum-colonizing abilities of the strains was estimated by real-time PCR quantitation of the H. hepaticus-specific cytolethal distending toxin gene and showed similar animal colonization for the hyaB mutant and the wild type. However, at 21 weeks postinoculation, the livers from mice inoculated with wild type exhibited moderate lobular lymphoplasmacytic hepatitis with hepatocytic coagulative necrosis, but the hydrogenase mutants exhibited no histological evidence of lobular inflammation or necrosis.     

Rat bone marrow stromal cell osteogenic differentiation and fibronectin adsorption on chitosan membranes: the effect of the degree of acetylation

Cell adhesion, migration, and proliferation of a few anchorage-dependent cells cultured on chitosan (Ch) matrices are influenced by the degree of N-acetylation (DA) of Ch. In the present work, we examined the influence of the DA on the attachment, spreading, proliferation, and osteogenic differentiation of rat bone marrow stromal cells (rBMSCs). Ch membranes were characterized in terms of surface morphology, roughness, and wettability, and in terms of adsorption of an adhesive protein, fibronectin (Fn). Chs with DAs in the range of 4 to 49% were used. Among the Ch samples, the DA of 4% led to the highest Fn surface concentration, both from single protein solution and from diluted serum. Furthermore, the levels of Fn adsorbed from serum found for this DA were threefold higher than for the tissue culture polystyrene control, indicating that in the presence of competitive proteins Ch is more specific toward Fn adsorption than tissue culture polystyrene. rBMSCs cultured on Ch carrying a DA of 4% were able to spread, proliferate, and differentiate, reaching a higher level of osteogenic differentiation than on the control, despite the lower cell attachment observed for all Ch samples. Because the Ch sample with a DA of 4% showed the highest Fn adsorption from serum, we suggest that cell adhesion, spreading, and osteogenic differentiation of rBMSCs on Ch may be mediated by the adsorbed layer of Fn.     

Basal cell adenocarcinoma of the palate with squamous metaplasia

Basal cell adenocarcinoma is a rare salivary gland tumour, especially in minor glands. The clinical, histological, and immunohistochemical features of a case involving the palate are described. Formalin fixed, paraffin embedded sections of the tumour were examined in haematoxylin and eosin (H&E) sections and also using immunostaining for cytokeratins 7, 8, 13, 14, 18, 19, vimentin, muscle specific actin (HHF35), and laminin. H&E sections showed that the tumour was composed mainly of basaloid cells and a striking feature was the presence of squamous metaplasia. Neural invasion was also conspicuous. Immunohistochemical reactions indicated that cytokeratin 14 was expressed by all tumour cells and vimentin by all cells except those in the areas of squamous metaplasia. The remaining cytokeratins and actin were present in some of the tumour cells, while laminin showed discreet positivity around cell arrangements. The foci of squamous metaplasia and the immunohistochemical findings are helpful in distinguishing basal cell adenocarcinoma from other salivary gland tumours which show basaloid cells.     

Frequent recovery of a single clonal type of multidrug-resistant Staphylococcus aureus from patients in two hospitals in Taiwan and China

One hundred thirty-two methicillin-resistant Staphylococcus aureus (MRSA) isolates recovered from patients with S. aureus infections between January 1998 and February 1999 in two hospitals, one located in Taipei, Taiwan, and another in Nanjing, People's Republic of China, were examined for antibiotic susceptibility and for clonal type by a combination of three methods: hybridization of ClaI restriction digests with mecA- and Tn554-specific DNA probes and pulsed-field gel electrophoresis of chromosomal SmaI digests. Selected isolates representing each clonal type were also analyzed by spaA typing, multilocus sequence typing, and a multiplex PCR method capable of identifying the structural type of the staphylococcal cassette chromosome mec (SCCmec) carried by the bacteria. The overwhelming majority of isolates (126 of 132 or 95%) belonged to minor variants of a single clonal type resembling the Brazilian and Hungarian epidemic MRSA clones, which showed a common spaA type and which were either sequence type 239 (ST239) or ST241 (a single-locus variant of ST239) in association with SCCmec type III or IIIA.     

Deposition and passage of transthyretin through the blood-nerve barrier in recipients of familial amyloid polyneuropathy livers

Familial amyloid polyneuropathy (FAP) is characterized by deposition of mutated transthyretin (TTR) in the peripheral nervous system. Prior to amyloid fibrils, nonfibrillar TTR aggregates are deposited inducing oxidative stress with increased nitration (3-NT). As the major source of TTR is the liver, liver transplantation (LT) is used to halt FAP. Given the shortage of liver donors, domino LT (DLT) using FAP livers is performed. The correlation between TTR deposition in the skin and nerve was tested in biopsies from normal individuals, asymptomatic carriers (FAP 0) and FAP patients; in FAP 0, nonfibrillar TTR was observed both in the skin and nerve in the same individuals; in patients, amyloid was detected in both tissues. The occurrence of amyloidosis in recipients of FAP livers was evaluated 1-7 years after DLT: TTR deposition occurred in the skin 3 years after transplantation either as amyloid or aggregates; in one of the recipients, fibrillar TTR was present in the epineurium 6 years after DLT. Deposits were scarce and 3-NT immunostaining was irrelevant. Nerve biopsies from DLT recipients had no FAP-related neuropathy. Our findings suggest that TTR amyloid formation occurs faster than predicted and that TTR of liver origin can cross the blood-nerve barrier. Recipients of FAP livers should be under surveillance for TTR deposition and tissue damage.     

Lymphocyte traffic is modified in vivo by anti-laminin antibody.

Data emerging from recent in vivo and in vitro studies are pointing to basement membrane and other extra cellular matrix (ECM) components as likely determinants of specific lymphocyte entry and positioning in lymphoid tissues. In this report, the relevance of this notion is investigated in T-cell deficient (B) rat recipients of cardiac allografts, using an anti-laminin (LN) antibody as the probe. The 6-hr migration patterns of 111In-labelled peripheral lymph node (PLN) cells were followed in groups of engrafted B hosts treated with rabbit anti-rat LN antibody or rabbit serum. The accumulation of adoptively transferred cells in PLN and cardiac allografts of recipients pretreated with anti-LN antibody was significantly decreased compared to controls (P less than 0.05 and P less than 0.001, respectively). The transferred cells also localized in slightly lower numbers in the spleens and lungs of anti-LN conditioned rats; no differences were seen in the clearance of lymphocytes from peripheral blood, or their sequestration in liver and kidney. These data provide the first in vivo evidence that an antibody against LN selectively affects lymphocyte traffic. The results reinforce the notion that basement membrane components could be critical in 'directing' lymphocyte migration in vivo.     

Modulation of acute visceral nociception and bladder inflammation by plant triterpene, α, β-amyrin in a mouse model of cystitis: role of tachykinin NK<Subscript>1</Subscript>-receptors,and K<Superscript>+</Superscript><Subscript>ATP</Subscript> channels

Objective and design: We previously described the visceral antinociceptive property of α, β-amyrin in a mouse model of cystitis induced by cyclophosphamide (CPM). This study examined the contribution of vanilloid-1 (TRPV1), peripheral NK1 receptors to CPM-evoked nociceptive behaviors and bladder edema, and its possible modulation by α, β-amyrin. Methods: The effect of α, β-amyrin (10, 30, and 100 mg/kg, p. o.) and N-acetylcysteine (NAC) on CPM (400 mg/kg, i. p.)-induced cystitis was studied in mice. Sensory deafferentation was done by a high dose capsaicin. The parameters analysed were: CPM-evoked noxious behaviors, bladder edema, vascular permeability, and NK₁ immunoreactivity. To assess the role of K⁺ _ATP channels in α, β-amyrin effect, animals were pretreated with glibenclamide. Results: α, β-amyrin (30 and 100 mg/kg) and NAC significantly (p < 0.01) suppressed the visceral pain-related behaviors and NK₁ immunoreactivity, but bladder edema was reduced weakly. Glibenclamide reversed the effects of α, β-amyrin. Sensory deafferentation by capsaicin significantly reduced the nociceptive responses and the NK₁ immunoreactivity to noxious stimulation by CPM. Conclusions: α, β-amyrin attenuates CPM-induced visceral pain and bladder edema by mechanisms that involve, at least in part, a block either of Substance P release or its receptor function, and partly by opening K⁺ _ATP channels. Received 13 February 2007; returned for revision 13 April 2007; accepted by G. Geisslinger 14 May 2007     

<Emphasis Type="Italic">TCF7L2</Emphasis>variant genotypes and type 2 diabetes risk in Brazil: significant association,but not a significant tool for risk stratification in the general population

Background  

Genetic polymorphisms of the TCF7L2 gene are strongly associated with large increments in type 2 diabetes risk in different populations worldwide. In this study, we aimed to confirm the effect of the TCF7L2 polymorphism rs7903146 on diabetes risk in a Brazilian population and to assess the use of this genetic marker in improving diabetes risk prediction in the general population.     

Inflammatory mediators are insufficient for full dendritic cell activation and promote expansion of CD4+ T cell populations lacking helper function

Dendritic cells (DCs) can be activated directly by triggering of receptors for pathogens or, indirectly, by exposure to inflammatory signals. It remains unclear, however, whether the two pathways result in qualitatively similar DCs or lead to equivalent adaptive immune responses. Here we report that indirect activation by inflammatory mediators generated DCs that supported CD4(+) T cell clonal expansion but failed to direct T helper cell differentiation. In contrast, exposure to pathogen components resulted in fully activated DCs that promoted T helper responses. These results indicate that inflammation cannot substitute for contact with pathogen components in DC activation and suggest that the function of pattern recognition by DCs is to couple the quality of the adaptive immune response to the nature of the pathogen.     

Clonal Distribution of Methicillin-Resistant Staphylococcus aureus in Poland

We report on a study of 158 methicillin-resistant Staphylococcus aureus (MRSA) clinical isolates obtained from 1990 to 1996 in 18 different hospitals in Poland. All isolates were recovered from infection and carriage sites of patients, carriage sites of health care personnel, and hospital environment samples. Fifty-seven MRSA strains described here were studied previously and these were divided into two different clusters according to the degree of heterogeneity of methicillin resistance expression. The aim of this study was to extend the correlation between the two clusters and identify the clonal identities among all isolates by a combination of different methodologies: (i) analysis of mecA polymorphs and Tn554 insertion patterns and (ii) determination of pulsed-field gel electrophoresis patterns of chromosomal SmaI digests. Ninety-seven of 158 strains showed a heterogeneous expression of resistance to methicillin. Among these, 75 (77.3%) were ClaI-mecA type I, ClaI-Tn554 type NH (NH, no homology with transposon Tn554), and pulsed-field gel electrophoresis (PFGE) pattern A (I::NH::A); 10 isolates were III::B::M (10.3%); and the remaining clones included a few or single isolates. The isolates with homogeneous expression of resistance to methicillin (n = 61) were predominantly ClaI-mecA type III (49 of 61 [80.3%]) but had great variability in their ClaI-Tn554 and PFGE patterns. This study confirmed the existence of two main clusters of MRSA in Poland.