Force-dependent polymorphism in type IV pili reveals hidden epitopes

Through evolution, nature has produced exquisite nanometric structures, with features unrealized in the most advanced man-made devices. Type IV pili (Tfp) represent such a structure: 6-nm-wide retractable filamentous appendages found in many bacteria, including human pathogens. Whereas the structure of Neisseria gonorrhoeae Tfp has been defined by conventional structural techniques, it remains difficult to explain the wide spectrum of functions associated with Tfp. Here we uncover a previously undescribed force-induced quaternary structure of the N. gonorrhoeae Tfp. By using a combination of optical and magnetic tweezers, atomic force microscopy, and molecular combing to apply forces on purified Tfp, we demonstrate that Tfp subjected to approximately 100 pN of force will transition into a new conformation. The new structure is roughly 3 times longer and 40% narrower than the original structure. Upon release of the force, the Tfp fiber regains its original form, indicating a reversible transition. Equally important, we show that the force-induced conformation exposes hidden epitopes previously buried in the Tfp fiber. We postulate that this transition provides a means for N. gonorrhoeae to maintain attachment to its host while withstanding intermittent forces encountered in the environment. Our findings demonstrate the need to reassess our understanding of Tfp dynamics and functions. They could also explain the structural diversity of other helical polymers while presenting a unique mechanism for polymer elongation and exemplifying the extreme structural plasticity of biological polymers.     

Non-suppressive regulatory T cell subset expansion in pulmonary arterial hypertension

Regulatory T cells (Tregs) have been reported to play a pivotal role in the vascular remodeling of pulmonary arterial hypertension (PAH). Recent studies have revealed that Tregs are heterogeneous and can be characterized by three phenotypically and functionally different subsets. In this study, we investigated the roles of Treg subsets in the pathogenesis of PAH in eight patients with PAH and 14 healthy controls. Tregs and their subsets in peripheral blood samples were analyzed by flow cytometry. Treg subsets were defined as CD4⁺CD45RA⁺FoxP3^low resting Tregs (rTregs), CD4⁺CD45RA^?FoxP3^high activated Tregs (aTregs), and CD4⁺CD45RA^?FoxP3^low non-suppressive Tregs (non-Tregs). The proportion of Tregs among CD4⁺ T cells was significantly higher in PAH patients than in controls (6.54 ± 1.10 vs. 3.81 ± 0.28 %, p < 0.05). Of the three subsets, the proportion of non-Tregs was significantly elevated in PAH patients compared with controls (4.06 ± 0.40 vs. 2.79 ± 0.14 %, p < 0.01), whereas those of rTregs and aTregs were not different between the two groups. Moreover, the expression levels of cytotoxic T lymphocyte antigen 4, a functional cell surface molecule, in aTregs (p < 0.05) and non-Tregs (p < 0.05) were significantly higher in PAH patients compared with controls. These results suggested the non-Treg subset was expanded and functionally activated in peripheral lymphocytes obtained from IPAH patients. We hypothesize that immunoreactions involving the specific activation of the non-Treg subset might play a role in the vascular remodeling of PAH.     

Myocardial bridging increases the risk of coronary spasm

BACKGROUND: Myocardial bridging (MB) has been associated with cardiac events. Whether coronary spasm is one factor contributing to those events is unknown. HYPOTHESIS: This study investigated whether the likelihood of coronary spasm is increased in patients with MB. METHODS: A spasm-provocation test was performed by infusing acetylcholine into the left coronary artery in 114 Japanese patients with chest pain. The test result was defined as positive when the diameter of the coronary artery was reduced by > or = 50% and ST-segment changes were documented. Myocardial bridging was defined as a > 15% reduction in coronary arterial diameter during systole after intracoronary injection of nitroglycerin. RESULTS: Myocardial bridging was identified in 41 patients (36%) and was located in the mid-segment of the left anterior descending coronary artery (LAD) in all patients. Patients with MB experienced coronary spasm more frequently than patients without MB (MB+: 73%; MB-: 40%, p = 0.0006). Furthermore, among patients with a positive spasm-provocation test, coronary spasm occurred more frequently in the mid-segment of the LAD in patients with MB than in those without MB (MB+: 73%; MB-: 45%, p = 0.0259). Multivariate regression analysis demonstrated that MB was a predictor of coronary spasm (odds ratio: 3.478, p = 0.0088). CONCLUSIONS: These results suggest that MB increases the risk of coronary spasm and that coronary spasm may be the proximate etiology of cardiac events associated with MB.     

PDE5 inhibitor sildenafil citrate augments endothelium-dependent vasodilation in smokers

Smoking is associated with endothelial dysfunction. The purpose of this study was to determine the effect of sildenafil, an inhibitor of phosphodiesterase type 5 (PDE5), on endothelial function in smokers. We evaluated the forearm blood flow (FBF) responses to acetylcholine (ACh), an endothelium-dependent vasodilator, and to sodium nitroprusside (SNP), an endothelium-independent vasodilator, before and after oral sildenafil administration (100 mg) with a strain-gauge plethysmograph in 10 young healthy male smokers and 10 young healthy male nonsmokers. FBF response to ACh was lower in smokers than in nonsmokers. The vasodilatory effects of SNP were similar in both groups. Sildenafil increased the FBF response to ACh from 9.3+/-2.0 to 12.5+/-3.5 mL/min per 100 mL tissue in smokers and from 12.6+/-5.6 to 19.6+/-8.4 mL/min per 100 mL tissue in nonsmokers, and it increased the response to SNP from 13.3+/-3.9 to 15.1+/-4.3 mL/min per 100 mL tissue in smokers and from 14.8+/-5.2 to 18.4+/-6.0 mL/min/100 mL tissue in nonsmokers (P<0.05 for all). The ratio of maximal ACh-stimulated FBF expressed as a ratio of maximal SNP-stimulated FBF significantly increased after administration of sildenafil in both groups. Infusion of NG-monomethyl-L-arginine, a nitric oxide synthase inhibitor, abolished sildenafil-induced augmentation of the FBF response to ACh in both groups. The findings suggest that endothelial function is impaired in smokers compared with that in nonsmokers, that inhibition of PDE5 by sildenafil significantly increases nitric oxide-mediated vasodilation, and that the activities of PDE5 in smokers and nonsmokers may be similar.     

Telomere length in human liver diseases

Abstract: To determine the role of telomere-mediated gene stability in hepatocarcinogenesis, we examined the telomere length of human liver with or without chronic liver diseases and hepatocellular carcinomas (HCC). The mean telomere restriction fragment (TRF) length of normal liver (n=13), chronic hepatitis (n=11), liver cirrhosis (n=24) and HCC (n=24) was 7.8±0.2, 7.1±0.3, 6.4±0.2 and 5.2±0.2 kb, respectively (mean±standard error). TRF length decreased with a progression of chronic liver diseases and that in HCC was significantly shorter than that in other chronic liver diseases (p<0.05). The ratios of TRF length of HCC to that of corresponding surrounding liver of well differentiated (n=7), moderately differentiated (n=10) and poorly differentiated (n=4) HCCs were 0.83±0.06, 0.75±0.05 and 0.98±0.09, respectively. The ratio of poorly differentiated HCC was significantly higher than that of moderately differentiated HCC (p<0.05). A comparison between the size and telomere length ratio of moderately differentiated HCCs revealed a decrease of the ratio with size until it reached 50 mm in diameter. In contrast, the ratio increased as the size enlarged over 50 mm. These findings suggest that the gene stability of the liver cells mediated by the telomere is reduced as chronic liver disease progresses and that telomerase is activated in poorly differentiated HCC and moderately differentiated HCC over 50 mm in diameter.     

Treatment for Churg-Strauss syndrome: induction of remission and efficacy of intravenous immunoglobulin therapy.

Churg-Strauss syndrome (CSS) is characterized by the presence of asthma, eosinophilia, and small-vessel vasculitis with granuloma. It is a distinct entity, as determined from all classifications of systemic vasculitis. The poor prognostic factors in CSS are renal insufficiency, cardiomyopathy, severe gastrointestinal (GI) tract, and central nervous systems (CNS) involvement. The initial management of CSS should include a high dose of a corticosteroid: prednisone at 1 mg/kg/day or its equivalent for methylprednisolone with tapering over 6 months. In patients with severe or rapidly progressing CSS, the administration of methylprednisolone pulse at 1 g/body/day for 3 days is recommended. When corticosteroid therapy does not induce remission, or when patients have poor prognostic factors, immunosuppressive cytotoxic therapy is indicated. However, some patients with severe CSS often show resistance to conventional treatment. We think that IVIG therapy is a hopeful candidate for second-line treatment for CSS patients, particularly in the case of neuropathy and/or cardiomyopathy, which are resistant to conventional therapy. However, there is not much evidence supporting the effectiveness of IVIG in CSS, and the mechanisms underlying the action of IVIG remain unclear. Now we are performing clinical trials of IVIG therapy for CSS patients who are resistant to conventional treatment, through a nationwide double-blinded placebo-controlled study in Japan.     

Thymidine phosphorylase and angiogenesis in early stage esophageal squamous cell carcinoma

Background

The relationship between thymidine phosphorylase (TP) and angiogenesis at the early stage of esophageal squamous cell carcinoma has been unclear.

Methods

Using 14 samples of normal squamous epithelium, 11 samples of low-grade intraepithelial neoplasia, and 64 samples of superficial esophageal cancer, microvessel density (MVD) was estimated using immunostaining for CD34 and CD105. TP expression was also evaluated in both cancer cells and stromal monocytic cells (SMCs). We then investigated the correlation between MVD and TP expression in both cancer cells and SMCs.

Results

On the basis of the above parameters, MVD was significantly higher in cancerous lesions than in normal squamous epithelium. In terms of CD34 and CD105 expression, MVD showed a gradual increase from normal squamous epithelium, to low-grade intraepithelial neoplasia, and then to M1 and M2 cancer, and M3 or deeper cancer. M1 and M2 cancer showed overexpression of TP in both cancer cells and SMCs. There was no significant correlation between TP expression in cancer cells and MVD estimated from CD34 (rS = 0.16, P = 0.21) or CD105 (rS = 0.05, P = 0.68) expression. Significant correlations were found between TP expression in SMCs and CD34-related (rS = 0.46, P < 0.001) and CD105-related (rS = 0.34, P < 0.01) MVD. In M3 or deeper cancers, there were no significant correlations between TP expression in cancer cells or SMCs and venous invasion, lymphatic invasion, and lymph node metastasis.

Conclusion

TP expression is activated in both cancer cells and stromal monocytic cells at the very early stage of ESCC progression. TP expression in SMCs, rather than in cancer cells, is significantly correlated with angiogenesis.

     

Haptoglobin therapy for acute favism: a Japanese boy with glucose-6-phosphate dehydrogenase Guadalajara

Summary. We report the case of a 2-year-old Japanese boy with acute favism who was treated with human haptoglobin products. He had been exhibiting chronic nonspherocytic haemolytic anaemia until the diagnosis of glucose-6-phosphate dehydrogenase (G6PD) deficiency when 14 months old. He suffered a favic crisis at 24 months of age, when the administration of haptoglobin was effective for relieving bilirubinaemia and haemoglobinuria. Serum-free Hb rapidly decreased to normal levels despite the sustained level of serum lactate dehydrogenase. His G6PD gene was G6, Guadalajara. This is the first application of haptoglobin therapy for acute favism and the first reported case of Japanese G6PD deficiency with typical favic crisis. Haptoglobin treatment might be helpful for managing the haemolytic crisis in the disease.     

Effect of kihito extract granules on cognitive function in patients with Alzheimer's-type dementia

Background:   It has been recently suggested that Japanese herbal (kampo) medicines, such as kami-untan-to, may improve cognitive function in elderly subjects with Alzheimer's disease. Polygalae radix is thought to be a useful component of kami-untan-to because it enhances the activity of choline acetyltransferase in cultured neuronal cells. The purpose of the present study was to investigate the safety and usefulness of kihito extract granules, a commercially available Japanese herbal medicine that contains P. radix , for elderly patients with senile dementia.
Methods:   Seventy-five elderly subjects (84.4 ± 6.4 years) with senile dementia of Alzheimer type according to Diagnostic and Statistical Manual of Mental Disorders , 4th edition criteria were randomly assigned to the non-treatment, goshajinkigan (control kampo medicine) or kihito groups. Each medicine was given three times a day for 3 months.
Results:   There was no severe adverse event in any of the groups. We examined the Mini-Mental State Examination (MMSE), the activities of daily living (ADL) scale and cerebrovascular single photon emission computed tomography (SPECT) before and after treatment. MMSE scores were significantly improved only in the kihito group (+1.65 ± 0.53) but not in the non-treatment (−0.3 ± 0.67) and goshajinkigan (−0.58 ± 0.49) groups. ADL scores remained unchanged in all groups. Treatment with kihito was not associated with an increase in cerebral blood flow.
Conclusion:   These results propose that kihito may be useful and has potential to be tested as a medicine for Alzheimer's-type senile dementia, although further examination is required to clarify the mechanism of the improving effect of kihito on cognitive function.