Translocation of cellular prion protein to non-lipid rafts protects human prion-mediated neuronal damage

Prions are the causative agents of transmissible spongiform encephalopathies, such as variant Creutzfeldt-Jakob disease in humans. Cellular prion proteins (PrPC) connect with cholesterol- and glycosphingolipid-rich lipid rafts through association of their glycosyl-phosphatidylinositol (GPI) anchor with saturated raft lipids and interaction of their N-terminal regions. Our previous study showed that cellular cholesterol enrichment prevented PrP(106-126)-induced neuronal death. We have now studied the influence of membrane cholesterol in PrP(106-126)-mediated neurotoxicity and identified membrane domains involved in this activity. We found that PrPC is normally distributed in lipid rafts, but high membrane cholesterol levels as a result of cholesterol treatment led to the translocation of PrPC from lipid rafts to non-lipid rafts. Moreover, cholesterol-mediated PrPC translocation protects PrP(106-126)-mediated apoptosis and p-38 activation and caspase-3 activation. In a mitochondrial functional assay including mitochondrial transmembrane potential, cholesterol treatment prevented the loss of mitochondrial potential, translocation of Bax and cytochrome c by prion protein fragment. Our results indicate that modulation of the PrPC location appears to protect against neuronal cell death caused by prion peptides. The results of this study suggest that regulation of membrane cholesterol affects the translocation of PrPC, which in turn regulates PrP(106-126)-induced mitochondrial dysfunction and neurotoxicity.     

Lack of association of RAD51 genetic variations with hepatitis B virus clearance and occurrence of hepatocellular carcinoma in a Korean population

The RecA homolog, E. coli (S. cerevisiae) (RAD51) may modulate hepatitis B virus (HBV) infection by maintaining genome integrity and mediating homologous DNA repairs. In this study, 16 sequence variations were detected by resequencing all exons, the exon-intron boundary, and promoter regions of the human RAD51 gene in DNA samples of 24 unrelated individuals. To investigate the association of common variations in the RAD51 locus with HBV infection and hepatocellular carcinoma (HCC) occurrence, six common polymorphisms were genotyped in a total of 1,103 Korean HBV cohort, composed of 433 spontaneously recovered patients as controls and 670 chronic carriers of HBV, who were stratified further into 327 cirrhosis/chronic hepatitis patients and 343 patients with HCC infected with HBV. Logistic analyses revealed no significant association of RAD51 polymorphisms and haplotypes with HBV clearance and HCC occurrence (P > 0.05). Furthermore, with age of infection as an important factor in disease progression to HCC, results from the Cox proportional hazards analysis showed no significant associations between any of the tested RAD51 variants and the age of onset of HCC (P > 0.05), suggesting that genetic polymorphisms of RAD51 may not play an important role in clearance of HBV and disease progression to HCC. Although studies in other populations are needed to confirm these findings, this preliminary data may contribute to the current knowledge on the pathogenesis of hepatitis.     

Durability of a sustained virological response in chronic hepatitis C patients treated with pegylated interferon alfa and ribavirin

Background/Aims

The reappearance rates of hepatitis C virus (HCV) RNA after a sustained virological response (SVR) have been reported to be 1-2%. We investigated the reappearance rate of HCV RNA after SVR in chronic hepatitis C (CHC) patients treated with pegylated interferon (PEG-IFN) and ribavirin.

Methods

In total, 292 CHC patients who achieved an SVR after PEG-IFN and ribavirin treatment were included. They were treated with subcutaneous injections of either PEG-IFN-α 2a or 2b plus ribavirin orally. Liver function tests and qualitative HCV RNA assays were performed every 6 months during the follow-up period after an SVR.

Results

Among the 292 patients, 224 (genotype 1, 92; genotype non-1, 132) were followed up for more than 6 months after SVR. These 224 patients were aged 48.1±11.5 years (mean±SD), and 129 of them were male. The median follow-up duration was 18 months (range 6-60 months). The reappearance rate of HCV RNA during follow-up was 0%. Two patients who achieved an SVR developed hepatocellular carcinoma during the follow-up period.

Conclusions

An SVR was maintained in all CHC patients treated with PEG-IFN plus ribavirin during a median follow-up of 18 months. However, a screening test for hepatocellular carcinoma is needed for patients with an SVR.     

Effects of sFlt-1 and alpha 2-macroglobulin on vascular endothelial growth factor-induced endothelin-1 upregulation in human microvascular endothelial cells

Introduction

Soluble fms-like tyrosine kinase-1 (sFlt-1) is a vascular endothelial growth factor (VEGF) binding protein and potent antagonist of VEGF. Alpha 2 macroglobulin (α₂M) is another major binding protein for circulating VEGF, which is present in human plasma at higher concentration (2–4 mg/mL) than sFlt-1. This study investigated the effects of sFlt-1 and α₂M on VEGF-induced endothelin-1 (ET-1) upregulation in human microvascular endothelial cell-1 (HMEC-1).

Methods

HMEC-1 was cultured and incubated with varying concentrations of sFlt-1 and α₂M in combination with VEGF. ET-1 mRNA expression in the cells was measured by real time RT-PCR and ET-1 protein by western blot analysis.

Results

ET-1 expression in HMEC-1 incubated with VEGF significantly increased in time- and dose-dependent manners. Next, HMEC-1 was treated with the sFlt-1 (10–1000 ng/mL) or α₂M (10–10000 ng/mL) in the presence of VEGF (10 ng/mL). We found that sFlt-1 induced a significant decrease of ET-1 expression upregulated by VEGF, while α₂M did not affect the VEGF-induced ET-1 expression.

Conclusions

sFLT-1 suppressed the VEGF-induced the ET-1 expression of HMEC-1. However, α₂M did not show a significant effect on the ET-1 expression that was induced by VEGF. The results suggest that a certain proportion of the bound form α₂M-VEGF have a biological action involved in the pathophysiology of preeclampsia.     

Magnetic resonance evaluation of fibrovascular ingrowth into porous polyethylene orbital implant

We assessed the fibrovascular ingrowth into porous orbital implant with MRI. Twelve cases underwent T1WI, T2WI, Gd-enhanced T1WI, and Short Tau Inversion Recovery (STIR) images. Gd-enhanced T1WI showed homogeneous enhancement (n=4), peripheral and posterior part enhancement (n=7), and anterior part enhancement (n=1) of implants. High signal intensity portions on STIR images coincided with the enhancing portions on Gd-enhanced T1WI. Gd-enhanced T1WI is an excellent method for assessment of fibrovascular ingrowth into orbital implant and STIR images may be a comparable method to Gd-enhanced T1WI.     

Enhanced ridge preservation by bone mineral bound with collagen-binding synthetic oligopeptide: a clinical and histologic study in humans

Background: The ridge‐preservation technique has been applied with membrane alone or membrane plus graft. Synthetic peptides, mimicking bioactive growth factor or extracellular matrix protein, have been attempted to provide an active surface of the biomaterials in inducing bone formation while alleviating the limitations of whole protein such as short half‐life, immunologic responses. The aim of the present clinical study is to examine the osteogenic effect of synthetic oligopeptide–coated bone mineral compared to bone graft without peptide when applied with collagen membrane in a ridge‐preservation technique. Methods: Synthetic oligopeptide from the collagen‐binding domain of osteopontin was chemically synthesized and coated onto the surface of bone mineral particulates. Ridge preservations were performed at 44 extraction sites in 42 patients (20 males and 22 females). Analyses of clinical parameters and histomorphometric evaluations were conducted to compare the osteogenic effects of the grafts between baseline and 6 months. Results: In the bone grafts of the control group treated without synthetic peptide, new bone formation was only seen around borders and basal areas. However, new bone was observed broadly in the defects of the test group treated with synthetic peptide–coated bone mineral, as seen not only at peripheries but also in the central and coronal parts of bone cores in the defects. The average percentage of new bone formation was significantly higher in the test group (5.3% ± 8.3% versus 10.4% ± 4.6%). The contact percentages between the graft particles and the new bone were 8.2% ± 11.3% for the control group and 20.4% ± 7.5% for the test group (P <0.05). Conclusions: The ridge‐preservation approach using synthetic oligopeptide–coated bone mineral with collagen membrane effectively prevented the resorption of hard tissue with higher bone‐to‐graft contact, and the oligopeptide‐coated bone may be a choice for ridge‐preservation procedures while assuring new bone formation.     

Charlson Co‐morbidity Index and albumin significantly associated with fracture risk in peritoneal dialysis patients

Published literature on fracture in dialysis patients seldom addressed the effect of co‐morbidity and malnutrition. In this study, we reported the incidence and risk factors for fracture in peritoneal dialysis patients. Peritoneal dialysis patients who had fractures between 2006 and 2011 were recruited. Demographic data, details of fracture, Charlson Co‐morbidity Index (CCI) and biochemical parameters were also collected. Non‐fracture controls, matched for age, gender and duration of dialysis, were also recruited at ratio 1:1 for fracture risk analysis. The incidence of fracture was 1 in 37 patient‐years. The commonest site of fracture was neck of femur (n = 16, 55.2%). Twenty‐four patients (82.8%) developed fracture after slip and fall injury. Eight out of 17 self‐ambulatory patients (47.1%) became non‐ambulatory after fracture. Infection was the commonest complication during hospitalization. Univariant analysis demonstrated high CCI (P = 0.001), hypoalbuminaemia (P < 0.001), loss of self autonomy (P = 0.006) and non‐ambulatory state (P = 0.011) significantly associated with increased fracture risk. However, only CCI (odds ratio (OR) 1.373, P = 0.028) and albumin (OR 0.893, P = 0.025) increased fracture risk significantly on multivariant analysis. Bone profile and parathyroid hormone were not significant risk factors. To conclude, fracture associated with adverse outcome in peritoneal dialysis patients. High CCI score and hypoalbuminaemia significantly increase risk of fracture.     

Non‐invasive assessment of kidney allograft fibrosis with shear wave elastography: A radiological‐pathological correlation analysis

Objectives

To evaluate the use of shear wave elastography in assessment of kidney allograft tubulointerstitial fibrosis.

Methods

Shear wave elastography assessment was carried out by two independent operators in kidney transplant recipients who underwent allograft biopsy for clinical indications (i.e. rising creatinine >15% or proteinuria >1 g/day). Allograft biopsies were interpreted by the same pathologist according to the 2013 Banff Classification.

Results

A total of 40 elastography scans were carried out (median creatinine 172.5 μmol/L [interquartile range 133.8–281.8 μmol/L]). Median tissue stiffness at the cortex (22.6 kPa [interquartile range 18.8–25.7 kPa] vs 22.3 kPa [interquartile range 19.0–26.5 kPa], P = 0.70) and medulla (15.0 kPa [interquartile range 13.7–18.0 kPa] vs 15.6 kPa [interquartile range 14.4–18.2 kPa]) showed no significant differences between the two observers. Interobserver agreement was satisfactory (intraclass correlation coefficient of the cortex 0.84, 95% CI 0.70–0.92 and intraclass correlation coefficient of the medulla 0.88, 95% CI 0.78–0.94). The areas under the receiver operating characteristic curves for detection of tubulointerstitial fibrosis were estimated to be 0.75 (95% CI 0.61–0.89), 0.85 (95% CI 0.75–0.95) and 0.65 (95% CI 0.53–0.78) for cortical, medullary tissue stiffness and serum creatinine, respectively.

Conclusions

Shear wave elastography can be used as a non‐invasive tool to evaluate kidney allograft fibrosis with reasonable interobserver agreement and superior test performance to serum creatinine in detecting early tubulointerstitial fibrosis.     

Outcome of conventional treatment and prognostic factor in elderly glioblastoma patients

Background

Glioblastoma (GBM) is the most life-threatening primary brain tumour. Especially in elderly patients, a poorer outcome is noticeable. Until now, the effectiveness of the conventional active treatment has been controversial. The purpose of this study is to find the optimal treatment for elderly patients with newly diagnosed GBM.

Method

The authors retrospectively reviewed 301 patients who were diagnosed with GBM at a single centre from January 2006 to December 2010. All patients were divided into younger and elderly groups based on the cut-off age of 65 years, and the treatment outcome was analysed.

Results

Of 301 patients, 67 (23.3 %) patients were 65 years old or older, and 234 (77.7 %) patients were younger than 65 years. In the elderly group, 49 patients received surgical resection and 18 patients received biopsy. Forty-seven patients (70.1 %) underwent concomitant chemoradiotherapy (CCRT) and 38 patients (56.7 %) underwent adjuvant temozolomide (TMZ) chemotherapy. The median overall survival (OS) of elderly patients was 12.0 months and the progression-free survival (PFS) was 8.5 months. The median OS of elderly patients who underwent CCRT and adjuvant TMZ chemotherapy increased to 16.2 months. On the multivariate analysis, tumour infiltration (p?=?0.005), and resection (p?=?0.001) were significant independent prognostic factors in elderly patients. The grade 3 or 4 complication rate was not statistically different between the younger group (n?=?22, 9.4 %) and the elderly group (n?=?8, 12 %).

Conclusion

Elderly patients diagnosed with GBM had a survival benefit and a low complication rate with the conventional treatment. Therefore, elderly patients should be encouraged to receive the conventional active treatment.     

Ionotropic glutamate receptor GluA4 and T‐type calcium channel Cav3.1 subunits control key aspects of synaptic transmission at the mouse L5B‐POm giant synapse

The properties and molecular determinants of synaptic transmission at giant synapses connecting layer 5B (L5B) neurons of the somatosensory cortex (S1) with relay neurons of the posteriomedial nucleus (POm) of the thalamus have not been investigated in mice. We addressed this by using direct electrical stimulation of fluorescently labelled single corticothalamic terminals combined with molecular perturbations and whole‐cell recordings from POm relay neurons. Consistent with their function as drivers, we found large‐amplitude excitatory postsynaptic currents (EPSCs) and multiple postsynaptic action potentials triggered by a single presynaptic action potential. To study the molecular basis of these two features, ionotropic glutamate receptors and low voltage‐gated T‐type calcium channels were probed by virus‐mediated genetic perturbation. Loss of GluA4 almost abolished the EPSC amplitude, strongly delaying the onset of action potential generation, but maintaining the number of action potentials generated per presynaptic action potential. In contrast, knockdown of the Ca_v3.1 subunit abrogated the driver function of the synapse at a typical resting membrane potential of ?70 mV. However, when depolarizing the membrane potential to ?60 mV, the synapse relayed single action potentials. Hence, GluA4 subunits are required to produce an EPSC sufficiently large to trigger postsynaptic action potentials within a defined time window after the presynaptic action potential, while Ca_v3.1 expression is essential to establish the driver function of L5B‐POm synapses at hyperpolarized membrane potentials.