Aggregation-prone c9FTD/ALS poly(GA) RAN-translated proteins cause neurotoxicity by inducing ER stress

The occurrence of repeat-associated non-ATG (RAN) translation, an atypical form of translation of expanded repeats that results in the synthesis of homopolymeric expansion proteins, is becoming more widely appreciated among microsatellite expansion disorders. Such disorders include amyotrophic lateral sclerosis and frontotemporal dementia caused by a hexanucleotide repeat expansion in the C9ORF72 gene (c9FTD/ALS). We and others have recently shown that this bidirectionally transcribed repeat is RAN translated, and the “c9RAN proteins” thusly produced form neuronal inclusions throughout the central nervous system of c9FTD/ALS patients. Nonetheless, the potential contribution of c9RAN proteins to disease pathogenesis remains poorly understood. In the present study, we demonstrate that poly(GA) c9RAN proteins are neurotoxic and may be implicated in the neurodegenerative processes of c9FTD/ALS. Specifically, we show that expression of poly(GA) proteins in cultured cells and primary neurons leads to the formation of soluble and insoluble high molecular weight species, as well as inclusions composed of filaments similar to those observed in c9FTD/ALS brain tissues. The expression of poly(GA) proteins is accompanied by caspase-3 activation, impaired neurite outgrowth, inhibition of proteasome activity, and evidence of endoplasmic reticulum (ER) stress. Of importance, ER stress inhibitors, salubrinal and TUDCA, provide protection against poly(GA)-induced toxicity. Taken together, our data provide compelling evidence towards establishing RAN translation as a pathogenic mechanism of c9FTD/ALS, and suggest that targeting the ER using small molecules may be a promising therapeutic approach for these devastating diseases.     

Prevalence and predictors of abnormal arterial function in statin-treated type 2 diabetes mellitus patients

Arterial dysfunction (AD) in type 2 diabetes mellitus (T2DM) predicts cardiovascular events. The objective was to investigate the prevalence and predictors of AD in statin-treated T2DM patients. We measured flow-mediated (FMD) and nitrate-mediated (NMD) brachial artery dilatation in 86 statin-treated T2DM patients. Patients were classified into 2 groups: normal arterial function (FMD ≥3.7% with NMD ≥11.9%) or AD (FMD <3.7% with or without NMD <11.9%). Endothelial dysfunction without smooth muscle cell dysfunction (ED) was defined as FMD less than 3.7% with NMD of at least 11.9%, and endothelial dysfunction with smooth muscle cell dysfunction (ED/SMD) was defined as FMD less than 3.7% with NMD less than 11.9%. Predictors of arterial function were investigated using linear and logistic regression methods. The prevalence of AD was 33.7% (23.2% with ED and 10.5% with ED/SMD). In multivariate linear regression, history of hypertension (P < .01), statin dose (P < .05), and estimated glomerular filtration rate (eGFR) (P = .02) were significant predictors of FMD. Sex (P < .01) and creatinine (P = .03) or eGFR (P = .02) predicted NMD. In multivariate logistic regression, the independent predictors of AD were history of hypertension (odds ratio [OR], 8.79; 95% confidence interval, 2.14-36.12; P < .01), age (OR, 1.08; 1.01-1.17; P = .03), and statin dose (OR, 0.33; 0.12-0.87; P = .02). A history of hypertension (OR, 8.99; 1.87-43.26; P < .01) was the sole independent predictor of ED; eGFR (OR, 0.01; 0.00-0.26; P < .01) independently predicted ED/SMD. Our data suggest that one third of statin-treated diabetic patients have residual AD, mainly due to ED alone. Earlier identification and treatment of hypertension and renal impairment may improve AD and further decrease cardiovascular risk in such patients.     

Identification of new CRF51_01B in Singapore using full genome analysis of three HIV type 1 isolates

A recent HIV-1 molecular epidemiology survey in Singapore identified a novel CRF01_AE/B recombinant form, which accounted for 13 (11.9%) of 109 patient samples. Peripheral blood mononuclear cell DNA from three of these 13 patients was used to generate near full-length sequences to characterize the novel CRF01_AE/B recombinant form. The three isolates had a recombinant structure composed of CRF01_AE and subtype B, and shared identical breakpoints. As the three patients were not epidemiologically linked, this recombinant form has been designated CRF51_01B. Identification of the novel recombinant forms indicates ongoing active HIV-1 transmission in Singapore.     

Major complications related to epidural analgesia in children: a 15-year audit of 3,152 epidurals

Background

Complications associated with epidural analgesia in children have a reported incidence of 40-90 in 10,000 epidurals. We sought to determine the incidence of major complications with the use of continuous epidural analgesia that occurred in our centre over the past 15 years and to describe the nature of these complications.

Methods

The Acute Pain Service database at a tertiary care academic pediatric hospital was reviewed retrospectively over a 15-year period. Data were categorized according to patient age (neonate, infant, child one through eight years, and child > eight years), mode of insertion of the epidural (caudal, transsacral, lumbar, thoracic), complication type, and complication severity.

Results

Over the 15-year period, 3,152 epidurals were performed. The use of caudal-thoracic epidurals in neonates and infants has increased since 2007. Twenty-four major complications were identified (incidence, 7.6 in 1,000 epidurals). The rate of complications in neonates was 4.2% compared with 1.4% in infants, 0.5% in children aged one through eight years, and 0.8% in children over eight years of age. The two most common complications were local skin infection and drug error.

Conclusions

Our incidence of major complications and our finding that complications were more common in neonates and infants are both consistent with previously published data. The two most common types of complications are potentially preventable.     

Mismatch Repair Deficiency Screening via Immunohistochemical Staining in Young Asians with Colorectal Cancers

Background

The incidence of mismatch repair deficiency in colorectal cancer (CRC) in young people remains unknown in Asians. The present study assessed the clinicopathological features and efficacy of immunohistochemistry screening for Lynch syndrome in young Asian CRC patients.

Material and methods

This was a retrospective review conducted in Singapore General Hospital between January 2006 and December 2010 of 240 unrelated patients under the age of 50. All patients had immunohistochemical (IHC) staining for mismatch repair proteins in resected CRC specimen data retrieved from a prospective computerized database.

Results

A total of 21 % (n = 51) of the patients had abnormal IHC staining. Loss of staining for MLH1, MSH2, MSH6, and PMS2 proteins was observed in 10, 4, 6, and 13 % of tumors, respectively. Of the 22 patients who had abnormal staining of MLH1, 13 had concomitant abnormal staining for PMS2. One tumor specimen had abnormal staining in all four proteins. If the Amsterdam criteria alone were to be used, 86 % (n = 44) of the cohort would have not been detected for mismatch repair gene defects.

Conclusions

The overall burden of germline mismatch repair deficiency in the Singapore population may be as high as 21 %. The Amsterdam criteria alone are inadequate to detect Lynch syndrome patients. The use of IHC staining of at least four mismatch repair proteins is a useful screening strategy for Lynch syndrome diagnosis. Routine screening of mismatch repair deficiency may be recommended for all young Asian CRC patients.     

Adjuvant Hepatic Intra-arterial Iodine-131-Lipiodol Following Curative Resection of Hepatocellular Carcinoma: A Prospective Randomized Trial

Background

The purpose of the present study was to determine whether intrahepatic injection of ¹³¹I-lipiodol (Lipiodol) is effective against recurrence of surgically resected hepatocellular carcinoma (HCC).

Methods

From June 2001 through March 2007, this nationwide multi-center prospective randomized controlled trial enrolled 103 patients 4–6 weeks after curative resection of HCC with complete recovery (52: Lipiodol, 51: Control). Follow-up was every 3 months for 1 year, then every 6 months. Primary and secondary endpoints were recurrence-free survival (RFS) and overall survival (OS), respectively, both of which were evaluated by the Kaplan–Meier technique and summarized by the hazard ratio (HR). The design was based on information obtained from a similar trial that had been conducted in Hong Kong.

Results

The Lipiodol group showed a small, and nonsignificant, improvement over control in RFS (HR = 0.75; 95 % confidence interval [95 % CI] 0.46–1.23; p = 0.25) and OS (HR = 0.88; 95 % CI 0.51–1.51; p = 0.64). Only two serious adverse events were reported, both with hypothyroidism caused by ¹³¹I-lipiodol and hepatic artery dissection during angiography.

Conclusions

The randomized trial provides insufficient evidence to recommend the routine use of ¹³¹I-lipiodol in these patients.     

SOX17 is expressed in regenerating oligodendrocytes in experimental models of demyelination and in multiple sclerosis

We have previously demonstrated that Sox17 expression is prominent at developmental stages corresponding to oligodendrocyte progenitor cell (OPC) cycle exit and onset of differentiation, and that Sox17 promotes initiation of OPC differentiation. In this study, we examined Sox17 expression and regulation under pathological conditions, particularly in two animal models of demyelination/remyelination and in post‐mortem multiple sclerosis (MS) brain lesions. We found that the number of Sox17 expressing cells was significantly increased in lysolecithin (LPC)‐induced lesions of the mouse spinal cord between 7 and 30 days post‐injection, as compared with controls. Sox17 immunoreactivity was predominantly detected in Olig2⁺ and CC1⁺ oligodendrocytes and rarely in NG2⁺ OPCs. The highest density of Sox17⁺ oligodendrocytes was observed at 2 weeks after LPC injection, coinciding with OPC differentiation. Consistent with these findings, in cuprizone‐treated mice, Sox17 expression was highest in newly generated and in maturing CC1⁺ oligodendrocytes, but low in NG2⁺ OPCs during the demyelination and remyelination phases. In MS tissue, Sox17 was primarily detected in actively demyelinating lesions and periplaque white matter. Sox17 immunoreactivity was co‐localized with NOGO‐A+ post‐mitotic oligodendrocytes both in active MS lesions and periplaque white matter. Taken together, our data: (i) demonstrate that Sox17 expression is highest in newly generated oligodendrocytes under pathological conditions and could be used as a marker of oligodendrocyte regeneration, and (ii) are suggestive of Sox17 playing a critical role in oligodendrocyte differentiation and lesion repair. GLIA 2013;61:1659–1672