Genotype-phenotype correlation in the long-QT syndrome: gene-specific triggers for life-threatening arrhythmias

BACKGROUND

The congenital long-QT syndrome (LQTS) is caused by mutations on several genes, all of which encode cardiac ion channels. The progressive understanding of the electrophysiological consequences of these mutations opens unforeseen possibilities for genotype-phenotype correlation studies. Preliminary observations suggested that the conditions ("triggers") associated with cardiac events may in large part be gene specific.

METHODS AND RESULTS

We identified 670 LQTS patients of known genotype (LQT1, n=371; LQT2, n=234; LQT3, n=65) who had symptoms (syncope, cardiac arrest, sudden death) and examined whether 3 specific triggers (exercise, emotion, and sleep/rest without arousal) differed according to genotype. LQT1 patients experienced the majority of their events (62%) during exercise, and only 3% occurred during rest/sleep. These percentages were almost reversed among LQT2 and LQT3 patients, who were less likely to have events during exercise (13%) and more likely to have events during rest/sleep (29% and 39%). Lethal and nonlethal events followed the same pattern. Corrected QT interval did not differ among LQT1, LQT2, and LQT3 patients (498, 497, and 506 ms, respectively). The percent of patients who were free of recurrence with ss-blocker therapy was higher and the death rate was lower among LQT1 patients (81% and 4%, respectively) than among LQT2 (59% and 4%, respectively) and LQT3 (50% and 17%, respectively) patients.

CONCLUSIONS

Life-threatening arrhythmias in LQTS patients tend to occur under specific circumstances in a gene-specific manner. These data allow new insights into the mechanisms that relate the electrophysiological consequences of mutations on specific genes to clinical manifestations and offer the possibility of complementing traditional therapy with gene-specific approaches.

OP-1 cDNA encodes an osteogenic protein in the TGF-beta family

Amino acid sequences of two tryptic peptides derived from enriched bovine osteogenic protein preparations revealed considerable homology to two members of the TGF-beta (transforming growth factor beta) supergene family, DPP (decapentaplegic protein) of Drosophila and Vg-1 (vegetal protein) of Xenopus. Building upon this information we constructed a synthetic consensus gene to use as a probe to screen human genomic libraries. This resulted in the isolation of three interrelated genes. Among these were BMP-2b and BMP-3 which have recently been described by others. The third gene, termed OP-1 (osteogenic protein one), is new and was subsequently shown to encode the human homolog of a major component of bovine osteogenic protein. The genomic clones were used to isolate the corresponding complementary DNA (cDNA) clones. Sequence analysis indicates that OP-1 is a relative of the murine Vgr-1 (Vg-1 related gene). This report describes the cDNA structure and putative amino acid sequence of OP-1.

Systematic review: pentoxifylline for the treatment of severe alcoholic hepatitis

BACKGROUND

Acute alcoholic hepatitis (AH) is a severe manifestation of alcoholic liver disease with a grave prognosis. Pentoxifylline, an oral antitumour necrosis factor agent, has been reported to reduce mortality and incidence of hepatorenal syndrome (HRS) in severe alcoholic hepatitis (SAH).

AIM

To summarise evidence for the use of pentoxifylline in SAH.

METHODS

A literature search was undertaken using MeSH terms 'hepatitis, alcoholic' and 'pentoxifylline' using the set operator AND. We included randomised controlled trials examining pentoxifylline in SAH, published as abstracts or full manuscripts. Risk ratios (RRs) were calculated for pooled data using random effects modelling. Risk of bias was assessed using Cochrane group criteria and quality of trials assessed using 'Consolidated Standards of Reporting Trials' CONSORT guidelines.

RESULTS

Ten trials including 884 participants were included, from six papers and four abstracts. There was significant heterogeneity between trials regarding control groups and trial end-points. Treatment was given for 28 days in all trials except one. Pooling of data showed a reduced incidence of fatal HRS with pentoxifylline compared with placebo (RR: 0.47, 0.26-0.86, P = 0.01), but no survival benefit at 1 month (RR: 0.58, 0.31-1.07, P = 0.06). There were no significant differences between treatment groups in trials of pentoxifylline vs. corticosteroid, or vs. combination therapy.

CONCLUSIONS

Pentoxifylline appears superior to placebo in prevention of fatal HRS and thus may be effective treatment of SAH when corticosteroids are contraindicated. However, multiple trials have failed to show conclusive superiority of either pentoxifylline or corticosteroids.

Road traffic offending, stress, age, and accident history among male and female drivers

This paper draws on data gathered during a larger study of driving behaviour to explore possible connections between stress, offending against the traffic laws, and accident rates, and gives particular attention to comparisons between male and female drivers. Data were gathered from 422 drivers by a postal questionnaire, and further measures of stress were obtained during semi-structured interviews with a specially selected subset of 66 of them. Analyses of variance investigated links between offending rates, accident history, and up to seven measures of stress, taking age and gender into account. In the results accident history, although positively related to offending, played little part in links involving stress variables. The principal findings were that (a) stress, both on and off the road, was positively associated with offending among both male and female drivers, and (b) although females overall offended less than males, females experienced more stress than males whatever their level of offending. One possible interpretation of these results is suggested by the feminist literature, which could account for both the higher levels of stress and lower levels of offending found among women drivers. However, there is unlikely to be a clear-cut gender divide in offending-stress relationships, and some small groups of female drivers in the study behaved like male ones. It is suggested that people's driving reflects their lifestyles, and that women drivers' patterns of offending and stress will resemble those of male drivers to the extent that their lives and concerns are similar to men's. It is concluded that this position warrants further research.

An unusual bovine pancreatic protein exhibiting pH-dependent globule-fibril transformation and unique amino acid sequence

An unusual hitherto unreported protein, extracted in acid from fresh bovine pancreas, has been purified and characterized biochemically. It precipitates in the neutral pH range in the form of uniform double-helical threads, each strand of which is smooth and of uniform diameter, about 7-8 nm. The threads dissolve to a nonviscous solution below pH 3.6 and above pH 9.4, and they reconstitute reversibly in the pH range in between. The monomer in acid has an apparent molecular weight of 17,800 and consists of two disulfide-linked nonidentical polypeptide chains of different lengths. It is rich in aromatic amino acids, particularly tryptophan. There is no significant content of carbohydrate, fatty acid, or bound phosphate. The amino acid sequences of the first NH2-terminal 48 residues of the A chain and 35 residues of the B chain appear to be unique, differing from all other reported animal proteins, including those of the pancreas. Thus far, a function has not been found.

Simeprevir in combination with sofosbuvir in treatment-naïve and -experienced patients with hepatitis C virus genotype 4 infection: a Phase III, open-label, single-arm study (PLUTO)

BACKGROUND

Hepatitis C virus (HCV) infection is a leading cause of liver cirrhosis and subsequent hepatocellular carcinoma. HCV genotype 4 is found widely in the Middle East, Egypt and Africa, and has also spread into Europe. There are limited data available regarding the use of direct-acting antiviral agents in HCV genotype 4-infected patients with cirrhosis.

AIM

To evaluate in the phase III, open-label, single-arm PLUTO study the efficacy and safety of 12 weeks of simeprevir (HCV NS3/4A protease inhibitor) plus sofosbuvir (HCV nucleotide-analogue NS5B polymerase inhibitor) in treatment-naïve and (peg)interferon ± ribavirin-experienced HCV genotype 4-infected patients, with or without compensated cirrhosis.

METHODS

Adult patients with chronic HCV genotype 4 infection received simeprevir 150 mg once-daily and sofosbuvir 400 mg once-daily for 12 weeks. The primary efficacy endpoint was sustained virologic response 12 weeks after the end of treatment (SVR12). Safety was also assessed.

RESULTS

Forty patients received treatment; the majority were male (73%) and treatment-experienced (68%). Overall, 7/40 (18%) patients had compensated cirrhosis. All patients achieved SVR12 [100% (Clopper-Pearson 95% confidence interval: 91-100%)]. Adverse events, all Grade 1 or 2, were reported in 20/40 (50%) patients. No serious adverse events were reported and no patients discontinued study treatment. Grade 3 treatment-emergent laboratory abnormalities were noted in 2/40 (5%) patients.

CONCLUSIONS

Treatment with simeprevir plus sofosbuvir for 12 weeks resulted in SVR12 rates of 100% in treatment-naïve and -experienced patients with HCV genotype 4 infection with or without compensated cirrhosis, and was well tolerated. [NCT02250807].

Operator training requirements and diagnostic accuracy of Fibroscan in routine clinical practice

BACKGROUND

Fibroscan is a quick, non-invasive technique used to measure liver stiffness (kPa), which correlates with fibrosis. To achieve a valid liver stiffness evaluation (LSE) the operator must obtain all the following three criteria: (1) ≥10 successful liver stiffness measurements; (2) IQR/median ratio <0.30 and (3) ≥60% measurement success rate.

OBJECTIVES

To assess the operator training requirements and the importance of adhering to the LSE validity criteria in routine clinical practice.

METHODS

We retrospectively analysed the LSE validity rates of 2311 Fibroscans performed (1 August 2008 to 31 July 2011) in our tertiary liver outpatients department at the University Hospital Birmingham, UK. The diagnostic accuracy of Fibroscan was assessed in 153 patients, by comparing LSE (valid and invalid) with the modified Ishak fibrosis stage on liver biopsy.

RESULTS

Learning curve analysis highlighted that the greatest improvement in validity of LSE rates occurs in the operator's first 10 Fibroscans, reaching 64.7% validity by the 50th Fibroscan. The correlation between LSE and the fibrosis stage on liver biopsy was superior in patients with a valid LSE (n=97) compared with those with an invalid LSE (n=56) (rs 0.577 vs 0.259; p=0.022). Area under receiving operating characteristics for significant fibrosis was greater when LSE was valid (0.83 vs 0.66; p=0.048). Using an LSE cut-off of 8 kPa, the negative predictive value of valid LSE was superior to invalid LSE for the detection of significant (84% vs 71%) and advanced fibrosis (100% vs 93%).

CONCLUSIONS

Fibroscan requires minimal operator training (≥10 observed on patients), and when a valid LSE is obtained, it is an accurate tool for excluding advanced liver fibrosis. To ensure the diagnostic accuracy of Fibroscan it is essential that the recommended LSE validity criteria are adhered to in routine clinical practice.

REpeated AutoLogous Infusions of STem cells In Cirrhosis (REALISTIC): a multicentre, phase II, open-label, randomised controlled trial of repeated autologous infusions of granulocyte colony-stimulating factor (GCSF) mobilised CD133+ bone marrow stem cells in patients with cirrhosis. A study protocol for a randomised controlled trial

INTRODUCTION

Liver disease mortality and morbidity are rapidly rising and liver transplantation is limited by organ availability. Small scale human studies have shown that stem cell therapy is safe and feasible and has suggested clinical benefit. No published studies have yet examined the effect of stem cell therapy in a randomised controlled trial and evaluated the effect of repeated therapy.

METHODS AND ANALYSIS

Patients with liver cirrhosis will be randomised to one of three trial groups: group 1: Control group, Standard conservative management; group 2 treatment: granulocyte colony-stimulating factor (G-CSF; lenograstim) 15 µg/kg body weight daily on days 1-5; group 3 treatment: G-CSF 15 µg/kg body weight daily on days 1-5 followed by leukapheresis, isolation and aliquoting of CD133+ cells. Patients will receive an infusion of freshly isolated CD133+ cells immediately and frozen doses at days 30 and 60 via peripheral vein (0.2×10(6) cells/kg for each of the three doses). Primary objective is to demonstrate an improvement in the severity of liver disease over 3 months using either G-CSF alone or G-CSF followed by repeated infusions of haematopoietic stem cells compared with standard conservative management. The trial is powered to answer two hypotheses of each treatment compared to control but not powered to detect smaller expected differences between the two treatment groups. As such, the overall α=0.05 for the trial is split equally between the two hypotheses. Conventionally, to detect a relevant standardised effect size of 0.8 point reduction in Model for End-stage Liver Disease score using two-sided α=0.05(overall α=0.1 split equally between the two hypotheses) and 80% power requires 27 participants to be randomised per group (81 participants in total).

ETHICS AND DISSEMINATION

The trial is registered at Current Controlled Trials on 18 November 2009 (ISRCTN number 91288089, EuDRACT number 2009-010335-41). The findings of this trial will be disseminated to patients and through peer-reviewed publications and international presentations.

Covalent structure of collagen: amino acid sequence of alpha1-CB6A of chick skin collagen

The amino acid sequence of chick skin collagen alpha1-CB6A, a peptide containing 107 residues obtained from the helical region near the carboxy-terminus of the alpha1(I) chain by cyanogen bromide cleavage, has been determined. This was accomplished by automated Edman degradation of the hydroxylamine-produced fragments and of the tryptic peptides prepared with and without prior maleylation. The data show that this portion of the alpha1(I) chain from chick skin is identical in 90 percent of the residues to the corresponding peptide region of calf skin collagen reported previously.

The amino acid sequence of chick skin collagen alpha1-CB7

The amino acid sequence of chick skin collagen alpha1-CB7, the 268 CNBr peptide from the helical portion of the alpha1 chain, has been determined by automatic and manual degradation of tryptic and chymotryptic peptides, and of the COOH-terminal fragment produced by cleavage with animal collagenase. The resulting sequence shows 94% identity with that of the corresponding peptide from calf skin collage (Fietzek, P. P., Rexrodt, F. W., Hopper, K. E., and Kühn, K. (1973), Eur. J. Biochem. 38, 396). The bond cleaved by animal collagenase has been identified as Gly-Ile at residues 221-222 of alpha1-CB7.

Angiotensin II, Hypercholesterolemia, and Vascular Smooth Muscle Cells: A Perfect Trio for Vascular Pathology

Cardiovascular disease is the leading cause of morbidity and mortality in the Western and developing world, and the incidence of cardiovascular disease is increasing with the longer lifespan afforded by our modern lifestyle. Vascular diseases including coronary heart disease, high blood pressure, and stroke comprise the majority of cardiovascular diseases, and therefore represent a significant medical and socioeconomic burden on our society. It may not be surprising that these conditions overlap and potentiate each other when we consider the many cellular and molecular similarities between them. These intersecting points are manifested in clinical studies in which lipid lowering therapies reduce blood pressure, and anti-hypertensive medications reduce atherosclerotic plaque. At the molecular level, the vascular smooth muscle cell (VSMC) is the target, integrator, and effector cell of both atherogenic and the major effector protein of the hypertensive signal Angiotensin II (Ang II). Together, these signals can potentiate each other and prime the artery and exacerbate hypertension and atherosclerosis. Therefore, VSMCs are the fulcrum in progression of these diseases and, therefore, understanding the effects of atherogenic stimuli and Ang II on the VSMC is key to understanding and treating atherosclerosis and hypertension. In this review, we will examine studies in which hypertension and atherosclerosis intersect on the VSMC, and illustrate common pathways between these two diseases and vascular aging.

Paul AK, Autieri MV, Scalia R, Rizzo V, Hashimoto T, Eguchi S. Glucose consumption of vascular cell types in culture: toward optimization of experimental conditions

In this study, we have looked for an optimum media glucose concentration and compared glucose consumption in three vascular cell types, endothelial cells (ECs), vascular smooth muscle cells (VSMCs), and adventitial fibroblasts (AFs) with or without angiotensin II (AngII) stimulation. In a subconfluent 6-well experiment in 1 mL DMEM with a standard low (100 mg/dL), a standard high (450 mg/dL), or a mixed middle (275 mg/dL) glucose concentration, steady and significant glucose consumption was observed in all cell types. After 48-h incubation, media that contained low glucose was reduced to almost 0 mg/dL, media that contained high glucose remained significantly higher at ∼275 mg/dL, and media that contained middle glucose remained closer to physiological range. AngII treatment enhanced glucose consumption in AFs and VSMCs but not in ECs. Enhanced extracellular acidification rate by AngII was also observed in AFs. In AFs, AngII induction of target proteins at 48 h varied depending on the glucose concentration used. In low glucose media, induction of glucose regulatory protein 78 or hexokinase II was highest, whereas induction of VCAM-1 was lowest. Utilization of specific inhibitors further suggests essential roles of angiotensin II type-1 receptor and glycolysis in AngII-induced fibroblast activation. Overall, this study demonstrates a high risk of hypo- or hyperglycemic conditions when standard low or high glucose media is used with vascular cells. Moreover, these conditions may significantly alter experimental outcomes. Media glucose concentration should be monitored during any culture experiments and utilization of middle glucose media is recommended for all vascular cell types.

Reward and immune responses in adolescent females following experimental traumatic brain injury

The pathology of traumatic brain injury (TBI) adversely affects many brain regions, often resulting in the development of comorbid psychiatric disorders including substance use disorders (SUD). Although traditionally thought to be an epidemic that predominantly affects males, recent clinical studies report females have higher rates of concussions and longer recovery times than males. Yet, how neurotrauma, particularly deep within the brain, between the sexes is differentially manifested remains largely unknown. The risk of TBI peaks during adolescence when neuronal networks that regulate reward behaviors are not fully developed. Previously, using the conditioned place preference (CPP) assay, we found that adolescent TBI increased susceptibility to the rewarding effects of cocaine in male mice. Further, we observed augmented inflammatory profiles, increased microglial phagocytosis of neuronal proteins, and decreased neuronal spine density in the NAc. Notably, the extent of sex differences in SUD susceptibility following TBI has not be investigated. Thus, here we ask the central question of whether the adolescent TBI-induced neuroinflammatory profile at reward centers is divergent in a sex-dependent manner. Using the CPP assay, we found that female mice with high levels of female sex hormones at the time of adolescent TBI demonstrated neuroprotection against increased sensitivity to the rewarding effects of cocaine. These studies also provide evidence of significantly reduced microglial activation and phagocytosis of neuronal proteins within the NAc of females. Overall, our results offer crucial insight into how adolescent TBI impacts the reward pathway in a sex depending manner that could explain a vulnerability to addiction-like behavior.

Road traffic offending and the introduction of speed cameras in England: the first self-report survey

There is some evidence to suggest that the use of speed cameras to enforce speed limits can lead to a decrease in both speed violations and road accidents. The precise effects of such measures, however, are unclear. This paper describes an initial survey of driver attitudes and behaviour conducted following the experimental introduction of speed cameras in the United Kingdom. The survey was designed to determine, by means of drivers' self-reports, (a) to what extent drivers' choice of speed had changed due to the presence of speed cameras, and whether this change generalised to areas where cameras were absent; (b) the relationship between individual differences and the influence of the cameras; and (c) drivers' opinions of the use of cameras. Five hundred and twenty-four subjects completed a brief questionnaire. Overall, the results indicate that the presence of speed cameras is effective in reducing the speeds adopted by some drivers and that this effect, to some extent, generalises to areas without cameras. However, it is also apparent that those drivers who report adopting the most excessive speeds in general are the most likely to report driving more slowly in the presence of cameras, but no differently or faster in other areas. Overall, drivers in this sample expressed more positive than negative views about the presence of speed cameras. The implications of the results for the widespread introduction of speed cameras are discussed.