Effect of sodium-glucose co-transporter-2 inhibitors on impaired ventricular repolarization in people with Type 2 diabetes

AIMS

To test the hypothesis that treatment with a sodium-glucose co-transporter-2 inhibitor would reverse ventricular repolarization heterogeneity, a predictor of cardiovascular mortality, in people with Type 2 diabetes.

METHODS

We retrospectively analysed changes in indices of ventricular repolarization before and after treatment with a sodium-glucose co-transporter-2 inhibitor in 46 people with Type 2 diabetes.

RESULTS

Sodium-glucose co-transporter-2 inhibitor treatment reduced HbA_1c concentration [62±13 mmol/mol (7.7±1.2%) vs 59±16 mmol/mol (7.5±1.4%)], body weight (77.8±13.9 vs 74.7±12.5 kg) and systolic blood pressure (133±18 vs 126±12 mmHg) in the study participants. Heart rate and QTc interval were not changed by sodium-glucose co-transporter-2 inhibitor treatment, but QTc dispersion was significantly reduced (median, 48.8 vs 44.2 ms). Sodium-glucose co-transporter-2 inhibitor treatment reversed QTc dispersion more in participants who had larger QTc dispersion before the treatment. Changes in systolic blood pressure (Spearman's ρ= 0.319; P=0.031), but not in HbA_1c concentration, were correlated with changes in QTc dispersion after sodium-glucose co-transporter-2 inhibitor treatment.

CONCLUSIONS

The findings suggest that sodium-glucose co-transporter-2 inhibitor treatment reverses ventricular repolarization heterogeneity in people with Type 2 diabetes, independently of its effect on glycaemic control. The favourable effect on ventricular repolarization heterogeneity could be the mechanism by which empaglifozin reduced cardiovascular events in a recent study.

Vascularised fibular grafts for reconstruction of extremity bone defects after resection of bone and soft-tissue tumours : a single institutional study of 49 patients

AIMS

The aims of this study were to analyse the long-term outcome of vascularised fibular graft (VFG) reconstruction after tumour resection and to evaluate the usefulness of the method.

PATIENTS AND METHODS

We retrospectively reviewed 49 patients who had undergone resection of a sarcoma and reconstruction using a VFG between 1988 and 2015. Their mean follow-up was 98 months (5 to 317). Reconstruction was with an osteochondral graft (n = 13), intercalary graft (n = 12), inlay graft (n = 4), or resection arthrodesis (n = 20). We analysed the oncological and functional outcome, and the rate of bony union and complications.

RESULTS

Five- and ten-year overall survival rates were 89% and 86%, respectively. Local recurrence occurred in two patients. Eight patients developed pulmonary metastases. Bone union was achieved in 44 patients (90%). Fracture occurred in six patients (12%), infection in three (6%), and nonunion in five (10%). The mean Musculoskeletal Tumor Society (MSTS) scores were as follows: osteochondral graft 70%; intercalary graft 73%; inlay graft 89%; and resection arthrodesis 83%.

CONCLUSION

Although associated with a relatively high rate of complications, each reconstruction method is useful, with a high rate of successful limb salvage and a good long-term functional outcome. Cite this article: Bone Joint J 2017;99-B:1237-43.

ICTV Virus Taxonomy Profile: Picornaviridae

The family Picornaviridae comprises small non-enveloped viruses with RNA genomes of 6.7 to 10.1 kb, and contains >30 genera and >75 species. Most of the known picornaviruses infect mammals and birds, but some have also been detected in reptiles, amphibians and fish. Many picornaviruses are important human and veterinary pathogens and may cause diseases of the central nervous system, heart, liver, skin, gastrointestinal tract or upper respiratory tract. Most picornaviruses are transmitted by the faecal–oral or respiratory routes. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the taxonomy of the Picornaviridae, which is available at www.ictv.global/report/picornaviridae.

A novel rare variant R292H in RTN4R affects growth cone formation and possibly contributes to schizophrenia susceptibility

Reticulon 4 receptor (RTN4R) plays an essential role in regulating axonal regeneration and plasticity in the central nervous system through the activation of rho kinase, and is located within chromosome 22q11.2, a region that is known to be a hotspot for schizophrenia (SCZ) and autism spectrum disorder (ASD). Recently, rare variants such as copy-number variants and single-nucleotide variants have been a focus of research because of their large effect size associated with increased susceptibility to SCZ and ASD and the possibility of elucidating the pathophysiology of mental disorder through functional analysis of the discovered rare variants. To discover rare variants with large effect size and to evaluate their role in the etiopathophysiology of SCZ and ASD, we sequenced the RTN4R coding exons with a sample comprising 370 SCZ and 192 ASD patients, and association analysis using a large number of unrelated individuals (1716 SCZ, 382 ASD and 4009 controls). Through this mutation screening, we discovered four rare (minor allele frequency <1%) missense mutations (R68H, D259N, R292H and V363M) of RTN4R. Among these discovered rare mutations, R292H was found to be significantly associated with SCZ (P=0.048). Furthermore, in vitro functional assays showed that the R292H mutation affected the formation of growth cones. This study strengthens the evidence for association between rare variants within RTN4R and SCZ, and may shed light on the molecular mechanisms underlying the neurodevelopmental disorder.

Rare genetic variants in CX3CR1 and their contribution to the increased risk of schizophrenia and autism spectrum disorders

CX3CR1, a G protein-coupled receptor solely expressed by microglia in the brain, has been repeatedly reported to be associated with neurodevelopmental disorders including schizophrenia (SCZ) and autism spectrum disorders (ASD) in transcriptomic and animal studies but not in genetic studies. To address the impacts of variants in CX3CR1 on neurodevelopmental disorders, we conducted coding exon-targeted resequencing of CX3CR1 in 370 Japanese SCZ and 192 ASD patients using next-generation sequencing technology, followed by a genetic association study in a sample comprising 7054 unrelated individuals (2653 SCZ, 574 ASD and 3827 controls). We then performed in silico three-dimensional (3D) structural modeling and in vivo disruption of Akt phosphorylation to determine the impact of the detected variant on CX3CR1-dependent signal transduction. We detected a statistically significant association between the variant Ala55Thr in CX3CR1 with SCZ and ASD phenotypes (odds ratio=8.3, P=0.020). A 3D structural model indicated that Ala55Thr could destabilize the conformation of the CX3CR1 helix 8 and affect its interaction with a heterotrimeric G protein. In vitro functional analysis showed that the CX3CR1-Ala55Thr mutation inhibited cell signaling induced by fractalkine, the ligand for CX3CR1. The combined data suggested that the variant Ala55Thr in CX3CR1 might result in the disruption of CX3CR1 signaling. Our results strengthen the association between microglia-specific genes and neurodevelopmental disorders.