Canagliflozin for primary and secondary prevention of cardiovascular events: results from the CANVAS Program (Canagliflozin Cardiovascular Assessment Study)

BACKGROUND : Canagliflozin is a sodium glucose cotransporter 2 inhibitor that significantly reduces the composite of cardiovascular death, nonfatal myocardial infarction, or nonfatal stroke in patients with type 2 diabetes mellitus and elevated cardiovascular risk. The comparative effects among participants with and without a history of cardiovascular disease (secondary versus primary prevention) were prespecified for evaluation. METHODS : The CANVAS Program (Canagliflozin Cardiovascular Assessment Study) randomly assigned 10 142 participants with type 2 diabetes mellitus to canagliflozin or placebo. The primary prevention cohort comprised individuals ≥50 years of age with ≥2 risk factors for cardiovascular events but with no prior cardiovascular event, and the secondary prevention cohort comprised individuals ≥30 years of age with a prior cardiovascular event. The primary end point was a composite of cardiovascular death, nonfatal myocardial infarction, or nonfatal stroke. Secondary outcomes included heart failure hospitalization and a renal composite (40% reduction in estimated glomerular filtration rate, renal replacement therapy, or renal death). RESULTS : Primary prevention participants (N=3486; 34%) were younger (63 versus 64 years of age), were more often female (45% versus 31%), and had a longer duration of diabetes mellitus (14 versus 13 years) compared with secondary prevention participants (N=6656; 66%). The primary end point event rate was higher in the secondary prevention group compared with the primary prevention group (36.9 versus 15.7/1000 patient-years, P<0.001). In the total cohort, the primary end point was reduced with canagliflozin compared with placebo (26.9 versus 31.5/1000 patient-years; hazard ratio [HR], 0.86; 95% confidence interval [CI], 0.75-0.97; P<0.001 for noninferiority, P=0.02 for superiority) with no statistical evidence of heterogeneity (interaction P value=0.18) between the primary (HR, 0.98; 95% CI, 0.74-1.30) and secondary prevention (HR, 0.82; 95% CI, 0.72-0.95) cohorts. Renal outcomes (HR, 0.59; 95% CI, 0.44-0.79 versus HR, 0.63; 95% CI, 0.39-1.02; interaction P value=0.73) and heart failure hospitalization (HR, 0.68; 95% CI, 0.51-0.90 versus HR, 0.64; 95% CI, 0.35-1.15; interaction P value=0.91) were similarly reduced in the secondary and primary prevention cohorts, respectively. Lower extremity amputations were similarly increased in the secondary and primary prevention cohorts (HR, 2.07; 95% CI, 1.43-3.00 versus HR, 1.52; 95% CI, 0.70-3.29; interaction P value=0.63). CONCLUSIONS : Patients with type 2 diabetes mellitus and prior cardiovascular events had higher rates of cardiovascular outcomes compared with the primary prevention patients. Canagliflozin reduced cardiovascular and renal outcomes with no statistical evidence of heterogeneity of the treatment effect across the primary and secondary prevention groups. Additional studies will provide further insights into the effects of canagliflozin in these patient populations. CLINICAL TRIAL REGISTRATION : URL: https://www.clinicaltrials.gov. Unique identifiers: NCT01032629 and NCT01989754

Structure and Regulation of Type II Calcium/Calmodulin-dependent Protein Kinase in Central Nervous System Neurons

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GABA Expression and Regulation by Sensory Experience in the Developing Visual System

The developing retinotectal system of the Xenopus laevis tadpole is a model of choice for studying visual experience-dependent circuit maturation in the intact animal. The neurotransmitter gamma-aminobutyric acid (GABA) has been shown to play a critical role in the formation of sensory circuits in this preparation, however a comprehensive neuroanatomical study of GABAergic cell distribution in the developing tadpole has not been conducted. We report a detailed description of the spatial expression of GABA immunoreactivity in the Xenopus laevis tadpole brain at two key developmental stages: stage 40/42 around the onset of retinotectal innervation and stage 47 when the retinotectal circuit supports visually-guided behavior. During this period, GABAergic neurons within specific brain structures appeared to redistribute from clusters of neuronal somata to a sparser, more uniform distribution. Furthermore, we found that GABA levels were regulated by recent sensory experience. Both ELISA measurements of GABA concentration and quantitative analysis of GABA immunoreactivity in tissue sections from the optic tectum show that GABA increased in response to a 4 hr period of enhanced visual stimulation in stage 47 tadpoles. These observations reveal a remarkable degree of adaptability of GABAergic neurons in the developing brain, consistent with their key contributions to circuit development and function

Age-Dependent Targeting of Protein Phosphatase 1 to Ca2+/Calmodulin-Dependent Protein Kinase II by Spinophilin in Mouse Striatum

Mechanisms underlying age-dependent changes of dendritic spines on striatal medium spiny neurons are poorly understood. Spinophilin is an F-actin- and protein phosphatase 1 (PP1)-binding protein that targets PP1 to multiple downstream effectors to modulate dendritic spine morphology and function. We found that calcium/calmodulin-dependent protein kinase II (CaMKII) directly and indirectly associates with N- and C-terminal domains of spinophilin, but F-actin can displace CaMKII from the N-terminal domain. Spinophilin co-localizes PP1 with CaMKII on the F-actin cytoskeleton in heterologous cells, and spinophilin co-localizes with synaptic CaMKII in neuronal cultures. Thr286 autophosphorylation enhances the binding of CaMKII to spinophilin in vitro and in vivo. Although there is no change in total levels of Thr286 autophosphorylation, maturation from postnatal day 21 into adulthood robustly enhances the levels of CaMKII that co-immunoprecipitate with spinophilin from mouse striatal extracts. Moreover, N- and C-terminal domain fragments of spinophilin bind more CaMKII from adult vs. postnatal day 21 striatal lysates. Total levels of other proteins that interact with C-terminal domains of spinophilin decrease during maturation, perhaps reducing competition for CaMKII binding to the C-terminal domain. In contrast, total levels of α-internexin and binding of α-internexin to the spinophilin N-terminal domain increases with maturation, perhaps bridging an indirect interaction with CaMKII. Moreover, there is an increase in the levels of myosin Va, α-internexin, spinophilin, and PP1 in striatal CaMKII immune complexes isolated from adult and aged mice compared to those from postnatal day 21. These changes in spinophilin/CaMKII interactomes may contribute to changes in striatal dendritic spine density, morphology, and function during normal postnatal maturation and aging

Genotype-Specific Differences between Mouse CNS Stem Cell Lines Expressing Frontotemporal Dementia Mutant or Wild Type Human Tau

Stem cell (SC) lines that capture the genetics of disease susceptibility provide new research tools. To assess the utility of mouse central nervous system (CNS) SC-containing neurosphere cultures for studying heritable neurodegenerative disease, we compared neurosphere cultures from transgenic mice that express human tau with the P301L familial frontotemporal dementia (FTD) mutation, rTg(tauP301L)4510, with those expressing comparable levels of wild type human tau, rTg(tauwt)21221. rTg(tauP301L)4510 mice express the human tauP301L variant in their forebrains and display cellular, histological, biochemical and behavioral abnormalities similar to those in human FTD, including age-dependent differences in tau phosphorylation that distinguish them from rTg(tauwt)21221 mice. We compared FTD-hallmark tau phosphorylation in neurospheres from rTg(tauP301L)4510 mice and from rTg(tauwt)21221 mice. The tau genotype-specific phosphorylation patterns in neurospheres mimicked those seen in mice, validating use of neurosphere cultures as models for studying tau phosphorylation. Genotype-specific tau phosphorylation was observed in 35 independent cell lines from individual fetuses; tau in rTg(tauP301L)4510 cultures was hypophosphorylated in comparison with rTg(tauwt)21221 as was seen in young adult mice. In addition, there were fewer human tau-expressing cells in rTg(tauP301L)4510 than in rTg(tauwt)21221 cultures. Following differentiation, neuronal filopodia-spine density was slightly greater in rTg(tauP301L)4510 than rTg(tauwt)21221 and control cultures. Together with the recapitulation of genotype-specific phosphorylation patterns, the observation that neurosphere lines maintained their cell line-specific-differences and retained SC characteristics over several passages supports the utility of SC cultures as surrogates for analysis of cellular disease mechanisms

Pharmacology and therapeutic implications of current drugs for type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a global epidemic that poses a major challenge to health-care systems. Improving metabolic control to approach normal glycaemia (where practical) greatly benefits long-term prognoses and justifies early, effective, sustained and safety-conscious intervention. Improvements in the understanding of the complex pathogenesis of T2DM have underpinned the development of glucose-lowering therapies with complementary mechanisms of action, which have expanded treatment options and facilitated individualized management strategies. Over the past decade, several new classes of glucose-lowering agents have been licensed, including glucagon-like peptide 1 receptor (GLP-1R) agonists, dipeptidyl peptidase 4 (DPP-4) inhibitors and sodium/glucose cotransporter 2 (SGLT2) inhibitors. These agents can be used individually or in combination with well-established treatments such as biguanides, sulfonylureas and thiazolidinediones. Although novel agents have potential advantages including low risk of hypoglycaemia and help with weight control, long-term safety has yet to be established. In this Review, we assess the pharmacokinetics, pharmacodynamics and safety profiles, including cardiovascular safety, of currently available therapies for management of hyperglycaemia in patients with T2DM within the context of disease pathogenesis and natural history. In addition, we briefly describe treatment algorithms for patients with T2DM and lessons from present therapies to inform the development of future therapies

Diabetic ketoacidosis

Diabetic ketoacidosis (DKA) is the most common acute hyperglycaemic emergency in people with diabetes mellitus. A diagnosis of DKA is confirmed when all of the three criteria are present — ‘D’, either elevated blood glucose levels or a family history of diabetes mellitus; ‘K’, the presence of high urinary or blood ketoacids; and ‘A’, a high anion gap metabolic acidosis. Early diagnosis and management are paramount to improve patient outcomes. The mainstays of treatment include restoration of circulating volume, insulin therapy, electrolyte replacement and treatment of any underlying precipitating event. Without optimal treatment, DKA remains a condition with appreciable, although largely preventable, morbidity and mortality. In this Primer, we discuss the epidemiology, pathogenesis, risk factors and diagnosis of DKA and provide practical recommendations for the management of DKA in adults and children