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AbstractBackgroundVorinostat combined with retinoids produces additive antitumor effects in preclinical studies of neuroblastoma. Higher systemic exposures of vorinostat than achieved in pediatric phase I trials with continuous daily dosing are necessary for in vivo increased histone acetylation and cytotoxic activity. We conducted a phase I trial in children with relapsed/refractory neuroblastoma to determine the maximum tolerated dose (MTD) of vorinostat on an interrupted schedule, escalating beyond the previously identified pediatric MTD.MethodsIsotretinoin (cis‐13‐retinoic acid) 80 mg/m2/dose was administered by mouth twice daily on days 1–14 in combination with escalating doses of daily vorinostat up to 430 mg/m2/dose (days 1–4; 8–11) in each 28‐day cycle using the standard 3 + 3 design. Vorinostat pharmacokinetic testing and histone acetylation assays were performed.ResultsTwenty‐nine patients with refractory or relapsed neuroblastoma were enrolled and 28 were evaluable for dose escalation decisions. Median number of cycles completed was two (range 1–15); 11 patients received four or more cycles. Three patients experienced cycle 1 dose‐limiting toxicities. A total of 18 patients experienced grade 3/4 toxicities related to study therapy. The maximum intended dose of vorinostat (430 mg/m2/day, days 1–4; 8–11) was tolerable and led to increased histone acetylation in surrogate tissues when compared to lower doses of vorinostat (P = 0.009). No objective responses were seen.ConclusionsIncreased dose vorinostat (430 mg/m2/day) on an interrupted schedule is tolerable in combination with isotretinoin. This dose led to increased vorinostat exposures and demonstrated increased histone acetylation. Prolonged stable disease in patients with minimal residual disease warrants further investigation.

Summary Nivolumab, a monoclonal antibody against programmed cell death-1 receptor, is increasingly used in advanced cancers. While nivolumab use enhances cancer therapy, it is associated with increased immune-related adverse events. We describe an elderly man who presented in ketoacidosis after receiving nivolumab for metastatic renal cell carcinoma. On presentation, he was hyperpneic and laboratory analyses showed hyperglycemia and anion-gapped metabolic acidosis consistent with diabetic ketoacidosis. No other precipitating factors, besides nivolumab, were identified. Pre-nivolumab blood glucose levels were normal. The patient responded to treatment with intravenous fluids, insulin and electrolyte replacement. He was diagnosed with insulin-dependent autoimmune diabetes mellitus secondary to nivolumab. Although nivolumab was stopped, he continued to require multiple insulin injection therapy till his last follow-up 7 months after presentation. Clinicians need to be alerted to the development of diabetes mellitus and diabetic ketoacidosis in patients receiving nivolumab. Learning points: Diabetic ketoacidosis should be considered in the differential of patients presenting with metabolic acidosis following treatment with antibodies to programmed cell death-1 receptor (anti-PD-1). Autoimmune islet cell damage is the presumed mechanism for how insulin requiring diabetes mellitus can develop de novo following administration of anti-PD-1. Because anti-PD-1 works by the activation of T-cells and reduction of ‘self-tolerance’, other autoimmune disorders are likely to be increasingly recognized with increased use of these agents.

SummaryBackgroundAlthough obesity affects approximately one in five youths, only a fraction is treated in pediatric weight management clinics. Characteristics distinguishing youth with obesity who seek weight management treatment from those who do not are largely unknown. Yet identification of specific health characteristics which differentiate treatment‐seeking from non‐treatment seeking youth with obesity may shed light on underlying motivations for pursuing treatment.ObjectivesCompare the cardiometabolic profiles of an obesity treatment‐seeking sample of youth to a population‐based sample of youth with obesity, while controlling for body mass index (BMI).MethodsThis cross‐sectional study included participants, ages 12–17 years, with obesity from the Pediatric Obesity and Weight Evaluation Registry (POWER) and National Health and Nutrition Examination Survey, representing the treatment‐seeking and population samples, respectively. Mean differences were calculated for systolic and diastolic blood pressure percentiles, total cholesterol, low‐density and high‐density lipoprotein‐cholesterol, triglycerides, fasting glucose, glycated hemoglobin and alanine aminotransferase, while adjusting for age, sex, race/ethnicity, insurance status, and multiple of the 95th BMI percentile.ResultsThe POWER and National Health and Nutrition Examination Survey cohorts included 1,823 and 617 participants, respectively. The POWER cohort had higher systolic blood pressure percentile (mean difference 17.4, 95% confidence interval [14.6, 20.1], p < 0.001), diastolic blood pressure percentile (21.8 [19, 24.5], p < 0.001), triglycerides (42.3 [28, 56.5], p < 0.001) and alanine aminotransferase (7.5 [5.1, 9.8], p < 0.001) and lower fasting glucose (−6.9 [−8.2, −5.6], p < 0.001) and high‐density lipoprotein‐cholesterol (−2.3 [−3.8, −0.9], p < 0.002). There were no differences in total cholesterol or low‐density lipoprotein‐cholesterol or clinical differences in glycated hemoglobin.ConclusionFor a given BMI, obesity treatment‐seeking youth are more adversely affected by cardiometabolic risk factors than the general population of youth with obesity. This suggests that treatment‐seeking youth may represent a distinct group that is at particularly high risk for the development of future cardiometabolic disease.

ABSTRACT Mutations in genes encoding ion channels have increasingly been identified to cause disease conditions collectively termed channelopathies. Recognizing the molecular basis of an ion channel disease has provided new opportunities for screening, early diagnosis, and therapy of such conditions. This synopsis provides an overview of progress in the identification of molecular defects in inwardly rectifying potassium (Kir) channels. Structurally and functionally distinct from other channel families, Kir channels are ubiquitously expressed and serve functions as diverse as regulation of resting membrane potential, maintenance of K + homeostasis, control of heart rate, and hormone secretion. In humans, persistent hyperinsulinemic hypoglycemia of infancy, a disorder affecting the function of pancreatic β cells, and Bartter's syndrome, characterized by hypokalemic alkalosis, hypercalciuria, increased serum aldosterone, and plasma renin activity, are the two major diseases linked so far to mutations in a Kir channel or associated protein. In addition, the weaver phenotype, a neurological disorder in mice, has also been associated with mutations in a Kir channel subtype. Further genetic linkage analysis and full understanding of the consequence that a defect in a Kir channel would have on disease pathogenesis are among the priorities in this emerging field of molecular medicine.—Abraham, M. R., Jahangir, A., Alekseev, A. E., Terzic, A. Channelopathies of inwardly rectifying potassium channels. FASEB J . 13, 1901–1910 (1999)

Objectives: Transfusion-associated circulatory overload is characterized by hydrostatic pulmonary edema following blood transfusion. Restrictive transfusion practice may affect the occurrence and severity of transfusion-associated circulatory overload in critically ill patients. We sought to examine contemporary risk factors and outcomes for transfusion-associated circulatory overload. Design: Case-control study. Setting: Four tertiary care hospitals. Patients: We prospectively enrolled 200 patients with transfusion-associated circulatory overload identified by active surveillance and 405 controls matched by transfusion intensity. Interventions: None. Measurements and Main Results: Among 20,845 transfused patients who received 128,263 blood components from May 2015 until July 2016, transfusion-associated circulatory overload incidence was one case per 100 transfused patients. In addition to cardiovascular comorbidities, multivariable analysis identified the following independent predictors of transfusion-associated circulatory overload: acute kidney injury, emergency surgery, pretransfusion diuretic use, and plasma transfusion—the latter especially in females. Compared with matched controls, transfusion-associated circulatory overload cases were more likely to require mechanical ventilation (71% vs 49%; p < 0.001), experienced longer intensive care and hospital lengths of stay following transfusion, and had higher mortality (21% vs 11%; p = 0.02) even after adjustment for other potentially confounding variables. Conclusions: Despite restrictive transfusion practice, transfusion-associated circulatory overload remains a frequent complication of transfusion and is an independent risk factor for in-hospital morbidity and mortality. In addition to cardiovascular and renal risk factors, plasma transfusion was associated with transfusion-associated circulatory overload after controlling for other covariates. Additional research is needed to examine the benefit of reduced erythrocyte or plasma exposure in patients at high risk for transfusion-associated circulatory overload.

ATP-sensitive K+ (KATP) channels are present at high density in membranes of cardiac cells where they regulate cardiac function during cellular metabolic impairment. KATP channels have been implicated in the shortening of the action potential duration and the cellular loss of K+ that occurs during metabolic inhibition. KATP channels have been associated with the cardioprotective mechanism of ischemia-related preconditioning. Intracellular ATP (ATPi) is the main regulator of KATP channels. ATPi has two functions: 1) to close the channel (ligand function) and 2) in the presence of Mg2+, to maintain the activity of KATP channels (presumably through an enzymatic reaction). KATP channel activity is modulated by intracellular nucleoside diphosphates that antagonize the ATPi-induced inhibition of channel opening or induce KATP channels to open. How nucleotides will affect KATP channels depends on the state of the channel. K+ channel-opening drugs are pharmacological agents that enhance KATP channel activity through different mechanisms and have great potential in the management of cardiovascular conditions. KATP channel activity is also modulated by neurohormones. Adenosine, through the activation of a GTP-binding protein, antagonizes the ATPi-induced channel closure. Understanding the molecular mechanisms that underlie KATP channel regulation should prove essential to further define the function of KATP channels and to elucidate the pharmacological regulation of this channel protein. Since the molecular structure of the KATP channel has now become available, it is anticipated that major progress in the KATP channel field will be achieved.

Discovered in the cardiac sarcolemma, ATP-sensitive K+(KATP) channels have more recently also been identified within the inner mitochondrial membrane. Yet the consequences of mitochondrial KATPchannel activation on mitochondrial function remain partially documented. Therefore, we isolated mitochondria from rat hearts and used K+channel openers to examine the effect of mitochondrial KATPchannel opening on mitochondrial membrane potential, respiration, ATP generation, Ca2+transport, and matrix volume. From a mitochondrial membrane potential of −180 ± 15 mV, K+channel openers, pinacidil (100 μM), cromakalim (25 μM), and levcromakalim (20 μM), induced membrane depolarization by 10 ± 7, 25 ± 9, and 24 ± 10 mV, respectively. This effect was abolished by removal of extramitochondrial K+or application of a KATPchannel blocker. K+channel opener-induced membrane depolarization was associated with an increase in the rate of mitochondrial respiration and a decrease in the rate of mitochondrial ATP synthesis. Furthermore, treatment with a K+channel opener released Ca2+from mitochondria preloaded with Ca2+, an effect also dependent on extramitochondrial K+concentration and sensitive to KATPchannel blockade. In addition, K+channel openers, cromakalim and pinacidil, increased matrix volume and released mitochondrial proteins, cytochrome cand adenylate kinase. Thus, in isolated cardiac mitochondria, KATPchannel openers depolarized the membrane, accelerated respiration, slowed ATP production, released accumulated Ca2+, produced swelling, and stimulated efflux of intermembrane proteins. These observations provide direct evidence for a role of mitochondrial KATPchannels in regulating functions vital for the cardiac mitochondria.