The impact of ATP-sensitive potassium channel modulation on mitochondria in a Parkinson's disease model using SH-SY5Y cells depends on their differentiation state.

Inward rectifying potassium channels sensitive to ATP levels (KATP) have been the subject of investigation for several decades. Modulators of KATP channels are well-established treatments for metabolic as well as cardiovascular diseases. Experimental studies have also shown the potential of KATP modulation in neurodegenerative disorders. However, to date, data regarding the effects of KATP antagonists/agonists in experiments related to neurodegeneration remain inconsistent. The main source of confusion in evaluating available data seems to be the choice of experimental models. The present study aims to provide a comprehensive understanding of the effects of both opening and blocking KATP channels in two forms of SH-SY5Y cells. Our results offer valuable insights into the significance of metabolic differences between differentiated and non-differentiated SH-SY5Y cells, particularly in the context of glibenclamide and diazoxide effects under normal conditions and during the initiation of pathological events simulating Parkinson's disease in vitro. We emphasize the analysis of mitochondrial functions and changes in mitochondrial network morphology. The heightened protein expression of KATP channels identified in non-differentiated SH-SY5Y cells seems to be a platform for a more significant impact of KATP modulators in this cell type. The efficiency of rotenone treatment in inducing morphological changes in the mitochondrial network depends on the differentiation status of SH-SY5Y cells.

Low-dose diazoxide is safe and effective in infants with transient hyperinsulinism.

OBJECTIVE: Transient hyperinsulinism (THI) is the most common form of recurrent hypoglycaemia in neonates beyond the first week of life. Although self-resolving, treatment can be required. Consensus guidelines recommend the lower end of the diazoxide 5-15 mg/kg/day range in THI to reduce the risk of adverse events. We sought to determine if doses <5 mg/kg/day of diazoxide can be effective in THI. DESIGN, PATIENTS, MEASURMENTS: Infants with THI (duration <6 months) were treated with low-dose diazoxide from October 2015 to February 2021. Dosing was based on weight at diazoxide start: 2 mg/kg/day in infants 1000-2000 g (cohort 1), 3 mg/kg/day in those 2000-3500 g (cohort 2) and 5 mg/kg/day in those >3500 g. RESULTS: A total of 73 infants with THI (77% male, 33% preterm, 52% small-for-gestational age) were commenced on diazoxide at a median age of 11 days (range 3-43) for a median duration of 4 months (0.3-6.8), with no difference between cohorts. The mean effective diazoxide dose was 3 mg/kg/day (range 1.5-10); 35% (26/73) required an increase from their starting dose, including 60% (9/15) of cohort 1. There was no association between perinatal stress risk factors or treatment-related characteristics and dose increase. Adverse events occurred in 13 patients (18%); oedema (12%) and hyponatraemia (5%) were the most common. Two infants developed suspected necrotising enterocolitis (NEC); none had pulmonary hypertension. CONCLUSION: Diazoxide doses <5 mg/kg/day are effective in THI. While the nature of the association between diazoxide and NEC was unclear, other adverse events were mild. We suggest considering starting doses as low as 2-3 mg/kg/day in THI to balance the side effect risk while maintaining euglycaemia.

Mitochondrial connexin43 and mitochondrial KATP channels modulate triggered arrhythmias in mouse ventricular muscle.

Connexin43 (Cx43) exits as hemichannels in the inner mitochondrial membrane. We examined how mitochondrial Cx43 and mitochondrial KATP channels affect the occurrence of triggered arrhythmias. To generate cardiac-specific Cx43-deficient (cCx43-/-) mice, Cx43flox/flox mice were crossed with α-MHC (Myh6)-cre+/- mice. The resulting offspring, Cx43flox/flox/Myh6-cre+/- mice (cCx43-/- mice) and their littermates (cCx43+/+ mice), were used. Trabeculae were dissected from the right ventricles of mouse hearts. Cardiomyocytes were enzymatically isolated from the ventricles of mouse hearts. Force was measured with a strain gauge in trabeculae (22°C). To assess arrhythmia susceptibility, the minimal extracellular Ca2+ concentration ([Ca2+]o,min), at which arrhythmias were induced by electrical stimulation, was determined in trabeculae. ROS production was estimated with 2',7'-dichlorofluorescein (DCF), mitochondrial membrane potential with tetramethylrhodamine methyl ester (TMRM), and Ca2+ spark frequency with fluo-4 and confocal microscopy in cardiomyocytes. ROS production within the mitochondria was estimated with MitoSoxRed and mitochondrial Ca2+ with rhod-2 in trabeculae. Diazoxide was used to activate mitochondrial KATP. Most of cCx43-/- mice died suddenly within 8 weeks. Cx43 was present in the inner mitochondrial membrane in cCx43+/+ mice but not in cCx43-/- mice. In cCx43-/- mice, the [Ca2+]o,min was lower, and Ca2+ spark frequency, the slope of DCF fluorescence intensity, MitoSoxRed fluorescence, and rhod-2 fluorescence were higher. TMRM fluorescence was more decreased in cCx43-/- mice. Most of these changes were suppressed by diazoxide. In addition, in cCx43-/- mice, antioxidant peptide SS-31 and N-acetyl-L-cysteine increased the [Ca2+]o,min. These results suggest that Cx43 deficiency activates Ca2+ leak from the SR, probably due to depolarization of mitochondrial membrane potential, an increase in mitochondrial Ca2+, and an increase in ROS production, thereby causing triggered arrhythmias, and that Cx43 hemichannel deficiency may be compensated by activation of mitochondrial KATP channels in mouse hearts.

Diazoxide improves muscle function in association with improved dyslipidemia and decreased muscle oxidative stress in streptozotocin-induced diabetic rats.

AIM/INTRODUCTION: Diabetes Mellitus is a chronic degenerative disease, and its main biochemical characteristic is hyperglycemia due to impaired insulin secretion, resistance to peripheral actions of insulin, or both. Hyperglycemia causes dyslipidemia and stimulates oxidative damage, leading to the main symptoms, such as fatigue and culminates in diabetic complications. Previous studies have shown that ATP-sensitive potassium channels counteract muscle fatigue and metabolic stress in healthy mouse models. To determine the effect of diazoxide on muscle strength development during diabetes, we tested the effect of diazoxide in streptozotocin-diabetic rats in muscle function, lipid profile and oxidative stress biomarkers. MATERIALS AND METHODS: Wistar rats were divided into 4 groups of six animals each: (1) Control group, (2) diabetes group, (3) Control group + diazoxide, and (4) Diabetic + diazoxide (DB + DZX). 4 weeks after rats were sacrificed, soleus and extensor digitorum longus muscles (EDL) were extracted to prepare homogenates and serum was obtained for biochemical measurements. Oxidative damage was evaluated by the thiobarbituric acid method and the fluorescent for reactive oxygen species (ROS) probe 2,4-H2DCFDA, respectively. RESULTS: Diabetic rats with diazoxide administration showed an increase in the development of muscle strength in both muscles; in turn, the onset of fatigue was longer compared to the group of diabetic rats without treatment. Regarding the lipid profile, diazoxide decreased total cholesterol levels in the group of diabetic rats treated with diazoxide (x̅46.2 mg/dL) compared to the untreated diabetic group (x̅=104.4 mg/dL); secondly, diazoxide decreased triglyceride concentrations (x̅=105.3 mg/dL) compared to the untreated diabetic rats (x̅=412.2 mg/dL) as well as the levels of very low-density lipoproteins (x̅=20.4 mg/dL vs. x̅=82.44 mg/dL). Regarding the various markers of oxidative stress, the diabetic group treated with diazoxide was able to reduce the concentrations of TBARS and total reactive oxygen species as well as preserve the concentrations of reduced glutathione. CONCLUSION: Diazoxide administration in diabetic rats increases muscle strength development in EDL and soleus muscle, decreases fatigue, reduces cholesterol and triglyceride concentrations and improves oxidative stress parameters such as TBARS, ROS, and glutathione status.

When is it best to discontinue diazoxide in children with persistent hyperinsulinaemic hypoglycaemia and negative genetics for KATP channel gene variants?

Diazoxide is the first-line treatment in children with hyperinsulinaemic hypoglycaemia (HH); however, limited information is available on the duration of diazoxide treatment in children who require over 2 years of it. Hence, we retrospectively reviewed the clinical and biochemical aspects, as well as the duration of therapy and neurodevelopmental assessment, in genetically uncharacterised diazoxide-responsive HH patients admitted to a tertiary hospital over the last 16 years, who had successfully discontinued diazoxide and remained euglycaemic. To exclude transient HH forms, only patients that required diazoxide for over 2 years were studied. We identified a total of 17 patients (70% males), in whom HH was diagnosed between 1 day and 18 months of age, and 88% were born at term with a median birth weight of 3.79 kg. All children responded to diazoxide at a median dose of 11.5 mg/kg/day, and it was stopped at a median age of 8.5 years, with a median duration of therapy of 7.25 years. The cases that required diazoxide the longest manifested no specific biochemical or clinical characteristics. Fasting tests performed after diazoxide discontinuation showed no longer requirement of diazoxide in all the cases. A total of 64.7% of the children showed mild to moderate developmental delay. Therefore, it seems that long-term resolution of HH in children with negative genetics for KATP channel genes who required diazoxide for over 2 years will ensue, and thus regular evaluation is crucial. The possible molecular mechanisms involved are unclear.

Diazoxide during pregnancy and lactation: drug levels in maternal serum, cord blood, breast milk, and infant serum: a case report.

Safety information on diazoxide for pregnant and lactating women with hypoglycemia is limited. In this case report, we assessed diazoxide concentrations in maternal and infant blood, cord blood, and breast milk. We described a 30-year-old pregnant woman diagnosed with hypoglycemia due to nesidioblastosis at 4 months of age. Before becoming pregnant, she was treated with oral diazoxide (75-375 mg). All medications were discontinued after she was discovered to be pregnant. During gestational week 25, diazoxide treatment was resumed at 150-175 mg daily for repeated hypoglycemic episodes. Diazoxide administration was continued in combination with diet treatment until delivery. Glucose levels were well controlled. During gestational week 40, a male infant weighing 3069 g was delivered via spontaneous vaginal delivery with no pregnancy or neonatal complications. Diazoxide concentrations detected in maternal serum at 2.5-11.6 h after oral treatment ranged from 12.4 to 32.7 µg/mL. In cord blood, the diazoxide concentration was 18.5 µg/mL at 7.2 h after the last dose. During lactation, no hypoglycemia or hyperglycemia was observed. The approximate calculated ratio of diazoxide in breast milk and maternal serum was 0.09. The calculated daily infant dose was 0.47 mg/kg/day. The relative infant dose via breast milk ranged from 3.1% to 5.9%. Diazoxide transferred from maternal blood to the fetus across the placenta. It also transferred into breast milk, but there were no harmful effects on the infant.

MiR-21 participates in the neuroprotection of diazoxide against hypoxic-ischemia encephalopathy by targeting PDCD4.

BACKGROUND: Hypoxic-ischemic encephalopathy (HIE) is one of the leading causes of neonatal death and permanent neurological disability. Here, we designed to quest therapeutic effects of diazoxide (DZ) on HIE and its mechanism. METHODS: The cell model of HIE was established. CCK8 and flow cytometry were applied to test cell viability and apoptosis. RT-qPCR and western blotting was evaluated to the expression of miR-21, PDCD4, PI3K, and p-AKT/AKT. Commercial kits were employed to detect SOD, MDA, LDH. DCFH-DA was used to measure intracellular ROS. ELISA was performed to estimate IL-1ß, IL-6 and TNF-α. Dual-luciferase reporter gene and RIP assay were applied to confirm the binding relationships between miR-21 and PDCD4. RESULTS: In H19-7 cells and PC12 cells stimulated by OGD, with low cell viability, high apoptosis, miR-21 high expression and PDCD4 low expression. However, the functions were all reversed by DZ administration. Furthermore, miR-21 inhibitor could abolish the beneficial effects of DZ on OGD-induced cells. Besides, miR-21 could interact with PDCD4. In addition, PDCD4 involved with the regulation of DZ to OGD-induced cells via PI3K/AKT pathway. CONCLUSION: DZ enhanced miR-21 level and inhibited PDCD4 level via PI3K/AKT pathway to resisted HIE.

Preoperative treatment of benign insulinoma: diazoxide or somatostatin analogues?

Surgery is the ideal treatment of insulinoma. However, systemic therapy may be required to prevent severe preoperative hypoglycaemia, when surgery is contraindicated, delayed or refused and in case of unresectable metastatic disease. Diazoxide is commonly used but is not always effective and can cause serious side effects. Somatostatin analogues (octreotide and lanreotide) may be an alternative option. We report the case of a 27-year-old patient with insulinoma in whom diazoxide was compared with lanreotide before operation. A diagnosis of insulinoma was made on the basis of a fasting test and a 2 cm tumour confirmed in the body of the pancreas, with a high uptake of 111-In-pentreotide. Diazoxide was initiated and increased to a maximal tolerated dose of 450 mg/day. Because of dyspnoea and persisting hypoglycaemia, diazoxide was shifted to lanreotide 120 mg. All symptoms resolved without hypoglycaemia. According to the EORTC quality score of life, the score without treatment, under diazoxide, under lanreotide and after surgery were respectively 84.7, 73.3, 90.9 and 99.1. Thus, providing a positive Octreoscan, somatostatin analogues may be a safe, effective and well-tolerated option in patients with insulinoma refractory and/or intolerant to diazoxide or with a high risk of fluid retention.

Clinical characteristics, outcome, and predictors of neurological sequelae of persistent congenital hyperinsulinism: A single tertiary center experience.

AIM: Congenital hyperinsulinism (CHI) is a heterogeneous disease with variable genetic etiology, histopathology, and clinical phenotype. This study aims to describe the clinical characteristics of persistent CHI and evaluate long-term neurological outcome and its risk factors in a cohort of Egyptian children. METHODS: Clinical, genetic, and biochemical data of 42 patients with CHI were collected. Patients were invited for neurological assessment, electroencephalogram, and magnetic resonance imaging of the brain. RESULTS: ABCC8 mutation was found in (61%) of cases who underwent genetic testing (17/28). Five cases with homozygous biparental ABCC8 mutation responded to combined diazoxide and octreotide without needing surgery. Seven out of twenty-one patients who had pancreatectomy (33%) developed diabetes after a median period of 4.8 (range:1-10) years following surgery. Fifty-five percent of our patients had neurodevelopmental impairment at follow-up. Logistic regression analysis has shown that delayed referral to tertiary centre for more than 8 days, delayed diagnosis of CHI for more than 14 days and hospital admission for more than 30 days, are significant predictors of unfavorable neurological sequelae in CHI; (OR = 12.7 [2.56], p = 0.001), (OR = 12.7 [2.9-56], p = 0.001), and (OR = 3.8 [0.14.5], p = 0.043), respectively. CONCLUSIONS: ABCC8 mutation was the commonest genetic mutation underlying CHI in this study group. CHI cases with biparental homozygous ABCC8 mutation may show response to combined octreotide and diazoxide therapy. More than half of our patients had neurodevelopmental impairment at follow-up. Delayed referral to expert centre, delayed diagnosis and longer hospital stay are significant predictors of neurological disability in CHI cases.

Unusual presentation of an insulinoma in an elderly male patient.

Insulinoma is a rare neuroendocrine tumor originating from hypersecreting beta-cells of islets of Langerhans in the pancreas. We report a case of 72-year-old male, with chronic alcohol abuse, presenting with atypical features like refractory recurrent secondary generalized seizures and behavioral disturbances with increased irritability, initially mistreated as alcohol withdrawal. Detailed history, particularly the relationship of the symptoms with food intake, made us think of other causes of seizures. Fasting biochemical investigations and localizing studies helped clinch the diagnosis. The tumor was localized with the help of endoscopic ultrasonography and whole-body Ga68-DOTANOC PET-CT. The patient was treated conservatively with diazoxide and is doing well on follow-up. The present case report emphasizes the importance of detailed clinical history, more so in atypically presenting cases of refractory seizures. Insulinoma can be medically managed despite surgery being the gold standard curative treatment.

Diazoxide Needs Mitochondrial Connexin43 to Exert Its Cytoprotective Effect in a Cellular Model of CoCl2-Induced Hypoxia.

Hypoxia is the leading cause of death in cardiomyocytes. Cells respond to oxygen deprivation by activating cytoprotective programs, such as mitochondrial connexin43 (mCx43) overexpression and the opening of mitochondrial KATP channels, aimed to reduce mitochondrial dysfunction. In this study we used an in vitro model of CoCl2-induced hypoxia to demonstrate that mCx43 and KATP channels cooperate to induce cytoprotection. CoCl2 administration induces apoptosis in H9c2 cells by increasing mitochondrial ROS production, intracellular and mitochondrial calcium overload and by inducing mitochondrial membrane depolarization. Diazoxide, an opener of KATP channels, reduces all these deleterious effects of CoCl2 only in the presence of mCx43. In fact, our results demonstrate that in the presence of radicicol, an inhibitor of Cx43 translocation to mitochondria, the cytoprotective effects of diazoxide disappear. In conclusion, these data confirm that there exists a close functional link between mCx43 and KATP channels.

Diazoxide-Induced Neutropenia and Long-Term Follow-up in a Patient with Hyperinsulinemia-Hyperammonemia due to GLUD1 Mutation.

Hyperinsulinism/hyperammonemia (HI/HA) syndrome is caused by activating mutations in GLUD1 gene, and causes fasting as well as protein sensitive symptomatic hypoglycemia, in addition to persistently elevated plasma ammonia levels. First-line treatment is diazoxide, and most patients respond well to this agent, however side effects may be observed. The most frequent side effect of diazoxide is fluid retention and hypertrichosis, while hyperuricemia and hematologic side effects are observed less often. Herein, we report a case who had a heterozygous mutation of GLUD1 gene and who developed diazoxide related neutropenia 8 years after the start of treatment. On follow-up, leucopenia and mild neutropenia persisted and the treatment was changed to somatostatin analogues. However, she developed persistent severe symptomatic hypoglycemia and required diazoxide retreatment. A lower dose of diazoxide (6 mg/kg/day) successfully controlled hypoglycemia and cell counts increased even though they were not normalized. Neutropenia in current case presented after a long period of time of diazoxide use and this period is the longest defined in the literature. Long-term endocrine and hematologic follow-up of this patient up to 18 years old will also be presented.

Comparative meta-analysis of Kabuki syndrome with and without hyperinsulinaemic hypoglycaemia.

BACKGROUND AND OBJECTIVE: Kabuki syndrome (KS), caused by pathogenic variants in KMT2D or KDM6A, is associated with hyperinsulinaemic hypoglycaemia (HH) in 0.3%-4% of patients. We characterized the clinical, biochemical and molecular data of children with KS and HH compared to children with KS without HH in a multicentre meta-analysis. METHODS: Data of seven new and 17 already published children with KS and HH were compared to 373 recently published KS patients without HH regarding molecular and clinical characteristics. RESULTS: Seven new patients were identified with seven different pathogenic variants in KDM6A (n = 4) or KMT2D (n = 3). All presented with HH on the first day of life and were responsive to diazoxide. KS was diagnosed between 9 months and 14 years of age. In the meta-analysis, 24 KS patients with HH had a significantly higher frequency of variants in KDM6A compared to 373 KS patients without HH (50% vs 11.5%, P < .001), and KDM6A-KS was more likely to be associated with HH than KMT2D-KS (21.8% vs. 3.5%, P < .001). Sex distribution and other phenotypic features did not differ between KS with and without HH. CONCLUSION: The higher incidence of HH in KDM6A-KS compared to KMT2D-KS indicates that KDM6A loss of function variants predispose more specifically to beta cell dysfunction compared to KMT2D variants. As difficulties to assign syndromic characteristics to KS in early infancy often lead to delayed diagnosis, genetic testing for KS should be considered in children with HH, especially in the presence of other extrapancreatic/syndromic features.

Higher C-peptide levels and glucose requirements may identify neonates with transient hyperinsulinism hypoglycemia who will benefit from diazoxide treatment.

The aim of the study was to characterize factors that may serve as clinical tools to identify neonates with transient neonatal hyperinsulinism hypoglycemia (HH) who may benefit from diazoxide treatment. This retrospective study included 141 neonates with transient HH (93 males) of whom 34 (24%) were treated with diazoxide. Diazoxide treatment was started at median age of 13 days (range 5-35) and discontinued at median age of 42 days (range 14-224). The maximal dose was 7.1 ± 2.3 mg/kg/day. Diazoxide-treated neonates required a higher glucose infusion rate (GIR) compared with non-treated neonates (16.6 ± 3.4 vs. 10.4 ± 4.0 mg/kg/min, respectively, P < .01), had a longer duration of intravenous fluids (15.9 ± 9.3 vs. 7.8 ± 6.5 days, P < .01), a longer hospitalization (32.8 ± 22.7 vs. 20.4 ± 13.4 days, P < .01), a longer duration of carbohydrate supplementation (38.9 ± 40.4 vs. 17.8 ± 21.4 days, P < .01), and higher mean C-peptide levels on "critical sample" (1.4 ± 0.9 vs. 0.8 ± 0.5 ng/ml, P < .01). Their insulin levels also tended to be higher (3.5 ± 2.9 vs. 2.2 ± 3.8 µU/ml, P = .07). A stepwise logistic regression model revealed that significant predictors of prolonged HH were maximal GIRs (odds ratio (OR) 1.56, 95%; confidence interval (CI) 1.3-1.88, P < .001) and C-peptide levels (OR 3.57, 95%; CI 1.3-12.1, P = .005).Conclusion: Higher C-peptide levels and higher GIR requirements may serve as clinical tools to identify neonates with transient HH who may benefit from diazoxide treatment.What is Known:• Neonates with transient hyperinsulinism usually do not require treatment beyond glucose supplementation due to its self-limited clinical course, but some may benefit from diazoxide treatment.What is New:• Higher C-peptide levels and higher GIR requirements may serve as clinical tools to identify neonates with transient HH who may benefit from diazoxide treatment.• The incidence of prolonged neonatal HH is higher than the currently accepted figures.

Congenital hyperinsulinism: management and outcome, a single tertiary centre experience.

Hyperinsulinemic hypoglycaemia (HH) is the most frequent cause of persistent hypoglycaemia in neonates and infants. The most severe forms of HH are inherited and referred to as congenital hyperinsulinism (CHI). Diazoxide is the mainstay of treatment, with surgery being an option in appropriate cases. To describe the management and outcome of patients with CHI within our service. Children referred to or attending HH clinic between 2009 and 2017 were identified. Clinical course, genetics and interventions were documented. A total of 39 children were identified, and seven patients with secondary and syndromic HH were excluded. Most were born with an appropriate weight for gestational age (62.5%). Diazoxide was started in all patients; however, 7 did not respond and required octreotide/continuous feeding, with 6/7 requiring surgery. Genetic mutations were detected in 12/32 (37.5%). Hyperinsulinism resolved in conservatively treated patients within 12 months in 11/32 (34.3%) compared to 14/32 (43.7%) requiring more than 12 months of medication. A total of 7 patients underwent pancreatectomy.Conclusion: Although LGA and SGA are risk factors, most babies in our cohort are born AGA. A genetic mutation does not exclude medical remission; long-term conservative treatment of CHI is feasible as surgery does not guarantee complete remission.What is Known:•Congenital hyperinsulinism (CHI) is a clinically and genetically heterogeneous disorder that is the most common cause of permanent hypoglycaemia in infants and children.•Identification of genetic mutations and the use of 18F-DOPA PET scan when feasible lead to better outcomes.What is New:•The study describes clinical criteria, management and outcome of large number of patients with CHI in single tertiary centre.•Conservative treatment is feasible without the need for surgery, with HH resolving in over 30% within 12 months, irrespective of genetic mutation.

Diazoxide-induced pulmonary hypertension in hyperinsulinaemic hypoglycaemia: Recommendations from a multicentre study in the United Kingdom.

OBJECTIVE: Diazoxide is first-line treatment for hyperinsulinaemic hypoglycaemia (HH) but diazoxide-induced pulmonary hypertension (PH) can occur. We aim to characterize the incidence and risk factors of diazoxide-induced PH in a large HH cohort to provide recommendations for anticipating and preventing PH in diazoxide-treated patients with HH. DESIGN AND PATIENTS: Retrospective cohort study involving four UK regional HH centres; review of case notes of HH patients on diazoxide. MEASUREMENTS: The diagnosis of PH was based on clinical and echocardiography evidence. Patient and treatment-related risk factors were analysed for association. RESULTS: Thirteen (6 men) of 177 HH diazoxide-treated patients developed PH, an incidence of 7%. In the PH group, HH was diagnosed at median (range) of 9 (1,180) days, with diazoxide commenced 4 (0,76) days from diagnosis and reaching a maximum dose of 7 (2.5,20) mg/kg/d. The majority (8 of 13 patients) developed PH within 2 weeks of diazoxide. Complete diazoxide withdrawal, but not dose reduction, led to PH resolution at 41 (3,959) days. In three patients, PH continued beyond 12 months. Risk factors for the development of PH included the presence of congenital heart disease (CHD) (P = .008), and total fluid volume exceeding 130 mL/kg/d in the immediate 24 hours preceding diazoxide (P = .019). CONCLUSION: Pulmonary hypertension can occur in 7% of diazoxide-treated HH patients. Risk factors include the presence of congenital heart disease and fluid overload. Recommendations include echocardiography and fluid restriction to 130 mL/kg/d prior to diazoxide treatment and immediate discontinuation of diazoxide if PH develops.

Novel dominant KATP channel mutations in infants with congenital hyperinsulinism: Validation by in vitro expression studies and in vivo carrier phenotyping.

Inactivating mutations in the genes encoding the two subunits of the pancreatic beta-cell KATP channel, ABCC8 and KCNJ11, are the most common finding in children with congenital hyperinsulinism (HI). Interpreting novel missense variants in these genes is problematic, because they can be either dominant or recessive mutations, benign polymorphisms, or diabetes mutations. This report describes six novel missense variants in ABCC8 and KCNJ11 that were identified in 11 probands with congenital HI. One of the three ABCC8 mutations (p.Ala1458Thr) and all three KCNJ11 mutations were associated with responsiveness to diazoxide. Sixteen family members carried the ABCC8 or KCNJ11 mutations; only two had hypoglycemia detected at birth and four others reported symptoms of hypoglycemia. Phenotype testing of seven adult mutation carriers revealed abnormal protein-induced hypoglycemia in all; fasting hypoketotic hypoglycemia was demonstrated in four of the seven. All of six mutations were confirmed to cause dominant pathogenic defects based on in vitro expression studies in COSm6 cells demonstrating normal trafficking, but reduced responses to MgADP and diazoxide. These results indicate a combination of in vitro and in vivo phenotype tests can be used to differentiate dominant from recessive KATP channel HI mutations and personalize management of children with congenital HI.

Harnessing ionic mechanisms to achieve disease modification in neurodegenerative disorders.

Progressive neuronal death is the key pathogenic event leading to clinical symptoms in neurodegenerative disorders (NDDs). Neuroprotective treatments are virtually unavailable, partly because of the marked internal heterogeneity of the mechanisms underlying pathology. Targeted neuroprotection would require deep mechanistic knowledge across the entire aetiological spectrum of each NDD and the development of tailored treatments. Although ideal, this strategy appears challenging, as it would require a degree of characterization of both the disease and the patient that is currently unavailable. The alternate strategy is to search for commonalities across molecularly distinct NDD forms and exploit these for the development of drugs with broad-spectrum efficacy. In this view, mounting evidence points to ionic mechanisms (IMs) as targets with potential therapeutic efficacy across distinct NDD subtypes. The scope of this review is to present clinical and preclinical evidence supporting the link between disruption of IMs and neuronal death in specific NDDs and to critically revise past and ongoing attempts of harnessing IMs for the development of neuroprotective treatments.