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JTCVS Open Sep 2023The adenosine triphosphate-sensitive potassium channel opener diazoxide mimics ischemic preconditioning and is cardioprotective. Clarification of diazoxide's site and...
OBJECTIVE
The adenosine triphosphate-sensitive potassium channel opener diazoxide mimics ischemic preconditioning and is cardioprotective. Clarification of diazoxide's site and mechanism of action could lead to targeted pharmacologic therapies for patients undergoing cardiac surgery. Several mitochondrial candidate proteins have been investigated as potential adenosine triphosphate-sensitive potassium channel components. Renal outer medullary potassium (Kir1.1) and sulfonylurea sensitive regulatory subunit 1 have been suggested as subunits of a mitochondrial adenosine triphosphate-sensitive potassium channel. We hypothesized that pharmacologic blockade or genetic deletion (knockout) of renal outer medullary potassium and sensitive regulatory subunit 1 would result in loss of diazoxide cardioprotection in models of global ischemia with cardioplegia.
METHODS
Myocyte volume and contractility were compared after Tyrode's physiologic solution (20 minutes), stress (hyperkalemic cardioplegia ± diazoxide, ± VU591 (Kir1.1 inhibitor), N = 9 to 23 each, 20 min), and Tyrode's (20 minutes). Isolated mouse (wild-type, sensitive regulatory subunit 1 [-/-], and cardiac knockout renal outer medullary potassium) hearts were given cardioplegia ± diazoxide (N = 9-16 each) before global ischemia (90 minutes) and 30 minutes reperfusion. Left ventricular pressures were compared before and after ischemia.
RESULTS
Stress (cardioplegia) was associated with reduced myocyte contractility that was prevented by diazoxide. Isolated myocytes were not responsive to diazoxide in the presence of VU591. In isolated hearts, diazoxide improved left ventricular function after prolonged ischemia compared with cardioplegia alone in wild-type and knockout (sensitive regulatory subunit 1 [-/-] and cardiac knockout renal outer medullary potassium) mice.
CONCLUSIONS
Isolated myocyte and heart models may measure independent and separate actions of diazoxide. By definitive genetic deletion, these data indicate that sensitive regulatory subunit 1 and renal outer medullary potassium are not implicated in cardioprotection by diazoxide.
PubMed: 37808059
DOI: 10.1016/j.xjon.2023.06.004 -
Toxicology Oct 2023Bleomycin (BLM), a frequently employed chemotherapeutic agent, exhibits restricted clinical utility owing to its pulmonary toxicity. Meanwhile, baicalin (BA)-an active...
Bleomycin (BLM), a frequently employed chemotherapeutic agent, exhibits restricted clinical utility owing to its pulmonary toxicity. Meanwhile, baicalin (BA)-an active ingredient extracted from the roots of Scutellaria baicalensis Georgi -has been shown to alleviate BLM-induced pulmonary fibrosis (PF). Hence, the objective of this study was to examine the protective effects of BA in the context of BLM-induced early PF in mice and elucidate the underlying mechanism(s). We established an in vivo BLM (3.5 mg/kg)-induced PF murine model and in vitro BLM (35 μM)-damaged MLE-12 cell model. On Day 14 of treatment, the levels of fibrosis and apoptosis were evaluated in mouse lungs via hydroxyproline analysis, western blotting (COL1A1, TGF-β, Bax, Bcl-2, cleaved caspase-3), and Masson, immunohistochemical (α-SMA, AIF, Cyto C), and TUNEL staining. Additionally, in vitro, apoptosis was assessed in MLE-12 cells exposed to BLM for 24 h using the Annexin V/PI assay and western blotting (Bax, Bcl-2, cleaved caspase-3, AIF, Cyto C). To elucidate the role of the mitochondrial ATP-sensitive potassium channel (mitoKATP) in the protective effect of BA, we utilised diazoxide (DZX)-a mitoKATP agonist-and 5-hydroxydecanoate sodium (5-HD)-a mitoKATP inhibitor. Results revealed the involvement of mitoKATP in the protective effect of BA in BLM-induced PF. More specifically, mitoKATP activation can attenuate BLM-induced PF progression and mitigate alveolar epithelial type II cell death by reducing mitochondrial ROS, maintaining the mitochondrial membrane potential, and impeding the mitochondrial apoptotic pathway. Collectively, the findings offer pharmacological support to use BA for the treatment or prevention of BLM-induced PF and suggest that mitoKATP might serve as an effective therapeutic target for this condition.
Topics: Mice; Animals; Pulmonary Fibrosis; Bleomycin; Caspase 3; bcl-2-Associated X Protein; Signal Transduction; Proto-Oncogene Proteins c-bcl-2
PubMed: 37783230
DOI: 10.1016/j.tox.2023.153638 -
Frontiers in Cardiovascular Medicine 2023[This corrects the article DOI: 10.3389/fcvm.2021.711465.].
[This corrects the article DOI: 10.3389/fcvm.2021.711465.].
PubMed: 37781299
DOI: 10.3389/fcvm.2023.1281995 -
Frontiers in Medicine 2023The Drug Rash with Eosinophilia and Systemic Symptoms (DRESS) syndrome can be potentially life-threatening. The diagnosis is sometimes difficult since the clinical...
The Drug Rash with Eosinophilia and Systemic Symptoms (DRESS) syndrome can be potentially life-threatening. The diagnosis is sometimes difficult since the clinical manifestations may be incomplete or non-specific. Insulinoma is a rare functioning neuroendocrine tumor (NET) of the pancreas. Medical therapy may be needed when surgery is contraindicated, delayed or refused. Diazoxide is widely used to control hypoglycemia in patients with insulinoma. We report a clinical case of an insulinoma in a 85-year-old patient treated with diazoxide with a fatal outcome due to a delayed diagnosis of a DRESS syndrome. This is the first case of DRESS syndrome reported after using diazoxide for insulinoma treatment in our knowledge.
PubMed: 37601782
DOI: 10.3389/fmed.2023.1196041 -
BioRxiv : the Preprint Server For... Aug 2023Pancreatic islets are nutrient sensors that regulate organismal blood glucose homeostasis. Glucagon release from the pancreatic α-cell is important under fasted, fed,...
OBJECTIVE
Pancreatic islets are nutrient sensors that regulate organismal blood glucose homeostasis. Glucagon release from the pancreatic α-cell is important under fasted, fed, and hypoglycemic conditions, yet metabolic regulation of α-cells remains poorly understood. Here, we identified a previously unexplored role for physiological levels of leucine, which is classically regarded as a β-cell fuel, in the intrinsic regulation of α-cell glucagon release.
METHODS
GcgCre:CAMPER and GcgCre:GCaMP6s mice were generated to perform dynamic, high-throughput functional measurements of α-cell cAMP and Ca within the intact islet. Islet perifusion assays were used for simultaneous, time-resolved measurements of glucagon and insulin release from mouse and human islets. The effects of leucine were compared with glucose and the mitochondrial fuels 2-aminobicyclo(2,2,1)heptane-2-carboxylic acid (BCH, non-metabolized leucine analog that activates glutamate dehydrogenase), α-ketoisocaproate (KIC, leucine metabolite), and methyl-succinate (complex II fuel). CYN154806 (Sstr2 antagonist), diazoxide (K activator, which prevents Ca-dependent exocytosis from α, β, and δ-cells), and dispersed α-cells were used to inhibit islet paracrine signaling and identify α-cell intrinsic effects.
RESULTS
Mimicking the effect of glucose, leucine strongly suppressed amino acid-stimulated glucagon secretion. Mechanistically, leucine dose-dependently reduced α-cell cAMP at physiological concentrations, with an IC of 57, 440, and 1162 μM at 2, 6, and 10 mM glucose, without affecting α-cell Ca. Leucine also reduced α-cell cAMP in islets treated with Sstr2 antagonist or diazoxide, as well as dispersed α-cells, indicating an α-cell intrinsic effect. The effect of leucine was matched by KIC and the glutamate dehydrogenase activator BCH, but not methyl-succinate, indicating a dependence on mitochondrial anaplerosis. Glucose, which stimulates anaplerosis via pyruvate carboxylase, had the same suppressive effect on α-cell cAMP but with lower potency. Similarly to mouse islets, leucine suppressed glucagon secretion from human islets under hypoglycemic conditions.
CONCLUSIONS
These findings highlight an important role for physiological levels of leucine in the metabolic regulation of α-cell cAMP and glucagon secretion. Leucine functions primarily through an α-cell intrinsic effect that is dependent on glutamate dehydrogenase, in addition to the well-established α-cell regulation by β/δ-cell paracrine signaling. Our results suggest that mitochondrial anaplerosis-cataplerosis facilitates the glucagonostatic effect of both leucine and glucose, which cooperatively suppress α-cell tone by reducing cAMP.
PubMed: 37577685
DOI: 10.1101/2023.07.31.551113 -
Reviews in Endocrine & Metabolic... Dec 2023The initial step for the differential diagnosis of hypoglycemia is to determine whether it is hyperinsulinemic or non hyperinsulinemic. Existing literature discusses... (Review)
Review
The initial step for the differential diagnosis of hypoglycemia is to determine whether it is hyperinsulinemic or non hyperinsulinemic. Existing literature discusses drug-related hypoglycemia, but it misses a focus on drug-induced hyperinsulinemic hypoglycemia (DHH). Here we reviewed the association existing between drugs and hyperinsulinemic hypoglycemia. We primarily selected on the main electronic databases (MEDLINE, EMBASE, Web of Science, and SCOPUS) the reviews on drug-induced hypoglycemia. Among the drugs listed in the reviews, we selected the ones linked to an increase in insulin secretion. For the drugs missing a clear association with insulin secretion, we investigated the putative mechanism underlying hypoglycemia referring to the original papers. Our review provides a list of the most common agents associated with hyperinsulinemic hypoglycemia (HH), in order to facilitate both the recognition and the prevention of DHH. We also collected data about the responsiveness of DHH to diazoxide or octreotide.
Topics: Humans; Hypoglycemia; Hyperinsulinism; Diazoxide; Insulin Secretion
PubMed: 37552352
DOI: 10.1007/s11154-023-09828-y -
AACE Clinical Case Reports 2023To illustrate an unusual case of type 2 diabetes mellitus (T2DM) developing many years after the diagnosis of hyperinsulinism hyperammonemia (HI/HA) syndrome.
BACKGROUND/OBJECTIVE
To illustrate an unusual case of type 2 diabetes mellitus (T2DM) developing many years after the diagnosis of hyperinsulinism hyperammonemia (HI/HA) syndrome.
CASE REPORT
This article reports about a 36-year-old female with a history of congenital hyperinsulinism due to HI/HA syndrome, which was diagnosed in infancy. The patient presented with hypoglycemia and seizures as an infant and was treated with diazoxide and a low-protein diet for many years with reduction in her hypoglycemic events. She subsequently developed T2DM >30 years later. Genetic analysis was positive for a glutamate dehydrogenase 1 gene () alteration. She was treated with metformin and a glucagon-like peptide 1 agonist, with significant improvement in her blood glucose control and weight loss.
DISCUSSION
HI/HA syndrome is a rare genetic syndrome that manifests in childhood with signs and symptoms of hypoglycemia and neurologic symptoms. This is the first case reported in the literature of a patient with HI/HA syndrome due to a alteration who developed T2DM much later in life. Patients with this disorder usually have recurrent hypoglycemia and require long-term medical therapy or very occasionally may have a resolution. She had class 3 obesity and evidence of insulin resistance, which likely contributed to her risk of diabetes.
CONCLUSION
This is a rare case of T2DM presenting in a patient with HI/HA syndrome. This should be considered a possible outcome in patients with this disorder, especially in the presence of obesity.
PubMed: 37520762
DOI: 10.1016/j.aace.2023.04.011 -
Frontiers in Neurology 2023One of the most prevalent types of epilepsy is temporal lobe epilepsy (TLE), which has unknown etiological factors and drug resistance. The detailed mechanisms...
One of the most prevalent types of epilepsy is temporal lobe epilepsy (TLE), which has unknown etiological factors and drug resistance. The detailed mechanisms underlying potassium channels in human TLE have not yet been elucidated. Hence, this study aimed to mine potassium channel genes linked to TLE using a bioinformatic approach. The results found that Four key TLE-related potassium channel genes (TERKPCGs) were identified: potassium voltage-gated channel subfamily E member () 1, , potassium inwardly rectifying channel, subfamily J, member 11 (), and . A protein-protein interaction (PPI) network was constructed to analyze the relationship between TERKPCGs and other key module genes. The results of gene set enrichment analysis (GSEA) for a single gene indicated that the four TERKPCGs were highly linked to the cation channel, potassium channel, respiratory chain, and oxidative phosphorylation. The mRNA-TF network was established using four mRNAs and 113 predicted transcription factors. A ceRNA network containing seven miRNAs, two mRNAs, and 244 lncRNAs was constructed based on the TERKPCGs. Three common small-molecule drugs (enflurane, promethazine, and miconazole) target , and . Ten small-molecule drugs (glimepiride, diazoxide, levosimendan, and thiamylal et al.) were retrieved for . Compared to normal mice, the expression of , , , and was downregulated in the brain tissue of the epilepsy mouse model at both the transcriptional and translational levels, which was consistent with the trend of human data from the public database. The results indicated that key potassium channel genes linked to TLE were identified based on bioinformatics analysis to investigate the potential significance of potassium channel genes in the development and treatment of TLE.
PubMed: 37483435
DOI: 10.3389/fneur.2023.1175007 -
Hormone Research in Paediatrics 2024Hyperinsulinism (HI) due to dysregulation of pancreatic beta-cell insulin secretion is the most common and most severe cause of persistent hypoglycemia in infants and... (Review)
Review
BACKGROUND
Hyperinsulinism (HI) due to dysregulation of pancreatic beta-cell insulin secretion is the most common and most severe cause of persistent hypoglycemia in infants and children. In the 65 years since HI in children was first described, there has been a dramatic advancement in the diagnostic tools available, including new genetic techniques and novel radiologic imaging for focal HI; however, there have been almost no new therapeutic modalities since the development of diazoxide.
SUMMARY
Recent advances in neonatal research and genetics have improved our understanding of the pathophysiology of both transient and persistent forms of neonatal hyperinsulinism. Rapid turnaround of genetic test results combined with advanced radiologic imaging can permit identification and localization of surgically-curable focal lesions in a large proportion of children with congenital forms of HI, but are only available in certain centers in "developed" countries. Diazoxide, the only drug currently approved for treating HI, was recently designated as an "essential medicine" by the World Health Organization but has been approved in only 16% of Latin American countries and remains unavailable in many under-developed areas of the world. Novel treatments for HI are emerging, but they await completion of safety and efficacy trials before being considered for clinical use.
KEY MESSAGES
This international consensus statement on diagnosis and management of HI was developed in order to assist specialists, general pediatricians, and neonatologists in early recognition and treatment of HI with the ultimate aim of reducing the prevalence of brain injury caused by hypoglycemia. A previous statement on diagnosis and management of HI in Japan was published in 2017. The current document provides an updated guideline for management of infants and children with HI and includes potential accommodations for less-developed regions of the world where resources may be limited.
Topics: Humans; Infant, Newborn; Congenital Hyperinsulinism; Diazoxide; Infant; Female; Male; Practice Guidelines as Topic; Child
PubMed: 37454648
DOI: 10.1159/000531766 -
Frontiers in Endocrinology 2023Given that reports on severe diazoxide (DZX) toxicity are increasing, we aimed to understand if the short-term clinical outcomes of small-for-gestational-age (SGA)... (Observational Study)
Observational Study
INTRODUCTION
Given that reports on severe diazoxide (DZX) toxicity are increasing, we aimed to understand if the short-term clinical outcomes of small-for-gestational-age (SGA) infants with hyperinsulinemic hypoglycemia (HH) managed primarily by supportive care, termed watchful waiting (WW), are different from those treated with DZX.
METHOD
A real-life observational cohort study was conducted from 1 September 2014 to 30 September 2020. The WW or DZX management decision was based on clinical and biochemical criteria. We compared central line duration (CLD), postnatal length of stay (LOS), and total intervention days (TIDs) among SGA-HH infants treated with DZX versus those on a WW approach. Fasting studies determined the resolution of HH.
RESULT
Among 71,836 live births, 11,493 were SGA, and 51 SGA infants had HH. There were 26 and 25 SGA-HH infants in the DZX and WW groups, respectively. Clinical and biochemical parameters were similar between groups. The median day of DZX initiation was day 10 of life (range 4-32), at a median dose of 4 mg/kg/day (range 3-10). All infants underwent fasting studies. Median CLD [DZX, 15 days (6-27) vs. WW, 14 days (5-31), P = 0.582] and postnatal LOS [DZX, 23 days (11-49) vs. WW, 22 days (8-61), P = 0.915] were comparable. Median TID was >3-fold longer in the DZX than the WW group [62.5 days (9-198) vs. 16 days (6-27), P < 0.001].
CONCLUSION
CLD and LOS are comparable between WW and DZX groups. Since fasting studies determine the resolution of HH, physicians should be aware that clinical intervention of DZX-treated SGA-HH patients extends beyond the initial LOS.
Topics: Humans; Infant; Watchful Waiting; Fasting; Awareness; Cognition; Diazoxide; Hyperinsulinism; Hypoglycemia
PubMed: 37435482
DOI: 10.3389/fendo.2023.1163591