Both insulin resistance and reactive oxygen species (ROS) have been reported to play essential pathophysiological roles in cardiovascular diseases, such as hypertension and atherosclerosis. However, ...the mechanistic link between ROS, such as H2O2 and insulin resistance in the vasculature, remains undetermined. Akt, a Ser/Thr kinase, mediates various biological responses induced by insulin. In this study, we examined the effects of H2O2 on Akt activation in the insulin-signaling pathway in vascular smooth muscle cells (VSMCs). In VSMCs, insulin stimulates Akt phosphorylation at Ser473. Pretreatment with H2O2 concentration- and time-dependently inhibited insulin-induced Akt phosphorylation with significant inhibition observed at 50 microM for 10 min. A ROS inducer, diamide, also inhibited insulin-induced Akt phosphorylation. In addition, H2O2 inhibited insulin receptor binding partially and inhibited insulin receptor autophosphorylation almost completely. However, pretreatment with a protein kinase C inhibitor, GF109203X (2 microM), for 30 min did not block the inhibitory effects of H2O2 on insulin-induced Akt phosphorylation, suggesting that protein kinase C is not involved in the inhibition by H2O2. We conclude that ROS inhibit a critical insulin signal transduction component required for Akt activation in VSMCs, suggesting potential cellular mechanisms of insulin resistance, which would require verification in vivo.
ABSTRACT—Fatty acid oxidation (FAO) defects are inborn errors of metabolism clinically associated with cardiomyopathy and sudden infant death syndrome (SIDS). FAO disorders often present in infancy ...with myocardial dysfunction and arrhythmias after exposure to stresses such as fasting, exercise, or intercurrent viral illness. It is uncertain whether the heart, in the absence of stress, is normal. We generated very-long-chain acyl-coenzyme A dehydrogenase (VLCAD)-deficient mice by homologous recombination to define the onset and molecular mechanism of myocardial disease. We found that VLCAD-deficient hearts have microvesicular lipid accumulation, marked mitochondrial proliferation, and demonstrated facilitated induction of polymorphic ventricular tachycardia, without antecedent stress. The expression of acyl-CoA synthase (ACS1), adipophilin, activator protein 2, cytochrome c, and the peroxisome proliferator activated receptor γ coactivator-1 were increased immediately after birth, preceding overt histological lipidosis, whereas ACS1 expression was markedly downregulated in the adult heart. We conclude that mice with VLCAD deficiency have altered expression of a variety of genes in the fatty acid metabolic pathway from birth, reflecting metabolic feedback circuits, with progression to ultrastructural and physiological correlates of the associated human disease in the absence of stress.
1 Division of Cardiology, Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee; 2 Washington University School of Medicine, St. Louis, Missouri; and 3 Division of ...Cardiovascular Medicine, Department of Internal Medicine and Mouse Metabolic Phenotyping Center, Vanderbilt University School of Medicine, Nashville, Tennessee
Submitted 1 August 2005
; accepted in final form 19 September 2005
Mitochondrial very-long-chain acyl-CoA dehydrogenase (VLCAD) deficiency is associated with severe hypoglycemia, cardiac dysfunction, and sudden death in neonates and children. Sudden death is common, but the underlying mechanisms are not fully understood. We report on a mouse model of VLCAD deficiency with a phenotype induced by the stresses of fasting and cold, which includes hypoglycemia, hypothermia, and severe bradycardia. The administration of glucose did not rescue the mice under stress conditions, but rewarming alone consistently led to heart rate recovery. Brown adipose tissue (BAT) from the VLCAD / mice showed elevated levels of the uncoupling protein isoforms and peroxisome proliferator-activated receptor- . Biochemical assessment of the VLCAD / mice BAT showed increased oxygen consumption, attributed to uncoupled respiration in the absence of stress. ADP-stimulated respiration was 23.05 (SD 4.17) and 68.24 (SD 6.3) nmol O 2 ·min 1 ·mg mitochondrial protein 1 for VLCAD +/+ and VLCAD / mice, respectively ( P < 0.001), and carbonyl cyanide p -trifluoromethoxyphenylhydrazone-stimulated respiration was 35.9 (SD 3.6) and 49.3 (SD 9) nmol O 2 ·min 1 ·mg mitochondrial protein 1 for VLCAD +/+ and VLCAD / mice, respectively ( P < 0.20), but these rates were insufficient to protect them in the cold. We conclude that disturbed mitochondrial bioenergetics in BAT is a critical contributing factor for the cold sensitivity in VLCAD deficiency. Our observations provide insights into the possible mechanisms of stress-induced death in human newborns with abnormal fat metabolism and elucidate targeting of specific substrates for particular metabolic needs.
genetics; inborn errors; acyl-coenzyme A dehydrogenase; cardiomyopathy; hypothermia; hypoglycemia; bradycardia
Address for reprint requests and other correspondence: V. Exil, Vanderbilt Children's Hospital, Division of Pediatric Cardiology, 2200 Children's Way, Rm. 5230 DOT, Nashville, TN 37232-9119 (e-mail: vernat.exil{at}vanderbilt.edu )
ABSTRACT—To better understand the intracellular signaling mechanism that causes the association of insulin resistance and hyperlipidemia with cardiovascular diseases, we specifically looked at the ...ability of lysophosphatidylcholine (lysoPC) to inhibit the Akt activation induced by insulin in cultured rat aortic vascular smooth muscle cells. LysoPC inhibited the insulin-induced phosphorylation of Akt at Ser473, and the inhibition was concentration dependent. Phorbol 12-myristate 13-acetate (PMA), a protein kinase C (PKC) activator, inhibited the insulin-induced phosphorylation of Akt. LysoPC stimulated PKC phosphorylation at Ser660, which was inhibited by the PKC inhibitor GF109203X. The PKC-α/β-selective inhibitor Go6976 also blocked the PMA- and lysoPC-induced inhibition of Akt phosphorylation by insulin. PKC-α, but not PKC-β, is expressed in vascular smooth muscle cells, and overexpression of PKC-α, but not PKC-β or PKC-δ, inhibited insulin-induced Akt activation. LysoPC rapidly stimulated PKC-α translocation to the membrane. In contrast, pretreatment with the p42/44 mitogen-activated protein kinase kinase inhibitor PD98059 or the p38 mitogen-activated protein kinase inhibitor SB203580 did not block the lysoPC-induced inhibition of Akt phosphorylation by insulin. In addition, lysoPC inhibited the insulin-induced tyrosine phosphorylation of insulin receptor substrate (IRS)-1 but not that of the insulin receptor β subunit or insulin binding. PMA treatment or PKC-α overexpression also inhibited the tyrosine phosphorylation of IRS-1. From these data, we conclude that lysoPC negatively regulates the insulin signal at the point of IRS-1 through PKC-α in the vasculature, which may explain the association of hyperlipidemia with hyperinsulinemia in cardiovascular diseases.
Mitochondrial very-long-chain acyl-CoA dehydrogenase (VLCAD) deficiency is associated with severe hypoglycemia, cardiac dysfunction, and sudden death in neonates and children. Sudden death is common, ...but the underlying mechanisms are not fully understood. We report on a mouse model of VLCAD deficiency with a phenotype induced by the stresses of fasting and cold, which includes hypoglycemia, hypothermia, and severe bradycardia. The administration of glucose did not rescue the mice under stress conditions, but rewarming alone consistently led to heart rate recovery. Brown adipose tissue (BAT) from the VLCAD mice showed elevated levels of the uncoupling protein isoforms and peroxisome proliferator-activated receptor-{alpha}. Biochemical assessment of the VLCAD mice BAT showed increased oxygen consumption, attributed to uncoupled respiration in the absence of stress. ADP-stimulated respiration was 23.05 (SD 4.17) and 68.24 (SD 6.3) nmol O2 min-1 mg mitochondrial protein-1 for VLCAD+/+ and VLCAD mice, respectively (P < 0.001), and carbonyl cyanide p-trifluoromethoxyphenylhydrazone-stimulated respiration was 35.9 (SD 3.6) and 49.3 (SD 9) nmol O2 min-1 mg mitochondrial protein-1 for VLCAD+/+ and VLCAD mice, respectively (P < 0.20), but these rates were insufficient to protect them in the cold. We conclude that disturbed mitochondrial bioenergetics in BAT is a critical contributing factor for the cold sensitivity in VLCAD deficiency. Our observations provide insights into the possible mechanisms of stress-induced death in human newborns with abnormal fat metabolism and elucidate targeting of specific substrates for particular metabolic needs.PUBLICATION ABSTRACT
To better understand the intracellular signaling mechanism that causes the association of insulin resistance and hyperlipidemia with cardiovascular diseases, we specifically looked at the ability of ...lysophosphatidylcholine (lysoPC) to inhibit the Akt activation induced by insulin in cultured rat aortic vascular smooth muscle cells. LysoPC inhibited the insulin-induced phosphorylation of Akt at Ser473, and the inhibition was concentration dependent. Phorbol 12-myristate 13-acetate (PMA), a protein kinase C (PKC) activator, inhibited the insulin-induced phosphorylation of Akt. LysoPC stimulated PKC phosphorylation at Ser660, which was inhibited by the PKC inhibitor GF109203X. The PKC-alpha/beta-selective inhibitor Go6976 also blocked the PMA- and lysoPC-induced inhibition of Akt phosphorylation by insulin. PKC-alpha, but not PKC-beta, is expressed in vascular smooth muscle cells, and overexpression of PKC-alpha, but not PKC-beta or PKC-delta, inhibited insulin-induced Akt activation. LysoPC rapidly stimulated PKC-alpha translocation to the membrane. In contrast, pretreatment with the p42/44 mitogen-activated protein kinase kinase inhibitor PD98059 or the p38 mitogen-activated protein kinase inhibitor SB203580 did not block the lysoPC-induced inhibition of Akt phosphorylation by insulin. In addition, lysoPC inhibited the insulin-induced tyrosine phosphorylation of insulin receptor substrate (IRS)-1 but not that of the insulin receptor beta subunit or insulin binding. PMA treatment or PKC-alpha overexpression also inhibited the tyrosine phosphorylation of IRS-1. From these data, we conclude that lysoPC negatively regulates the insulin signal at the point of IRS-1 through PKC-alpha in the vasculature, which may explain the association of hyperlipidemia with hyperinsulinemia in cardiovascular diseases.
The coronavirus disease 2019 (COVID-19) has swept the globe and is causing significant morbidity and mortality. Given that the virus is transmitted via droplets, open airway procedures such as ...bronchoscopy pose a significant risk to health-care workers (HCWs). The goal of this guideline was to examine the current evidence on the role of bronchoscopy during the COVID-19 pandemic and the optimal protection of patients and HCWs.
A group of approved panelists developed key clinical questions by using the Population, Intervention, Comparator, and Outcome (PICO) format that addressed specific topics on bronchoscopy related to COVID-19 infection and transmission. MEDLINE (via PubMed) was systematically searched for relevant literature and references were screened for inclusion. Validated evaluation tools were used to assess the quality of studies and to grade the level of evidence to support each recommendation. When evidence did not exist, suggestions were developed based on consensus using the modified Delphi process.
The systematic review and critical analysis of the literature based on six PICO questions resulted in six statements: one evidence-based graded recommendation and 5 ungraded consensus-based statements.
The evidence on the role of bronchoscopy during the COVID-19 pandemic is sparse. To maximize protection of patients and HCWs, bronchoscopy should be used sparingly in the evaluation and management of patients with suspected or confirmed COVID-19 infections. In an area where community transmission of COVID-19 infection is present, bronchoscopy should be deferred for nonurgent indications, and if necessary to perform, HCWs should wear personal protective equipment while performing the procedure even on asymptomatic patients.
While ulceration is one of the most common infantile hemangioma (IH) complications, severe bleeding is a rare consequence, with a paucity of patients reported. We report a 5-month-old girl with a ...very large, mixed, partial segmental IH of the upper chest wall who, despite medical intervention, developed severe ulceration and multiple episodes of life-threatening bleeding that ultimately led to hemorrhagic shock. Experience in our patient and a review of six previous reports shows that severe bleeding is a risk when ulceration extends directly into an arterial feeding vessel that is often visible clinically. Other potential predictors for severe bleeding include large to very large IH size with extension of the tumor into underlying structures, segmental or partial segmental patterning, mixed and bulky morphology, and white discoloration as a sign of impending or worsening ulceration.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Malnutrition, muscle loss, and cachexia are prevalent in cancer and remain key challenges in oncology today. These conditions are frequently underrecognized and undertreated and have devastating ...consequences for patients. Early nutrition screening/assessment and intervention are associated with improved patient outcomes. As a multifaceted disease, cancer requires multimodal care that integrates supportive interventions, specifically nutrition and exercise, to improve nutrient intake, muscle mass, physical functioning, quality of life, and treatment outcomes. An integrated team of healthcare providers that incorporates societies’ recommendations into clinical practice can help achieve the best possible outcomes. A multidisciplinary panel of experts in oncology, nutrition, exercise, and medicine participated in a 2-day virtual roundtable in October 2020 to discuss gaps and opportunities in oncology nutrition, alone and in combination with exercise, relative to current evidence and international societies’ recommendations. The panel recommended five principles to optimize clinical oncology practice: (1) position oncology nutrition at the center of multidisciplinary care; (2) partner with colleagues and administrators to integrate a nutrition care process into the multidisciplinary cancer care approach; (3) screen all patients for malnutrition risk at diagnosis and regularly throughout treatment; (4) combine exercise and nutrition interventions before (e.g., prehabilitation), during, and after treatment as oncology standard of care to optimize nutrition status and muscle mass; and (5) incorporate a patient-centered approach into multidisciplinary care.
Patients with heart failure (HF) display erectile dysfunction (ED). However, the pathophysiology of ED during HF remains poorly investigated.
This study aimed to characterize the aortocaval fistula ...(ACF) rat model associated with HF as a novel experimental model of ED. We have undertaken molecular and functional studies to evaluate the alterations of the nitric oxide (NO) pathway, autonomic nervous system and oxidative stress in the penis.
Male rats were submitted to ACF for HF induction. Intracavernosal pressure in anesthetized rats was evaluated. Concentration-response curves to contractile (phenylephrine) and relaxant agents (sodium nitroprusside; SNP), as well as to electrical field stimulation (EFS), were obtained in the cavernosal smooth muscle (CSM) strips from sham and HF rats. Protein expression of endothelial NO synthase (eNOS) and neuronal NO synthase (nNOS) and phosphodiestarese-5 in CSM were evaluated, as well as NOX2 (gp91phox) and superoxide dismutase (SOD) mRNA expression. SOD activity and thiobarbituric acid reactive substances (TBARs) were also performed in plasma.
HF rats display erectile dysfunction represented by decreased ICP responses compared to sham rats. The neurogenic contractile responses elicited by EFS were greater in CSM from the HF group. Likewise, phenylephrine-induced contractions were greater in CSM from HF rats. Nitrergic response induced by EFS were decreased in the cavernosal tissue, along with lower eNOS, nNOS and phosphodiestarese-5 protein expressions. An increase of NOX2 and SOD mRNA expression in CSM and plasma TBARs of HF group were detected. Plasma SOD activity was decreased in HF rats.
ED in HF rats is associated with decreased NO bioavailability in erectile tissue due to eNOS/nNOS dowregulation and NOX2 upregulation, as well as hypercontractility of the penis. This rat model of ACF could be a useful tool to evaluate the molecular alterations of ED associated with HF.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
PDF
