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1.
bioRxiv ; 2024 Aug 19.
Artículo en Inglés | MEDLINE | ID: mdl-39229013

RESUMEN

Microvascular insulin delivery to myocytes is rate limiting for the onset of insulin-stimulated muscle glucose uptake. The structural integrity of capillaries of the microvasculature is regulated, in part, by a family of transmembrane adhesion receptors known as integrins, which are composed of an α and ß subunit. The integrin ß1 (itgß1) subunit is highly expressed in endothelial cells (EC). EC itgß1 is necessary for the formation of capillary networks during embryonic during development and its knockdown in adult mice blunts the reactive hyperemia that manifests during ischemia reperfusion. In this study we investigated the contribution of skeletal muscle EC itgß1 in microcirculatory function and glucose uptake. We hypothesized that loss of EC itgß1 would impair microvascular hemodynamics and glucose uptake during insulin stimulation, creating 'delivery'-mediated insulin resistance. An itgß1 knockdown mouse model was developed to avoid lethality of embryonic gene knockout and the deteriorating health resulting from early post-natal inducible gene deletion. We found that mice with (itgß1fl/flSCLcre) and without (itgß1fl/fl) inducible stem cell leukemia cre recombinase (SLCcre) expression at 10 days post cre induction have comparable exercise tolerance and pulmonary and cardiac functions. We quantified microcirculatory hemodynamics using intravital microscopy and the ability of mice to respond to the high metabolic demands of insulin-stimulated muscle using a hyperinsulinemic-euglycemia clamp. We show that itgß1fl/flSCLcre mice compared to itgß1fl/fl littermates have, i) deficits in capillary flow rate, flow heterogeneity, and capillary density; ii) impaired insulin-stimulated glucose uptake despite sufficient transcapillary insulin efflux; and iii) reduced insulin-stimulated glucose uptake due to perfusion-limited glucose delivery. Thus, EC itgß1 is necessary for microcirculatory function and to meet the metabolic challenge of insulin stimulation.

2.
bioRxiv ; 2024 Sep 22.
Artículo en Inglés | MEDLINE | ID: mdl-39345415

RESUMEN

Impaired microvascular function is a hallmark of pre-diabetes. With development of atherosclerosis this impaired microvascular function can result in diminished capacity for ambulation and is a risk factor for Type 2 Diabetes. Dynamic changes in vascular tone are determined, in large part, by the eNOS/NO/cGMP axis. We used gain of function of the eNOS/NO/cGMP axis in diet-induced obese (DIO) mice and reduced function in lean mice to test the hypothesis that functionality of this vascular control mechanism parallels the benefits of an exercise training regimen. DIO mice have lower exercise capacity than lean mice and were used for pharmacological gain of function. The PDE-5a inhibitor - sildenafil - increases cGMP and was administered to DIO mice daily. In sedentary mice, we find that sildenafil does not improve exercise capacity. In contrast, it amplifies the microcirculatory effects of exercise training. Sildenafil synergizes with exercise training to improve performance during an incremental exercise test. Improved exercise performance was accompanied by increased skeletal muscle capillary flow velocity and capillary density measured via intravital microscopy. Loss of function was tested in lean mice hemizygous for endothelial cell (EC) specific eNOS creating an EC-eNOS knockdown (KD). EC-eNOS KD decreases capillary density and exercise tolerance in sedentary mice; however, it did not prevent exercise-training induced improvements in endurance capacity. These data show that 1) increasing cGMP with sildenafil enhances microcirculatory function and exercise work tolerance that results from training; 2) eNOS KD does not prevent the microcirculatory or improvements in exercise tolerance with training. PDE-5a inhibitors combined with physical exercise are a potential mechanism for improving ambulation in patients with circulatory limitations.

4.
J Am Heart Assoc ; 13(16): e030775, 2024 Aug 20.
Artículo en Inglés | MEDLINE | ID: mdl-39119951

RESUMEN

BACKGROUND: Obesity is associated with resistance to the metabolic (glucose uptake) and vascular (nitric-oxide mediated dilation and microvascular recruitment) actions of insulin. These vascular effects contribute to insulin sensitivity by increasing tissue delivery of glucose. Studies by us and others suggest that sympathetic activation contributes to insulin resistance to glucose uptake. Here we tested the hypothesis that sympathetic activation contributes to impaired insulin-mediated vasodilation in adult subjects with obesity. METHODS AND RESULTS: In a randomized crossover study, we used a euglycemic hyperinsulinemic clamp in 12 subjects with obesity to induce forearm arterial vasodilation (forearm blood flow) and microvascular recruitment (contrast-enhanced ultrasonography) during an intrabrachial infusion of saline (control) or phentolamine (sympathetic blockade). Insulin increased forearm blood flow on both study days (from 2.21±1.22 to 4.89±4.21 mL/100 mL per min, P=0.003 and from 2.42±0.89 to 7.19±3.35 mL/100 mL per min, P=0.002 for the intact and blocked day, respectively). Sympathetic blockade with phentolamine resulted in a significantly greater increase in microvascular flow velocity (∆microvascular flow velocity: 0.23±0.65 versus 2.51±3.01 arbitrary intensity units (AIU/s) for saline and phentolamine respectively, P=0.005), microvascular blood volume (∆microvascular blood volume: 1.69±2.45 versus 3.76±2.93 AIU, respectively, P=0.05), and microvascular blood flow (∆microvascular blood flow: 0.28±0.653 versus 2.51±3.01 AIU2/s, respectively, P=0.0161). To evaluate if this effect was not due to nonspecific vasodilation, we replicated the study in 6 subjects with obesity comparing intrabrachial infusion of phentolamine to sodium nitroprusside. At doses that produced similar increases in forearm blood flow, insulin-induced changes in microvascular flow velocity were greater during phentolamine than sodium nitroprusside (%microvascular flow velocity=58% versus 29%, respectively, P=0.031). CONCLUSIONS: We conclude that sympathetic activation impairs insulin-mediated microvascular recruitment in adult subjects with obesity.


Asunto(s)
Estudios Cruzados , Antebrazo , Insulina , Microcirculación , Obesidad , Fentolamina , Flujo Sanguíneo Regional , Sistema Nervioso Simpático , Vasodilatación , Humanos , Antebrazo/irrigación sanguínea , Masculino , Fentolamina/farmacología , Femenino , Obesidad/fisiopatología , Vasodilatación/efectos de los fármacos , Vasodilatación/fisiología , Adulto , Sistema Nervioso Simpático/fisiopatología , Sistema Nervioso Simpático/efectos de los fármacos , Flujo Sanguíneo Regional/efectos de los fármacos , Microcirculación/efectos de los fármacos , Velocidad del Flujo Sanguíneo , Persona de Mediana Edad , Técnica de Clampeo de la Glucosa , Resistencia a la Insulina , Bloqueo Nervioso Autónomo/métodos
5.
Mamm Genome ; 2024 Aug 27.
Artículo en Inglés | MEDLINE | ID: mdl-39191872

RESUMEN

The Mouse Metabolic Phenotyping Center (MMPC)Live Program was established in 2023 by the National Institute for Diabetes, Digestive and Kidney Diseases (NIDDK) at the National Institutes of Health (NIH) to advance biomedical research by providing the scientific community with standardized, high quality phenotyping services for mouse models of diabetes and obesity. Emerging as the next iteration of the MMPC Program which served the biomedical research community for 20 years (2001-2021), MMPCLive is designed as an outwardly-facing consortium of service cores that collaborate to provide reduced-cost consultation and metabolic, physiologic, and behavioral phenotyping tests on live mice for U.S. biomedical researchers. Four MMPCLive Centers located at universities around the country perform complex and often unique procedures in vivo on a fee for service basis, typically on mice shipped from the client or directly from a repository or vendor. Current areas of expertise include energy balance and body composition, insulin action and secretion, whole body carbohydrate and lipid metabolism, cardiovascular and renal function, food intake and behavior, microbiome and xenometabolism, and metabolic pathway kinetics. Additionally, an opportunity arose to reduce barriers to access and expand the diversity of the biomedical research workforce by establishing the VIBRANT Program. Directed at researchers historically underrepresented in the biomedical sciences, VIBRANT-eligible investigators have access to testing services, travel and career development awards, expert advice and experimental design consultation, and short internships to learn test technologies. Data derived from experiments run by the Centers belongs to the researchers submitting mice for testing which can be made publicly available and accessible from the MMPCLive database following publication. In addition to services, MMPCLive staff provide expertise and advice to researchers, develop and refine test protocols, engage in outreach activities, publish scientific and technical papers, and conduct educational workshops and training sessions to aid researchers in unraveling the heterogeneity of diabetes and obesity.

6.
Mol Metab ; 86: 101970, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-38908792

RESUMEN

OBJECTIVE: Obesity increases deposition of extracellular matrix (ECM) components of cardiac tissue. Since obesity aggregates with insulin resistance and heart disease, it is imperative to determine whether the increased ECM deposition contributes to this disease cluster. The hypotheses tested in this study were that in cardiac tissue of obese mice i) increased deposition of ECM components (collagens and hyaluronan) contributes to cardiac insulin resistance and that a reduction in these components improves cardiac insulin action and ii) reducing excess collagens and hyaluronan mitigates obesity-associated cardiac dysfunction. METHODS: Genetic and pharmacological approaches that manipulated collagen and hyaluronan contents were employed in obese C57BL/6 mice fed a high fat (HF) diet. Cardiac insulin sensitivity was measured by hyperinsulinemic-euglycemic clamp and cardiac function was measured by pressure-volume loop analysis in vivo. RESULTS: We demonstrated a tight association between increased ECM deposition with cardiac insulin resistance. Increased collagen deposition by genetic deletion of matrix metalloproteinase 9 (MMP9) exacerbated cardiac insulin resistance and pirfenidone, a clinically available anti-fibrotic medication which inhibits collagen expression, improved cardiac insulin resistance in obese mice. Furthermore, decreased hyaluronan deposition by treatment with PEGylated human recombinant hyaluronidase PH20 (PEGPH20) improved cardiac insulin resistance in obese mice. These relationships corresponded to functional changes in the heart. Both PEGPH20 and pirfenidone treatment in obese mice ameliorated HF diet-induced abnormal myocardial remodelling. CONCLUSION: Our results provide important new insights into the role of ECM deposition in the pathogenesis of cardiac insulin resistance and associated dysfunction in obesity of distinct mouse models. These findings support the novel therapeutic potential of targeting early cardiac ECM abnormalities in the prevention and treatment of obesity-related cardiovascular complications.


Asunto(s)
Dieta Alta en Grasa , Matriz Extracelular , Ácido Hialurónico , Resistencia a la Insulina , Ratones Endogámicos C57BL , Miocardio , Obesidad , Animales , Matriz Extracelular/metabolismo , Ratones , Obesidad/metabolismo , Dieta Alta en Grasa/efectos adversos , Masculino , Ácido Hialurónico/metabolismo , Miocardio/metabolismo , Remodelación Ventricular , Ratones Obesos , Colágeno/metabolismo , Metaloproteinasa 9 de la Matriz/metabolismo , Hialuronoglucosaminidasa/metabolismo
8.
Diabetes ; 73(8): 1229-1243, 2024 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-38743615

RESUMEN

Cytochrome P450 epoxygenase Cyp2c44, a murine epoxyeicosatrienoic acid (EET)-producing enzyme, promotes insulin sensitivity, and Cyp2c44-/- mice show hepatic insulin resistance. Because insulin resistance leads to hepatic lipid accumulation and hyperlipidemia, we hypothesized that Cyp2c44 regulates hepatic lipid metabolism. Standard chow diet (SCD)-fed male Cyp2c44-/- mice had significantly decreased EET levels and increased hepatic and plasma lipid levels compared with wild-type mice. We showed increased hepatic plasma membrane localization of the FA transporter 2 (FATP2) and total unsaturated fatty acids and diacylglycerol (DAG) levels. Cyp2c44-/- mice had impaired glucose tolerance and increased hepatic plasma membrane-associated PKCδ and phosphorylated IRS-1, two negative regulators of insulin signaling. Surprisingly, SCD and high-fat diet (HFD)-fed Cyp2c44-/- mice had similar glucose tolerance and hepatic plasma membrane PKCδ levels, suggesting that SCD-fed Cyp2c44-/- mice have reached their maximal glucose intolerance. Inhibition of PKCδ resulted in decreased IRS-1 serine phosphorylation and improved insulin-mediated signaling in Cyp2c44-/- hepatocytes. Finally, Cyp2c44-/- HFD-fed mice treated with the analog EET-A showed decreased hepatic plasma membrane FATP2 and PCKδ levels with improved glucose tolerance and insulin signaling. In conclusion, loss of Cyp2c44 with concomitant decreased EET levels leads to increased hepatic FATP2 plasma membrane localization, DAG accumulation, and PKCδ-mediated attenuation of insulin signaling. Thus, Cyp2c44 acts as a regulator of lipid metabolism by linking it to insulin signaling.


Asunto(s)
Familia 2 del Citocromo P450 , Diglicéridos , Insulina , Metabolismo de los Lípidos , Hígado , Ratones Noqueados , Proteína Quinasa C-delta , Transducción de Señal , Animales , Masculino , Ratones , Sistema Enzimático del Citocromo P-450/metabolismo , Sistema Enzimático del Citocromo P-450/genética , Familia 2 del Citocromo P450/metabolismo , Familia 2 del Citocromo P450/genética , Dieta Alta en Grasa , Diglicéridos/metabolismo , Epóxido Hidrolasas , Insulina/metabolismo , Resistencia a la Insulina/fisiología , Metabolismo de los Lípidos/fisiología , Hígado/metabolismo , Ratones Endogámicos C57BL , Proteína Quinasa C-delta/metabolismo , Proteína Quinasa C-delta/genética , Transducción de Señal/fisiología
9.
J Lipid Res ; 65(6): 100558, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38729350

RESUMEN

Metabolic dysfunction-associated steatotic liver disease is the most common form of liver disease and poses significant health risks to patients who progress to metabolic dysfunction-associated steatohepatitis. Fatty acid overload alters endoplasmic reticulum (ER) calcium stores and induces mitochondrial oxidative stress in hepatocytes, leading to hepatocellular inflammation and apoptosis. Obese mice have impaired liver sarco/ER Ca2+-ATPase (SERCA) function, which normally maintains intracellular calcium homeostasis by transporting Ca2+ ions from the cytoplasm to the ER. We hypothesized that restoration of SERCA activity would improve diet-induced steatohepatitis in mice by limiting ER stress and mitochondrial dysfunction. WT and melanocortin-4 receptor KO (Mc4r-/-) mice were placed on either chow or Western diet (WD) for 8 weeks. Half of the WD-fed mice were administered CDN1163 to activate SERCA, which reduced liver fibrosis and inflammation. SERCA activation also restored glucose tolerance and insulin sensitivity, improved histological markers of metabolic dysfunction-associated steatohepatitis, increased expression of antioxidant enzymes, and decreased expression of oxidative stress and ER stress genes. CDN1163 decreased hepatic citric acid cycle flux and liver pyruvate cycling, enhanced expression of mitochondrial respiratory genes, and shifted hepatocellular [NADH]/[NAD+] and [NADPH]/[NADP+] ratios to a less oxidized state, which was associated with elevated PUFA content of liver lipids. In sum, the data demonstrate that pharmacological SERCA activation limits metabolic dysfunction-associated steatotic liver disease progression and prevents metabolic dysfunction induced by WD feeding in mice.


Asunto(s)
Hígado , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico , Animales , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/metabolismo , Ratones , Hígado/metabolismo , Hígado/patología , Masculino , Hígado Graso/metabolismo , Hígado Graso/patología , Estrés del Retículo Endoplásmico , Ratones Endogámicos C57BL , Estrés Oxidativo/efectos de los fármacos , Dieta Occidental/efectos adversos , Ratones Noqueados
10.
JCI Insight ; 9(6)2024 02 22.
Artículo en Inglés | MEDLINE | ID: mdl-38516886

RESUMEN

Kidney tubules use fatty acid oxidation (FAO) to support their high energetic requirements. Carnitine palmitoyltransferase 1A (CPT1A) is the rate-limiting enzyme for FAO, and it is necessary to transport long-chain fatty acids into mitochondria. To define the role of tubular CPT1A in aging and injury, we generated mice with tubule-specific deletion of Cpt1a (Cpt1aCKO mice), and the mice were either aged for 2 years or injured by aristolochic acid or unilateral ureteral obstruction. Surprisingly, Cpt1aCKO mice had no significant differences in kidney function or fibrosis compared with wild-type mice after aging or chronic injury. Primary tubule cells from aged Cpt1aCKO mice had a modest decrease in palmitate oxidation but retained the ability to metabolize long-chain fatty acids. Very-long-chain fatty acids, exclusively oxidized by peroxisomes, were reduced in kidneys lacking tubular CPT1A, consistent with increased peroxisomal activity. Single-nuclear RNA-Seq showed significantly increased expression of peroxisomal FAO enzymes in proximal tubules of mice lacking tubular CPT1A. These data suggest that peroxisomal FAO may compensate in the absence of CPT1A, and future genetic studies are needed to confirm the role of peroxisomal ß-oxidation when mitochondrial FAO is impaired.


Asunto(s)
Carnitina O-Palmitoiltransferasa , Riñón , Animales , Ratones , Envejecimiento/genética , Carnitina O-Palmitoiltransferasa/genética , Carnitina O-Palmitoiltransferasa/metabolismo , Ácidos Grasos/metabolismo , Riñón/metabolismo , Riñón/patología , Túbulos Renales/metabolismo
11.
Mol Metab ; 81: 101901, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38354854

RESUMEN

Mammals are protected from changes in environmental temperature by altering energetic processes that modify heat production. Insulin is the dominant stimulus of glucose uptake and metabolism, which are fundamental for thermogenic processes. The purpose of this work was to determine the interaction of ambient temperature induced changes in energy expenditure (EE) on the insulin sensitivity of glucose fluxes. Short-term and adaptive responses to thermoneutral temperature (TN, ∼28 °C) and room (laboratory) temperature (RT, ∼22 °C) were studied in mice. This range of temperature does not cause detectable changes in circulating catecholamines or shivering and postabsorptive glucose homeostasis is maintained. We tested the hypothesis that a decrease in EE that occurs with TN causes insulin resistance and that this reduction in insulin action and EE is reversed upon short term (<12h) transition to RT. Insulin-stimulated glucose disposal (Rd) and tissue-specific glucose metabolic index were assessed combining isotopic tracers with hyperinsulinemic-euglycemic clamps. EE and insulin-stimulated Rd are both decreased (∼50%) in TN-adapted vs RT-adapted mice. When RT-adapted mice are switched to TN, EE rapidly decreases and Rd is reduced by ∼50%. TN-adapted mice switched to RT exhibit a rapid increase in EE, but whole-body insulin-stimulated Rd remains at the low rates of TN-adapted mice. In contrast, whole body glycolytic flux rose with EE. This higher EE occurs without increasing glucose uptake from the blood, but rather by diverting glucose from glucose storage to glycolysis. In addition to adaptations in insulin action, 'insulin-independent' glucose uptake in brown fat is exquisitely sensitive to thermoregulation. These results show that insulin action adjusts to non-stressful changes in ambient temperature to contribute to the support of body temperature homeostasis without compromising glucose homeostasis.


Asunto(s)
Resistencia a la Insulina , Insulina , Ratones , Animales , Insulina/metabolismo , Regulación de la Temperatura Corporal , Glucosa/metabolismo , Metabolismo Energético/fisiología , Insulina Regular Humana/metabolismo , Mamíferos/metabolismo
12.
medRxiv ; 2024 Feb 18.
Artículo en Inglés | MEDLINE | ID: mdl-38405702

RESUMEN

Dysfunction of endothelial insulin delivery to muscle associates with insulin resistance. CD36, a fatty acid transporter and modulator of insulin signaling is abundant in endothelial cells, especially in capillaries. Humans with inherited 50% reduction in CD36 expression have endothelial dysfunction but whether it is associated with insulin resistance is unclear. Using hyperinsulinemic/euglycemic clamps in Cd36-/- and wildtype mice, and in 50% CD36 deficient humans and matched controls we found that Cd36-/- mice have enhanced systemic glucose disposal despite unaltered transendothelial insulin transfer and reductions in microvascular perfusion and blood vessel compliance. Partially CD36 deficient humans also have better glucose disposal than controls with no capillary recruitment by insulin. CD36 knockdown in primary human-derived microvascular cells impairs insulin action on AKT, endothelial nitric oxide synthase, and nitric oxide release. Thus, insulin resistance of microvascular function in CD36 deficiency paradoxically associates with increased glucose utilization, likely through a remodeling of muscle gene expression.

13.
Prenat Diagn ; 44(2): 180-186, 2024 02.
Artículo en Inglés | MEDLINE | ID: mdl-38069681

RESUMEN

OBJECTIVE: Risks and benefits of experimental fetal therapies can remain uncertain after initial clinical studies, especially long-term effects. Nevertheless, pregnant individuals may request them, hoping to benefit their future child. Guidance about offering experimental fetal therapies outside research (as "innovative therapy") is limited, despite their ethical complexity. We propose points for clinicians and reviewers to consider when deciding whether and how to offer experimental fetal therapies as innovative therapies after initial clinical studies. METHOD: We used conceptual analysis and a current case to develop points for consideration, grounded in broader debates on innovative therapy and the unique challenges associated with experimental fetal therapies. RESULTS: Clinicians should evaluate whether offering experimental fetal therapies as innovative therapy is appropriate for a pregnant individual and their fetus. The anticipated risk-benefit ratio for the fetus should be favorable. For the pregnant individual, risks may outweigh benefits, within reasonable limits. Medical resources should be sufficient to ensure appropriate care. Clinicians should support pregnant individuals in making informed choices. Clinicians offering innovative therapies with more than minimal risk should collect and report data on outcomes. Independent review should take place. CONCLUSION: Considering these points may advance the interests of fetuses, future children, and their families.


Asunto(s)
Terapias Fetales , Atención Prenatal , Embarazo , Femenino , Niño , Humanos , Feto , Medición de Riesgo , Terapias en Investigación
14.
Am J Physiol Endocrinol Metab ; 326(1): E14-E28, 2024 01 01.
Artículo en Inglés | MEDLINE | ID: mdl-37938177

RESUMEN

Regular exercise elicits adaptations in glucose and lipid metabolism that allow the body to meet energy demands of subsequent exercise bouts more effectively and mitigate metabolic diseases including fatty liver. Energy discharged during the acute exercise bouts that comprise exercise training may be a catalyst for liver adaptations. During acute exercise, liver glycogenolysis and gluconeogenesis are accelerated to supply glucose to working muscle. Lower liver energy state imposed by gluconeogenesis and related pathways activates AMP-activated protein kinase (AMPK), which conserves ATP partly by promoting lipid oxidation. This study tested the hypothesis that AMPK is necessary for liver glucose and lipid adaptations to training. Liver-specific AMPKα1α2 knockout (AMPKα1α2fl/fl+AlbCre) mice and littermate controls (AMPKα1α2fl/fl) completed sedentary and exercise training protocols. Liver nutrient fluxes were quantified at rest or during acute exercise following training. Liver metabolites and molecular regulators of metabolism were assessed. Training increased liver glycogen in AMPKα1α2fl/fl mice, but not in AMPKα1α2fl/fl+AlbCre mice. The inability to increase glycogen led to lower glycogenolysis, glucose production, and circulating glucose during acute exercise in trained AMPKα1α2fl/fl+AlbCre mice. Deletion of AMPKα1α2 attenuated training-induced declines in liver diacylglycerides. In particular, training lowered the concentration of unsaturated and elongated fatty acids comprising diacylglycerides in AMPKα1α2fl/fl mice, but not in AMPKα1α2fl/fl+AlbCre mice. Training increased liver triacylglycerides and the desaturation and elongation of fatty acids in triacylglycerides of AMPKα1α2fl/fl+AlbCre mice. These lipid responses were independent of differences in tricarboxylic acid cycle fluxes. In conclusion, AMPK is required for liver training adaptations that are critical to glucose and lipid metabolism.NEW & NOTEWORTHY This study shows that the energy sensor and transducer, AMP-activated protein kinase (AMPK), is necessary for an exercise training-induced: 1) increase in liver glycogen that is necessary for accelerated glycogenolysis during exercise, 2) decrease in liver glycerolipids independent of tricarboxylic acid (TCA) cycle flux, and 3) decline in the desaturation and elongation of fatty acids comprising liver diacylglycerides. The mechanisms defined in these studies have implications for use of regular exercise or AMPK-activators in patients with fatty liver.


Asunto(s)
Proteínas Quinasas Activadas por AMP , Hígado Graso , Humanos , Animales , Ratones , Proteínas Quinasas Activadas por AMP/metabolismo , Glucógeno Hepático , Hígado/metabolismo , Glucosa/metabolismo , Hígado Graso/metabolismo , Ácidos Grasos/metabolismo
15.
bioRxiv ; 2023 Nov 16.
Artículo en Inglés | MEDLINE | ID: mdl-38014154

RESUMEN

Increased deposition of extracellular matrix (ECM) components such as collagens and hyaluronan contributes to the pathogenesis of obesity-associated insulin resistance in muscle, liver, and adipose tissue. Despite the significance of the heart in cardiovascular and metabolic diseases, maladaptive ECM remodelling in obesity-associated cardiac insulin resistance and cardiac dysfunction has not been studied. Using genetic and pharmacological approaches in mice fed a high fat (HF) diet, we demonstrated a tight association between increased ECM deposition with cardiac insulin resistance. Increased collagen deposition by genetic deletion of matrix metalloproteinase 9 (MMP9) exacerbated cardiac insulin resistance and decreased hyaluronan deposition by treatment with PEGylated human recombinant hyaluronidase PH20 (PEGPH20) improved cardiac insulin resistance in obese mice. These relationships corresponded to functional changes in the heart. PEGPH20 treatment in obese mice ameliorated HF diet-induced abnormal myocardial remodelling. In addition to hyaluronan, increased collagen deposition is a characteristic of the obese mouse heart. We further demonstrated that pirfenidone, a clinically available anti-fibrotic medication which inhibits collagen expression, improved cardiac insulin resistance and cardiac function in obese mice. Our results provide important new insights into the role of ECM remodelling in the pathogenesis of cardiac insulin resistance and associated dysfunction in obesity of distinct mouse models. These findings support the novel therapeutic potential of targeting early cardiac ECM abnormalities in the prevention and treatment of obesity-related cardiovascular complications.

16.
bioRxiv ; 2023 Nov 17.
Artículo en Inglés | MEDLINE | ID: mdl-38014310

RESUMEN

Mammals are protected from changes in environmental temperature by altering energetic processes that modify heat production. Insulin is the dominant stimulus of glucose uptake and metabolism, which are fundamental for thermogenic processes. The purpose of this work was to determine the interaction of ambient temperature induced changes in energy expenditure (EE) on the insulin sensitivity of glucose fluxes. Short-term and adaptive responses to thermoneutral temperature (TN, ~28°C) and room (laboratory) temperature (RT, ~22°C) were studied in mice. This range of temperature does not cause detectable changes in circulating catecholamines or shivering and postabsorptive glucose homeostasis is maintained. We tested the hypothesis that a decrease in EE that occurs with TN causes insulin resistance and that this reduction in insulin action and EE is reversed upon short term (<12h) transition to RT. Insulin-stimulated glucose disposal (Rd) and tissue specific glucose uptake were assessed combining isotopic tracers with hyperinsulinemic-euglycemic clamps. EE and insulin-stimulated Rd are both decreased (~50%) in TN-adapted vs RT-adapted mice. When RT-adapted mice are switched to TN, EE rapidly decreases and Rd is reduced by ~50%. TN-adapted mice switched to RT exhibit a rapid increase in EE, but whole body insulin-stimulated Rd remains at the low rates of TN-adapted mice. In contrast, whole body glycolytic flux rose with EE. This higher EE occurs without increasing glucose uptake from the blood, but rather by diverting glucose from glucose storage to glycolysis. In addition to adaptations in insulin action, 'insulin-independent' glucose uptake in brown fat is exquisitely sensitive to thermoregulation. These results show that insulin action adjusts to non-stressful changes in ambient temperature to contribute to the support of body temperature homeostasis without compromising glucose homeostasis.

17.
J Genet Couns ; 2023 Sep 04.
Artículo en Inglés | MEDLINE | ID: mdl-37667592

RESUMEN

The genetics and disability communities have had a complicated relationship that is rooted in the history of the eugenics movement. Disability scholars claim that in order for healthcare professionals to provide optimal services to disabled patients, disability education must be implemented into healthcare training programs. No studies have explored the perspectives of disability advocates regarding the implementation and use of disability training in genetic counseling. This exploratory study recruited 13 advocates with lived experience of disability and genetic counseling exposure to participate in a semi-structured interview to share their recommendations for disability education opportunities in genetic counseling training programs and their perceived benefits of increased student exposure to disability. All advocates received genetic counseling themselves and four advocates reported working with genetic counselors in the advocacy setting. Advocates recounted their experiences working with genetic counselors, identifying qualities they deemed critical for effective counseling. All the advocates expressed interest in participating in experiential opportunities, with few concerns noted. The most frequently discussed recommendations for disability training included inviting advocates to speak in classrooms, and having students shadow disabled individuals. Advocates noted barriers to consider when implementing such educational opportunities, such as accessibility issues. Potential benefits of implementing disability education for students included providing students with a broader scope of knowledge and a deeper understanding of disability and resources available to the disability community. This novel study found that advocates are interested in participating in genetic counseling education, with recommendations on preferred experiential learning. By increasing a genetic counseling student's exposure to a disability, they may develop a comprehensive understanding of life with a disability, which may improve genetic counseling services to those with newly diagnosed disabilities.

18.
Prehosp Emerg Care ; : 1-8, 2023 Jul 18.
Artículo en Inglés | MEDLINE | ID: mdl-37436072

RESUMEN

BACKGROUND: First responders play a vital role in the United States opioid drug overdose crisis, a public health emergency that has claimed many lives. OBJECTIVE: We sought to investigate first responders' experiences and attitudes toward opioid overdose emergencies and the ongoing crisis, as well as emotional effects, coping strategies, and support systems. METHODS: A convenience sample of first responders (n = 18) at the Columbus Fire Division, with experience responding to opioid emergencies, participated in semi-structured telephone interviews between September 2018 and February 2019. Interviews were recorded, transcribed verbatim, and analyzed using content analysis for themes. RESULTS: While almost all participants described overdose emergencies as routine, they recalled some as memorable and emotionally impactful. Almost all respondents were frustrated by the high rates of overdose among their patients and the lack of sustainable improvements in outcomes, yet expressed a strong moral commitment to caring for patients and saving lives. Themes of burnout, compassion fatigue, and hopelessness emerged, as did themes of increased compassion and empathy. Support for personnel experiencing emotional difficulty was either lacking or underutilized. Further, many felt public policies should prioritize more permanent resources and improve access to care, and believed that people who use drugs should face greater accountability. CONCLUSION: First responders perceive a moral and professional duty to treat patients who overdose, despite their frustrations. They may benefit from additional occupational support to cope with the resultant emotional effects of their role in the crisis. Addressing macro-level factors contributing to the overdose crisis and improving patient outcomes could also positively affect first responder wellbeing.

19.
Hastings Cent Rep ; 53(3): 25-34, 2023 05.
Artículo en Inglés | MEDLINE | ID: mdl-37285413

RESUMEN

Home care is one of the fastest-growing industries in the United States, providing valuable opportunities for millions of older adults and people with disabilities to live at home rather than in institutional settings. Home care workers assist clients with essential activities of daily living, but their wages and working conditions generally fail to reflect the importance of their work. Drawing on the work of Eva Feder Kittay and other care ethicists, we argue that good care involves attending to the needs of another out of a concern for their well-being. Such care should be standard in the home care system. Yet, because of the pervasive racial, gender, and economic inequalities that the home care industry perpetuates, home care workers and their clients cannot reasonably be expected to care about each other. We endorse reforms aimed at enabling home care workers and their clients to form and maintain professional relationships that cultivate care..


Asunto(s)
Servicios de Atención de Salud a Domicilio , Auxiliares de Salud a Domicilio , Humanos , Estados Unidos , Anciano , Actividades Cotidianas
20.
Life Metab ; 2(4)2023 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-37383542

RESUMEN

Obesity causes extracellular matrix (ECM) remodelling which can develop into serious pathology and fibrosis, having metabolic effects in insulin-sensitive tissues. The ECM components may be increased in response to overnutrition. This review will focus on specific obesity-associated molecular and pathophysiological mechanisms of ECM remodelling and the impact of specific interactions on tissue metabolism. In obesity, complex network of signalling molecules such as cytokines and growth factors have been implicated in fibrosis. Increased ECM deposition contributes to the pathogenesis of insulin resistance at least in part through activation of cell surface integrin receptors and CD44 signalling cascades. These cell surface receptors transmit signals to the cell adhesome which orchestrates an intracellular response that adapts to the extracellular environment. Matrix proteins, glycoproteins, and polysaccharides interact through ligand-specific cell surface receptors that interact with the cytosolic adhesion proteins to elicit specific actions. Cell adhesion proteins may have catalytic activity or serve as scaffolds. The vast number of cell surface receptors and the complexity of the cell adhesome have made study of their roles challenging in health and disease. Further complicating the role of ECM-cell receptor interactions is the variation between cell types. This review will focus on recent insights gained from studies of two highly conserved, ubiquitously axes and how they contribute to insulin resistance and metabolic dysfunction in obesity. These are the collagen-integrin receptor-IPP (ILK-PINCH-Parvin) axis and the hyaluronan-CD44 interaction. We speculate that targeting ECM components or their receptor-mediated cell signalling may provide novel insights into the treatment of obesity-associated cardiometabolic complications.

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