Browsing by Subject "Non-insulin-dependent diabetes"

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    Activities and support provided by family caregivers of persons with type 2 diabetes
    (2016-03-11) Scarton, Lisa J.; Bakas, Tamilyn; Miller, Wendy; McLennon, Susan M.; Huber, Lesa
    Type 2 diabetes, a chronic condition affecting millions, continues to rise in epidemic proportions. Type 2 diabetes, managed through lifestyle changes, affects the entire family. Family caregivers provide vital support to these individuals; however, little research has been conducted surrounding the perceived difficulty or ease of caregiver activity and supportive behaviors. The purpose of this dissertation was to develop and psychometrically test a scale that measures this difficulty or ease of activities and behaviors. This was accomplished through the compilation of three distinct manuscripts. First, an integrative review was conducted to identify what is known regarding needs and concerns of family caregivers of persons with type 2 diabetes; findings revealed a need for more research. Then, based on these recommendations, a qualitative study was conducted that explored the needs and concerns identified by 33 American Indian, African American, and White family caregivers. All these caregivers had similar concerns related to needing general diabetes information, providing support to the family member, and taking care of their own health. Study themes were used to develop items for a new instrument, the Diabetes Caregiver Activity and Support Scale (D-CASS) that was psychometrically tested with 101 American Indian, African American, and White family caregivers of persons with type 2 diabetes. This study used a cross-sectional, descriptive-correlational design and provided evidence of internal consistency reliability (α = .82) and two-week test-retest reliability (intraclass correlation coefficient = .70) for the D-CASS. Criterion-related validity was established using a single-item criterion measuring overall how easy or difficult it was for caregivers to provide care for their loved ones (r = .65, p < .01). Unidimensionality was supported by factor analysis, with loadings ranging from .45 to .70, with 32% of the variance explained by the first factor (eigenvalue = 4.02). Model testing through a series of three hierarchical multiple regressions guided by a conceptual model provided further evidence of construct validity for the D-CASS. This dissertation provided better understanding of needs and concerns of family caregivers of persons with type 2 diabetes and led to the development of a psychometrically sound diabetes-specific instrument for future research.
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    Loss of mTORC1 signalling impairs β-cell homeostasis and insulin processing
    (Nature Communication Group, 2017-07-12) Blandino-Rosano, Manuel; Barbaresso, Rebecca; Jimenez-Palomares, Margarita; Bozadjieva, Nadejda; Werneck-de-Castro, Joao Pedro; Hatanaka, Masayuki; Mirmira, Raghavendra G.; Sonenberg, Nahum; Liu, Ming; Rüegg, Markus A.; Hall, Michael N.; Bernal-Mizrachi, Ernesto; Pediatrics, School of Medicine
    Deregulation of mTOR complex 1 (mTORC1) signalling increases the risk for metabolic diseases, including type 2 diabetes. Here we show that β-cell-specific loss of mTORC1 causes diabetes and β-cell failure due to defects in proliferation, autophagy, apoptosis and insulin secretion by using mice with conditional (βraKO) and inducible (MIP-βraKOf/f) raptor deletion. Through genetic reconstitution of mTORC1 downstream targets, we identify mTORC1/S6K pathway as the mechanism by which mTORC1 regulates β-cell apoptosis, size and autophagy, whereas mTORC1/4E-BP2-eIF4E pathway regulates β-cell proliferation. Restoration of both pathways partially recovers β-cell mass and hyperglycaemia. This study also demonstrates a central role of mTORC1 in controlling insulin processing by regulating cap-dependent translation of carboxypeptidase E in a 4EBP2/eIF4E-dependent manner. Rapamycin treatment decreases CPE expression and insulin secretion in mice and human islets. We suggest an important role of mTORC1 in β-cells and identify downstream pathways driving β-cell mass, function and insulin processing.
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    Obesity alters global response to ischemia and GLP-1 agonism
    (2016-05-13) Sassoon, Daniel Jay; Tune, Johnathan; Mather, Kieren
    Glucagon-like peptide 1 (GLP-1) receptor agonists are a class of incretin based therapeutics which aid in blood glucose management in Type II diabetes mellitus (T2DM). Recent studies have demonstrated direct cardiovascular benefits conferred by these agents including protection in ischemia and heart failure. Despite these observations, human clinical trials fail to support improvements in cardiovascular outcomes independent of glucose lowering effects in the T2DM populations. Prior data from our lab demonstrate that obesity impairs GLP-1 associated increases in myocardial glucose uptake. However, the reasons for this impairment/resistance to cardiac effects of GLP-1 in the setting of obesity remain ill defined. This investigation tested the hypothesis that underlying differences in the cardiac proteome and microRNA (miR) transcriptome could contribute to distinct cardiac responses to ischemia and activation of GLP-1 signaling in the setting of obesity. To identify whether obesity modulated cardiac functional responses to GLP 1 related drugs, we first examined the effects of obesity on cardiac function, miR transcriptome, and proteome in response to short duration ischemia-reperfusion (I/R). We observed divergent physiologic responses (e.g. increased diastolic volume and systolic pressure in lean, decreased diastolic volumes in obese) to regional I/R in obese vs lean hearts that were associated with significant molecular changes as detected by protein mass spectrometry and miR microarray. Molecular changes were related to myocardial calcium handling (SERCA2a, histidine-rich Ca2+ binding protein), myocardial structure and function (titin), and miRs relating to cardiac metabolism, hypertrophy, and cell death, including miR-15, miR-30, miR-199a, miR-214. Importantly, these effects were modified differently by GLP-1 agonism in lean vs obese swine. Additional studies investigated the functional effects of 30 days of treatment with the GLP-1 analogue liraglutide on a model of slowly-developing, unrelieved coronary ischemia. Liraglutide failed to reduce infarct size or collagen deposition. However, analysis of left ventricular pressure-volume relationships support that liraglutide improved diastolic relaxation/filling, load-dependent indices of cardiac function, and cardiac efficiency in response to sympathetic stimulation in obese swine. Taken together, these findings support that miR and proteomic differences underlie distinct changes in functional cardiac responses to I/R and pharmacologic activation of GLP-1 signaling in the setting of obesity.
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    Regulation of glucose homeostasis by Doc2b and Munc18 proteins.
    (2014-01) Ramalingam, Latha; Thurmond, Debbie C.; Elmendorf, Jeffrey S.; Mirmira, Raghavendra G.; Roach, Peter J.
    Glucose homeostasis is maintained through the coordinated actions of insulin secretion from pancreatic beta cells and insulin action in peripheral tissues. Dysfunction of insulin action yields insulin resistance, and when coupled with altered insulin secretion, results in type 2 diabetes (T2D). Exocytosis of intracellular vesicles, such as insulin granules and glucose transporter (GLUT4) vesicles is carried out by similar SNARE (soluble NSF attachment receptor) protein isoforms and Munc18 proteins. An additional regulatory protein, Doc2b, was implicated in the regulation of these particular exocytosis events in clonal cell lines, but relevance of Doc2b in the maintenance of whole body glucose homeostasis in vivo remained unknown. The objective of my doctoral work was to delineate the mechanisms underlying regulation of insulin secretion and glucose uptake by Doc2b in effort to identify new therapeutic targets within these processes for the prevention and/or treatment of T2D. Towards this, mice deficient in Doc2b (Doc2b-/- knockout mice) were assessed for in vivo alterations in glucose homeostasis. Doc2b knockout mice were highly susceptible to preclinical T2D, exhibiting significant whole-body glucose intolerance related to insulin secretion insufficiency as well as peripheral insulin resistance. These phenotypic defects were accounted for by defects in assembly of SNARE complexes. Having determined that Doc2b was required in the control over whole body glycemia in vivo, whether Doc2b is also limiting for these mechanisms in vivo was examined. To study this, novel Doc2b transgenic (Tg) mice were engineered to express ~3 fold more Doc2b exclusively in pancreas, skeletal muscle and fat tissues. Compared to normal littermate mice, Doc2b Tg mice had improved glucose tolerance, related to concurrent enhancements in insulin mumsecretion from beta cells and insulin-stimulated glucose uptake in the skeletal muscle. At the molecular level, Doc2b overexpression promoted SNARE complex assembly, increasing exocytotic capacities in both cellular processes. These results unveiled the concept that intentional elevation of Doc2b could provide a means of mitigating two primary aberrations underlying T2D development.