Joseph T. Brozinick
National Institutes of Health
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Featured researches published by Joseph T. Brozinick.
American Journal of Physiology-endocrinology and Metabolism | 1998
David J. Dean; Joseph T. Brozinick; Samuel W. Cushman; Gregory D. Cartee
Reduced calorie intake [calorie restriction (CR); 60% of ad libitum (AL)] leads to enhanced glucose transport without altering total GLUT-4 glucose transporter abundance in skeletal muscle. Therefore, we tested the hypothesis that CR (20 days) alters the subcellular distribution of GLUT-4. Cell surface GLUT-4 content was higher in insulin-stimulated epitrochlearis muscles from CR vs. AL rats. The magnitude of this increase was similar to the CR-induced increase in glucose transport, and GLUT-4 activity (glucose transport rate divided by cell surface GLUT-4) was unaffected by diet. The CR effect was specific to the insulin-mediated pathway, as evidenced by the observations that basal glucose transport and cell surface GLUT-4 content, as well as hypoxia-stimulated glucose transport, were unchanged by diet. CR did not alter insulins stimulation of insulin receptor substrate (IRS)-1-associated phosphatidylinositol 3-kinase (PI3K) activity. Muscle abundance of IRS-2 and p85 subunit of PI3K were unaltered by diet, but IRS-1 content was lower in CR vs. AL. These data demonstrate that, despite IRS-1-PI3K activity similar to AL, CR specifically increases insulins activation of glucose transport by enhancing the steady-state proportion of GLUT-4 residing on the cell surface.
American Journal of Physiology-endocrinology and Metabolism | 1998
Thomas H. Reynolds; Joseph T. Brozinick; Marc A. Rogers; Samuel W. Cushman
We have previously reported that exercise training is associated with enhanced insulin-stimulated glucose transport activity and inhibited hypoxia-stimulated glucose transport activity in rat epitrochlearis muscle. Here we examine the potential role of muscle glycogen in the inhibited glucose transport response to hypoxia. Three days of swim training (2 × 3 h/day) produce a 100% increase in glycogen and a 70% increase in GLUT-4 in epitrochlearis muscle. Glucose transport after 1 h of hypoxia in muscles from fed exercise-trained (ET) rats is not significantly elevated above basal and is 40% lower than that in muscles from fed sedentary (SED) rats. Glycogen levels after 1 h of hypoxia are reduced by 27 and 64% in muscles from fed ET and fed SED rats, respectively. After 2 h of hypoxia, glucose transport is significantly increased above basal in muscles from fed ET rats, but this response is still 55% lower than that in muscles from fed SED rats. After 2 h of hypoxia, glycogen is reduced by 50 and 83% in muscles from fed ET and fed SED rats, respectively. After a modified overnight fast (≈4.5 g of chow), the glucose transport and glycogen responses to 1 h of hypoxia are not significantly different between muscles from ET and SED rats. These findings demonstrate a strong inverse relationship between glycogen and hypoxia-stimulated glucose transport activity and that high levels of glycogen contribute to the inhibited glucose transport response to hypoxia. Furthermore, failure of the overexpression of GLUT-4 after exercise training to enhance the glucose transport response to contraction/hypoxia suggests selective targeting of the additional GLUT-4 to the insulin-responsive pool.We have previously reported that exercise training is associated with enhanced insulin-stimulated glucose transport activity and inhibited hypoxia-stimulated glucose transport activity in rat epitrochlearis muscle. Here we examine the potential role of muscle glycogen in the inhibited glucose transport response to hypoxia. Three days of swim training (2 x 3 h/day) produce a 100% increase in glycogen and a 70% increase in GLUT-4 in epitrochlearis muscle. Glucose transport after 1 h of hypoxia in muscles from fed exercise-trained (ET) rats is not significantly elevated above basal and is 40% lower than that in muscles from fed sedentary (SED) rats. Glycogen levels after 1 h of hypoxia are reduced by 27 and 64% in muscles from fed ET and fed SED rats, respectively. After 2 h of hypoxia, glucose transport is significantly increased above basal in muscles from fed ET rats, but this response is still 55% lower than that in muscles from fed SED rats. After 2 h of hypoxia, glycogen is reduced by 50 and 83% in muscles from fed ET and fed SED rats, respectively. After a modified overnight fast (approximately 4.5 g of chow), the glucose transport and glycogen responses to 1 h of hypoxia are not significantly different between muscles from ET and SED rats. These findings demonstrate a strong inverse relationship between glycogen and hypoxia-stimulated glucose transport activity and that high levels of glycogen contribute to the inhibited glucose transport response to hypoxia. Furthermore, failure of the overexpression of GLUT-4 after exercise training to enhance the glucose transport response to contraction/hypoxia suggests selective targeting of the additional GLUT-4 to the insulin-responsive pool.
Journal of Medicinal Chemistry | 2016
Michael J. Genin; Isabel C. Gonzalez Valcarcel; William Glen Holloway; Jason Lamar; Marian Mosior; Eric Hawkins; Thomas Estridge; Jeffrey Weidner; Thomas W. Seng; David Yurek; Lisa A. Adams; Jennifer Weller; Vincent L. Reynolds; Joseph T. Brozinick
To develop novel treatments for type 2 diabetes and dyslipidemia, we pursued inhibitors of serine palmitoyl transferase (SPT). To this end compounds 1 and 2 were developed as potent SPT inhibitors in vitro. 1 and 2 reduce plasma ceramides in rodents, have a slight trend toward enhanced insulin sensitization in DIO mice, and reduce triglycerides and raise HDL in cholesterol/cholic acid fed rats. Unfortunately these molecules cause a gastric enteropathy after chronic dosing in rats.
Diabetes | 2003
Joseph T. Brozinick; Brian R. Roberts; G. Lynis Dohm
Diabetes | 2002
Garret J. Etgen; Brian A. Oldham; William T. Johnson; Carol L. Broderick; Chahrzad R. Montrose; Joseph T. Brozinick; Elizabeth A. Misener; James S. Bean; William R. Bensch; Dawn A. Brooks; Anthony J. Shuker; Christopher John Rito; James R. McCarthy; Robert Ardecky; John S. Tyhonas; Sharon L. Dana; James M. Bilakovics; James R. Paterniti; Kathleen M. Ogilvie; Sha Liu; Raymond F. Kauffman
American Journal of Physiology-endocrinology and Metabolism | 1992
E. A. Banks; Joseph T. Brozinick; B. B. Yaspelkis; H. Y. Kang; John L. Ivy
Journal of Medicinal Chemistry | 2004
Thomas A. Engler; James Robert Henry; Sushant Malhotra; Brian Eugene Cunningham; Kelly Wayne Furness; Joseph T. Brozinick; Timothy Paul Burkholder; Michael P. Clay; Joshua Ryan Clayton; Clive Gideon Diefenbacher; Eric Hawkins; Philip W. Iversen; Yihong Li; Terry D. Lindstrom; Angela Lynn Marquart; Johnathan Alexander Mclean; David Mendel; Elizabeth A. Misener; Daniel A. Briere; John O'Toole; Warren J. Porter; Steven Queener; Jon K. Reel; Rebecca A. Owens; Richard A. Brier; Thomas E. Eessalu; Jill R. Wagner; and Robert M. Campbell; Renee Vaughn
Journal of Applied Physiology | 1992
Joseph T. Brozinick; G. J. Etgen; B. B. Yaspelkis; John L. Ivy
Molecular Endocrinology | 2005
Anne Reifel-Miller; Keith A. Otto; Eric Hawkins; Robert J. Barr; William R. Bensch; Chris Bull; Sharon Dana; Kay Klausing; Jose-Alfredo Martin; Ronit Rafaeloff-Phail; Chahrzad Rafizadeh-Montrose; Gary A. Rhodes; Roger L. Robey; Isabel Rojo; Deepa Rungta; David Snyder; Kelly L. Wilbur; Tony Y. Zhang; Richard W. Zink; Alan M. Warshawsky; Joseph T. Brozinick
American Journal of Physiology-endocrinology and Metabolism | 2007
Laura K. Barré; Charles C. Richardson; Michael F. Hirshman; Joseph T. Brozinick; Steven Fiering; Bruce E. Kemp; Laurie J. Goodyear; Lee A. Witters