Obesity, insulin resistance, and type 2 diabetes mellitus are associated with diabetic cognopathy... more Obesity, insulin resistance, and type 2 diabetes mellitus are associated with diabetic cognopathy. This study tested the hypothesis that neurovascular unit(s) (NVU) within cerebral cortical gray matter regions may depict abnormal cellular remodeling. The monogenic (Leprdb) female diabetic db/db [BKS.CgDock7m +/+Leprdb/J] (DBC) mouse model was utilized for this ultrastructural study. Upon sacrifice (20 weeks), left-brain hemispheres of the DBC and age-matched nondiabetic control C57BL/KsJ (CKC) mice were immediately immersion-fixed. We observed an attenuation/loss of endothelial blood–brain barrier tight/adherens junctions and pericytes, thickened basement membranes, adherent red and white blood cells, neurovascular unit microbleeds and pathologic remodeling of protoplasmic astrocytes. In this second of a three-part series, we focus on the observational ultrastructural remodeling of microglia and mitochondria in relation to the NVU in leptin receptor deficient DBC models. This study ...
Type 2 diabetes mellitus is a multifactorial disease with polygenic and environmental stressors r... more Type 2 diabetes mellitus is a multifactorial disease with polygenic and environmental stressors resulting in multiple metabolic toxicities and islet oxidative stress. We have integrated the role of the islet renin-angiotensin system (RAS) in the pathogenesis of early islet fibrosis utilizing the transgenic (mRen2)27 rodent model of hypertension and tissue RAS overexpression. The Ren2 pancreatic islet tissue was evaluated with transmission electron microscopy to study both early cellular and extracellular matrix remodeling. Four 9- to 10-week-old male Ren2 untreated models and four Sprague Dawley sex and age matched controls were used. Ultrastructural study to compare pancreatic islet tissue. Only qualitative and observational transmission electron microscopy findings are reported. Major remodeling differences in the Ren2 model were found to be located within the islet exocrine interface, including deposition of early fibrillar-banded collagen (fibrosis) and cellular remodeling of th...
Amyloid deposits within the islet of the pancreas have been known for a century. In 1987, the isl... more Amyloid deposits within the islet of the pancreas have been known for a century. In 1987, the islet amyloid precursor polypeptide (IAPP) amylin (a 37 amino acid) was discovered. Recently there has been an explosion of amylin's importance in the development of type 2 diabetes mellitus (T2DM). This review is intended to share what is understood about amylin derived amyloid and the role it plays in T2DM. Whether islet amyloid is an epiphenomenona, a tombstone, or a trigger it leaves an indelible footprint in greater that 70% of the patients with T2DM. There is current data supporting the damaging role of intermediate sized toxic amyloid particles to the beta cell resulting in a beta cell defect which contributes to a relative deficiency or loss of insulin secretion. Within the islet there is an intense redox stress which may be associated with the unfolding of amylin's native secondary structure compounding its amyloidogenic properties. In addition to the beta cell defect there...
Remodeling of the endocrine pancreas, caused by the deleterious effects of amylin as it is co-syn... more Remodeling of the endocrine pancreas, caused by the deleterious effects of amylin as it is co-synthesized, co-packaged, and co-secreted with insulin, gives clinicians and researchers cause to ponder. A literature search was done, and relevant publications and texts on amylin and islet amyloid polypeptide (IAPP) were reviewed. The mechanisms and clinical consequences attributed to the remodeling of the endocrine pancreas, along with proposals for reevaluating the methods of treating patients who have type 2 diabetes are illustrated and discussed. In addition to controlling the devastating effects ofglucotoxicity, lipotoxicity, and hypertension, we should consider the newer hypoglycemic agents with regard to their effects on the remodeling of the endocrine pancreas. This remodeling results in structural and subsequent functional changes, causing continued elevations of hemoglobin A1C. Studies are indicated to determine whether amylin (IAPP) may be implicated in the remodeling of the a...
Redox stress, reactive oxygen species, reactive nitrogen species, and oxygen free radicals ("... more Redox stress, reactive oxygen species, reactive nitrogen species, and oxygen free radicals ("toxic oxygen") are increasingly being reported as important cellular signaling mechanisms. It has been known for over a hundred years that type 2 diabetes mellitus is a manifold disease, not only in its etiology, but also in its associated manifold toxicities and multiple complications of the diabetic opathies. The presence of islet amyloid has also been described in association with type 2 diabetes mellitus for a century. This review will attempt to remain focused on the relationship between redox stress, the reactive oxygen species and the reactive nitrogen species in the islet, and how these interact with the multiplicative effect of the toxicities of insulin resistance, metabolic syndrome, amylin (hyperamylinemia), amylin derived islet amyloid and type 2 diabetes mellitus. Redox sensitive cellular signaling systems play an important role in the development, progressive nature (...
Metabolic syndrome, insulin resistance, prediabetes, and overt type 2 diabetes mellitus are assoc... more Metabolic syndrome, insulin resistance, prediabetes, and overt type 2 diabetes mellitus are associated with an accelerated atherosclerosis (atheroscleropathy). This quartet is also associated with multiple metabolic toxicities resulting in the production of reactive oxygen species. The redox stress associated with these reactive oxygen species contribute to the development, progression, and the final fate of the arterial vessel wall in prediabetic and diabetic atheroscleropathy. The prevention of morbidity and mortality of these intersecting metabolic diseases can be approached through comprehensive global risk reduction.
Medical science monitor : international medical journal of experimental and clinical research, 2003
Over the past three decades, we have witnessed an improvement of survival in those patients with ... more Over the past three decades, we have witnessed an improvement of survival in those patients with the trio of metabolic syndrome, prediabetes, and overt type 2 diabetes mellitus. Revolutionary changes in technology and an improved understanding of the mechanisms involved in acute coronary syndromes have resulted in this observation. Due to advances in coronary care, we are currently at a crossroads, wherein, the mortality from acute cardiovascular events have been declining and the mortality associated with this trio has been increasing due to congestive heart failure (CHF). This intersect between the two causes of death represent a challenge for the future, as the numbers of patients with this deadly trio are undergoing exponential growth not only in the U.S. but also abroad as more countries undergo urbanization and adopt a western-type lifestyle of over nutrition and under exercise. Thus, we live to die another day. There are multiple metabolic toxicities in this toxic trio, which...
We have described a 35-year-old man with M pneumoniae pneumonia who had severe hemolytic anemia t... more We have described a 35-year-old man with M pneumoniae pneumonia who had severe hemolytic anemia that appeared to respond well to high-dose corticosteroid therapy. Whether corticosteroids have value in decreasing the severity of hemolytic anemia due to cold agglutinin and other protean extrapulmonary manifestations with M pneumoniae infection needs further controlled study. Our experience suggests that corticosteroids may be beneficial.
Journal of Molecular and Cellular Cardiology, 1996
Human heart matrix metalloproteinases (MMP) are present in the latent form and activated in the f... more Human heart matrix metalloproteinases (MMP) are present in the latent form and activated in the failing heart. To examine whether the MMP activation was due to gene and/or post-translational modification, we analysed tissue from 10 explanted hearts due to coronary heart disease (CHD) and five normal left atrial tissue from donor hearts. Based on in situ immunolabeling MMP-1, tissue inhibitor of metalloproteinase (TIMP-1) and collagen were co-localized in the interstitial tissue. Based on sandwich ELISA, TIMP-1 and MMP-1 levels were 37 +/- 8 ng/mg and 9 +/- 2 ng/mg in normal tissue (P < 0.01) and 12 +/- 5 ng/mg and 75 +/- 11 ng/mg in the infarcted tissue (P < 0.01), respectively. These levels suggest repression of TIMP-1 during myocardial infarction. Northern blot analysis indicated that the mRNAs for both MMP-1 and TIMP-1 were increased three-to four-fold in the infarcted tissue as compared to the normal tissue, suggesting upregulation of MMP and TIMP gene transcription following infarction. Based on in situ tissue overlay zymography, the generalized activation of MMP was observed in the interstitium of the infarcted heart. Zymographic and immunoblot analysis demonstrated the presence of one band at 66 kDa (MMP-2) in the normal tissue and several bands at 92 (MMP-9), 66 (MMP-2) and 54 kDa (MMP-1) in the infarcted heart. Incubation of the zymographic gel with metal chelator (phenanthroline) abolished bands at 92 kDa and 54 kDa but phenanthroline did not abolish the lytic band at 66 kDa. The 66 kDa band was completely abolished in the presence of phenanthroline and phenyl methyl sulfonyl fluoride (PMSF). 2D-zymographic analysis suggested that the lytic band at 66 kDa was a mixture of two neutral proteinases with different isoelectric point. Plasminogen/gelatin zymographic analysis of infarcted tissue extract indicated that the band at 66 kDa was plasmin generated due to increased expression of tissue plasminogen activator (tPA) activity. In relation to increased expression of gelatinase in the infarcted tissue, our data suggest that gelatinase B (92 kDa) is induced in diseased heart. The results suggest that tPA converts plasminogen to plasmin which, in turn, activates MMPs and inactivates TIMP-1 post-translationally following ischemic cardiomyopathy.
TG(mRen2)27 (Ren2) transgenic rats overexpress the mouse renin gene, with subsequent elevated tis... more TG(mRen2)27 (Ren2) transgenic rats overexpress the mouse renin gene, with subsequent elevated tissue ANG II, hypertension, and nephropathy. The proximal tubule cell (PTC) is responsible for the reabsorption of 5–8 g of glomerular filtered albumin each day. Excess filtered albumin may contribute to PTC damage and tubulointerstitial disease. This investigation examined the role of ANG II-induced oxidative stress in PTC structural remodeling: whether such changes could be modified with in vivo treatment with ANG type 1 receptor (AT1R) blockade (valsartan) or SOD/catalase mimetic (tempol). Male Ren2 (6–7 wk old) and age-matched Sprague-Dawley rats were treated with valsartan (30 mg/kg), tempol (1 mmol/l), or placebo for 3 wk. Systolic blood pressure, albuminuria, N-acetyl-β-d-glucosaminidase, and kidney tissue malondialdehyde (MDA) were measured, and ×60,000 transmission electron microscopy images were used to assess PTC microvilli structure. There were significant differences in systol...
The statistical association between endurance exercise capacity and cardiovascular disease sugges... more The statistical association between endurance exercise capacity and cardiovascular disease suggests that impaired aerobic metabolism underlies the cardiovascular disease risk in men and women. To explore this connection, we applied divergent artificial selection in rats to develop low-capacity runner (LCR) and high-capacity runner (HCR) rats and found that disease risks segregated strongly with low running capacity. Here, we tested if inborn low aerobic capacity promotes differential sex-related cardiovascular effects. Compared with HCR males (HCR-M), LCR males (LCR-M) were overweight by 34% and had heavier retroperitoneal, epididymal, and omental fat pads; LCR females (LCR-F) were 20% heavier than HCR females (HCR-F), and their retroperitoneal, but not perireproductive or omental, fat pads were heavier as well. Unlike HCR-M, blood pressure was elevated in LCR-M, and this was accompanied by left ventricular (LV) hypertrophy. Like HCR-F, LCR-F exhibited normal blood pressure and LV w...
The transgenic (mRen2)27 (Ren2) rat overexpresses mouse renin in extrarenal tissues, causing incr... more The transgenic (mRen2)27 (Ren2) rat overexpresses mouse renin in extrarenal tissues, causing increased local synthesis of ANG II, oxidative stress, and hypertension. However, little is known about the role of oxidative stress induced by the tissue renin-angiotensin system (RAS) as a contributing factor in pulmonary hypertension (PH). Using male Ren2 rats, we test the hypothesis that lung tissue RAS overexpression and resultant oxidative stress contribute to PH and pulmonary vascular remodeling. Mean arterial pressure (MAP), right ventricular systolic pressure (RVSP), and wall thickness of small pulmonary arteries (PA), as well as intrapulmonary NADPH oxidase activity and subunit protein expression and reactive oxygen species (ROS), were compared in age-matched Ren2 and Sprague-Dawley (SD) rats pretreated with the SOD/catalase mimetic tempol for 21 days. In placebo-treated Ren2 rats, MAP and RVSP, as well as intrapulmonary NADPH oxidase activity and subunits (Nox2, p22phox, and Rac-1...
Rac1 is a Rho-family small GTP-ase, when activated is pivotal in NAD(P)H oxidase (NOX) activation... more Rac1 is a Rho-family small GTP-ase, when activated is pivotal in NAD(P)H oxidase (NOX) activation and generation of reactive oxygen species (ROS). Evidence links Rac1 activation to receptor-mediated albumin endocytosis in the proximal tubule cell (PTC). Thus in states of albumin overload, Rac1 activation could lead to NOX activation and ROS formation in the PTC. Furthermore, accumulating evidence supports that HMG-CoA reductase inhibition may reduce oxidative stress and albuminuria. To investigate the role of HMG-CoA reductase inhibition of Rac1 and oxidative stress we used the opossum kidney PTC. ROS generation in the PTC was confirmed using oxidative fluorescent dihydroethidium staining. We observed time-dependent increases in NOX activity with bovine serum albumin (albumin) stimulation (500 microg/dl, maximum at 20 min, p < 0.05) that was inhibited in a concentration-dependent manner with the HMG-CoA reductase inhibitor rosuvastatin (1 microM, p < 0.05). Additionally, the Rac1 inhibitor NSC23766 (100 ng/ml) attenuated albumin activation of NOX. Western blot analysis confirmed Rac1 translocation to plasma membrane in the PTC following albumin stimulation and subsequent inhibition by rosuvastatin and NSC23766. These data demonstrate that albumin-mediated increases in NOX activity and ROS in PTC are reversed by inhibition of Rac1 signaling with the use of rosuvastatin.
: Viremia in coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome ... more : Viremia in coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is often only discussed in passing and there are very few references detailing its structural mechanisms. In addition to viremia in the classic closed cardiovascular system, the lymphatic system is discussed in relation to a possible “lympho-viremia”. The cells that comprise each of these separate but interacting systems will be examined and include endothelial cells, erythrocytes, leukocytes (monocytes/monocyte-derived macrophages and resident tissue macrophages) (lymphocytes) (neutrophils) and thrombocytes -platelets. The SARS-CoV-2 virus has been identified in multiple extrapulmonary target organs at autopsy in those with severe COVID-19 requiring intensive care. Vulnerable COVID-19 patients may suffer from multiple storms including viral/virion storm, redox storm, cytokine storm and thrombo-embolic storm. Therefore, it is important that the possible mechanisms of viremia be explored in greater detail and how these mechanisms might affect intravascular blood components, extracellular tissue interstitium and organ structural remodeling and function. While the co-morbidity of T2DM does not increase the risk of acquiring COVID-19, it is commonly accepted that T2DM increases the risk for COVID-19 admissions to hospitals, assisted ventilation, morbidity and mortality. Importantly, the co-existence of T2DM and COVID-19 may have synergistic detrimental outcomes.
Type 2 diabetes is associated with diabetic cognopathy. Anti-hyperglycemic sodium glucose transpo... more Type 2 diabetes is associated with diabetic cognopathy. Anti-hyperglycemic sodium glucose transporter 2 (SGLT2) inhibitors have shown promise in reducing cognitive impairment in mice with type 2 diabetes mellitus. We recently described marked ultrastructural (US) remodeling of the neurovascular unit (NVU) in type 2 diabetic db/db female mice. Herein, we tested whether the SGLT-2 inhibitor, empagliflozin (EMPA), protects the NVU from abnormal remodeling in cortical gray and subcortical white matter. Ten-week-old female wild-type and db/db mice were divided into lean controls (CKC, n = 3), untreated db/db (DBC, n = 3), and EMPA-treated db/db (DBE, n = 3). Empagliflozin was added to mouse chow to deliver 10 mg kg−1 day−1 and fed for ten weeks, initiated at 10 weeks of age. Brains from 20-week-old mice were immediately immersion fixed for transmission electron microscopic study. Compared to CKC, DBC exhibited US abnormalities characterized by mural endothelial cell tight and adherens ju...
Obesity, insulin resistance, and type 2 diabetes mellitus are associated with diabetic cognopathy... more Obesity, insulin resistance, and type 2 diabetes mellitus are associated with diabetic cognopathy. This study tested the hypothesis that neurovascular unit(s) (NVU) within cerebral cortical gray matter regions may depict abnormal cellular remodeling. The monogenic (Leprdb) female diabetic db/db [BKS.CgDock7m +/+Leprdb/J] (DBC) mouse model was utilized for this ultrastructural study. Upon sacrifice (20 weeks), left-brain hemispheres of the DBC and age-matched nondiabetic control C57BL/KsJ (CKC) mice were immediately immersion-fixed. We observed an attenuation/loss of endothelial blood–brain barrier tight/adherens junctions and pericytes, thickened basement membranes, adherent red and white blood cells, neurovascular unit microbleeds and pathologic remodeling of protoplasmic astrocytes. In this second of a three-part series, we focus on the observational ultrastructural remodeling of microglia and mitochondria in relation to the NVU in leptin receptor deficient DBC models. This study ...
Type 2 diabetes mellitus is a multifactorial disease with polygenic and environmental stressors r... more Type 2 diabetes mellitus is a multifactorial disease with polygenic and environmental stressors resulting in multiple metabolic toxicities and islet oxidative stress. We have integrated the role of the islet renin-angiotensin system (RAS) in the pathogenesis of early islet fibrosis utilizing the transgenic (mRen2)27 rodent model of hypertension and tissue RAS overexpression. The Ren2 pancreatic islet tissue was evaluated with transmission electron microscopy to study both early cellular and extracellular matrix remodeling. Four 9- to 10-week-old male Ren2 untreated models and four Sprague Dawley sex and age matched controls were used. Ultrastructural study to compare pancreatic islet tissue. Only qualitative and observational transmission electron microscopy findings are reported. Major remodeling differences in the Ren2 model were found to be located within the islet exocrine interface, including deposition of early fibrillar-banded collagen (fibrosis) and cellular remodeling of th...
Amyloid deposits within the islet of the pancreas have been known for a century. In 1987, the isl... more Amyloid deposits within the islet of the pancreas have been known for a century. In 1987, the islet amyloid precursor polypeptide (IAPP) amylin (a 37 amino acid) was discovered. Recently there has been an explosion of amylin's importance in the development of type 2 diabetes mellitus (T2DM). This review is intended to share what is understood about amylin derived amyloid and the role it plays in T2DM. Whether islet amyloid is an epiphenomenona, a tombstone, or a trigger it leaves an indelible footprint in greater that 70% of the patients with T2DM. There is current data supporting the damaging role of intermediate sized toxic amyloid particles to the beta cell resulting in a beta cell defect which contributes to a relative deficiency or loss of insulin secretion. Within the islet there is an intense redox stress which may be associated with the unfolding of amylin's native secondary structure compounding its amyloidogenic properties. In addition to the beta cell defect there...
Remodeling of the endocrine pancreas, caused by the deleterious effects of amylin as it is co-syn... more Remodeling of the endocrine pancreas, caused by the deleterious effects of amylin as it is co-synthesized, co-packaged, and co-secreted with insulin, gives clinicians and researchers cause to ponder. A literature search was done, and relevant publications and texts on amylin and islet amyloid polypeptide (IAPP) were reviewed. The mechanisms and clinical consequences attributed to the remodeling of the endocrine pancreas, along with proposals for reevaluating the methods of treating patients who have type 2 diabetes are illustrated and discussed. In addition to controlling the devastating effects ofglucotoxicity, lipotoxicity, and hypertension, we should consider the newer hypoglycemic agents with regard to their effects on the remodeling of the endocrine pancreas. This remodeling results in structural and subsequent functional changes, causing continued elevations of hemoglobin A1C. Studies are indicated to determine whether amylin (IAPP) may be implicated in the remodeling of the a...
Redox stress, reactive oxygen species, reactive nitrogen species, and oxygen free radicals ("... more Redox stress, reactive oxygen species, reactive nitrogen species, and oxygen free radicals ("toxic oxygen") are increasingly being reported as important cellular signaling mechanisms. It has been known for over a hundred years that type 2 diabetes mellitus is a manifold disease, not only in its etiology, but also in its associated manifold toxicities and multiple complications of the diabetic opathies. The presence of islet amyloid has also been described in association with type 2 diabetes mellitus for a century. This review will attempt to remain focused on the relationship between redox stress, the reactive oxygen species and the reactive nitrogen species in the islet, and how these interact with the multiplicative effect of the toxicities of insulin resistance, metabolic syndrome, amylin (hyperamylinemia), amylin derived islet amyloid and type 2 diabetes mellitus. Redox sensitive cellular signaling systems play an important role in the development, progressive nature (...
Metabolic syndrome, insulin resistance, prediabetes, and overt type 2 diabetes mellitus are assoc... more Metabolic syndrome, insulin resistance, prediabetes, and overt type 2 diabetes mellitus are associated with an accelerated atherosclerosis (atheroscleropathy). This quartet is also associated with multiple metabolic toxicities resulting in the production of reactive oxygen species. The redox stress associated with these reactive oxygen species contribute to the development, progression, and the final fate of the arterial vessel wall in prediabetic and diabetic atheroscleropathy. The prevention of morbidity and mortality of these intersecting metabolic diseases can be approached through comprehensive global risk reduction.
Medical science monitor : international medical journal of experimental and clinical research, 2003
Over the past three decades, we have witnessed an improvement of survival in those patients with ... more Over the past three decades, we have witnessed an improvement of survival in those patients with the trio of metabolic syndrome, prediabetes, and overt type 2 diabetes mellitus. Revolutionary changes in technology and an improved understanding of the mechanisms involved in acute coronary syndromes have resulted in this observation. Due to advances in coronary care, we are currently at a crossroads, wherein, the mortality from acute cardiovascular events have been declining and the mortality associated with this trio has been increasing due to congestive heart failure (CHF). This intersect between the two causes of death represent a challenge for the future, as the numbers of patients with this deadly trio are undergoing exponential growth not only in the U.S. but also abroad as more countries undergo urbanization and adopt a western-type lifestyle of over nutrition and under exercise. Thus, we live to die another day. There are multiple metabolic toxicities in this toxic trio, which...
We have described a 35-year-old man with M pneumoniae pneumonia who had severe hemolytic anemia t... more We have described a 35-year-old man with M pneumoniae pneumonia who had severe hemolytic anemia that appeared to respond well to high-dose corticosteroid therapy. Whether corticosteroids have value in decreasing the severity of hemolytic anemia due to cold agglutinin and other protean extrapulmonary manifestations with M pneumoniae infection needs further controlled study. Our experience suggests that corticosteroids may be beneficial.
Journal of Molecular and Cellular Cardiology, 1996
Human heart matrix metalloproteinases (MMP) are present in the latent form and activated in the f... more Human heart matrix metalloproteinases (MMP) are present in the latent form and activated in the failing heart. To examine whether the MMP activation was due to gene and/or post-translational modification, we analysed tissue from 10 explanted hearts due to coronary heart disease (CHD) and five normal left atrial tissue from donor hearts. Based on in situ immunolabeling MMP-1, tissue inhibitor of metalloproteinase (TIMP-1) and collagen were co-localized in the interstitial tissue. Based on sandwich ELISA, TIMP-1 and MMP-1 levels were 37 +/- 8 ng/mg and 9 +/- 2 ng/mg in normal tissue (P < 0.01) and 12 +/- 5 ng/mg and 75 +/- 11 ng/mg in the infarcted tissue (P < 0.01), respectively. These levels suggest repression of TIMP-1 during myocardial infarction. Northern blot analysis indicated that the mRNAs for both MMP-1 and TIMP-1 were increased three-to four-fold in the infarcted tissue as compared to the normal tissue, suggesting upregulation of MMP and TIMP gene transcription following infarction. Based on in situ tissue overlay zymography, the generalized activation of MMP was observed in the interstitium of the infarcted heart. Zymographic and immunoblot analysis demonstrated the presence of one band at 66 kDa (MMP-2) in the normal tissue and several bands at 92 (MMP-9), 66 (MMP-2) and 54 kDa (MMP-1) in the infarcted heart. Incubation of the zymographic gel with metal chelator (phenanthroline) abolished bands at 92 kDa and 54 kDa but phenanthroline did not abolish the lytic band at 66 kDa. The 66 kDa band was completely abolished in the presence of phenanthroline and phenyl methyl sulfonyl fluoride (PMSF). 2D-zymographic analysis suggested that the lytic band at 66 kDa was a mixture of two neutral proteinases with different isoelectric point. Plasminogen/gelatin zymographic analysis of infarcted tissue extract indicated that the band at 66 kDa was plasmin generated due to increased expression of tissue plasminogen activator (tPA) activity. In relation to increased expression of gelatinase in the infarcted tissue, our data suggest that gelatinase B (92 kDa) is induced in diseased heart. The results suggest that tPA converts plasminogen to plasmin which, in turn, activates MMPs and inactivates TIMP-1 post-translationally following ischemic cardiomyopathy.
TG(mRen2)27 (Ren2) transgenic rats overexpress the mouse renin gene, with subsequent elevated tis... more TG(mRen2)27 (Ren2) transgenic rats overexpress the mouse renin gene, with subsequent elevated tissue ANG II, hypertension, and nephropathy. The proximal tubule cell (PTC) is responsible for the reabsorption of 5–8 g of glomerular filtered albumin each day. Excess filtered albumin may contribute to PTC damage and tubulointerstitial disease. This investigation examined the role of ANG II-induced oxidative stress in PTC structural remodeling: whether such changes could be modified with in vivo treatment with ANG type 1 receptor (AT1R) blockade (valsartan) or SOD/catalase mimetic (tempol). Male Ren2 (6–7 wk old) and age-matched Sprague-Dawley rats were treated with valsartan (30 mg/kg), tempol (1 mmol/l), or placebo for 3 wk. Systolic blood pressure, albuminuria, N-acetyl-β-d-glucosaminidase, and kidney tissue malondialdehyde (MDA) were measured, and ×60,000 transmission electron microscopy images were used to assess PTC microvilli structure. There were significant differences in systol...
The statistical association between endurance exercise capacity and cardiovascular disease sugges... more The statistical association between endurance exercise capacity and cardiovascular disease suggests that impaired aerobic metabolism underlies the cardiovascular disease risk in men and women. To explore this connection, we applied divergent artificial selection in rats to develop low-capacity runner (LCR) and high-capacity runner (HCR) rats and found that disease risks segregated strongly with low running capacity. Here, we tested if inborn low aerobic capacity promotes differential sex-related cardiovascular effects. Compared with HCR males (HCR-M), LCR males (LCR-M) were overweight by 34% and had heavier retroperitoneal, epididymal, and omental fat pads; LCR females (LCR-F) were 20% heavier than HCR females (HCR-F), and their retroperitoneal, but not perireproductive or omental, fat pads were heavier as well. Unlike HCR-M, blood pressure was elevated in LCR-M, and this was accompanied by left ventricular (LV) hypertrophy. Like HCR-F, LCR-F exhibited normal blood pressure and LV w...
The transgenic (mRen2)27 (Ren2) rat overexpresses mouse renin in extrarenal tissues, causing incr... more The transgenic (mRen2)27 (Ren2) rat overexpresses mouse renin in extrarenal tissues, causing increased local synthesis of ANG II, oxidative stress, and hypertension. However, little is known about the role of oxidative stress induced by the tissue renin-angiotensin system (RAS) as a contributing factor in pulmonary hypertension (PH). Using male Ren2 rats, we test the hypothesis that lung tissue RAS overexpression and resultant oxidative stress contribute to PH and pulmonary vascular remodeling. Mean arterial pressure (MAP), right ventricular systolic pressure (RVSP), and wall thickness of small pulmonary arteries (PA), as well as intrapulmonary NADPH oxidase activity and subunit protein expression and reactive oxygen species (ROS), were compared in age-matched Ren2 and Sprague-Dawley (SD) rats pretreated with the SOD/catalase mimetic tempol for 21 days. In placebo-treated Ren2 rats, MAP and RVSP, as well as intrapulmonary NADPH oxidase activity and subunits (Nox2, p22phox, and Rac-1...
Rac1 is a Rho-family small GTP-ase, when activated is pivotal in NAD(P)H oxidase (NOX) activation... more Rac1 is a Rho-family small GTP-ase, when activated is pivotal in NAD(P)H oxidase (NOX) activation and generation of reactive oxygen species (ROS). Evidence links Rac1 activation to receptor-mediated albumin endocytosis in the proximal tubule cell (PTC). Thus in states of albumin overload, Rac1 activation could lead to NOX activation and ROS formation in the PTC. Furthermore, accumulating evidence supports that HMG-CoA reductase inhibition may reduce oxidative stress and albuminuria. To investigate the role of HMG-CoA reductase inhibition of Rac1 and oxidative stress we used the opossum kidney PTC. ROS generation in the PTC was confirmed using oxidative fluorescent dihydroethidium staining. We observed time-dependent increases in NOX activity with bovine serum albumin (albumin) stimulation (500 microg/dl, maximum at 20 min, p < 0.05) that was inhibited in a concentration-dependent manner with the HMG-CoA reductase inhibitor rosuvastatin (1 microM, p < 0.05). Additionally, the Rac1 inhibitor NSC23766 (100 ng/ml) attenuated albumin activation of NOX. Western blot analysis confirmed Rac1 translocation to plasma membrane in the PTC following albumin stimulation and subsequent inhibition by rosuvastatin and NSC23766. These data demonstrate that albumin-mediated increases in NOX activity and ROS in PTC are reversed by inhibition of Rac1 signaling with the use of rosuvastatin.
: Viremia in coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome ... more : Viremia in coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is often only discussed in passing and there are very few references detailing its structural mechanisms. In addition to viremia in the classic closed cardiovascular system, the lymphatic system is discussed in relation to a possible “lympho-viremia”. The cells that comprise each of these separate but interacting systems will be examined and include endothelial cells, erythrocytes, leukocytes (monocytes/monocyte-derived macrophages and resident tissue macrophages) (lymphocytes) (neutrophils) and thrombocytes -platelets. The SARS-CoV-2 virus has been identified in multiple extrapulmonary target organs at autopsy in those with severe COVID-19 requiring intensive care. Vulnerable COVID-19 patients may suffer from multiple storms including viral/virion storm, redox storm, cytokine storm and thrombo-embolic storm. Therefore, it is important that the possible mechanisms of viremia be explored in greater detail and how these mechanisms might affect intravascular blood components, extracellular tissue interstitium and organ structural remodeling and function. While the co-morbidity of T2DM does not increase the risk of acquiring COVID-19, it is commonly accepted that T2DM increases the risk for COVID-19 admissions to hospitals, assisted ventilation, morbidity and mortality. Importantly, the co-existence of T2DM and COVID-19 may have synergistic detrimental outcomes.
Type 2 diabetes is associated with diabetic cognopathy. Anti-hyperglycemic sodium glucose transpo... more Type 2 diabetes is associated with diabetic cognopathy. Anti-hyperglycemic sodium glucose transporter 2 (SGLT2) inhibitors have shown promise in reducing cognitive impairment in mice with type 2 diabetes mellitus. We recently described marked ultrastructural (US) remodeling of the neurovascular unit (NVU) in type 2 diabetic db/db female mice. Herein, we tested whether the SGLT-2 inhibitor, empagliflozin (EMPA), protects the NVU from abnormal remodeling in cortical gray and subcortical white matter. Ten-week-old female wild-type and db/db mice were divided into lean controls (CKC, n = 3), untreated db/db (DBC, n = 3), and EMPA-treated db/db (DBE, n = 3). Empagliflozin was added to mouse chow to deliver 10 mg kg−1 day−1 and fed for ten weeks, initiated at 10 weeks of age. Brains from 20-week-old mice were immediately immersion fixed for transmission electron microscopic study. Compared to CKC, DBC exhibited US abnormalities characterized by mural endothelial cell tight and adherens ju...
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Papers by Melvin Hayden