Chih-pei Lin | National Yang Ming Chiao Tung University (original) (raw)

Papers by Chih-pei Lin

Research paper thumbnail of Bioactivity of CaO-SiO2 Based Ceramic Using in Endodonitcs

Objectives: Mineral trioxide aggregate, with the tricalcium silicate as the major component, is a... more Objectives: Mineral trioxide aggregate, with the tricalcium silicate as the major component, is a commercial material using for retrograde filling, perforation repair and vital pulp therapy in endodontics with promising results. However, several disadvantages of MTA have been reported such as long setting time, difficulty in handling, and the high arsenic levels contained. In this study, a pure CaO-SiO2 based ceramic (CSC) without toxic ingredients was developed. Methods: Briefly, three main components of MTA, C3S, C3A and C4AF, were produced via sintering process at high temperature and then mixed in the weight ratio of 8:1:1 respectively to obtain the pure CSC called M811. We further evaluated the hydration behavior and surface bioactivity of M811 to confirm its potential using in endodontic treatments. Results: Utilizing SEM, XRD and FT/IR, we found portlandite, calcite and calcium-silicate hydrated (CSH) were identified as the main products after hydration. In the hydrated M811,...

Research paper thumbnail of Direct Renin Inhibition with Aliskiren Improves Ischemia-Induced Neovasculogenesis in Diabetic Animals via the SDF-1 Related Mechanism

PloS one, 2015

Aliskiren is a direct renin inhibitor which is suggested to modify proangiogenic cells in additio... more Aliskiren is a direct renin inhibitor which is suggested to modify proangiogenic cells in addition to lower blood pressure. Given that angiogenesis is impaired in the presence of diabetes mellitus, we would like to investigate whether and how aliskiren enhances endothelial progenitor cells (EPCs) and improves ischemic-induced neovasculogenesis by an effect independent of blood pressure reduction in diabetic animals. Streptozotocin-induced diabetic mice were administered with either aliskiren (5 or 25 mg/kg/day) using an osmotic pump or hydralazine (2 or 10 mg/kg/day) given in drinking water for two weeks prior to a hind-limb ischemia surgery. Laser Doppler imaging and flow cytometry were used to evaluate the degree of neovasculogenesis and the circulating levels of EPCs, respectively. In streptozotocin-induced diabetic mice, aliskiren enhanced the recovery of limb perfusion and capillary density, increased the number of circulating Sca-1+/Flk-1+ EPC-like cells, and elevated the leve...

Research paper thumbnail of Clinical significance of Blastocystis hominis: experience from a medical center in northern Taiwan

Journal of microbiology, immunology, and infection = Wei mian yu gan ran za zhi, 2008

Blastocystis hominis is an intestinal protozoan. The pathogenic role of this organism in human be... more Blastocystis hominis is an intestinal protozoan. The pathogenic role of this organism in human beings is still controversial and has varied among reports from different geographic areas. The purpose of this study was to determine the clinical significance of B. hominis in northern Taiwan. A total of 100 patients who had a positive B. hominis stool examination during the period April to December of 2001 were retrospectively identified from Taipei Veterans General Hospital. The demographic and clinical characteristics of these patients were reviewed from the medical records. All of the patients were adults. Fifty nine patients had more than one underlying diseases, including malignancies. Twenty one patients presented with fever and 10 patients had gastrointestinal symptoms, including diarrhea and/or abdominal pain. However, all of the patients had other conditions that might have contributed to the clinical presentation, and they improved without specific treatment for B. hominis. Fu...

Research paper thumbnail of Clinical characteristics and endoscopic findings associated with Blastocystis hominis in healthy adults

The American journal of tropical medicine and hygiene, 2003

Ninety-nine individuals with stools positive for Blastocystis hominis but negative for other para... more Ninety-nine individuals with stools positive for Blastocystis hominis but negative for other parasites were identified from medical records of healthy adults who had received a physical examination at Taipei Veterans General Hospital from November 2000 to October 2002. The medical records of these 99 positive cases and 193 randomly selected controls, matched for age, sex, and date of examination, were retrospectively reviewed. The pathogenicity of B. hominis could not be demonstrated due to a lack of association with the development of gastrointestinal symptoms or pathologic findings on endoscopic examination. Multivariate analyses revealed that chronic hepatitis B infection was a predisposing condition to the acquisition of B. hominis (odd ratio = 2.848, 95% confidence interval = 1.299-6.242, P = 0.009), and concentration of urate was significantly lower in B. hominis-positive individuals (mean +/- SD = 361.64 +/- 87.44 versus 392.57 +/- 93.38 micromol/L; P = 0.009). Among the 64 i...

Research paper thumbnail of Endothelial progenitor cell dysfunction in cardiovascular diseases: Role of reactive oxygen species and inflammation

Research paper thumbnail of Correction: Intravenous Ferric Chloride Hexahydrate Supplementation Induced Endothelial Dysfunction and Increased Cardiovascular Risk among Hemodialysis Patients

Research paper thumbnail of Intravenous Ferric Chloride Hexahydrate Supplementation Induced Endothelial Dysfunction and Increased Cardiovascular Risk among Hemodialysis Patients

Research paper thumbnail of Inhibition of endothelial adhesion molecule expression by Monascus purpureus-fermented rice metabolites, monacolin K, ankaflavin, and monascin

Journal of the Science of Food and Agriculture, 2011

Research paper thumbnail of Monascus purpureus-fermented rice inhibits tumor necrosis factor-α-induced upregulation of matrix metalloproteinase 2 and 9 in human aortic smooth muscle cells

Journal of Pharmacy and Pharmacology, 2011

Inflammation is associated with atherosclerosis. Cholestin (Monascus purpureus-fermented rice) co... more Inflammation is associated with atherosclerosis. Cholestin (Monascus purpureus-fermented rice) contains a naturally occurring statin, which has lipid-modulating, anti-inflammatory and antioxidative effects. This study aimed to investigate the effects of Cholestin extract on the expression of matrix metalloproteinase (MMP)-2 and MMP-9 by tumor necrosis factor (TNF)-α-treated human aortic smooth muscle cells (HASMCs). Zymography, reverse transcription polymerase chain reaction and immunoblot analyses were used for analysis of MMP expression of TNF-α-stimulated HASMCs. Gel shift assay was used for analysis of transcription factor nuclear factor-κB (NF-κB) activation. Intracellular reactive oxygen species (ROS) generation was also analysed. The supplement of HASMCs with Cholestin extract significantly suppresses enzymatic activities of MMP-2 and MMP-9 in TNF-α-stimulated HASMCs. RT-PCR and immunoblot analyses show that Cholestin extract significantly attenuates TNF-α-induced mRNA and protein expressions of MMP-2 and MMP-9. Gel shift assays show that Cholestin treatment reduces TNF-α-activated NF-κB. Furthermore, Cholestin also attenuates intracellular ROS generation in TNF-α-treated HASMCs. The supplement with an ROS scavenger N-acetyl-cysteine (glutathione precursor) gives similar results to Cholestin. Cholestin reduces TNF-α-stimulated MMP-2 and MMP-9 expression as well as downregulating NF-κB activation and intracellular ROS formation in HASMCs, supporting the notion that the natural compound Cholestin may have potential application in clinical atherosclerosis disease.

Research paper thumbnail of Increased circulating CD31+/annexin V+ apoptotic microparticles and decreased circulating endothelial progenitor cell levels in hypertensive patients with microalbuminuria

Journal of Hypertension, 2010

Research paper thumbnail of Cholestin (Monascus purpureus rice) inhibits homocysteine-induced reactive oxygen species generation, nuclear factor-κB activation, and vascular cell adhesion molecule-1 expression in human aortic endothelial cells

Journal of Biomedical Science, 2008

Research paper thumbnail of Differential mononuclear cell activity and endothelial inflammation in coronary artery disease and cardiac syndrome X

International Journal of Cardiology, 2003

Research paper thumbnail of Anti-inflammatory strategies for homocysteine-related cardiovascular disease

Frontiers in Bioscience, 2009

Research paper thumbnail of Circulating mononuclear superoxide production and inflammatory markers for long-term prognosis in patients with cardiac syndrome X

Free Radical Biology and Medicine, 2006

Increased oxidative stress and vascular inflammation have been shown in patients with cardiac syn... more Increased oxidative stress and vascular inflammation have been shown in patients with cardiac syndrome X (CSX; angina, exercise-induced ischemia, and normal coronary angiogram). This study was conducted to assess the impact of basal superoxide generation by circulating mononuclear cells (MNCs), a contributor to intravascular oxidative stress, and serum inflammatory biomarkers, including high-sensitivity C-reactive protein, homocysteine, soluble intercellular adhesion molecule-1, soluble vascular adhesion molecule-1, and von Willebrand factor, on the long-term prognosis of CSX. During a mean follow-up of 31.5 +/- 14.2 months (maximum 5 years), a total of 12 events were recorded in 92 consecutive CSX patients. There were no deaths or myocardial infarctions, but 8 hospitalizations for acute coronary syndrome, 3 for stroke, and 1 for congestive heart failure due to left ventricular systolic dysfunction. Under univariate analysis, only basal superoxide generation by MNCs was associated with the risk for cardiovascular event. Based on multivariate analysis, basal superoxide generation by MNCs could still independently predict future events (relative risk for the highest compared to the lowest tertile, 3.87; 95% confidence interval, 1.42-10.54, p = 0.008). These findings demonstrate that long-term prognosis is fair in patients with CSX. Basal superoxide production of MNCs independently predicts future cardiovascular events, suggesting its potential role in measuring disease progression and risk stratification in these patients.

Research paper thumbnail of Predictors of inexplicable coronary artery spasm during coronary angiography in patients with stable angina — The role of intravascular oxidative stress

Clinical Biochemistry, 2009

Research paper thumbnail of Risk Stratification and Prognostic Implication of Plasma Biomarkers in Nondiabetic Patients With Stable Coronary Artery Disease *

CHEST Journal, 2004

To evaluate the implication of plasma biomarkers to future cardiovascular events in nondiabetic p... more To evaluate the implication of plasma biomarkers to future cardiovascular events in nondiabetic patients with stable coronary artery disease (CAD). Designs and settings: Prospective, follow-up study at a tertiary referral center. Patients and measurement: Serial plasma biomarkers including high-sensitivity C-reactive protein (hsCRP), homocysteine, soluble adhesion molecules, von Willebrand factor, and lipid profiles were determined before coronary angiograms in a series of nondiabetic CAD patients with stable angina. Among them, 75 consecutive patients who received coronary revascularization (48 coronary interventions and 27 coronary bypass surgeries) later and another 75 age- and gender-matched patients who preferred medical treatment were both enrolled. In patients of each group, major cardiovascular events including cardiac death, nonfatal myocardial infarction, new or repeated coronary revascularization, and hospitalization for unstable angina, stroke, or peripheral artery disease were prospectively followed up for at least 6 months. Patients were followed up to 40 months (median, 18 months). The incidences of major cardiovascular events were similar between the two groups. For patients with medical treatment, plasma levels of hsCRP, homocysteine, low-density lipoprotein, and the ratio of total cholesterol (TC) to high-density lipoprotein cholesterol (HDL-C) were significantly higher in those with cardiovascular events than those without. However, only hsCRP > 0.1 mg/dL (relative risk [RR], 2.78; 95% confidence interval [CI], 1.21 to 6.41; p = 0.016) and TC/HDL-C ratio > 4.8 (RR, 2.42; 95% CI, 1.04 to 5.65; p = 0.041) were independent predictors by multivariable analysis. For patients with revascularization, basal plasma hsCRP levels were higher in those with cardiovascular events than those without (p = 0.04). However, no biochemical markers could predict future major cardiovascular events in these patients. In nondiabetic patients with CAD, basal plasma hsCRP levels were increased with future cardiovascular events regardless of different treatment strategies. Both plasma hsCRP level and TC/HDL-C ratio independently predict future cardiovascular events, confirming the role of plasma biomarkers in clinical risk stratification especially in patients with medical treatment.

Research paper thumbnail of Far infra-red therapy promotes ischemia-induced angiogenesis in diabetic mice and restores high glucose-suppressed endothelial progenitor cell functions

Cardiovascular Diabetology, 2012

Research paper thumbnail of THE EFFECT OF COMPOSITION CHANGE IN SOL-GEL SYNTHESIZED PSC

Biomedical Engineering: Applications, Basis and Communications, 2008

Research paper thumbnail of Moderate intake of red wine improves ischemia-induced neovascularization in diabetic mice—Roles of endothelial progenitor cells and nitric oxide

Research paper thumbnail of Niacin improves ischemia-induced neovascularization in diabetic mice by enhancement of endothelial progenitor cell functions independent of changes in plasma lipids

Research paper thumbnail of Bioactivity of CaO-SiO2 Based Ceramic Using in Endodonitcs

Objectives: Mineral trioxide aggregate, with the tricalcium silicate as the major component, is a... more Objectives: Mineral trioxide aggregate, with the tricalcium silicate as the major component, is a commercial material using for retrograde filling, perforation repair and vital pulp therapy in endodontics with promising results. However, several disadvantages of MTA have been reported such as long setting time, difficulty in handling, and the high arsenic levels contained. In this study, a pure CaO-SiO2 based ceramic (CSC) without toxic ingredients was developed. Methods: Briefly, three main components of MTA, C3S, C3A and C4AF, were produced via sintering process at high temperature and then mixed in the weight ratio of 8:1:1 respectively to obtain the pure CSC called M811. We further evaluated the hydration behavior and surface bioactivity of M811 to confirm its potential using in endodontic treatments. Results: Utilizing SEM, XRD and FT/IR, we found portlandite, calcite and calcium-silicate hydrated (CSH) were identified as the main products after hydration. In the hydrated M811,...

Research paper thumbnail of Direct Renin Inhibition with Aliskiren Improves Ischemia-Induced Neovasculogenesis in Diabetic Animals via the SDF-1 Related Mechanism

PloS one, 2015

Aliskiren is a direct renin inhibitor which is suggested to modify proangiogenic cells in additio... more Aliskiren is a direct renin inhibitor which is suggested to modify proangiogenic cells in addition to lower blood pressure. Given that angiogenesis is impaired in the presence of diabetes mellitus, we would like to investigate whether and how aliskiren enhances endothelial progenitor cells (EPCs) and improves ischemic-induced neovasculogenesis by an effect independent of blood pressure reduction in diabetic animals. Streptozotocin-induced diabetic mice were administered with either aliskiren (5 or 25 mg/kg/day) using an osmotic pump or hydralazine (2 or 10 mg/kg/day) given in drinking water for two weeks prior to a hind-limb ischemia surgery. Laser Doppler imaging and flow cytometry were used to evaluate the degree of neovasculogenesis and the circulating levels of EPCs, respectively. In streptozotocin-induced diabetic mice, aliskiren enhanced the recovery of limb perfusion and capillary density, increased the number of circulating Sca-1+/Flk-1+ EPC-like cells, and elevated the leve...

Research paper thumbnail of Clinical significance of Blastocystis hominis: experience from a medical center in northern Taiwan

Journal of microbiology, immunology, and infection = Wei mian yu gan ran za zhi, 2008

Blastocystis hominis is an intestinal protozoan. The pathogenic role of this organism in human be... more Blastocystis hominis is an intestinal protozoan. The pathogenic role of this organism in human beings is still controversial and has varied among reports from different geographic areas. The purpose of this study was to determine the clinical significance of B. hominis in northern Taiwan. A total of 100 patients who had a positive B. hominis stool examination during the period April to December of 2001 were retrospectively identified from Taipei Veterans General Hospital. The demographic and clinical characteristics of these patients were reviewed from the medical records. All of the patients were adults. Fifty nine patients had more than one underlying diseases, including malignancies. Twenty one patients presented with fever and 10 patients had gastrointestinal symptoms, including diarrhea and/or abdominal pain. However, all of the patients had other conditions that might have contributed to the clinical presentation, and they improved without specific treatment for B. hominis. Fu...

Research paper thumbnail of Clinical characteristics and endoscopic findings associated with Blastocystis hominis in healthy adults

The American journal of tropical medicine and hygiene, 2003

Ninety-nine individuals with stools positive for Blastocystis hominis but negative for other para... more Ninety-nine individuals with stools positive for Blastocystis hominis but negative for other parasites were identified from medical records of healthy adults who had received a physical examination at Taipei Veterans General Hospital from November 2000 to October 2002. The medical records of these 99 positive cases and 193 randomly selected controls, matched for age, sex, and date of examination, were retrospectively reviewed. The pathogenicity of B. hominis could not be demonstrated due to a lack of association with the development of gastrointestinal symptoms or pathologic findings on endoscopic examination. Multivariate analyses revealed that chronic hepatitis B infection was a predisposing condition to the acquisition of B. hominis (odd ratio = 2.848, 95% confidence interval = 1.299-6.242, P = 0.009), and concentration of urate was significantly lower in B. hominis-positive individuals (mean +/- SD = 361.64 +/- 87.44 versus 392.57 +/- 93.38 micromol/L; P = 0.009). Among the 64 i...

Research paper thumbnail of Endothelial progenitor cell dysfunction in cardiovascular diseases: Role of reactive oxygen species and inflammation

Research paper thumbnail of Correction: Intravenous Ferric Chloride Hexahydrate Supplementation Induced Endothelial Dysfunction and Increased Cardiovascular Risk among Hemodialysis Patients

Research paper thumbnail of Intravenous Ferric Chloride Hexahydrate Supplementation Induced Endothelial Dysfunction and Increased Cardiovascular Risk among Hemodialysis Patients

Research paper thumbnail of Inhibition of endothelial adhesion molecule expression by Monascus purpureus-fermented rice metabolites, monacolin K, ankaflavin, and monascin

Journal of the Science of Food and Agriculture, 2011

Research paper thumbnail of Monascus purpureus-fermented rice inhibits tumor necrosis factor-α-induced upregulation of matrix metalloproteinase 2 and 9 in human aortic smooth muscle cells

Journal of Pharmacy and Pharmacology, 2011

Inflammation is associated with atherosclerosis. Cholestin (Monascus purpureus-fermented rice) co... more Inflammation is associated with atherosclerosis. Cholestin (Monascus purpureus-fermented rice) contains a naturally occurring statin, which has lipid-modulating, anti-inflammatory and antioxidative effects. This study aimed to investigate the effects of Cholestin extract on the expression of matrix metalloproteinase (MMP)-2 and MMP-9 by tumor necrosis factor (TNF)-α-treated human aortic smooth muscle cells (HASMCs). Zymography, reverse transcription polymerase chain reaction and immunoblot analyses were used for analysis of MMP expression of TNF-α-stimulated HASMCs. Gel shift assay was used for analysis of transcription factor nuclear factor-κB (NF-κB) activation. Intracellular reactive oxygen species (ROS) generation was also analysed. The supplement of HASMCs with Cholestin extract significantly suppresses enzymatic activities of MMP-2 and MMP-9 in TNF-α-stimulated HASMCs. RT-PCR and immunoblot analyses show that Cholestin extract significantly attenuates TNF-α-induced mRNA and protein expressions of MMP-2 and MMP-9. Gel shift assays show that Cholestin treatment reduces TNF-α-activated NF-κB. Furthermore, Cholestin also attenuates intracellular ROS generation in TNF-α-treated HASMCs. The supplement with an ROS scavenger N-acetyl-cysteine (glutathione precursor) gives similar results to Cholestin. Cholestin reduces TNF-α-stimulated MMP-2 and MMP-9 expression as well as downregulating NF-κB activation and intracellular ROS formation in HASMCs, supporting the notion that the natural compound Cholestin may have potential application in clinical atherosclerosis disease.

Research paper thumbnail of Increased circulating CD31+/annexin V+ apoptotic microparticles and decreased circulating endothelial progenitor cell levels in hypertensive patients with microalbuminuria

Journal of Hypertension, 2010

Research paper thumbnail of Cholestin (Monascus purpureus rice) inhibits homocysteine-induced reactive oxygen species generation, nuclear factor-κB activation, and vascular cell adhesion molecule-1 expression in human aortic endothelial cells

Journal of Biomedical Science, 2008

Research paper thumbnail of Differential mononuclear cell activity and endothelial inflammation in coronary artery disease and cardiac syndrome X

International Journal of Cardiology, 2003

Research paper thumbnail of Anti-inflammatory strategies for homocysteine-related cardiovascular disease

Frontiers in Bioscience, 2009

Research paper thumbnail of Circulating mononuclear superoxide production and inflammatory markers for long-term prognosis in patients with cardiac syndrome X

Free Radical Biology and Medicine, 2006

Increased oxidative stress and vascular inflammation have been shown in patients with cardiac syn... more Increased oxidative stress and vascular inflammation have been shown in patients with cardiac syndrome X (CSX; angina, exercise-induced ischemia, and normal coronary angiogram). This study was conducted to assess the impact of basal superoxide generation by circulating mononuclear cells (MNCs), a contributor to intravascular oxidative stress, and serum inflammatory biomarkers, including high-sensitivity C-reactive protein, homocysteine, soluble intercellular adhesion molecule-1, soluble vascular adhesion molecule-1, and von Willebrand factor, on the long-term prognosis of CSX. During a mean follow-up of 31.5 +/- 14.2 months (maximum 5 years), a total of 12 events were recorded in 92 consecutive CSX patients. There were no deaths or myocardial infarctions, but 8 hospitalizations for acute coronary syndrome, 3 for stroke, and 1 for congestive heart failure due to left ventricular systolic dysfunction. Under univariate analysis, only basal superoxide generation by MNCs was associated with the risk for cardiovascular event. Based on multivariate analysis, basal superoxide generation by MNCs could still independently predict future events (relative risk for the highest compared to the lowest tertile, 3.87; 95% confidence interval, 1.42-10.54, p = 0.008). These findings demonstrate that long-term prognosis is fair in patients with CSX. Basal superoxide production of MNCs independently predicts future cardiovascular events, suggesting its potential role in measuring disease progression and risk stratification in these patients.

Research paper thumbnail of Predictors of inexplicable coronary artery spasm during coronary angiography in patients with stable angina — The role of intravascular oxidative stress

Clinical Biochemistry, 2009

Research paper thumbnail of Risk Stratification and Prognostic Implication of Plasma Biomarkers in Nondiabetic Patients With Stable Coronary Artery Disease *

CHEST Journal, 2004

To evaluate the implication of plasma biomarkers to future cardiovascular events in nondiabetic p... more To evaluate the implication of plasma biomarkers to future cardiovascular events in nondiabetic patients with stable coronary artery disease (CAD). Designs and settings: Prospective, follow-up study at a tertiary referral center. Patients and measurement: Serial plasma biomarkers including high-sensitivity C-reactive protein (hsCRP), homocysteine, soluble adhesion molecules, von Willebrand factor, and lipid profiles were determined before coronary angiograms in a series of nondiabetic CAD patients with stable angina. Among them, 75 consecutive patients who received coronary revascularization (48 coronary interventions and 27 coronary bypass surgeries) later and another 75 age- and gender-matched patients who preferred medical treatment were both enrolled. In patients of each group, major cardiovascular events including cardiac death, nonfatal myocardial infarction, new or repeated coronary revascularization, and hospitalization for unstable angina, stroke, or peripheral artery disease were prospectively followed up for at least 6 months. Patients were followed up to 40 months (median, 18 months). The incidences of major cardiovascular events were similar between the two groups. For patients with medical treatment, plasma levels of hsCRP, homocysteine, low-density lipoprotein, and the ratio of total cholesterol (TC) to high-density lipoprotein cholesterol (HDL-C) were significantly higher in those with cardiovascular events than those without. However, only hsCRP > 0.1 mg/dL (relative risk [RR], 2.78; 95% confidence interval [CI], 1.21 to 6.41; p = 0.016) and TC/HDL-C ratio > 4.8 (RR, 2.42; 95% CI, 1.04 to 5.65; p = 0.041) were independent predictors by multivariable analysis. For patients with revascularization, basal plasma hsCRP levels were higher in those with cardiovascular events than those without (p = 0.04). However, no biochemical markers could predict future major cardiovascular events in these patients. In nondiabetic patients with CAD, basal plasma hsCRP levels were increased with future cardiovascular events regardless of different treatment strategies. Both plasma hsCRP level and TC/HDL-C ratio independently predict future cardiovascular events, confirming the role of plasma biomarkers in clinical risk stratification especially in patients with medical treatment.

Research paper thumbnail of Far infra-red therapy promotes ischemia-induced angiogenesis in diabetic mice and restores high glucose-suppressed endothelial progenitor cell functions

Cardiovascular Diabetology, 2012

Research paper thumbnail of THE EFFECT OF COMPOSITION CHANGE IN SOL-GEL SYNTHESIZED PSC

Biomedical Engineering: Applications, Basis and Communications, 2008

Research paper thumbnail of Moderate intake of red wine improves ischemia-induced neovascularization in diabetic mice—Roles of endothelial progenitor cells and nitric oxide

Research paper thumbnail of Niacin improves ischemia-induced neovascularization in diabetic mice by enhancement of endothelial progenitor cell functions independent of changes in plasma lipids