Vascular proliferation and transforming growth factor-beta expression in pre- and early stage of diabetes mellitus in Otsuka Long-Evans Tokushima fatty rats

Role of AMP deaminase in diabetic cardiomyopathy

Diabetes mellitus is one of the major causes of ischemic and nonischemic heart failure. While hypertension and coronary artery disease are frequent comorbidities in patients with diabetes, cardiac contractile dysfunction and remodeling occur in diabetic patients even without comorbidities, which is referred to as diabetic cardiomyopathy. Investigations in recent decades have demonstrated that the production of reactive oxygen species (ROS), impaired handling of intracellular Ca2+, and alterations in energy metabolism are involved in the development of diabetic cardiomyopathy. AMP deaminase (AMPD) directly regulates adenine nucleotide metabolism and energy transfer by adenylate kinase and indirectly modulates xanthine oxidoreductase-mediated pathways and AMP-activated protein kinase-mediated signaling. Upregulation of AMPD in diabetic hearts was first reported more than 30 years ago, and subsequent studies showed similar upregulation in the liver and skeletal muscle. Evidence for the roles of AMPD in diabetes-induced fatty liver, sarcopenia, and heart failure has been accumulating. A series of our recent studies showed that AMPD localizes in the mitochondria-associated endoplasmic reticulum membrane as well as the sarcoplasmic reticulum and cytosol and participates in the regulation of mitochondrial Ca2+ and suggested that upregulated AMPD contributes to contractile dysfunction in diabetic cardiomyopathy via increased generation of ROS, adenine nucleotide depletion, and impaired mitochondrial respiration. The detrimental effects of AMPD were manifested at times of increased cardiac workload by pressure loading. In this review, we briefly summarize the expression and functions of AMPD in the heart and discuss the roles of AMPD in diabetic cardiomyopathy, mainly focusing on contractile dysfunction caused by this disorder.

Effects of aging and type 2 diabetes on cardiac structure and function: Underlying mechanisms

We characterized long-term changes in cardiac structure and function in a high-fat diet/streptozotocin mouse model of aging and type 2 diabetes mellitus (T2D) and examined how the intersection of both conditions alters plasma metabolomics. We also evaluated the possible roles played by oxidative stress, arginase activity and pro-inflammatory cytokines. C57BL/6 male mice (13-month-old) were used. Control animals (n = 13) were fed regular chow for 10 months (aged group). T2D animals (n = 25) were provided a single injection of streptozotocin and fed a high fat diet for 10 months. In select endpoints, young animals were used for comparison. To monitor changes in left ventricular (LV) structure and function, echocardiography was used. At the terminal study (23 months), blood was collected and hearts processed for biochemical or histological analysis. Echo yielded diminished diastolic function with aging and T2D. LV fractional shortening and ejection fraction decreased with T2D by 16 months peaking at 23 months. Western blots noted increases in fibronectin and type I collagen with aging/T2D and greater levels with T2D in α-smooth muscle actin. Increases in plasma and/or myocardial protein carbonyls, arginase activity and pro-inflammatory cytokines occurred with aging and T2D. Untargeted metabolomics and cheminformatics revealed differences in the plasma metabolome of T2D vs. aged mice while select classes of lipid metabolites linked to insulin resistance, were dysregulated. We thus, document changes in LV structure and function with aging that in select endpoints, are accentuated with T2D and link them to increases in OS, arginase activity and pro-inflammatory cytokines.

Hemodynamic response during hyperbaric treatment on skeletal muscle in a type 2 diabetes rat model

Mild hyperbaric treatment prevents type 2 diabetes progression due to increased oxygen concentration and blood flow in skeletal muscle. However, it remains unknown whether this treatment is effective during all stages of type 2 diabetes. This study aimed to investigate the influences of hyperbaric treatment at 1.3 atmospheres absolute (ATA) on hemodynamic response in various stages of type 2 diabetes. Otsuka Long-Evans Tokushima fatty (OLETF) and Long-Evans Tokushima Otsuka (LETO) rats were used as models of type 2 diabetes and healthy controls, respectively. Glucose levels were significantly higher in OLETF rats than in LETO rats at all ages. Glucose intolerance gradually increased with age in OLETF rats. Insulin levels in OLETF rats were significantly higher at 20-week-old, however, were significantly lower at 60-week-old than in LETO rats. Oxy-Hb, total Hb, and StO₂ in skeletal muscle were increased during hyperbaric treatment in both rats. The hemodynamic changes were significantly higher in OLETF rats than LETO rats, and those changes were also pronounced at 8-week-old compared with other age in OLETF rats. These results suggest that hyperbaric treatment at 1.3 ATA acts on pathophysiological factors and the efficacy could be found only in the early stage of type 2 diabetes.

Effects of insulin on the proliferation and global gene expression profile of A7r5 cells

Insulin contributes to atherosclerosis, but the potential mechanisms are kept unclear. In this study, insulin promoted proliferation of A7r5 cells. Microarray analysis indicated that insulin significantly changed 812 probe sets of genes, including 405 upregulated and 407 downregulated ones (fold change ≥ 1.5 or ≤ - 1.5; p < 0.05). Gene ontology analysis showed that the differentially expressed genes were involved in a number of processes, including the regulation of cell proliferation/migration/cycle, apoptotic process, oxidative stress, inflammatory response, mitogen-activated protein kinase (MAPK) activity, lipid metabolic process and extracellular matrix organization. Moreover, Kyoto Encyclopedia of Genes and Genomes pathway analysis indicated that the genes were involved in biosynthesis of amino acids, fatty acid metabolism, glycolysis/gluconeogenesis, metabolic pathways, regulation of autophagy, cell cycle and apoptosis, as well as the PI3K-Akt, MAPK, mTOR and NF-κB signaling pathways. Additionally, insulin enhanced phosphorylation of MAPK kinase 1/2 and Akt, suggesting activation of the MAPK and PI3K-Akt signaling pathways. Inhibition of ERK1/2 reduced insulin-induced proliferation. This study revealed the proliferative effects of insulin and displayed global gene expression profile of A7r5 cells stimulated by insulin, suggesting new insight into the molecular pathogenesis of insulin promoting atherosclerosis.

Increased aortic stiffness index in patients with type 1 diabetes without cardiovascular disease compared to controls

PURPOSE

Increased arterial stiffness is an early sign of endothelial dysfunction. Nevertheless, measures of the elastic properties of the aortic root in patients with type 1 diabetes are still lacking. The aim of this study was to compare aortic root stiffness index in type 1 diabetes and healthy controls.

METHODS

Ninety-three patients with type 1 diabetes without cardiovascular diseases were recruited and compared to 33 healthy controls. Aortic root elastic properties were estimated by measuring the systolic and diastolic diameters on M-mode acquisition.

RESULTS

None of the subjects showed alterations of either systolic or diastolic echocardiographic parameters. Patients with type 1 diabetes had a very low prevalence of chronic complications and their metabolic control was good. Significantly increased aortic stiffness index was found in type 1 diabetes compared to controls, and the same different pattern was found in men and women. The presence of type 1 diabetes and increased pulse pressure was significantly associated with aortic stiffness index in a multivariate linear analysis.

CONCLUSION

This study strongly suggests that patients with type 1 diabetes develop aortic root stiffness in the absence of cardiovascular diseases. This alteration may be part of a more generalized arterial dysfunction in type 1 diabetes.

Expression of Natural Cytotoxicity Receptors on and Intracellular Cytokine Production by NK Cells in Women with Gestational Diabetes Mellitus

PROBLEM

To determine the role of peripheral blood NK (pNK) cells in putative etiology of gestational diabetes, the expression of surface markers on pNK cells and the percentage of cytokine-producing pNK cells in women at 12 weeks of pregnancy with gestational diabetes mellitus (GDM) were studied.

METHOD OF STUDY

Multicolor flow cytometry was used to analyze the expression of NK cell surface receptors (CD16, NKp46, and NKp30) and intracellular cytokines (IFN-γ, TNF-α, TGF-β, and VEGF) in pNK cells (CD56(dim) and CD56(bright) ) at 12 weeks of pregnancy with GDM (n = 7) and non-GDM (n = 28).

RESULTS

CD56(bright) /CD16(-) NK and CD56(bright) /NKp46(+) NK cell percentage were significantly lower in GDM women than that in non-GDM women. IFN-γ- and TNF-α-producing CD56(+) cells, respectively, were significantly high, while TGF-β- and VEGF-producing CD56(+) cells and CD56(bright) cells, respectively, were significantly low in GDM women.

CONCLUSIONS

Women with GDM possibly have abnormal NK cell function for the expression of surface receptors and cytokine production.

Localized micro- and nano-scale remodelling in the diabetic aorta

Diabetes is strongly associated with cardiovascular disease, but the mechanisms, structural and biomechanical consequences of aberrant blood vessel remodelling remain poorly defined. Using an experimental (streptozotocin, STZ) rat model of diabetes, we hypothesized that diabetes enhances extracellular protease activity in the aorta and induces morphological, compositional and localized micromechanical tissue remodelling. We found that the medial aortic layer underwent significant thickening in diabetic animals but without significant changes in collagen or elastin (abundance). Scanning acoustic microscopy demonstrated that such tissue remodelling was associated with a significant decrease in acoustic wave speed (an indicator of reduced material stiffness) in the inter-lamellar spaces of the vessel wall. This index of decreased stiffness was also linked to increased extracellular protease activity (assessed by semi-quantitative in situ gelatin zymography). Such a proteolytically active environment may affect the macromolecular structure of long-lived extracellular matrix molecules. To test this hypothesis, we also characterized the effects of diabetes on the ultrastructure of an important elastic fibre component: the fibrillin microfibril. Using size exclusion chromatography and atomic force microscopy, we isolated and imaged microfibrils from both healthy and diabetic aortas. Microfibrils derived from diabetic tissues were fragmented, morphologically disrupted and weakened (as assessed following molecular combing). These structural and functional abnormalities were not replicated by in vitro glycation. Our data suggest that proteolysis may be a key driver of localized mechanical change in the inter-lamellar space of diabetic rat aortas and that structural proteins (such as fibrillin microfbrils) may be biomarkers of diabetes induced damage.

Hemoglobin A(1c) in nondiabetic patients: an independent predictor of coronary artery disease and its severity

OBJECTIVE

To examine the association between hemoglobin A(1c) (HbA(1c)) and the presence, severity, and complexity of angiographically proven coronary artery disease (CAD) in nondiabetic patients.

PATIENTS AND METHODS

We performed a single-center, observational, cross-sectional study of 1141 consecutive nondiabetic patients who underwent coronary angiography from January 1, 2011, through December 31, 2011. The study population was divided into 4 interquartiles according to HbA(1c) levels (<5.5%, 5.5%-5.7%, 5.8%-6.1%, and >6.1%).

RESULTS

Patients with higher HbA(1c) levels tended to be older, overweight, and hypertensive, had higher blood glucose levels, and had lower glomerular filtration rates. Higher HbA(1c) levels were associated in a graded fashion with the presence of CAD, disease severity (higher number of diseased vessels and presence of left main and/or triple vessel disease), and disease complexity (higher SYNTAX score, higher number of patients in intermediate or high SYNTAX tertiles, coronary calcium, and chronic total occlusions). After adjustment for major conventional cardiovascular risk factors, compared with patients with HbA(1c) levels less than 5.5%, the odds ratios of occurrence of CAD in the HbA(1c) quartiles of 5.5% to 5.7%, 5.8% to 6.1%, and greater than 6.1% were 1.8 (95% CI, 1.2-2.7), 3.5 (95% CI, 2.3-5.3), and 4.9 (95% CI, 3.0-8.1), respectively.

CONCLUSION

The HbA(1c) level has a linear incremental association with CAD in nondiabetic individuals. The HbA(1c) level is also independently correlated with disease severity and higher SYNTAX scores. Thus, HbA(1c) measurement could be used to improve cardiovascular risk assessment in nondiabetic individuals.

Bekhit A. Anti-diabetic activity of red pitaya (Hylocereus polyrhizus) fruit

This study investigated the anti-diabetic activity of red pitaya (Hylocereus polyrhizus) fruit.

Vascular aldosterone production at the pre-diabetic stage of young Otsuka Long-Evans Tokushima Fatty (OLETF) rats, compared with Long-Evans Tokushima Otsuka (LETO) rats

We examined the ability of aortic smooth muscle cells (AoSMC) prepared from spontaneously diabetic rats to produce aldosterone (Aldo) and the regulatory mechanism that controls their Aldo production. AoSMC of 6 week-old Long-Evans Tokushima Otsuka (LETO: the control group) and 6 week-old Otsuka Long-Evans Tokushima Fatty (OLETF: the type 2 diabetes group) rats were used in the present experiments. CYP11B2 (Aldo synthetase) mRNA expression was detected in both the LETO and OLETF AoSMC. Basal Aldo production was significantly greater (4-5 fold higher) in the OLETF AoSMC culture medium than in the LETO AoSMC culture medium. When AoSMC were co-incubated with high-density lipoproteins (HDL), supplying cholesterol as a substrate for steroidogenesis in rats, angiotensin II (AII) significantly increased greater Aldo production in the OLETF AoSMC than in the LETO AoSMC. The present data suggested that future onset of diabetic vascular dysfunction is partly caused by excess Aldo production by AoSMC in young OLETF rats. Concomitant stimulation by HDL and AII resulted in elevated Aldo production in the OLETF and the LETO AoSMC, and also demonstrated that AII-induced Aldo production is greatly enhanced by HDL in OLETF, rather than in LETO. In conclusion, our data clearly demonstrated that Aldo production in the OLETF AoSMC was significantly higher than in the LETO AoSMC, suggesting possible future onset of vascular dysfunction in diabetes, induced by local Aldo production in the AoSMC.

Myocardial tissue remodeling in adolescent obesity

BACKGROUND

Childhood obesity is a significant risk factor for cardiovascular disease in adulthood. Although ventricular remodeling has been reported in obese youth, early tissue-level markers within the myocardium that precede organ-level alterations have not been described.

METHODS AND RESULTS

We studied 21 obese adolescents (mean age, 17.7±2.6 years; mean body mass index [BMI], 41.9±9.5 kg/m(2), including 11 patients with type 2 diabetes [T2D]) and 12 healthy volunteers (age, 15.1±4.5 years; BMI, 20.1±3.5 kg/m(2)) using biomarkers of cardiometabolic risk and cardiac magnetic resonance imaging (CMR) to phenotype cardiac structure, function, and interstitial matrix remodeling by standard techniques. Although left ventricular ejection fraction and left atrial volumes were similar in healthy volunteers and obese patients (and within normal body size-adjusted limits), interstitial matrix expansion by CMR extracellular volume fraction (ECV) was significantly different between healthy volunteers (median, 0.264; interquartile range [IQR], 0.253 to 0.271), obese adolescents without T2D (median, 0.328; IQR, 0.278 to 0.345), and obese adolescents with T2D (median, 0.376; IQR, 0.336 to 0.407; P=0.0001). ECV was associated with BMI for the entire population (r=0.58, P<0.001) and with high-sensitivity C-reactive protein (r=0.47, P<0.05), serum triglycerides (r=0.51, P<0.05), and hemoglobin A1c (r=0.76, P<0.0001) in the obese stratum.

CONCLUSIONS

Obese adolescents (particularly those with T2D) have subclinical alterations in myocardial tissue architecture associated with inflammation and insulin resistance. These alterations precede significant left ventricular hypertrophy or decreased cardiac function.

Central arterial aging and the epidemic of systolic hypertension and atherosclerosis

The structure and function of central arteries change throughout the lifetime of humans and animals. Since atherosclerosis and hypertension are prevalent in epidemic proportion among older persons, it is reasonable to hypothesize that specific mechanisms that underlie the arterial substrate that has been altered by an "aging process" are intimately linked to arterial diseases. Indeed, recent studies reveal a profile of arterial cell and matrix properties that emerges with advancing age within the grossly normal appearing aortic wall of both animals and humans. This profile is proinflammatory, and is manifested by intimal infiltration of fetal cells, increased production of angiotensin II (Ang II)-signaling pathway molecules, eg, matrix metalloproteases (MMPs), and monocyte chemoattractant protein (MCP-1), transforming growth factor B1 (TGF-beta1), enhanced activation of MMPs, TGF-beta, and NADPH oxidase, and reduced nitric oxide (NO) bioavailability. This profile is similar to that induced at younger ages in experimental animal models of hypertension or atherosclerosis. In humans, this proinflammatory state, which occurs in the absence of lipid deposition, appears to be attributable to aging, per se. Other well known human risk factors, eg, altered lipid metabolism, smoking, and lack of exercise, interact with this arterial substrate that is altered by aging and render the aging human artery fertile soil for facilitation of the initiation and progression of arterial diseases. Therapies to reduce or retard this age-associated proinflammatory state within the grossly appearing arterial wall central arteries, in addition to slowing arterial aging, per se, may have a substantial impact on the quintessential age-associated arterial diseases of our society.

Effect of ginsam, a vinegar extract from Panax ginseng, on body weight and glucose homeostasis in an obese insulin-resistant rat model

Extracts of ginseng species show antihyperglycemic activity. We evaluated the antihyperglycemic and antiobesity effects of ginsam, a component of Panax ginseng produced by vinegar extraction, which is enriched in the ginsenoside Rg3. Otsuka Long-Evans Tokushima Fatty rats, an obese insulin-resistant rat model, were assigned into 1 of 3 groups (n = 8 each): controls (isotonic sodium chloride solution, 5 mL/d), rats given 300 mg/(kg d) ginsam, and rats given 500 mg/(kg d) ginsam. An intraperitoneal 2-hour glucose tolerance test was performed at the end of the 6-week treatment. After 8 weeks, body and liver weights, visceral fat measured by computed tomography, and fasting glucose and insulin concentrations and lipid profiles were recorded. Insulin-resistant rats treated with ginsam had lower fasting and postprandial glucose concentrations compared with vehicle-treated rats. Importantly, overall glucose excursion during the intraperitoneal 2-hour glucose tolerance test decreased by 21.5% (P < .01) in the treated rats, indicating improved glucose tolerance. Plasma insulin concentration was significantly lower in ginsam-treated rats. These changes may be related to increased glucose transporter 4 expression in skeletal muscle. Interestingly, when the data from both ginsam-treated groups were combined, body weight was 60% lower in the ginsam-treated rats than in the controls (P < .01). Liver weight and serum alanine aminotransferase concentrations were also lower in the ginsam-treated rats. These effects were associated with increased peroxisome proliferator-activated receptor gamma expression and adenosine monophosphate-activated protein kinase phosphorylation in liver and muscle. Our data suggest that ginsam has distinct beneficial effects on glucose metabolism and body weight control in an obese animal model of insulin resistance by changing the expression of genes involved in glucose and fatty acid metabolism.

Role of protein O-linked N-acetyl-glucosamine in mediating cell function and survival in the cardiovascular system

There is growing recognition that the O-linked attachment of N-acetyl-glucosamine (O-GlcNAc) on serine and threonine residues of nuclear and cytoplasmic proteins is a highly dynamic post-translational modification that plays a key role in signal transduction pathways. Numerous proteins have been identified as targets of O-GlcNAc modifications including kinases, phosphatases, transcription factors, metabolic enzymes, chaperons, and cytoskeletal proteins. Modulation of O-GlcNAc levels has been shown to modify DNA binding, enzyme activity, protein-protein interactions, the half-life of proteins, and subcellular localization. The level of O-GlcNAc is regulated in part by the metabolism of glucose via the hexosamine biosynthesis pathway (HBP), and the metabolic abnormalities associated with insulin resistance and diabetes, such as hyperglycemia, hyperlipidemia, and hyperinsulinemia, are all associated with increased flux through the HBP and elevated O-GlcNAc levels. Increased HBP flux and O-GlcNAc levels have been implicated in the impaired relaxation of isolated cardiomyocytes, blunted response to angiotensin II and phenylephrine, hyperglycemia-induced cardiomyocyte apoptosis, and endothelial and vascular cell dysfunction. In contrast to these adverse effects, recent studies have also shown that O-GlcNAc levels increase in response to acute stress and that this is associated with increased cell survival. Thus, while the relationship between O-GlcNAc levels and cellular function is complex and not well-understood, it is clear that these pathways play a critical role in the regulation of cell function and survival in the cardiovascular system and may be implicated in the adverse effects of metabolic disease on the heart.

Increased aortic stiffness in the insulin-resistant Zuckerfa/farat

Accumulating clinical evidence indicates increased aortic stiffness, an independent risk factor for cardiovascular and all-cause mortality, in type 2 diabetic and glucose-intolerant individuals. The present study sought to determine whether increased mechanical stiffness, an altered extracellular matrix, and a profibrotic gene expression profile could be observed in the aorta of the insulin-resistant Zucker fa/fa rat. Mechanical testing of Zucker fa/fa aortas showed increased vascular stiffness in longitudinal and circumferential directions compared with Zucker lean controls. Unequal elevations in developed strain favoring the longitudinal direction resulted in a loss of anisotropy. Real-time quantitative PCR and immunohistochemistry revealed increased expression of fibronectin and collagen IVα3in the Zucker fa/fa aorta. In addition, expression of transforming growth factor-β and several Smad proteins was increased in vessels from insulin-resistant animals. In rat vascular smooth muscle cells, 12–18 h of exposure to insulin (100 nmol/l) enhanced transforming growth factor-β1 mRNA expression, implicating a role for hyperinsulinemia in vascular stiffness. Thus there is mechanical, structural, and molecular evidence of arteriosclerosis in the Zucker fa/fa rat at the glucose-intolerant, hyperinsulinemic stage.

The melanocortin agonist melanotan II increases insulin sensitivity in OLETF rats

Effects of peripheral administration of melanotan II (MTII), a melanocortin agonist, on insulin sensitivity and glucose tolerance were examined in Otsuka Long-Evans Tokushima Fatty (OLETF) rats. Subcutaneous administration of MTII with osmotic mini-pumps decreased food intake and body weight in OLETF rats. MTII group showed more sensitivity to insulin compared with that allowed to eat ad libitum or pair-fed group in insulin tolerance tests on day 9. MTII group also showed significantly lower glucose values than ad libitum group in glucose tolerance tests on days 11 and 23. Thus, MTII increased insulin sensitivity and improved glucose tolerance in OLETF rats.

Transforming growth factor beta at clinical onset of Type 1 diabetes mellitus. A pilot study

AIMS

The aims of the study were to determine whether transforming growth factor beta1 TGF-beta1 levels are raised at diagnosis of Type 1 diabetes mellitus and are related to blood glucose.

SUBJECTS AND METHODS

Fourteen patients (mean age 24.3 +/- 4.9 years) admitted to hospital for onset of Type 1 diabetes were studied. On the first day of hospitalization, before insulin therapy, and at 1, 4 and 16 weeks, fasting blood glucose, HbA(1c), lipid profile and TGF-beta1 levels and TGF-beta1 levels in 24-h urine were determined. The control group included 14 non-diabetic subjects with similar characteristics to those of the diabetic group.

RESULTS

Plasma and urinary TGF-beta1 levels were significantly lower in controls (4.7 (1.6-6.8) ng/ml P < 0.001; 5.7 (1.5-8.5) ng/mg urinary creatinine, P < 0.01) than in patients with Type 1 diabetes mellitus [10.5 (1.8-24.9) ng/ml; 10.1 (4.2-29.8) ng/mg urinary creatinine]. On study completion, HbA(1c) fell from 11.6 +/- 2.0 to 5.4 +/- 0.6% (P < 0.001). Improved metabolic control was not associated with changes in plasma (9.4 (2.6-19.5)/5.9 (1.6-21.5)/7.0 (2.3-30.2)/10.5 (1.8-24.9) ng/ml at baseline, 1, 4 and 16 weeks, respectively) or urinary (12.0 (4.7-29.5)/10.9 (1.5-20.5)/8.7 (4.3-16.9)/10.1 (4.2-29.8) ng/mg urinary creatinine) TGF-beta1 levels. A statistically significant correlation was observed between plasma TGF-beta1 and insulin dosage (U/kg/day) (r = 0.52, P = 0.037).

CONCLUSIONS

The increased TGF-beta1 production observed herein was not modulated by glycaemic reduction and could be a response to immuno-inflammatory activation present at the onset of Type 1 diabetes.

Glycated hemoglobin level is strongly related to the prevalence of carotid artery plaques with high echogenicity in nondiabetic individuals: the Tromsø study

BACKGROUND

High levels of HbA1c have been associated with increased mortality and an increased risk of atherosclerosis assessed as carotid intima-media thickness or plaque prevalence. In the present population-based study, we examined the association between HbA1c and plaque prevalence with emphasis on plaque echogenicity in subjects not diagnosed with diabetes.

METHODS AND RESULTS

HbA1c measurements and ultrasonography of the carotid artery were performed in 5960 subjects (3026 women, 2934 men) 25 to 84 years of age. Plaque morphology was categorized into 4 groups from low echogenicity (soft plaque) to strong echogenicity (hard plaque). HbA1c was categorized into 5 groups: <5.0%, 5.0% to 5.4%, 5.5% to 5.9%, 6.0% to 6.4% and >6.4%. Carotid plaque prevalence increased with increasing HbA1c level (P for linear trend=0.002). The OR for hard plaques versus no plaques was 5.8 in the highest HbA1c group (>6.4%) compared with subjects in the lowest group (<5.0%) after adjustment for several possible confounders. The risk of predominantly hard plaques was also significantly associated with HbA1c levels, although the ORs at each level were somewhat lower than for hard plaques. With respect to the risk of soft plaques versus no plaques, no statistically significant relationship with HbA1c levels was found.

CONCLUSIONS

Metabolic changes reflected by HbA1c levels may contribute to the development of hard carotid artery plaques, even at modestly elevated levels.

Enhanced expression of transforming growth factor-beta isoforms in the neural tube of embryos derived from diabetic mice exposed to cyclophosphamide

We analyzed the expression pattern of transforming growth factor-beta isoforms (TGF-beta1, TGF-beta2 and TGF-beta3) in the developing brain of embryos derived from the normal and diabetic mice exposed to cyclophosphamide (CP), a cytotoxic teratogen. The CP-treated diabetic embryos showed significantly more TGF-beta1 and TGF-beta2 immunoreactive cells in the regions of telencephalon and diencephalon in comparison to that of CP-treated non-diabetic embryos. Moreover, no cells expressing TGF-beta isoforms were detectable in the developing brain of normal and diabetic embryos. The mRNA expression levels of TGF-beta isoforms were found to be significantly increased in the developing brain of CP-treated diabetic embryos compared to that of CP-treated non-diabetic embryos as measured by quantitative real time reverse transcription-polymerase chain reaction. The enhanced expression levels of TGF-beta isoforms appear to be associated with the increased frequency of neural tube defects observed in the diabetic embryos exposed to CP.

Glycated albumin increases oxidative stress, activates NF-kappa B and extracellular signal-regulated kinase (ERK), and stimulates ERK-dependent transforming growth factor-beta 1 production in macrophage RAW cells

Albumin modified by Amadori glucose adducts has been shown to modulate signal transduction and induce alterations in renal glomerular cells that contribute to the development of diabetic nephropathy. However, the participation of this nonenzymatically glycated protein in the pathobiology of atherosclerotic cardiovascular disease in diabetes has not been established. To probe this issue, we used macrophage RAW cells to assess the effects of glycated albumin on molecular events implicated in the pathogenesis of diabetes-related vascular complications. RAW cells were cultured in medium containing 5.5 mmol/L glucose and glycated or nonglycated albumin, with and without the addition of PD98059, a specific inhibitor of mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK), followed by analysis of phosphorylated ERK and the nuclear translocation of nuclear factor (NF)-kappa B and measurement of cellular content of thiobarbituric acid-reactive substances and the concentration of transforming growth factor (TGF)-beta(1) in the spent medium. We demonstrate, for the first time, that glycated albumin activates RAW cell ERK and promotes ERK-dependent increases in TGF-beta(1) production, oxidative stress, and NF-kappa B activation. Preincubation with the antioxidant alpha-lipoic acid partially prevented the glycated albumin-induced increase in NF-kappa B activation. These findings indicate that Amadori-modified glycated albumin modulates macrophage cell biology independent of high glucose concentration. The effects of glycated albumin on RAW cell molecular mediators and cytokine production may have pathophysiologic significance with respect to the accelerated atherosclerosis that occurs in diabetes.