Genetic variability in the RAGE gene: Possible implications for nutrigenetics, nutrigenomics, and understanding the susceptibility to diabetic complications

Complex chemical processes called nonenzymatic glycation and glycoxidation are one of the interesting examples of potentially harmful interaction between nutrition and disease. This review summarizes factors influencing the extent of glycoxidation in health and disease and especially focuses on the role of genetic variability in "glycoxidation-related genes" in a disease and diet-related pathogenesis. Possible interaction between genetic variability in relevant loci and dietary advanced glycation end products (AGEs) is considered. As AGEs possess a wide range of chemical and biological effects, the interindividual functional variability in systems dealing with glycoxidation could have a significant nutrigenomic and nutrigenetic consequences.

Preliminary evidence of genetic anticipation in type 2 diabetes mellitus

BACKGROUND

The term "anticipation" in genetic diseases refers to earlier age at onset and/or increased severity in successive generations. Several diseases with genetic anticipation include rheumatoid arthritis, Crohn's disease, Schizophrenia, Graves' disease and several other neuropsychiatric disorders. The aim of the present study was to investigate whether genetic anticipation may occur in diabetes.

MATERIAL/METHODS

The medical records of 485 subjects with type 2 diabetes, seen in the Diabetes Clinic were screened for subjects with a family history of diabetes and also aware of a definite date of diagnosis for both the subject and their family member. Ninety-six parent-child pairs with a known definite date of diagnosis of type 2 diabetes were identified and the age at onset of diabetes between two parent-child generations was compared.

RESULTS

The age at diagnosis of the subjects with positive family history of diabetes was lower than those with no family history of diabetes (48.82+/-12 vs. 56.18+/-13; p<0.001). There was a significant difference in the mean age at diagnosis between the 1(st) generation and 2(nd) generation (57.39 vs. 52.03 years p<0.0001). When the age at diagnosis of the subjects with siblings was compared (38 sibling pairs), there was no significant difference noted (52.21 vs. 50.57; p=0.35).

CONCLUSIONS

Patients in the second affected generation seem to acquire the disease at an earlier time in life, indicating strong evidence of anticipation. We conclude that genetic anticipation might occur in type 2 diabetes.

Myocardial Insulin Resistance and Cardiac Complications of Diabetes

Cardiovascular disease is a major cause of mortality and morbidity in individuals with obesity, type 2 diabetes and the metabolic syndrome. The mechanisms for this are partially understood, but include increased atherosclerosis, hypercoagulability and increased hypertension. Epidemiological data suggests however, that a component of the excess cardiovascular mortality occurs independently of underlying coronary artery disease. Indeed, diabetes is an independent risk factor for the development of heart failure and the mechanisms responsible remain to be clarified. Insulin resistance in skeletal muscle, adipose tissue and the liver are widely recognized features of obesity and type 2 diabetes, and contribute to the pathogenesis of impaired glucose homeostasis. Insulin resistance has also been described in the vasculature, and may contribute to endothelial dysfunction and atherosclerosis. The heart is an insulin responsive organ and less is known about whether or not the heart becomes insulin resistant in diabetes and what the pathogenic consequences of this might be. This review will discuss the currently available evidence from human and animal studies, that the heart may become insulin resistant in obesity and type 2 diabetes. The potential consequences of this on cardiac structure, function and metabolism will be discussed as well as recent data from transgenic mice with perturbed cardiac insulin sensitivity that have shed interesting new insight into potential mechanisms linking cardiac insulin resistance with myocardial dysfunction in diabetes.

Hypoadiponectinaemia and high risk of type 2 diabetes are associated with adiponectin-encoding (ACDC) gene promoter variants in morbid obesity: evidence for a role of ACDC in diabesity

AIMS/HYPOTHESIS

Morbid obesity (BMI>40 kg/m(2)) affecting 0.5-5% of the adult population worldwide is a major risk factor for type 2 diabetes. We aimed to elucidate the genetic bases of diabetes associated with obesity (diabesity), and to analyse the impact of corpulence on the effects of diabetes susceptibility genes.

METHODS

We genotyped known single nucleotide polymorphisms (SNPs) in the adiponectin-encoding adipocyte C1q and collagen-domain-containing (ACDC) gene (-11,391G>A, -11,377C>G, +45T>G and +276G>T), the peroxisome proliferator-activated receptor gamma (PPARG) Pro12Ala SNP and ACDC exon 3 variants in 703 French morbidly obese subjects (BMI 47.6+/-7.4 kg/m(2)), 808 non-obese subjects (BMI<30 kg/m(2)) and 493 obese subjects (30< or =BMI<40 kg/m(2)).

RESULTS

Two 5'-ACDC SNPs -11,391G>A, -11,377C>G were associated with adiponectin levels (p=0.0003, p=0.008) and defined a "low-level" haplotype associated with decreased adiponectin levels (p=0.0002) and insulin sensitivity (p=0.01) and with a risk of type 2 diabetes that was twice as high (p=0.002). In contrast, the prevalence of the PPARG Pro12Ala was identical in diabetic and normoglycaemic morbidly obese subjects. The PPARG Pro12 allele only displayed a trend of association with type 2 diabetes in the non-obese group. ACDC exon 3 variants were associated with type 2 diabetes in the non-obese group only (odds ratio 7.85, p<0.0001). In contrast, the 5'-ACDC "low-level" haplotype was associated with type 2 diabetes in obese and morbidly obese subjects (odds ratio 1.73 and 1.92) but not in non-obese individuals.

CONCLUSIONS/INTERPRETATION

These data clarify the contribution of the 5'-ACDC SNPs to the risk of diabesity. Their interaction with corpulence suggests for the first time a different genetic profile of type 2 diabetes in morbidly obese patients compared with in less obese individuals.

CTLA-4 +49 A/G polymorphism is associated with predisposition to type 1 diabetes in Iranians

CTLA-4 is a homeostatic regulator of T cell activation and is believed to play a critical role in peripheral tolerance. The contribution of CTLA-4 gene variants to type 1 diabetes has been analyzed in several ethnic groups. In this study, the association of CTLA-4 +49 A/G polymorphism with type 1 diabetes was investigated in Iranian patients. One hundred and nine patients and 331 healthy subjects formed the studied populations. CTLA-4 A/G polymorphism at position 49 in exon 1 was identified using PCR-SSCP and PCR-RFLP methods. Patient numbers with A/G, A/A and G/G genotypes were 78 (71.5%), 21 (19.3%) and 10 (9.2%) while in healthy controls, these were 149 (45%), 146 (44.2%) and 36 (10.8%), respectively. A significant decrease in the frequency of the A/A genotype was observed in the diabetes group (p = 0.000004). In diabetic subjects, the allele frequency of G was also higher than in controls (45% versus 33.4%, p = 0.00269). The differences in the genotypes and the alleles were greater in patients with younger age of diabetes onset (age < or = 15 years) compared with controls (p = 0.000001 and p = 0.000579, respectively). The distribution of the CTLA-4 polymorphism between patients did not show any significant difference according to diabetic ketoacidosis at onset. In conclusion, the result of this study in combination with the previous reports of other ethnic populations showed that CTLA-4 +49 A/G polymorphism confers genetic susceptibility to type 1 diabetes, particularly in younger individuals.

Differences in gene expression profiles of diabetic and nondiabetic patients undergoing cardiopulmonary bypass and cardioplegic arrest

BACKGROUND

Diabetes mellitus is an independent risk factor for early postoperative mortality and complications after coronary artery bypass grafting (CABG). We sought to compare the cardiac gene expression responses to cardiopulmonary bypass (CPB) and cardioplegic arrest (C) in patients with and without diabetes.

METHODS AND RESULTS

Twenty atrial myocardium samples were harvested from 5 type II insulin-dependent diabetic and 5 matched nondiabetic patients undergoing CABG, before and after CPB/C. Oligonucleotide microarray analyses of 12625 genes were performed on the 10 sample pairs using matched pre-CPB tissues as controls. Array results were validated with Northern blotting and immunoblotting. Compared with pre-CPB/C, post-CPB/C myocardial tissues revealed 851 upregulated and 480 downregulated genes with a threshold P< or =0.025 (signal-to-noise ratio, 4.04) in the diabetic group, compared with 480 upregulated and 626 downregulated genes (signal-to-noise ratio, 3.04) in the nondiabetic group (P<0.001). There were 18 genes that were upregulated >4-fold in diabetic and nondiabetic patients (including inflammatory/transcription activators FOS, CYR 61, and IL-6, apoptotic gene NR4A1, stress gene DUSP1, and glucose-transporter gene SLC2A3). However, 28 genes showed such marked upregulation in the diabetic group exclusively (including inflammatory/transcription activators MYC, IL8, IL-1beta, growth factor vascular endothelial growth factor, amphiregulin, and glucose metabolism-involved gene insulin receptor substrate 1), and 27 genes in the nondiabetic group only, including glycogen-binding subunit PPP1R3C.

CONCLUSIONS

Gene expression profile after CPB/C is quantitatively and qualitatively different in patients with diabetes. These results have important implications for the design of tailored myocardial protection and operative strategies for diabetic patients undergoing CPB/C.

Congenital or late-onset myopathy in patients with the T14709C mtDNA mutation

Three patients with different clinical phenotypes harbored the same point mutation at nucleotide 14709 (T14709C) in the tRNAGlu gene of mitochondrial DNA (mtDNA). The first patient was a 21-month-old child with severe congenital myopathy, respiratory distress and mild mental retardation. Muscle biopsy showed about 12% cytochrome c oxidase (COX)-negative ragged-red fibers (RRFs), and markedly decreased activities of mitochondrial respiratory chain complexes I, III and IV. The other two patients were 51- and 55-year-old siblings with slowly progressive myopathy and diabetes mellitus. Muscle biopsy showed focal COX-negative RRFs and decreased activities of complexes I, III and IV. In all three patients, the T14709C mutation was abundant in muscle but present at lower levels in accessible tissues. Previously described patients with the same mutation also showed congenital or late-onset myopathy. Diabetes is frequently associated with both phenotypes and is a clinical clue to the molecular diagnosis.

Diabetes and chronic nitrate therapy as co-determinants of somatic DNA damage in patients with coronary artery disease

Somatic DNA damage has been linked to coronary artery disease (CAD). However, whether genetic instability is linked to CAD per se or to concomitant potentially genotoxic metabolic and pharmacological factors remains still unclear. The aim of this study was to evaluate the determinants of somatic DNA damage in a large population of patients undergoing coronary angiography. A total of 278 in-hospital patients (215 men, age 61.8+/-0.7 years) were studied by using micronucleus assay (MN) in human lymphocytes, which is one of the most commonly used biomarker for somatic DNA damage. Significant CAD (>50% diameter stenosis) was present in 210 patients (179 men, age 62.3+/-0.7 years). Normal coronary arteries were observed in 68 patients (35 men, age 60.2+/-1.7 years). There were no significant differences between patients with and without CAD, but patients with multivessel disease had the highest MN levels (P=0.01). MN frequency was also found significantly higher in presence of type 2 diabetes (P<0.0001), dyslipidemia (P=0.048) and nitrate therapy (P=0.0002). A significant additive effect was also observed between diabetes and nitrate therapy (P=0.02). On multivariate logistic regression analysis, diabetes [odds ratio=6.8 (95% confidence interval, 3.2-14.5), P<0.0001] and nitrate therapy [odds ratio=2.4 (95% confidence interval, 1.3-4.7), P=0.01] remained the only significant determinants for the 50th percentile of MN (>12 per thousand). These results indicated that diabetes and, to a lesser extent, chronic nitrate therapy are major determinants of somatic DNA instability in patients with CAD. DNA damage might represent an additional pathogenetic dimension and a possible therapeutic target in the still challenging management of coronary artery disease concerning diabetics.

Combined analysis of biochemical parameters in serum and differential gene expression in circulating leukocytes may serve as an ex vivo monitoring system to estimate risk factors for complications in Diabetes mellitus

OBJECTIVE

Oxidative stress plays a crucial role in the development of complications in Diabetes mellitus (DM). Individual sensitivity against stress, however, varies among DM-patients and results, therefore, in differential severity of consequent complications. To allow more complex interpretation of a delicate antioxidant/free radicals balance and its effect on cellular functions in individual DM-patients, we analysed a correlation between total antioxidant status (TAS), antioxidant gap (AtxGap), level of free radicals (FR), routine clinical biochemical parameters in blood and differential gene expression in circulating leukocytes of DM-patients versus non-diabetic individuals.

RESULTS AND CONCLUSIONS

Positive correlation was found between TAS and creatinine (p=0.05), AtxGap and iron (p=0.025), and between AtxGap and anti-streptolysin O (p=0.025). Whereas no correlation was found between FR and any of the routine clinical parameters tested, a negative correlation was observed between AtxGap and glucose content (p=0.025) and between AtxGap and gamma-glutamyltransferase (p=0.05). An increased content of FR was shown to influence significantly an expression of selected stress responsible genes in leukocytes. Transcription levels of NF-kappaB, XRCC1 and 90-kDa heat-shock protein A were increased in all DM-patients compared to non-diabetic individuals. In contrast, an expression of XIAP and cytochrome P450 reductase was up-regulated in patients with decreased levels of both FR and TAS and increased body mass index. This differential expression of the stress responsible genes might be further considered as a potential risk factor for diverse DM-complications helping also in reliable monitoring of supplemental antioxidant therapy and more complex interpretation of delicate antioxidant/free radicals balance.

Activation of the hexosamine pathway causes oxidative stress and abnormal embryo gene expression: involvement in diabetic teratogenesis

BACKGROUND

Oxidative stress is critical to the teratogenic effects of diabetic pregnancy, yet the specific biochemical pathways responsible for oxidative stress have not been fully elucidated. The hexosamine pathway is activated in many tissues during diabetes and could contribute to oxidative stress by inhibiting the pentose shunt pathway, thereby diminishing production of the cellular antioxidant, reduced glutathione (GSH).

METHODS

To test the hypothesis that activation of the hexosamine pathway might contribute to the teratogenic effects of diabetic pregnancy, pregnant mice were injected with glucose, to induce hyperglycemia, or glucosamine, to directly activate the hexosamine pathway. Embryo tissue fragments were also cultured in physiological glucose, high glucose, or physiological glucose plus glucosamine, to test effects on oxidative stress and embryo gene expression.

RESULTS

Glucosamine increased hexosamine synthesis and inhibited pentose shunt activity. There was a trend for transient hyperglycemia to have the same effects, but they did not reach statistical significance. However, both glucose and glucosamine significantly decreased GSH, and increased oxidative stress, as indicated by 2',7'-dichloro-dihydrofluorescein fluorescence. Glucose and glucosamine inhibited expression of Pax-3, a gene required for neural tube closure both in vivo and in vitro, and increased neural tube defects (NTDs) in vivo; these effects were prevented by GSH ethyl ester. High glucose and glucosamine inhibited Pax-3 expression by embryo culture, but culture in glutamine-free media to block the hexosamine pathway prevented the inhibition of Pax-3 expression by high glucose.

CONCLUSIONS

Activation of the hexosamine pathway causes oxidative stress through depletion of GSH and consequent disruption of embryo gene expression. Activation of this pathway may contribute to diabetic teratogenesis.

Structural, metabolic and endocrine analysis of the diabetes (db/db) hypogonadal syndrome: relationship to hypophyseal hypercytolipidemia

Expression of the diabetes (db/db) mutation in C57BL/KsJ mice results in functional suppression of the female pituitary-gonadal axis accompanied by premature utero-ovarian cytolipoatrophy. Cellular gluco- and lipo-metabolic disturbances promoted by the db/db systemic hyperglycemic-hyperinsulinemic state suppress pituitary gonadotropin release in response to gonadotropin-releasing hormone and gonadal steroid stimulation and results in a hypogonadal-infertility syndrome. Adult female C57BL/KsJ control (+/+ and +/? genotypes) and db/db littermates were monitored for associations in systemic and cellular alterations in luteinizing hormone (LH), follicle-stimulating hormone (FSH), gonadal steroid (binding) levels, and pituitary glucometabolic indices associated with db/db-enhanced lipid imbibition and cytostructural disruption. Obesity, hyperglycemia, and hyperinsulinemia characterized all db/db mutants relative to controls. Serum and pituitary progesterone and estradiol concentrations were suppressed in db/db mutants, in association with serum LH and FSH levels, but not with pituitary LH and FSH concentrations, which were comparable between groups. Pituitary insulin receptor binding and glucose utilization rates were suppressed in db/db groups relative to +/? indices. Structural and cytochemical analysis of anterior (AP), intermediate (IL), and neuro-(NP) hypophyseal lobes demonstrated prominent hypercytolipidemia in db/db mutants relative to controls. Prominent cytolipidemia was localized within well-granulated basophilic gonadotrophs and within IL and NP pituicytes. Vasolipidemia and interstitial cytoadiposity were prominent throughout all db/db pituitary lobes. Thus, disturbances associated with pituitary hypercytolipidemia are functional components of the expressed diabetes-associated hypogonadal syndrome in db/db mutants. Progressive alterations in hypophyseal cytoarchitecture are correlated with suppression of pituitary metabolic and endocrine indices, alterations that contribute to functional disruption of the pituitary-hypogonadal axis in C57BL/KsJ-db/db mice.

The M16 mouse: an outbred animal model of early onset polygenic obesity and diabesity

OBJECTIVE

To characterize the phenotypic consequences of long-term selective breeding for rapid weight gain, with an emphasis on obesity and obesity-induced diabetes (diabesity).

RESEARCH METHODS AND PROCEDURES

M16 is the result of long-term selection for 3- to 6-week weight gain from an ICR base population. Experiment 1 characterized males from both lines for body weights (3, 6, and 8 weeks), feed (4 to 8 weeks) and H(2)O (6 to 8 weeks) consumption, and heat loss, body composition, and levels of several plasma proteins at 8 weeks of age. Experiment 2 characterized differences between lines for both sexes at three ages (6, 8, and 16 weeks) and fed two diets (high and normal fat). Body weight, composition, blood glucose, and plasma insulin and leptin levels were evaluated after an 8-hour fast.

RESULTS

At all ages measured, M16 mice were heavier, fatter, hyperphagic, hyperinsulinemic, and hyperleptinemic relative to ICR. M16 males and females were hyperglycemic relative to ICR, with 56% and 22% higher fasted blood glucose levels at 8 weeks of age.

DISCUSSION

M16 mice represent an outbred animal model to facilitate gene discovery and pathway regulation controlling early onset polygenic obesity and type 2 diabetic phenotypes. Phenotypes prevalent in the M16 model, with obesity and diabesity exhibited at a young age, closely mirror current trends in human populations.

Deficiency of subsarcolemmal mitochondria in obesity and type 2 diabetes

The current study addresses a novel hypothesis of subcellular distribution of mitochondrial dysfunction in skeletal muscle in type 2 diabetes. Vastus lateralis muscle was obtained by percutaneous biopsy from 11 volunteers with type 2 diabetes; 12 age-, sex-, and weight-matched obese sedentary nondiabetic volunteers; and 8 lean volunteers. Subsarcolemmal and intermyofibrillar mitochondrial fractions were isolated by differential centrifugation and digestion techniques. Overall electron transport chain activity was similar in type 2 diabetic and obese subjects, but subsarcolemmal mitochondria electron transport chain activity was reduced in type 2 diabetic subjects (0.017 +/- 0.003 vs. 0.034 +/- 0.007 units/mU creatine kinase [CK], P = 0.01) and sevenfold reduced compared with lean subjects (P < 0.01). Electron transport chain activity in intermyofibrillar mitochondria was similar in type 2 diabetic and obese subjects, though reduced compared with lean subjects. A reduction in subsarcolemmal mitochondria was confirmed by transmission electron microscopy. Although mtDNA was lower in type 2 diabetic and obese subjects, the decrement in electron transport chain activity was proportionately greater, indicating functional impairment. Because of the potential importance of subsarcolemmal mitochondria for signal transduction and substrate transport, this deficit may contribute to the pathogenesis of muscle insulin resistance in type 2 diabetes.

Role of the interleukin-6 -174 G>C gene polymorphism in retinal artery occlusion

BACKGROUND AND PURPOSE

Proinflammatory cytokines including interleukin-6 (IL-6) are supposed to play a pivotal role in the development of atherosclerosis. A common polymorphism in the promoter of the IL-6 gene (IL-6 -174G>C) affects plasma IL-6 concentrations and has been suggested as a risk factor for cardiovascular disease. The aim of the present case-control study was to investigate the role of this polymorphism for retinal artery occlusion (RAO).

METHODS

One hundred eighty-two patients with RAO and 307 control subjects were genotyped for the IL-6 -174G>C polymorphism. Genotypes were determined by fluorogenic exonuclease (TaqMan) assay.

RESULTS

The prevalence of the CC genotype was significantly lower in patients with RAO than in control subjects (10.4% versus 19.9%; P=0.006). Homozygosity for the C allele was associated with an odds ratio of 0.50 (95% CI, 0.28 to 0.89) for RAO.

CONCLUSIONS

The CC genotype of the IL-6 -174G>C polymorphism may be associated with a protective effect against RAO.

Molecular basis of Kir6.2 mutations associated with neonatal diabetes or neonatal diabetes plus neurological features

Inwardly rectifying potassium channels (Kir channels) control cell membrane K(+) fluxes and electrical signaling in diverse cell types. Heterozygous mutations in the human Kir6.2 gene (KCNJ11), the pore-forming subunit of the ATP-sensitive (K(ATP)) channel, cause permanent neonatal diabetes mellitus (PNDM). For some mutations, PNDM is accompanied by marked developmental delay, muscle weakness, and epilepsy (severe disease). To determine the molecular basis of these different phenotypes, we expressed wild-type or mutant (R201C, Q52R, or V59G) Kir6.2/sulfonylurea receptor 1 channels in Xenopus oocytes. All mutations increased resting whole-cell K(ATP) currents by reducing channel inhibition by ATP, but, in the simulated heterozygous state, mutations causing PNDM alone (R201C) produced smaller K(ATP) currents and less change in ATP sensitivity than mutations associated with severe disease (Q52R and V59G). This finding suggests that increased K(ATP) currents hyperpolarize pancreatic beta cells and impair insulin secretion, whereas larger K(ATP) currents are required to influence extrapancreatic cell function. We found that mutations causing PNDM alone impair ATP sensitivity directly (at the binding site), whereas those associated with severe disease act indirectly by biasing the channel conformation toward the open state. The effect of the mutation on ATP sensitivity in the heterozygous state reflects the different contributions of a single subunit in the Kir6.2 tetramer to ATP inhibition and to the energy of the open state. Our results also show that mutations in the slide helix of Kir6.2 (V59G) influence the channel kinetics, providing evidence that this domain is involved in Kir channel gating, and suggest that the efficacy of sulfonylurea therapy in PNDM may vary with genotype.

Maldi-TOF analysis of portal sera of pancreatic cancer patients: identification of diabetogenic and antidiabetogenic peptides

BACKGROUND

Pancreatic cancer (PC) associated diabetes mellitus (DM) might be consequent to the diabetogenic effects of tumour products, possibly acting via nitric oxide (NO). Our aims were: (1) to verify whether PC associated DM determines an increased hepatic NO and (2) using MALDI-TOF analysis, to evaluate the peptide composition of PC cell conditioned media (CM) and of portal sera from patients with PC with (n=7) or without (n=4) DM.

METHODS

In liver tissue homogenates of 23 patients with PC (n=17) or chronic pancreatitis (n=6) GAPDH mRNA and activity, glucose, lactate, nitrite and nitrate were assayed. MALDI-TOF analysis was performed in three PC cell lines CM, and in portal sera from patients with PC.

RESULTS

Higher GAPDH mRNA and nitrite were found in patients with than in patients without DM. In PC cell CM, only 9 among a total of 75 fragments identified, were tumour specific. One hundred seventy-three fragments were identified in the portal sera of patients: one was positively and six fragments were negatively correlated with DM.

CONCLUSIONS

Unlike liver GAPDH, NO appears to be involved in PC associated DM. In portal sera, the absence, rather than the presence, of specific fragments, appears to be correlated with the development of DM.

Association of APOE genotype with carotid atherosclerosis in men and women

The aim of this study was to determine the association between APOE genotype and carotid atherosclerosis, defined as intimal-medial thickness (IMT) and stenosis, and to assess if other cardiovascular risk factors modify this association. A total of 1,315 men and 1,408 women from the Framingham Offspring Study underwent carotid ultrasound during examination cycle 6 and had complete data on APOE genotype. Three APOE genotype groups were defined: APOE2 (including E2/E2, E3/E2 genotypes), APOE3 (E3/E3), and APOE4 (including E4/E3, E4/E4 genotypes). Carotid IMT and the presence of carotid stenosis > 25% were determined by ultrasonography. In women, the APOE2 group was associated with lower carotid IMT (0.67 vs. 0.73 mm) and lower prevalence of stenosis (odds ratio = 0.49; 95% confidence interval = 0.30-0.81) compared with the APOE3 group. In men, APOE genotype was not associated with carotid IMT or stenosis in the whole group; however, diabetes modified the association between APOE genotype and carotid IMT (P for interaction = 0.044). Among men with diabetes, the APOE4 group was associated with a higher internal carotid artery IMT (1.22 mm) than the APOE3 group (0.90 mm) or the APOE2 group (0.84 mm). The E2 allele was associated with lower carotid atherosclerosis in women, and the E4 allele was associated with higher internal carotid IMT in diabetic men.

Estrogenic stimulation of ovarian follicular maturation in diabetes (db/db) mutant mice: restoration of euglycemia prevents hyperlipidemic cytoatrophy

The diabetes (db/db) mutation (leptin-receptor defect) induces a hyperglycemic-hyperinsulinemic endometabolic environment that promotes hypercytolipidemic ovarian involution in C57BL/KsJ mice, resulting in reproductive sterility and eventual organoatrophy. The effectiveness of low-dose (1.0 microg/sc/3.5 day intervals), 17- beta-estradiol therapy (E2-HRx), initiated prior to expression of the overt diabetes-obesity syndrome (DOS), on preventing female ovarian follicular cytolipid atrophy was evaluated by analysis of cytochemical, endocrine, and tissue lipo-metabolic indices relative to oil-vehicle treated control (+/?) and (db/db) groups. Chronic low-dose E2-HRx moderated DOS-induced trends in (db/db) groups, maintaining lowered body weights, and systemic euglycemia while stimulating ovarian weight indices. E2-HRx prevented the dramatic hypercytolipidemic condition associated with ovarian follicular involution in (db/db) mice, as evidenced by progressive viable follicular maturation, cytomorphometric analysis of tertiary follicular development, and pre-luteinization indices with diminished follicular atresia rates. The coincident stimulation of tissue lipoprotein lipase and acetyl CoA carboxylase activities in (db/db) ovarian compartments, under persistent hyperinsulinemic influences, indicated that E2-HRx effectively moderated both the structural and hyperlipometabolic consequences of DOS from promoting (db/db)-associated reproductive organoatrophy. Thus, the patho-reproductive alterations induced by the (db/db) mutation can be moderated through low-dose steroidal therapy, the efficacy of which is suspected to occur by steroid-specific nuclear transcription or post-insulin receptor modulation of gluco-metabolic cascades in reproductive target cells.

A novel aminosterol reverses diabetes and fatty liver disease in obese mice

BACKGROUND/AIMS

Non-alcoholic fatty liver disease (NAFLD) is common in obesity. However, weight reduction alone does not prevent the development or progression of NAFLD. Since NAFLD is associated with insulin resistance and diabetes, we hypothesized that improvement of these factors would reverse obesity-related NAFLD.

METHODS

We examined the effects of an aminosterol, 1436, on glucose, lipids and liver metabolism in Lep(ob/ob) mice, a model of obesity, severe insulin resistance, diabetes, hyperlipidemia and hepatic steatosis.

RESULTS

1436 decreased body weight, specifically fat content, by inhibiting food intake and increasing energy expenditure. In contrast to weight loss from food restriction, this aminosterol specifically lowered circulating lipids, reversed hepatic steatosis and normalized alanine aminotransferase level. 1436 decreased glucose, increased adiponectin and enhanced insulin action in liver. These changes culminated in inhibition of hepatic triglyceride synthesis and increased fatty acid oxidation. Gene expression studies confirmed a reduction in lipogenic enzymes in liver, and elevation of enzymes involved in lipid catabolism.

CONCLUSIONS

These results demonstrate that 1436 is an effective treatment for insulin resistance and hepatic steatosis in Lep(ob/ob) mice, by decreasing hepatic lipid synthesis and stimulating lipolysis. In contrast, weight loss from food restriction has no substantial effect on insulin resistance, lipids and hepatic steatosis.

Variable onset determinants and consequences of diabetes (db/db) obesity mutation expression: adrenergic promotion of utero-ovarian dysfunction

Expression of the diabetes ( db/db) genotype mutation in female C57BL/KsJ mice induces a complex diabetes-obesity syndrome (DOS) responsible for reproductive tract involution promoted by hypercytolipidemia (HCL). Current studies define the complex and influences of the endometabolic variables that promote reproductive tract involution at the time of initial db/db mutation expression onset in female C57BL/KsJ mice. Littermate-paired, normal ( +/?) and db/db groups were isolated between 2 - 4 weeks of age and tissue samples analyzed for utero-ovarian alterations induced by the systemic, tissue, cellular and structural consequences of mutation expression. Significantly elevated body weights, blood glucose concentrations and serum insulin levels contrasted with atrophic utero-ovarian indices in db/db mutants compared to +/? groups. The onset of the db/db-expression promoted obesity and a mild hyperglycemic-hyperinsulinemic state. Initial db/db expression was characterized by significantly increased utero-ovarian insulin binding without variation in membrane insulin receptor concentrations. However, significant elevations in tissue glucose sequestration rates, norepinephrine (NE) concentrations and triacylglyceride lipase activity in db/db groups indicated that a complex of endometabolic counter-regulatory influences promoted the metabolic shunting of excess glucose and triglyceride moieties towards hypercytolipidemic storage. The resulting DOS-promoted accumulation of utero-ovarian cytolipidemic pools compromised reproductive tract cytoarchitecture in db/db mice. The results of these studies indicate that the inability of utero-ovarian tissue compartments to exhibit metabolic adaptation to the enhanced availability, transport and cellular imbibition of extracellular glucose-lipid pools promotes the initial cellular compromise recognized to induce reproductive failure in db/db mutants.

Hypophyseal lipoapoptosis: diabetes (db/db) mutation-associated cytolipidemia promotes pituitary cellular disruption and dysfunction

Expression of the diabetes (db/db) mutation in C57BL/KsJ mice suppresses the female pituitary-gonadal axis via progressive cytolipidemic disruption of hypophyseal gonadotropin release, culminating in premature involution of the reproductive tract and manifest infertility. The current studies define the systemic, endocrine, cytochemical and structural apoptotic changes that result from pituitary hypercytolipidemia induced by db/db mutation expression in this Type II diabetes-obesity syndrome (DOS) model. Adult female C57BL/KsJ control (+/? genotype) and db/db littermates were monitored for systemic and cellular alterations in LH-, FSH- and gonadal steroid-secretion, and coincident pituitary apoptosis, as indexed by TUNEL labeled 3' nuclear DNA-fragmentation, associated with cytolipid depositions. Obesity, hyperglycemia and hyperinsulinemia characterized all db/db-mutants relative to +/? groups. Serum progesterone (P) and estradiol (E2) concentrations were suppressed in db/db mutants coincident with decreased plasma LH and FSH concentrations relative to +/? values. Cytochemical analysis of anterior (AP) pituitary cell subtypes indicated that db/db mutants demonstrated prominent hypercytolipidemia relative to +/? pituitary cytoarchitecture. Cytolipidemic vacuoles were localized within protein vesiculated db/db hypophyseal basophilic and acidophilic cell populations. Hypophyseal cytoadiposity in db/db AP cells was co-localized with prominent cellular apoptotic TUNEL labeling of nuclear 3'-DNA fragments in cells demonstrating vesicular depopulation and cytolytic vacuolization. These data represent the first demonstration of co-localized hypercytolipidemic and cytoapoptotic disruptive events occurring concurrently in a hypopituitary-hypogonadal syndrome model following expression of the Type II (NIDDM) diabetes-obesity syndrome in db/db-mutants. The coincident and progressive vascular-, interstitial- and cyto-lipidemic alterations in hypophyseal cytoarchitecture correlated with the concurrent apoptotic disruption of pituitary endocrine cytoarchitecture and supressed gonadal steroid synthesis, influences which collectively contribute to the premature involution of the pituitary-gonadal axis in C57BL/KsJ- db/db mice.

The BBZDR/Wor Rat Model for Investigating the Complications of Type 2 Diabetes Mellitus

Congenic and inbred strains of rats offer researchers invaluable insight into the etiopathogenesis of diabetes and associated complications. The inbred Bio-Breeding Zucker diabetic rat (BBZDR)/Wor rat strain is a relatively new and emerging model of type 2 diabetes. This strain was created by classical breeding methods used to introgress the defective leptin receptor gene (Lepr(fa)) from insulin-resistant Zucker fatty rats into the inbred BBDR/Wor strain background. The diabetic male BBZDR/Wor rat is homozygous for the fatty mutation and shares the genetic background of the original BB strain. Although lean littermates are phenotypically normal, obese juvenile BBZDR/Wor rats are hyperlipidemic and hyperleptinemic, become insulin resistant, and ultimately develop hyperglycemia. Furthermore, the BBZDR/Wor rat is immune competent and does not develop autoimmunity. Similar to patients with clinical diabetes, the BBZDR/Wor rat develops complications associated with hyperglycemia. The BBZDR/Wor rat is a model system that fully encompasses the ability to study the complications that affect human type 2 diabetic patients. In this review, recent work that has evaluated type 2 diabetic complications in BBZDR/Wor rats is discussed, including the authors' preliminary unpublished studies on cardiovascular disease.