Erythrocyte Integrity, Thymocyte Volume Regulation, and Functional State of the Heart during Ischemia/Reperfusion in Rats with Type 2 Diabetes Mellitus.

Rewarming from accidental hypothermia is associated with fatal circulatory derangements. To investigate potential pathophysiological mechanisms involved, we examined heart function and metabolism in a rat model rewarmed after 4 h at 15-13 degrees C. Hypothermia resulted in a significant reduction of left ventricular (LV) systolic pressure, cardiac output, and heart rate, whereas stroke volume increased. The maximum rate of LV pressure rise decreased to 191 +/- 28 mmHg/s from a control value of 9,060 +/- 500 mmHg/s. Myocardial tissue content of ATP, ADP, and glycogen was significantly reduced, whereas lactate content remained unchanged. After rewarming, heart rate returned to control value, whereas LV systolic pressure, cardiac output, and stroke volume all remained significantly depressed. The posthypothermic maximum rate of LV pressure rise was 5,966 +/- 1.643 mmHg/s. The posthypothermic myocardial lactate content was significantly increased (to 13.3 +/- 3.2 nmol/mg from control value of 5.7 +/- 1.9 nmol/mg), and ATP and glycogen remained significantly lowered. Creatine phosphate or energy charge did not change significantly during the experiment. The finding of deteriorated myocardial mechanical function and a shift in energy metabolism shows that the heart could be an important target during hypothermia and rewarming in vivo, thus contributing to the development of a posthypothermic circulatory collapse.

ObjectiveThe endogenous gaseous transmitter hydrogen sulfide (H2S) is an important regulator of the cardiovascular system and is reported to have cardioprotective activity against ischemia/reperfusion (I/R) injury. We investigated the cardioprotective effect of H2S added in cardioplegia against I/R injury in global cardioplegic arrest.MethodsIsolated Wistar rat hearts were perfused in Langendorff apparatus and underwent 30 min perfusion, 120 min cold ischemia, and 90 min reperfusion. The rats were randomly divided into 5 groups: Control group, ischemic and reperfusion (I/R), St. Thomas cardioplegia (St. Thomas +I/R), St. Thomas plus H2S donor NaHS (NaHS+St.Thomas+I/R), St.Thomas plus NaHS and glibenclamide (an antagonist of KATP channel; NaHS+Glib+St.Thomas+I/R). The following indices were compared among the groups: the change of left ventricular systolic pressure (LVSP), left ventricular end diastolic pressure (LVEDP), heart rate, heart rhythm, and coronary blood flow. The difference in left ventricular developed pressure (LVDP), the maximum left ventricular pressure rise rate (+dp/dtmax), and the maximum left ventricular pressure drop rate (‐dp/dtmax) were also compared. Western blot was used to detect the changes of related myocardial enzymes among different groups.ResultsNaHS+St.Thomas+I/R treatment significantly improved cardiac function (LVSP, LVDP, +dp/dtmax and ‐dp/dtmax) compared to other groups (p<0.05), although no significant differences on coronary flow and heart rate were observed. After reperfusion, the frequency of ventricular arrhythmia in I/R group and St.Thomas+I/R group was significantly higher than that in NaHS+St.Thomas+I/R group. Further, the expression of cardiac Troponin T, troponin I, and creatine kinase in the NaHS+St.Thomas+I/R group was significantly lower than that in other groups (p<0.05).ConclusionCardioplegia containing H2S confers significant protection against global I/R injury during cold cardioplegic arrest. This effect is associated with opening of the myocardial KATP channels. Therefore, H2S may be a useful adjunct to cardioplegic solutions in heart surgery.

The studies on the risk of tuberculosis (TB) in patients with type 1 diabetes mellitus (T1DM) alone are limited. We examined this relationship using a population-based retrospective cohort study. From claims data of the National Health Insurance system of Taiwan, we identified 5195 patients with T1DM newly diagnosed from 2002 to 2011 and 20,780 randomly selected controls without T1DM, frequency matched by age, sex, and year of diagnosis. Both cohorts were followed up until the end of 2011 to evaluate the risk of TB. The overall incidence of TB was 4.07-fold higher in the T1DM cohort than in the control cohort (1.18 vs 0.29 per 1000 person-years, P < 0.001). Compared with the controls, the Cox model estimated adjusted hazard ratios (HRs) of TB in patients with T1DM were greater in men than in women (4.62 vs 3.59) and in adults than in children (4.06 vs 3.37), but not significant. The adjusted HR was much greater for those with comorbidities than those without comorbidities (14.6 vs 1.62, P < 0.001). Compared with the controls, the patients with T1DM were also more likely to develop TB with multiple emergency room visits (adjusted HR: 116.1, 95% confidence interval [CI] = 43.8–307.4) or hospitalizations (adjusted HR: 86.5, 95% CI = 33.7–222.4). Patients with T1DM are at elevated risks of developing TB with much higher HRs for those with comorbidities, within the first year of diagnosis, and with frequent emergency cares or hospitalizations.

Alterations in left ventricular (LV) contractility, relaxation, and chamber dimensions induced by efferent sympathetic nerve stimulation were investigated in nine anesthetized open-chest dogs in sinus rhythm. Supramaximal stimulation of acutely decentralized left stellate ganglia augmented heart rate, LV systolic pressure, and rate of LV pressure rise (maximum +dP/dt, 1,809 +/- 191 to 6,304 +/- 725 mmHg/s) and fall (maximum -dP/dt, -2,392 +/- 230 to -4,458 +/- 482 mmHg/s). It also reduced the time constant of isovolumic relaxation, tau (36.5 +/- 4.8 to 14.9 +/- 1.1 ms). Simultaneous two-dimensional echocardiography recorded reductions in end-diastolic and end-systolic LV cross-sectional chamber areas (23 and 31%, respectively), an increase in area ejection fraction (32%), and increases in end-diastolic and end-systolic wall thicknesses (14 and 13%, respectively). End-systolic and end-diastolic wall stresses were unchanged by stellate ganglion stimulation (98 +/- 12 to 95 +/- 9 dyn x 10(3)/cm2; 6.4 +/- 2.4 to 2.4 +/- 0.3 dyn x 10(3)/cm2, respectively). Atrial pacing to similar heart rates did not alter monitored indexes of contractility. Dobutamine and isoproterenol induced changes similar to those resulting from sympathetic neuronal stimulation. These data indicate that when the efferent sympathetic nervous system increases left ventricular contractility and relaxation, concomitant reductions in systolic and diastolic dimensions of that chamber occur that are associated with increasing wall thickness such that LV wall stress changes are minimized.

BackgroundDiabetic cardiomyopathy (DCM) is a disorder of the heart muscle in people with diabetes, which is characterized by both systolic and diastolic dysfunction. The effective treatment strategy for DCM has not been developed.MethodsRats were divided into 3 groups with different treatment. The control group was only injected with citrate buffer (n = 8). The diabetes group and diabetes treated group were injected with streptozotocin to induce diabetes. After success of diabetes induction, the rats with diabetes were treated with (diabetes treated group, n = 8) or without (diabetes group, n = 8) recombinant human Neuregulin-1 (rhNRG-1). All studies were carried out 16 weeks after induction of diabetes. Cardiac catheterization was performed to evaluate the cardiac function. Apoptotic cells were determined by TUNEL staining. Left ventricular (LV) sections were stained with Masson to investigate myocardial collagen contents. Related gene expressions were analyzed by quantitative real-time PCR (qRT-PCR).ResultsDiabetes impaired cardiac function manifested by reduced LV systolic pressure (LVSP), maximum rate of LV pressure rise and fall (+dp/dt max and -dp/dt max) and increased LV end-diastolic pressure (LVEDP). The rhNRG-1 treatment could significantly alleviate these symptoms and improve heart function. More TUNEL staining positive cells were observed in the diabetic group than that in the control group, and the rhNRG-1 treatment decreased apoptotic cells number. Furthermore, qRT-PCR assay demonstrated that rhNRG-1 treatment could decrease the expression of bax and caspase-3 and increase that of bcl-2. Collagen volume fraction was higher in the diabetic group than in the control group. Fibrotic and fibrotic related mRNA (type I and type III collagen) levels in the myocardium were significantly reduced by administration of rhNRG-1.ConclusionrhNRG-1 could significantly improve the heart function and reverse the cardiac remodeling of DCM rats with chronic heart failure. These results support the clinical possibility of applying rhNRG-1 as an optional therapeutic strategy for DCM treatment in the future.

Red blood cells (RBCs) from patients with type 2 diabetes mellitus (T2DM) induce endothelial dysfunction and impair cardiac function following ischemia via increase in RBC arginase and oxidative stress. Here, we aimed to elucidate whether the effect of RBC-mediated cardiac impairment following ischemia and endothelial dysfunction in T2DM is dependent on glycemic control. Patients with T2DM at poor glycemic control (T2DM PGC) and at improvement in glycemic control (T2DM IGC) and healthy subjects were recruited. Isolated RBCs from subjects were incubated with aortic rings from healthy wild-type rats with subsequent evaluation of endothelium-dependent relaxation (EDR) using wire myograph. Moreover, RBCs were administered to isolated wild-type rat hearts with subsequent evaluation of left ventricular developed pressure (LVDP) during reperfusion using Langendorff setup. In separate experiments, RBCs were preincubated with an arginase inhibitor before perfusion. Blood glucose and glycated hemoglobin were 33 and 26%, respectively, lower in T2DM IGC compared with those in T2DM PGC. RBCs from T2DM PGC and T2DM IGC impaired EDR to a similar magnitude compared with RBCs from healthy subjects. LVDP was significantly impaired in hearts given RBCs from T2DM PGC as compared with those from healthy subjects. The impairment of LVDP induced by T2DM PGC was attenuated by RBCs from T2DM IGC. Arginase inhibition improved LVDP to a similar extent between T2DM PGC and IGC groups. These observations indicate that glycemic control abrogate the impairment in postischemic recovery but not endothelial dysfunction induced by RBCs from T2DM. Moreover, inhibition of RBC arginase improves cardiac function irrespective of glycemic control.

Left ventricular pressure (LVP) fall is a manifestation of relaxation and is therefore regulated by non-uniformity and load, besides regulation by muscle inactivation. Non-uniformity and load are important and independent regulators of LVP fall. Non-uniformity induces a premature onset and decreased rate of LVP fall. With regard to load, the effects of preload, systolic LVP levels and systolic LVP waveform are distinct. In order to assess underlying muscle inactivation with indexes of LVP fall, it is critical to control non-uniformity and various aspects of load. This control should be inherent in experiments designed to evaluate interventions. If careful control of non-uniformity and load cannot be achieved, at least the effects of non-uniformity and load on timing and rate of LVP falls should be appreciated. Isovolumetric left ventricular pressure fall is a complex event including a rapid early and slower late phase. As a consequence, LVP fall cannot be described by a single index. Peak--dP/dt is measured at the transition between early and late LVP fall. Its value can be affected by changes of both phases. Interpretation of peak-dP/dt should therefore be cautious. LVP fall at and after mitral valve opening might be regulated differently from late LVP fall, as evaluated by the time constant tau. Loading effects of LVP fall after mitral valve opening can therefore not always be predicted from changes in tau. Load dependence is a concept based on experimental observations in isolated cardiac muscle, which describes the separation in time between shorter isotonic and longer isometric twitches. Temporal separation is illustrated by the response of cardiac muscle to late systolic load.(ABSTRACT TRUNCATED AT 250 WORDS)

To clarify the expression of N6-methyladenosine (m6 A) modulators involved in the pathogenesis of type 2 diabetes mellitus (T2DM). We further explored the association of serum insulin-like growth factor 2 mRNA-binding proteins 3 (IGF2BP3) levels and odds of T2DM in a high-risk population. The gene expression data set GSE25724 was obtained from the Gene Expression Omnibus, and a cluster heatmap was generated by using the R package ComplexHeatmap. Differential expression analysis for 13 m6 A RNA methylation regulators between nondiabetic controls and T2DM subjects was performed using an unpaired t test. A cross-sectional design, including 393 subjects (131 patients with newly diagnosed T2DM, 131 age- and sex-matched subjects with prediabetes, and 131 healthy controls), was carried out. The associations between serum IGF2BP3 concentrations and T2DM were modeled by restricted cubic spline and logistic regression models. Two upregulated (IGF2BP2 and IGF2BP3) and 5 downregulated (methyltransferase-like 3 [METTL3], alkylation repair homolog protein 1 [ALKBH1], YTH domain family 2 [YTHDF2], YTHDF3, and heterogeneous nuclear ribonucleoprotein [HNRNPC]) m6 A-related genes were found in islet samples of T2DM patients. A U-shaped association existed between serum IGF2BP3 levels and odds of T2DM according to cubic natural spline analysis models, after adjustment for body mass index, waist circumference, diastolic blood pressure, total cholesterol, and triglyeride. Multivariate logistic regression showed that progressively higher odds of T2DM were observed when serum IGF2BP3 levels were below 0.62 ng/mL (odds ratio 3.03 [95% confidence interval 1.23-7.47]) in model 4. Seven significantly altered m6 A RNA methylation genes were identified in T2DM. There was a U-shaped association between serum IGF2BP3 levels and odds of T2DM in the general Chinese adult population. This study provides important evidence for further examination of the role of m6 A RNA methylation, especially serum IGF2BP3 in T2DM risk assessment.

The Effect of Vitamin D Supplementation on Glycemic Control and Body Mass Index in the Obese, Vitamin D Deficient Adult with Type 2 Diabetes Mellitus: A Systematic Review Protocol

Subclinical left ventricular (LV) dysfunction is prevalent in type 2 diabetes (T2DM). As obesity has been proposed as one causal factor in the disease process, this could bias the reported prevalences. We wanted to characterize echocardiographic LV dysfunction in obese T2DM subjects as compared to non-diabetic obese controls. One hundred patients with T2DM without clinical signs of heart failure (29% females, mean ± SD age 58.4 ± 10.5 years, body mass index (BMI) 30.1 ± 5.5 kg/m(2), blood pressure (BP) 141 ± 18/83 ± 9 mmHg) and 100 non-diabetic controls (29% females) matched for age (58.6 ± 10.5 years), BMI (29.8 ± 4.0 kg/m(2) and systolic BP (140 ± 14 mmHg) underwent echocardiography and color tissue Doppler imaging (TDI). Diastolic function was evaluated with conventional Doppler recordings and early (e') and late (a') myocardial velocities. The ratio between early transmitral filling (E) and the corresponding myocardial tissue velocity (e') served as an index of LV filling pressure. T2DM patients had more concentric hypertrophy with a relative wall thickness of 0.42 ± 0.07 vs controls 0.38 ± 0.07, P < 0.001. The T2DM group had signs of diastolic dysfunction with lower E/A ratio (0.91 ± 0.27 vs. 1.12 ± 0.38, P < 0.001), deceleration time (195 ± 49 vs 242 ± 72 ms, P < 0.001), e' (5.7 ± 2.0 vs. 6.6 ± 1.8 cm/s, P = 0.001), and a' (6.5 ± 2.0 vs. 7.6 ± 1.5 cm/s, P < 0.001) compared to the controls, and higher E/e' (13.3 ± 4.7 vs. 11.1 ± 3.5, P < 0.001). Thus, there were indications of pseudo normalization and increased filling pressure in the T2DM group, whereas the controls had evidence for relaxation abnormalities without elevated filling pressure. Compared to a non-diabetic obese group, more advanced subclinical impairment of diastolic function was seen in T2DM.

Conflicting results have been reported as to the extent that cardiovascular function can be reestablished after rewarming from hypothermia. We measured hemodynamic function, myocardial metabolism and tissue water content in dogs core-cooled to 25 degrees C and later rewarmed. At 25 degrees C left ventricular (LV) systolic pressure (LVSP) was 54% +/- 4%, maximum rate of LV pressure rise (LV dP/dtmax) 44% +/- 5%, aortic pressure (AOP) 50% +/- 6%, heart rate (HR) 40% +/- 0%, cardiac output (CO) 37% +/- 5%, myocardial blood flow (MBF) 34% +/- 5%, and myocardial oxygen consumption (MVO2) 8% +/- 1%, compared to precooling. Stroke volume (SV) and LV end-diastolic pressure (LVEDP) were unchanged. As normothermia (37 degrees C) was reestablished, the depression of cardiac function and myocardial metabolism remained the same as that at 25 degrees C: LVSP 71% +/- 6%, LV dP/dtmax 73% +/- 7%, SV 60% +/- 9%, AOP 70% +/- 6%, CO 57% +/- 9%, MBF 53% +/- 8%, and MVO2 44% +/- 8% HR, in contrast, recovered to precooling values. The arterial concentrations of glucose and free fatty acids (FFA) did not change significantly during the experimental period, whereas an increase in lactate of nonmyocardial origin appeared after rewarming. Increased myocardial contents of creatine phosphate and water were found during both hypothermia and rewarming. The present study demonstrates a persistent depression of cardiac function after hypothermia and rewarming in spite of adequate energy stores. Thus, a direct influence on myocardial contractile function by the cooling and rewarming process is suggested.

Objective To explore the pathophysiological characteristics of myocardial injury model in type 2 diabetes mellitus (T2DM) induced by streptozotocin (STZ) injection after high-fat and high-sucrose feeding. Methods A total of 60 SD rats aged at 8-12 weeks and weighing 180-220 g were divided into normal (Nor) group (n=20), T2DM group (n=20) and insulin group (Ins, n=20) by random number table method. STZ was administrated to rats after 4 weeks of high fat and high sucrose diet or normal diet and followed by another 4 weeks of feeding with the same diet. Blood glucose and insulin levels were monitored, and homeostasis model assessment of insulin resistance (HOMA-IR) was calculated. Hemodynamic parameters were measured using an isolated cardiac perfusion model. The changes of mitochondrial structure were observed with transmission electron microscope. Mitochondrial respiratory function, activity of key enzymes in respiratory chain and ATP content were measured. One way ANOVA was used for statistical analysis. Results A total of 50 SD rats were finally enrolled in Nor group (n=20), T2DM group (n=15) or Ins group (n=15). The HOMA-IR index of T2DM and Ins group were higher than that of Nor group (4.2±0.4, 3.9±0.4, 1.4±0.3, respectively, F=312.3, P<0.01). The +dp/dt max of left ventricle [(3 599±215), (3 123±239), (3 084±200) mmHg/s, F=31.02, P<0.01] and left ventricular development pressure [(102±8), (89±6), (90±7) mmHg, F=14.19, P<0.01, 1 mmHg=0.133 kPa] were superior to those in T2DM group and Ins group. The mitochondrial respiration State 3, respiration control ratio and respiratory chain enzyme activity of Nor group were superior to those of Ins group and T2DM group (F=11.12-505.50, P<0.05); Nor group had more ATP production compared to the other two groups (P<0.01). Conclusion The modeling method used in this study provides the pathophysiologic characteristics of diabetes related myocardial, damages such as cardiac ventricular malfunction, mitochondrial dysfunction, energy metabolism abnormality, as well as hyperglycemia and insulin resistance, which can be used for the studies of cardioprotection of diabetic cardiomyopathy. Key words: Diabetes mellitus, type 2; Myocardium; Mitochondria

Objective To investigate the effect of suberoylanilide hydroxamic acid(SAHA)on sufentanil postconditioning-induced cardioprotection in rats with type 2 diabetes mellitus(T2DM). Methods Male SPF Sprague-Dawley rats, weighing 250-300 g, aged 5-6 weeks, were used in the study.T2DM was induced by high-fat diet (4 weeks) and intraperitoneal 1% streptozotocin 35 mg/kg, and confirmed by fasting blood glucose level≥16.7 mmol/L.Forty rats with T2DM were divided into 5 groups(n=8 each)using a random number table: sham operation group(grou T2DM-S); ischemia-reperfusion group(group T2DM-I/R); sufentanil postconditioning group(group T2DM-SP); SAHA group(group T2DM-SA); SAHA plus sufentanil postconditioning group(group T2DM-SASP). In T2DM-SA and T2DM-SASP groups, SAHA 25 mg/kg was injected intraperitoneally once a day for 5 consecutive days before operation.Their hearts were excised and retrogradely perfused in a Langendorff apparatus.The hearts were subjected to 30 min of global ischemia followed by 120 min of reperfusion to establish the model of ischemia/reperfusion injury.At 30 min of equilibration and 30, 60 and 120 min of reperfusion, the left ventricular systolic pressure(LVSP), heart rate(HR), and the maximum rate of increase and decrease of ventricular pressure(±dp/dtmax)were recorded.At 120 min of reperfusion, the left ventricular mass(LVM)and infarct size(IS)were measured, and IS/LVM ratio was calculated.The expression of glycogen synthesis kinase 3β(GSK-3β)and phosphorylated GSK-3β(p-GSK-3β)in the myocardium was detected by Western blot. Results Compared with group T2DM-S, the LVSP, HR and ±dp/dtmax were significantly decreased, the IS and IS/LVM ratio were significantly increased, and the expression of myocardial p-GSK-3β was significantly down-regulated in group T2DM-I/R(P 0.05). Compared with group T2DM-SP, the ±dp/dtmax was significantly increased, the IS and IS/LVM ratio were significantly decreased, and the expression of myocardial p-GSK-3β was significantly up-regulated in group T2DM-SASP(P<0.05). Conclusion SAHA can improve cardioprotection induced by sufentanil postconditioning to some extent in the rats with T2DM. Key words: Hydroxamic acids; Diabetes mellitus, type 2; Sufentanil; Myocardial reperfusion injury

Objective To evaluate the effect of capsaicin on cardiac dysfunction in diabetic rats using an in vitro experiment. Methods Healthy male Sprague-Dawley rats, weighing 240-260 g, in which type 1 diabetes mellitus was induced by intraperitoneal streptozotocin 50 mg/kg, were studied.Eighteen diabetic rats were selected at 8 weeks after successful establishment of the model and divided into 3 groups (n=6 each) using a random number table: diabetes mellitus group (DM group), capsaicin group (CAP group) and capsaicin plus capsazepine group (CPZ group). Another 8 rats with normal blood glucose served as control group (C group). Rat hearts were quickly removed under deep anesthesia and retrogradely perfused with an oxygen-saturated K-H solution (at 37 ℃) using a Langendorff apparatus.Cardiac function was maintained stable for 10 min.The hearts were continuously perfused with K-H solution for 30 min in C and DM groups.The hearts were perfused with K-H solution for 20 min, and capsaicin (1.4×10-9 g/L) was then infused for 10 min via the branch of aortic cannula using micro pump in CAP group.The hearts were perfused with K-H solution for 10 min, and capsaicin receptor-transient receptor potential vanilloid type 1 antagonist capsazepine (1.4×10-7 g/L) was then infused for 10 min followed by infusion of capsaicin (1.4×10-9 g/L) at 0.5 ml/min for 10 min via the branch of aortic cannula using a micro-pump in CPZ group.Left ventricular systolic pressure (LVSP), left ventricular developed pressure (LVDP), left ventricular end-diastolic pressure (LVEDP), heart rate, the maximum rate of increase or decrease in left ventricular pressure (±dp/dtmax) were recorded at 10, 20 and 30 min of continuous infusion (T1-3). Results There was no significant difference in LVEDP and ±dp/dtmax at each time point among the four groups (P>0.05). Compared with C group, LVSP and LVDP were significantly decreased at T1-3 in DM and CPZ groups and at T1-2 in CAP group, and heart rate was significantly decreased at T1-3 in DM, CPZ and CAP groups (P 0.05). LVSP and LVDP were significantly lower at T3 in CPZ group than in CAP group (P<0.05). Conclusion Capsaicin can mitigate cardiac dysfunction in diabetic rats, and the mechanism is related to activating transient receptor potential vanilloid type 1. Key words: Capsaicin; Diabetes mellitus; Heart function tests

Diabetes mellitus and heart failure: insights from a toxic relationship