902426
The effect of telomerase activity on vascular smooth muscle cell proliferation in type 2 diabetes in vivo and in vitro.
Serious complications as a result of type 2 diabetes mellitus (T2DM) are becoming a major health concern. In the present study, it was hypothesized that telomerase activity is upregulated in vascular smooth muscle cells (VSMCs) during proliferation in T2DM and that the application of telomerase inhibitors impedes the proliferation of VSMCs in vitro. Male Wistar rats were randomly allocated into the normal control (NC) or diabetic (DM) group. Diabetes was induced by high‑fat feeding and a low dose of streptozotocin (STZ; 30 mg/kg). Primary VSMC cultures were exposed to normal (5.5 mM) or high (25 mM) glucose and insulin (100 nM) in the presence and absence of various concentrations of antisense oligoribonucleotides (ASODNs) for varying lengths of time. Telomerase activity and the proliferation of VSMCs were measured. Results showed that there was a significant increase in the levels of fasting glucose, insulin, triglycerides (TG) and free fatty acids (FFAs) in the diabetic group. Telomerase activity and the proliferation of VSMCs were significantly higher in the diabetic group in vivo and in the high glucose and insulin (HGI)-treated group in vitro (P<0.01). ASODNs significantly inhibited the proliferation of VSMCs in a concentration- and time‑dependent manner (P<0.01). In conclusion, hyperglycemia and hyperinsulinemia stimulate telomerase activity and the proliferation of VSMCs, while the inhibition of telomerase activity reduces the proliferation of VSMCs, indicating that telomerase may be involved in the pathological process of diabetic vascular disease.
37087642
Effect of high free fatty acids on the anti-contractile response of perivascular adipose tissue in rat aorta.
To determine whether high free fatty acids (FFA) could affect the anti-contractile properties of perivascular adipose tissue (PVAT) in rat aortas. Wistar rats were divided into normal, obesity and fenofibrate groups and fed a normal, high-fat, and high-fat plus fenofibrate diet, respectively. Thoracic aortas with or without PVAT (PVAT+ and PVAT-) were prepared with either intact endothelium (E+) or with endothelium removed (E-). Aortas pre-treated with either 500μmol/L of palmitic acid (PA) or physiological salt solution (PSS), as a control, were used for in vitro study. Concentration-dependent responses of aortas to norepinephrine were measured. The anti-contractile effects of PVAT were attenuated in both obese rats with high FFA levels and in the PA group in the presence of endothelium, but not in the absence of endothelium. The attenuation of the anti-contractile effect was restored by reducing FFA levels in the fenofibrate group (P<0.05). Incubation of aortas (PVAT+ E+) with nitric oxide (NO) synthase inhibitor and tumor necrosis factor-alpha (TNF-α) in the normal group caused attenuation of the anti-contractile effect of PVAT (P<0.05). Incubation of aortas (PVAT+ E+) in the obese and PA groups with a NO donor, anti-TNF-α antibodies or free radical scavengers partially restored the anti-contractile effect of PVAT (P<0.05). Under both acute and chronic conditions, high FFA levels could attenuate the anti-contractile properties of PVAT by an endothelium-dependent rather than an endothelium-independent mechanism, in which inflammation and oxidative stress may play important roles.
9163230
Effect of Aspirin on the Expression of Hepatocyte NF-κB and Serum TNF-α in Streptozotocin-Induced Type 2 Diabetic Rats
Aspirin is a kind of anti-inflammatory drug and may be used to reverse hyperglycemia, hyperinsulinemia, and dyslipidemia by improving insulin resistance. We hypothesized that aspirin improves insulin resistance in type 2 diabetes by inhibiting hepatic nuclear factor kappa-β (NF-κB) activation and serum tumor necrosis factor-α (TNF-α). Adult male Wistar rats were randomly divided into four groups: control, untreated diabetic, diabetic treated with metformin (100 mg/kg/day), and diabetic treated with aspirin (120 mg/kg/day). Diabetes was induced by high-fat feeding and a low dose of streptozotocin (30 mg/kg). After treatment, plasma glucose, insulin, lipids, free fatty acids (FFAs) concentrations and serum TNF-α were determined. The expression of NF-κB in hepatocytes was analyzed by immunohistochemistry and western blot. The results showed administration of aspirin caused no significant lowering in fasting glucose level but significant reduction of hepatic NF-κB expression and serum TNF-α level with improved insulin resistance compared to the diabetic group. The relevant analysis showed positive correlation between the expression of homeostasis model assessment-insulin resistance (HOMA-IR) and NF-κB (r = 0.799, P < 0.01); HOMA-IR and serum TNF-α (r = 0.790, P < 0.01). It is concluded that aspirin improves insulin resistance by inhibiting hepatic NF-κB activation and TNF-α level in streptozotocin-induced type 2 diabetic rats.
25270885
Poly(ethylene glycol)-functionalized devices for electric field gradient focusing.
Electric field gradient focusing (EFGF) is an equilibrium gradient focusing technique that depends on an electric field gradient and a hydrodynamic counterflow to focus, concentrate, and separate charged analytes. In this work, EFGF devices were fabricated from poly(ethylene glycol) (PEG)-functionalized acrylic plastic. The separation channel was formed in an ionically conductive and protein-resistant PEG-functionalized hydrogel, which was cast in a changing cross-sectional cavity in the plastic device. A linear electric field gradient was obtained by applying a voltage lengthwise across the shaped hydrogel. Standard proteins were used as analytes to demonstrate the performance of these EFGF devices. With an increase in counterflow rate or decrease in applied voltage, analyte bands broadened, but resolution increased in agreement with theory. To reduce analyte band dispersion and improve focusing performance, a protein-compatible PEG-functionalized monolith was incorporated in the EFGF channel. Compared with focusing in an open channel, protein bands in the monolith-filled EFGF channel were significantly narrower.
19099233
Intramuscular delivery of antiangiogenic genes suppresses secondary metastases after removal of primary tumors
The success of surgery to remove primary tumors can be compromised by the subsequent outgrowth of metastases. It is recognized that primary tumors secrete antiangiogenic factors that suppress the outgrowth of their daughter metastases. In accord we show here that surgical removal of primary EL-4 lymphomas led to a marked decrease in the levels of circulating angiostatin and endostatin, and promoted the growth of distant nodular tumors. Expression vectors encoding angiostatin and endostatin, formulated with poly-N-vinyl pyrrolidone (PVP), were injected into the tibialis and gastrocnemia muscles, leading to expression of angiostatin and endostatin in muscle fibers. High levels of biologically active exogenous proteins were secreted into the circulation. Intramuscular gene therapy with angiostatin and endostatin plasmids significantly inhibited tumor vascularity and induced tumor cell apoptosis, and thereby suppressed the growth of secondary subcutaneous and disseminated metastatic tumors in the lung and liver. Simultaneous intramuscular delivery of both angiostatin and endostatin plasmids significantly prolonged the survival of mice after removal of primary tumors. These results suggest that intramuscular gene transfer of angiostatin and endostatin might serve as a prophylactic cancer-prevention strategy to combat the recurrence of cancer after surgical resection of primary tumors.
36944421
Effect of burn injury on glucocorticoid receptor binding activity in rat muscle.
Burn injury is associated with increased muscle proteolysis and up-regulated gene expression in the proteolytic pathway. Glucocorticoids (GCs) are the most important mediator of burn injury induced muscle cachexia. However, the understanding of the mechanisms of GCs action in response to burn injury remains elusive. It is well known that GC acts by binding its own receptor. Therefore, in the present study, we examined the influence of burn injury on the hormone binding activity of the glucocorticoid receptor (GR) in skeletal muscle. Burn injury resulted in increased hormone binding activity in extensor digitorum longus (EDL) and soleus muscles. Scatchard plots revealed that the increased GR hormone binding activity reflected increased numbers of hormone binding sites, whereas receptor affinity for GCs was unchanged. Western blot analysis showed that dissociation of GR/heat shock protein 90 heterocomplex or increase in GR protein may account for the effect of burn injury. The GR antagonist RU 38486 blocked the burn injury-induced increase in GR hormone binding activity, implicating a positive regulatory effect of GCs on GR binding activity under the present experimental conditions.
23441457
Meta-analysis of randomized trials for health care interventions: one for all?
Meta-analysis of randomized trials stands at the top of the epidemiological designs to test the effect of health care interventions. Ideally, it systematically and comprehensively collects the relevant randomized trials, and pools the trials to generate a single estimate of effects. However, the rationale for meta-analysis may not always be thoughtfully considered, and overlooking underlying principles may cause illusions. This article revisits the rationale for meta-analysis, discusses how meta-analysis can be misleading, and summarizes approaches to critically and judiciously interpret and use the results of meta-analysis.
24997000
Preparation of phenylboronic acid functionalized cation-exchange monolithic columns for protein separation and refolding.
In this study, we described a simple and effective modification procedure to prepare poly (methacrylate-co-ethylene glycol dimethacrylate) monolithic columns functionalized with 3-aminophenylboronic acid. The column morphology, pore size and specific surface area of the fabricated monolith were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, and mercury intrusion porosimeter, respectively. The frontal analysis was carried out for dynamic loading capacity of the model protein on the modified column. The chromatographic performance of the cation-exchange monolith was evaluated through separating a mixture of five proteins such as lysozyme, cytochrome c, ribonuclease A, trypsin and bovine serum albumin and one-step purification of lysozyme from egg whites, and the expected results were obtained. In addition, the functionalized column was used to refold ribonuclease A and cytochrome c, and this procedure was monitored by circular dichroism and fluorescence spectroscopy. Compared with the conventional dilution refolding method, the ion-exchange chromatography refolding method developed here is more effective for specific bioactivity recovery.