Sihai Zhao

Diet-induced central obesity and insulin resistance in rabbits.

The present study was designed to examine whether rabbits fed a diet containing high fat and sucrose could develop obesity and insulin resistance (IR), the major pathophysiological features of metabolic syndrome. Male Japanese white rabbits were fed either a normal chow diet (control) or high fat and sucrose diet (HFSD) for 36 weeks. Plasma levels of triglycerides (TG), total cholesterol (TC), glucose and insulin were measured. To evaluate glucose metabolism, we performed an intravenous glucose tolerance test. In addition, we compared adipose tissue accumulation in HFSD-fed rabbits with that in normal rabbits. HFSD constantly and significantly led to an increase in body weight of HFSD-fed rabbits, caused by significantly higher visceral adipose tissue accumulation. Although there were no differences in plasma TG, TC, glucose, insulin levels and blood pressure between the two groups, HFSD-fed rabbits showed impaired glucose clearance associated with higher levels of insulin secretion compared to control rabbits. Our results showed that HFSD induced IR and increased adipose accumulation in rabbits, suggesting that HFSD-fed rabbits may become a model for research on human IR and obesity.

Expression Systems and Species Used for Transgenic Animal Bioreactors

Transgenic animal bioreactors can produce therapeutic proteins with high value for pharmaceutical use. In this paper, we compared different systems capable of producing therapeutic proteins (bacteria, mammalian cells, transgenic plants, and transgenic animals) and found that transgenic animals were potentially ideal bioreactors for the synthesis of pharmaceutical protein complexes. Compared with other transgenic animal expression systems (egg white, blood, urine, seminal plasma, and silkworm cocoon), the mammary glands of transgenic animals have enormous potential. Compared with other mammalian species (pig, goat, sheep, and cow) that are currently being studied as bioreactors, rabbits offer many advantages: high fertility, easy generation of transgenic founders and offspring, insensitivity to prion diseases, relatively high milk production, and no transmission of severe diseases to humans. Noticeably, for a small- or medium-sized facility, the rabbit system is ideal to produce up to 50 kg of protein per year, considering both economical and hygienic aspects; rabbits are attractive candidates for the mammary-gland-specific expression of recombinant proteins. We also reviewed recombinant proteins that have been produced by targeted expression in the mammary glands of rabbits and discussed the limitations of transgenic animal bioreactors.

Matrine inhibits matrix metalloproteinase-9 expression and invasion of human hepatocellular carcinoma cells

Matrine is the major active component of the traditional Chinese medicine Sophora flavescens, but the molecular mechanisms of matrine on tumor invasion inhibition remain unclear. The aim of this study is to elucidate the effects of matrine on invasion ability of human hepatocellular carcinoma (HCC) cells, matrix metalloproteinase-9 (MMP-9), and nuclear factor (NF)-kappa B expression. The expression activity of MMP-9 was measured by reverse transcription polymerase chain reaction, Western blot, and gelatin zymography analysis. The expression of NF-kappa B was measured by the Western blot analysis. Matrine significantly inhibited MMP-9 expression of SMMC-7721 cells. NF-kappa B inhibitor PTDC induced a marked reduction in MMP-9 expression, and it suggested that NF-kappa B could play an important role in MMP-9 expression. Furthermore, matrine significantly suppressed NF-kappa B expression and the invasion of SMMC-7721 cells. Our results showed that matrine inhibited MMP-9 expression and the invasion of human HCC cells. The inhibitory effects are partly associated with the downregulation of the NF-kappa B signaling pathway.

The effects of rosiglitazone on aortic atherosclerosis of cholesterol-fed rabbits

INTRODUCTION Thiazolidinedione (TZD) is widely used a drug for the treatment of type 2 diabetes and protects against cardiovascular events in human. However, it is not clear whether TZD can directly inhibit the progression of atherosclerosis. To test the hypothesis whether administration of TZD could reduce the development of atherosclerosis, we studied the effects of rosiglitazone on aortic atherosclerosis of rabbits fed a cholesterol diet. MATERIALS AND METHODS Male Japanese White rabbits were fed a diet containing either 0.3% cholesterol diet (control group, n=10) or 0.3% cholesterol with rosiglitazone (TZD-treated group, n=12) for 16 weeks. We compared the plasma lipids and the extent of aortic atherosclerosis between two groups. RESULTS AND CONCLUSIONS TZD treatment significantly resulted in the reduction of aortic atherosclerosis by 21% in the aortic arch (p<0.01), 20% in the thoracic aorta (p=0.14), and 28% in the abdominal aorta (p=0.25), without affecting the plasma levels of triglycerides, total cholesterol, high-density lipoprotein cholesterol, glucose and insulin. Immunohistochemical staining showed that the cellular components (macrophages and smooth muscle cells) of the lesions of TZD-treated rabbits were unchanged compared to those of control rabbits. In addition, TZD treatment also led to dramatic improvement of fatty liver in cholesterol-fed rabbits. Our results suggest that the activation of PPARgamma can be beneficial for the treatment of atherosclerosis and fatty liver independent upon the improvement of plasma lipids and glucose metabolism.

A comparison of peginterferon α-2a and α-2b for treatment-naive patients with chronic hepatitis C virus: A meta-analysis of randomized trials

BACKGROUND The standard treatments for chronic infection with the hepatitis C virus (HCV) are peginterferon α-2a or α-2b plus ribavirin, but it remains unclear if one has a better efficacy and safety profile. OBJECTIVE The aim of this study was to perform a meta-analysis of randomized controlled trials (RCTs) comparing peginterferon α-2a and α-2b (in combination with ribavirin) treatments for chronic HCV. METHODS The Cochrane Central Register of Controlled Trials, MEDLINE, Science Citation Index, and EMBASE were searched (1966-April 2010) to identify RCTs that evaluated the sustained virologic response (SVR) to peginterferon α-2a and peginterferon α-2b in patients with chronic HCV. The inclusion criteria were: RCT studies designed to compare the therapeutic effects of peginterferon α-2a (180 μg/wk) and peginterferon α-2b (1.5 μg/kg/wk) for treatment-naive patients with chronic HCV; patients treated for ≥24 weeks if infected with HCV genotypes 2 or 3 and for ≥48 weeks if infected with genotypes 1 or 4, with 24-week follow-ups; and publications written in any language. Reports of duplicated studies were excluded by examining the author list, parent institution, sample size, and results. The primary outcome was the SVR, and the other measures included the liver-related morbidity, all-cause mortality, and adverse events leading to treatment discontinuation. RESULTS The literature search yielded 5580 studies, and 7 RCTs comprising 3212 patients matched the inclusion/exclusion criteria. Overall, the SVR rate was significantly higher in patients treated with peginterferon α-2a than in patients treated with peginterferon α-2b (50% vs 46%, respectively; relative risk [RR] = 1.11; 95% CI, 1.02-1.20; P < 0.05) and varying levels of ribavirin treatment. The subgroup analysis found that, in patients with genotypes 1 or 4, the difference between SVR rate in patients treated with peginterferon α-2a and patients treated with peginterferon α-2b was not statistically significant (43% vs 39%; RR = 1.25; 95% CI, 0.99-1.57). A significantly higher SVR rate was achieved in the HCV patients with genotypes 2 or 3 treated with peginterferon α-2a compared with the patients treated with peginterferon α-2b (86% vs 77%; RR = 1.11; 95% CI, 1.02-1.22; P = 0.02). The meta-analysis of adverse events leading to treatment discontinuation revealed no significant differences between the 2 treatments. CONCLUSIONS The evidence reviewed in this meta-analysis suggests that peginterferon α-2a treatment was associated with a higher SVR rate than peginterferon α-2b treatment in patients with chronic HCV also treated with ribavirin. However, the available evidence on adverse events was insufficient to make recommendations.

Hydrogen sulfide inhibits development of atherosclerosis through up-regulating protein S-nitrosylation.

Hydrogen sulfide (H2S) is an important gaseous signaling molecule that serves many important regulatory roles in physiological and pathophysiological conditions. H2S exerts an anti-atherosclerotic effect through mediating the biological functions of nitric oxide (NO). However, its mechanism of action is unclear. The purpose of this study is to explore the effect mechanism of H2S on the development of atherosclerosis with regard to protein S-nitrosylation. A total of 45 male apoE-/- mice were randomly divided into three groups. Atherosclerosis was induced by Western diet (21% fat and 0.15% cholesterol) with/without administration of a H2S donor (NaHS) or an endogenous cystathionine γ-lyase inhibitor (d, l-propargylglycine) for 12 weeks. After 12 weeks, plasma lipid and plasma NO levels were measured. Aortic gross lesion area and histopathological features of aortic lesion were determined. Additionally, the level of S-nitrosylated proteins in vascular smooth muscle cells (VSMCs) was detected using immunofluorescence in aorta. Rat VSMCs were performed in an in vitro experiment. Inducible nitric oxide synthase (iNOS) protein expression, NO generation, protein S-nitrosylation, and cell proliferation and migration were measured. We found that H2S significantly reduced the aortic atherosclerotic lesion area (P=0.006) and inhibited lipid and macrophage accumulation (P=0.004, P=0.002) and VSMC proliferation (P=0.019) in apoE-/- mice. H2S could up-regulate levels of plasma NO and protein S-nitrosylation in aorta VSMCs. However, d, l- propargylglycine had the opposite effect, increasing the lesion area and the content of lipids and macrophages in the lesions of apoE-/- mice and down-regulating plasma NO levels and protein S-nitrosylation in aorta VSMCs. In vitro experiments, H2S could significantly reverse the reduction of iNOS expression and NO generation induced by oxidized low-density lipoprotein in VSMCs. Moreover, H2S could increase the protein S-nitrosylation level of VSMCs in a dose-dependent manner, and the effect could be inhibited by iNOS inhibitors. In addition, proliferation and migration of VSMCs could be inhibited by H2S in a dose-dependent manner, which could be blocked by an iNOS inhibitor or protein S-nitrosylation removal agent. Our data suggest that H2S could inhibit the development of atherosclerosis by up-regulating plasma NO and protein S-nitrosylation, thereby inhibiting the proliferation and migration of VSMCs.

Expression of TRPV1 in rabbits and consuming hot pepper affects its body weight

The capsaicin receptor, known as transient receptor potential vanilloid subfamily member 1 (TRPV1), is an important membrane receptor that has been implicated in obesity, diabetes, metabolic syndrome and cardiovascular diseases. The rabbit model is considered excellent for studying cardiovascular and metabolic diseases, however, the tissue expression of TRPV1 and physiological functions of its ligand capsaicin on diet-induced obesity have not been fully defined in this model. In the current study, we investigated the tissue expression of TRPV1 in normal rabbits using real-time RT-PCR and Western blot analysis. Rabbit TRPV1 mRNA was highly expressed in a variety of organs, including the kidneys, adrenal gland, spleen and brain. A phylogenetic analysis showed that the amino acid sequence of rabbit TRPV1 was closer to human TRPV1 than rodent TRPV1. To examine the effect of capsaicin (a pungent compound in hot pepper) on body weight, rabbits were fed with either a high fat diet (as control) or high fat diet containing 1% hot pepper. We found that the body weight of the hot pepper-fed rabbits was significantly lower than the control group. We conclude that the intake of capsaicin can prevent diet-induced obesity and rabbit model is useful for the study of TRPV1 function in cardiovascular and metabolic diseases.

Probucol and cilostazol exert a combinatorial anti-atherogenic effect in cholesterol-fed rabbits

INTRODUCTION Probucol (PB) and cilostazol (CZ) both exhibit anti-atherogenic effects. However, their combinatorial effects are unclear. This study was designed to investigate their combinatorial anti-atherogenic effect in cholesterol-fed rabbits. MATERIALS AND METHODS Rabbits were fed a cholesterol diet with PB or CZ alone or both PB and CZ for 16 weeks. The plasma levels of total cholesterol, LDL-cholesterol, HDL-cholesterol, C-reactive protein, superoxide dismutase, malondialdehyde, and nitric oxide (NO) were measured. The aortic atherosclerotic lesions were grossly and microscopically evaluated. Additionally, in vitro experiments were conducted using human umbilical vein endothelial cells. RESULTS AND CONCLUSION We found that the PB group and the PB+CZ group exhibited a reduction in the lesion areas (70% in the PB+CZ group, 56% in the PB group) compared with the vehicle group. However, although PB alone and PB+CZ led to a reduction in the lesion size, the histological analysis revealed that only PB+CZ significantly decreased the macrophage accumulation and smooth muscle cell proliferation in the lesions compared with the vehicle group. The plasma levels of total cholesterol in the PB+CZ group were decreased compared with the vehicle group, Moreover, PB+CZ exerted obvious anti-oxidant and anti-inflammatory effects. Interestingly, the PB+CZ treatment led to a marked increase in the levels of plasma NO. The in vitro experiments showed that the combinatorial treatment up-regulated the levels of NO and protein S-nitrosylation in endothelial cells treated with oxidized LDL. In summary, these results suggest that PB and CZ exert combinatorial anti-atherogenic effects.

Interferon plus Chinese herbs are associated with higher sustained virological response than interferon alone in chronic Hepatitis C: a meta-analysis of randomised trials.

BACKGROUND/AIMS Traditional Chinese herbal therapies are widely used for the treatment of chronic hepatitis C (CHC) in Asia. The aim of this study was to perform a meta-analysis of randomised controlled trials (RCTs) comparing interferon therapies with Chinese herbal therapies and/or interferon plus Chinese herb therapies for the treatment of CHC. METHODS The Cochrane Central Register of Controlled Trials, Medline, Science Citation Index, EMBASE, China National Knowledge Infrastructure, Wanfang Database and China Biomedical Database were searched to identify RCTs that evaluated the virological response to interferon therapies, Chinese herbal therapies and interferon plus Chinese herb therapies in CHC patients. We statistically combined data using a random-effect meta-analysis according to the intention-to-treat principle. RESULTS The literature search yielded 770 studies, and 26 RCTs comprising 1905 patients matched the selection criteria. Overall, the sustained virological response (SVR) was significantly higher in patients treated with interferon plus Chinese herbs than in patients treated with interferon alone (49% vs 33%, relative risk, 1.52; 95% confidence interval: 1.23-1.89; p<0.05). Combined therapies of interferon plus Chinese herb therapies were also superior to interferon therapies alone in achieving the end-of-treatment viral response (ETVR), and resulted in fewer relapses, fewer adverse events and more rapid alanine transaminase normalisation. Interferon therapies achieved higher ETVR than Chinese herbal therapies, but they yielded a similar SVR. CONCLUSIONS The current evidence suggests that combined therapies of interferon plus Chinese herbs yielded a higher SVR, and resulted in fewer relapses and fewer adverse events than interferon therapies.

Protein Inhibitor of Activated STAT3 Suppresses Oxidized LDL-induced Cell Responses during Atherosclerosis in Apolipoprotein E-deficient Mice

Atherosclerosis is a serious public health concern. Excessive inflammatory responses of vascular cells are considered a pivotal pathogenesis mechanism underlying atherosclerosis development. It is known that Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) signalling plays an important role in atherosclerosis progression. Protein inhibitor of activated STAT3 (PIAS3) is the key negative regulator of JAK/STAT3 signalling. However, its effect on atherogenesis is unknown. Here, we observed that PIAS3 levels are reduced in atherosclerotic lesions and that PIAS3 expression decreases in conjunction with increases in interleukin-6 expression and atherosclerosis severity. Oxidized low-density lipoprotein (ox-LDL), an atherogenic stimulus, reduced PIAS3 expression, an effect that may be attributed to nitric oxide synthesis upregulation. In turn, PIAS3 overexpression effectively suppressed ox-LDL-induced inflammation, lipid accumulation and vascular smooth muscle cell proliferation. These results indicate that PIAS3 is a critical repressor of atherosclerosis progression. The findings of this study have contributed to our understanding on the pathogenesis of atherosclerosis and have provided us with a potential target through which we can inhibit atherosclerosis-related cellular responses.