甲硫氨酸维生素B_1对妊娠期肝内胆汁淤积症模型大鼠的治疗作用

目的探讨甲硫氨酸维生素B1针（甲维比）对妊娠期肝内胆汗淤积症（intrahepatic cholestasis of pregnancy,ICP）模型大鼠的治疗作用。方法妊娠大鼠48只,随机分为正常妊娠组、模型组、甲维比高剂量组2ml/（kg·d）、甲维比中剂量组1ml/（kg·d）、甲维比低剂量组0.5ml/（kg·d）、腺苷蛋氨酸组100mg/（kg·d）。从其妊娠第12天开始肌内注射苯甲酸雌二醇2.5mg/（kg·d）,连续6d,同时给药1周。正常妊娠组与模型组均肌注等容积蒸馏水。检测大鼠血清总胆红素（TBIL）、丙氨酸氨基转移酶（ALT）、总胆汁酸（TBA）、雌二醇（E2）水平;并比较各组大鼠肝脏组织病理变化;运用免疫组化法测定大鼠肝组织Th1细胞因子及核因子NF-κB的表达。结果甲维比高、中剂量治疗组及腺苷蛋氨酸组均较模型组大鼠流产率、胚胎致死率显著降低（P〈0.01）,大鼠血清TBIL、ALT、TBA、E2水平也降低（P〈0.01）,Th1细胞因子及核因子NF-κB的表达下调（P〈0.01）,大鼠的肝脏病理变化得到较大改善。结论甲维比可通过降低模型大鼠肝组织Th1细胞因子及核因子NF-κB的表达对ICP模型大鼠发挥明显的治疗作用。     

Sarcolipin and phospholamban as regulators of cardiac sarcoplasmic reticulum Ca2+ ATPase

The cardiac sarcoplasmic reticulum calcium ATPase (SERCA2a) plays a critical role in maintaining the intracellular calcium homeostasis during cardiac contraction and relaxation. It has been well documented over the years that altered expression and activity of SERCA2a can lead to systolic and diastolic dysfunction. The activity of SERCA2a is regulated by two structurally similar proteins, phospholamban (PLB) and sarcolipin (SLN). Although, the relevance of PLB has been extensively studied over the years, the role SLN in cardiac physiology is an emerging field of study. This review focuses on the advances in the understanding of the regulation of SERCA2a by SLN and PLB. In particular, it highlights the similarities and differences between the two proteins and their roles in cardiac patho-physiology.     

Effect of reduced temperature on glycoprotein (Ig, HLA) processing and transport in lymphoid cells

Secretion of Igs and surface expression of HLA antigens was examined in lymphoid cells as a function of temp. Upon reducing the temp from 37 to 20 degrees C a progressive decrease in the secretion of Ig and surface expression of HLA antigens was noted. When the status of the oligosaccharides present on these glycoproteins was examined, conversion of high-mannose [endo-beta-N-acetylglucosaminidase-(Endo H) sensitive] to complex-type (Endo H resistant) oligosaccharides diminished with decreasing temp. At no time was an accumulation of Endo H resistant glycoproteins seen intracellularly. These results show that the phenomenon observed for synthesis and intracellular transport of viral glycoproteins in epithelial cells at reduced temp, namely intracellular accumulation of viral glycoproteins carrying complex sugar moieties, does not necessarily apply to glycoprotein transport in lymphoid cells. A difference in subcellular organization of epithelial and lymphoid cells may be responsible for this discrepancy.     

Small molecule inhibitors of methionine aminopeptidase type 2 (MetAP-2) fail to inhibit endothelial cell proliferation or formation of microvessels from rat aortic rings in vitro

The protein processing enzyme, methionine aminopeptidase-2 (MetAP-2), has been identified as a molecular target of fumagillin and its derivative, TNP-470, compounds known to inhibit endothelial cell proliferation and angiogenesis. A high-throughput screening program was undertaken to identify selective, reversible inhibitors of MetAP-2 in an attempt to discover structurally novel anti-angiogenic agents for potential therapeutic use in oncology. Approximately 90 small-molecule, reversible, selective inhibitors of rhMetAP-2 were identified. The most potent of these compounds contained a singly-substituted triazole moiety which exhibited an IC₅₀ of 8 nM (95% confidence limits 5 to 13 nM) and was highly selective for MetAP-2 over MetAP-1 ( 60-fold difference in IC₅₀ values). Unlike fumagillin, these MetAP-2 inhibitors failed to significantly inhibit growth factor-stimulated endothelial cell (HUVEC) proliferation or to suppress angiogenesis in the in vitroaortic ring explant model of microvessel outgrowth. The MetAP-2-inhibitory activity of these compounds was dependent on the divalent cation used as the metalloenzyme activating cofactor for MetAP-2. These inhibitors were identified using cobalt(II)-activated recombinant human MetAP-2 for screening compound libraries. When manganese (Mn²⁺) was substituted for cobalt following EDTA treatment and extensive dialysis of the MetAP-2 protein, these inhibitors were significantly less potent (40-fold increase in IC₅₀) as inhibitors of MetAP-2. These results support the recent hypothesis that cobalt may not be the relevant divalent metal ion cofactor for MetAP-2 in cells and may explain the observed absence of cell-based activity using potent triazole inhibitors of cobalt-activated MetAP-2     

Transforming growth factor‐α attenuates hepatic fibrosis: possible involvement of matrix metalloproteinase‐1

Background: The effect of transforming growth factor (TGF)‐α on fibrosis varies between cell types and the role of TGF‐α in hepatic fibrosis has not been fully elucidated. Methods: We examined the effect of TGF‐α on hepatic fibrosis using TGF‐α‐expressing transgenic mice fed a methionine‐ and choline‐deficient (MCD) diet and human hepatic stellate cells (HSCs) line LX‐2, rat and human primary HSCs. Results: Although the expression levels of the tissue inhibitor of metalloproteinases‐1 and α1(I) collagen mRNA were unchanged, feeding the TGF‐α transgenic mice the MCD diet resulted in greater expression of the murine functional analogue of matrix metalloproteinase‐1 (MMP‐1), MMP‐13 mRNA and protein and attenuated hepatic fibrosis compared with wild‐type mice. TGF‐α overexpression did not affect the extent of the steatosis, oxidative stress and hepatic inflammation in the MCD diet‐fed mice. The effect of TGF‐α on the fibrogenic and anti‐fibrogenic gene expressions varied between cell types in vitro. TGF‐α increased MMP‐1 mRNA expressions that were completely blocked by gefitinib in LX‐2 cells. The extracellular signal‐regulated kinase (ERK) 1/2, c‐Jun N‐terminal kinase and p38 pathways were involved in MMP‐1 mRNA expression in LX‐2 cells. Although TGF‐α increased the phosphorylation of p38, the p38 inhibitor activated the RAS‐ERK pathway and increased TGF‐α‐induced MMP‐1 mRNA expression, which suggested that there may be a crosstalk between the RAS‐ERK and the p38 pathways in LX‐2 cells. Conclusions: The TGF‐α may attenuate hepatic fibrosis in part because of upregulation of the expression of MMP‐1. The balance between fibrogenic and anti‐fibrogenic gene expression and between the activity of the RAS‐ERK and the p38 pathways may be crucial for the fibrotic process.     

MTHFR和MTRR基因多态性与急性脑梗死的关联分析

目的探讨亚甲基四氢叶酸还原酶(MTHFR)、甲硫氨酸合成酶还原酶(MTRR)基因多态性与急性脑梗死(ACI)的关联。方法以130例ACI患者为病例组,130例体检健康者为健康对照组,PCR-荧光探针法对两组人群MTHFR基因677CT、1298AC位点和MTRR基因66AG位点的多态性进行定性检测,分析两组人群的基因型及其分布,酶法检测血清同型半胱氨酸(Hcy)水平。结果与健康对照组比较,ACI组MTHFR 677CT的T等位基因频率、MTRR 66AG的G等位基因频率显著升高(χ~2=21.03,P0.01和χ~2=12.45,P0.01),而MTHFR 1298AC差异无统计学意义(P0.05)。此外,与健康对照组比较,ACI组血清Hcy明显升高(P0.01),血清Hcy水平在MTHFR 677CT、MTHFR 1298AC及MTRR 66AG的基因型间差异具有统计学意义(P0.05)。结论 MTHFR 677 T等位基因、MTRR 66 G等位基因与ACI密切相关,MTHFR 1298AC未发现与ACI相关,3位点SNP均与ACI患者Hcy水平升高有关。     

Long-term safety of lamivudine treatment in patients with chronic hepatitis B

BACKGROUND & AIMS: Data on the long-term safety of lamivudine are limited. The aim of this analysis was to determine the incidence of hepatitis flares, hepatic decompensation, and liver-disease-related (LDR) serious adverse events (SAE) during long-term lamivudine treatment. METHODS: We reviewed data on 998 patients with HBeAg-positive compensated chronic hepatitis B who received lamivudine for up to 6 years (median, 4 years) and 200 patients who received placebo for 1 year. RESULTS: Hepatitis flares occurred in 10% of the lamivudine-treated patients in year 1 and in 18%-21% in years 2-5. A temporal association between hepatitis flares and lamivudine-resistant mutations increased from 43% in year 1 to >80% in year 3. Ten hepatic decompensation events occurred in 8 (<1%) lamivudine-treated patients. Fifty-three (5%) lamivudine-treated patients experienced a total of 60 LDR SAEs. Four patients died, 2 from liver-related causes. The proportion of patients with a documented lamivudine-resistant mutation increased from 23% in year 1 to 65% in year 5. During each year of the study, patients with lamivudine-resistant mutations experienced significantly more hepatitis flares than patients without lamivudine-resistant mutations (P < 0.005). The occurrence of hepatic decompensation (0%-2%) and LDR SAEs (1%-10%) among patients with lamivudine resistance remained stable during the first 4 years with mutations and increased afterward to 6% (P = 0.03) and 20% (P = 0.009), respectively. CONCLUSIONS: This study demonstrated that lamivudine treatment for up to 6 years has an excellent safety profile in patients with HBeAg-positive compensated liver disease, but patients with long-standing lamivudine-resistant mutations may experience worsening liver disease.