Induction of apoptosis in multi-drug resistant (MDR) human glioblastoma cells by SN-38, a metabolite of the camptothecin derivative CPT-11

 The overexpression of the multidrug resistance (mdr1) gene and its product, P-glycoprotein (P-gp), is thought to limit the successful chemotherapy of human tumors. Recent studies demonstrate that SN-38, a metabolite of the camptothecin (CPT) derivative CPT-11, has antitumor effects on several tumors, but the mechanisms responsible for its cytotoxicity remain unclear. We therefore determined whether SN-38 has cytotoxic effects on MDR human glioblastoma GB-1 cells and non-MDR human glioblastoma U87-MG cells. Furthermore, we determined what role SN-38 plays in the induction of cytotoxicity in these tumor cells. In this study, we demonstrated that SN-38 had significantly stronger antitumor effects on GB-1 and U-87MG cells than did CPT (P<0.01 and P<0.05, respectively). In addition, findings obtained using a DNA fragmentation assay, Hoechst 33258 staining, in situ end-labeling and cell cycle analysis demonstrated that SN-38 induced apoptosis in these tumors. Our results suggest that SN-38 has a stronger antitumor effect on malignant glioma cells regardless of MDR expression than does CPT, and therefore can be considered a new chemotherapeutic agent potentially effective in the treatment of human primary or recurrent malignant gliomas resistant to chemotherapy. Received: 6 October 1995/Accepted 29 June 1996     

Relationship between Tissue Concentrations of Polycyclic Aromatic Hydrocarbons and DNA Adducts in Green-Lipped Mussels (Perna viridis)

Green-lipped mussels (Perna viridis) were collected from a site in Hong Kong which is relatively free from polycyclic aromatic hydrocarbon (PAH) contamination, and maintained in situ at this and three other sites with different degrees of PAH contamination. The transplanted mussels were retrieved after a 30-day field exposure. DNA adducts in the gill tissues were quantified, and tissue concentrations of benzo[a]pyrene as well as total PAHs (with potential carcinogenicity) determined for individual mussels. Results indicate that (1) tissue concentration of PAHs and adduct levels in mussels collected from a single site can be highly variable; and (2) adduct levels were related to tissue concentrations of benzo[a]pyrene as well as total PAHs of individual animals.     

A precarious pregnancy involving a patient with a large placental chorioangioma: a case report

Chorioangiomas are common placental neoplasms that are primarily asymptomatic, but the larger subtypes have a variable presentation and can result in severe pregnancy complications. We report a case of a pregnant patient who presented with a 10 x 12 x 10 cm placental chorioangioma at 32 weeks, despite an unremarkable ultrasound at 28 weeks. Since these more substantial chorioangiomas can induce fetal mortality, close surveillance with perinatology and neonatology consultation is necessary to enhance the probability of a favorable patient prognosis.     

Inhibiting effect of antisense hTRT on telomerase activity of human liver cancer cell line SMMC-7721

Objective: To induce changes in biological character of human liver cancer cell line SMMC-7721 by blocking the expression of telomerase genes hTRT and to explore its value in cancer gene therapy. Methods: The vehicle for eukaryotic expression of antisense hTRT was constructed and then transfected into SMMC-7721 cells. The effects of antisense hTRT gene on telomerase activity, cancer cell growth and malignant phenotypes were analyzed. Results: The obtained transfectants that could express antisense hTRT gene stably showed marked decrease in telomerase activity;the shortening of telomere was obvious; cells presented contact growth inhibition; in nude mice transplantation, the rate of tumor induction dramatically decreased. Conclusion : Antisense hTRT gene expression can significantly inhibit telomerase activity of cancer cells and decrease malignant phenotypes in vitro and in vivo. Therefore, as a telomerase inhibitor, antisense hTRT gene may be a new pathway for cancer therapy.     

乙型肝炎病毒基因异质性及准种特点研究的临床意义

乙型肝炎病毒（HBV）基因组在慢性HBV感染的个体中存在不同的基因型（genotype)、血清型（serotype)和准种（quasispecies)等基因序列异质性（heterogeneity)的特点。HBV基因序列异质性是普遍存在的，在HBV基因组的各结构基因区、调节基因区都有异质性的特点，而且始终处在持续变化之中。HBV基因序列的异质性具有十分重要的生物医学意义。HBV准种等异质性特点的研究，使我们对于HBV全基因序列、HBV基因突变的规律、HBV抗药性的遗传学基础，甚至导致肝细胞恶性转化的分子生物学机制等都有了全新的认识。准种概念的引入，使我们对于HBV基因序列异质性的认识，从单一病毒株水平提升到HBV种群的水平，是对于HBV基因遗传与变异认识的一次革命性的飞跃。     

Deep Venous Thrombosis in Lap Band Surgery: A Single Center Study

Bariatric surgery has been demonstrated to be an effective treatment for morbid obesity. The purpose of this study is to investigate the incidence of pre- and post-operative deep venous thrombosis (DVT) in Lap-Band surgical patients. This study group comprised 56 consecutive patients who underwent Lap-Band surgery. Mean age and body mass index were 38 years (range: 18–64 years) and 50.9 kg/m² (range: 53–74 kg/m²), respectively. All the patients were screened with duplex ultrasonography pre- and post-operatively. There were no iliac, femoral, or popliteal vein thromboses detected at any given point of time. No patient had any clinical signs or symptoms of DVT post-operatively. There were no observable differences attributable to DVT prophylaxis. This data suggest that in the setting of chemical and mechanical prophylaxis, the incidence of DVT in patients undergoing Lap-Band surgery at an established bariatric centre is minimal.