Organocatalytic silyl transfer from silylborane to nitroalkenes for the synthesis of ß-silyl nitroalkanes and ß-silyl amines.

The silylation of a wide array of nitroalkenes is achieved by organocatalysts in yields up to 93%. The reaction is carried out in a toluene/water biphasic solvent under operationally simple conditions. Reduction of the nitro group provides efficient access to functionalized ß-silyl amines.

Ultrasound reverses multidrug resistance in human cancer cells by altering gene expression of ABC transporter proteins and Bax protein.

Multidrug resistance (MDR) is the major obstacle to successful chemotherapy of human malignancies and strategies for overcoming MDR phenomena are still unavailable to clinical use. Previous results showed that ultrasound (US) exposure could make MDR cancer cells become more sensitive to anticancer drugs, and the physical parameters of US exposure could adjust the uptake and retention of rhodamine 123 in MDR cells. In this study, we investigated the mechanisms of therapeutic ultrasound as a physical approach to overcoming MDR in a multidrug resistant human hepatocarcinoma cell line (HepG2/ADM). Our results demonstrated that the percentage of P-glycoprotein(+) (P-gp), multidrug resistance-associated protein(+) (MRP) and lung resistance-related protein(+) (LRP) cells was 96.97% ± 2.41%, 20.84% ± 3.12% and 1.16% ± 0.59% in HepG2/ADM cells, and 62.84% ± 3.42%, 10.26% ± 1.18% and 3.05% ± 0.37% in US-exposed HepG2/ADM cells, respectively. A significant decrease in the number of P-gp(+) and MRP(+) cells was observed between US-exposed HepG2/ADM and HepG2/ADM cells (p < 0.05). Using RT-PCR technique, we found that US could significantly downregulate the expression of P-glycoprotein (P-gp) and (MRP) at the mRNA level in HepG2/ADM cells. Compared with the control, the percentage of apoptotic cell death was significantly increased in HepG2/ADM after ultrasound exposure. Using immunocytochemistry, the percentage of Bcl-2(+) and Bax(+) cells was 21.7% and 4.1% in the control, and 18.46% and 8.1% in the US-exposed cells, respectively. The percentage of Bax(+) cells was significantly higher in US-exposed HepG2/ADM cells (p < 0.05), suggesting that US exposure could lead to cellular apoptosis in HepG2/ADM cells. It is concluded that US exposure could reverse MDR in HepG2/ADM cells via decreasing P-gp and MRP levels and their mRNA expressions and increasing expression of Bax protein. It may lead to the development of a novel strategy of using a targeted, noninvasive physical approach for the induction of MDR reversal in cancer cells.

[Repairing effects of low-intensity pulsed ultrasound on alveolar bone defects in Beagle dogs].

OBJECTIVE: To evaluate the potential repairing effects of low-intensity pulsed ultrasound (LIPUS) irradiation on acute horizontal alveolar bone defects at the mandibular pre-molar areas in Beagle dogs. METHODS: Horizontal alveolar bone defect models were established under enamelo-cemental junction 6 mm at the mandibular third and forth pre-molar buccal regions on both sides in 4 beagle dogs, and bilateral sides of each dog were randomly divided into two groups: Experimental groups with LIPUS irradiation (I(SATA) 30 mW X cm(-2), 20 min x d(-1)) and control groups without opening power source of LIPUS radiation. Dual energy X-ray bone densitometer was used to detect the bony density after an 8 weeks' irradiation. Meanwhile, decalcified bone tissue sections were used to assess the histological effects of new alveolar bone. RESULTS: The results of new bony density detection in experimental group and control group were (0.6053 +/- 0.0566) g x cm(-2), (0.6047 +/- 0.0552) g x cm(-2), respectively, and there was no statistical significance between the differences of the two groups (P = 0.9839). Hematoxylin-eosin staining of decalcified bone tissue sections demonstrated that there were more osteoblasts lining at the edge of new alveolar bone in the experimental groups than that scattered in the control groups, and Masson staining revealed that collagens in new alveolar bone stained bright red indicating higher maturity in the experimental groups, while in the control groups mainly stained blue with some virescent areas indicating lower maturity. CONCLUSION: LIPUS irradiation on acute horizontal alveolar bone defects has potential repairing effects.

Optimization of ultrasound-mediated in vitro reversal of multidrug resistance in human hepatocarcinoma cell line HepG2.

Previous studies have shown that ultrasound (US) could enhance cellular uptake and cytotoxicity of chemotherapeutic agents in drug-resistant cancer cells. The goal of this study was to investigate the optimization of physical parameters of US exposure for in vitro reversal of multidrug resistance (MDR) in human hepatocarcinoma cell line (HepG2). Using a constant total energy density (3.87 J/cm(2)) that could maintain cell viability at the 90% level, we exposed parent (HepG2) and MDR variant (HepG2/ADM) tumor cells to US in vitro to a variety of US frequency, exposure intensity and duty cycle. After US exposure, flow cytometry was performed to measure retention of rhodamine 123 (Rh123) in both HepG2 and HepG2/MDR cells. The results showed that US frequency and duty cycle (DC) could influence the intracellular retention of Rh123 in HepG2/ADM tumor cells; intensity and exposure duration appeared to be of little importance. At a constant total energy density of 3.87 J/cm(2), the optimal US parameters for in vitro reversal of MDR in HepG2/ADM tumor cells appear to be 0.8 MHz, 0.43 W/cm(2) and 60% DC, respectively. These findings support our hypothesis that varying the physical parameters would have an effect on efficiency of US-mediated reversal of MDR in cancer cells.

Cytotoxic effects and in vitro reversal of multidrug resistance by therapeutic ultrasound in human hepatocarcinoma cell line (HepG2).

Multidrug resistance (MDR) is one of the major obstacles to successful chemotherapy of human malignancies. Although many strategies have been explored to overcome MDR, none of them have been proven to be clinically useful until now. The aim of this study was to investigate whether a novel therapeutic ultrasound (US) approach would have useful effects on the reversal of MDR in cancer cells. Wild-type and MDR phenotype (HepG2/ADM) cells of the human hepatocarcinoma cell line HepG2 were exposed to 0.8 MHz US at an intensity of 0.43 W/cm(2) for a 9s exposure (total energy density: 3.87 J/cm(2)). After US exposure, cell number and viability were counted immediately, and flow cytometry was performed to measure retention of rhodamine 123 and adriamycin in HepG2 and HepG2/MDR cells. Both cell lines were then incubated in suspension with adriamycin, vincristine, etoposide, cisplatin and 5-fluorouracil, respectively, and the MTT assay was used to determine cytotoxicity. The results showed that US exposure could significantly increase the uptake of Rh123 and ADM by HepG2/ADM tumor cells. The resistant index for the chemotherapeutic drugs was significantly lower in the US-exposed HepG2/ADM cells than in those not exposed to US. It was therefore concluded that US exposure could enhance the sensitivity of HepG2/ADM tumor cells to these chemotherapeutic agents, and the functional and structural changes induced by previous US exposure in MDR tumor cells may be responsible for it. However, further study is needed to investigate the mechanism behind US-mediated reversal of MDR.

[Short and long-term efficacy of focused ultrasound therapy for vulva dystrophy].

OBJECTIVE: To investigate the short and long-term efficacy and complications, as well as the influential factors of focused ultrasound for the treatment of vulva dystrophy. METHODS: Seventy-six eligible patients with vulva dystrophy were randomized and treated with focused ultrasound between 1999 and 2002. Among them, 45 patients were with squamous hyperplasia (SH) and 31 patients were with lichen sclerosus (LS). Colposcopic examination and biopsies were used to monitor and evaluate the changes. Statistical analysis was performed using chi(2) (McNemar chi(2)) test. RESULTS: The median follow-up period was 28.3 month (range 24 months to 60 months). Complete remission (CR) occurred in 39 of 76 patients (27 SH and 12 LS). The cure rate was 51% at four years. The response rate was 95% (72/76). Four of the 76 patients (2 SH and 2 LS) had slight skin burn and a few blisters around the labia 2-4 hours after treatment. Moreover, two patients (1 SH and 1 LS) had superficial ulcers on the treated vulva skin two weeks after ultrasound treatment, which were cured without any complications with local anti-inflammatory drugs for 2-3 weeks. No other long-term side effects were found after a follow up for 24-60 months. The total recurrence rate at four years was 36% (26/72), all of whom were treated again with ultrasound therapy with good results and no complications. There was no obvious difference among the different anaesthesia types and pathological types of the lesions (P > 0.05). However, the shorter the history of the disease, the better the efficacy of the treatment. The younger the patient was, the better the efficacy of the treatment. CONCLUSIONS: Vulva dystrophy can be treated with focused ultrasound effectively and safely. This approach appears to be a new promising treatment method.

Development and characterization of multidrug resistant human hepatocarcinoma cell line in nude mice.

AIM: To establish a multidrug resistant (MDR) cell sub-line from the human hepatocarcinoma cell line (HepG2) in nude mice. METHODS: HepG2 cell cultures were incubated with increasing concentrations of adriamycin (ADM) to develop an ADM-resistant cell subline (HepG2/ADM) with cross-resistance to other chemotherapeutic agents. Twenty male athymic BALB/c-nu/nu mice were randomized into HepG2/nude and HepG2/ADM/nude groups (10 in each group). A cell suspension (either HepG2 or HepG2/ADM) was injected subcutaneously into mice in each group. Tumor growth was recorded, and animals were sacrificed 4-5 wk after cell implantation. Tumors were prepared for histology, and viable tumor was dispersed into a single-cell suspension. The IC50 values for a number of chemotherapeutic agents were determined by 2, 3-bis (2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide inner salt (MTT) assay. Rhodamine-123 retention/efflux and the level of resistance-associated proteins were determined by flow cytometry. The mRNA expression of mdr1, mrp and lrp genes was detected using reverse transcriptase polymerase chain reaction (RT-PCR) in HepG2/nude and HepG2/ADM/nude groups. RESULTS: The appearances of HepG2/nude cells were slightly different from those of HepG2/ADM/nude cells. Similar tumor growth curves were determined in both groups. A cross-resistance to ADM, vincristine, cisplatin and 5-fluorouracil was seen in HepG2/ADM/nude group. The levels of P-glycoprotein and multidrug resistance-associated proteins were significantly increased. The mRNA expression levels of mdr1, mrp and lrp were higher in HepG2/ADM/nude cells. CONCLUSION: ADM-resistant HepG2 subline in nude mice has a cross resistance to chemotherapeutic drugs. It may be used as an in vivo model to investigate the mechanisms of MDR, and explore the targeted approaches to overcoming MDR.

[Establishment of in vivo adriamycin-induced multidrug resistance models of subcutaneous and hepatic transplanted human liver cancer in nude mice].

BACKGROUND & OBJECTIVE: Multidrug resistance (MDR) phenotype is the obstacle of chemotherapy in tumors and inspired research interesting. This study was to establish multidrug resistance (MDR) models induced with adriamycin in vivo of subcutaneous or in situ hepatic transplanted human liver cancer in nude mice (BALB/C nu/nu), and explore the biological characteristics and mechanism of multidrug resistance, which can provide an ideal animal model for the basic,and clinical study of MDR. METHODS: After successful performing either subcutaneous or hepatic transplantation in nude mice with liver cancer cell line HepG2, adriamycin (ADM) was injected into abdominal cavity to induce multidrug resistance. The chemosensitivity of HepG2 and ADM-cultured HepG2 cells was determined by MTT assay. P-glycoprotein (P-gp), multidrug resistance-associated protein (MRP), lung resistance-related protein (LRP), and cell pump-efflux to Rhodamine 123 (R123) were determined by flow cytometry. The mRNA expression of P-gp, MRP, and LRP was assessed with reverse transcriptase polymerase chain reaction(RT-PCR). RESULTS: Most biological characteristics of either subcutaneous or hepatic transplanted HepG2 liver cancer in nude mice like the parent HepG2 liver cancer. Both of them showed significant multidrug resistance. Among them, the resistance index of ADM was 26.4 times in hepatic transplanted group, and 24.6 times in subcutaneous transplanted group higher than that of parent cell line HepG2. In subcutaneous,and hepatic transplanted ADM-cultured groups, P-gp [(77.3+/-2.1)%, and (78.1+/-1.9)%], MRP [(72.1+/-4.3)%, and (72.7+/-5.0)%], and LRP [(31.1+/-1.0)%, and (32.2+/-1.4)%] positive cells increased significantly, their mRNA positive expression increased also, and the cell pump-efflux to R123 strengthened. However, no significant difference of above data was observed between subcutaneous,and hepatic transplanted tumor group (P >0.05). CONCLUSION: Both MDR subcutaneous and hepatic HepG2 transplanted models induced by in vivo injection of adriamycin in nude mice have the same biological characteristics as parent HepG2 liver cancer. These 2 animal models could be used as in vivo MDR models to explore the mechanism of MDR and reversing therapeutic methods.

[Establishment of human hepatocellular carcinoma multidrug-resistance cell line (HepG2/Adm) and study apoptosis induced by low-frequency pulse ultrasound exposure].

OBJECTIVE: To establish human hepatocellular carcinoma multidrug-resistance cell line (HepG2/ADM) and to determine the effect of low-frequency pulse ultrasound (US) on MDR cells and investigate its mechanism. METHODS: Using gradual increase of adriamycin (ADM) concentrations in culture, an adriamycin-resistant human hepatocellular carcinoma cell sub line (HepG2/ADM) was established in vitro. HepG2/ADM cells were cultured in vitro and randomly divided into 4 groups: the control group (HepG2/ADM only), the group ADM by 1.0 mug/ml adriamycin for 1 h, the group US by low-frequency pulse ultrasound for 10 min, and the group US by low-frequency pulse ultrasound and treated with adriamycin simultaneously at same time. A sonication at a frequency of 0.8 MHz, was delivered with an intensity level of 0.5W/cm2, with continuous exposure of 10 min was applied. The ability of US to induce the apoptosis of MDR was evaluated by analyses of fluorescence microscopy, DNA fragmentation assay and flow cytometry assay. RESULTS: HepG2/Adm was resistant to many anti-tumor agents, and its IC50 of ADM was 26 times higher than that of parent cell line HepG2. Significant over expressions of P-gp, MRP, LRP and GSTs were detected. HepG2/ADM cells radiated by US had the typical characteristics of apoptosis. Compared with the control group (HepG2/ADM, 3.47%); the apoptosis rates were higher in US (12.23%). The therapeutic alliance of US with ADM for MDR cells, have a significant change in the ratio of apoptosis (18.81%, t=1.46 to 5.36, P<0.01). CONCLUSION: HepG2/ADM could have the biological characteristics of human multidrug-resistance cell line. The US sonication of 0.8 MHz could induce apoptosis of HepG2/ADM cell in vitro, and could act synergistically with Adriamycin.