Adenoviral vectors capable of replication improve the efficacy of HSVtk/GCV suicide gene therapy of cancer. (17/1229)

A major obstacle to the success of gene therapy strategies that directly target cancer cells is the poor vector distribution within solid tumors. To address this problem, we developed an E1b 55 kDa attenuated, replication-competent adenovirus (Ad.TKRC) which expresses the herpes simplex-1 thymidine kinase (HSVtk) gene to sensitize tumors to ganciclovir (GCV). Efficacy of this combined strategy was tested in nude mice with subcutaneous human A375 melanoma and ME180 cervical carcinomas. Intratumoral injection of a replication-defective adenoviral vector expressing HSVtk (Ad.TK) followed by GCV treatment resulted in doubling of the survival time of mice bearing A375 tumors and 20% long-term survival of mice with ME180 tumors. Treatment of tumors with Ad.TKRC without GCV resulted in a similar antitumor effect, confirming that the replicating vector has an oncolytic effect. When GCV was initiated 3 days after Ad.TKRC injection, survival of mice with each tumor type was greatly prolonged, with 60% of animals with ME180 tumors surviving for over 160 days. These results confirm that both the oncolysis caused by a replicating virus and suicide/prodrug gene therapy with HSVtk/GCV have potent antitumor effects. When combined, these two approaches are complementary resulting in a significantly improved treatment outcome.  (+info)

Effective and safe gene therapy for colorectal carcinoma using the cytosine deaminase gene directed by the carcinoembryonic antigen promoter. (18/1229)

We have recently isolated carcinoembryonic antigen (CEA) promoter regions consisting of 419 bp and 204 bp from CEA-producing human colorectal carcinoma (CRC). We constructed CEA419/CD and CEA204/CD retroviruses carrying the bacterial cytosine deaminase (CD) gene directed by the CEA promoter regions. pCD2 retroviruses carrying the CD gene directed by the retrovirus long terminal repeat promoter were also used. CEA419/CD or CEA204/CD retrovirus-infected CRC cells were found to be susceptible to 5-fluorocytosine (5-FC), while non-CRC cells infected with the same retroviruses were not. CD-transduced CRC xenografts in nude mice were sensitive to 5-FC treatment, resulting in arrest of tumor growth. When mice with intraperitoneally disseminated CRCs were given intraperitoneal injections of CEA419/CD retrovirus-producing cells followed by 5-FC treatment, significantly prolonged survival rates were observed compared with animals injected with pCD2 retrovirus-producing cells followed by 5-FC treatment. Importantly, bone marrow suppression was not observed in animals injected with CEA419/CD retrovirus-producing cells and 5-FC, while profound bone marrow suppression was observed in those injected with pCD2 retrovirus-producing cells and 5-FC. These results indicate that effective and safe in vivo gene therapy for advanced CRC may be feasible by transferring the CD gene controlled by the CEA promoter followed by 5-FC treatment.  (+info)

Bleomycin stimulates lung epithelial cells to release neutrophil and monocyte chemotactic activities. (19/1229)

Although bleomycin, an antineoplastic drug, is used in the treatment of a variety of tumors, the mechanisms of bleomycin-induced lung injury and fibrosis are not fully elucidated. We postulated that bleomycin might stimulate A549 cells, a type II pneumocyte cell line, to release neutrophil and monocyte chemotactic activities (NCA and MCA, respectively). To test this hypothesis, A549 cell supernatant fluids were harvested and evaluated for NCA and MCA. A549 cell supernatant fluids showed NCA and MCA in response to bleomycin in a dose- and time-dependent manner (P < 0.05). Checkerboard analysis revealed that both NCA and MCA were predominantly chemotactic. Partial characterization of the released NCA and MCA showed that the activities were partially heat labile, trypsin digested, and predominantly ethyl acetate extractable. Lipoxygenase inhibitors and cycloheximide inhibited the release of chemotactic activities significantly. Molecular-sieve column chromatography revealed that the released activities were heterogeneous. However, low-molecular-weight activity was prominent. Leukotriene B4-receptor antagonist, anti-interleukin-8, anti-granulocyte colony-stimulating factor, and anti-monocyte chemoattractant protein-1 antibodies attenuated the chemotactic activities. Immunoreactive leukotriene B4 receptor, interleukin-8, granulocyte colony-stimulating factor, and monocyte chemoattractant protein-1 significantly increased in supernatant fluids in response to bleomycin. These data demonstrate that bleomycin stimulates type II epithelial cells to release chemotactic activities and plays a role in inflammatory cell recruitment into the lung.  (+info)

Vibrissae-evoked behavior and conditioning before functional ontogeny of the somatosensory vibrissae cortex. (20/1229)

The following experiments determined that the somatosensory whisker system is functional and capable of experience-dependent behavioral plasticity in the neonate before functional maturation of the somatosensory whisker cortex. First, unilateral whisker stimulation caused increased behavioral activity in both postnatal day (P) 3-4 and P8 pups, whereas stimulation-evoked cortical activity (14C 2-deoxyglucose autoradiography) was detectable only in P8 pups. Second, neonatal rat pups are capable of forming associations between whisker stimulation and a reinforcer. A classical conditioning paradigm (P3-P4) showed that the learning groups (paired whisker stimulation-shock or paired whisker stimulation-warm air stream) exhibited significantly higher behavioral responsiveness to whisker stimulation than controls. Finally, stimulus-evoked somatosensory cortical activity during testing [P8; using 14C 2-deoxyglucose (2-DG) autoradiography] was assessed after somatosensory conditioning from P1-P8. No learning-associated differences in stimulus-evoked cortical activity were detected between learning and nonlearning control groups. Together, these experiments demonstrate that the whisker system is functional in neonates and capable of experience-dependent behavioral plasticity. Furthermore, in contrast to adult somatosensory classical conditioning, these data suggest that the cortex is not required for associative somatosensory learning in neonates.  (+info)

Combined effect of Interceed and 5-fluorouracil on delayed adjustable strabismus surgery. (21/1229)

AIMS/BACKGROUND: To discover a more reliable method of performing delayed suture adjustment as a basis to investigate whether delayed adjustment actually provides more stable results. In order to prevent the formation of postoperative adhesions and delay the time of adjustment, an animal study was performed to determine the combined effect of physical barriers, Viscoat and Interceed, and a pharmacological agent, 5-fluorouracil (5-FU). METHODS: 38 rabbit eyes were divided into three groups. After recession of the superior rectus muscle (SRM), 5-FU was applied beneath and over the SRM in group 5-FU. Group I-f had Interceed and 5-FU and group I-fv, Interceed, 5-FU, and Viscoat. Delayed adjustment was performed once on each SRM at 1, 2, and 3 weeks postoperatively. The possible length and the necessary force to adjust as well as the degree of adhesions were recorded. RESULTS: 5-FU delayed the adjustment for up to 1 week after surgery in three out of four eyes. Combined use of Interceed and 5-FU could delay the adjustment for up to 1 week after surgery in three out of five eyes. Addition of Viscoat could delay the adjustment for up to 1 week after surgery in four out of five eyes. Adjustment was possible on only one of four eyes thereafter. CONCLUSIONS: Combined use of Interceed, 5-FU, and Viscoat could delay the adjustment in rabbits until 1 week postoperatively.  (+info)

Risk factors for failures of trabeculectomies performed without antimetabolites. (22/1229)

AIMS: To assess the risk profile for the failure of trabeculectomies in a large group of patients who were selected to be operated on without the use of antimetabolites. This was done in an effort to find subgroups of patients who may not need antimetabolites for primary procedures. METHODS: Consecutive patients scheduled for routine trabeculectomies were operated during a 4 year period and were followed up for at least 6 months postoperatively. Patients were regularly examined in the glaucoma unit and by their local ophthalmologists. Pre- and postoperative data were evaluated and success rates determined. RESULTS: 709 eyes of 566 patients were operated on; 534 eyes of 534 patients (94.4%) were finally evaluated. The mean follow up was 27.9 (SD 13.6) months with a range of 6-62 months. Success rates for complete surgical success ranged from 59% in the best group with pigmentary dispersion syndrome to 0% in the worst group with neovascular glaucoma. Success rates of patients with POAG, pseudoexfoliation, chronic angle closure, pigmentary dispersion syndrome, and dysgenetic glaucoma were similar. Failure rates ranged from 11% in the best group (pseudoexfoliation) to 80% in the worst group (neovascular glaucoma). Failure rates were high in complicated forms of glaucoma such as traumatic (30%), buphthalmus (40%), and uveitic (50%). For repeat trabeculectomies, the failure rate was 49% (20 of 41 eyes). The mean time until failure ranged from 2.7 months (traumatic) to 15.5 months (pigmentary dispersion syndrome) and was 4.9 months for repeat trabeculectomies. CONCLUSION: Trabeculectomy performed in selected groups of patients has a favourable outcome without the use of antimetabolites. It may be possible to avoid antimetabolites in these groups of patients for primary procedures.  (+info)

In vivo effects of ascorbate and glutathione on the uptake of chromium, formation of chromium(V), chromium-DNA binding and 8-hydroxy-2'-deoxyguanosine in liver and kidney of osteogenic disorder shionogi rats following treatment with chromium(VI). (23/1229)

Several previous in vitro studies have indicated that ascorbate and glutathione are the major reductants of Cr(VI) in cells. In order to evaluate the in vivo effects of ascorbate and glutathione on Cr(VI)-induced carcinogenesis, Cr uptake and the formation of Cr(V), Cr-DNA adducts and 8-hydroxy-2'-deoxyguanosine (8-OH-dG) were measured in the liver and kidney of Osteogenic Disorder Shionogi (ODS) rats that lack the ability to synthesize ascorbate. Despite a 10-fold difference in tissue ascorbate levels among different dietary ascorbate groups, the Cr(V) signal intensity, Cr uptake and total Cr-DNA binding were not affected in either organ. Treatment of ODS rats with Cr(VI) (10 mg/kg) had no substantial effect on the levels of ascorbate and glutathione in these tissues. The levels of Cr(V) and Cr-DNA binding were approximately 2-fold higher in the liver than in the kidney, although the levels of total Cr uptake were similar in both tissues. Cr uptake levels were significantly lower in the liver and kidney of ODS rats treated with high levels of ascorbate and a high dose of Cr(VI) (40 mg/kg), suggesting a detoxifying role played by plasma ascorbate. Similarly, modulation of glutathione levels by N-acetyl-L-cysteine, L-buthionine-S, R-sulfoximine or phorone in these animals by up to 2-fold had little or no consistent effect on Cr uptake, Cr-DNA binding, Cr(V) levels or 8-OH-dG formation in either organ. One possible explanation is that reduction of ascorbate and glutathione concentration to <10 and 50%, respectively, of normal in these two organs still provides threshold levels of these two reductants that are in excess of what is needed for significant reductive activation of Cr(VI). Alternatively, it is possible that ascorbate and glutathione do not play a major role in the formation of Cr(V), Cr-DNA binding or 8-OH-dG and that other cellular reductants, such as cysteine or other amino acids, might be more important reductants of Cr(VI) in vivo.  (+info)

Swainsonine protects both murine and human haematopoietic systems from chemotherapeutic toxicity. (24/1229)

The haematopoietic system is sensitive to cytotoxic damage and is often the site of dose-limiting toxicity. We previously reported that swainsonine, an inhibitor of protein glycosylation, reduced the bone marrow toxicity resulting from a single dose of anticancer drugs in otherwise healthy mice. However, more important questions are (1) can swainsonine protect tumour-bearing mice without interfering with the anti-tumour effects of the drugs, and (2) can swainsonine stimulate haematopoietic activity of human, as well as murine, bone marrow. We demonstrate here that swainsonine protects C57BL/6 mice bearing melanoma-derived tumours from cyclophosphamide-induced toxicity without interfering with the drug's ability to inhibit tumour growth. Similar results were obtained in vivo with 3'-azido-3'-deoxythymidine (AZT), a myelosuppressive agent often used in therapy for acquired immune deficiency syndrome. Swainsonine increased both total bone marrow cellularity and the number of circulating white blood cells in mice treated with doses of AZT that typically lead to severe myelosuppression. Swainsonine also increased the number of erythroid and myeloid colony forming cells (CFCs) in short-term cultures of murine bone marrow, restoring the number of progenitor cells to the control level in the presence of AZT doses that reduced CFCs by 80%. With respect to the sensitivity of human haematopoietic cells to swainsonine, we show that swainsonine protected human myeloid progenitor cells from AZT toxicity in vitro. These results suggest that swainsonine may be useful as an adjuvant in several types of human chemotherapy.  (+info)