Intrinsic chemoresistance to gemcitabine is associated with decreased expression of BNIP3 in pancreatic cancer.

PURPOSE: Although chemotherapy with gemcitabine is a common mode of treatment of pancreatic cancer, 75% of patients do not benefit from this therapy. It is likely that the sensitivity of cancer cells to gemcitabine is determined by a number of different factors. EXPERIMENTAL DESIGN: To identify genes that might contribute to resistance to gemcitabine, 15 pancreatic cancer cell lines were subjected to gemcitabine treatment. Simultaneously, gene expression profiling using a cDNA microarray to identify genes responsible for gemcitabine sensitivity was performed. RESULTS: The pancreatic cancer cell lines could be classified into three groups: a gemcitabine "sensitive," an "intermediate sensitive," and a "resistant" group. Microarray analysis identified 71 genes that show differential expression between gemcitabine-sensitive and -resistant cell lines including 27 genes relatively overexpressed in sensitive cell lines whereas 44 genes are relatively overexpressed in resistant cell lines. Among these genes, 7 genes are potentially involved in the phosphatidylinositol 3-kinase/Akt pathway. In addition to this major signaling pathway, Bcl2/adenovirus E1B 19 kDa protein interacting protein (BNIP3), a Bcl-2 family proapoptotic protein, was identified as being expressed at lower levels in drug-resistant pancreatic cancer cell lines. In an analysis of 21 pancreatic cancer tissue specimens, more than 90% showed down-regulated expression of BNIP3. When expression of BNIP3 was suppressed using small interfering RNA, gemcitabine-induced cytotoxicity in vitro was much reduced. CONCLUSIONS: These results suggest that BNIP3 and the phosphatidylinositol 3-kinase/Akt pathway may play an important role in the poor response to gemcitabine treatment in pancreatic cancer patients.     

Possible enhancing effects of atrazine on growth of 7,12-dimethylbenz(a) anthracene-induced mammary tumors in ovariectomized Sprague-Dawley rats

Atrazine, one of the most commonly used herbicides in the world, has been reported to have endocrine disrupting effects in vivo. In the present experiment, influence of dietary atrazine on the late promotion/progression stage of mammary carcinogenesis in ovariectomized female Sprague-Dawley rats was examined after a single intragastric administration of 7,12-dimethylbenz(a)anthracene (DMBA). When the incidence of palpable mammary tumors reached about 50%, the animals were subjected to ovariectomy and divided into tumor bearing [DMBA-Tumor(+)] and non-tumor bearing [DMBA-Tumor(-)] groups, with subgroups of each fed a soybean-free diet containing 0, 5, 50, or 500 p.p.m. atrazine for 34 weeks. At the completion of the study, the tumor volume in the 50 and 500 p.p.m. treatment Tumor(+) subgroups was greater than in the 0 p.p.m. control case. In the DMBA-Tumor(-) group, higher incidences and volumes of the mammary tumors, with or without statistical significance (P <0.05), were observed in the 50 and 500 p.p.m. subgroups. Atrazine treatment tended to increase proportion of estrogen receptor alpha-positive tumors and stimulated cell proliferation in the DMBA-Tumor(+) group, but with no clear effects on serum hormone levels. The present study indicates that atrazine has a potential for enhancing the growth of mammary tumors, partly through increasing cell proliferation in the promotion/progression stage in female rats under ovarian hormone-free conditions.     

A potent apoptosis-inducing activity of a sesquiterpene lactone, arucanolide, in HL60 cells: a crucial role of apoptosis-inducing factor

Six main sesquiterpene lactones (germacranolides) from Calea urticifolia were evaluated for in vitro cytotoxicity against human tumor cell lines HL60 and SW480 cells. Among them, arucanolide and parthenolide displayed marked cytotoxicity against both cell lines. Arucanolide exhibited a low IC(50) in HL60 cells. The cytotoxic activity of arucanolide was observed at lower concentrations compared to that of parthenolide, which has been reported to be a typical and simple germacranolide. The activity was found to be mainly due to apoptosis that was assessed by morphological findings, DNA ladder formation (24 - 36 h), and flow cytometric analysis in HL60 cells. Western blotting and an apoptosis inhibition assay using caspase inhibitors did not demonstrate the activation of any caspases tested. However, the mitochondrial membrane potential of HL60 cells was lost after 24-h treatment with arucanolide, and concurrently apoptosis-inducing factor (AIF) released from mitochondria was detected by Western blot analysis. The inactivation of nuclear factor-kappaB, which has been commonly shown in parthenolide-induced apoptosis, did not occur in arucanolide-induced apoptosis. Taken together, the findings presented here indicate that arucanolide induced marked apoptosis in HL60 cells mainly by dissipating mitochondrial membrane potential, which would trigger AIF-induced apoptosis.     

Enhanced learning of normal adult rodents by repeated oral administration of soybean transphosphatidylated phosphatidylserine

Soybean lecithin transphosphatidylated phosphatidylserine (SB-tPS) is already known to improve the learning ability of aged or drug-induced amnesic rodents. In this study, its effect on normal adult rodents was evaluated using several learning tasks. Firstly, three behavioral tests (open-field, Y-maze, and active avoidance test) were consecutively carried out after the daily oral administration of SB-tPS (50 mg/kg per day, for 34 days). Repeated oral administration of SB-tPS did not affect either exploratory behavior in the open-field test or spontaneous alternation behavior in the Y-maze test, while mice pretreated with SB-tPS showed significant enhancement of conditioned avoidance response. Secondly, the brightness discrimination test was used to evaluate the effect of SB-tPS on learning ability. The daily oral administration of SB-tPS (50 mg/kg per day, for 27 days) to normal rats significantly increased the correct response ratio in the brightness discrimination test. Finally, to elucidate the necessity of SB-tPS pretreatment, another active avoidance test was carried out, and no enhancement of conditioned avoidance response was observed in non-pretreated mice. These results suggest that repeated administration of SB-tPS could enhance the learning ability of normal adult rodents as those of aged ones.     

Effect of insulin treatment on tissue size of the genitourinary tract in BB rats with spontaneously developed and streptozotocin-induced diabetes

To examine the differences between spontaneous and streptozotocin (STZ)-induced diabetes, four parallel studies were performed; three studies of diabetes-prone BB (BBDP/Wor) rats maintained for 8, 16, and 32 weeks and one study of STZ-injected diabetes-resistant BB (BBDR/Wor) rats maintained for 32 weeks. Each diabetic study has three groups of rats: a control group; a euglycemic group, which received sufficient amounts of insulin; and a hyperglycemic group, which received a suboptimal dose of insulin. The extent of tissue weight changes was generally shown to be less dramatic in the euglycemic diabetic than in the hyperglycemic diabetic rats. STZ-induced diabetes increased the bladder weight more dramatically (up to 3-fold) than did spontaneous diabetes (up to 2-fold). Furthermore, a significant decrease in the size of the adrenal gland (20%) and testis (10%) is observed only with spontaneous diabetes, whereas a significant decrease in the size of the ventral prostate (30%) is observed only with STZ-induced diabetes, although the serum testosterone levels are similar in both groups. Our data demonstrate that there are differences in the effect of insulin treatment on the tissue size of the genitourinary tract between spontaneously developed and streptozotocin-induced diabetes in BB rats.     

Effects of 4-tert-pentylphenol on the gene expression of P450 11beta-hydroxylase in the gonad of medaka (Oryzias latipes)

Alkylphenols including 4-tert-pentylphenol (4-PP) have been shown to alter sexual differentiation in fish due to their estrogenic properties. Medaka (Oryzias latipes) is so sensitive to these substances because morphological sex reversal and testis-ova induction are well developed in the exposed males. However, little work has been done to characterize the molecular effects of estrogenic substances on the morphological and gonadal feminization in male fish. Cytochrome P450 11beta-hydroxylase (P450(11beta)) is a key steroidogenic enzyme in production of 11-ketotestosterone which is the predominant androgen in male fish. In this study, we cloned a cDNA encoding medaka testicular P450(11beta), and then investigated the gene expression of P450(11beta) in the testes of genetically male medaka exposed to 4-PP. The cDNA contains 1740 nucleotides that encode a protein of 543 amino acids, which shares 68.9% and 73.4% homology with testicular P450(11beta)s from Japanese eel (Anguilla japonica) and rainbow trout (Oncorhynchus mykiss), respectively. HeLa cells transfected with an expression vector containing the open reading frame of medaka P450(11beta) cDNA showed 11beta-hydroxylating activity in the presence of exogenous testosterone. Analysis of tissue distribution by RT-PCR showed great abundance of P450(11beta) mRNA in testis. In the partial life-cycle exposure with 4-PP, morphologically sex-reversal was observed in XY medaka exposed to 4-PP concentrations of > or =238 microg/L. Furthermore, exposure to 4-PP completely inhibited P450(11beta) mRNA expression in the gonads of sex-reversed XY fish at 60-day posthatch. These results suggest that xeno-estrogen 4-PP may have inhibitory effects on the synthesis of testicular 11-oxygenated androgens through downregulation of P450(11beta) expression in the genetically male fish.     

Anesthetic management by total intravenous anesthesia with propofol, pentazocine and ketamine

BACKGROUND: The authors evaluated the efficacy of anesthetic management by total intravenous anesthesia with propofol, pentazocine and ketamine. METHODS: Thirty-five patients for mastectomy were anesthetized by propofol, pentazocine and ketamine. Patients were divided into two groups by age; one is patients under 61 years of age and the others are patients above 61 years. Analysis was made retrospectively. Anesthesia was induced with propofol and ketamine and was maintained with propofol infusion and intermittent administration of vecuronium with 40% oxygen in air. Pentazocine was administrated as a bolus dose before incision. RESULTS: There were no differences in the patient background except age and height between the two groups. After induction of anesthesia, systolic and diastolic blood pressures decreased compared with those before induction in both groups. Systolic and diastolic blood pressures and heart rate increased after tracheal intubation, but the hemodynamics remained stable after the start of surgery. The induction and maintenance doses of propofol were not different between the two groups. Patients above 61 years had smaller dosage of pentazocine compared with those in patients under 61 years. The dosage of ketamine was not different between two groups. Awakening time in about 80% of patients was within 15 minutes and is not different between the two groups. Postoperative pain relief was good in both groups. Incidence of nausea and vomiting was 25% and was not the different between the two groups. CONCLUSIONS: Total intravenous anesthesia with propofol, pentazocine and ketamine would be useful to stabilize hemodynamic state, to obtain rapid recovery and to provide effective postoperative pain relief.     

A retrospective study on awareness in 1922 cases during induction of general anesthesia

BACKGROUND: There are some reports on the incidence of awareness during general anesthesia that is usually stable at the maintenance period. The aim of this study is to evaluate the incidence of awareness during the induction period of general anesthesia in which the effects of anesthetics are unstable. METHODS: The research-nurses interviewed the patients, who had undergone general anesthesia, on the awareness during anesthesia within a week after operation. The patients were excluded from the study if they were in deep sedation or unconscious because of the medical reasons. We defined the induction period from the administration of hypnotic drugs to the tracheal intubation. RESULTS: Seven cases with ages from 20 s to 70 s out of 1922 cases were identified as the residual awareness cases during the induction period. Six cases were managed with low concentrations of inhalation anesthetics after injection of intravenous hypnotics. The incidence was lower, but not significant, if they were managed with total intravenous technique. The BIS values were above 60 in all these cases if the monitor was attached. CONCLUSIONS: The incidence of awareness during the induction was 0.36%. We have to pay more attention to the disappearance of the hypnotic effect at the induction period.