New role for L-arginine in regulation of inducible nitric-oxide-synthase-derived superoxide anion production in raw 264.7 macrophages.

Dietary supplementation with L-arginine was shown to improve immune responses in various inflammatory models. However, the molecular mechanisms underlying L-arginine effects on immune cells remain unrecognized. Herein, we tested the hypothesis that a limitation of L-arginine could lead to the uncoupled state of murine macrophage inducible nitric oxide synthase and, therefore, increase inducible nitric-oxide-synthase-derived superoxide anion formation. Importantly, we demonstrated that L-arginine dose- and time dependently potentiated superoxide anion production in bacterial endotoxin-stimulated macrophages, although it did not influence NADPH oxidase expression and activity. Detailed analysis of macrophage activation showed the time dependence between LPS-induced iNOS expression and increased O(2)(∙-) formation. Moreover, downregulation of macrophage iNOS expression, as well as the inhibition of iNOS activity by NOS inhibitors, unveiled an important role of this enzyme in controlling O(2)(∙-) and peroxynitrite formation during macrophage stimulation. In conclusion, our data demonstrated that simultaneous induction of NADPH oxidase, together with the iNOS enzyme, can result in the uncoupled state of iNOS resulting in the production of functionally important levels of O(2)(∙-) soon after macrophage activation with LPS. Moreover, we demonstrated, for the first time that increased concentrations of L-arginine further potentiate iNOS-dependent O(2) (∙-) formation in inflammatory macrophages.

The multidrug transporter ABCG2 (BCRP) is inhibited by plant-derived cannabinoids.

BACKGROUND AND PURPOSE: Cannabinoids are used therapeutically for the palliation of the adverse side effects associated with cancer chemotherapy. However, cannabinoids also inhibit both the activity and expression of the multidrug transporter, P-glycoprotein in vitro. Here we address the interaction of cannabinol (CBN), cannabidiol (CBD) and delta 9-tetrahydrocannabinol (THC) with the related multidrug transporter, ABCG2. EXPERIMENTAL APPROACH: Cannabinoid inhibition of Abcg2/ABCG2 was assessed using flow cytometric analysis of substrate accumulation and ATPase activity assays. The cytotoxicity and chemosensitization by cannabinoids was determined with cell viability assays. Expression of cannabinoid and vanilloid receptors was assessed using reverse transcriptase polymerase chain reaction, and cannabinoid modulation of ABCG2 expression was examined using immunoblotting. KEY RESULTS: CBN, CBD and THC increased the intracellular accumulation of the Abcg2/ABCG2 substrate, mitoxantrone, in an over-expressing cell line. The THC metabolite, (-)-11-nor-9-carboxy-delta 9-THC was much less potent. The plant cannabinoids inhibited both basal and substrate stimulated ATPase activity of human ABCG2. Cannabinoid cytotoxicity occurred in the absence of known cannabinoid cell surface receptors, and only at concentrations higher than those required for Abcg2/ABCG2 inhibition. Sub-toxic concentrations of the cannabinoids resensitized the overexpressing cell line to the cytotoxic effect of Abcg2/ABCG2 substrates, mitoxantrone and topotecan. This occurred in the absence of any effect on ABCG2 expression. CONCLUSIONS AND IMPLICATIONS: Cannabinoids are novel Abcg2/ABCG2 inhibitors, reversing the Abcg2-mediated multidrug-resistant phenotype in vitro. This finding may have implications for the co-administration of cannabinoids with pharmaceuticals that are ABCG2 substrates.

Acarbose in the treatment of elderly patients with type 2 diabetes.

AIMS: To study the effect of acarbose, an alpha-glucosidase inhibitor, on glycemic control in elderly patients with type 2 diabetes. METHODS: Elderly patients with type 2 diabetes treated with diet alone were randomly treated in a double-blind fashion with placebo (n=99) or acarbose (n=93) for 12 months. RESULTS: After 12 months of therapy, there was a statistically significant difference in the change in glycated haemoglobin (HbA(1c)) (-0.6%) in the acarbose group versus placebo, as well as in the incremental post-prandial glucose values (-2.1 mmol h/l) and mean fasting plasma glucose (-0.7 mmol/l). Although there was no effect of acarbose on insulin release, there was a clear effect of acarbose to decrease relative insulin resistance (-0.8) (HOMA method). In addition, acarbose was generally well tolerated and safe in the elderly; most discontinuations were due to gastrointestinal side effects such as flatulence and diarrhea. There were no cases of hypoglycemia reported, and no clinically relevant changes in laboratory abnormalities or vital signs during the study. CONCLUSIONS: Acarbose improves the glycemic profile and insulin sensitivity in elderly patients with type 2 diabetes who are inadequately controlled on diet alone.

Authentication of medicinal Dendrobium species by the internal transcribed spacer of ribosomal DNA.

Herba Dendrobii (Shihu) is a commonly used Chinese medicine derived from the stem of several orchid species belonging to the genus Dendrobium. It is rather expensive and adulteration is frequent. Proper authentication of the medicinal species is necessary to protect consumers and support conservation measures. DNA sequences of the internal transcribed spacer 2 (ITS 2) of 16 Dendrobium species were shown to be significantly different from one another by an average of 12.4% and from non-orchids and Pholidota (an adulterant of Shihu) by 29.8% and 18.8%, respectively. The intra-specific variation among the Dendrobium species studied was only about 1%. Therefore, ITS 2 regions could be adopted as a molecular marker for differentiating medicinal Dendrobium species from one another and also from non-orchids and adulterants.

Activity of high-dose toremifene plus cisplatin in platinum-treated non-small-cell lung cancer: a phase II California Cancer Consortium Trial.

PURPOSE: Although cisplatin is an important agent in non-small-cell lung cancer (NSCLC), de novo resistance is common and acquired resistance emerges rapidly during therapy. Proposed mediators of platinum resistance include the protein kinase C (PKC) signal transduction pathway and associated c-FOS overexpression. While estrogen administration has been reported to upregulate PKC and c-FOS expression, the triphenylethylenes tamoxifen and toremifene potentiate platinum cytotoxicity by inhibition of PKC. Downregulation of c-FOS expression has been reported to result from PKC inhibition. In view of these findings, we hypothesized that toremifene would reverse platinum resistance and that this interaction would be influenced by tumor estrogen receptor (ER) status. MATERIALS AND METHODS: A phase II trial of high-dose toremifene (600 mg orally daily on days 1-7) plus cisplatin (50 mg/m2 intravenously on days 4 and 11) every 28 days in NSCLC patients was conducted. A group of 30 patients with metastatic NSCLC who had been previously treated with platinum-based therapy were enrolled. RESULTS: All of the 30 patients were assessable for toxicity and 28 for tumor response. Therapy was well tolerated with minimal hematologic and non-hematologic toxicity. Common toxicity criteria grade 3 hematologic toxicity was seen in only three patients. Five patients achieved a partial response for an overall response rate of 18% (95% CI 6-37). Median overall survival was 8.1 months (95% CI 5.4-17). To assess PKC, ER, and c-Fos expression by immunohistochemistry, 12 informative pretreatment patient tumor specimens were obtained. Four patient tumor specimens were positive for one or both PKC isoforms (alpha and epsilon) while c-Fos was overexpressed in three. None of the responding patient tumors exhibited c-FOS or PKC-epsilon overexpression. ER expression was found to be infrequent (8%), contrasting with previous reports in this tumor type. CONCLUSION: While this phase II study indicates that high-dose toremifene plus cisplatin is feasible, active, and well tolerated in NSCLC patients previously treated with platinum compounds, the mechanism of action remains unclear. Further study of this regimen is warranted.

Effect of acarbose on insulin sensitivity in elderly patients with diabetes.

OBJECTIVE: To study the effect of acarbose, an alpha-glucosidase inhibitor, on insulin release and insulin sensitivity in elderly patients with type 2 diabetes. RESEARCH DESIGN AND METHODS: Elderly patients with type 2 diabetes were randomly treated in a double-blind fashion with placebo (n = 23) or acarbose (n = 22) for 12 months. Before and after randomization, subjects underwent a meal tolerance test and a hyperglycemic glucose clamp study designed to measure insulin release and sensitivity. RESULTS: After 12 months of therapy there was a significant difference in the change in fasting plasma glucose levels (0.2 +/- 0.3 vs. -0.5 +/- 0.2 mmol/l, placebo vs. acarbose group, respectively; P < 0.05) and in incremental postprandial glucose values (-0.4 +/- 0.6 vs. -3.5 +/- 0.6 mmol/l, placebo vs. acarbose group, P < 0.001) between groups. There was a significant difference in the change in HbA(1c) values in response to treatment (0.4 +/- 0.2 vs. -0.4 +/- 0.1%, placebo vs. acarbose group, P < 0.01). The change in fasting insulin in response to treatment (-2 +/- 2 vs. -13 +/- 4 pmol/l, placebo vs. acarbose group, P < 0.05) and incremental postprandial insulin responses (-89 +/- 26 vs. -271 +/- 59 pmol/l, placebo vs. acarbose group, P < 0.01) was also significantly different between groups. During the hyperglycemic clamps, glucose and insulin values were similar in both groups before and after therapy However, there was a significant difference in the change in insulin sensitivity in response to treatment between the placebo and the acarbose groups (0.001 +/- 0.001 vs. 0.004 +/- 0.001 mg/kg x min(-1) [pmol/l](-1), respectively, P < 0.05) CONCLUSIONS: Acarbose increases insulin sensitivity but not insulin release in elderly patients with diabetes.

Subjectively healthy elderly consuming a liquid nutrition supplement maintained body mass index and improved some nutritional parameters and perceived well-being.

OBJECTIVE: To evaluate regular use of a liquid nutrition supplement by subjectively healthy elderly persons in terms of body mass index, nutrient intake, selected biochemical parameters, and perceived quality-of-life changes, and to identify advantages and limitations of use. DESIGN: A 16-week intervention study in which subjects were assigned randomly to either a supplemented group or a control group and compared in terms of intergroup and intragroup differences in weight, food intake, blood values, and quality-of-life indexes. Adherence to protocol was monitored by monthly visits with an interviewer and food intake records. SUBJECTS/SETTING: Seventy-one independent living, older Canadian adults (mean age = 70 +/- 7 years) consuming on average less than 4 servings of fruit and vegetables daily and a supplement-free diet before the study. Subjects were without functional limitations and did not require therapeutic diets or medical treatments that affect nutritional status. Data were collected in home interviews. Blood for analysis was obtained from a subsample of 36 subjects. INTERVENTION: Inclusion of six 235-mL cans of liquid nutrition supplement weekly into the self-selected dietary patterns of the supplemented group. STATISTICAL ANALYSIS: Results were analyzed by Student t tests or Wilcoxon rank sum test, analysis of variance, and multiple stepwise regression. RESULTS: Body mass index, energy intake, and consumption of fruit and vegetables did not change throughout the study. In the supplemented group, statistically significant increases occurred from baseline to termination of the study in these nutrients: protein, calcium, iron, magnesium, and folate. Serum albumin, folate, ferritin, hemoglobin, and zinc values were within the normal range for the supplemented and control groups. Scores for the Medical Outcomes Study 36-Item Short-Form Health Status scales increased for the supplemented group from baseline to termination for vitality and general health perception. Values for the General Well-Being Questionnaire improved for anxiety and general well-being. Of the dietary predictors, folate intake explained the most variance for vitality and for general well-being, 8.6% and 14.2%, respectively. APPLICATIONS: A liquid nutrition supplement could be recommended to the elderly when energy maintenance and increases in nutrient intake are necessary and convenience is an important consideration. Dietetics professionals should address the issues of affordability of the supplement, the role of food in achieving nutritional adequacy, and overall quality of life of clients. Folate intake as a predictor of perceived general well-being and vitality requires further investigation.

Formation and storage of 11-cis retinol in the eyes of lobster (Homarus) and crayfish (Procambarus).

Modes of storage and mechanisms of formation of 11-cis retinoids in the eyes of animals vary widely among the major phyla. We here describe evidence from two species of macruran decapod crustacea that point to different processes from those known in insects, the other group of arthropods for which there is extensive data. The eyes of the lobster (Homarus) contain about 300 pmol of retinal, somewhat less free retinol, and variable amounts (up to 1000+ pmol) of two retinyl esters, over 90% of which contain retinol in the 11-cis configuration. The major ester contains the long chain, polyunsaturated fatty acid docosahexaenoate (C22:6), but retinyl oleate (C18:1) is also present. Crayfish (Procambarus) contain the same retinyl esters, although in much smaller amounts. Homogenates of the eyes of both species are capable of isomerizing all-trans retinyl docosahexaenoate to the 11-cis configuration without using the energy of light. Crude fractionation of homogenates shows isomerase activity associated with membranes. The reaction mechanism has not been explored in detail, but on the basis of present evidence it may be similar to that found in vertebrate pigment epithelium. It is clearly different from the light-dependent processes known in insects (Hymenoptera and Diptera) and cephalopod mollusks, where isomerization takes place at the level of the aldehyde and 11-cis retinyl esters are not present as major storage reserves.

Improved hemodynamic function and mechanical efficiency in congestive heart failure with sodium dichloroacetate.

OBJECTIVES: The purpose of this study was to determine whether sodium dichloroacetate improves hemodynamic performance and mechanical efficiency in congestive heart failure. BACKGROUND: Congestive heart failure is associated with impaired hemodynamic performance and reduced mechanical efficiency. Dichloroacetate stimulates pyruvate dehydrogenase activity by inhibition of pyruvate dehydrogenase kinase, which results in inhibition of free fatty acid metabolism and stimulation of high respiratory quotient glucose and lactate consumption by the heart. Facilitation of glucose and lactate consumption with dichloroacetate should improve mechanical efficiency of the failing ventricle. METHODS: Ten patients with New York Heart Association functional class III to IV congestive heart failure were studied. Dichloroacetate (50 mg/kg body weight) was administered intravenously for 30 min, with measurements of hemodynamic variables, coronary sinus blood flow and blood gas, glucose and lactate levels for 2 h. The same patients were also given dobutamine (5 to 12.5 micrograms/kg per min) for comparison. RESULTS: Therapeutic levels of dichloroacetate were achieved (100 to 160 micrograms/liter of plasma). Myocardial consumption of lactate was stimulated from 29% to 37.4%. Forward stroke volumes increased (+5.3 ml/beat, p < 0.02), as did left ventricular stroke work (+1.8 g-m/m2 per beat, p < 0.02) and left ventricular minute work (from 1.38 to 1.55 kg-m/m2 per min, p < 0.01). Myocardial oxygen consumption decreased (from 19.3 to 16.5 ml/min, p = 0.06) as left ventricular minute work increased. Left ventricular mechanical efficiency thus improved from 15.2% to 20.6% (p = 0.03). Dobutamine administration resulted in the opposite trend with respect to myocardial lactate extraction (from 34% to 15.3%, p < 0.02). Stroke volume increased (+7.4 ml/beat, p = NS vs. dichloroacetate), as did left ventricular minute work (from 1.29 to 1.59 g-m/m2 per min, p < 0.01 vs. dichloroacetate) and myocardial oxygen consumption (from 18.6 to 21.0 ml/min, p = 0.06 vs. dichloroacetate). Left ventricular mechanical efficiency did not change with dobutamine administration (from 16.4% to 15.8%, p = NS). CONCLUSIONS: Dichloroacetate administration stimulates myocardial lactate consumption and improves left ventricular mechanical efficiency. Forward stroke volume and left ventricular minute work increase significantly, with a simultaneous reduction in myocardial oxygen consumption. Dobutamine administration results in similar hemodynamic improvements but with no change in left ventricular mechanical efficiency and with opposite effects on lactate metabolism. The opposing metabolic actions, yet similar hemodynamic responses, of dichloroacetate and dobutamine suggest that these agents may be complementary in the treatment of congestive heart failure.

Biodistribution study of Ethiodized Oil Emulsion 13 for computed tomography of the liver and spleen.

Biodistribution studies were conducted with a new intravenous lipoid contrast material currently undergoing clinical trials in four hospitals. The contrast material selectively opacifies the liver and spleen for computed tomographic examination. The experiments were performed on rats with 125I-labeled ethiodized oil emulsion. The study showed that the liver accumulates nearly 80% of the injected iodine within 15 min of the injection and retains a high concentration over 3 h. The second highest concentration was found in the spleen. More than 99% of the iodine is eliminated from the liver and spleen within 48 h, primarily through the kidneys.

Ioglucomide: a new nonionic myelographic agent. Preclinical studies.

Ioglucomide, a new iodinated nonionic contrast medium directed primarily toward myelographic use, was subjected to an extensive toxicological examination in animals. In the majority of studies, ioglucomide was compared directly with metrizamide. In some respects, including freedom from production of arachnoiditis, ioglucomide and metrizamide were comparable. However, acute toxicity after intravenous injection or instillation into cerebrospinal fluid was significantly less for ioglucomide. Also, in contrast to metrizamide, ioglucomide produced no evidence of any type of convulsive activity after subarachnoid administration. The improved safety of ioglucomide could not be related to osmolality; therefore, the importance of osmolality for nonionic myelographic agent safety is questioned.