Research communications in chemical pathology and pharmacology最新文献

The antinociceptive effect of (+/-)pentazocine was examined in streptozotocin-induced diabetic mice. Although intracerebroventricular (i.c.v.) administration of (+/-)pentazocine (10 nmol) produced a significant antinociceptive effect in both non-diabetic and diabetic mice, the antinociceptive effect of (+/-)pentazocine was greater in diabetic mice than in non-diabetic mice. The antinociceptive effects of (+/-)pentazocine in both diabetic and non-diabetic mice were significantly antagonized by s.c. administration of nor-binaltorphimine, a selective kappa-opioid receptor antagonist. On the other hand, the antinociceptive effects of (+/-)pentazocine were potentiated when non-diabetic mice were pretreated with beta-funaltrexamine, a selective mu-opioid receptor antagonist. Furthermore, there was no significant difference in the antinociceptive effect of (+/-)pentazocine between diabetic mice and beta-funaltrexamine-treated non-diabetic mice. These results suggest that the hypo-responsiveness of mu-opioid receptors may account for the enhanced kappa-opioid receptor-mediated antinociceptive effect of (+/-)pentazocine in diabetic mice.

Serum and urinary neopterin levels and serum 2',5'-oligoadenylate synthetase and DNA polymerase activities were measured in 14 patients with HBeAg-positive chronic hepatitis B treated with interferon. Treatment with interferon brought about a threefold increase over basal levels in serum and urinary neopterin levels one week after the start of treatment. Both neopterin levels remained significantly elevated during treatment but rapidly returned to basal levels after the completion of treatment. Serum and urinary neopterin levels changed with a pattern similar to that of serum 2',5'-oligoadenylate synthetase activity and with a mirror image to serum DNA polymerase activity. It is indicated that measurement of serum and urinary neopterin can be used as a marker for cell-mediated immunity during interferon therapy for chronic hepatitis B, but can not be used to predict the short-term clinical effects of interferon treatment as in the case of serum 2',5'-oligoadenylate synthetase.

The effect of somatomedin C on the hepatic drug-metabolizing enzyme system in rat liver after sc injection, a clinically applicable dosing route, was studied. Although liver weight was slightly increased after somatomedin C (1 mg/kg) was injected for 7 days, no significant changes were observed in other dosing group (0.1 and 10 mg/kg). There were no significant effects of somatomedin C on cytochrome P-450 and b5 contents, and NADPH-cytochrome c reductase, aminopyrine demethylase, aniline hydroxylase, and ethoxyresorufin deethylase. Additionally, somatomedin C treatment did not affect the activities of 2 alpha-, 2 beta-, 6 beta- and 16 alpha-hydroxytestosterone and androstenedione formation from testosterone. Changes relation to dosing period were also examined with 1 mg/kg of somatomedin C. In this case, hepatic levels of cytochrome P-450 and b5, NADPH-cytochrome c reductase and drug oxidations did not differ significantly among groups treated for 3, 7, or 14 days. These results suggest that somatomedin C has no effect on the hepatic mixed-function oxidase system.

To examine the roles of thromboxane A2 and prostaglandin I2, which are arachidonic acid metabolites found in patients with sepsis, we measured the serum levels of their respective stable metabolites, thromboxane B2 (TXB2) and 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) in 22 patients with sepsis. Results were analyzed in relation to patients' survival. The levels of both TXB2 and 6-keto-PGF1 alpha were significantly higher in patients who died than in those who survived, thus reflecting the severity of the patients' illness. There was a significant correlation between the levels of TXB2 and 6-keto-PGF1 alpha. These findings suggest that TXA2 and PGI2 are chemical mediators involved in the severity of clinical sepsis.

Nitric oxide (NO) is made by NO synthase during the conversion of arginine to citrulline. Researchers have found that they can block the actions of excitotoxins by inhibiting NO synthase. Released from excitable cells during trauma, NO may react with superoxide to form peroxynitrite. Once formed, peroxynitrite and its products can then react with proteins, lipids and nucleic acids resulting in cell injury and death. The present study was undertaken to investigate analogs of cysteine as scavengers of peroxynitrite. Peroxynitrite scavengers were assayed by Attoflo, an automated radioimmunoassay. Briefly, peroxynitrite, in a dose-dependent manner (0.1 to 10 mM), inhibited the binding of I125 cAMP to a polyclonal antibody used in the assay of cAMP. Drugs were tested for blockade of the inhibition (90%) caused by peroxynitrite at 10 mM. Cysteine blocked the inhibition of ligand/antibody binding in a dose-dependent manner (EC50 = 3 mM). Cysteine, cysteine esters, penicillamine, penicillamine esters and cysteamine were the most effective peroxynitrite scavengers. Analogs of cysteine may thereby protect cells from nitric oxide toxicity.

Contractile responses to norepinephrine (noradrenaline, NE 10(-5) M) in the canine saphenous vein (SV) are significantly, although slightly, reduced (14%) when induced in a physiological medium depleted of calcium for 1 hour (+ EGTA). In contrast, they are inhibited by about 75% after 24 hr in calcium free physiological saline solution (P.S.S.). ED50 of norepinephrine in 1-hr calcium-free medium and in normal Ca++ P.S.S. are 6 x 10(-7)M and 4.2 x 10(-7)M, respectively. Two blockers of extracellular calcium entry have also been cited as inhibitors of intracellular calcium pool refilling. At concentrations of 10(-6)M, 10(-5)M and 10(-4)M, diltiazem and nicardipine inhibit the norepinephrine-induced contractions (NIC) in a concentration-dependent manner. At 10(-4)M, the two calcium blockers inhibit the NIC by 70% and by 72% respectively in Ca++ free (+ EGTA) P.S.S. Nifedipine and verapamil only begin to significantly inhibit NIC in Ca++ free (+ EGTA) P.S.S. at concentrations equal to or greater than 10(-5)M. At 10(-4)M concentration, control inhibition in Ca++ free P.S.S. was observed as 60% and 49%, respectively. Contrary to the other 3 calcium antagonists tested, diltiazem antagonises NIC significantly less in calcium-containing medium (45%) than in calcium-free medium (72%). Procaine at a concentration of 10(-3)M, described as sufficient to totally inhibit calcium release from its intracellular storage sites, only inhibits NIC by 52% in calcium free (+ EGTA) P.S.S. These results are consistent with the following conclusion: i) in the canine saphenous vein (SV), NIC is mainly mediated by calcium mobilization from its intracellular storage sites; ii) the calcium antagonists tested here and procaine are unable to totally inhibit, even at high concentrations, the contractions induced via intracellular calcium release; this characteristic is nonsignificant for nifedipine and verapamil at low concentrations (10(-6)M). iii) verapamil and nifedipine, like diltiazem and nicardipine at high concentrations, may not only possess the characteristics of extracellular calcium entry blockers, but also that of partial antagonist of NIC via non specific mechanisms; iv) diltiazem may relax the vascular smooth muscle of SV, not only by the above two properties, but also through another mechanism yet unknown; v) partial persistence of NIC on the SV under conditions of short or long extracellular calcium depletion may be due to a mechanism of intracellular Ca++ recycling, the smooth muscle cell partially retaining its intracellular Ca++.

Fischer 344 rats were fed a low-fat high carbohydrate (HC) diet, an isocaloric fat-containing (IC) diet, a hypercaloric fat-containing (HF) diet or a commercial rodent chow. The effects of these diets were studied on the binding of aflatoxin B (AFB1) to exogenous DNA, and on the activities of hepatic glutathione transferases (GSTs), cytochromes 2B1 and 1A1. Microsome-mediated binding of [3H]AFB1 to exogenous DNA was significantly lower in the HC-rats than in the chow and IC-fed rats. No significant differences were noted between HF and either HC or IC rats. There was no significant difference in hepatic GST activity of rats fed the different diets. Our results suggest that high-carbohydrate low-fat diets reduce microsome mediated epoxidation of AFB1 to a larger extent than high-fat diets. In general, high fat diets increased cytochrome 1A1 and 2B1 activities relative to chow and high carbohydrate diet. This suggests greater detoxification of AFB1, thus reducing the amount of AFB1 available for hepatic macromolecular binding.

Liver slices from Wistar and Long-Evans Cinnamon (LEC) rats were incubated while open to the atmosphere to assess the liver function in LEC rats. Leakages of glutamic-oxaloacetic transaminase (GOT) and lactic dehydrogenase (LDH) into the medium were significantly lower in the LEC rat than in the Wistar rat. Furthermore, no pronounced enhancement of the concentration of thiobarbituric acid-reactive substances (TBARS) was found in the LEC rat. Hepatic Cu and Cu-metallothionein (Cu-MT) concentrations were 355.0 +/- 18.7 micrograms/g liver and 2559 +/- 181 micrograms/g protein in the LEC rats, whereas Wistar rats showed 4.1 +/- 0.1 Cu microgram/g liver accompanied by 16 +/- 4 micrograms/g protein of MT. The decrease of intrahepatic Cu-MT in LEC rats was stimulated by incubation with Fenitrilotriacetate (Fe-NTA). There was a direct correlation between the enhancement of TBARS and disappearance of Cu-MT. Our results suggest that hepatic Cu-MT in LEC rats protects against liver injury stimulated by oxidative stress.

Platelet activating factor acetylhydrolase (PAF-AH) activity was measured in patients with sepsis, and its relationships with various cytokines and endotoxin were evaluated. PAF-AH activity was significantly higher (p = 0.0136) in 17 patients who died than 13 patients who survived. PAF-AH activity showed significant correlations with the plasma endotoxin, TNF-alpha, and IL-8 levels. These findings suggest that PAF-AH activity reflects the severity of the pathological condition.

It was reported that cell-sheets composed of rat liver cells could be obtained by using a collagen-conjugated thermo-responsive polymer, poly-N-isopropyl acrylamide, as a cell substratum and they were then able to transform into multicellular spheroids in the hydrophobic dish. In this study, we succeeded in easily obtaining the cell-sheets with the intended size by using the etched substratum. Biochemical analyses of spheroids derived from cell-sheets with areas of 0.2, 0.5 and 2.5 cm2 were carried out. Each cell-sheet rapidly aggregated at the same rate and finally turned into a multicellular spheroid within 5 days after the detachment. However, both decreases of DNA and LDH contents in cell-sheets with an area of 2.5 cm2 within 24 hr after the detachment were more obvious than in the others, respectively. It is tempting to speculate from these data that the vital spheroids with the desired size can be easily obtained by using our new method.