E2-like Activity Research Articles

Effects of nitric oxide donor and inhibitor on prostaglandin E2-like activity, malondialdehyde and reduced glutathione levels after skeletal muscle ischemia-reperfusion

Oxygen free radicals are implicated in the pathophysiology of ischemia-reperfusion (I/R) injury in skeletal muscle. Nitric oxide (NO) and prostaglandin E2 (PGE2) are important regulators of the microcirculation in skeletal muscle. The effects of L-arginine, substrate for NO, and NG-nitro L-arginine methyl ester (L-NAME) on PGE2 synthesis, lipid peroxidation and reduced glutathione (GSH) levels was investigated in the rat gastrocnemius muscle after 3 h of reperfusion following 2 h of ischemia.Lipid peroxidation and GSH levels showed a non-significant changes in the I/R groups compared to the control group. According to these results, it can be assumed that skeletal muscle can resist 2 h of ischemia followed by 3 h of reperfusion-induced oxidative stress.PGE2-like activity in the gastrocnemius muscle increased in the L-NAME treated and I/R groups. L-arginine administration reversed the increase in PGE2-like activity of reperfused skeletal muscle. These findings support the conclusion that endothelium-derived PGE2 synthesis increases during reperfusion and suggest that PGE2 may have a protective role in the maintenance of endothelial function.

The effect of granulocyte macrophage-colony stimulating factor on the prostaglandin E2-like activity of the small intestine of rat during total body irradiation

Radiation-induced gastrointestinal toxicity is important for subjects receiving radiation to the pelvis. Eicosanoids and free radicals may be involved in the mechanism. rHuGM-CSF is a subcutaneously administered drug which may reduce some side effects of radiation. This experimental study was undertaken to determine the effectiveness of rHuGM-CSF on PGE2-like activity of the small intestine in rats. Thirty-two adult male Wistar-Albino rats entered the study to be randomized to one of the four groups: Group I. Control; II. Drug administered; III. Irradiated; IV. Irradiated and drug administered. Radiation was by total body irradiation, 800 rads with Cobalt 60. On the 9th day the animals were killed and biopsies were taken from the terminal ileum. PGE2-like activity was evaluated. Animals were weighed on the day of irradiation and end of the experiment. A statistically significant difference was found according to pre- and post-treatment weights in the irradiated and nonirradiated drug administered groups (Groups II and IV) (P=0.035 and 0.018, respectively). PGE2-like activity in the intestinal tissue was statistically significant higher in the drug-treated animals, both in non-irradiated and irradiated groups. Surprisingly, irradiation was found to decrease the PGE2-like activity in the intestinal tissue (P=0.008). rHuGM-CSF was found to increase PGE2-like activity in the intestinal tissue. The cellular mechanisms underlying this must be clearly determined and weighed carefully in considering the drug for clinical usage.

Anti-idiotypic antibody as an oestrogen mimetic: removal of Fc fragment converts agonist to antagonist

Previous studies indicated that the anti-idiotypic antibody (clone 1D5) caused an increase in uterine creatine kinase (CK) activity when administered in vivo to immature female rats, indicating that the antibody has oestrogenic-like activity. It was, therefore, of interest to investigate the structural requirements of clone 1D5 to act as an oestrogen mimetic in an in vitro model system. In the present study, the effect of clone 1D5 and its proteolytic fragments, F(ab')2, Fab' and Fc on CK activity was examined in cultured skeletal cells having functional oestrogen receptor (ER). Incubation of female-derived calvaria cells or epiphyseal cartilage cells with clone 1D5 (8.33 nM) or oestradiol (E2) (30 nM) for 24 h caused a significant increase in CK activity, indicating that clone 1D5 acted as an agonist. On the other hand, incubation of male-derived calvaria cells devoid of a functional ER with clone 1D5 or E2 did not have any effect on CK activity. Incubation of female-derived calvaria cells with clone 1D5 and E2 did not result in any further increase in CK activity, whereas dihydrotestosterone (DHT) did not alter the response to clone 1D5. The CK response to clone 1D5, in female-derived calvaria cells was time- and dose-dependent and could be inhibited in a dose-dependent manner by the oestrogen antagonist tamoxifen. In contrast, the proteolytic fragments of clone 1D5, the F(ab')2 dimer (12 nM) and the Fab' monomer (24 nM), and the Fc fragment (28 nM) did not have E2-like activity in these cells.(ABSTRACT TRUNCATED AT 250 WORDS)

EFFECT OF PREOPERATIVE I. M. ADMINISTRATION OF DICLOFENAC ON SUXAMETHONIUM-INDUCED MYALGIA

We have studied the effects of preoperative administration of diclofenac on suxamethonium-induced myalgia, plasma met-enkephalin-like activity (E-LA), prostaglandin E2-like activity (PGE2-LA), leukotriene C4-like activity (LTC4-LA) and histamine-like activity (H-LA). Thirty-four ASA I patients undergoing elective ophthalmic surgery were allocated randomly to two groups to receive either saline placebo or diclofenac 75 mg i.m. 20 min before operation, in a double-blind design. Anaesthesia was induced with thiopentone 5-7 mg kg-1 followed by suxamethonium 1.5 mg kg-1 and maintained with 67% nitrous oxide and halothane in oxygen. Plasma PGE2-LA, LTC4-LA, H-LA and E-LA were measured before premedication, 1 min after the administration of suxamethonium and 24 h after operation. Muscle fasciculations, intubation conditions and postoperative myalgia were graded numerically. Postoperative myalgia in the diclofenac group was significantly (P < 0.05) less (47.1%) than in the control group (76.5%). Post-suxamethonium and 24-h concentrations of plasma PGE2-LA and LTC4-LA were also significantly (P < 0.05) greater than baseline in the control group. Plasma H-LA was increased in both groups after suxamethonium and this increase was significant (P < 0.05) in the control group. We conclude that diclofenac reduces significantly the incidence and intensity of suxamethonium-induced myalgia.

Transcriptional trans-activation by the human papillomavirus type 16 E2 gene product

We identified a conditional transcriptional enhancer in the long control region (LCR) of human papillomavirus type 16 (HPV-16). This conditional enhancer requires activation in trans by a product of the viral early-region open reading frames (ORFs). Primer extension analysis of chloramphenicol acetyltransferase RNA isolated from transiently transfected CV-1 cells demonstrated that trans-activation of the HPV-16 LCR enhancer operated at the transcriptional level. Mutational analysis of the early ORFs demonstrated that the conditional enhancer of the LCR was trans-activated by the product of the E2 ORF. The E2 gene product of bovine papillomavirus type 1, which can trans-activate the conditional enhancer in the bovine papillomavirus type 1 LCR, was also capable of trans-activating the E2-responsive enhancer of HPV-16. The activity of the HPV-16 LCR enhancer was also assayed in two human cervical carcinoma cell lines, HeLa and SiHa, which harbor transcriptionally active, integrated HPV-18 and HPV-16 DNA sequences, respectively. No endogenous E2 or E2-like activity was detected in either cell line.

Flunixin inhibits prostaglandin E2 production in equine inflammation

A model of acute inflammation was used in a cross-over study in Welsh mountain ponies to assess the actions of flunixin meglumine on selected components of a localised inflammatory reaction induced by injecting 0.5 ml of a 2 per cent carrageenin solution into subcutaneously implanted tissue cages. Samples of exudate were harvested at predetermined times between three and 48 hours. Increases in leucocyte numbers and protein concentration were not prevented by flunixin treatment. Prostaglandin E2-like activity was present in exudates from untreated ponies with the highest mean concentration occurring at 12 hours. The production of prostaglandin E2-like activity by the inflamed tissues of treated animals was blocked by flunixin for at least 24 hours.

Cellular and humoral components of bronchoalveolar lavage in the sheep.

Fiberoptic bronchoscopy was used as a simple and well tolerated technique for segmental bronchoalveolar lavage and cytologic study in unsedated, unanesthetized sheep. In 20 healthy animals, repeated results of analyses (three times every two weeks) of selected humoral and cellular components of lung defense mechanisms are described. Yields of 1×107 free airway cells (FAC) per lavage were easily obtained with greater than 70% cells being macrophages and 10–15% lymphocytes. Phagocytosis by FAC was readily studied provided the animal basal temperature of 39° C was used during cell incubation. DNA synthetic activity of FAC was measured by mitogen stimulation assays and the effect of asbestos on this activity was evaluated. Prostaglandin synthesis and phospholipase A activity in FAC were assessed in similar circumstances. Total proteins, albumin and prostaglandin E2-like activity was also measured in the bronchoalveolar lavage (BAL) supernatant. No significant changes were seen after repeated bimonthly lavages. The conscious sheep offers an excellent model for studying pulmonary functions, for obtaining transbronchial biopsies and for bronchoalveolar lavage. Although the model was developed for future studies on lung defense mechanisms, this paper describes cellular and humoral data obtained in normal sheep.

Effect of topical and intraperitoneal indomethacin on the generation of PGE 2-like activity in rabbit conjunctiva and iris-ciliary body

A significant difference was observed in the generation of prostaglandin (PG)E2-like activity between rabbit iris-ciliary body and conjunctiva. The amount of PGE2-like activity produced at any given concentration of arachidonic acid (AA) by the iris-ciliary body was 2–3 times greater than the amount synthesized by the conjunctiva under identical experimental conditions. Also, synthesis of PGE2-like activity was dose-dependent in the iris-ciliary body in the concentration range of 1, 5 and 10 μg AA while in the conjunctiva it was dose-dependent in the concentration range of 10, 50 and 100 μg AA. The effect of indomethacin (INDO) in vivo on the generation of PGE2-like activity in the rabbit conjuctiva and iris-ciliary body was also assessed. Topical INDO (50μl), in concentrations of 0·1%, 0·25% and 0·5%, inhibited the generation of PGE2-like activity from AA in iris-ciliary body and conjunctiva at 2 hr after instillation, respectively. Similarly, intraperitoneal (i.p.) INDO treatment (5 mg/kg, 50mg/kg and 100 mg/kg) inhibited the generation of PGE2-like activity produced from various concentrations of AA in the iris-ciliary body and conjunctiva. However, again a significant difference was observed in the susceptibility of the production of PGE2-like activity to inhibition by INDO between the iris-ciliary body and conjunctiva especially when these tissues were incubated with higher concentrations (>10 μg) of AA. Under these conditions, INDO was less effective in inhibiting PGE2-like activity production in the iris-ciliary body than in the conjunctiva. These results indicate that the substrate concentration is a limiting factor in assessing the inhibitory effects of INDO. However, differences between the distribution of INDO into the anterior uvea and conjunctiva following i.p. or topical pretreatment cannot be excluded. The significance of these findings is discussed.

Venous prostaglandin-like activity in diarrhoeal states.

Prostaglandin E2-like activity was determined in peripheral venous blood of control subjects and in patients with acute gastroenteritis and active ulcerative colitis, using a bioassay method. No significant diurnal variations of prostaglandin levels were detected in the control group, while significantly raised venous plasma prostaglandin-like activity was detected in acute gastroenteritis and in active ulcerative colitis.

Prostaglandin production by macrophages and the effect of anti-inflammatory drugs.

1 Macrophages derived from peritoneal cavity inflammatory exudates of guinea-pigs produced substantial amounts of prostaglandin E2-like activity during in vitro culture, so providing the basis for an experimental model of prostaglandin production during inflammatory reactions. 2 Dose-related inhibition of prostaglandin biosynthesis was demonstrated by 16 acidic non-steroidal anti-inflammatory drugs. 3 Seven anti-inflammatory glucocorticosteroid preparations inhibited prostaglandin production in a dose-related manner. The relative potencies of dexamethasone, prednisolone and hydrocortisone were consistent with clinical anti-inflammatory ranking. Cortisone, however, failed to inhibit macrophage prostaglandin production. 4 Three other agents used in the treatment of inflammatory joint diseases were examined. Sodium aurothiomalate inhibited prostaglandin production, although higher concentrations were toxic to macrophages. D-Penicillamine did not affect macrophage prostaglandin production. Colchicine, in contrast, enhanced prostaglandin production at some concentrations. 5 The probable significance of macrophages as a source of prostaglandins, during inflammatory responses, is discussed.

Prostaglandin production by experimental tumours and effects of anti-inflammatory compounds.

THE presence of small quantities of prostaglandin-like material has been demonstrated in medullary carcinoma of the thyroid1 and in Kaposi's sarcoma2; the diarrhoea often associated with these tumours has been attributed to prostaglandins. Diarrhoea is also often present in mice bearing the BP8/P1 tumour. Preliminary investigations of the ascitic fluid from mice inoculated with this tumour showed the presence of pharmacologically active substances and prostaglandin E2-like activity was found in small amounts3. Subsequent examination of the BP8/P1 cells has revealed concentrations of prostaglandin E2 in excess of 100 times that of the fluid. Significant amounts have also been found in another tumour, sarcoma 180 (S180).