Indomethacin potentiates the vasoconstrictor actions of angiotensin II in normal man

The blood pressure response to graded infusions of angiotensin II was assessed under control conditions and following short term (16 hour) indomethacin treatment utilizing normal men equilibrated on a constant diet of normal sodium and potassium content. Although basal mean blood pressure was unchanged, the increase in blood pressure with all rates of angiotensin II infusion ranging from 200 to 1000 ng/min was significantly greater with indomethacin treatment. Pre-infusion body weight and plasma renin activity were similar under the two conditions. These results suggest that prostaglandins modulate the systemic vasoconstrictor effects of angiotensin II.     

C4b binding protein binds to CD154 preventing CD40 mediated cholangiocyte apoptosis: a novel link between complement and epithelial cell survival

Activation of CD40 on hepatocytes and cholangiocytes is critical for amplifying Fas-mediated apoptosis in the human liver. C4b-Binding Protein (C4BP) has been reported to act as a potential surrogate ligand for CD40, suggesting that it could be involved in modulating liver epithelial cell survival. Using surface plasmon resonance (BiaCore) analysis supported by gel filtration we have shown that C4BP does not bind CD40, but it forms stable high molecular weight complexes with soluble CD40 ligand (sCD154). These C4BP/sCD154 complexes bound efficiently to immobilised CD40, but when applied to cholangiocytes they failed to induce apoptosis or proliferation or to activate NFkB, AP-1 or STAT 3, which are activated by sCD154 alone. Thus C4BP can modulate CD40/sCD154 interactions by presenting a high molecular weight multimeric sCD154/C4BP complex that suppresses critical intracellular signalling pathways, permitting cell survival without inducing proliferation. Immunohistochemistry demonstrated co-localisation and enhanced expression of C4BP and CD40 in human liver cancers. These findings suggest a novel pathway whereby components of the complement system and TNF ligands and receptors might be involved in modulating epithelial cell survival in chronic inflammation and malignant disease.     

Beta-adrenergic binding is increased by melatonin and alpha-adrenergic compounds

Binding of the beta-adrenergic ligands [3H]dihydroalprenolol and [125I]cyanopindolol to pineal particulate fractions was increased 1- to 3.5-fold by addition of low concentrations of melatonin, alpha-adrenergic agonists, or alpha-adrenergic antagonists. Minimum concentrations of melatonin or alpha-adrenergic compounds which increased beta-adrenergic binding were between 1 pM and 0.1 nM. The increased binding of [3H]dihydroalprenolol caused by melatonin (0.1 muM) was attributed to a major increase in Bmax, which persisted in protein fractions after removal of melatonin. Melatonin enhancement of [3H]dihydroalprenolol binding was apparent after 5 to 7 min (30(0], was was optimal between 20 and 40 min, and decreased at longer times. Alpha-Adrenergic receptors are unchanged during beta-receptor enhancement.     

In Vivo Characterization of (−)(−)MCL-144 and (+)(−)MCL-193: Isomeric,Bivalent Ligands with Mu/Kappa Agonist Properties

Once opioid receptor dimers were postulated, a goal has been to synthesize and screen novel opioids, with the hope of furthering our knowledge of the structure-activity relationship of opioid ligands with the opioid receptors. The aim of the current study was to address whether two isomeric bivalent ligands would have pharmacological differences after central administration, in vivo. The two compounds, (−) bis(N-cyclobutylmethyl-morphinan-3-yl) sebacoylate dihydrochloride (MCL-144) and 1−((+)N-cyclobutylmethylmorphinan-3-yl)-10-((−) N-cyclobutylmethylmorphinan-3-yl)sebacolyate (MCL-193) are each linked by a 10-carbon chain ester. The active (−) enantiomer for both ligands is 3-hydroxy-N-cyclobutylmethyl morphinan ((−)MCL-101), a N-cyclobutylmethyl analogue of cyclorphan (J Med Chem 43:114–122, 2000). MCL-144 contains two active levo rotatory (−)(−) pharmacophores, while MCL-193 contains one active (−) and one inactive (+) pharmacophore of MCL-101. In vitro analysis demonstrated that all three compounds, (−)(−)MCL-144, (+)(−)MCL-193 and (−)MCL-101 were κ agonists and μ partial agonists. (−)(−)MCL-144 and (−)MCL-101 had much higher affinity for both the μ and κ opioid receptors compared to (+)(−)MCL-193. In vivo, (−)(−)MCL-144 and (+)(−)MCL-193 produced full dose–response curves, in the 55°C tail-flick test, with each compound having an ED₅₀ value of 3.0 nmol after intracerebroventricular (i.c.v.) administration. The analgesic properties of both compounds were antagonized by the μ-selective antagonist, β-funaltrexamine and the κ-selective antagonist nor-binaltorphimine. Concomitant, i.c.v., administration of either (−)(−)MCL-144 or (+)(−)MCL-193 with morphine, did not significantly antagonize morphine-induced antinociception at any dose tested. In antinociceptive tests, (−)(−)MCL-144 and (+)(−)MCL-193 had the same pharmacological properties, demonstrating that having two active pharmacophores separated by a 10-carbon spacer group did not increase the antinociceptive efficacy of the compound. Additionally, it was also of interest to compare (−)(−)MCL-145 and (−)(−)MCL-144, as the only difference between these bivalent ligands is the spacer region connecting the two pharmacophores, yet (−)(−)MCL-145 produced an ED₅₀ value 10-fold lower than (−)(−)MCL-144 (ED₅₀ values = 0.3 nmol and 3.0 nmol, respectively). Special issue article in honor of Dr. Ji-Sheng Han.     

Transfection of lung cells in vitro and in vivo: effect of antioxidants and intraliposomal bFGF

We hypothesized that constitutive formation of reactive oxygen species by respiratory cells is a barrier to gene transfer when liposome-DNA complexes are used, by contributing to rapid degradation of plasmid DNA. When plasmid DNA is complexed to liposomes it is protected against H(2)O(2)-mediated degradation but not that mediated by the hydroxyl radical. Treatment of distal rat fetal lung epithelial cells (RFL(19)Ep) with the vitamin E analog Trolox (50 microM) reduced intracellular plasmid degradation. Both Trolox (50 microM) and an iron chelator, phenanthroline (0.1 microM), significantly increased transgene expression in RFL(19)Ep approximately twofold, consistent with a hydroxyl radical-mediated inhibition of transgene expression. When basic fibroblast growth factor (bFGF; 20 ng/ml), a growth factor with antioxidant properties, was included within liposomes, we observed a significantly greater enhancement of RFL(19)Ep transgene expression (approximately 2-fold) over that seen with Trolox or phenanthroline. Inclusion of bFGF within liposomes also significantly enhanced (approximately 4-fold) transgene expression in mice following intratracheal instillation.     

The influence of submerged pulpwood on feeding and condition of fishes in a reservoir

One hundred and forty years of log driving in the Kennebec River, Maine, left an estimated one to two million cords of submerged pulpwood logs, with major accumulations in reservoirs such as Wyman lake. Commercial salvaging of these logs began in 1978, which prompted a study to assess the importance of these logs to fishes and the potential effects of log salvaging. Vertical gill nets were set in Wyman Lake, in areas with and without logs, to measure fish densities and to obtain specimens for analysis of food habits and body conditions. Yellow perch (Perca flavescens) were more abundant in sites without logs (P < .05), but suckers (Catostomus spp.) were more abundant in sites with logs (P < 0.05). Yellow perch preyed primarily on cladocerans in sites without logs and on larger invertebrates in sites with logs, implying a difference in prey availability between study sites. Although the yellow perch and common shiners captured in non-log areas were longer than those in log areas (P < 0.05), their body conditions were not significantly different. Moderate log salvage operations would probably have little effect on the body conditions and abundances of fishes in Wyman Lake, if precautions were taken to avoid disruption of spawning and nursery areas at critical times of the year; impacts would vary in other lakes with differing topography and species compositions.