ACTH response induced by interleukin-1 is mediated by CRF secretion stimulated by hypothalamic PGE

We investigated whether hypothalamic prostaglandin E2 (PGE2) and corticotropin releasing factor (CRF) are responsible for the development of the adrenocorticotropic hormone (ACTH) response induced by interleukin-1 alpha (IL-1 alpha). The present results show that ACTH responses induced by intravenous injection of IL-1 alpha were suppressed by systemic pretreatment with indomethacin and that intrahypothalamic injection of PGE2 stimulates the secretion of ACTH. Furthermore, systemic pretreatment with anti-CRF antibody significantly suppressed the ACTH response induced by intrahypothalamic injection of PGE2. These data suggest that the ACTH response induced by IL-1 is mediated by CRF secretion stimulated by hypothalamic PGE2.     

Reduction of bovine pulmonary hypertension by normoxia,verapamil and hexaprenaline

Summary In calves with hypoxic pulmonary hypertension, resistance was reduced by 40±3% with normoxia, 19±4% with verapamil, and 60±1% with hexoprenaline. It is possible that the increased resistance during normoxia is due partly to vasoconstriction rather than solely to vascular thickening, and that the vasoconstriction is due to an abnormality in calcium metabolism by the hypertensive vasculature.Acknowledgments. We thank Rosann Glas, Mary Munroe, Diann Smith and Linda Panepinto for technical assistance. This work was supported by the Colorado Heart Association and by the National Institutes of Health Grants HL-05973 and HL-29237. Verapamil (Isoptin) was supplied by Knoll Pharmaceutical Co. Hexoprenaline (ST 1512 HCl, Ipradol) was supplied by Österreichische Stickstoffwerke Linz.     

Intermolecular and intramolecular isotope effects in the deamination of putrescine catalyzed by diamine oxidase

Summary The enzymatic deamination of 1,4-diaminobutane (putrescine) catalyzed by hog kidney diamine oxidase was studied with the aid of deuterium labeled substrates and mass spectrometry. An intermolecular deuterium isotope effect for the deamination of putrescine labeled with deuterium in all 4 alpha positions was observed to be 1.26. 1,4-Diaminobutane-1, 1-d₂ was synthesized and intramolecular isotope effects determined. The preference of diamine oxidase for the unlabeled alpha position was about 4 times greater than for the deuterated methylene. This work shows that intramolecular deuterium isotope effects are observable in enzyme systems other than cytochrome P-450.Acknowledgment. This investigation was supported by a research grant from the National Institutes of Health, grant number NS 14017.     

Luteolytic potency of 16-phenoxy-derivatives of prostaglandin F2 alpha

The binding of 16-phenoxy derivatives of prostaglandin (PG) F2 alpha to rat luteal membranes, and also their abortifacient potency in pregnant rats, have been studied. Competitive binding studies with various PG-analogues were performed in ovaries of juvenile rats pretreated with PMSG and HCG, and in parallel studies the abortifacient potency of these substances was tested in pregnant rats. It was observed that this class of derivatives bound to the PGF2 alpha receptor as well as, or even better than the parent compound PGF2 alpha. Modifications in the carboxyl group at C-1 yielded derivatives with a higher affinity for the receptor, in decreasing order of effectiveness as follows: -COOR greater than COOH greater than OH. The data obtained from the binding studies also compared well with data on the abortifacient potency in pregnant rats. It is concluded that the addition of a phenoxy group to either the lower or upper side chain of PGF2 alpha may augment the binding to the receptor as well as the biological responses induced by the post receptor effect.     

Beta-adrenoceptor blocking drugs, heart rate and genetic hypertension development in rats.

In spontaneously hypertensive rats (SHRs) chronically treated during their growth with beta-adrenoceptor blocking drugs, no correlation was found between the reduction in heart rate and the prevention of genetic hypertension development.     

Renal vascular reactivity to ATP in hyper- and hypothyroid rats

The effects of adenosine triphosphate (ATP) on the renal vasculature of isolated kidneys from control, hyper- and hypothyroid rats were characterized. ATP responsiveness was evaluated in basal tone and in raised tone (phenylephrine 10^–6 M) preparations. These responses were compared with those obtained with barium chloride or sodium nitroprusside (SNP), used respectively as nonreceptor agonists for vasoconstriction or vasodilation. In preparations at basal tone, ATP produced dose-related vasoconstriction, which was increased in hyperthyroid kidneys, and was severely attenuated in kidneys from hypothyroid rats. In raised tone preparations from control rats ATP produced a dual response: vasoconstriction at low doses, which declined with increasing doses to give way to vasodilator responses; biphasic responses were found in some kidneys. Hyperthroid kidneys showed increased pressor responses and a vasodilator response similar to those seen in kidneys from control rats. However, in hypothyroid kidneys the vasodilator response was abolished. The responses to barium chloride and to SNP were significantly increased and decreased in hyper- and hypothyroid kidneys, respectively; vasoconstrictor responses to SNP were also found in hypothyroid kidneys. Hence the abnormal responses to ATP observed in both thyroid dysfunctions may be partially explained by unspecific alterations in the contractile machinery of the renal vasculature in these kidneys. However, ATP responsiveness (vasoconstriction at low tone and vasodilation at raised tone) was more severely affected in hypothyroid kidneys, suggesting that purinergic (P_2X and P_2Y) receptor activity may be decreased in these organs.     

A postsynaptic alpha 2-receptor: the alpha-adrenergic receptor of hamster white fat cells

The effects of selected alpha-agonists and alpha-antagonists on theophylline-induces lipolysis were investigate in isolated hamster white fat cells, alpha 2-Agonists (tramazoline, clonidine) inhibited theophylline-induced lipolysis while in alpha 1-agonist (methoxamine) was without any effect. The inhibitory effect of alpha 2-agonists was suppressed by yohimbine (alpha 2-antagonist), whereas alpha 1-antagonists were inefficient. This result implies that the alpha-adrenergic receptor of hamster fat cells is of the alpha 2-type, although postsynaptically.     

Alpha 1-adrenergic stimulation of ketogenesis and fatty acid oxidation is associated with inhibition of lipogenesis in rat hepatocytes

The effect of norepinephrine on fatty acid synthesis (3H2O incorporation into fatty acids), on fatty acid oxidation to CO2 and on ketogenesis was studied in isolated hepatocytes of fed rats. After incubation with norepinephrine (50 microM), lipogenesis was lower (5.7 +/- 1.1 nmoles 3H2O incorporated into fatty acids/mg dry weight/30 min) than in controls (7.5 +/- 1.7; n = 6, p less than 0.02). In contrast, (1-14C) palmitate conversion into total ketone bodies was increased to 10.9 +/- 1.8 nmoles/mg/30 min with norepinephrine, vs 8.5 +/- 1.6 in controls (p less than 0.05), and more (1-14C) palmitate was converted to 14CO2 with norepinephrine than in controls (1.48 +/- 0.10 nmoles/mg/30 min vs 1.06 +/- 0.11, p less than 0.05). The inhibitory effect of norepinephrine on lipogenesis was abolished by addition of the alpha 1-receptor blocker prazosin, but not by alpha 2 or beta-blockers. The results demonstrate that the ketogenic effect of norepinephrine is coupled with an inhibitory effect on lipogenesis which may be explained by diminished activity of acetyl-CoA carboxylase, diminished formation of malonyl-CoA and decreased activity of carnitine palmitoyl transferase I.     

Expansion of the bile acid pool changes the biliary transport characteristics of centrizonal hepatocytes

We investigated whether acinar differences in taurocholate transport are responsible for the increased maximal secretory rate observed after expansion of the bile acid pool. The bile acid pool was expanded by cholate feeding for four days. Periportal and centrizonal hepatocytes were then probed by ante- and retrograde liver perfusion, respectively. In control animals, secretory rate constant (alpha 1) averaged 0.439 +/- 0.123 and 0.104 +/- 0.035 min-1 during ante- and retrograde perfusion, respectively, in the absence of exogenous taurocholate. These values did not significantly change when taurocholate was infused. In cholate-fed animals, alpha 1 was comparable during antegrade perfusion but was significantly reduced (0.038 +/- 0.035, p less than 0.05) during retrograde perfusion in the absence of exogenous taurocholate, presumably owing to induction of cytosolic bile acid binding proteins. During loading with exogenous taurocholate, by contrast, alpha 1 was significantly accelerated (0.252 +/- 0.026; p less than 0.01) in centrizonal hepatocytes from bile-acid fed rats. Expansion of the bile acid pool is able to change the bile salt secretory characteristics of centrizonal hepatocytes toward those of periportal ones.     

Evaluation of monoaminergic receptors in the genetically epilepsy prone rat

The intensity of sound-induced convulsions in the genetically epilepsy-prone rat (GEPR) was reduced in a dose related fashion by intracerebroventricular administration of dobutamine, (beta 1 agonist), terbutaline (beta 2 agonist) or phenylephrine (alpha 1 agonist). BHT-920 (alpha 2 agonist) did not cause a dose-related decrease in sound-induced convulsion intensity. Binding studies showed that whole brain alpha and beta receptor densities (Bmax) were normal while the Kd was increased for the beta ligand in GEPR brain.     

Study of prostaglandin synthesis during anaphylactic shock in guinea pigs]

In guinea pigs actively sensitized with ovalbumin and shocked, we have measured blood histamine and histaminase, pulmonary content in cycli AMP and prostaglandins (PG) E1, E2 and F2alpha. In pulmonary efferent blood, both PGE and PGF are increased. In lung tissue, only PGF2alpha, which are bronchoconstructive mediators, are increased. Th increased level in PG seems to have two origins: first a specific increase, then an increased synthesis secondary to histamine release.     

Modulation of C2 and C3 gene expression of human peripheral blood monocytes by interleukin 1 beta, interferon gamma, tumor necrosis factor alpha and lipopolysaccharide.

The effect of interleukin 1 beta (IL-1 beta), interferon gamma (IFN-gamma), tumor necrosis factor alpha (TNF alpha) and lipopolysaccharide (LPS) on the expression of the C2 and C3 genes in human adherent monocytes was studied. Stimulation of monocytes with IFN-gamma increased both C2 and C3 mRNA. IL-1 beta also increased C2 mRNA level, whereas C3 gene expression was not enhanced. TNF alpha failed to increase either C2 or C3 mRNA. LPS increased C2 mRNA, but suppressed C3 gene expression. These results suggest that C2 and C3 production by monocytes is regulated by IL-1 beta and IFN-gamma in the local tissues.     

Anomaly of the polypeptide and oligosaccharide chains of alpha-2-neuraminoglycoprotein in various types of hereditary angioneurotic edema

Using two-dimensional immuno-electrophoresis to study a morphological abnormality of the alpha 2-neuramino-glycoprotein (alpha 2-NGP) we have been able to observe allelic exclusion in patients afflicted by hereditary angioneurotic oedema [1]. With the aid of two-dimensional immuno-affino-electrophoresis, we have been able to show that in some cases, there exists a double abnormality of alpha 2-NGP associating a deficiency in post translating glycosylation with a loss of the inhibitory function of the C1 esterase.     

Intermolecular and intramolecular isotope effects in the deamination of putrescine catalyzed by diamine oxidase

The enzymatic deamination of 1,4-diaminobutane (putrescine) catalyzed by hog kidney diamine oxidase was studied with the aid of deuterium labeled substrates and mass spectrometry. An intermolecular deuterium isotope effect for the deamination of putrescine labeled with deuterium in all 4 alpha positions was observed to be 1.26. 1,4-Diaminobutane-1,1-d2 was synthesized and intramolecular isotope effects determined. The preference of diamine oxidase for the unlabeled alpha position was about 4 times greater than for the deuterated methylene. This work shows that intramolecular deuterium isotope effects are observable in enzyme systems other than cytochrome P-450.     

Laminins during muscle development and in muscular dystrophies

Cellular interactions with the extracellular matrix during muscle formation and in muscular dystrophy have received increased interest during the past years. Laminins constitute a growing family of proteins with complex expression patterns in forming basement membranes during muscle development. In skeletal muscle, laminins constitute major ligands for cell surface receptors involved in the transmission of force from the cell interior, but laminins might also influence signal transmission events during muscle formation and in muscle regeneration. During myogenesis the laminin alpha1 chain is present around the epithelial somite; but later, in forming muscle, the laminin alpha1 chain is restricted to the myotendinous junction. The laminin alpha2, alpha4 and alpha5 chains are major laminin chains in the muscle basement membrane during muscle formation, but laminin alpha4 and alpha5 chains are absent in adult muscle. The importance of laminins for muscle integrity is manifested in congenital muscular dystrophies with defects in the laminin alpha2 chain. There is no good evidence for the presence of laminin alpha1 chain in dystrophic muscle, but some other fetal muscle laminins can be detected in dystrophic muscle. Characterization of laminin expression patterns in muscular dystrophies might be of diagnostic and therapeutic value. In this paper, we review the recent publications on the biological functions of muscle laminins and discuss their roles in skeletal muscle.     

Age-related differences in the urinary excretion of prostaglandin F2 alpha catabolites in the rat

Tritium-labeled PGF2 alpha was administered i.v. into rats of varying ages (2, 4, 6 weeks and adult). Urine was collected and assayed for radioactive products by thin-layer-chromatography. Results showed a distinctly different urinary profile between the 2-week-old and the adult rat. While the urinary pattern from the 2-week-old rat gave a single less polar product than PGF2 alpha, the pattern from the adult rat gave products more polar than PGF2 alpha. Urine from the 4- and 6-week-old rats gave a mixture of these types of products. These results indicate that some prostaglandin catabolic pathway (likely the omega-oxidative system) is activated in vivo within the 4-6 week postnatal period in the rat.     

TGFβ-induced protein mediates lymphatic endothelial cell adhesion to the extracellular matrix under low oxygen conditions

TGFbeta-induced protein (TGFBI) is an extracellular protein that mediates cell adhesion to collagen, laminin and fibronectin through its interaction with different beta integrins. We had previously reported that hypoxia-induced TGFBI mRNA expression in lymphatic endothelial cells (LEC). Here, we demonstrate that TGFBI can contribute to hypoxia-induced increases in LEC adhesion to the ECM. We show that while there are no changes in alpha1, alpha4, alphav, beta1, beta2, beta3, alpha5beta1, alphavbeta3, alphavbeta5 integrin expression on the LEC surface after hypoxia exposure, there exists an accumulation of TGFBI adaptor protein in LEC supernatants. We also demonstrate that hypoxia driven TGBFI expression is dependent on TGFbeta production by LEC. Furthermore, we show that TGFBI mediated LEC adhesion and migration through the ECM by its binding to the beta3 integrin. The identification of the specific mechanisms regulating LEC-ECM interactions may help us design new therapeutic applications for diseases in which lymphatic vessel function is compromised.     

Effects of injury on the concentration of alpha1-macroglobulin and alpha2-macroglobulin in the plasmas of male and remale rats.

The effects of injury on the concentration of alpha1-macroglobulin and alpha2-macroglobulin in the plasmas of male and remale rats has been investigates. At 5 days after injury to the male rats the alpha1-macroglobulin concentration increased to 131% of its preinjury value. The alpha2-macroglobulin concentration increased more rapidly to a maximum of 86 times its initial value. In the female rats alpha2-macroglobulin increased only slightly and alpha1-macroglobulin not at all.