Major proteins of bovine seminal plasma and high-density lipoprotein induce cholesterol efflux from epididymal sperm.

One of the hypotheses to explain the mechanism of capacitation involves the loss of sperm membrane cholesterol. Here, we studied whether or not the major proteins of bovine seminal plasma designated as BSP-A1, -A2, -A3, and -30-kDa (collectively called BSP proteins), which are implicated in sperm capacitation, induce cholesterol efflux. When epididymal sperm were labeled with [3H]cholesterol and incubated with bovine seminal plasma (0.

Effects of protein kinase C modulators on Na+/K+ adenosine triphosphatase activity and phosphorylation in aortae from rats with cirrhosis.

Protein kinase C (PKC) modulates the activity and phosphorylation of the catalytic alpha-subunit of sodium-potassium-adenosine triphosphatase (Na+/K+ ATPase) in normal arteries. Because PKC is altered in cirrhotic aortae, Na+/K+ ATPase may also be altered in these arteries. The aim of the present study was to investigate alpha-subunit activity and phosphorylation in aortae from normal and cirrhotic rats, under baseline conditions and during exposure to PKC modulators.

Beneficial hemodynamic effects of bosentan, a mixed ET(A) and ET(B) receptor antagonist, in portal hypertensive rats.

In patients with cirrhosis, the plasma level of endothelin, a potent vasoconstrictor peptide, is elevated, and endothelin plays a role in increased intrahepatic vascular resistance. Thus, the aim of this study was to evaluate the hemodynamic effects of bosentan, a mixed ET(A) and ET(B) endothelin receptor antagonist in three models of portal hypertension. In all groups of rats, endothelin (2 microg/kg intravenously) administration significantly increased intrahepatic vascular resistance.

Body pool and synthesis of ascorbic acid in adult sea lamprey (Petromyzon marinus): an agnathan fish with gulonolactone oxidase activity.

Although many vertebrates can synthesize ascorbic acid (vitamin C), it is still unclear from the evolutionary perspective when the ability to synthesize the vitamin first appeared in the animal kingdom and how frequently the trait has been lost. We report here ascorbic acid biosynthesis ability in sea lamprey (Petromyzon marinus) which represent the most ancient vertebrate lineage examined thus far for presence of gulonolactone oxidase, the enzyme catalyzing the terminal step in biosynthesis of vitamin C. This finding supports the view that the ancestors of living vertebrates were not scurvy prone and that the loss of gulonolactone oxidase activity subsequently occurred several times in vertebrate phylogeny.

Influence of aluminum on the regulation of PTH- and 1,25(OH)2D3-dependent pathways in the rat osteosarcoma cell line ROS 17/2.8.

The role of hormonal status in the development of aluminum (Al)-dependent renal osteodystrophy, which is characterized by reduced bone matrix deposition, still remains largely unknown. To address this question, we used the osteoblast-like osteosarcoma cell line ROS 17/2.8 to evaluate the role of Al on parathyroid hormone (PTH)- and 1,25-dihydroxyvitamin D3 (1,25(OH)2D3)-dependent activities in these cells.

Type II domains of BSP-A1/-A2 proteins: binding properties, lipid efflux, and sperm capacitation potential.

Bovine seminal plasma contains a family of major proteins (collectively called 1BSP proteins) that potentiate sperm capacitation by binding to capacitation factors such as heparin and by stimulating sperm membrane cholesterol efflux. Here, we investigated the structure-function relationship of type II domains of BSP proteins. We isolated from a tryptic digest of citraconylated BSP-A1/-A2 proteins the intact second type II domain (domain b or Db).

Acute and chronic haemodynamic effects of naftazone in portal hypertensive rats.

It has been demonstrated that hyperproduction of nitric oxide (NO) plays a major role in the vasodilatation of cirrhosis; thus, the vasodilatation might be reversed by an inhibition of NO production. Experimental studies in isolated aortic rings showed that naftazone inhibits the effects of NO production. The aim of this study was to evaluate the haemodynamic effects of acute and chronic administration of naftazone in rats with portal hypertension.

Protein kinase C alterations in aortic vascular smooth muscle cells from rats with cirrhosis.

Background/aims: Alterations in signal transduction in vascular smooth muscle cells may contribute to vascular hyporeactivity in cirrhosis. Protein kinase C plays a role in vascular cell contraction by modifying contractile proteins and intracellular [Ca2+] homeostasis. The aim of this study was to examine the vascular reactivity and expression of protein kinase Calpha in aortae from rats with cirrhosis.

Identification of ceramide-phosphorylethanolamine in oomycete plant pathogens: Pythium ultimum, Phytophthora infestans, and Phytophthora capsici.

Cellular lipids were extracted from three species of Oomycete plant pathogens (Pythium ultimum, Phytophthora infestans, and Ph. capsici) and analyzed via normal-phase high-performance liquid chromatography with flame-ionization detection. The most abundant polar lipids in each of the three species were the polar membrane lipids, phosphatidylethanolamine (PE), phosphatidylcholine, and a phosphosphingolipid that eluted soon after PE.

Pharmacological and biochemical evidence for the regulation of osteocalcin secretion by potassium channels in human osteoblast-like MG-63 cells.

Previous reports have suggested the involvement of voltage-activated calcium (Ca2+) channels in bone metabolism and in particular on the secretion of osteocalcin by osteoblast-like cells. We now report that potassium (K+) channels can also modulate the secretion of osteocalcin by MG-63 cells, a human osteosarcoma cell line. When 1,25-dihydroxyvitamin D3(1,25(OH)2D3)-treated MG-63 cells were depolarized by step increases of the extracellular K+ concentration ([K+]out) from 5-30 mM, osteocalcin (OC) secretion increased from a control value of 218 +/- 13 to 369 +/- 18 ng/mg of protein/48 h (p < 0.

Responsiveness to growth factors in aortic vascular smooth muscle cells from rats with cirrhosis.

Hemodynamic changes in cirrhosis may be associated with alterations in aortic vascular smooth muscle cell (AVSMC) function. The present study compared the proliferative response to serum and growth factors in cirrhotic and control AVSMC. Serum from cirrhotic rats, cirrhotic cell lysates, and the conditioned medium of cultured cirrhotic AVSMC induced an increase in [3H]thymidine incorporation in control but not in cirrhotic AVSMC.

Studies of portal hemodynamics and hepatic oxygen consumption during acute liver allograft rejection.

Hemodynamics and oxygen variables, plasma cytokines, and histological features of a liver tissue sample obtained by transvenous biopsy were evaluated during 65 episodes of acute rejection. The hepatic venous pressure gradient was significantly higher in patients with acute rejection than in those without (5.1+/-0.

Haemodynamic responses to a combination of terlipressin and octreotide in portal hypertensive rats.

Background: An enhancement of the haemodynamic effects of terlipressin by octreotide (and vice versa) may be useful in the treatment of portal hypertension. The aim of this study was to investigate the short-term effects of terlipressin, octreotide or a combination of these substances on splanchnic and systemic haemodynamics in rats with portal vein stenosis.

Methods: Eight rats received an intravenous (i.

Hypoxemia in patients with cirrhosis: relationship with liver failure and hemodynamic alterations.

Background/aims: The relationship between hypoxemia, liver failure and the hemodynamic alterations in cirrhosis are unknown. This study examined the relationship between arterial hypoxemia, the severity of liver disease and hyperkinetic circulation in patients with cirrhosis.

Methods: Arterial blood gases, the severity of cirrhosis (Child-Pugh score), and splanchnic and systemic hemodynamics were measured in 120 patients with cirrhosis and without cardiopulmonary disease.

Haemodynamic effects of octreotide in portal hypertensive rats receiving propranolol.

Background: The aim of this study was to investigate short-term effects of propranolol (a non-selective beta-adrenergic antagonist), octreotide (a long-acting somatostatin analogue), or a combination of these substances on splanchnic and systemic haemodynamics and arterial blood gases in rats with portal vein stenosis.

Methods: Splanchnic and systemic haemodynamics were measured using the radioactive microspheres method. Eight rats first received an i.

The effect of ethanol and oxygen on the growth of Zymomonas mobilis and the levels of hopanoids and other membrane lipids.

Zymomonas mobilis (ATCC 29191) was grown either aerobically or anaerobically in the presence of 2% (wt/vol) glucose and 0, 3, or 6% (vol/vol) ethanol. The rates of growth and the composition of hopanoids, cellular fatty acids, and other lipids in the bacterial membranes were quantitatively analyzed. The bacterium grew in the presence of 3% and 6% ethanol and was more ethanol tolerant when grown anaerobically.

Relationship between portal pressure, esophageal varices, and variceal bleeding on the basis of the stage and cause of cirrhosis.

Background And Methods: Hepatic venous pressure gradient, esophageal varices, and variceal bleeding were investigated in 957 patients with cirrhosis. The causes (alcoholic/virus) and stage (Child-Pugh's classification) of cirrhosis were also taken into account.

Results: The prevalence of variceal bleeding was 35% in patients with large varices and 17% in those with small varices (P < 0.

Natriuretic response to the combination of atrial natriuretic peptide and terlipressin in patients with cirrhosis and refractory ascites.

Background/aims: Refractory ascites, which occurs in certain patients with cirrhosis, is associated with a blunted natriuretic response to exogenous atrial natriuretic peptide (ANP). Since this blunting seems to be related to ANP-induced arterial hypotension, a vasoconstrictor, such as terlipressin (a vasopressin analogue), may restore natriuresis to exogenous ANP. Moreover, since cirrhosis-elicited vasodilation is thought to play a role in sodium retention, a vasoconstriction caused by terlipressin alone may lead to an increase in sodium excretion.

Altered growth and lack of responsiveness to angiotensin II in aortic vascular smooth muscle cells from cirrhotic rats.

Background & Aims: In cirrhosis, increased amounts of circulating hormones such as angiotensin II may induce vascular tone changes and alter vascular smooth muscle cell (VSMC) function and growth. The aim of this study was to investigate the growth of aortic VSMCs from cirrhotic rats with or without the addition of angiotensin II and to determine whether angiotensin II binding was preserved in cirrhotic VSMCs.

Methods: Cirrhosis was induced by bile duct ligation.

Modulation of lipoxygenase activity by bacterial hopanoids.

Tetrahydroxybacteriohopane (1), a bacterial hopanoid, inhibited soybean 15-lipoxygenase with an IC50 of about 10 microM. After per-O-acetylation of 1 no inhibition of the 15-lipoxygenase was observed. Two other bacterial hopanoids, tetrahydroxybacteriohopane glucosamine (2) and tetrahydroxybacteriohopane ether (3), stimulated the activity of soybean 15-lipoxygenase.

Plasma concentrations of cyclic 3', 5'-guanosine monophosphate in patients with cirrhosis: relationship with atrial natriuretic peptide and haemodynamics.

Little is known about the plasma concentrations of cyclic 3',5'-guanosine monophosphate (cGMP) in patients with cirrhosis. However, plasma cGMP concentrations provide information on cellular cGMP production by particulate guanylyl cyclases (which are stimulated by natriuretic peptides, such as atrial natriuretic peptide; ANP). In contrast, because intracellular cGMP elicits vasorelaxant mechanisms, plasma cGMP concentrations may be related to haemodynamic alterations in patients with cirrhosis.

Endothelial calcium-calmodulin dependent nitric oxide synthase in the in vitro vascular hyporeactivity of portal hypertensive rats.

Background/aims: Increased nitric oxide production has been implicated in impaired vascular responsiveness to vasoconstrictors in portal hypertension. However, there is no firm evidence concerning the involved nitric oxide synthase isoform. The present study investigated the possible contribution of one nitric oxide synthase isoform, the endothelial constitutive Ca2+-calmodulin dependent, in the overproduction of nitric oxide in portal hypertension.

Acute effects of propylthiouracil on hemodynamics and oxygen content in patients with alcoholic cirrhosis.

Background/aims: The antithyroid drug propylthiouracil has been suggested for the treatment of alcoholic liver disease. Its beneficial effects could be due to either a decrease in hepatic oxygen consumption or an increase in hepatic blood flow. The aim of this study was to test these two hypotheses in patients with proven alcoholic cirrhosis.