Nitric oxide in retinal and choroidal blood flow autoregulation in newborn pigs: interactions with prostaglandins.

The role of nitric oxide (NO) as well as its interaction with prostaglandins (PG) in setting the limits of autoregulation of retinal blood flow (RBF) and choroidal blood flow (ChBF) were studied in newborn pigs (1-5 d old). Blood flows were measured by the microsphere technique. Low and high ocular perfusion pressures (OPP) were induced by inflating balloon-tipped catheters placed at the aortic root and isthmus, respectively.

Contractile effects of vanadate on aorta rings from virgin and pregnant rats.

The present study was undertaken to characterize the contractile effects of vanadate on thoracic aorta rings from virgin and term-pregnant rats. Vanadate caused concentration-dependent contraction in rat aortic rings with an EC50 (concentration producing 50% maximum response) of 0.10 mM.

Stimulation of non-oxidative glucose utilization by L-carnitine in isolated myocytes.

The effects of L-carnitine on 14CO2 release from [1-14C]pyruvate oxidation (an index of pyruvate dehydrogenase activity, PDH), [2-14C]pyruvate, and [6-14C]glucose oxidation (indices of the acetyl-CoA flux through citric acid cycle), and [U-14C]glucose (an index of both PDH activity and the flux of acetyl-CoA through the citric acid cycle), were studied using isolated rat cardiac myocytes. L-carnitine increased the release of 14CO2 from [1-14C]pyruvate, and decreased that of [2-14C]pyruvate in a time and concentration-dependent manner. At a concentration of 2.

Angiotensin II receptor subtypes in the adrenals of pregnant rats.

During human and rat pregnancy, several hemodynamic and endocrine processes are markedly modified. These include activation of the renin-angiotensin system (RAS) and increase of plasma aldosterone. However, the rise of plasma aldosterone is greater than expected from the elevation of RAS activity.

Effects of nifedipine and Bay K 8644 on myotropic responses in aortic rings of pregnant rats.

The hypothesis that Ca2+ channel function is altered during pregnancy was tested by comparing responses to potassium chloride (KCl) and phenylephrine in aortic rings of virgin and term-pregnant rats under the influence of nifedipine and Bay K 8644. Maximum response to KCl was progressively reduced by increasing nifedipine concentrations (1.0-100 nM) in both groups of tissues.

Decreased response to vasopressin in the mesenteric resistance arteries of pregnant rats: effects of nifedipine and Bay K 8644.

Objective: The purpose of this study was to investigate the contribution of potential-operated calcium (POC) channels in the mechanisms of the blunted effects of vasoconstrictors on mesenteric resistance arteries during normal pregnancy.

Methods: Mesenteric resistance arteries of virgin and term pregnant rats were set up under optimum passive tension in wire myograph systems. Cumulative concentration-response curves of arginine8-vasopressin (AVP) were measured in the absence and presence of nifedipine or Bay K 8644, a blocker and an activator, respectively, of POC channels.

Lewis rat T cells can reutilize, process, and present myelin basic protein to antigen-specific T cell lines.

MHC class-II-negative astrocytes prevented from intracellular antigen (Ag) processing induce myelin basic protein (MBP)-specific short-term T cell lines to proliferate. This process results from the ability of the T cells themselves to take up, process, and present Ag to each other. The Ag-presenting function of the T cells occurred in the absence of any conventional antigen-presenting cell (APC), was independent of their T cell receptor specificity, was sensitive to chloroquine, and was prevented by anti-class-II MHC antibody.

Reduction of conjugated dienes in lung transplantation: effect of BN 52021.

Oxygen-derived free radicals have been identified as the mediators of tissue injury during reperfusion in organ transplantation. Lipid peroxidation of cell membrane polyunsaturated fatty acids, generating conjugated dienes (CD), is a toxicity of oxygen-derived free radicals. The CD structure in fatty acyl moieties was measured by high-pressure liquid chromatography in samples of inferior pulmonary venous blood and pulmonary tissue to assess reperfusion injury and oxygen-derived free radical-mediated damage in a canine model of left lung allotransplantation.

Costimulator deficient antigen presentation by an endothelial cell line induces a nonproliferative T cell activation response without anergy.

The ability of endothelial cells to activate helper T (Th) cells by antigen presentation was studied using the murine endothelial cell line SVEC4-10 and antigen-specific murine T cell clones. SEVEC4-10 cells constitutively express vascular cell adhesion molecule 1 but not intercellular adhesion molecule 1. Interferon gamma (IFN-gamma) treatment of these cells induced class II major histocompatibility complex (MHC) expression and antigen-presenting capabilities, but did not alter surface integrin expression.

Umbilical and placental vessels: modifications of their mechanical properties in preeclampsia.

Objectives: Our objective in this study was to assess the basic mechanical properties of umbilical and chorionic vessels of placentas delivered after both normal and preeclamptic pregnancies.

Study Design: Placentas were selected when the parturient women were admitted to the delivery room. Normal pregnancy (n = 17) was characterized by delivery at term (38 to 40 weeks) after uncomplicated pregnancy without any medication.

Myelin-liposome protection against experimental autoimmune encephalomyelitis is associated with reduced neuroantigen-specific T-cell-mediated responses.

Lewis rats undergo a relapsing paralytic disease upon challenge with spinal cord emulsified in complete Freund's adjuvant (CFA). Treatment with two intracardiac injections of liposomes composed of whole myelin significantly reduced the severity of disease. Protection was disease-specific since treatment with myelin liposomes did not protect Lewis rats against adjuvant arthritis (AA), a CNS-unrelated T-cell-mediated autoimmune disease.

Vascular atrial natriuretic factor receptors in spontaneously hypertensive rats.

Objective: The aim was to investigate vascular receptors for atrial natriuretic factor (ANF) in spontaneously hypertensive (SHR), Wistar-Kyoto (WKY), and Wistar rats (WR) at different ages.

Methods: Relaxation and guanylate cyclase responses of blood vessels to atrial natriuretic factor were investigated, as was the binding of 125I-ANF to vascular membranes and ANF receptor subtypes, using sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) in reducing conditions, after solubilisation and irreversible binding of 125I-ANF.

Results: Vascular relaxation responses of aorta showed an increased sensitivity to ANF in four week old SHR [pD2 = 8.

Platelet activating factor antagonist enhances lung preservation.

Platelet activating factor (PAF) is a potent phospholipid mediator of the immune and inflammatory responses, which causes physiologic effects similar to post-transplant pulmonary dysfunction. This study investigates the hypothesis that the use of a specific PAF antagonist (PAFA), BN 52021, in canine lung transplantation improves lung preservation. Twelve pairs of canines underwent left lung allotransplantation after pulmonary artery flushing with modified Euro-Collins (EC) solution (40 ml/kg).

Donor heart valves: electron microscopic and morphometric assessment of cellular injury induced by warm ischemia.

Cryopreserved allograft valves are increasingly being used as valvular replacements. Leaflet fibroblast viability has been suggested to influence clinical durability. The warm ischemic time is thought to be a critical determinant of this cell viability.

Effect of anti-interferon-gamma and anti-interleukin-2 monoclonal antibody treatment on the development of actively and passively induced experimental allergic encephalomyelitis in the SJL/J mouse.

SJL/J mice challenged with myelin basic protein (MBP) in complete Freund's adjuvant (CFA) developed only mild chronic-relapsing experimental allergic encephalomyelitis (EAE) with very low incidence. However, treatment of challenged mice with anti-interferon-gamma (IFN-gamma) monoclonal antibody (mAb) determined severe disease in all cases. Similarly, in passive EAE, the addition of anti-IFN-gamma to the in vitro MBP-activated cells at the time of transfer led to significant disease exacerbation in all recipients.

Prostaglandin- or endothelium-mediated vasodilation is not involved in the blunted responses of blood vessels to vasoconstrictors in pregnant rats.

Pregnancy is associated with decreases of blood pressure and vascular sensitivity to vasopressor agents. We have hypothesized that the increased liberation of endogenous vasodilator(s) by the vascular endothelium or other structures could mediate these blunted responses. Thoracic aorta rings of nonpregnant, 21 days pregnant, and first day post partum rats respond similarly to acetylcholine, an endothelium-dependent vasorelaxant.

Ross' first homograft replacement of the aortic valve.

Ross' first homograft replacement of the aortic valve was reported in 1962. The homograft has been in continuous use around the world ever since. Much has been learned about how to handle homografts, both before and during their implantation.

Effect of clentiazem on lipid profile, lipoprotein composition and aortic fatty streaks in cholesterol-fed rabbits.

Numerous experimental studies have reported that common antihypertensive drugs such as diuretics, beta-blockers, and methyldopa have adverse effects on plasma lipids and lipoproteins. The present study was designed to define the effect of clentiazem (10 mg/kg/day) an antihypertensive drug, on hyperlipidemia in rabbits on a cholesterol-rich diet (1%) for 12 weeks. Compared with controls, clentiazem treated rabbits had lower plasma concentrations of triglycerides (55%), total cholesterol (24%), free cholesterol (27%), esterified cholesterol (23%) and phospholipids (24%).

Receptors for Arg8-vasopressin, angiotensin II, and atrial natriuretic peptide in the mesenteric vasculature of pregnant rats.

Blood pressure and sensitivity of blood vessels to vasoconstrictors are decreased in term-pregnant rats (20-21 days). To determine if changes in receptors for vasoactive peptides could account for these observations, receptor kinetics were measured for Arg8-vasopressin (AVP), angiotensin II (Ang II), and atrial natriuretic peptide (ANP) in the mesenteric vascular bed of the rat throughout pregnancy. Receptors for AVP were statistically similar in the five groups of animals (nonpregnant; pregnant 9, 15, and 21 days; and postpartum).

Effects of warm ischemia following harvesting of allograft cardiac valves.

The clinical use of cryopreserved allograft valves is rapidly increasing. Viability of valve leaflet fibroblasts has been proposed to be critical to durability. Harvesting of allograft valves involves variable warm ischemia times, defined as the time from cessation of donor heart beat to initial cooling for transport.

Role of the endothelium in adrenergic responses of mesenteric artery rings of pregnant rats.

Responses to adrenergic agents were measured on rings of mesenteric, artery of nonpregnant and pregnant rats at 21 days' gestation. In tissues from pregnant rats, norepinephrine, and phenylephrine were less sensitive than in rings from nonpregnant animals; maximum responses were not affected. The effect of isoproterenol was not modified in tissues from pregnant rats.

Treatment of spinal cord-induced experimental allergic encephalomyelitis in the Lewis rat with liposomes presenting central nervous system antigens.

Chronic-relapsing experimental allergic encephalomyelitis (CR-EAE) in the Lewis rat, induced by the injection of spinal cord tissue in complete Freund's adjuvant (SC/CFA), was studied in vivo by treatment with liposomes containing central nervous tissue antigens, and in vitro by lymphocyte proliferation assays. Intracardiac administration of myelin basic protein (MBP) liposomes, galactocerebroside (GC) liposomes, or MBP + GC liposomes substantially reduced the clinical severity and/or delayed the onset of the initial phase of disease. Liposomes prepared from whole myelin provided even greater protection, and were effective at suppressing both the first disease episode and the relapses.

Suppression of experimental allergic encephalomyelitis by MBP-coupled lymphoid cells and by MBP-liposomes: a comparison.

In previous experiments, we showed that administration of myelin basic protein (MBP) inserted into phosphatidyl-serine liposomes, to susceptible animals suppressed the clinical manifestations of both acute and chronic-relapsing EAE. In this report we compare the effectiveness of treatment with MBP-liposomes and with MBP-coupled syngeneic spleen cells in EAE protection. Lewis rats treated with 150 micrograms MBP-liposomes or with 160 micrograms (35 x 10(6] MBP-coupled spleen cells, given 7 days before and 7 days after encephalitogenic challenge were equally protected against clinical EAE, when compared to untreated controls.