Search results for "Helium"
showing 10 items of 1689 documents
Regulation of Oxygen Distribution in Tissues by Endothelial Nitric Oxide
2009
Nitric oxide (NO) decreases cellular oxygen (O 2 ) consumption by competitively inhibiting cytochrome c oxidase. Here, we show that endogenously released endothelial NO, either basal or stimulated, can modulate O 2 consumption both throughout the thickness of conductance vessels and in the microcirculation. Furthermore, we have shown that such modulation regulates O 2 distribution to the surrounding tissues. We have demonstrated these effects by measuring O 2 consumption in blood vessels in a hypoxic chamber and O 2 distribution in the microcirculation using the fluorescent oxygen-probe Ru(phen) 3 2+ . Removal of NO by physical or pharmacological means, or in eNOS −/− mice, abolishes this …
Mechanisms underlying recoupling of eNOS by HMG-CoA reductase inhibition in a rat model of streptozotocin-induced diabetes mellitus
2007
Abstract Objective HMG-CoA reductase inhibitors have been shown to upregulate GTP cyclohydrolase I (GTPCH-I), the key enzyme for tetrahydrobiopterin de novo synthesis and to normalize tetrahydrobiopterin levels in hyperglycemic endothelial cells. We sought to determine whether in vivo treatment with the HMG-CoA reductase inhibitor atorvastatin is able to upregulate the GTPCH-I, to recouple eNOS and to normalize endothelial dysfunction in an experimental model of diabetes mellitus. Methods and results In male Wistar rats, diabetes was induced by streptozotocin (STZ, 60mg/kg). In STZ rats, atorvastatin feeding (20mg/kg/d, 7 weeks), normalized vascular dysfunction as analyzed by isometric tens…
Chronic Therapy With Isosorbide-5-Mononitrate Causes Endothelial Dysfunction, Oxidative Stress and a Marked Increase in Vascular Endothelin-1 Express…
2011
Aims Isosorbide-5-mononitrate (ISMN) is one of the most frequently used compounds in the treatment of coronary artery disease predominantly in the USA. However, ISMN was reported to induce endothelial dysfunction, which was corrected by vitamin C pointing to a crucial role of reactive oxygen species (ROS) in causing this phenomenon. We sought to elucidate the mechanism how ISMN causes endothelial dysfunction and oxidative stress in vascular tissue. Methods and results Male Wistar rats ( n = 69 in total) were treated with ISMN (75 mg/kg/day) or placebo for 7 days. Endothelin (ET) expression was determined by immunohistochemistry in aortic sections. Isosorbide-5-mononitrate infusion caused si…
Pigment variant of neuronal ceroid-lipofuscinosis
1995
A 6-year-old girl had progressive ataxia, and visual disturbances resulting in blindness. She died in her sleep at age 22 years. She shared with her sister and paternal relatives bilateral pes cavus deformities and impaired deep-tendon reflexes which suggested Charcot-Marie-Tooth disease. Her sister, who also had both polyneuropathy and a progressive central nervous system (CNS) disease, did not have pigmentary retinopathy. At autopsy, the patient was found to have neuronal ceroid-lipofuscinosis (NCL) marked by intraneuronal accumulation of autofluorescent granular lipopigments in ballooned perikarya and conspicuous extraneuronal pigmentation of subcortical grey matter, but without axonal s…
Cell type heterogeneity of intermediate filament expression in epithelia of the human pituitary gland.
1989
In the present study we have localized immunohistochemically the intermediate filament proteins of the human pituitary gland (adenohypophysis, pars intermedia and pars tuberalis) by an indirect immunoperoxidase technique or by double immunofluorescence methods and analysed the individual cytokeratin polypeptides using two-dimensional gel electrophoresis. We found that the expression of cytokeratins in different epithelial cells of the human anterior pituitary gland was heterogeneous. Whereas the endocrine cells only expressed cytokeratins 8 and 18, the folliculo-stellate cells exhibited a reactivity for cytokeratins 7, 8, 18 and 19 as well as for GFAP and vimentin. The squamous epithelial c…
PHOTODYNAMIC THERAPY WITH VERTEPORFIN FOR CHOROIDAL NEOVASCULARIZATION ASSOCIATED WITH RETINAL PIGMENT EPITHELIAL DETACHMENT IN AGE-RELATED MACULAR D…
2007
Abstract PURPOSE: To assess the effectiveness of photodynamic therapy (PDT) with verteporfin for choroidal neovascularization (CNV) associated with retinal pigment epithelium detachment (PED) in age-related macular degeneration. METHODS: Thirty eyes of 26 patients with CNV and PED were treated with PDT. The eyes were divided in two groups based on CNV location in relation to PED; group 1 included 13 eyes with CNV within PED, and group 2 included 17 eyes with CNV at the edge of PED. The median follow-up was 16 months. RESULTS: Patients received a mean +/- SD of 2.83 +/- 1.26 treatments (range, 1-6 treatments). In the whole cohort, the mean preoperative visual acuity changed from 20/144 (0.86…
Diabetes impairs the atrial natriuretic peptide relaxant action mediated by potassium channels and prostacyclin in the rabbit renal artery.
2012
Diabetes is associated with increased prevalence of hypertension, cardiovascular and renal disease. Atrial natriuretic peptide (ANP) plays an important role in cardiovascular pathophysiology and is claimed to have cardioprotective and renoprotective effect in diabetic patients. The working hypothesis was that alloxan-induced diabetes might modify the vascular effects of ANP in isolated rabbit renal arteries and the mechanisms involved in such actions. Plasma ANP levels were higher in diabetic rabbits than in control rabbits. ANP (10(-12)-10(-7)M) induced a relaxation of precontracted renal arteries, which was lower in diabetic than in control rabbits. In arteries from both groups of animals…
Experimental diabetes induces hyperreactivity of rabbit renal artery to 5-hydroxytryptamine.
2002
Abstract The influence of diabetes on the response of isolated rabbit renal arteries to 5-hydroxytryptamine (5-HT) was examined. 5-HT induced a concentration-related contraction that was higher in arteries from diabetic rabbits than in arteries from control rabbits. Endothelium removal did not significantly modify 5-HT contractions in arteries from control rabbits but enhanced the response to 5-HT in arteries from diabetic rabbits. Incubation with N G -nitro- l -arginine ( l -NA) enhanced contractions to 5-HT in arteries from control and diabetic rabbits. In arteries with endothelium, this l -NA enhancement was lower in diabetic rabbits than in control rabbits. In arteries without endotheli…
Phosphodiesterase inhibitors suppress alpha2-adrenoceptor-mediated 5-hydroxytryptamine release from tracheae of newborn rabbits.
1998
The outflow of 5-hydroxytryptamine (5-HT) from isolated tracheae of newborn rabbits was determined by high pressure liquid chromatography with electrochemical detection. This 5-HT outflow reflects release from neuroendocrine epithelial cells of the airway mucosa, as previously shown. Phenylephrine, via alpha2B-adrenoceptors, caused a transient increase in 5-HT outflow, maximally by about 250%, an effect mediated by liberation of intracellular Ca2+, as previously shown. The non-selective phosphodiesterase inhibitor 2-isobutyl-1-methylxanthine (IBMX) concentration-dependently inhibited phenylephrine-induced 5-HT release (completely at 100 microM, IC50: 1.3 microM). Likewise, benzafentrine (in…
Nitric oxide, via activation of guanylyl cyclase, suppresses alpha2-adrenoceptor-mediated 5-hydroxytryptamine release from neuroendocrine epithelial …
1998
Isolated tracheae of newborn rabbits were incubated in vitro and the outflow of 5-hydroxytryptamine (5-HT) was determined by HPLC with electrochemical detection. Evidence has previously been provided that this 5-HT outflow derives from neuroendocrine epithelial (NEE) cells of the airway mucosa. Phenylephrine, at a maximally effective concentration of 10 microM, caused a transient increase in 5-HT outflow by about 250%, an effect mediated by alpha2B-adrenoceptors, as previously shown. The phenylephrine-induced 5-HT release remained unchanged in calcium-free medium, but was reduced by 75% when the tracheae were incubated in calcium-free medium which contained 0.5 mM EDTA, a treatment known to…