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H H Schmidt

Publications and source records attributed to H H Schmidt.

At least 163 records · Page 9Linked to original sources
PubMed1990

Basal and stimulated formation and release of L-arginine-derived nitrogen oxides from cultured endothelial cells.

Endothelium-derived nitrogen oxides, i.e., nitrogen oxide and/or nitrogen oxide-containing compounds, formed from L-arginine account, at least in part, for the biological activity of endothelium-derived relaxing factor(s). We have developed a rapid and sensitive assay to determine the basal and stimulated release of defined breakdown products of endothelium-derived nitrogen oxides, i.e., nitrite and nitrate. Formation and/or release of these nitrogen oxides was time- and concentration-dependently stimulated by various endothelium-dependent vasodilators and was decreased by NG-methyl-L-arginine and L-canavanine, compounds that most likely inhibit the endothelial enzymatic conversion of L-arginine into nitrogen oxides. In addition to nitrogen oxide, hydroxylamine was shown to have pharmacological and physico-chemical properties similar to endothelium-derived relaxing factor(s). Moreover, hydroxylamine release was detected in stimulated bovine aortic endothelial cells. We suggest that hydroxylamine represents one endothelium-derived nitrogen oxide within the group of biologically active nitrogen oxides.

Acetylcholine↗
PubMed1990

Hormone-induced biosynthesis of endothelium-derived relaxing factor/nitric oxide-like material in N1E-115 neuroblastoma cells requires calcium and calmodulin.

Stimulation of soluble guanylyl cyclase in rat fetal lung fibroblasts (RFL-6 cells) was used as a sensitive assay for endothelium-derived relaxing factor/nitric oxide (EDRF/NO) formation. Intact N1E-115 cells released an EDRF/NO-like material that enhanced cyclic GMP levels in RFL-6 cells. The synthesis of this substance could be stimulated with the receptor agonist neurotensin (10 microM) or by addition of the EDRF/NO substrate L-arginine (100 microM). In Ca2(+)-free Locke's solution, stimulation of EDRF/NO production by both neurotensin and L-arginine was abolished. The EDRF/NO-synthesizing activity was localized in the cytosol of N1E-115 cells. The activity was lost after boiling and it was highly sensitive to Ca2+ with the major increase in activity occurring between 100 and 500 nM Ca2+. L-Arginine and NADPH were required for maximal synthesis of EDRF/NO by the enzyme(s). The synthesis of EDRF/NO was inhibited by the following antagonists of calmodulin-regulated functions (with the approximate IC50 values given in parentheses): calmidazolium (7 microM), trifluoperazine (10 microM), fendiline (80 microM), W-7 (N-[6-aminohexyl]-5-chloro-1-naphthalenesulfonamide) (120 microM), and compound 48/80 (3 micrograms/ml). The EDRF/NO-synthesizing activity was partially purified from N1E-115 cytosol by DE 52 anion exchange chromatography. The activity was eluted with 0.1 M KCl. The enzyme(s) showed very little activity in the presence of L-arginine (100 microM) and NADPH (100 microM), but the activity could be fully restored by addition of exogenous calmodulin (EC50, approximately 2 units/ml). At 0.3 M KCl, a fraction eluted from the DE 52 column that was also able to fully restore the EDRF/NO-synthesizing activity. Thus, this fraction is likely to contain the endogenous Ca2(+)-binding protein. It is concluded that the activity of the EDRF/NO-synthesizing enzyme(s) in N1E-115 neuroblastoma cells is regulated by Ca2+ and calmodulin.

Animals↗
PubMed1989

Enzymatic formation of nitrogen oxides from L-arginine in bovine brain cytosol.

In dialyzed bovine brain cytosol, the enzymatic formation of nitrogen oxides was directly determined. The basal formation of nitrite and nitrate was concentration-dependently enhanced by L-arginine (EC50 about 3.10(-5) M). Both the basal and L-arginine induced formations were inhibited by NG-monomethyl-L-arginine (EC50 about 2.10(-4) M). In the presence of L-arginine, a concomitant formation of citrulline was detected. L-Arginine methyl ester also served as a substrate, but neither D-arginine, D-arginine methyl ester nor N alpha-benzoyl-L-arginine ethyl ester did so. The formation of nitrite and nitrate was time-dependent, increased linearly with the protein concentration of the cytosol and was not observed when the cytosolic proteins were heat-denaturated. Exogenous NADPH (or NADP+) concentration-dependently enhanced the formation of nitrite and nitrate, whereas NADH, NAD+, FAD, Ca2+, Mg2+ and calmodulin were ineffective. These results indicate that bovine brain contains a cytosolic enzyme which uses NADPH or NADP+ as cofactors to form nitrogen oxides from both an endogenous non-dialyzable substrate and from L-arginine.

Animals↗
PubMed1989

[Serial infrared and ultraviolet whole body irradiation and placebo and ultraviolet irradiation of autologous venous blood in peripheral arterial occlusive disease. 1. Treadmill ergometry, metabolic, rheologic and hemodynamic parameters].

In 21 patients suffering from obstructive peripheral arterial disease stage II according to Fontaine, therapeutic efficacy of serial whole body irradiations (infrared or ultraviolet radiation) and pretended or real ultraviolet light blood irradiations was evaluated. Before, during and after treatment the following parameters were monitored: walking distance, oxygen partial pressure (quasi-arterial/venous), flow properties of blood (appearant blood viscosity, hemodynamics (peak flow, ultrasonics). There were no significant changes following both modalities of whole body irradiations either by sunshine-like ultraviolet light nor by infrared radiation, nor by pretended blood irradiation. In the same patients mean walking distance was prolonged threefold after ultraviolet irradiation of the patient's own venous blood and subsequent retransfusion. Simultaneously, oxygen utilisation was improved (enlarged arterial/venous difference), lactate concentration was decreased and apparent blood viscosity was diminished, whereas blood flow remained unchanged or only slightly improved. In this way the circulus vitiosus of obstructive peripheral arterial disease can be overcome. As a consequence of blood irradiation walking distance enlarges, providing better chances for physical training, which helps to extend walking distance furthermore.

Adult↗
PubMed1989

Formation and release of nitric oxide from human neutrophils and HL-60 cells induced by a chemotactic peptide, platelet activating factor and leukotriene B4.

Vascular endothelial cells and neutrophils synthesize and release potent vasodilatatory factors, i.e. endothelium-derived relaxing factors (EDRF) and neutrophil-derived relaxing factors (NDRF). One EDRF has been identified as nitric oxide (NO) derived from arginine. We studied the synthesis and release of NO from human neutrophils stimulated with the chemotactic peptide N-formyl-L-methionyl-L-leucyl-L-phenylalanine, platelet activating factor or leukotriene B4. The formation and release of NO was enhanced several-fold in the presence of superoxide dismutase, probably by inhibiting superoxide-induced breakdown of NO. The formation and release of NO but not the formation of superoxide anions was decreased in neutrophils pretreated with L-canavanine, an inhibitor of arginine-utilizing enzymes. Our data suggest that at least one NDRF is identical with NO or another labile NO containing compound derived from arginine.

Bucladesine↗
PubMed1989

Nitric oxide and cytosolic guanylate cyclase: components of an intercellular signalling system.

Endothelial cells, neutrophils, macrophages, and probably various other cells synthesize nitric oxide or a labile NO-containing compound from L-arginine. NO and various NO-containing compounds activate the cytosolic guanylate cyclase, which catalyzes the formation of the second messenger cyclic GMP. This cyclic nucleotide is involved in the regulations of certain target cells as vascular smooth muscle and platelets. Thereby, NO or a labile NO-containing compound and the cytosolic guanylate cyclase are components of an intercellular signalling system.

Animals↗
PubMed1988

[Clinical aspects and functional diagnostic findings of Takayasu disease].

Aetiopathogenesis, clinical picture, laboratorical and functional diagnostic methods of ten patients suffering from Takayasu's arteritis out of 1164 patients suspicious of cerebrovascular insufficiency are described. The combined use of Dopplersonography, ophthalmodynamometry and ophthalmodynamography permit in all cases the assessment of vascular pathology in supraaortic arteries. The specific diagnosis was made in connection which clinical, anamnestical and paraclinical findings. There are some characteristic functional diagnostic results in Takayasu's arteritis. The noninvasive diagnostic methods are useful tools to estimate the progredience of this disease in his chronical course.

Adolescent↗
PubMed1988

Arginine is a physiological precursor of endothelium-derived nitric oxide.

ATP dose dependently stimulated the formation and release of nitric oxide (NO) from perfused rabbit aorta. L-Canavanine, an inhibitor of various L-arginine-utilizing enzymes, abolished basal and ATP-induced NO formation and release. ATP increased the accumulation of presumably NO-derived NO2- in the medium of primary cultures of bovine aortic endothelial cells. 15NO, 15NO2- and 15NO3- formation was found when L-[guanido-15N2]arginine was added to the culture medium. We conclude that the terminal guanidino nitrogens of L-arginine are the physiological precursors of endothelium-derived NO.

Animals↗
PubMed1988

[Ambulatory physical therapy rehabilitation with interval walking-gymnastics therapy in patients with chronic peripheral arterial occlusive disease].

A ambulatory physical therapeutic rehabilitation by means of interval-run-gymnastic-therapy was examined by a prospective study of 43 patients with peripheral arterial disease of the legs and was estimated as practicable. Improvements of walk distance, lengthenings of the pain times in the standardized move up and down-test, decreases of the blood-pressure gradients by ultrasonic Doppler measurements, shortenings of the half-life periods of xenon-clearance, improvements of the metabolism of lactate, improvements of the parameter of metabolism of lipids and uric acid were proved. Successes of therapy were not proved by oscillography and venous occlusion plethysmography. The expense was registered by the loss of working time and discussed.

Ambulatory Care↗
PubMed1984

[Behavior of blood pressure and peripheral hemodynamics in interval therapy in untreated and propranolol-treated patients with arterial circulatory disorders of the lower extremities].

Searching for a possibility of an effective therapy of disturbances of peripheral arterial blood supply (stage I and II), the authors examined a medicamentously untreated group of patients as well as a comparable group of patients which was pretreated with propranolol. The two groups of patients performed twice a week an interval run exercise. Under the three-month training therapy in the two groups significant systolic and diastolic blood pressure reductions as well as statistically ascertained shortenings of the xenon-133-half-value time under working conditions and enlargements of the average functional vascular cross section A appeared. The distance of the intermittent claudication and the standardized moving up and down test prolonged. An influence on the microcirculation caused by propranolol could not be proved. The results are discussed on the basis of literature.

Adult↗
PubMed1983

[Experiences with the application of physiotherapy in peripheral arterial circulatory disorders of the lower extremities (stage I and IIa) under ambulatory conditions].

In a comparative study the authors report on results of series of physical therapy in disturbances of the peripheral arterial blood supply. Examined were the behaviour of blood pressure, the painless walking distance and the peripheral microcirculation with the xenon-133-muscle clearance method before and after treatments lasting 10 to 12 weeks with combined exercises consisting of gymnastics and walking according to the interval principle (twice a week), with sauna visits twice a week as well as before and after diadynamic series of the current. In all therapy groups an improvement of the peripheral haemodynamics could be statistically ascertained. The distance of the intermittent claudication prolonged particularly in the group with interval walking. In the walking group and in the sauna group the values of the systolic blood pressure were significantly reduced. Side-effects were not observed. Therapy effects of the series of physical therapy described are best to be proved by the xenon-133 muscle clearance.

Adult↗