Search PubMed⌕ Search

Biomedical subjects

J Wagner

Publications and source records attributed to J Wagner.

At least 433 records · Page 24Linked to original sources
PubMed1981

Aging of the erythrocyte XIII. Decrease in nitroxide reducing capacity.

A method is proposed for the determination of nitroxide-reducing capacity (NRC) of erythrocytes, and other cells, based on measurements of reduction of a nitroxide stable free radical in cell suspensions by ESR spectroscopy. Comparison of different age fractions of bovine erythrocytes by this method demonstrates a decrease in NRC during cell aging in vivo.

Animals↗
PubMed1980

Prodrugs of etilefrine: synthesis and evaluation of 3'-(O-acyl) derivatives.

A series of 3'-(O-acyl) derivatives of etilefrine (alpha-[(ethylamino)methyl]-3'-hydroxybenzyl alcohol) was synthesized. Correlations between structure and solubility, pKa value, lipophilicity, and esterase-catalyzed hydrolysis were demonstrated. Of special interest is the 3'-(O-pivaloyl) derivative, which shows, in addition to favorable solubility and improved lipophilicity, marked stability against enzymatic cleavage in blood along with a high rate of hydrolysis in the liver.

Animals↗
PubMed1980

Stimulation by adrenaline and dopamine but not by noradrenaline of myocardial alpha-adrenoceptors mediating positive inotropic effects in human atrial preparations.

In isolated electrically driven right auricular strips of human hearts (1 Hz at 37 degrees C) the ability of the endogenous catecholamines noradrenaline, adrenaline, and dopamine to mediate positive inotropic effects by stimulation of myocardial alpha-adrenoceptors was investigated. 1. The concentration-response curve for the positive inotropic effect of noradrenaline was shifted to the right by pindolol, 10(-8)M, whereas the additional blockade by phentolamine, 3 x 10(-6)M, was without further effect; therefore, the positive inotropic effect of noradrenaline is mediated by beta-adrenoceptors only. 2. In contrast, the positive inotropic effects of adrenaline as well as of dopamine are caused by stimulation of both, beta- and alpha-adrenoceptors. 3. These results are discussed with respect to the possible physiological and pathophysiological function of myocardial alpha-adrenoceptors.

Catecholamines↗
PubMed1980

The lack of a pronounced preference of prenalterol for the beta-l-adrenoceptor subtype.

The beta-sympathomimetic effect of prenalterol was investigated on the electrically driven left atrium as well as on the tracheal chain of the guinea pig. 1. On the atrium driven at 2 Hz prenalterol caused a positive inotropic effect with a pD2-value of 7.0 +/- 0.08 (N = 4). Compared to isoprenaline (1.0) its intrinsic activity amounted to 0.3. 2. On the tracheal chain prenalterol caused very little relaxation. Its intrinsic activity was virtually negligible when compared with those of fenoterol (1.0) or noradrenaline (1.0); it amounted to 0.07 only. 3. On the atrium the positive inotropic effect of prenalterol vanished after 1 hour of incubation. At this time the concentration-response curve for isoprenaline was shifted dose-dependently to the right. The pD2-value for isoprenaline was significantly diminished (P less than 0.001) by prenalterol, 10(-6)M, from 8.36 to 7.14. 4. Likewise, on the trachea prenalterol caused a pronounced, dose-dependent shift of the concentration-response curves for fenoterol as well as for noradrenaline to the right. 5. The results presented here show that on beta-adrenoceptors of the guinea pig prenalterol is acting like a partial agonist in the left atrium, but as full antagonist in the trachea.

Adrenergic beta-Agonists↗
PubMed1980

Physical/chemical and microbiological analyses of dusts at a resource recover plant.

Airborne dusts at a resource recovery pilot plant were sampled and analyzed to determine physical, chemical and microbiological characteristics. The sampling device was a multi-stage impactor equipped with a pre-collector. Dusts are primarily fibrous organic materials, predominantly of nonrespirable size. Microbiological aerosol concentrations are reported and discussed.

Air Microbiology↗
PubMed1980

Depression of sympathetic nervous function by DL-alpha-monofluoromethyldopa, an enzyme-activated, irreversible inhibitor of L-aromatic amino acid decarboxylase.

We investigated the effects on peripheral sympathetic nervous function of monofluoromethyldopa (MFMD, RMI 71963), a selective, enzyme-activated, irreversible inhibitor of L-aromatic amino acid decarboxylase. Three daily injections of 2.5, 25, or 100 mg/kg MFMD to rats reduced the dopamine and norepinephrine concentrations in the heart and increased those of L-dopa. Sedation was seen with the two highest doses of MFMD. Cardiovascular responses in the pithed rat to stimulation of the whole spinal sympathetic outflow and to injections of tyramine were reduced by treatment with MFMD. Both the reduced sympathetic function and the depleted transmitter store were restored by infusions of dopamine. Norepinephrine depletion and functional inhibition were obtained with smaller doses of MFMD (3, 6, and 10 mg/kg daily) given for longer periods (10 days). Blood pressure in spontaneously hypertensive rats was reduced by treatment with MFMD, 25 mg/kg, daily for 3 days. In vitro responses to nerve stimulation of portal veins declined during incubation with MFMD or alpha-methyl-p-tyrosine; responses of atria were unaffected. Changes in norepinephrine concentrations of portal veins and atria closely paralleled the changes in function. MFMD is the first compound which depletes peripheral norepinephrine concentrations by inhibiting transmitter biosynthesis at the decarboxylase step. Such depletion results in inhibition of sympathetic function in vivo and introduces a novel approach to pharmacological manipulation of the activity of the peripheral sympathetic nervous system.

Animals↗
PubMed1980

Two unrelated children with distal long arm deletion of chromosome 7: clinical features, cytogenetic and gene marker studies.

Two phenotypically abnormal, unrelated children with deletion of the distal segment of 7q (7q32 leads to pter) are described. In one instance the mother was the carrier of a balanced translocation between chromosomes 6 and 7, and in the second case the deletion was a de novo event. Their phenotype were compared to previously reported cases and found to have many non-specific clinical features in common. Gene marker studies for some of the genes tentatively localized to chromosome 7 showed no anomalous segregation. The Hageman coagulation factor (Factor XII) activity in both probands was normal, and heterozygosity for alleles of the Kidd blood group in the first proband excludes assignment of the Kidd locus to the distal portion of chromosome 7q.

Abnormalities, Multiple↗
PubMed1980

Further studies on the inhibition of monoamine synthesis by monofluoromethyldopa.

1 alpha-Monofluoromethyldopa (MFMD, RMI 71963), a potent and selective enzyme-activated irreversible inhibitor of aromatic L-amino acid decarboxylase produces a substantial and long-lasting decrease in the catecholamine content of mouse brain, heart and kidney. 2 Single doses of MFMD reduce the 5-hydroxytryptamine concentration of mouse brain without altering the tryptophan concentration. 3 In animals treated with MFMD, peripheral but not brain noradrenaline is restored within 1 h to control levels by an intraperitoneal injection of dopamine.

Animals↗
PubMed1980

Female phenotype and multiple abnormalities in sibs with a Y chromosome and partial X chromosome duplication: H--Y antigen and Xg blood group findings.

A mentally retarded female child with multiple congenital abnormalities had an abnormal X chromosome and a Y chromosome; the karyotype was interpreted as 46,dup(X)(p21 leads to pter)Y. Prenatal chromosome studies in a later pregnancy indicated the same chromosomal abnormality in the fetus. The fetus and proband had normal female genitalia and ovarian tissue. H--Y antigen was virtually absent in both sibs, a finding consistent with the view that testis-determining genes of the Y chromosome may be suppressed by regulatory elements of the X. The abnormal X chromosome was present in the mother, the maternal grandmother, and a female sib: all were phenotypically normal and showed the karyotype 46,Xdup(X)(p21 leads to pter) with non-random inactivation of the abnormal X. Anomalous segregation of the Xga allele suggests that the Xg locus was involved in the inactivation process or that crossing-over at meiosis occurred.

Abnormalities, Multiple↗
PubMed1980

Clinical pharmacology of a new ureidopenicillin: Bay K 49999.

A new semisynthetic ureidopenicillin (Bay K 4999) demonstrates favorably in vitro antibacterial efficacy against human-pathogenic gram-negative rods in comparison to mezlocillin and azlocillin. A comparative paramcokinetic study was done with 10 test subjects after 30 min intravenous infusion of 4.0 g of Bay K and mezlocillin, respectively. The serum concentration course during a period of 10 h showed an open three-compartment model for both antibiotics. The urine recovery of Bay K 4999 during 24 h was only 32.6 +/- 4.3% of the applied dose. In three test subjects with normal renal function, the average renal clearance of Bay K was 61.0, the total serum clearance was 409.2 ml/min/1.73 m2. 31 patients were treated with a daily dose of 3 x 1.0--2.0 g Bay K for severe bronchopulmonary, UTI and cholangiogenic infections. The therapeutic results were good; the relatively high number of side effects should be further investigated in animal studies and require more clinical experience.

Adult↗
PubMed1979

Determination of dopa, dopamine, dopac, epinephrine, norepinephrine, alpha-monofluoromethyldopa and alpha-difluoromethyldopa in various tissues of mice and rats using reversed-phase ion-pair liquid chromatography with electrochemical detection.

A method for the determination of catecholic amino acids and amines by reversed-phase ion-pair high-performance liquid chromatography with electrochemical detection has been developed. B using octanesulfonic acid for ion pairing and by optimising ionic strength, pH and methanol concentration of the mobile phase, separation was achieved of 3,4-dihydroxyphenylalanine (DOPA), 3,4-dihydroxyphenylacetic acid (DOPAC), norepinephrine (NE), epinephrine (EPI), and dopamine (DA). Alpha-Difluoromethyldopa (DFMD) and alpha-monofluoromethyldopa (MFMD), two potent enzyme-activated irreversible inhibitors of aromatic amino acid decarboxylase were also separated from the natural catechols. Concentrations of catechols and inhibitors were measured in brains, hearts and kidneys of mice treated with small repeated doses of MFMD. The method has also been applied to the determination of catechols in other organs such as prostates and seminal vesicles of rats and in smaller tissues like mesenteric arteries. A semi-automated procedure making use of an automatic sample processor and a digital integrator permitted the analysis of as many as sixty samples per day.

Animals↗