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Biomedical subjects

F Brunner

Publications and source records attributed to F Brunner.

At least 37 records · Page 2Linked to original sources
PubMed1990

Five-year survival for end-stage renal disease patients in the United States, Europe, and Japan, 1982 to 1987.

We compared the 5-year survival for new end-stage renal disease (ESRD) patients accepted for renal replacement therapy (RRT) between 1982 and 1987 in the United States (n = 150,862), Europe (European Dialysis and Transplant Association [EDTA]) (n = 124,796), and Japan (n = 66,244). Given these large samples that approach a census in each of the three regions, all results are statistically significant. Our analysis showed that the US patients were older and more likely to be diabetic than the patients in either EDTA or Japan. After correction for patient differences in age composition and the percent diabetic, Japan had the highest survival, followed by EDTA, and then the US. Overall, the US 5-year survival was 40%. When comparison is done by age, only the youngest patients in the US (less than 15 years) have longer survival than their counterparts in Europe and Japan. For ages greater than 14 years, the survival differences between the US and EDTA and between the US and Japan grow larger with higher patient age. The comparisons of mortality by diagnosis showed that the differences between the US and EDTA and between the US and Japan were least for diabetes. For non-diabetic patients, the age adjusted relative risk (RR) of mortality for the US compared with EDTA was 1.22, ie, 22% higher in the US; for the US compared with Japan, the RR was 1.40. In contrast, the RR for diabetic patients in the US compared with EDTA was 1.07, and 1.23 for the US compared with Japan.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

Bretylium tosylate binds preferentially to muscarinic receptors labelled with [3H]oxotremorine M (SH or 'high affinity' receptors) in rat heart and brain cortex.

Bretylium tosylate is an antiarrhythmic agent. In guinea pig atria it showed the properties of a competitive muscarinic (cholinergic) antagonist and could distinguish between two muscarinic receptor classes or states in cardiac membranes. We decided to further investigate its binding properties at muscarinic cholinergic receptors of the rat heart and brain (cortex), keeping in mind the recently discovered heterogeneity of muscarinic receptor protein. Bretylium tosylate recognized two receptor classes or states in the heart with Ki values of 0.9 and 11 microM. All cardiac membrane receptors showed a homogeneous (11 microM) Ki value for the drug in the presence of GTP in the incubation medium, or after in vivo pretreatment with islet activating protein (IAP). Bretylium tosylate was able (but only at a high concentration, 1 mM) to slow the dissociation kinetics of the tracer, which suggests that it also bound to an allosteric site on the muscarinic receptor, or that it affected the receptor environment. In the brain cortex, as in the heart, bretylium tosylate displayed a high affinity for receptors labelled with the agonist [3H]oxotremorine M (Ki value: 0.8 microM for the SH-or cardiac-type high-affinity receptors), and a 8- to 10-fold lower affinity for cortex M and L receptors. These data suggest that the antagonist bretylium tosylate had binding properties in rat cardiac membranes analogous to those of the partial agonist pilocarpine and that it interacted with a single type of receptor.

Animals↗
PubMed1989

Interaction of DPI 201-106 with cardiac muscarinic receptors.

The effects of the new cardiotonic compound, DPI 201-106, on muscarinic responses and muscarinic receptor binding were studied in the guinea pig heart. DPI 201-106 exerted a pronounced anticholinergic action in isolated auricles and a moderate one in papillary muscles, which resembled the pattern of a functional antagonism. However, in competition binding experiments, DPI 201-106 inhibited binding of the specific muscarinic antagonist [3H]NMS with equal potency in atrial and ventricular homogenates (apparent KI = 0.7 mumol/l in atria and 1.2 mumol/l in ventricles). At higher concentrations (greater than 3 mumol/l), DPI 201-106 slowed the dissociation of [3H]NMS from cardiac muscarinic receptors, indicating that DPI 201-106 affects in addition a site allosteric to the muscarinic receptor. It is concluded that DPI 201-106 is able to inhibit cholinergic responses in the heart, not only by a functional antagonism but also by direct interaction with muscarinic receptors.

Animals↗
PubMed1989

Comparative effects of haemodialysis and haemofiltration on plasma atrial natriuretic peptide.

The effects of 4 h haemodialysis (15 patients) or 4 h haemofiltration (five patients) on plasma concentrations of atrial natriuretic peptide (ANP) were compared by means of a sensitive radioreceptor binding assay, and related to accompanying changes in body weight, blood pressure and plasma renin activity. Before dialysis, plasma ANP concentrations were considerably elevated: haemodialysis group 10-484 pmol/l (mean 156 pmol/l); haemofiltration group 72-320 pmol/l (mean 170 pmol/l). Although plasma concentrations of ANP fell markedly with treatment in both groups: post-haemodialysis 2-187 pmol/l (mean 67 pmol/l); post-haemofiltration 47-135 pmol/l (mean 79 pmol/l), after treatment it remained above the normal range in 14 of the 20 patients. Pretreatment plasma ANP was related to systolic blood pressure (r = 0.459; P less than 0.05) but bore no relationship to mean or diastolic blood pressure, or plasma renin activity. The fall in plasma ANP concentration during treatment correlated with the postural blood pressure drop after dialysis (r = 0.505; P less than 0.05), but was unrelated to changes in weight or plasma renin activity with haemodialysis or haemofiltration. Plasma ANP concentrations rose rapidly again in the 60 min after dialysis treatment, without change in body weight. These results show that high levels of biologically active ANP circulate in end-stage renal disease. The fact that these are not reduced to normal by haemodialysis or haemofiltration, despite restoration to normovolaemic or hypovolaemic state, suggests that the increased levels of ANP in end-stage renal failure are due to both hypervolaemia and other factors, which may include occult cardiac dysfunction and loss of renal clearance.

Adult↗
PubMed1989

Subclassification of atrial and intestinal muscarinic receptors of the rat--direct binding studies with agonists and antagonists.

1. Although extensively investigated, the extent of differences between receptors mediating negative inotropic and chronotropic responses is still unclear. In the present study atrial and intestinal muscarinic receptors were identified by [3H]-N-methyl-scopolamine ([3H]-NMS) binding and the affinities of some presumably inotropy- or chronotropy-selective agonists and several antagonists determined. 2. All the agonists tested showed similar affinity for right and left atrial receptors. Accepting an affinity difference of 0.4 log units as experimental error, none of the agonists tested was selective for either atrium. 3. Affinity differences of the cardioselective antagonists himbacine, AF-DX 116 and methoctramine and the M1-selective antagonist dicyclomine for right and left atrial muscarinic receptors were also minimal (less than 2 fold selective). When compared to intestinal receptors, AF-DX 116 was 3 to 4 fold, methoctramine 10 to 13 fold selective and himbacine and dicyclomine non-selective. 4. These data provide evidence for differences between atrial and intestinal but not between right and left atrial muscarinic receptors.

Acetylcholine↗
PubMed1989

Incidence of arrhythmias and myocardial ischaemia during haemodialysis and haemofiltration.

Thirty-two patients (10 male, 22 female; age 37-82 years) undergoing maintenance haemodialysis or haemofiltration were studied by means of Holter device capable of simultaneously analysing rhythm and ST-changes in three leads. Twenty-five patients were on haemodialysis, seven on haemofiltration, mean duration of haemodialysis/haemofiltration being 3.4 +/- 3 years. Incidence of ventricular tachycardia was low, being detected only in 1 of 32 patients. Ventricular premature beats in excess of 10/h during a period of 2 h were found in 8 of 32 patients and 100 supraventricular premature beats for 2 h or more in 4 of 32 patients. Both ventricular premature beats and supraventricular premature beats were most frequently recorded during the last hour of haemodialysis/haemofiltration. ECG signs of ischaemia were detected in eight patients, four of whom were asymptomatic. Ischaemia also occurred predominantly during the last hour of haemodialysis/haemofiltration. Two symptomatic patients displayed neither arrhythmias nor ST-changes while being monitored. The study shows that silent ischaemia and arrhythmias in patients undergoing chronic haemodialysis/haemofiltration may not be infrequent. Recognition of these events could be of importance in the management of these patients.

Adult↗
PubMed1989

Pharmacokinetics and metabolism of the antiarrhythmic agent [3H]-diprafenone in the rat.

After acute intravenous (i.v.) administration of 3 mg/kg of 3H-labelled 2'[2-hydroxy-3-(1,1-dimethylpropylamino)propoxy]-3-phenylproiop henon hydrochloride ([3H]-diprafenone), plasma radioactivity levels declined biphasically with half-lives of 0.2 h (alpha-phase) and 1.5 h (beta-phase), respectively. After acute oral administration of 9 mg/kg, absorption was prompt but continued, similar to a zero-order process, over many hours resulting in plateau-like plasma levels up to 5-6 h and a subsequent slow decline with a beta-half-life of 6-8 h. Absorption varied between 50 and 80%. Distribution of [3H]-diprafenone was rapid and tissue levels in general paralleled blood levels. After i.v. dosing highest levels of radioactivity were found in the lung; after oral application in the gastrointestinal tract. Radioactivity was distributed into subcellular organelles and the cytosol resulting in an apparent volume of distribution (Varea) of 4-5 l/kg. About 95% of the 3H-activity given was excreted in urine (20%) and faeces (75%) within 48 h after i.v. administration. After oral application, total 3H-recovery was substantially lower. After i.v. dosing most of the 3H-label found in faeces originated from biliary excretion and was almost completed within 4 h after administration. After oral application, biliary excretion varied between about 5 and 35% indicating protracted absorption. 3H-radioactivity was reabsorbed and subject to extensive enterohepatic cycling. After repetitive oral administration, total radioactivity reached a steady state after 4-5 days. The corresponding cumulation factors R ranged between 2 and 3. A decline in elimination rate is likely. [3H]-Diprafenone was metabolized rapidly and quantitatively.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1988

Characterization of guinea-pig cardiac muscarinic receptors by radioligand dissociation kinetics.

The question of cardiac muscarinic receptor heterogeneity was studied in guinea-pig auricles and ventricle. Radioligand dissociation kinetics were analyzed in the absence and presence of alinidine and AQ-A 39, two muscarinic agents and allosteric modulators of radiotracer dissociation. The dissociation kinetics were monophasic with all 3 radiotracers used and in both auricles and ventricle. [125I]3-Quinuclidinyl 4-iodobenzilate ([125I]QNB) dissociated with an identical half-life (t1/2 off) in ventricle and in left and right auricle, respectively. Alinidine (1 mM) decreased t1/2 off by 50% in ventricle but had no significant influence in auricles. AQ-A 39 (= falipamil) uniformly increased t1/2 off 4-fold in all 3 tissues. The binding of tritium-labelled quinuclidinyl benzilate ([3H]QNB) dissociated equally rapidly from both ventricular and auricular receptors under control conditions but was not affected by alinidine. AQ-A 39 (1 mM) slowed [3H]QNB dissociation 6.5-fold in ventricle but only 3-fold in both auricles. [3H]N-Methyl scopolamine ([3H]NMS) dissociation was uniform in both auricles but was somewhat slower in the ventricle, both in the absence and presence of alinidine. AQ-A 39 was without effect. These results demonstrate differences in ventricular versus auricular receptors detected by [125I]QNB in the presence of alinidine and by [3H]QNB in the presence of AQ-A 39. The quaternary ligand [3H]NMS was unable to detect receptor heterogeneity. No differences were found between right and left auricular receptors. The results presented provide no evidence for the existence of different subtypes of muscarinic receptors for the negative chronotropic and inotropic actions of muscarinic agonists.

Allosteric Site↗
PubMed1988

Binding of two specific bradycardic agents, alinidine and AQ-A 39, to muscarinic receptors of guinea pig atria and ventricle.

The mechanism of action of the two "specific bradycardic agents" alinidine and AQ-A 39 (falipamil) is still a matter of controversy. Their binding properties to atrial and ventricular myocardium of the guinea pig and rat were, therefore, investigated by the radioligand binding technique. In competition studies against the nonselective antagonists [125I]3-quinuclidinyl 4-iodobenzilate [( 125I]QNB) and 1-N-methyl-[3H]scopolamine methylchloride [( 3H]NMS), both alinidine and AQ-A 39 competitively displaced the radioligands with I50 values (corrected for radioligand concentration) of 1-2 microM (alinidine/[125I]QNB) and 4 microM (alinidine/[3H]NMS), respectively. The I50 values for AQ-A 39 were lower by a factor of two. Slope factors (pseudo Hill coefficients) were 0.7-0.8 (AQ-A 39) and 0.8-0.9 (alinidine), and significantly lower than unity in both atria and ventricle. The guanosine triphosphate (GTP) (100 microM) and 5'-guanylimido-di-phosphate [Gpp(NH)p] (100 microM) slightly creased [3H]QNB binding and produced no or only a small (factor 2-3) rightward shift of alinidine and AQ-A 39 competition curves. At high concentration (1 mM), AQ-A 39 drastically decreased [125I]QNB dissociation rate from both atrial and ventricular receptors (t1/2 control, 19 min; plus AQ-A 39, 75 min) while alinidine (1 mM) decreased dissociation half-life in ventricle with no change in atria. It is concluded that both bradycardic agents possess some but not all characteristics of weak agonists in binding studies, and that they also bind to an allosteric site of the muscarinic receptors. Association with this site could possibly activate a mixed Na+/K+ inward pacemaker current (if) resulting in bradycardia.

Animals↗
PubMed1987

The stereoselectivity of the 'single drug binding site' of human alpha 1-acid glycoprotein (orosomucoid).

The stereoselective binding of six pairs of basic, one pair of acidic drug enantiomers, and one pair of diastereomers for human alpha 1-acid glycoprotein was investigated by means of competition experiments against [3H]propranolol- or [14C]nicardipine-labelled binding sites using equilibrium dialysis to separate free from bound marker ligand. The affinity constants (Ka) for association of [3H]propranolol and [14C]nicardipine with alpha 1-AGP were 1.2 +/- 0.6 X 10(5) M-1 and 3.4 +/- 1.4 X 10(5) M-1, respectively, and control binding amounted to 57 +/- 7 and 91 +/- 2%, respectively. The following selectivity factors, calculated as the ratio of the higher over the lower enantiomer concentrations displacing 15% of control radiomarker binding (IC15-value), were obtained against propranolol and nicardipine: (-)/(+) propranolol: 1.9 and 1.7.; (+)-/(-)-disopyramide: 2.8 and 1.4; (+)-/(-)-verapamil: 1.6 and 1.9; (+)-(S)-/(-)-(R)-202-791, a dihydropyridine derivative: 2.6 and 2.0; (-)-/(+)-asocainol: 1.7 and 3.0; (+)-/(-)-tilidine: 1.1 and approximately equal to 2; (-)-(S)-/(+)-(R)- warfarin: 1.6 and 2.4; (+/-)-cis/(+/-)-trans-trans-tilidine: 1.7 and 1.8. When the calculation of radioligand-free fractions is also taken into account, it is apparent that only the tilidine isomers show no selectivity at propranolol-marked, and the disopyramide isomers at nicardipine-marked alpha 1-AGP-binding sites, in all other cases, a weak selectivity is detectable, which is, however, far below the values obtained for most neurotransmitter receptors. It is concluded that the single drug binding site of alpha 1-AGP is only slightly stereoselective and that the stereoselective binding of the drugs investigated is probably of no clinical consequence.

Binding Sites↗
PubMed1987

Dithranol: further investigations on the structure-activity-relationship. The new series of the 10-mono-alkyldithranol derivatives.

The in vitro stability of 10-ethyldithranol (1,8-dihydroxy-10-ethyl-9(10H)-anthracenone) and its effects on healthy and psoriatic skin is investigated. 10-Ethyl-dithranol as a representative of the new class of 10-alkyldithranol derivatives neither stains nor irritates and has no antipsoriatic activity at all. This is due to the relatively stable substituent at carbon 10 which enables the fast oxidation processes necessary for the antipsoriatic effect. Therefore, antipsoriatically active dithranol derivatives require a free or easily liberated 10-position and hence the so-called 'minimum structure of antipsoriatic anthrones' keeps its validity.

Anthralin↗
PubMed1987

[Removal of tattoos with the Nd:YAG laser].

Irradiation of 20 tattoos using the Q-switched Nd:YAG laser (energy density 3-5 J/cm2, asymmetrical pulse shape with 50% energy output in 18 ns, spot size 3 mm in diameter) gave the impression that black ink tattoos can be completely removed without scarring. Some patients needed several treatments. The results continued to improve even some months after the irradiation. In preliminary experiments on excised tattooed and untattooed skin the non-Q-switched Nd:YAG laser had distinct burning effects. It was therefore not tested in patients. The results of chemical, physical, and histological examinations are discussed with special reference to toxic side-effects that might be induced by laser irradiation.

Humans↗
PubMed1986

Secoverine is a non-selective muscarinic antagonist on rat heart and brain receptors.

In an attempt to determine if the selectivity of secoverine observed in vivo and in isolated tissues might be due to selective association with muscarinic receptor subtypes, we analyzed the binding of secoverine to three different receptors with specific radioligands: rat cardiac receptors (M2 receptors with low affinity for atropine), and rat cerebral cortical M1 receptors and M2 receptors with high affinity for atropine. At concentrations up to 10(-6) M, secoverine interaction with muscarinic receptors was competitive and of high affinity (Ki 4.10(-9) M) for cardiac and brain receptors. A detailed analysis using, in addition to [3H]N-methylscopolamine, the agonist [3H]oxotremorine-M (selective for high affinity binding sites at cardiac receptors) and the M1-selective antagonist [3H]pirenzepine at brain receptors, revealed identical affinities towards both receptor types, making it unlikely that secoverine distinguished the different muscarinic receptor subtypes. At concentrations between 10(-6) and 10(-3) M, secoverine interaction with an additional receptor site resulted in profound changes of tracer kinetics, suggesting the formation of a ternary complex (secoverine-radioligand-muscarinic receptor). The potency of secoverine for provoking this allosteric interaction was both tracer- and tissue-dependent. It is concluded that secoverine does not differentiate between M1, brain M2 and cardiac M2 receptors or between cardiac receptors with high, low and very low affinity for agonists. At very high concentrations secoverine recognized an allosteric site on the muscarinic receptors and reduced the dissociation rates of the 3H-ligands.

Allosteric Site↗