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Biomedical subjects

J Weissenburger

Publications and source records attributed to J Weissenburger.

65 records · Page 4Linked to original sources
PubMedDate not supplied

[Recording of the his bundle potential at the surface of the thorax in healthy volunteers. Application to the study of propranolol].

New analogic-digital technology contributions to standard electrocardiography may allow to record the his bundle potential from the body surface. The aim of this work has been to study the validity of this method by its application to estimate the dromotropic effect of propranolol in healthy volunteers. His bundle potential from body surface was recorded in 19 out of 26 enrolled subjects. The negative dromotropic effect of propranolol (40 mg orally) was observed in only 10 volunteers. The direction of the PR and PH interval changes was used to estimate sensibility (0.9) and specificity (0.89) of this method. There was also a significant correlation (0.89 less than p 0.05) between PR and PH interval changes. This new non-invasive method could be used in clinical pharmacology but the subjects must be preselected.

Adult↗
PubMedDate not supplied

[Hemodynamic effects of medroxalol in the anesthetized dog. Relation between adrenolytic properties and plasma concentration].

Hemodynamic properties of medroxalol (MDL), a new alpha-and-beta adrenoceptor antagonistic drug, were studied in eight pentobarbital-anesthetized (open chest) dogs. MDL was injected in three doses (1.5, 3.0 and 9.0 mg/kg i.v.) at one hour intervals. A control group (n = 5) received three successive vehicle injections at the same time intervals. Heart rate, systolic and diastolic arterial pressure, cardiac output and stroke volume (using an intrathoracic flowmeter), and peripheral resistance were recorded 45 min before the first injection and 15 min after each administration. Isoproterenol (ISP) and neosynephrine (NSP) dose-response curves were recorded before the first dose and after each injection in both group. Log-linear regression analyses were used to estimate the ISP chronotropic dose 25 (DC 25) and the ISP barotropic dose 30 (DB 30). The results show that medroxalol possesses beta-adrenoreceptor antagonistic properties which are 35 times greater than its alpha-antagonistic properties. Beta-blockade was evidenced by bradycardia and increase in DC 25, beginning at the first dose used. Alpha-blockade was not significant at that first dose and therefore cannot alone explain the strong hypotension observed. All these effects were related to the plasma-concentration of MDL.

Adrenergic alpha-Antagonists↗
PubMedDate not supplied

[Quinidine plasma concentration-cardiac electrophysiologic effects relationships in anesthetized dogs (author's transl)].

1. The electrophysiologic effects of quinidine (Q)were studied in 15 pentobarbital-anesthetized dogs using intracardiac electrography and programmed stimulation. With four successive bolus i.v. injections of Q gluconate (1, 3, 9, 18 mg/kg cumulative doses) at 30 min intervals, Q plasma concentration (Cp) ranged from 1.02 +/- 0.1 micrograms/ml to 5.7 +/- 0.6 micrograms at the time of electrophysiologic measurements 20 min after each injection. 2. In six control dogs, heart rate (HR), sinus node recovery time (TRS), conduction times (StH, HV, QRS), ventricular repolarization time (QTc) Wenckebach cycle length (L.W), and atrial refractory periods (RP) did not change significantly while the functional nodal (PRFN) and the effective ventricular (PREV) RPs significantly increased with time. 3. Quinidine produced a significant log- Cp related decrease in HR and increase in TRS corresponding to a decreased sinus automaticity. 4. StH and HV conduction times increased proportionally to log CpQ while the increase in QRS was not Cp-dependent. QTc did not increase significantly. 5. Quinidine resulted in significant log Cp-related increases in atrial RP PRFN and LW while the Q-induced changes in PREV were not Cp-dependent.

Anesthesia↗
PubMedDate not supplied

Study of cyclosporin A blood level during the early post-liver-transplantation period.

Correlations between acute rejection rate, cyclosporin A(CsA) blood level and CsA dose were studied in a group of 58 patients for 1 month following liver transplant. Therapy included prednisolone, azathioprine and CsA administered by continuous IV infusion. Blood CsA levels were measured by high performance liquid chromatography. No patient required renal dialysis. An acute rejection episode was recorded in 24 patients (group 1) between days 4 and 28 (mean 8 days), while 34 patients (group 2) showed no signs of rejection. A significant difference was observed (p < 0.05) between blood CsA levels (mean +/- SEM over the 6 days preceding the rejection episode in group 1 patients, and the first 6 postoperative days in group 2 patients (101 +/- 7 vs 121 +/- 5 ng/ml). The mean daily dose of CsA calculated over the same time period was significantly lower (p < 0.001) in group 1 patients (46 +/- 2 vs 60 +/- 2 mg/day). In addition, over the 8 days following surgery, only 54% of patients in group 1 attained a mean blood CsA level of a least 100 ng/ml, compared to 94% in group 2.

Cyclosporine↗