超声波清洗器对大鼠心电图的影响

目的考察超声波清洗器对大鼠的影响。方法用RM6240多道生理信号采集处理系统,采用标准肢体二导联法测量正常状态和超声波清洗器工作时麻醉大鼠的心电图。结果超声波清洗器打开后2 min、15 min和30 min时,麻醉大鼠的心率显著增加,心电图的QRS波群间期显著缩短。而超声波清洗器停止工作后30 min时,大鼠心率和QRS波群间期基本恢复至正常。结论超声波清洗器工作时对大鼠心脏可产生一过性的不良影响。因此,在动物饲养或实验区内,超声波清洗器的放置应远离大鼠饲养室。     

UV-Light Effects on Cytochrome C Modulated by the Aggregation State of Phenothiazines

The present study shows the factors that modulate the photodamage promoted by phenothiazines. Cytochrome c was irradiated with UV light for 120 min, over a pH range from 4.0 to 8.0, in the absence and in the presence of different concentrations of thioridazine (TR) and fluphenazine (FP). In the absence of phenothiazines, the maximal rate of a Soret band blue shift (nm/min) from 409 to 406 nm was obtained at pH 4.0 (0.028 nm/min). The presence of phenothiazines at the concentration range 10-25 µmol/L amplified and accelerated a cytochrome c blue shift (409 to 405 nm, at a rate = 0.041 nm/min). Above 25 µmol/L, crescent concentrations of phenothiazines contributed to cytochrome c protection with (maximal at 2500 µmol/L). Scanning electronic microscopy revealed the formation of nanostructures. The pH also influenced the effect of low phenothiazine concentrations on cytochrome c. Thus, the predominance of phenothiazine-promoted cytochrome c damage or protection depends on a balance of the following factors: the yield of photo-generated drug cation radicals, which is favored by acidic pH; the stability of the cation radicals, which is favored by the drug aggregation; and the cytochrome c structure, modulated by the pH.     

Phenothiazines are slowly oxidizable substrates of horseradish peroxidase

Reactions of peroxidase oxidation of triftazine and thioproperazine have been investigated in the presence of horseradish peroxidase using steady state kinetic methods. It has been shown that phenothiazines are slowly oxidizable substrates for horseradish peroxidase. k _cat and K _m values have been determined in the range of pH from 4.5 to 7.5. The study of co-oxidation of phenothiazines and o-dianisidine (ODN) revealed that in the presence of aminazine and ODN in the reaction medium both substances follow sequential oxidation. ODN oxidation was not observed until full conversion of aminazine. At pH 4.5–5.5 thioproperazine bound to the enzyme-substrate complex and caused anticompetitive inhibition of peroxidase. At pH > 5.5 sequential substrate oxidation with preferential thioproperazine conversion occurred. In the range of pH from 4.5 to 7.5 triftazine did not influence ODN oxidation.     

Phenothiazines and structurally related compounds as inhibitors of adenosylmethionine decarboxylase: effects on the purified enzyme

The effects of chlorpromazine, imipramine, thioridazine, chlorprothixene, amitriptyline, desipramine and triflupromazine on adenosylmethionine decarboxylase purified from rat liver have been studied. The compounds caused competitive inhibition of the enzyme at 10(-5) - 10(-3) M concentrations. For chlorprothixene and triflupromazine the inhibition was linear, while the other drugs showed increasing, nonlinear inhibition at higher concentrations. Apparent Ki's for the compounds were between 6.8 X 10(-5) M (for chlorprothixene) and 6.4 X 10(-4) M (for desipramine). Inhibition of 50% under optimal assay conditions was achieved between drug concentrations of 1.3 X 10(-4) M (thioridazine) and 1.3 X 10(-3) M (imipramine).     

The Electrocardiogram and Ischemic Heart Disease in Aircraft Pilots

A review of the Royal Canadian Air Force electrocardiographic (ECG) program for selection of aircrew and detection of coronary disease in trained aircrew is presented. Twenty reported cases of death due to coronary disease in pilots while at the controls of an aircraft are reviewed. The use of routine electrocardiography in the selection of aircrew has proved to be of considerable value, particularly in view of the high cost of training. The ECG continues to be our most sensitive means of detecting asymptomatic coronary disease in aircrew personnel. It is apparent that from both the military and commercial standpoint the incidence of aircraft accidents due to coronary disease is extremely small. This is due in large part to the careful medical supervision of flying personnel including the routine use of electrocardiography in the assessment of flying fitness of aircrew.     

A Mathematical-Physical Model of the Genesis of the Electrocardiogram

A fundamental problem of cardiac electrophysiology is that of relating quantitatively the electrical activity within the heart to the complete timevarying potential distribution at the body surface. A new numerical method is described for the calculation of the surface potential on an irregularly shaped closed external surface due to an arbitrary source distribution in a medium containing regions of different conductivity, subject to the appropriate boundary conditions. The method is intended to provide an exact theoretical analysis of the experimental data acquired by A. M. Scher and others who have been mapping the pathways of ventricular depolarization in dogs and other animals. In anticipation of the above research program, a number of exploratory computations are reported. For example, the surface potential distribution has been calculated for a cylinder of human torso cross-section with a hemispherical dipole layer current source in approximate heart position and orientation and containing “lungs” of conductivity different from that of the surrounding medium. Under certain conditions, when lung-like inhomogeneities are introduced, a simple dipole source can generate a potential distribution having the multiple maxima and minima characteristic of higher multipole sources.     

Thioridazine Hydrochloride (Mellaril): Its Effect on the Electrocardiogram and a Report of Two Fatalities with Electrocardiographic Abnormalities

Twenty-eight electrocardiograms are presented which depict a quinidine-like effect of thioridazine on ventricular repolarization, in doses as low as 200 mg. a day. T waves have been found to flatten out and sometimes invert. Occasionally S-T segments have become convex and U waves have appeared.Case reports are presented of two patients who died while receiving large doses of thioridazine, 1500 and 3600 mg. daily, respectively. Terminal ECG patterns in each instance were those of heart block, alternating with episodes of ventricular tachycardia.The myocardium of one of the fatal cases revealed edema, increased vascularity, and some increase in connective tissue elements, along with fragmentation of muscle fibers. These changes were most pronounced in the interventricular septum.It is concluded that, because of the quinidine-like action of thioridazine on ventricular repolarization, caution is indicated when it is administered in large doses.     

Electrocardiogram of the reindeer, Rangifer tarandus tarandus

Electrocardiograms were recorded for 50 Finnish reindeer of age 1 day to 9 years, using standard and unipolar extremity leads in the frontal plane. The range of heart rate was 40-250 beats per minute. Atrial and ventricular depolarization times were 5-10 ms shorter in newborn calves than in other reindeer, and showed only minor variance with respect to heart rate. The duration of depolarization was dependant on heart rate, and was more rapid in young calves. A-V conduction time decreased with increasing heart rate. The mode of the QRS vector was 280-290 degrees, and the mode of the T vector 200-230 degrees in the older animals, but 100-120 degrees in young calves. The main deflection in the QRS complex was S in the leads II, III and aVF.R was dominant in aVL and I.