Behavioural Subsensitivity Induced by Long-term Administration of a Low Dose of Haloperidol to Rats

This study examines the effects on open-field and stereotyped behaviour of rats of abrupt withdrawal from repeated treatment with a low (0.03 mg kg^?1) dose of haloperidol. Single administration of this low dose of haloperidol significantly increased open-field locomotion without modifying apomorphine (0.5 or 2.0 mg kg^?1)-induced stereotyped behaviour. Forty-eight hours after abrupt withdrawal from 0.03 mg kg^?1 haloperidol (twice daily for 15 days) a significant decrease in locomotion frequency was observed, but no change was observed in apomorphine-induced stereotypy. Our results suggest that dopamine autoreceptor supersensitivity might be evaluated in a behavioural situation of absence of postsynaptic dopamine receptor supersensitivity.     

OPEN RANDOMIZED COMPARISON OE ITRACONAZOLE VERSUS TERBINAEINE IN ONYCHOMYCOSIS

Background. Onychomycoses are among the most frequent nail diseases. The principal agents are dermatophytes, Itraconazole and terbinafine are two effective and systemic antimycotics. Previous trials have shown, that treatment schedules with effective concentrations for 3 months cause drug deposits in nail plates that persist 6 months after the end of the treatment. Methods. A comparative, open, prospective study was carried out with random assignment of patients. The first group included 27 patients under treatment with 200 mg of itraconazole once daily for 3 months. The second group included 26 patients treated with 250 mg of terbinafine for 3 months. Both series of patients were followed for 6 additional months. Results. Both groups were similar in age, sex, and history of onychomycosis, Trichophyton rubrum was the main isolated agent in all patients. The percentage of diseased nails was similar in both groups affecting predominantly the first toenail. Treatment was highly effective and differences between groups were not significant. The rate of adverse events was 21% in the itraconazole group and 47% in the terbinafine group. Conclusions. Itraconazole and terbinafine are two drugs of choice in dermatophytic onychomycosis.     

ROLE OF ALCOHOLIC BEVERAGES IN ESSENTIAL HYPERTENSIVE PATIENTS

To evaluate the importance of alcohol and other environmentalfactors in essential hypertensives, we conducted a cross-sectionalstudy on 627 patients (322 women, 305 men) subdivided in foursubgroups according to sex and presence or absence of drug therapy,to evaluate differences due to drugs and changes in life style.Multiple regression analyses were run where systolic and diastolicblood pressures were considered as separate dependent variableswith the following independent variables: age, body mass index,physical activity, alcohol and coffee consumption, smoking,educational level; considered as continuous or categorical variables.Eighty-eight per cent of all patients showed a moderate-lowalcohol intake (1–50 g/day); wine was the preferred beverage.We found a negative independent relationship between mild/moderatealcohol consumption levels and systolic blood pressure in untreatedmen and untreated women, and no relationship between alcoholand diastolic blood pressure in all subgroups considered. Bodymass index and age were positively associated with both systolicand diastolic blood pressure. Our data suggest that mild tomoderate alcohol consumption does not affect blood pressurecontrol in either treated or untreated hypertensive patients.     

Mid-systolic Click and Echocardiographic Evidence of Mitral Valve Prolapse During Electrical Pacing

A mid-systolic click was present in a patient during three years of follow-up after implantation of a permanent transvenous pacemaker. Echocardiography revealed posterior motion of the anterior leaflet which resembled mitral valve prolapse. Both the click and echocardiographic evidence of prolapse disappeared simultaneously with resumption of sinus rhythm and during supraventricular tachyarrhythmias. With spontaneous change in the position of the electrode three years after initial implantation, both the click and the posterior motion of the mitral valve disappeared. The association of mitral valve prolapse with electrical pacing is most unusual and appears to have a distinct pathophysiological mechanism. (PACE, Vol. 4, November-December, 1981)     

Mathematical Descriptions of AV Nodal Function Curves in Dogs

Thirty-four anaestheized mongrel dogs subjected to thoracotomy were used to study AV node conduction during atrial pacing at increasing rates. Eplcardial atrial electrodes were used, together with endocavitary recordings of His bundle electrogram. An analysis was made of the repercussions involved in using four different mathematical functions describing nodal conduction; three were nonlinear (exponential and hyperbolic A and B) and one linear. In the case of the first three, the consequences of using a direct nonlinear data-fitting procedure or an indirect procedure by linear transformations of the functions were studied. The exponential and hyperbolic B functions provided the least mean squared residual in quantifying nodal conduction (8.6 ± 10.8 ms² and 10.8 ± 13.9 ms², respectively). The use of nonlinear function transformation into a linear representation caused Joss of precision in the fit to the data in the case of the exponential function (18.3 ± 22.2 ms² versus 8.Q ± 10.8 ms², p < 0.01] and, to a lesser extent, in the case of the hyperbolic B function [12.5 ± 16.4 ms² versus 10.8 ± 13.9 ms², P < 0.05).     

Effects of Hydrophilic and Lipophilic β-Blockers on Heart Rate Variability and Baroreflex Sensitivity in Normal Subjects

To evaluate the effect of a hydrophilic and a lipophilic β- blocker on the autonomic nervous system, 20 normal subjects were studied under baseline conditions and 7 days after being randomly assigned to metoprolol (200 mg/day), nadolol (80 mg/day), and placebo. Under each condition, the time-domain parameters were analyzed by means of 24-hour ECG monitoring and the frequency-domain parameters by means of the autoregressive method using 10-minute ECGs during rest, controlled respiration, and after a head-up tilt test. The alpha index (the gain in the relationship between the RR period and systolic arterial pressure variability) was also calculated. Both nadolol and metoprolol significantly increased all of the time-domain parameters except the standard deviation of the RR intervals; they also modified the frequency-domain parameters. Both blunted the significant reduction in the high frequency (HF) component and alpha index during tilt. In normal subjects, hydrophilic and lipophilic β-blockers similarly modify the time- and frequency-domain parameters that are particularly evident when high sympathetic tone is present (during daytime and tilt). The value of the alpha index was increased by both β-blockers in the HF, but not in the low frequency band; this difference might be due to the fact that the former is a measure of the vagal component of the baroreflex control and the latter a measure of the sympathethic component. The effects of hydrophilic and lipophilic β-blockers on the time- and frequency-domain parameters of heart rate variability are similar.