MUSCARINIC CHOLINERGIC, BUT NOT SEROTONINERGIC MEDIATION OF ARGININE VASOPRESSIN RESPONSE TO METOCLOPRAMIDE IN MAN

The possibility that metoclopramide (MCP) stimulates arginine vasopressin (AVP) secretion in man through a serotoninergic and/or a cholinergic muscarinic pathway was studied. Twenty normal male subjects were tested with MCP (10 mg in an i.v. bolus) alone or in the presence of the 5HT1 serotoninergic antagonist metergoline (10 mg/day p.o. in five divided doses for 4 days), the 5HT2 receptor blocker ketanserin (10 mg i.v. 5 min before MCP) (n = 10), the M1 and M2 muscarinic antagonist atropine (1.2 mg i.v. just before MCP administration) or the M1 muscarinic receptor blocker pirenzepine (40 mg i.v. 10 min before MCP) (n = 10). AVP doubled in response to MCP. the MCP-induced AVP rise did not change after metergoline, ketanserin or pirenzepine administration, whereas it was abolished by atropine. Additional experiments were performed in order to evaluate the effect of 1.2 mg atropine, given alone, on circulating AVP levels and whether the effect of atropine on the AVP response to MCP depends on the amount of the muscarinic antagonist (dose-response study). For these purposes, atropine was given alone to the same subjects previously tested with MCP plus atropine; furthermore, eight additional male subjects were tested with MCP plus atropine given in doses ranging from 0.8 to 1.4 mg. The results of these additional studies failed to show an effect of atropine alone on AVP secretion and demonstrated a dose-related inhibition of MCP-induced AVP rise by increasing atropine administration from 0.8 mg to 1.2 mg.(ABSTRACT TRUNCATED AT 250 WORDS)     

Scanning Electron Microscopy of Dermatofibromas

The three-dimensional morphology of six dermatofibromas was studied by scanning electron microscopy. Hypertrophic epidermal ridges covered with large keratinized cells overlay each dermal lesion. Small collagenous fibers in the tumors contrasted with the bundles of much larger collagenous fibers in the normal dermis peripheral to the lesions.     

Retrograde Pancreatography: New Contributions

The standard technic for pancreatography was modified by using a metallic guide wire in the proximal half of the cannula so as to regulate pressure independently from that applied manually.
The maximum pressure obtained by this method was measured in a polyethylene teflon cannula constructed to correspond to the Wirsung duct. Pressure was five times less when the guide wire was used. Our results in 33 patients correspond to experimental data. Only in 28% of our cases did the amylase rise slightly to a maximum of 290 Somogyi units.
Acinar opacification was attempted by adding Na₂CO₃ to a standard dye solution and was obtained in 20% of the cases (5 of 25). Maximum amylase elevation in this group was 263 Somogyi units.
No complications resulted from the pressure measurements during pancreatography.     

Treatment of Ventricular and Supraventricular Tachyarrhythmias by Transcutaneous Cardiac Pacing

The efficacy of noninvasive transcutaneous cardiac pacing (TCP) in the treatment of tachyarrhythmic events was tested in 24 patient: 14 with ventricular tachycardia, seven with supraventricular tachycardia and three with atrial flutter. Six (42.9%) ventricular tachycardias were interrupted: in two of the ten patients on whom underdrive pacing was attempted and in all four cases in which overdrive stimulation was possible. Five of the six supraventricular tachycardias utilizing an atrioventricular bypass tract were interrupted, while the TCP was unsuccessful on the only patient with atrioventricular nodal reentrant tachycardia. TCP failed to interrupt the arrhythmia in the three cases of atrial flutter. No clinically significant untoward effects (in particular tachycardia acceleration or ventricular fibrillation) were observed, except for a tolerable thumping sensation on the chest during pacing. In four patients, TCP effects on cardiac activation was evaluated by endocavitary recording: while the mean ventricular threshold was 70 mA, atrial capture was possible on only two patients at a current intensity of 140 and 150 mA. We consider our preliminary experience with TCP in the treatment of tachycardias encouraging. The technique was easily and rapidly usable and it was immediately successful in the majority of atrioventricular reentrant tachycardias and in a relevant percentage of ventricular tachycardias. In this latter setting TCP was mostly effective in the slower tachycardias where overdrive pacing was possible. A further experience with devices provided by higher pacing rates is warranted.     

Transcutaneous Cardiac Pacing: Evaluation of Cardiac Activation

ALTAMURA, G., ET AL.: Transcutaneous Cardiac Pacing: Evaluation of Cardiac Activation. The effects of transcutaneous cardiac pacing (TCP) on cardiac activation were evaluated by endocavitary recording (HRA, RVA) in eight patients, in order to test the possibility to obtain a simultaneous atrial and ventricular stimulation. The transcutaneous pacemaker used was the Pace Aid 52 (pacing rate 50–160 ppm, current output 10–150 mA, pulse width 20 sec). The two skin electrodes [surface area 50 cm²) were placed on the chest in anteroposterior position. Ventricular capture was observed in all patients [threshold = 74 ± 14 mA), simultaneous atrial capture was obtained in only four cases (threshold = 138 ± 25 mA). In conclusion, our data show that four-chamber simultaneous stimulation by TCP is possible, but only with pacing energies much higher than those usually required to capture the ventricle. The ability of TCP to simultaneously pace the atria and ventricles, though not relevant in the emergency cardiac stimulation for symptomatic severe bradyarrhythmias, could be useful in the treatment of reentrant supraventricular tachycardias.     

Scanning Electron Microscopy of Yeasts in Seborrheic Keratoses

Lesions of seborrheic keratoses were studied by scanning electrom microscopy. Numerous yeasts were present on the karatinized cells and hairs associated with the lesions. Surfaces of some yeasts were smooth and others were ruffled. The ruffles suggested the presence of a glycocalyx. The yeasts exhibited the morphological features of Pityrosporum ovale.     

Transthoracic DC Shock May Represent a Serious Hazard in Pacemaker Dependent Patients

External defibrillation is widely used for the termination of various atrial and ventricular tachyarrhythmias, including pacemaker patients. Our study was intended to evaluate the effects of DC shocks in 36 patients with unipolar pacemakers implanted in the right pectoral region (25 DDD, 10 VVI, 3 AAI). The shocks were delivered with paddles on the anterior surface of the thorax, as far as possible away from the pacemaker. The pacing output was programmed at 0.5 msec and 5 V (25 patients), 4 V (1 patient), and 2.5 V (10 patients). Transient loss of capture occurred in 18 patients (50%). These patients, compared with those without capture failure, received higher peak and cumulative shock energies, respectively, 216 ± 99 versus 123 ± 50 joules (P < 0.002) and 352 ± 62 versus 147 ± 98 joules (P < 0.004) and had a lower pacemaker pulse amplitude (4.0 ± 1.2 vs 4.6 ± 1.0 V, P = 0.11). Failure to capture lasted from 5 seconds to 30 minutes (mean 157 sec). In 15 patients the ventricular stimulation threshold was measured before and serially after cardioversion. A six-fold threshold increase was observed 3 minutes after the shock (P < 0.004) with gradual recovery to nearly baseline values at 24 hours. Transient sensing failure occurred in 7 of the 17 patients in whom it could be evaluated (41%). Furthermore, three cases of shock induced pacemaker malfunctions were observed requiring replacement of the stimulator in two patients. In conclusion, the incidence of loss of capture in pacemaker patients subjected to electrical cardioversion/defibrillation is high. The phenomenon is due to an abrupt rise in stimulation threshold, caused by the electrical shock, and may represent a serious hazard in pacemaker dependent patients. The risk of pacing failure could be reduced by utilizing low shock energies when possible, and by programming the pacemaker at its maximal output before cardioversion.     

Endoscopic, Radiologic and Manometric Correlation in Small Sliding Hiatal Hernia

Of the three methods employed, endoscopy seems to be the most accurate since it permits identification of both anatomical structures and serves as a basis for interpretation of radiology and manometry. Cardial incisura was the easiest and most constantly identifiable structure by the three methods. It must be considered as the union between esophagus and stomach. In small sliding hiatal hernia, the cardial incisura remains below the diaphragm and the gastric mucosa slides up into the chest, resulting in a partial prolapse (hiatal hernia of sliding mucosa). This concept would clarify the difference in interpretation of the most commonly used procedures in diagnosis of sliding hiatal hernia.     

Low Strength Anthralin in Psoriasis

Anthralin in low concentrations (0.01%--0.03%) was applied in an ointment form once per day in the hospital to 130 psoriasis patients. The treatment program included also the use of UVB light, emollients and bath oil and an antihistamine. Clearing of psoriasis was achieved in all patients in an average time of 4 weeks. The involution of the lesions was carefully studied by correlated clinical observations, light microscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Striking healing of the holes in the stratum corneum and of the gaps in the basement membrane occurred. Low strength anthralin, in addition to its effectiveness, did not produce irritation, staining or side-effects.