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Biomedical subjects

S Gottlieb

Publications and source records attributed to S Gottlieb.

At least 289 records · Page 16Linked to original sources
PubMed1984

The distribution of afferent neurones in the mesencephalic nucleus of the fifth nerve in the cat.

The objective of this study was to examine anatomically the distribution of afferent neurones in the mesencephalic nucleus of the fifth nerve (Mes V). HRP was applied, in separate experiments, to the inferior alveolar, infraorbital, and masseter nerves, and injected into the masseter muscle and periodontal ligament. Following application of HRP to the masseter muscle and masseter nerve, labelled cells were found in the ipsilateral motor nucleus of the fifth nerve and in the ipsilateral Mes V. Labelled cells in Mes V, identified as belonging to proprioceptor afferents from jaw-closing muscles, were distributed throughout the full extent of the nucleus. Following application of HRP to the inferior alveolar nerve, infraorbital nerve, and periodontal ligament, labelled cells were found in the ipsilateral trigeminal ganglion and Mes V, and the latter identified as belonging to periodontal receptor afferents. In contrast to the distribution of spindle afferent somata, they were restricted to the caudal region of Mes V. The differential distribution of afferent neurones within Mes V demonstrated in this study confirms previous electrophysiological findings, and its significance is considered.

Animals↗
PubMed1984

Early right atrial pacing after myocardial infarction. I. Comparison with early treadmill testing.

Right atrial (RA) pacing and modified treadmill testing (TT) were performed in 111 patients recovering from acute myocardial infarction (MI) before hospital discharge to determine whether ischemic responses are more common with RA pacing than with TT and whether the prognosis could be better determined by the results of 1 test compared with the other. Patients with predischarge congestive heart failure, chest pain, physical disability or age older than 70 years were excluded. Ischemic responses were significantly more frequent during RA pacing than during TT (41% vs 34%, p = 0.02). The results of the 2 tests were concordant in 102 patients (92%): Both were positive in 37 and both negative in 65. In 8 patients, results of RA pacing were positive and results of TT were negative; only 1 patient had positive TT and negative RA pacing responses. The higher percentage of positive responses during RA pacing than during TT can be attributed to the significantly higher pressure-rate product achieved during pacing (18,773 vs 16,831 mm Hg/min, p less than 0.001). The ischemic threshold, defined as the pressure-rate product at which an ischemic change was first noted in a particular patient, was almost identical in both tests. During a mean follow-up period of 16 months, 10 patients had recurrent MI; 8 had positive predischarge RA pacing but only 5 had positive TT responses (p = 0.008). Six patients died; in 3 RA pacing responses were positive and in 2 TT responses were positive.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Early right atrial pacing after myocardial infarction. II. Results in 77 patients with predischarge angina pectoris, congestive heart failure, or age older than 70 years.

Seventy-seven consecutive postinfarction patients who had either predischarge angina pectoris or congestive heart failure, or who were older than 70 years of age, underwent right atrial (RA) pacing before hospital discharge. In 60% of these patients, ischemic changes developed during RA pacing; this high yield of positive response indicates advanced coronary arterial disease. During a mean follow-up of 15 months, these patients had a high mortality rate (18%) and a reinfarction rate of 9%. RA pacing separated this a priori high-risk group into lower- and higher-risk subsets. Of the 46 patients with a positive RA pacing response, 6 had reinfarction, while none of the 31 patients with a negative RA pacing response had reinfarction (p = 0.04); 10 of the 14 cardiac deaths were among the patients who had positive RA pacing responses at discharge (p = not significant). Thus, of the 20 major cardiac events, 16 occurred among those with positive RA pacing responses (p less than 0.05). Predischarge clinical symptoms, however, were not good predictors of subsequent major cardiac events. We conclude that RA pacing can be safely performed even in high-risk and elderly patients and a positive response can identify those who have a poorer prognosis. Therefore, for postinfarction patients who, according to the prevailing criteria, are excluded from treadmill testing, we advocate the use of RA pacing.

Adult↗
PubMed1983

Prazosin therapy for refractory variant angina.

The selective alpha, blocker prazosin was used to abolish Prinzmetal's variant angina in six patients. All had had an acute transmural myocardial infarction, after which the anginal attacks with transient ST segment elevation developed, and three of them had already suffered from variant angina prior to the infarction. Therapeutic trials with high doses of nifedipine, verapamil, nitrates, beta blockers, and (in one case) phenoxybenzamine were ineffective in all six patients. Prazosin, 8 to 30 mg/day combined with low-dose nitrates or nifedipine completely abolished the attacks in four patients, markedly reduced their frequency and intensity in one patient, and had to be stopped in the sixth one because of hypotension and dizziness. Except for this last patient, the drug was well tolerated by all the others, and no changes in blood pressure were observed. In four patients discontinuation or reduction of prazosin resulted in exacerbation of symptoms, but its renewal was followed by disappearance of the attacks. Since the mean follow-up period in this study was 4 to 6 months, further evaluation appears necessary concerning the long-term effects of this drug in Prinzmetal's variant angina.

Aged↗
PubMed1983

The 4-6 HZ tremor during sustained contraction in normal human subjects.

Continuous elevation of the middle finger for 15-60 min gave rise to modulation of the e.m.g. at 4-6 Hz. A marked peak (50-150% of the amplitude of the coexisting 8-12 Hz peak) at 4-6 Hz was produced in sixteen out of twenty-one subjects. The 8-12 Hz peak was also enhanced (2-14 times with respect to its initial amplitude in eighteen subjects) during the course of the prolonged contraction but its frequency did not change. The 4-6 Hz and the 8-12 Hz peaks were present simultaneously; it is concluded that the two phenomena are separate entities. A step-function mechanical perturbation of the finger generates, time-locked to the stimulus, a train of waves at the frequency of the slow tremor, which can be abolished by local ischaemia. It is proposed that this slow tremor is due to an oscillatory process, possibly involving the reflex arc, but entailing a longer neuronal delay than that responsible for 8-12 Hz tremor.

Adolescent↗
PubMed1983

Interpretation of fusimotor activity in cat masseter nerve during reflex jaw movements.

Simultaneous recordings were made from fusimotor axons in the central ends of filaments of the masseter nerve, and from masseter and temporalis spindle afferents in the mesencephalic nucleus of the fifth cranial nerve in lightly anaesthetized cats. Fusimotor and alpha-motor units in the masseter nerve were differentiated on the basis of their response to passive ramp and hold stretches applied to the jaw. Spindle afferents were identified as primary or secondary according to their dynamic index after administration of suxamethonium. The activity of a given fusimotor unit during reflex movements of the jaw followed one of two distinct patterns: so-called 'tonic' units showed a general increase in activity during a movement, without detailed relation to lengthening or shortening, while 'modulated' units displayed a striking modulation of their activity with shortening, and were usually silent during subsequent lengthening. Comparison of the simultaneously recorded fusimotor and spindle afferent activity suggests that modulated units may be representative of a population of static fusimotor neurones, and tonic units of a population of dynamic fusimotor neurones. In these lightly anaesthetized animals, both primary and secondary spindle afferents showed increased firing during muscle shortening as well as during lengthening. This increase during shortening is not usually seen in conscious animals and reasons are given for the view that it is due to greater depression of alpha-motor activity than of static fusimotor activity during anaesthesia. The results are discussed in relation to the theories of 'alpha-gamma co-activation' and of 'servo-assistance'; and it is suggested that static fusimotor neurones provide a 'temporal template' of the intended movement, while dynamic fusimotor neurones set the required dynamic sensitivity to deviations from the intended movement pattern.

Action Potentials↗
PubMed1983

Exercise-induced S-T segment elevation in variant angina.

3 patients with co-existing effort angina and Prinzmetal's variant angina are described, who had also 'atypical' manifestations of variant angina, i.e. chest pain and S-T segment elevation also during treadmill exercise testing. Because of these unusual manifestations the proper diagnosis was delayed and the patients continued with inappropriate therapy (propranolol and only low-dose nitrates). After the correct diagnosis of variant angina with 'atypical' manifestations was made, application of high-dose nitrates and nifedipine resulted in complete relief of symptoms. Repeat treadmill testing during this therapy did not provoke attacks of chest pain with S-T elevation.

Angina Pectoris, Variant↗
PubMed1982

Comparison of right atrial pacing soon after myocardial infarction with treadmill testing 6 months later.

Seventy-four patients recovering from acute myocardial infarction underwent right atrial pacing before hospital discharge, and treadmill exercise testing 6 months later. The early right atrial pacing test was positive in 32 patients (43 percent) and the late treadmill test was positive in 32 patients (42 percent). The results of the two tests were concordant in 77 percent of the patients, 23 with an ischemic response and 34 with a normal response on both tests. In nine patients a positive right atrial pacing test was followed by a negative treadmill test, and in eight patients a negative pacing test was followed by a positive treadmill test. A positive right atrial pacing test at hospital discharge had an 81.0 percent predictive accuracy for a positive late treadmill test; chest pain, congestive heart failure or increased cardiothoracic ratio at discharge had a predictive value of only 52.9, 42.8 and 42.8 percent, respectively. Both the early right atrial pacing test and the late treadmill test were positive in a significantly higher proportion of patients with inferior or subendocardial infarction than of patients with anterior myocardial infarction. During early right atrial pacing the mean maximal heart rate achieved was higher than that during late treadmill testing (148 versus 133 beats/min) and the mean systolic blood pressure was lower (137 versus 162 mm Hg), but the pressure-rate product was similar on the two tests (20,282 versus 21,455 mm Hg/min). This finding may explain the similar frequency of ischemic responses to the two tests. These results indicate that the response to right atrial pacing soon after myocardial infarction is a good predictor for the presence or absence of an ischemic response to treadmill testing 6 months later. Thus, early right atrial pacing at the time of hospital discharge may be used to determine the pace of rehabilitation and short-term prognosis.

Adult↗
PubMed1982

Atypical ventricular tachycardia (torsade de pointes) induced by amiodarone: arrhythmia previously induced by quinidine and disopyramide.

A 44-year-old woman is described in whom amiodarone, disopyramide, and quinidine, administered alone separately, induced atypical ventricular tachycardia (AVT, torsade de pointes). Following a closed mitral valvotomy, she received quinidine, 1.2 g/day, without interruption for 17 years. Because of a recurrence of paroxysmal atrial fibrillation, the dose of the drug was increased to 1.4 g/day; 24 hours later AVT with syncope developed but responded promptly to atropine. Two years later, 24 hours following an increase in the dose of disopyramide from 300 to 600 mg/day, AVT with syncope occurred; isoproterenol abolished the arrhythmia instantly. Amiodarone was the third drug to induce AVT in this patient; she received 200 mg/day six days per week for six months. The dose was subsequently increased to 200 and 400 mg/day on alternate days, six days per week, and two months later AVT occurred. That time the only effective treatment was ventricular pacing.

Adult↗
PubMed1981

Etiology, warning signs and therapy of torsade de pointes. A study of 10 patients.

Torsade de pointes, also called atypical ventricular tachycardia (AVT), was diagnosed in 10 patients, nine on antiarrhythmic therapy and one with acute central nervous system damage. Four patients received quinidine and five disopyramide, either alone or in combination with amiodarone. AVT was dose-dependent in some, but in others, it started shortly after initiation of drug therapy (idiosyncrasy). All patients had QT prolongation longer than 0.60 second immediately before the onset of AVT. This measurement appeared to be a more sensitive predictor of the development of AVT than QTc prolongation or QRS widening. All patients also showed bradycardia before AVT onset. After therapy, the QT immediately decreased, while QTc and QRS remained prolonged for longer periods. Isoproterenol was effective in five of seven patients, but was contraindicated in two others. Ventricular pacing was used in four patients, including the two who did not respond to isoproterenol, and this abolished AVT promptly. Isoproterenol or pacing appear to be the therapy of choice for AVT, while the conventional drugs used to treat the usual form of ventricular tachycardia are not only ineffective, but even contraindicated.

Adult↗
PubMed1981

Disopyramide-induced Torsade de Pointes.

Recurrent ventricular tachycardia (torsade de pointes) is a serious and sometimes fatal arrhythmia occurring usually with quinidine therapy. Four patients experienced ventricular tachycardia after receiving conventional doses of disopyramide phosphate (600 mg/day) for recurrent atrial fibrillation-two of them in combination with amiodarone hydrochloride. Isoproterenol hydrochloride infusion was effective in three patients, while ventricular pacing promptly abolished ventricular ectopic beats and the ventricular tachycardia in the fourth patient. Torsade de pointes is more likely to occur in patients with severe repolarization delay and sinus bradycardia or atrioventricular block, and its appearance in four patients within a period of nine months after the introduction of disopyramide treatment in our service raises the possibility that this is not a rare complication of this drug, especially if used in combination with other QT interval-prolonging agents.

Aged↗