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Biomedical subjects

J B Pace

Publications and source records attributed to J B Pace.

At least 19 recordsLinked to original sources
PubMed1982

Cardiovascular effects of thoracic afferent nerve stimulation in conscious dogs.

Afferent stimulation of a severed thoracic autonomic nerve in 18 conscious dogs produced in 13 instances hypertension and in 5 instances hypotension. Reflex hypertension was usually accompanied by augmented atrial and ventricular force of contraction. The hypertension could be maintained for over 5-min duration by constant stimulation. Inotropic changes accompanying this hypertension were accentuated following atropine administration and abolished by propranolol. Blood pressure changes following atropinization were initially augmented. On the other hand reflex hypotension was accompanied by bradycardia and decreased atrial contractility. These changes were essentially abolished by atropine. Afferent nerve stimulation with frequencies as low as 1 Hz initiated reflex changes. Maximal responses were obtained by stimulation frequencies of 10-15 Hz. It is concluded that significant and relatively sustained cardiovascular reflexes can be generated by stimulation of cardiac afferent nerves in conscious dogs.

Animals↗
PubMed1980

Low back pain.

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Back Pain↗
PubMed1977

Influence of coronary occlusion on pulmonary vascular resistance in anesthetized dogs.

The effects of occlusion of the left anterior descending coronary artery on pulmonary hemodynamics and calculated pulmonary vascular resistance were measured in 17 open chest dogs anesthetized with chloralose. Coronary occlusion was associated with a slight but insignificant increase in mean pulmonary arterial pressure together with a significant elevation in mean left atrial pressure (P less than 0.01) and a significant reduction in mean pulmonary flow (P less than 0.01). Calculated pulmonary vascular resistance was significantly reduced during occlusion (P less than 0.01). The reduction in resistance was associated with elevated mean left atrial pressure and therefore reflected passive distension of pulmonary vessels secondary to suppressed left ventricular function. In contrast, coronary occlusion after vagotomy was not associated with a significant reduction in pulmonary vascular resistance, and in six experiments the decrease in resistance was converted to an increase. It is concluded that, before vagotomy, pulmonary hemodynamics during coronary occlusion are primarily affected through passive vessel distension whereas, after vagotomy tonic suppression of sympathetic activity is interrupted, thereby allowing enhancement of sympathetic vasoconstrictor activity to the pulmonary vascular bed and producing an increase in calculated resistance.

Animals↗
PubMed1977

Psychophysiology of pain: diagnostic and therapeutic implications.

Pain problems occupy muct of the time and therapeutic efforts of physicians. Nonmedical practitioners and cultists have likewise attracted many people seeking pain relief. In many cases the cultists seem to do as well as the ethical practitioner. A realistic view of pain takes into account the significance of the pain to the individual, the degree of anxiety and/or depression that contributes to the aggravation and prepetuation of the pain, and finally the manipulative and defensive value that the pain may have to the individual. A purely mechanistic approach which would attempt to distinguish "real pain", ie, pain associated with a demonstrable lesion, and "imagined pain" will prove counterproductive. Likewise accusations of consciously pretended pain or malingering tend to be nontherapeutic. A sound therapeutic approach is to regard all pain as real, realizing that the pain of depression may be the most unendurable type of pain. Major psychotropic drugs for relief of anxiety and for treatment of depression have appplication in the management of selected pain problems.

Anti-Inflammatory Agents↗
PubMed1976

Piriform syndrome.

Among a variety of deep muscle trigger points, the piriform muscle trigger point is selected for individual scrutiny. This seems fully justified by the great potential for confusing this entity with discogenic disease and consequently having unnecessary surgical procedures carried out.The diagnosis can be made from findings on simple physical diagnostic tests and an appropriate history. Low back and hip pain with pain radiating down the back of the leg should suggest piriform syndrome as part of the differential diagnosis. This is especially true if a female patient has complaint of dyspareunia. Pain and weakness on resisted abduction-external rotation of the thigh is a sign of piriform syndrome. This is confirmed by tenderness and reproduction of the patient's complaints by digital pressure over the belly of the piriform muscle, completing the diagnostic criteria. Local injection of the muscle belly is curative. There are no laboratory or x-ray findings leading to a diagnosis.

Back Pain↗
PubMed1975

Pressure-flow relations in the vessels of the canine aortic arch.

Simultaneous measurements of pressure and flow have been made in the vessels of the aortic arch in chloralose-anesthetized dogs under three conditions; control, cardiac sympathetic (SS), and vagal nerve stimulation (VS). The specific sites studied include ascending aorta (AA), descending thoracic aorta (DTA), and brachiocephalic (BCA), left subclavian (LSC), and common carotid arteries (CA). Recorded data were analyzed by Fourier series methods and were used to calculate vascular impedance spectra, pressure and flow propagation characteristics, and hydraulic power. The distribution of cardiac output was found to be 70% to DTA, 22.2% to BCA, and 6.5% to LSC. The fraction of cardiac output to the BCA, LSC, and CA was increased by both SS and VS. The hydraulic power was distributed to the arch vessels nearly the same as the cardiac output. Hydraulic power dissipated in the arch vessels averaged 6% of the total AA hydraulic power and was increased by SS and decreased by VS. The results suggest that viscous losses in the arterial walls represent a considerable portion of the power dissipation. A similarity found in the vascular impedance spectra at the various sites for all three conditions was also observed for the transmission characteristics of pressure and flow harmonics between the sites. The results suggest that major reflections do not occur in the proximal aorta.

Animals↗