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Biomedical subjects

J M Sullivan

Publications and source records attributed to J M Sullivan.

At least 145 records · Page 8Linked to original sources
PubMed1979

The orthograde labeling of postganglionic sympathetic cardiac nerves in the dog and cat as demonstrated by autoradiography.

Previous functional and anatomical techniques have characterized the cardiac nerves and plexuses. They cannot, however, determine the course of fibers arising from a specific ganglion. This study has found that the intraaxonal orthograde labeling of axons can be used to determine the course of postganglionic sympathetic cardiac fibers in the dog and cat. The canine left caudal cervical ganglion and the feline right stellate ganglion were exposed through appropriate thoracotomies. Each ganglion received multiple injections of tritiated leucine (500 muCi/animal). Following a 3--14-day survival period the anesthetized animals were sacrificed by vascular perfusion. The injected ganglia, extracardiac nerves and selected portions of the heart were processed for autoradiography. Autoradiographs from the dog demonstrated labeled postganglionic sympathetic nerves in the extracardiac plexus, left atrial epicardium and the epicardium beneath the coronary sulcus. Labeled nerves in the cat heart were found within the epicardial layers and associated with blood vessels in the left ventricular myocardium. Neither myelinated fibers traveling through the injection site nor intrinsic cardiac ganglion cells were labeled, although the latter were often closely approximated to heavily labeled fibers.

Animals↗
PubMed1979

The effect of diet on echocardiographic left ventricular dimensions in normal man.

The effect of dietary sodium and potassium on echocardiographic left ventricular dimensions was studied in normal subjects. In 10 subjects, left ventricular end diastolic volume was found to be 18.8 greater, and systolic volume 17.1% higher with zoo mEq sodium diet than on a 1Omeq sodium diet (P less than 0.025). While receiving an ad libitum diet, the subjects were found to have an end diastolic volume of 107.9 +/- 6.4 ml SE and an end systolic volume of 45.2 +/- 2.7 ml SE. During sodium depletion, values fell to 101.3 +/- 5.7 ml SE and 38.6 +/- 2.9 ml SE, respectively, then on a high sodium diet rose to 120.3 +/- 7.0 ml SE and 45.2 +/- 2.7 ml SE, respectively. Heart rate fell during sodium repletion by 4.2% (P less than 0.05) while mean arterial blood pressure, cardiac output and peripheral vascular resistance did not change significantly. In contrast, seven subjects consuming a diet containing 25 and 200 mEq potassium in seqeucne, the sodium intake remaining constant, did not display significant changes in cardiac dimension, heart rate, blood pressure, cardiac output, or vascular resistance. It is concluded that dietary sodium significantly effects the size of a nonfailing left ventricle, an effect that must be considered when single or sequential echocardiograms are interpreted.

Blood Pressure↗
PubMed1979

beta-Adrenoceptor-blocking agents and the kidney: effect of nadolol and propranolol on the renal circulation.

1 Nadolol was administered intravenously to five hypertensive patients and three healthy volunteers in balance on a 10 mEq sodium intake. 2 Nadolol (0.3-10.0 micrograms/kg) induced a significant, dose-related increase in renal blood flow, measured with radioxenon, with a maximum increase of 72 +/- 4 ml/100g/min (26%) at 3.0 micrograms/kg. 3 Heart rate and plasma renin activity decreased significantly over the same dose range. 4 The renal vascular response to nadolol contrasts sharply with those found with other beta-adrenoceptor-blocking agents. 5 The magnitude of the increase in renal blood flow, its time-course and the parallel fall in plasma renin activity raise the possibility that the renal vasodilation reflects the reversal of angiotensin's influence on the renal arterial bed.

Adrenergic beta-Antagonists↗
PubMed1979

Short-term therapy of severe hypertension. Hemodynamic correlates of the antihypertensive response in man.

Ten severely hypertensive patients were randomized into five treatment groups: vasodilators; vasodilators plus diuretics; sympatholytics; sympatholytics plus diuretics; and sympatholytics, diuretics, and vasodialtors. Cardiac index was measured daily by echocardiography, and total peripheral resistance (TPR) calculated. Plasma renin activity (PRA) and creatinine clearance (CCR) were measured every other day. There was no difference in antihypertensive response. Seven patients, whose initial TPR was high, responded to treatment with a fall in TPR, regardless of regimen. Three patients with a high pretreatment cardiac index responded with a fall in cardiac index. Changes in TPR or cardiac index were not related to changes in CCR. There was no correlation between PRA and either blood pressure or TPR. It is concluded that the pretreatment hemodynamic status of severely hypertensive patients is the major determinant of the hemodynamic response to antihypertensive therapy.

Adolescent↗
PubMed1978

SQ 20,881: effect on eclamptic--pre-eclamptic women with postpartum hypertension.

The renin-angiotensin system has been implicated in the genesis of pre-eclampsia. To avoid fetal toxicity, five women were studied who developed hypertension, proteinuria, and edema in the last trimester of pregnancy and whose BP elevation persisted immediately postpartum. At about 6 hours after delivery the CE enzyme inhibitor (SQ 20,881) was given in incremental doses ranging from 0.25 to 3.0 mg. per kilogram intravenously, before and after diuresis with furosemide, 40 mg. intravenously. BP was measure every 2 minutes and PRA and angiotensin II concentration before treatment, 30 minutes after 0.25 to 0.30 mg. per kilogram, and 30 minutes after 2.0 to 3.0 mg. per kilogram. Echocardiographic assessment of CI and PVR was performed before treatment and after a maximum dose in three patients. Before diuresis, CE blockade had no effect on heart rate, BP, CI, PVR, or PRA, regardless of whether the patient was in positive or negative fluid balance or was sodium loaded or restricted over the preceding 24 hours. Angiotensin II fell by 77 and 10 per cent, respectively, after 0.25 mg. per kilogram was given to two patients, but rose slightly in the other three patients, then fell an average of 46 per cent after 1.0 to 3.0 mg. per kilogram were given. After diuresis, 1.0 mg. per kilogram resulted in a 24 per cent fall in BP which persisted for 3 hours in two patients and a 14 per cent fall which lasted for 30 minutes after 1.0 or 3.0 mg. per kilogram in a third patient. It is concluded that the BP elevation which persists after delivery in certain patients with pre-eclampsia is not angiotensin II dependent.

Adolescent↗
PubMed1977

Myocardial renin-angiotensin extraction in man.

Renin activity, renin substrate, and angiotensin II concentration were measured in the aortic and coronary sinus blood of 14 patients. There was a significant gradient for angiotensin II only. The gradient was diminished in areas of ischaemic myocardium. The study suggests that angiotensin II is partially bound, extracted, or destroyed in the coronary circulation of man.

Adult↗
PubMed1977

Transient hypotensive effect of phenytoin in man.

Phenytoin or an identically appearing placebo was administered in a double-blind fashion to 20 patients with mild essential hypertension. A significant fall in supine systolic blood pressure was noted 30 minutes to 1 hour after the oral administration of 100 mg phenytoin. No significant antihypertensive effect was observed after the patients had received 100 mg phenytoin every 8 hours for two weeks. Phenytoin had no effect on the diastolic blood pressure. It is concluded that the previously described hypotensive effect of phenytoin is a transient phenomenon which is of no therapeutic benefit in the long-term management of patients with essential hypertension.

Adult↗
PubMed1976

beta-adrenergic blockade in essential hypertension: reduced renin release despite renal vasoconstriction.

The acute effects of small doses of intravenous propranolol on renin release and on circulatory dynamics were studied at the time of renal arteriography in 12 persons with essential hypertension. All of the subjects had a normal peripheral renin response to chronic sodium depletion and all had normal renal function. Seven subjects received a 10-mEq sodium diet. At the time of arteriography, arterial blood pressure, pulse rate, cardiac output, renal blood flow, and arterial and renal venous renin activity were measured before and 6-20 minutes after the intravenous administration of propranolol (9-18 mjg/kg). Average renin secretion rate in the salt-depleted subjects fell from 367 +/- 80 (SEM) U/ml per 100 g/min to 122 +/- 51 U/ml per 100 g (P=0.03) and renal plasma flow fell from 189 to 155 ml/min per 100 g (P = 0.018). We also found that in the salt-loaded subjects, renal plasma flow fell from 213 to 184 ml/min per 100 g (P = 0.025), whereas renin secretion did not change significantly in either group. We conclude that propranolol rapidly blocks renin release despite circulatory changes which ordinarily constitute a stimulus for renin secretion, i.e., renal vasoconstriction and reduced renal blood flow.

Adult↗
PubMed1976

Angiotensin II stimulation of 5'-adenylic acid deaminase.

Angiotensin II has been found to stimulate 5'-adenylic acid deaminase from rabbit skeletal muscle. Stimulation was discernible around 10(-9) M and peak stimulation of about threefold was seen at 10(-7) M, concentrations approximating those required for stimulation of vascular smooth muscle or adrenal glomerulosa cells. Higher concentrations produced less stimulation. Adenosine triphosphate stimulated to the same degree, but a concentration of 10(-5) M was required for maximum stimulation, while maximum stimulation with sodium or potassium required 0.5 M and 0.75 M, respectively. Although the physiologic significance of these observations has not been established, these data suggest an intracellular role for angiotensin II.

AMP Deaminase↗
PubMed1976

The influence of induced abortion on Taiwanese fertility.

Data on the outcomes of more than 15,000 pregnancies originating between May 1966 and February 1969 were analyzed. The accuracy of the data was evaluated, rates of induced abortion and stillbirth were reported, and the demographic effect of induced abortion was estimated. The demographic effect was defined as the percentage increase in fertility that would have occurred in the absence of induced abortion, assuming no compensating change in alternative fertility control practices. Our principal findings were as follows: 1. We were unable to determine the completeness with which induced abortion was reported in the Registration Study. During the three years covered by the study, rates of induced abortion increased by 54 percent, reflecting a trend in the incidence or in the reporting of events or in both. We concluded that, in any case, the data for the final year of the study, 1968, were more complete than for the earlier two years. 2. Age-specific rates of induced abortion for 1968 displayed a strong urban-rural gradient, being much higher in the city areas than in the rural areas. Within each urban--rural stratum, the rates increases monotonically with age and reached maximum values in the age group 40 and older (553, 436, and 374 per 1,000 pregnancies for city, urban, and rural areas, respectively). 3. Estimates of the demographic effect indicated that, in the absence of induced abortion, the TFR for all Taiwan would have been 12 percent higher in 1968. Under the same assumption, it was estimated that the TFR would have been higher by 16 percent in city areas, 11 percent in urban areas, and 9 percent in rural areas. This urbanization gradient implies that induced abortion contributed to urban-rural fertility differentials. We estimated that about one-third of those differentials were due to induced abortion. 4. Estimates of the demographic effect were also made after adjusting the rates of induced abortion for an assumed level of underreporting of 50 percent. The adjusted estimate of the demographic effect for all Taiwan in 1968 was 19 percent.

Abortion, Induced↗
PubMed1975

The diagnosis of pheochromocytoma. Overnight excretion of catecholamine metabolites.

The diurnal variation of urinary vanillylmandelic acid (VMA) and metanephrine-normetanephrine levels was studied in six patients with phechromocytoma and 32 patients with essential hypertension. Despite variable degrees of day-night differences, urinary excretion of VMA and metanephrines, per unit of time or per gram of urinary creatinine, was invariably higher in patients with pheochromocytoma than in controls whether the collection was 7 AM through 7 PM or 7 PM through 7 AM. Thus, shorter study periods are sufficient to exclude the presence of a chromaffinoma in most patients with hypertension.

Adrenal Gland Neoplasms↗
PubMed1975

Alterations in norepinephrine pattern in the damaged myocardium in the rat.

In the albino rat, the evolvement of myocardial necrosis induced by a single injection of ISO was accompanied by a fall in total NE. Pretreatment with propranolol and pargyline protected against ISO-induced necrosis and myocardial hypertrophy, but did not influence the ISO-induced depletion of NE stores. The depletion of NE stores is not due to impairment in synthesis or increased intraneuronal metabolism of NE since, in ISO-treated rats, neither cardiac tyrosine hydroxylase activity nor MAO activity was altered. The decrease in endogenous NE is not due to a defect in the storage of NE. The ability of myocardium to take up and store NE returned to normal within 48 hours, whereas endogenous levels returned to normal within 5 days, even in the presence of demonstrable necrosis. Thus, there is lack of correlation between chemical and morphological changes, since catecholamine depletion occurred in the absence of morphologically demonstrable tissue injury, and the function of the adrenergic neuron returns to normal in the presence of demonstrable necrosis.

Animals↗