PubMed Health⌕ Search

Biomedical subjects

S Fox

Publications and source records attributed to S Fox.

At least 127 records · Page 7Linked to original sources
PubMed1981

Pacemaker syndrome: a non-invasive means to its diagnosis and treatment.

Vertigo, lightheadedness, syncope, and hypotension occurring after implantation of a ventricular pacemaker has become known as pacemaker syndrome. In one patient with this syndrome we have demonstrated an associated decrease in the pulse amplitude of the ophthalmic arteries during ventricular pacing by utilizing ocular pneumoplethysmography (O.P.G.). This non-invasive technique was subsequently used intra-operatively to test the presence of ophthalmic artery pulse amplitude changes after implantation of the ventricular electrode. An A-V sequential pacemaker was then implanted and eliminated all symptoms of pacemaker syndrome.

Bradycardia↗
PubMed1981

Simplified technique for permanent atrioventricular pacing via a single venipuncture.

The use of physiologic pacing utilizing transvenous atrial and ventricular electrodes has recently taken on increased importance. A simple, safe, technique for electrode implantation has been used in 14 patients and enabled the implanting physicians to establish permanent atrioventricular (A-V) sequential pacing with low risk in a short span of time.

Atrioventricular Node↗
PubMed1980

Pathogenesis of paradoxical hypertension after coarctation repair.

A recent review of 25 patients who had repair of coarctation of the aorta at the Milton S. Hershey Medical Center revealed a 56% incidence of paradoxical hypertension in the immediate postoperative period. Analysis of results from recent animal experiments helped us to formulate a logical explanation of the pathogenesis of this hypertension. Stimulation of sympathetic nerve fibers located between the media and adventitia of the aortic isthmus has two effects, both of which result in hypertension. The first effect is release of norepinephrine and consequential rise in systemic blood pressure. Second, this spinal reflex directly stimulates the juxtaglomerular cells to release renin and cause additional hypertension. An additional effect of this increased renin production might be the shunting of blood from mesenteric arteries, thus causing the abdominal symptoms of so-called post-coarctectomy syndrome. The inability of some patients to adapt to this spinal reflex may be related to the age of the patient when the coarctation was repaired. This probably explains the high incidence of persistent hypertension in patients who undergo coarctation repair after adolescence.

Adolescent↗
PubMed1980

Pathogenesis of diabetic gastroparesis: a pharmacologic study.

The motor function of the antrum was studied in 7 normal subjects, 4 patients with diabetes without GI symptoms, and 7 patients with diabetic gastroparesis. Both the number of antral contractions and the cumulative antral activity (percent of time during which the antrum contracted) in patients with diabetic gastroparesis were significantly lower than in normal subjects and diabetic patients without gastroparesis (P less than 0.01). Interdigestive motor complexes were observed in all normal subjects, but they were not present in any patients with diabetic gastroparesis. Intravenous metoclopramide did not affect the rate of antral contractions (P less than 0.1), but it increased the cumulative antral activity (P less than 0.001) in normal subjects and diabetics without gastroparesis. Metoclopramide, however, did not alter the rate of antral contractions (P less than 0.09) or the total cumulative antral activity (P less than 0.09) in diabetic patients with gastroparesis. Furthermore, in normal subjects, the action of metoclopramide was blocked by atropine sulfate (P less than 0.003). Bethanechol caused a slight increase in the number of antral contractions (P less than 0.05) and cumulative antral activity (P less than 0.01) in normal subjects. This cholinergic drug caused a marked increase in the rate of antral contractions and the cumulative antral activity in diabetic patients with gastroparesis. Antral contractions and cumulative antral activity were restored by bethanechol to normal values. These findings suggest a variable degree of gastric neuropathy in individual patients with diabetic gastroparesis with functionally intact antral muscles as assessed by their pharmacologic response to cholinergic stimulation.

Adult↗
PubMed1979

Acute hypertension: its significance in traumatic aortic rupture.

Traumatic aortic rupture is a common occurrence associated with 16 percent of deaths from automobile accidents. Through a review of current literature and two recent cases from The Milton S. Hershey Medical Center, we have attempted to elucidate a common physical finding, acute hypertension associated with blunt chest trauma, and prove its significance as a diagnostic clue to traumatic rupture of the aorta. New laboratory findings of an aortic sympathetic reflex stimulated by stretching the aortic wall in the area of the isthmus provides a physiological explanation for the cause of hypertension after aortic trauma.

Accidents, Traffic↗
PubMed1977

Echocardiographic diagnosis of acute aortic valve endocarditis and its complications.

Staphylococcus aureus aortic valve endocarditis and its complications in a patient were readily recognized by echocardiography. "Shaggy" echoes recorded from the aortic leaflets in diastole as well as irregular diastolic densities in the left ventricular outflow tract suggested flail aortic leaflets secondary to bacterial endocarditis. The presence of a double echo of the anterior aortic wall was an unusual finding. Initially thought to represent a localized dissection, abscess formation and pocket of edematous fluid accumulation was found between the anterior aortic wall and pulmonary artery. Premature closure of the mitral valve was evident shortly before the patient died. The specific echocardiographic features of flail aortic leaflets and premature mitral valve closure should alert the physician to consider immediate aortic valve replacement.

Adult↗
PubMed1975

Role of neonatal androgen in the development of hepatic microsomal drug-metabolizing enzymes.

The development of several hepatic microsomal drug-metabolizing enzyme activities in rats was studied in relation to its androgen dependence during the neonatal period. Rats with their androgen deprived during the neonatal period (female rats and male rats castrated at birth) respond less to androgen treatment at adulthood for the metabolism of aminopyrine, ethylmorphine and hexobarbital as compared to rats exposed to neonatal androgen (male rats, male rats castrated at birth but neonatally treated with androgen and male rats castrated at the age of 20 days). This difference in the degree of hepatic responsiveness, however, varied with the substrates: ethylmorphine N-demethylase activity was affected the most whereas aminopyrine N-demethylase and hexobarbital oxidase activities were only marginally affected. Furthermore, these differences in responsiveness seem to be a delayed event, since hepatic aminopyrine N-demethylase activity in rats castrated at birth did respond to androgen stimulation during the prepubertal period and became insensitive to this same androgen stimulation at adulthood. The effect of neonatal androgen on the apparent Michaelis constant (Km) of ethylmorphine N-demethylase was also studied in the adult rat. Rats castrated at birth had a Km value (0.75 plus or minus 0.15 mM) similar to that of the females (0.95 plus or minus 0.13 mM). However, rats castrated at birth but neonatally treated with androgen and rats castrated at the age of 20 days exhibited Km values (0.29 plus or minus 0.06 and 0.25 plus or minus 0.06 mM, respectively) similar to that of the males (0.35 plus or minus 0.15 mM). The significance of neonatal androgen in the development of hepatic microsomal drug metabolizing enzyme system is discussed.

Aminopyrine N-Demethylase↗