Biomedical subjects
Publications and source records attributed to R Ringel.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
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Examination of gastrin-immunoreactive G-cells, somatostatin-immunoreactive D-cells, enterochromaffin cells and 5-hydroxytryptamine-immunoreactive (5-HT-immunoreactive) cells of the completely mapped histologic antrum (70 to 100 tissue blocks) was done in 20 normal stomachs of persons between 17 and 94 years of age (from forensic autopsy). Results were compared with those of nine patients between 48 and 76 years of age with total gastrectomy for carcinoma of the proximal part of the stomach. Cell counts and morphometric examinations were performed. Results were summarized for the proximal (I), middle (II) and distal (III) one-third of the antrum and for the major (A) and minor (B) curvature side. In normal stomachs, the G-cell count was 2.52 percent of the total gland cell count in AI; 4.25 percent in AII and 4.77 percent in AIII. In BI, the numbers were 2.5 percent, in BII, 3.73 percent and 4.06 percent in BIII. The D-cell count was 0.47 percent in AI, 0.62 percent in AII and 0.58 percent in AIII. The numbers were 0.44 percent in BI, 0.51 percent in BII and 0.51 percent in BIII. In the antrum of the stomach with carcinoma, the G-cells revealed a non-significant 20 to 70 percent lower cell count, while the D-cell count was reduced insignificantly by as much as 35 percent in all areas. The 5-HT-immunoreactive cell count in normal stomachs is 0.25 percent in AI of the total gland cells, 0.32 percent in AII and 0.39 percent in AIII. In B, it shows numerically no difference to that of A. Contrary to the cell count in normal stomachs, the carcinoma antrum revealed a 200 to 400 percent increase in 5-HT-immunoreactive cell count, highly significant in every area of the antrum. Because 5-HT is known as a growth stimulant, especially for tumors, an increase in 5-HT-immunoreactive cells may be a factor that contributes to the initial histologic changes observed during the early phase of gastric tumor.
Digoxin-like inhibitors of Na,K-ATPase have been implicated in the pathophysiology of essential (EH) and pregnancy-induced hypertension (PIH). A technique that enhances dissociation of digoxin from red blood cells (RBC) was used to displace endogenous digoxin-like substances from RBCs. RBC membranes were preincubated in Na and ATP (Release) or Na,K,Mg and ATP (Retention) prior to measuring ATPase activity. Groups studied were: 39 men with EH and 34 controls plus 10 women with PIH and 17 normotensive controls. All displayed similar increases in Na,K-ATPase activity (24.0 +/- 7.9%) following Release. Plasma digoxin immunoreactivity (DI) was measured in pregnant women, m = 0.25 +/- 0.07 ng/ml. No DI was detected in nonpregnant women, but RBCs from these women demonstrated the same increase in Na,K-ATPase activity after Release. The 24% increase in activity achieved by Na and ATP preincubation can be reversed by adding K and Mg to the Release suspension. However, after RBC-bound digoxin is displaced by Release preincubation, addition of K and Mg cannot promote renewed binding and pump inhibition. Thus, the observed endogenous inhibition is not due to displacement of a digoxin-like substance but probably is related to alteration of the enzyme-membrane interaction. Furthermore, even though pregnant women demonstrate DI, an inhibitory substance with digoxin-like binding could not be recognized using this technique.
Five nonsingers and five singers vocally matched the pitches of frequency modulated tones. Subject responses to the shadowing task were analyzed in terms of accuracy, and in terms of duration and speed characteristics of pitch changes. In addition, each frequency change was categorized according to hit, overshoot, undershoot, or oscillate patterns. Singers were found to effect pitch changes in significantly less time than the nonsingers. This finding was attributed to more direct patterns (hits) and faster maximum speeds obtained by the singers. Both groups demonstrated a direct relationship between the size of the pitch change and each of the duration and speed parameters examined. Similarly, for both groups, pitch lowering was faster than pitch raising. Faster speeds and more direct paths in effecting pitch changes were viewed as evidence of greater vocal proficiency in singers as compared to nonsingers. Implications of the data for mechanical and physiological aspects of voice frequency control are discussed.
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Elements of a hypothesis that relate endogenous digitalis-like factors to both natriuretic hormone and hypertension are briefly reviewed. The stimulus for secretion of these factors appears to involve a tendency toward a state of extracellular fluid volume expansion as a consequence of an inherited or an acquired defect in renal function. Several studies implicate the brain and, in particular, the hypothalamus in the control of the secretion. The digitalis-like factors are thought to act by partial inhibition of active sodium transport, thereby promoting increased intracellular levels of Na+ and Ca2+ in a variety of cell types. In the kidney, inhibition of sodium transport leads to a compensatory natriuresis to correct the tendency for volume overload. In smooth muscle, the inhibition of sodium transport will indirectly increase intracellular calcium levels. The increased availability of Ca2+ will elevate muscle tone and increase peripheral vascular resistance. Also presented are criteria that may be used to characterize digitalis-like activity in samples and extracts obtained from purification procedures. Finally, we review our measurements of the 6-h integrated plasma levels of digitalis-like factors and other hormones for normotensive subjects and patients with essential hypertension. The data indicate the presence of two classes of digitalis-like factors with potentially different roles in electrolyte metabolism and hypertension.
Between July 1979 and October 1984, 61 systemic-pulmonary arterial shunts were created in 45 patients. Clinical and angiographic results with 23 classic Blalock-Taussig shunts (BTSs) and 35 modified Blalock-Taussig shunts (MBTSs) with polytetrafluoroethylene grafts between the subclavian and pulmonary arteries were compared. Forty-three of the patients studied were infants: 28 were less than 1 month old, and 19 were less than 1 week old. Weights were 1.1 to 19 kg (mean 2.9 kg). Diagnoses were complex tetralogy of Fallot (18 patients), transposition of the great arteries with small left ventricle or left ventricular outflow tract obstruction (six patients) pulmonary atresia (seven patients) with intact ventricular septum (three) and ventricular septal defect (four), tricuspid atresia (four patients), univentricular heart (six patients), atrioventricular septal defect (canal) with pulmonary stenosis (three patients), and double-outlet right ventricle (one patient). Comparison groups were concurrent and were equivalent for age, weight, and complexity of anomaly. Patients were removed from the study population at the time of subsequent open heart surgery or at death. All patients were followed for a minimum of 6 months and for up to 5 1/2 years (BTS 1 1/2 to 5 1/2 years, mean 33 months; MBTS 6 months to 3 years, mean 20 months). There were no intraoperative deaths in either group. Among the 23 BTSs, three failed at 1, 3, and 19 days, resulting in two deaths (17%). One premature infant died despite a second shunt, one died during attempted intracardiac repair at 13 days of age, and the other was well after revision of the shunt. Eight patients underwent subsequent intracardiac repair 1 to 5 years (mean 34 months) after the initial procedure. Another four patients died from complex intracardiac anomalies with patent shunts. Three patients are alive 2 to 4 years after receiving shunts and have not undergone subsequent surgery. Late postoperative angiograms demonstrate a disturbing incidence (21%) of stenosis and right pulmonary arterial deformity despite satisfactory immediate postoperative studies and good clinical function. Eight patients required a second shunt, two for anatomic discontinuity of the pulmonary arteries and six because of inadequate blood flow through the first shunt. Among the 35 patients receiving the MBTS, two required early revision (technical error and ductal tissue at the anastomosis). There were no shunt-related deaths, but three (6%) occurred within 30 days of operation from left ventricular infarct, cerebral hemorrhage, sepsis, and severe aortic stenosis with arrhythmias.(ABSTRACT TRUNCATED AT 400 WORDS)
The subclavian flap repair for coarctation of the aorta allows potential for growth by utilizing autogenous tissue. Although well documented in young children, its promise in the tiny neonate warrants further evaluation. Since August, 1979, 29 patients, including 24 infants, have undergone subclavian flap repair at the University of Maryland Hospital. Weights ranged from 1.4 to 5 kg (mean 3.2 kg). All patients less than 6 months old had associated intracardiac defects and were in severe congestive failure. Fifteen responded to preoperative prostaglandin infusions. The overall early mortality was 14%; among the neonates it was 21%; and among those operated upon within the first week of life, 33%. There was one intraoperative death among the eight patients who underwent simultaneous pulmonary artery banding. There were no deaths among patients older than 5 days at operation. Four of the five neonates who died had some variant of hypoplastic left heart syndrome, with severe stenosis or atresia of the systemic atrioventricular valve, critical aortic stenosis, or hypoplastic left ventricle. Twenty-two survivors continue to do well up to 3.7 years postoperatively (mean follow-up 26 months). At follow-up all patients are normotensive with brisk lower extremity pulses. Patients now weigh 1.3 to 6.9 (mean 2.3) times their operative weight, and only one patient has a measured arm-to-leg gradient greater than 10 mm Hg (mean gradient 3.7 mm Hg). Seven of the neonates have undergone repeat catheterization, and all had satisfactory growth of the subclavian flap segment of repair and no gradient. Two older patients (3 and 4 years old at operation) have undergone exercise testing 3.7 years after repair, with peak exercise gradients of only 7 and 15 mm Hg. We therefore continue to utilize this technique for the treatment of coarctation even in tiny neonates.
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Computed axial tomography was performed in an infant with severe respiratory distress. A right aortic arch and paratracheal density was visualized, suggesting a vascular ring. Angiography confirmed a right aortic arch, mirror-image branching, and a left patent ductus arteriosus.
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