Showing papers by "Drexel University published in 1971"

Ventricular fibrillation. A possible mechanism of sudden death in patients and Wolff-Parkinson-White syndrome.

Abstract: A case of Wolff-Parkinson-White syndrome associated with ventricular fibrillation is presented. The control of recurrent ventricular fibrillation with large doses of digitalis and other antiarrhythmic drugs, including propranolol, lidocaine, procainamide, and quinidine, is discussed. As far as we can determine, this is the first human case in which the precise onset of ventricular fibrillation was documented. Possible mechanisms are presented that may produce ventricular fibrillation in patients with Wolff-Parkinson-White syndrome associated with atrial flutter or fibrillation.

Hemodynamics of Uremic Anemia

Abstract: This study was undertaken to assess the importance of an elevated cardiac output in the generation of the hypertension associated with chronic renal failure. Forty stable uremic patients on a program of maintenance hemodialysis underwent hemodynamic studies. Cardiac index measured by dye dilution was found to be significantly elevated. Calculated peripheral vascular resistance was normal despite elevated blood pressure. Six patients underwent serial hemodynamic studies over a period of 6 to 12 weeks while being transfused with packed red blood cells to a normal hematocrit. Blood volume and body weight were constant during the study period. Cardiac index decreased during transfusion, reaching a normal level at a hematocrit of 30%. Diastolic blood pressure progressively rose, averaging an increase of 20 mm Hg at a hematocrit of 40%. Peripheral vascular resistance increased by 80% at a hematocrit of 40%. We concluded that the elevation of cardiac index in uremic patients is secondary to anemia and is reversi...

Antihypertensive Effect of Clonidine

Abstract: Clonidine hydrochloride is a sympathetic inhibitor with central site of action. The antihypertensive effect in man in the supine position is associated with a decrease in cardiac output and no cons...

Scleroderma and the Subcutaneous Tissue

Abstract: Our study revealed that as observed with both light and electron microscopy the most specific abnormality in sclerodermna skin is the replacement of the subcutaneous tissue by markedly abnormal connective tissue.

Material handling system

Abstract: A fork lift truck, in preferred form, has a base frame, a rack frame, a mast, and an operator''s platform. There is no center section at the bottom of the vehicle. The assembly is held together at the top with an arch formed by the mast and the truck rack frame. Two tie bars, one on each side on the vehicle, tie the frame together near the bottom. The tie bars are adjustable for height. A rigid mast supports an assembly which includes a carriage having a pivot-and-slide mechanism and a reach mechanism on which the fork is mounted. The pivot-and-slide mechanism permits the reach mechanism and its fork to be rotated and to be slidingly moved transversely from one side to the other. Thus, the mechanism permits the forks to deposit or to withdraw a load in both forward and side positions. An operator''s platform is mounted on the truck forward of the mast.

Clonidine: a new antihypertensive agent.

Abstract: Intravenous administration of clonidine in hypertensive patients resulted in a short, hypertensive response followed by a prolonged reduction of both systolic and diastolic pressure. The antihypertensive response was associated with a decrease of total forearm blood flow, while the muscle blood flow of the calf was unchanged or moderately increased. Skin blood flow showed a sharp reduction initially, followed by a slow return to control levels. In patients with essential hypertension the reduction in blood pressure after acute oral administration of clonidine was associated with a decrease in cardiac output in the supine position. In contrast, in the upright position, a reduction in both cardiac output and total peripheral resistance were observed. During the antihypertensive response, renal blood flow and glomerular filtration rate were maintained, both acutely and chronically. Intravenous or intramuscular administration of clonidine proved to be very effective in hypertensive emergencies. In 174 hospitalized patients, prolonged oral administration resulted in significant improvement of the blood pressure in 61 percent of the cases. In 115 ambulatory patients, significant improvement occurred in 64 percent. Clonidine was added to the therapeutic regimen of 20 ambulatory patients who had remained hypertensive during diuretic therapy alone, and 16 (80 percent) of the 20 showed a significant antihypertensive response in both the supine and upright positions. The most common side effects were drowsiness and dryness of the mouth. Because of its marked efficacy and the beneficial cardiovascular and renal effects, clonidine represents a most useful addition to our antihypertensive armamentarium.

Utilization of glucose by Clostridium thermocellum: presence of glucokinase and other glycolytic enzymes in cell extracts.

Abstract: Clostridium thermocellum was shown to ferment glucose in a medium containing salts and 0.5% yeast extract. An active glucokinase was obtained with improved conditions for growth, assay, and preparation of cell extracts. Cell extracts appear to contain a glucokinase inhibitor that interferes with the assays at high protein concentrations. Glucokinase activity is stimulated about 60% by pretreatment with dithiothreitol. Little or no fructokinase or mannokinase activity was detected in cell extracts. The absence of glucokinase in mannitol-grown cells, the increase in glucokinase activity upon incubation of cell suspensions with glucose, and the lack of increase in activity when chloramphenical is added are evidence that glucokinase is an inducible enzyme. The following enzymes were detected in cell extracts (the enzyme activities are shown in parentheses are micromoles per minute per milligram or protein at 27 C): glucokinase (0.48), phosphoglucose isomerase (0.73), fructose 6-phosphate kinase (0.24), fructose diphosphate aldolase (0.59), glyceraldehyde 3-phosphate dehydrogenase (0.53), triose phosphate isomerase (0.13), phosphoglycerate kinase (0.20), phosphoglycerate mutase (0.20), enolase (0.28), pyruvic kinase (0.13), and lactic dehydrogenase (0.13). Glucose 6-phosphate dehydrogenase activity was absent or very low (0.0002) and 6-phosphogluconate dehydrogenase activity also was relatively low (0.015). From these data, it is proposed that carbohydrate metabolism in C. thermocellum proceeds by the Embden-Meyerhof pathway.

Further study of composite laminates under cylindrical bending.

Abstract: In a series of three papers [1,2,3], the range of applicability of classical laminated plate theory (CPT) in describing the response of composite laminates under static bending has been examined. Briefly, exact solutions within the framework of linear elasticity theory were developed and compared to the respective solutions governed by CPT [4,5,6]. Numerical data calculated based on simple harmonic load distributions have indicated rather wide discrepancy between the two solutions for laminates having low span-to-depth ratios. At high aspect ratios however, the CPT solution is in good agreement with the elasticity solution.

Ethacrynic acid and furosemide. Diuretic and hemodynamic effects and clinical uses.

Abstract: Ethacrynic acid and furosemide are the most potent diuretic agents currently available. Although the evidence for a proximal tubular site of action is conflicting, the main action of both agents is inhibition of sodium reabsorption along the ascending loop of Henle. Acute administration of ethacrynic acid and furosemide may produce a transient slight increase in both glomerular filtration rate and renal plasma flow, which is followed by a decrease in glomerular filtration rate and renal plasma flow with diuresis and dehydration. In patients who do not have congestive heart failure, acute administration of either drug results in a decrease in plasma volume, central venous pressure and cardiac index, and an increase in arteriovenous oxygen differences. In patients with severe congestive heart failure, plasma volume and central venous pressure fall, but cardiac index increases and arteriovenous oxygen difference narrows. Both drugs have rapid and short duration of diuretic action and wide and steep dose-response curves. Therefore, both drugs can be used in patients with mild to severe congestive heart failure or fluid retention. Both drugs are also effective despite the presence of hypoalbuminemia, acid-base and electrolyte imbalance and a low glomerular filtration rate. Therefore, refractoriness to either agent is unusual in the absence of severe renal failure. Neither drug has been widely used for antihypertensive therapy. No marked difference in antihypertensive potency from that of standard thiazide drugs has been noted. Both drugs are especially useful in those patients with severe hypertension who have concomitant renal failure or congestive heart failure. In this group of patients they help to maintain adequate urinary output and potentiate other antihypertensive drugs. Despite the potent diuretic action of both drugs, side effects are relatively infrequent. However, close monitoring of diuretic response, and acid-base and electrolyte status is recommended.

Catabolism of Fructose and Mannitol in Clostridium thermocellum: Presence of Phosphoenolpyruvate: Fructose Phosphotransferase, Fructose l-Phosphate Kinase, Phosphoenolpyruvate: Mannitol Phosphotransferase, and Mannitol l-Phosphate Dehydrogenase in Cell Extracts

Abstract: Fructose and mannitol are fermented by Clostridium thermocellum in a medium containing salts and 0.5% yeast extract. The initial reaction in the catabolism of fructose was found to be the formation of fructose l-phosphate by phosphoenolpyruvate (PEP):fructose phosphotransferase which resembles the Kundig-Roseman phosphotransferase system. The phosphorylation of fructose l-phosphate to form fructose-1, 6-diphosphate is catalyzed by fructose l-phosphate kinase. Fructose-1, 6-diphosphate can be further metabolized by the Embden-Meyerhof pathway. The formation of both PEP:fructose phosphotransferase and fructose l-phosphate kinase is induced by growth in fructose medium. Mannitol catabolism was found to proceed by the phosphorylation of mannitol by PEP:mannitol phosphotransferase to form mannitol l-phosphate. Mannitol l-phosphate is converted to fructose 6-phosphate by a nicotinamide adenine dinucleotide-specific mannitol l-phosphate dehydrogenase. The fructose 6-phosphate formed in the reaction can enter the glycolytic scheme. The formation of both PEP:mannitol phosphotransferase and mannitol l-phosphate dehydrogenase is induced by growth in mannitol medium. Evidence is presented for the induction by mannitol of PEP:mannitol phosphotransferase and mannitol l-phosphate dehydrogenase in suspensions of fructose-grown cells.

Traumatic aneurysm of the left coronary artery

Abstract: To our knowledge, this is the first reported case of the development of an aneurysm of a major coronary artery secondary to a traumatic wound to the heart. The patient sustained a single shotgun pellet wound to the heart, the pellet hitting the left anterior descending coronary artery and lodging in the wall of the left atrium. The patient incurred an anteroseptal wall infarction and had an uneventful recovery. Selective coronary artery visualization performed 4 weeks and 6 months after the injury occurred revealed a localized aneurysm of the anterior descending artery. The problems presented by this lesion are discussed.

Syndromes of Disturbed Classroom Behavior: A Behavioral Diagnostic System for Elementary Schools

Abstract: I The authors express appreciation to Dr. Perry Scheinok and his staff at the Computer Center of Hahnemann Medical College and Hospital for their assistance. The contribution of the third author was supported by USPHS grants 5-RO1-GM-16193 and USPHS PR-15. 2 Now at the Division of Computer Research and Technology, National Institutes of Health, Bethesda, Md. In the inaugural issue of this journal, the investigators presented the results of a factor analytic study of the classroom behavior of normal and abnormal (special education) elementary school children (Spivack & Swift, 1966). This was the first of a series of studies, the primary aims of which were to better understand the nature

Electrical Resistivity of a Polymeric Insulator containing Segregated Metallic Particles

Abstract: GURLAND1 has studied the decrease in electrical resistivity of an insulating polymeric material caused by inclusion of randomly distributed spherical particles of metal. It was shown that the resistivity of a phenolic polymer (“bakelite”) was little affected by inclusion of silver particles below a volume percentage of 35–37, but that beyond this level the resistivity decreased markedly. Evidence that the spherical particles of silver were randomly distributed was obtained by microscopic examination of polished sections of compacts. Comparison of the frequency of particle to particle contacts with probability theory and subsequently with percolation models2, suggested that the abrupt decrease in resistivity at 35–37% corresponded to the onset of the formation of infinitely long chains of connected metallic particles.

Electron microscope radioautographic identification of serotonin-synthesizing cells in the mouse gastric mucosa

Abstract: This study correlates the fine structure of mouse gastric endocrine cells with their ability to synthesize serotonin (5-HT) from 5-hydroxytryptophan (5-HTP). Mice were sacrificed 2 hr after the intravenous injection of 5-HTP-3H or 5-HT-3H. Their stomachs were processed for light- and electron microscope radioautography in a manner which retained labeled 5-HT while washing out other labeled substances. Stomachs from additional mice were incubated in vitro with 5-HT-3H and processed similarly. All morphologic types of mouse gastric endocrine cells exhibited a similar facility to incorporate exogenous 5-HTP and to convert it to 5-HT which was bound intracellularly. Differences in densities of silver grains observed over endocrine cells suggested that individual endocrine cells indeed varied in their ability to synthesize and/or to bind 5-HT; such variations, however, were not reflected by differences in fine structure, with the exception that endocrine cells with few granules always contained little newly synthesized 5-HT. The newly synthesized 5-HT was associated with the intracellular granules. The gastric endocrine cells were not labeled by exogenous 5-HT-3H, whereas mast cells were labeled by either 5-HT-3H or 5-HTP-3H administration. The findings of the present study support the position that the gastric endocrine cells represent a single cell type, at least in respect to serotonin metabolism—that the argyrophil or argentaffin reactivity of these cells merely reflects their amine content at a given time.

Strain instability and fracture at the surface of upset cylinders

Abstract: A refined method has been developed for measurement of the localized surface strains during axial compression of cylinders. The method has been applied to 1045 steel cylinders in various conditions to study fracture under combined stress states. Because the refined measurement method is used, perturbations are observed in the strain path which would otherwise not be apparent. These perturbations precede surface fracture in every case. It is shown that geometric similarities exist between the strain perturbations in upsetting and those in trough formation preceding fracture in stretch forming of sheet material. In addition, metallographic examination of transverse sections of the upset cylinders reveals the presence of subsurface void formations prior to fracture. It is concluded that the surface fractures in upset cylinders involve localized necking of material between inhomogeneities, and it is suggested that an accurate model of this behavior may give some understanding of the influence of material parameters on fracture.

Myocardial infarction and oral contraceptive agents

Abstract: Three young premenopausal women, aged 27, 29 and 35 years, with acute myocardial infarction in the absence of significant predisposing causes are presented. All 3 patients were taking oral contraceptive agents at the time of infarction. Selective coronary arteriograms showed an isolated segmental occlusion in all cases with no other arterial disease. Although these events must be considered rare, oral contraceptive agents may be a possible contributing factor in myocardial infarction by a mechanism of thrombosis. The role of estrogens in myocardial infarction and atherosclerosis is reviewed. The implication of these cases for increased incidence of thromboembolic disorders in clinical trials of estrogen in atherosclerotic disease is discussed.

Product type quadrature formulas

Abstract: This paper is concerned with the numerical approximation of integrals of the forme f(x)g(x)dx by means of a product type quadrature formula. In such a formula the functionf (x) is sampled at a set ofn+1 distinct points and the functiong(x) at a (possibly different) set ofm+1 distinct points. These formulas are a generalization of the classical (regular) numerical integration rules. A number of basic results for such formulas are stated and proved. The concept of a symmetric quadrature formula is defined and the connection between such rules and regular quadrature formulas is discussed. Expressions for the error term are developed. These are applied to a specific example.

Development and chromosomal constitution of nuclear-transplants derived from male germ cells.

Abstract: Nuclei of spermatogonial cells derived from juvenile and adult (Rana pipiens) were transplanted singly into enucleated eggs to determine whether germ cell nuclei are developmentally totipotent. Control nuclear transfers from undetermined somatic cells promoted genuine cleavage in 77% of the injected eggs and 54% of the complete blastulae derived from this series developed into normal larvae. In contrast to the control study, eggs transplanted with germ cell nuclei formed genuine blastulae in 13% of the cases, and most of the complete blastulae arrested before completing gastrulation. However, three embryos derived from adult germ cell nuclei did attain advanced stages of organogenesis and one of these developed into an abnormal feeding larva. These individuals are the most advanced nuclear-transplants obtained so far from nuclei of normal adult cells in vivo. Chromosome analyses performed on a sample of nuclear-transplants derived from germ cells revealed gross chromosomal abnormalities in all individuals except the larva. It is concluded, that even though germ cell nuclei are genetically totipotent, they, like somatic nuclei, undergo developmental restrictions during their process of cell differentiation, and after transplantation to host eggs, give rise to abnormal nuclear-transplants accompanied in most cases by karyotypic alterations. The significance of the developmental restrictions observed in germ cell nuclei is interpreted as an expression of chromosomal differentiation.

Recurrent Wolff-Parkinson-White tachycardia in an infant: Successful treatment by a radio-frequency pacemaker

Abstract: A 5 week old infant was successfully treated with use of a radio-frequency pacemaker to terminate recurrent Wolff-Parkinson-White tachycardia. In this instance temporary electronic pacing and later implantation of a permanent pacemaker was lifesaving. The mechanism for termination of Wolff-Parkinson-White tachycardia by pacemaker stimulation is reviewed. This method may have application in any type of recurrent tachycardia in infants as well as adults.

A study of the effect of an intermediate phase on the dissolution and homogenization characteristics of binary alloys

Abstract: The effect of an intermediate phase on the dissolution and homogenization characteristics of binary alloys was studied by mathematically modeling finite, three-phase, diffusion-controlled, binary systems for planar, cylindrical, and spherical interfaces with the mean composition in a terminal solid solution (α). Calculations were carried out using numerical methods and computer techniques. The major variables affecting the dissolution of the unstable terminal solid solution (γ) and the intermediate phase (β) were found as well as the variables affecting the homogenization process. Comparison of the results to existing solutions for one-phase (Heckel18) and two-phase (Tanzilli and Heckel16) binary systems led to predictions for the behavior ofn-phase binary systems. Calculations based on the spherical model were successfully compared to existing literature data for dissolution in a compacted blend of W−Re powders and for the formation of austenite from ferrite and cementite.