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Articles 331 - 360 of 417

Full-Text Articles in Biomedical Engineering and Bioengineering

Interposed Abdominal Compression As An Adjunct To Cardiopulmonary Resuscitation, Charles F. Babbs, Jeffrey B. Sack, Karl B. Kern Jan 1994

Interposed Abdominal Compression As An Adjunct To Cardiopulmonary Resuscitation, Charles F. Babbs, Jeffrey B. Sack, Karl B. Kern

Weldon School of Biomedical Engineering Faculty Publications

The addition of interposed abdominal compression (IAC) to otherwise standard CPR provides external pressure over the abdomen in counterpoint to the rhythm of chest compression. Interposed abdominal compression is a simple manual technique that can supplement the use of adrenergic drugs to increase both coronary perfusion pressure and total blood flow during CPR. Mechanistically, manual abdominal compressions induce both central aortic and central venous pressure pulses. However, owing to differences in venous versus arterial capacitance, the former are usually greater than the latter, so that systemic perfusion pressure is enhanced. Moreover, practical experience and theoretical analysis have suggested subtle refinements …

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Toward Virtual Digital Mammograms For Research And Training In Tumor Detection, Charles F. Babbs, Leslie A. Geddes Dec 1993

Toward Virtual Digital Mammograms For Research And Training In Tumor Detection, Charles F. Babbs, Leslie A. Geddes

Weldon School of Biomedical Engineering Faculty Working Papers

Research in the processing, compression, transmission, and interpretation of digital radiographic images requires evaluation of a wide variety of test images, varying in format, in spatial resolution, and in anatomic content. To evaluate the diagnostic performance of observers using novel versus conventional image formats, large numbers of test images containing known abnormalities are required. This report describes a method for creating high resolution, virtual digital mammograms from computational models of the human breast that include branched lobulated ducts and suspensory ligaments embedded in fatty subcutaneous tissue. Breast phantoms may include any of three types of simulated tumors (fibroadenomas, invasive ductal …

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Interposed Abdominal Compression Cardiopulmonary Resuscitation: Are We Missing The Mark In Clinical Trials?, Charles F. Babbs Jan 1993

Interposed Abdominal Compression Cardiopulmonary Resuscitation: Are We Missing The Mark In Clinical Trials?, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

Straightforward considerations of abdominal anatomy in human beings set tight constraints on the theoretically optimal technique for abdominal compressions during interposed abdominal compression (IAC)-CPR. The location and extent of the abdominal aorta lead naturally to the recommendation that IAC be applied at a level corresponding to the lower two thirds of the sterno-umbilical line. The force vector required to achieve contact compression of the abdominal aorta is inclined in the transverse plane at an angle of 11 degrees from the vertical toward the left. Such slightly angled compression subjects the abdominal aorta to maximally flattening; while the inferior vena cava …

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Interposed Abdominal Compression-Cpr: A Case Study In Cardiac Arrest Research, Charles F. Babbs Jan 1993

Interposed Abdominal Compression-Cpr: A Case Study In Cardiac Arrest Research, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

When the abdomen is compressed manually in counterpoint to the rhythm of chest compression, in the performance of interposed abdominal compression-CPR, artificial circulation is approximately doubled in animal experiments and in electronic models of the circulatory system. These studies suggest that external manual compression of the abdominal aorta acts like an intra-aortic balloon pump to increase aortic pressure, whereas external manual compression of the abdominal veins acts to prime the right heart and pulmonary vessels before the next chest compression. As a result, perfusion pressures and flows are increased. Several clinical studies of this technique have shown promising results, including …

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Development Of A Rapidly Computable Descriptor Of Prostate Tissue Temperature During Transurethral Conductive Heat Therapy For Benign Prostate Hyperplasia, U H. Patel, Charles F. Babbs Jan 1993

Development Of A Rapidly Computable Descriptor Of Prostate Tissue Temperature During Transurethral Conductive Heat Therapy For Benign Prostate Hyperplasia, U H. Patel, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

Benign prostate hyperplasia (BPH) is a condition in older men in which the mass of tissue in the prostate gland gradually increases over the course of many years, ultimately leading to urinary outflow obstruction. Current treatment of this condition is to surgically remove the obstructing tissue. One novel alternative therapy being studied is transurethral thermocoagulation of excessive prostatic mass. In this approach, a heat emitting catheter is placed in the prostatic urethra, and the intraprostatic segment of the catheter is heated to temperatures above 60 oC for one hour. Two dimensional cylindrical coordinate computer simulations of this treatment modality were …

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Oxidative Mechanisms In Arterial Distension Injury: Observations Relevant To Restenosis After Angioplasty, Charles F. Babbs, Yuan Zhong Nov 1992

Oxidative Mechanisms In Arterial Distension Injury: Observations Relevant To Restenosis After Angioplasty, Charles F. Babbs, Yuan Zhong

Weldon School of Biomedical Engineering Faculty Working Papers

Background: To explore the hypothesis that tissue iron and reactive oxygen species, including superoxide (O2), mediate acute inflammatory and late hyperplastic responses to vascular injury, we studied experimental overdistension of normal carotid and femoral arteries in dogs. Experimental design: Arterial segments isolated in situ were distended with Ringer solution at 2 atmospheres pressure. In initial experiments the arteries were excised immediately after distension and immersed in diaminobenzidine solutions containing Mn++ ions to initiate histochemical reactions for O2. In other experiments distended arterial segments were reperfused with arterial blood in the presence or absence of the iron chelator, deferoxamine, or the …

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Evidence That Free Fatty Acid-Iron Complexes Directly Initiate Lipid Peroxidation In Vitro And In Vivo: A New Mechanism Of Oxidative Stress, Steven C. Salaris, Charles F. Babbs, Joann Pham, John J. Turek Jun 1992

Evidence That Free Fatty Acid-Iron Complexes Directly Initiate Lipid Peroxidation In Vitro And In Vivo: A New Mechanism Of Oxidative Stress, Steven C. Salaris, Charles F. Babbs, Joann Pham, John J. Turek

Weldon School of Biomedical Engineering Faculty Working Papers

Through a series of biochemical and histochemical experiments we explored the novel hypothesis that iron and free fatty acids, liberated after tissue injury, combine to form liposoluble complexes that directly initiate lipid peroxidation. The addition of 100 M ferric iron to 30 mM linoleate suspensions at pH 7.4 produced time dependent lipid peroxidation, measured as conjugated diene formation. Complexes of 100 M ferric iron and 600 M pentanoate also initiated formation of conjugated dienes in linoleate suspensions and formation of malondialdehyde-like materials in rat liver slices. A histochemical stain for free fatty acids revealed positive reactions within cell membranes in …

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Oxygen Radicals In Ulcerative Colitis, Charles F. Babbs Jan 1992

Oxygen Radicals In Ulcerative Colitis, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

This article reviews the pathophysiologic concept that superoxide and hydrogen peroxide, generated by activated leukocytes, together with low-molecular-weight chelate iron derived from fecal sources and from denatured hemoglobin, amplify the inflammatory response and subsequent mucosal damage in patients with active episodes of ulcerative colitis. The putative pathogenic mechanisms reviewed are as follows: ( l ) Dietary iron is concentrated in fecal material owing to normally limited iron absorption. (2) Mucosal bleeding, characteristic of ulcerative colitis, as well as supplemental oral iron therapy for chronic anemia, further conspire to maintain or elevate mucosal iron concentration in colitis. (3) Fenton chemistry, driven …

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Histochemical Demonstration Of Endothelial Superoxide And Hydrogen Peroxide Generation In Ischemic And Reoxygenated Rat Tissues, Charles F. Babbs, Meloney D. Cregor, Stephen F. Badylak Jan 1992

Histochemical Demonstration Of Endothelial Superoxide And Hydrogen Peroxide Generation In Ischemic And Reoxygenated Rat Tissues, Charles F. Babbs, Meloney D. Cregor, Stephen F. Badylak

Weldon School of Biomedical Engineering Faculty Publications

Objective: The aims were to test and evaluate two novel and independent histochemical methods for detecting the initial postischemic burst of superoxide and hydrogen peroxide in buffer perfused rat tissues during reflow after 60 min warm ischemia. Methods: The first is a high manganese/diaminobenzidine technique, in which superoxide oxidises Mn2+ to Mn3+, which in turn oxidizes diaminobenzidine to form amber colored polymers, observable by light microscopy. The second is a high iron/diaminobenzidine technique, in which hydrogen peroxide oxidizes diethylenetriaminepenta-acetate chelated Fe2+ to form intermediate species, which in turn oxidize diaminobenzidine similarly to Mn3+. Various isolated organs of the rat were …

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A Computer-Based, Automated, Telephonic System To Monitor Patient Progress In The Home Setting, Umesh H. Patel, Charles F. Babbs Jan 1992

A Computer-Based, Automated, Telephonic System To Monitor Patient Progress In The Home Setting, Umesh H. Patel, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

In this report we describe an automated, telephonic system to monitor the progress of patients convalescing at home. The system includes a computerized central station that is capable of automated voice communication over the telephone, using voice reproduction, and touch-tone recognition. Peripheral hardware in multiple monitored homes need include only a touch-tone telephone, but may also be augmented by inexpensive, rudimentary diagnostic aids, such as a scale for body weight, a thermometer, or a blood pressure cuff and manometer. Current central hardware includes a NeXT computer, a fax modem, and a specialized telecommunications modem developed specifically for voice telecommunication using …

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Evidence Of Changes In Regional Blood Perfusion In Human Intracranial Tumours During Conductive Interstitial Hyperthermia, U H. Patel, Charles F. Babbs, J A. Deford, W M. Bleyer, J A. Marchosky, C J. Moran Jan 1992

Evidence Of Changes In Regional Blood Perfusion In Human Intracranial Tumours During Conductive Interstitial Hyperthermia, U H. Patel, Charles F. Babbs, J A. Deford, W M. Bleyer, J A. Marchosky, C J. Moran

Weldon School of Biomedical Engineering Faculty Publications

Human intracranial tumours were treated using local heat therapy produced by surgically implanted catheters containing local resistive heating elements. Changes in local tumor blood flow were assessed indirectly from an algorithm based on the bioheat transfer equation. The algorithm used the ratio of catheter power to catheter temperature rise to estimate regional blood perfusion. Local heat therapy produced consistent reductions in local apparent perfusion. Changes in apparent regional perfusion occurred in intriguing patterns that gave clues to possible vascular events of therapeutic significance.

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Endothelial Superoxide Production In The Isolated Rat Heart During Early Reperfusion After Ischemia -- A Histochemical Study, Charles F. Babbs, Meloney D. Cregor, John J. Turek, Stephen F. Badylak Jan 1991

Endothelial Superoxide Production In The Isolated Rat Heart During Early Reperfusion After Ischemia -- A Histochemical Study, Charles F. Babbs, Meloney D. Cregor, John J. Turek, Stephen F. Badylak

Weldon School of Biomedical Engineering Faculty Publications

This paper describes a histochemical study of superoxide generation in buffer-perfused, isolated rat hearts during the first 2 minutes of reperfusion after 60 minutes of warm ischemia. Superoxide radical production was demonstrated by a modification of Karnovsky's manganese/diaminobenzidine technique, in which superoxide oxidizes Mn++ to Mn+++ ions, which in turn oxidize diaminobenzidine to form amber, osmiophilic polymers, observable by light or electron microscopy. Isolated hearts were rendered ischemic, reperfused with oxygen equilibrated buffer containing Mn++ and diaminobenzidine, fixed by perfusion with Trump's solution, and processed for light and electron microscopy. The method consistently demonstrated evidence of superoxide generation near the …

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Methylene Blue As An Inhibitor Of Superoxide Generation By Xanthene Oxidase: A Potential New Drug For The Attenuation Of Ischemia/Reperfusion Injury, Steven C. Salaris, Charles F. Babbs, William D. Voorhees Jan 1991

Methylene Blue As An Inhibitor Of Superoxide Generation By Xanthene Oxidase: A Potential New Drug For The Attenuation Of Ischemia/Reperfusion Injury, Steven C. Salaris, Charles F. Babbs, William D. Voorhees

Weldon School of Biomedical Engineering Faculty Publications

Tissue oxidases, especially xanthine oxidase, have been proposed as primary sources of toxic oxygen radicals in many experimental models of disease states. Among these, ischemia-reperfusion injury may be of the greatest clinical interest. In this paper we propose the use of methylene blue as a means of suppressing the production of superoxide radicals, O2, by acting as an alternative electron acceptor for xanthine oxidase. Previous work has indicated that methylene blue accepts electrons from xanthine oxidase at the iron-sulfur center. Initial experiments in our laboratory demonstrated that (1) pairs of electrons from each enzymatic oxidation are transferred to methylene blue, …

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Effective Estimation And Computer Control Of Minimum Tumour Temperature During Conductive Interstitial Hyperthermia, J A. Deford, Charles F. Babbs, U H. Patel, M W. Bleyer, J A. Marchosky, C J. Moran Jan 1991

Effective Estimation And Computer Control Of Minimum Tumour Temperature During Conductive Interstitial Hyperthermia, J A. Deford, Charles F. Babbs, U H. Patel, M W. Bleyer, J A. Marchosky, C J. Moran

Weldon School of Biomedical Engineering Faculty Publications

The goal of heat therapy in the treatment of malignant disease is to raise the temperature of all neoplastic tissue to a cytotoxic temperature for a predetermined period of time. This seemingly simple task has proved difficult in-vivo, in part because of nonuniform power absorption and in part because of nonhomogeneous and time varying tumour blood flow. We have addressed this difficulty first by utilizing the conceptually simple technique of conductive interstitial hyperthermia, in which the tumour is warmed by multiple, electrically heated catheters, and second by implementing on-line conu·ol of minimum tumour temperatures near each catheter, estimated on the …

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Design And Evaluation Of Closed-Loop Feedback Control Of Minimum Temperatures In Human Intracranial Tumors Treated With Interstitial Hyperthermia, J A. Deford, Charles F. Babbs, U H. Patel, N E. Fearnot, J A. Marchosky, C J. Moran Jan 1991

Design And Evaluation Of Closed-Loop Feedback Control Of Minimum Temperatures In Human Intracranial Tumors Treated With Interstitial Hyperthermia, J A. Deford, Charles F. Babbs, U H. Patel, N E. Fearnot, J A. Marchosky, C J. Moran

Weldon School of Biomedical Engineering Faculty Publications

The dynamic nature of blood flow during hyperthermia therapy has made the control of minimum tumor temperature a difficult task. This paper presents initial studies of a novel approach to closed-loop control of local minimum tissue temperatures utilizing a newly developed estimation algorithm for use with conductive interstitial heating systems. The local minimum tumor temperature is explicitly estimated from the power required to maintain each member of an array of electrically heated catheters at a known temperature, in conjunction with a new bioheat equation-based algorithm to predict the ‘droop’ or fractional decline in tissue temperature between heated catheters. A closed …

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Simulation Of Free Radical Reactions In Biology And Medicine: A New Two-Compartment Kinetic Model Of Intracellular Lipid Peroxidation, Charles F. Babbs, Melissa Gale Steiner Jan 1990

Simulation Of Free Radical Reactions In Biology And Medicine: A New Two-Compartment Kinetic Model Of Intracellular Lipid Peroxidation, Charles F. Babbs, Melissa Gale Steiner

Weldon School of Biomedical Engineering Faculty Publications

To explore mechanisms of free radical reactions leading to intracellular lipid peroxidation in living systems, we developed a computational model of up to 109 simultaneous enzymatic and free radical reactions thought to be involved in the initiation, propagation, and termination of membrane lipid peroxidation. Rate constants for the various reactions were obtained from the published literature. The simulation model included a lipid membrane compartment and an aqueous cytosolic compartment, between which various chemical species were partitioned. Lipid peroxidation was initiated by the iron-catalyzed, superoxide-driven Fenton reaction. A "C"-language computer program implemented numerical solution of the steady-state rate equations for concentrations …

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A Pressure Sensitive Mat For Measuring Contact Pressure Distributions Of Patients Lying On Hospital Beds, Charles F. Babbs, Joe D. Bourland, George P. Graber, James T. Jones, William E. Schoenlein Jan 1990

A Pressure Sensitive Mat For Measuring Contact Pressure Distributions Of Patients Lying On Hospital Beds, Charles F. Babbs, Joe D. Bourland, George P. Graber, James T. Jones, William E. Schoenlein

Weldon School of Biomedical Engineering Faculty Publications

The authors describe a novel system for sensing and displaying the distribution of contact pressure caused by a patient's lying on a hospital bed. The system includes a flexible, pressure sensitive mat, electronics to activate the mat, a small computer to process data, and a color video display. The present prototypes can sense pressure at 1,536 discrete locations in a rectangular grid of 24 x 64 nodes, each node representing an area of 4 cm2. The computer receives data from each node and displays the results as a false-color map, refreshable every 5 seconds. The pressure sensitive mat itself includes …

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Quantitation Of The Hydroxyl Radical By Reaction With Dimethyl Sulfoxide, Melissa G. Steiner, Charles F. Babbs Jan 1990

Quantitation Of The Hydroxyl Radical By Reaction With Dimethyl Sulfoxide, Melissa G. Steiner, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

This investigation was conducted to validate the use of dimethyl sulfoxide (DMSO) as a quantitative molecular probe for the generation of hydroxyl radicals (HO) in aqueous systems. Reaction of HO with DMSO produces methane sulfinic acid as a primary product, which can be detected by a simple calorimetric assay. To evaluate this method for estimating total HO production, we studied three model systems, including the Fenton reaction,  irradiation of water, and ultraviolet photolysis of hydrogen peroxide, for which the theoretical maximum yield of HO could be calculated and compared to measured DMSO oxidation. The results confirm that 0.05 to …

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Free Radicals And The Etiology Of Colon Cancer, Charles F. Babbs Jan 1990

Free Radicals And The Etiology Of Colon Cancer, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

This hypothesis paper reviews diverse evidence suggesting that intracolonic production of oxygen radicals may play a role in carcinogenesis. The hypothesis began to evolve when the author made the chance discovery that 1/10,000 dilutions of feces generated detectable quantities of highly reactive hydroxyl radicals (HO). The rate of HO formation, detected using DMSO as a molecular probe, was quite remarkable, corresponding to that which would be produced by over 10,000 rads of gamma irradiation per day, absorbed in the periphery of the fecal mass adjacent to the mucosa. The relatively high concentrations of iron in feces, together with the ability …

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Accuracy And Precision Of Computer-Simulated Tissue Temperatures In Individual Human Intracranial Tumours Treated With Interstitial Hyperthermia, J A. Deford, Charles F. Babbs, U H. Patel, N E. Fearnot, J A. Marchosky, C J. Moran Jan 1990

Accuracy And Precision Of Computer-Simulated Tissue Temperatures In Individual Human Intracranial Tumours Treated With Interstitial Hyperthermia, J A. Deford, Charles F. Babbs, U H. Patel, N E. Fearnot, J A. Marchosky, C J. Moran

Weldon School of Biomedical Engineering Faculty Publications

Accurate knowledge of tissue temperature is necessary for effective delivery of clinical hyperthermia in the treatment of malignant tumours. This report compares computer-predicted versus measured intratumoral temperatures in 11 human subjects with intracranial tumours, treated with a conceptually simple 'conductive' interstitial hyperthermia system. Interstitial hyperthermia was achieved by the use of parallel arrays of implanted, electrically heated catheters. The tissue was warmed by thermal conduction and blood convection. Simulation of intratumoral temperatures was achieved by solving a modified bioheat transfer equation on a digital computer using a finite difference method. Comparison of intratumoral temperatures from simulations and measured values differed …

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Theoretical Basis For Controlling Minimal Tumor Temperature During Interstitial Conductive Heat Therapy, Charles F. Babbs, Neal E. Fearnot, J A. Marchosky, C J. Moran, James T. Jones, T D. Plantenga Jan 1990

Theoretical Basis For Controlling Minimal Tumor Temperature During Interstitial Conductive Heat Therapy, Charles F. Babbs, Neal E. Fearnot, J A. Marchosky, C J. Moran, James T. Jones, T D. Plantenga

Weldon School of Biomedical Engineering Faculty Publications

This paper describes simulation of steady-state intratumoral temperatures achieved by a simple modality of local heat therapy: interstitial treatment with parallel arrays of warmed, conductive heating elements. During “conductive heating” power is directly deposited only in the interstitial probes. Adjacent tissue is warmed by heat conduction. Simulations of interstitial conductive heating involved solution of the bioheat transfer equation on a digital computer using a finite difference model of the treated tissue. The simulations suggest that when the complete temperature distributions for conductive interstitial hyperthermia are examined in detail, substantial uniformity of the temperature distributions is evident. Except for a thin …

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Changes In Expired End-Tidal Carbon Dioxide During Cardiopulmonary Resuscitation In Dogs: A Prognostic Guide For Resuscitation Efforts, Karl B. Kern, Arthur B. Sanders, William D. Voorhees, Charles F. Babbs, Willis A. Tacker, Gordon A. Ewy Apr 1989

Changes In Expired End-Tidal Carbon Dioxide During Cardiopulmonary Resuscitation In Dogs: A Prognostic Guide For Resuscitation Efforts, Karl B. Kern, Arthur B. Sanders, William D. Voorhees, Charles F. Babbs, Willis A. Tacker, Gordon A. Ewy

Weldon School of Biomedical Engineering Faculty Publications

Expired end-tidal carbon dioxide (PCO2) measurements made during cardiopulmonary resuscitation have correlated with cardiac output and coronary perfusion pressure when wide ranges of blood flow are included. The utility of such measurements for predicting resuscitation outcome during the low flow state associated with closed chest cardiopulmonary resuscitation remains uncertain. Expired end-tidal PCO2 and coronary perfusion pressures were measured in 15 mongrel dogs undergoing 15 min of closed chest cardiopulmonary resuscitation after a 3 min period of untreated ventricular fibrillation. In six successfully resuscitated dogs, the mean expired end-tidal PCO2 was significantly higher than that in nine nonresuscitated dogs only after …

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Scatchard Analysis Of Methane Sulfinic Acid Production From Dimethyl Sulfoxide: A Method To Quantify Hydroxyl Radical Formation In Physiologic Systems, Charles F. Babbs, David W. Griffin Jan 1989

Scatchard Analysis Of Methane Sulfinic Acid Production From Dimethyl Sulfoxide: A Method To Quantify Hydroxyl Radical Formation In Physiologic Systems, Charles F. Babbs, David W. Griffin

Weldon School of Biomedical Engineering Faculty Publications

A major impediment to the confirmation of free radical mechanisms in pathogenesis is a lack of direct, chemical evidence that oxygen centered free radicals actually arise in living tissues in quantities sufficient to cause serious damage. This investigation was conducted to validate the use of dimethyl sulfoxide (DMSO) as a quantitative molecular probe for the generation of hydroxyl radicals (HO*) under physiologic conditions. Reaction of HO* with DMSO produces methane sulfinic acid (MSA) as a primary product, which can be detected by a simple colorimetric assay. To develop a method for estimating total HO* production, we studied two model systems: …

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Quantitative Effects Of Iron Chelators On Hydroxyl Radical Production By The Superoxide-Driven Fenton Raction, Jean Blair Smith, Joanne C. Cusumano, Charles F. Babbs Jan 1989

Quantitative Effects Of Iron Chelators On Hydroxyl Radical Production By The Superoxide-Driven Fenton Raction, Jean Blair Smith, Joanne C. Cusumano, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

Iron bound to certain chelators is known to promote the conversion of superoxide radicals (O2) to hydroxyl radicals (HO') by the superoxide-driven Fenton reaction. The production of HO' by various iron chelates was studied using the reaction of dimethyl sulfoxide and HO' to produce methane sulphinic acid. Methane sulphinic acid was quantified by use of a simple colorimetric assay and used to determine the amounts of HO' produced. Superoxide was generated from 200 M hypoxanthine and 0.05 U/ml xanthine oxidase in the presence of 0-100 M iron and 100 M of each chelator. The results of this preliminary investigation illustrate …

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Effect Of Oxygen Concentration On The Formation Of Malondialdehyde-Like Material In A Model Of Tissue Ischemia And Reoxygenation, Steven C. Salaris, Charles F. Babbs Jan 1989

Effect Of Oxygen Concentration On The Formation Of Malondialdehyde-Like Material In A Model Of Tissue Ischemia And Reoxygenation, Steven C. Salaris, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

This study was conducted to explore the functional relationship between oxygen concentration during tissue reoxygenation after ischemia and the extent of postischemic lipid peroxidation, an indicator of reoxygenation injury. Excised rat liver or kidney tissue was rendered ischemic for 1 h at 37°C, minced into 1 mm3 fragments, and then reoxygenated for 1 h in flasks of buffered salt solution containing various amounts of oxygen. Production of malondialdehyde-like material (MDA) was measured to indicate lipid peroxidation. MDA production was minimal at oxygen tensions less than 10 mmHg, increased sharply from 10 to 50 mmHg, and plateaued at approximately 100 mmHg. …

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Lethal Hydroxyl Radical Production In Paraquat-Treated Plants, Charles F. Babbs, Jo Ann Pham, Ronald C. Coolbaugh Jan 1989

Lethal Hydroxyl Radical Production In Paraquat-Treated Plants, Charles F. Babbs, Jo Ann Pham, Ronald C. Coolbaugh

Weldon School of Biomedical Engineering Faculty Publications

Bipyridinium herbicides, including paraquat and diquat, are believed to act by generating highly reactive, oxygen-centered free radicals within chloroplasts when treated plants are exposed to sunlight. This hypothesis has not yet been confirmed by direct chemical measurements of specific free radicals. We studied paraquat-treated plants using a new method able to detect and quantify formation of highly reactive and deleterious hydroxyl radicals (HO*), in which dimethyl sulfoxide (DMSO) is used as a molecular probe. DMSO is oxidized by HO* to form the stable, nonradical compound, methane sulfinic acid, which can be easily extracted from plant tissue and measured spectrophotometrically. Initial …

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A Rapid, Widely Applicable Screen For Drugs That Suppress Free Radical Formation In Ischemia/Reperfusion, Steven C. Salaris, Charles F. Babbs Jan 1988

A Rapid, Widely Applicable Screen For Drugs That Suppress Free Radical Formation In Ischemia/Reperfusion, Steven C. Salaris, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

Substantial injury can occur during reoxygenation of previously ischemic tissue in many experimental models, as the result of the generation of oxygen-derived free radicals. To test the antiradical activity of potentially protective compounds in this setting, we developed a simple screening system, applicable to fresh biopsy specimens, in which warm ischemia and reoxygenation of excised tissue are performed in vitro. Tissue production of malondialdehyde (MDA) equivalents is used as a nonspecific-but-sensitive marker of oxygen radical damage. Test compounds with putative antiradical activity are added prior to the reoxygenation phase, and their ability to suppress MDA production is an index of …

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A Rapid, Widely Applicable Screen For Drugs That Suppress Free Radical Formation In Ischemia/Reperfusion, Steven C. Salaris, Charles F. Babbs Jan 1988

A Rapid, Widely Applicable Screen For Drugs That Suppress Free Radical Formation In Ischemia/Reperfusion, Steven C. Salaris, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

Substantial injury can occur during reoxygenation of previously ischemic tissue in many experimental models, as the result of the generation of oxygen-derived free radicals. To test the antiradical activity of potentially protective compounds in this setting, we developed a simple screening system, applicable to fresh biopsy specimens, in which warm ischemia and reoxygenation of excised tissue are performed in vitro. Tissue production of malondialdehyde (MDA) equivalents is used as a nonspecific-but-sensitive marker of oxygen radical damage. Test compounds with putative antiradical activity are added prior to the reoxygenation phase, and their ability to suppress MDA production is an index of …

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Myocardial Perfusion Pressure: A Predictor Of 24hour Survival During Prolonged Cardiac Arrest In Dogs, Karl B. Kern, Gordon A. Ewy, William D. Voorhees, Charles F. Babbs, Willis A. Tacker Jan 1988

Myocardial Perfusion Pressure: A Predictor Of 24hour Survival During Prolonged Cardiac Arrest In Dogs, Karl B. Kern, Gordon A. Ewy, William D. Voorhees, Charles F. Babbs, Willis A. Tacker

Weldon School of Biomedical Engineering Faculty Publications

Myocardial perfusion pressure, defined as the aortic diastolic pressure minus the right atria1 diastolic pressure, correlates with coronary blood flow during cardiopulmonary resuscitation (CPR) and predicts initial resuscitation success. Whether this hemodynamic parameter can predict 24-h survival is not known. We examined the relationship between myocardial perfusion pressure and 24-h survival in 60 dogs that underwent prolonged (20 min) ventricular fibrillation and CPR. Forty-two (70%) animals were initially resuscitated and 20 (33%) survived for 24 h. Myocardial perfusion pressure was significantly greater when measured at 5, 10, 15 and 20 min of ventricular fibrillation in the resuscitated animals than in …

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Colorimetric Assay For Methanesulfinic Acid In Biological Samples, Charles F. Babbs, Melissa J. Gale Jan 1987

Colorimetric Assay For Methanesulfinic Acid In Biological Samples, Charles F. Babbs, Melissa J. Gale

Weldon School of Biomedical Engineering Faculty Publications

We describe a simple colorimetric method to measure 30 to 300 M concentrations of sulfinic acids in biologic samples. The procedure employs the coupling reaction of an aromatic diazonium salt (Ar-N=N+) with the sulfinic acids (RSOOH) to produce a colored diazosulfone derivative (Ar-N=N-SOOR), which can be selectively extracted into an organic solvent. Linearity and noninterference by liver homogenate, phenols, amines, and thousand-fold or greater excesses of sulfate, thiol, and dimethyl sulfoxide are demonstrated. Sensitivity of the method is about 10 nmol per sample. Because methanesulfinic acid is the principal product of the action of hydroxyl radicals upon dimethyl sulfoxide, and …

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