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Weldon School of Biomedical Engineering Faculty Publications

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Full-Text Articles in Biomedical Engineering and Bioengineering

Optimizing Chest Compression To Rescue Ventilation Ratios During One-Rescuer Cpr By Professionals And Lay Persons: Children Are Not Just Little Adults, Charles F. Babbs, Vinay Nadkarni Jan 2004

Optimizing Chest Compression To Rescue Ventilation Ratios During One-Rescuer Cpr By Professionals And Lay Persons: Children Are Not Just Little Adults, Charles F. Babbs, Vinay Nadkarni

Weldon School of Biomedical Engineering Faculty Publications

Objective: To estimate the optimum ratio of chest compressions to ventilations for onerescuer CPR that maximizes systemic oxygen delivery in children. Method: Equations describing oxygen delivery and blood flow during CPR as functions of the number of compressions and the number of ventilations delivered over time were adapted from the former work of Babbs and Kern. These equations were solved explicitly as a function of body weight, using scaling algorithms based upon principles of developmental anatomy and physiology. Results: The optimal compression to ventilation (C/V) ratios for infants and younger children increase sharply as a function of body weight. Optimal …

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Meta-Analysis Of Two-Treatment Clinical Trials Including Both Continuous And Dichotomous Results, Charles F. Babbs Jan 2004

Meta-Analysis Of Two-Treatment Clinical Trials Including Both Continuous And Dichotomous Results, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

To expedite the timely creation of medical practice guidelines, a meta-analytic method was developed to combine of both dichotomous survival data and continuous physiologic data from multiple studies comparing the same innovative clinical intervention to standard care. The method is adapted for synthesis of small, early studies of novel treatments. An aggregate ratio, R*, of the observed treatment effect to a clinically optimal treatment effect for studies in a series is computed, and compared to the 95% confidence limit for R* under the null hypothesis. Weights assigned to each study may reflect its precision, quality, or clinical relevance. Input data …

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Simplified Meta-Analysis Of Clinical Trials In Resuscitation, Charles F. Babbs Jan 2003

Simplified Meta-Analysis Of Clinical Trials In Resuscitation, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

Objective: To present and demonstrate a new simplified method for synthesizing results of multiple clinical trials in resuscitation research. Methods: The mean difference across studies in the proportion of favorable outcomes between experimental and control groups is calculated. This difference is shown to have a t-distribution. Its significance can be ascertained with a simple t-test. The analysis can be implemented in a one-page computer spreadsheet. Results: Simplified meta-analysis provides high sensitivity and can be extended to include weighting of studies according to size or quality, comparison of subgroups of studies, tests for outliers, and calculation of the power of the …

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Interposed Abdominal Compression Cpr: A Comprehensive Evidence Based Review, Charles F. Babbs Jan 2003

Interposed Abdominal Compression Cpr: A Comprehensive Evidence Based Review, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

Interposed abdominal compression (IAC)-CPR includes all steps of standard external CPR with the addition of manual mid-abdominal compressions in counterpoint to the rhythm of chest compressions. IAC-CPR can increase blood flow during CPR about two fold compared to standard CPR without IAC, as shown by 6 of 6 studies in computer models and 19 of 20 studies in various animal models. The addition of IAC has clinical benefit in humans, as indicated in 10 of 12 small to medium sized clinical studies. The technique increases the frequency of immediate return of spontaneous circulation for in-hospital resuscitations from roughly 25% to …

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Optimum Compression To Ventilation Ratios In Cpr Under Realistic, Practical Conditions: A Physiological And Mathematical Analysis, Charles F. Babbs, Karl B. Kern Jan 2002

Optimum Compression To Ventilation Ratios In Cpr Under Realistic, Practical Conditions: A Physiological And Mathematical Analysis, Charles F. Babbs, Karl B. Kern

Weldon School of Biomedical Engineering Faculty Publications

Objective: To develop and evaluate a practical formula for the optimum ratio of compressions to ventilations in CPR. The optimum value of a parameter is that for which a desired result is maximized. Here the desired result is assumed to be either oxygen delivery to peripheral tissues or a combination of oxygen delivery and waste product removal. Method: Equations describing oxygen delivery and blood flow during CPR as functions of the number of compressions and the number of ventilations delivered over time were developed from principles of classical physiology. These equations were solved explicitly in terms of the compression/ventilation ratio …

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Circulatory Adjuncts: Newer Methods Of Cardiopulmonary Resuscitation, Charles F. Babbs Jan 2002

Circulatory Adjuncts: Newer Methods Of Cardiopulmonary Resuscitation, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

Current standard CPR only provides about one fifth of normal forward blood flow and only about one quarter of the blood flow that is theoretically possible with advanced external techniques. Two such techniques are now approved as optional alternatives in resuscitation guidelines. This chapter reviews modern understanding of the physiology of blood flow during CPR and practical aspects of utilizing more advanced resuscitation methods. When properly performed these methods produce statistically significant increases in survival.

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Biomechanics Of Heading A Soccer Ball: Implications For Player Safety, Charles F. Babbs Jan 2001

Biomechanics Of Heading A Soccer Ball: Implications For Player Safety, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

To better understand the risk and safety of heading a soccer ball, the author created a set of simple mathematical models based upon Newton’s second law of motion to describe the physics of heading. These models describe the player, the ball, the flight of the ball before impact, the motion of the head and ball during impact, and the effects of all of these upon the intensity and the duration of acceleration of the head. The calculated head accelerations were compared to those during presumably safe daily activities of jumping, dancing, and head nodding and also were related to established …

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Consensus Evidence Evaluation In Resuscitation Research: Analysis Of Type I And Type Ii Errors, Charles F. Babbs Jan 2001

Consensus Evidence Evaluation In Resuscitation Research: Analysis Of Type I And Type Ii Errors, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

Objective: This paper addresses the following statistical question: ‘if genuine improvements in cardiopulmonary resuscitation (CPR) were discovered that doubled the probability of resuscitation success in a series of randomized clinical trials, would they be recognized and incorporated into consensus guidelines?’ Methods: Statistical powers for hypothetical individual clinical trials comparing experimental and control CPR were computed as a function of the study N when the true probabilities for immediate survival, 24 h survival, and discharge survival in the experimental group were twice those in the control group. Next, the binomial distributions describing the numbers of statistically significant studies in a series …

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Efficacy Of Interposed Abdominal Compression-Cardiopulmonary Resuscitation (Cpr), Active Compression And Decompression-Cpr, And Lifestick Cpr: Basic Physiology In A Spreadsheet Model, Charles F. Babbs Jan 2000

Efficacy Of Interposed Abdominal Compression-Cardiopulmonary Resuscitation (Cpr), Active Compression And Decompression-Cpr, And Lifestick Cpr: Basic Physiology In A Spreadsheet Model, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

This study was undertaken to understand and predict results of experimental cardiopulmonary resuscitation (CPR) techniques involving compression and decompression of either the chest or the abdomen. Simple mathematical models of the adult human circulation were used. Assumptions of the models are limited to normal human anatomy and physiology, the definition of compliance (volume change/pressure change), and Ohm’s law (flow = pressure / resistance). Interposed abdominal compression-CPR, active compression and decompression of the chest, and Lifestick CPR, which combines interposed abdominal compression and active compression and decompression, produce, respectively, 1.9-, 1.2-, and 2.4- fold greater blood flow than standard CPR and …

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Mechanics Of Cpr Performed With The Patient On A Soft Bed Versus A Hard Surface, John M. Boe, Charles F. Babbs Jan 1999

Mechanics Of Cpr Performed With The Patient On A Soft Bed Versus A Hard Surface, John M. Boe, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

Objective: To study the effects of underlying bed softness versus stiffness on the effectiveness of chest compressions in CPR. Methods: For a wide range of bed stiffness constants, mathematical models describing compression of the human chest supported by a hospital bed were created for an adult thorax experiencing either a sinusoidal compressive force or a sinusoidal sternal displacement. Results: With 5 cm peak displacement, sternum-to-spine compression fell from 4.3 to 1.0 cm, and peak power fell from 59 to 23 Watts, as bed stiffness decreased from 50,000 to 5,000 N/m. Less than 35% of maximal chest compression occurred at a …

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Multiresolution Detection Of Spiculated Lesions In Digital Mammograms, Sheng Liu, Charles F. Babbs, Edward Delp Jan 1998

Multiresolution Detection Of Spiculated Lesions In Digital Mammograms, Sheng Liu, Charles F. Babbs, Edward Delp

Weldon School of Biomedical Engineering Faculty Publications

In this paper we present a novel multiresolution scheme for the detection of spiculated lesions in digital mammograms. First, a multiresolution representation of the original mammogram is obtained using a linear phase nonseparable 2-D wavelet transform. A set of features is then extracted at each resolution in the wavelet pyramid for every pixel. This approach addresses the difficulty of predetermining the neighborhood size for feature extraction to characterize objects that may appear in different sizes. Detection is performed from the coarsest resolution to the finest resolution using a binary tree classifier. This top-down approach requires less computation by starting with …

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Preliminary Results Of Deferoxamine And L1 Treatment Of Spinal Cord Ischemia, David G. Reuter, Willis A. Tacker Jr, Charles F. Babbs, Stephen F. Badylak, William D. Voorhees, Peter E. Konrad Jan 1995

Preliminary Results Of Deferoxamine And L1 Treatment Of Spinal Cord Ischemia, David G. Reuter, Willis A. Tacker Jr, Charles F. Babbs, Stephen F. Badylak, William D. Voorhees, Peter E. Konrad

Weldon School of Biomedical Engineering Faculty Publications

No abstract provided.

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Theoretically Optimal Duty Cycles For Chest And Abdominal Compression During External Cardiopulmonary Resuscitation, Charles F. Babbs, Keir Thelander Jan 1995

Theoretically Optimal Duty Cycles For Chest And Abdominal Compression During External Cardiopulmonary Resuscitation, Charles F. Babbs, Keir Thelander

Weldon School of Biomedical Engineering Faculty Publications

Objective: To use an electronic model of human circulation to compare the hemodynamic effects of different durations of chest compression during external CPR, both with, and without interposed abdominal compression (IAC). Methods: An electrical analog model of human circulation was studied on digital computer workstations using SPICE, a general-purpose circuit simulation program. In the model the heart and blood vessels were represented as resistive-capacitive networks, pressures as voltages, blood flow as electric current, blood inertia as inductance, and cardiac and venous valves as diodes. External pressurization of the heart and great vessels, as would occur in IAC-CPR, was simulated by …

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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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The Evolution Of Abdominal Compression In Cardiopulmonary Resuscitation, Charles F. Babbs Jan 1994

The Evolution Of Abdominal Compression In Cardiopulmonary Resuscitation, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

Objective: To review the history of external abdominal compression as an adjunct to cardiopulmonary resuscitation (CPR), tracking the development of five major themes over the course of the 20th century: 1) augmentation of peripheral resistance by physical means, 2) risk of hepatic injury with abdominal compression, 3) counterpulsation vs. sustained compression, 4) the abdominal pump mechanism, and 5) contact compression techniques. Methods: Literature retrieved from successive MEDLINE English-language searches was reviewed with a special emphasis on work and concepts highlighted by participants at the First Purdue Conference on Interposed Abdominal Compression-CPR, September 1992. Results: External abdominal compression of one form …

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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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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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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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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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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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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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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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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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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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