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Biomedical subjects

D S Young

Publications and source records attributed to D S Young.

At least 19 recordsLinked to original sources
PubMed1992

How do somersaulters land on their feet?

Body movements of trampolinists landing upright from forward somersaults, with eyes open and closed, were analyzed to test a theory of how braking and timing of actions are conjointly controlled. In regulating landing, rotation has to be slowed by extending the body so that it reaches the upright just as the feet hit the trampoline. Extending a theory of visual control of linear braking, it was hypothesized that upright landing is achieved by perceptually regulating body extension so as to keep the ratio angle of body to upright: rate of change of angle (the tau function of the angle) proportional to time-to-landing. The data support the hypothesis, indicate that vision improves precision of control, and argue further for the value of the tau function in the perceptual regulation of action.

Attention↗
PubMed1992

Two-dimensional electrophoresis of urine specimens from patients with renal disease.

In an effort to develop non-invasive markers capable of characterizing renal disease with greater sensitivity and specificity than those currently available, urinary proteins were studied by high-resolution two-dimensional electrophoresis in order to catalog those proteins which appeared to be most affected by a variety of renal diseases. Urine specimens were prepared by high-pressure liquid chromatography and subjected to two-dimensional gel electrophoresis. Proteins were visualized with silver stain. Gels from 17 patients were analyzed in detail and compared to standard maps of human urinary proteins and plasma. The two-dimensional gels displayed approximately 100 times the number of proteins demonstrated by high resolution agarose electrophoresis. We have identified 34 proteins whose urinary concentrations were most affected by renal disease. Twenty seven were of plasma origin, based upon comigration with plasma samples (17 of unknown identity and function). Seven proteins were observed in normal urine but not present in plasma. These proteins, which may represent kidney tissue proteins, were not apparent in the urine of patients with proteinuria, most likely due to dilutional effects.

Biomarkers↗
PubMed1992

Pharmacodynamics and pharmacokinetics of cyclosporin A in the newborn pig.

The disposition kinetics of cyclosporin A in the neonates as well as age-related differences in lymphocyte responses to cyclosporin A are unknown. A single intravenous infusion of cyclosporin A was given to neonatal (2.5 or 5 mg/kg) and mature pigs (10 mg/kg) and blood cyclosporin A levels were measured by RIA. The neonates had longer elimination half-life and lower drug clearance than mature animals. Suppression in lymphocyte proliferation was only observed in mixed lymphocyte reaction and phytohemagglutinin-stimulated cultures of the 2-hour samples from neonates receiving 5 mg/kg. We conclude that neonatal pig exhibit different cyclosporin A pharmacokinetics and show higher sensitivity to cyclosporin A than mature animals.

Aging↗
PubMed1992

Determination and validation of reference intervals.

A brief overview of the concept of the reference interval and its application in medical practice is presented. The populations from whom it is possible to derive reference intervals are discussed. Procedures used to develop reference intervals from both a selected healthy population and from hospitalized patients are discussed, and the influence of statistical method on presented reference intervals is reviewed. However, the weakness of using a reference interval derived from a population of individuals to facilitate interpretation of test results is illustrated in relationship to the variability of test results within an individual. In spite of the efforts that are made within the clinical laboratory through development of reference intervals to provide maximum guidance to clinicians to facilitate their proper interpretation of test values in patients, it is apparent that much of the carefully derived scientific information is ignored in actual practice.

Data Interpretation, Statistical↗
PubMed1989

The effect of applied chest compression force on systemic arterial pressure and end-tidal carbon dioxide concentration during CPR in human beings.

Twelve adult (nine men and three women) cardiac arrest patients were studied as they received CPR by a computerized Thumper to determine the influence of the applied chest compression force on blood flow (as assessed by the end-tidal carbon dioxide concentration) and arterial pressure. At the end of a resuscitation when the decision was made by the senior physician to cease resuscitative efforts, the applied force on the CPR Thumper was decreased from 140 to 0 pound-force (lbf) in 20-lbf increments at 30-second intervals. Radial artery cutdown blood pressure and end-tidal carbon dioxide (ETCO2) were recorded continuously. Arterial systolic blood pressure was linearly related (r = .59, P less than .0001) to applied force (systolic blood pressure, 31 +/- 6 mm Hg at 20 lbf to 60 +/- 7 mm Hg at 140 lbf). ETCO2 (r = .42, P less than .0001) was also linearly related to applied force (ETCO2, 0.7 +/- 0.1% at 20 lbf to 1.5 +/- 0.2% at 140 lbf). Diastolic pressure did not change significantly with change in applied force (17 +/- 2 mm Hg from 20 to 140 lbf). Our findings indicate that higher compression force than that currently recommended may improve arterial systolic pressure and flow in human beings receiving closed-chest compression during CPR.

Blood Pressure↗
PubMed1989

Dose-dependent vasopressor response to epinephrine during CPR in human beings.

The optimal dose of epinephrine during CPR in human beings is unknown. We studied ten prehospital cardiac arrest patients (six men and four women; mean age, 54 +/- 5 years) to determine the vasopressor response and change in the end-tidal carbon dioxide concentration (PetCO2) after incremental (1-, 3-, and 5-mg) doses of IV epinephrine given five minutes apart during closed-chest CPR. All patients were in ventricular fibrillation on arrival of the paramedics and did not respond to standard advanced cardiac life support. CPR was performed with a computerized Thumper; all patients were intubated and ventilated at 12 times a minute at an FiO2 of 0.8. Radial artery pressure was measured with a 20 angiocath inserted by radial artery cutdown. Paramedic response time was 4.3 +/- 0.5 minutes; elapsed time to emergency department arrival was 40.0 +/- 9.5 minutes. Initial blood gases were paO2, 241 +/- 50 mm Hg; pH, 7.23 +/- 0.08; paCO2, 27 +/- 5 mm Hg; and HCO3, 11 +/- 2 mEq/L. Baseline systolic and diastolic blood pressures were 47 +/- 5 mm Hg and 18 +/- 2 mm Hg, respectively. Systolic blood pressure was directly related to the dose of epinephrine (P less than .0001), rising to 69 +/- 7 mm Hg, 74 +/- 8 mm Hg, and 85 +/- 8 mm Hg after 1-, 3-, and 5-mg doses of epinephrine, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗
PubMed1988

Quinidine-induced decrease of intracellular esterase activity in a hepatoma cell line.

Using image-analyzing equipment, we measured the effect of quinidine on the activity of naphthol AS-D chloroacetate esterase, alpha-naphthyl butyrate esterase, alpha-naphthyl acetate esterase, and acid phosphatase in individual cells of a human Hep G2 hepatoma cell line. The impact of the drug on the morphology of the cells was also observed. Depending on the concentration of quinidine applied, various changes occurred, the most extreme being cell death. However, at some drug concentrations that did not appear to affect visible cell structures, the activity of the esterases was decreased. This lessened enzyme activity did not seem to be related to the enzymes leaking from the cells, because the activity of acid phosphatase was unaffected. Inhibition of the esterase activity was related to the interval of exposure to quinidine in the perfusing medium and to the concentration of the drug. We consider the system described here to be a potential replacement for experiments with animals in the study of hepatotoxicity.

Animal Testing Alternatives↗
PubMed1986

Clinical laboratory manifestations of exposure to dioxin in children. A six-year study of the effects of an environmental disaster near Seveso, Italy.

Following a major environmental accident near Seveso, Italy, on July 10, 1976, we attempted to determine if the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) released into the atmosphere had any effect on the liver function and lipid metabolism of exposed children. From July 1976 to June 1982, we analyzed the results of more than 4500 laboratory tests (alanine aminotransferase, aspartate aminotransferase, gamma-glutamyltransferase, alkaline phosphatase, cholesterol, and triglycerides in plasma and delta-aminolevulinic acid in urine) in a population of about 1500 children aged 6 to 10 years at the moment of the accident. The children exposed to the highest concentration of TCDD showed alterations in serum gamma-glutamyltransferase and alanine aminotransferase activity compared with the control group. These differences were restricted to values inside limits set from the lower end of the normal range to slightly above it. The observed abnormalities were slight and disappeared with time.

Accidents, Occupational↗
PubMed1986

Visual control of step length during running over irregular terrain.

Running over uneven ground requires visually regulating step length to secure proper footing. To examine how this is achieved, we studied subjects running on a treadmill on a series of irregularly spaced targets. The movements of their lower limbs and coccyx relative to the targets were monitored opto-electronically by a Selspot system. The results indicated that step length was adjusted to strike the targets primarily by varying the vertical component of impulse applied to the ground during the stance phase. In contrast, horizontal impulse was not varied significantly, and changing the reach forward of the foot on landing contributed little to variation in step length. Changing the vertical impulse simply altered the step time proportionately. Thus the data are consistent with a time-based model in which vertical impulse is modulated by the optic variable delta tau (Lee, 1976) specifying the time gap that has to be bridged by the runner between two targets.

Coccyx↗
PubMed1978

SI units for clinical laboratory data.

The international System of Units (SI) has not yet been accepted by American physicians because of reluctance to convert to a new system and the corresponding need for relearning. The impetus to introduce the SI came from European laboratory scientists; the system was later accepted (not always enthusiastically) by physicians after the same objections now voiced by their US counterparts were overcome. Now that many American laboratory scientists are actively studying and assessing the benefits of SI, we may have begun the chain of events that will lead to general acceptance by physicians in the United States.

Abbreviations as Topic↗
PubMed1978

Automated monitoring of drug-test interactions.

A computer-based file of the effects of drugs on clinical laboratory tests was used in a university hospital to generate reports of all potential interactions between the drugs administered to a patient and the laboratory tests ordered on his body fluids. More than 13,000 patient days were monitored in four different nursing units. The physician users of the system indicated that automatic reporting of possible drug-test interactions had both educational and clinical value. A critical review of patient charts suggested that automatic reporting of drug-test interactions caused physicians to alter therapy in about 0.1% of instances in which a report was generated. The users themselves indicated that they altered treatment as a result of the reports in a substantially greater number of cases.

Attitude of Health Personnel↗