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Biomedical subjects

M B Smith

Publications and source records attributed to M B Smith.

At least 127 records · Page 7Linked to original sources
PubMed1989

In vivo functioning of creatine phosphokinase in human forearm muscle, studied by 31P NMR saturation transfer.

31P nuclear magnetic resonance (NMR) saturation transfer has been used to measure enzymatic flux through the creatine phosphokinase reaction in the direction of ATP synthesis in the human forearm muscle flexor digitorum superficialis. Modification of the ratio method for measurement of spin-lattice relaxation (R. Freeman, H.D.W. Hill, and R. Kaptein, J. Magn. Reson. 7, 82(1972]was tested and used to appreciably shorten the duration of the measurement. Under conditions of steady state work intracellular pH decreased slightly by 0.06 units and the spin-lattice relaxation time of phosphocreatine in muscle was unchanged, while flux from phosphocreatine to ATP was 64 +/- 10% of the resting value. This is contrary to the increase in flux of 155% predicted from previous saturation transfer studies carried out in vitro on rabbit skeletal muscle creatine phosphokinase using metabolite concentrations to mimic those in vivo (E.A. Shoubridge, J.L. Bland, and G.K. Radda, Biochim. Biophys. Acta 805, 72 (1984]. This discrepancy could be accounted for by an underestimation of the ADP concentrations to which the enzyme is exposed due to inaccurate assumptions about the total metabolite concentrations, or possibly by compartmentation of creatine phosphokinase and its reactants.

Adenosine Diphosphate↗
PubMed1989

Mycetoma of the hand.

Mycetoma or maduromycosis is a rare chronic granulomatous disease caused by a fungus infection. We report a rare case of mycetoma in the hand; to our knowledge this is the first report in the United States of mycetoma caused by Nocardia asteroides. The patient had had 2 years of chronic drainage and edema of the left hand after a penetrating injury sustained in the shipyards. After surgical debridement he was treated with co-triamazole, 1 tablet orally four times a day for 6 months. The chronic drainage has ceased but most of his wrist and hand joint movements are restricted.

Hand↗
PubMed1989

Anaphylactoid reaction to chymopapain.

Chymopapain is a proteolytic enzyme used in the chemonucleolysis of the herniated nucleus pulposus of lumbar intervertebral discs. It causes rapid hydrolysis of the noncollagenous polypeptides that maintain the tertiary structure of the chondromucoprotein of the nucleus pulposus. We report here an anaphylactoid reaction after the intervertebral injection of chymopapain.

Adult↗
PubMed1989

Cerebral blood flow measured by NMR indicator dilution in cats.

We developed techniques to assess the utility of a nuclear magnetic resonance (NMR) indicator for cerebral blood flow studies in cats, using Freon-22 for the first candidate. A PIN-diode-switched NMR experiment allowed the acquisition of an arterial as well as a cerebral fluorine-19 signal proportional to concentration vs. time in a 1.89 T magnet. Mean +/- SD blood:brain partition coefficients for Freon-22 were estimated at 0.93 +/- 0.08 for gray matter and 0.77 +/- 0.12 for white matter. Using maximum-likelihood curve fitting, estimates of mean +/- SD resting cerebral blood flow were 50 +/- 19 ml/100 g-min for gray matter and 5.0 +/- 2.0 ml/100 g-min for white matter. Hypercapnia produced the expected increases in gray and white matter blood flow. The physiologic effects of Freon-22, including an increase in cerebral blood flow itself with administration of 40% by volume, may limit its use as an indicator. Nevertheless, the NMR techniques described demonstrate the feasibility of fluorine-19-labeled compounds as cerebral blood flow indicators and the promise for their use in humans.

Animals↗
PubMed1989

A path analysis of an adolescent drinking behavior model derived from problem behavior theory.

The interrelationships between composite variables comprised of demographics, socialization, personality, perceived environment, conventional and problem behaviors, and their combined mediational influences on adolescent drinking behavior are examined. Students randomly sampled from four suburban, metropolitan-area high schools (N = 499) were administered the 250-question Survey of Underage Drinking Styles. All 12 composite variables, derived from the survey, were arranged in a causal model and submitted to a confirmatory path analysis. Data were analyzed by multiple regression procedures. According to the present model, a powerful pathway through to drinking may begin with family interaction problems, which may lead to a reduction in the adolescent's social coping skills. A reduction in the adolescent's coping skills may lead to a compensatory belief that alcohol improves mental and physical functions and an increased affiliation with and acceptance of the peer group's attitude and behavior toward consuming alcohol as a replacement coping skill. The adolescent's drinking may then increase as a result of the affiliative need to conform to peer group pressure.

Adolescent↗
PubMed1989

Differentiation and treatment of hemangiomas and arteriovenous malformations.

Confusion exists about the differentiation of hemangiomas and other congenital vascular anomalies although they are the most common type of birth defect. During the past 10 years, these lesions have been reclassified on a pathophysiological basis which assists in defining their prognosis and treatment. Hemangiomas are broken down into three categories, those which affect the afferent capillary bed and may involute, efferent venous or lymphatic lesions which grow with the patient, and progressively growing vascular hamartomas which affect both venous and arterial limbs of the circulation and may threaten with limb loss or congestive heart failure. The afferent-efferent lesions require a multidisciplinary approach with close follow-up for their successful management.

Arteriovenous Malformations↗
PubMed1988

Prolonged deterioration of ischemic brain energy metabolism and acidosis associated with hyperglycemia: human cerebral infarction studied by serial 31P NMR spectroscopy.

We report on a patient with a large ischemic hemispherical stroke studied serially by 31P nuclear magnetic resonance spectroscopy. Persistent hyperglycemia was associated with prolonged acidosis in ischemic brain and failure of high-energy phosphate metabolism to recover. These in vivo human data support the concept that hyperglycemia adversely affects ischemic brain metabolism, pH, and clinical outcome.

Acidosis↗
PubMed1988

Some Navajo Indian opinions about alcohol abuse and prohibition: a survey and recommendations for policy.

In this study a questionnaire was administered to a sample of Navajo Indians in the southwestern region of the reservation to examine (1) their knowledge about the consequences of alcohol abuse and (2) their opinions about alcohol abuse, the etiology of abuse and alcohol legalization. Survey responses indicate that the Navajo surveyed are quite knowledgeable about the various adverse consequences of alcohol abuse. The survey found that 52% of these Navajo adults currently drink at all, and the opinion responses generally characterize alcohol consumption, even in small amounts, as a negative behavior. Sixty-three percent of all Navajos agreed with the popular, but scientifically unsubstantiated, belief that Indians have a physical weakness to alcohol that non-Indians do not have. Alcohol legalization on the reservation is opposed by 81% of the Navajos surveyed. Opinions about alcohol use and policy do not vary greatly even when knowledge of alcohol consequences and current drinking status is considered. The article concludes with a discussion of the importance of positive, solution-oriented public education and debate for entertaining new ideas about alcohol policy and for reducing the sequelae of alcohol abuse among the Navajo.

Adolescent↗
PubMed1988

Smoking and inflammatory bowel disease in families.

Smoking habits of inflammatory bowel disease (IBD) patients were compared with family members with IBD to determine the effects of cigarette smoking on the development of either ulcerative colitis or Crohn's disease. In a previous study of patients randomly selected from the University of Chicago IBD Registry, 40 patients with IBD were identified as having a confirmed IBD family history. Thirty-one of those probands and relatives were contacted and included in this study. Of the 36 patients in the study with Crohn's disease, 78% were former or current smokers, whereas only 27% of the 26 patients with ulcerative colitis were former or current smokers. Eighty-three percent of all those who had ever smoked, started before the onset of symptoms of their disease. There were high concordance rates for type of IBD (81%) and for smoking habits (65%, when a history of smoking was compared with a history of never having smoked) among the matched pairs. The concordance rates were not significantly different from each other, but the magnitude of concordance of each suggests that both smoking habits and consanguinity may be important factors in the pathogenesis of this disease.

Adult↗
PubMed1987

The development of a pH-sensitive contrast agent for NMR 1H imaging.

Fe(III)meso-tetra(4-sulfonatophenyl)porphine (Fe-TPPS4) has been investigated as a potential pH-sensitive nuclear magnetic resonance (NMR) proton image contrast agent. Relaxation rates (1/T1 and 1/T2) of water protons were measured as a function of pH and concentration of Fe-TPPS4 in phosphate-buffered isotonic saline. Transverse relaxation rates (1/T2) did not change appreciably with pH above 6.0. Longitudinal relaxation rates (1/T1) increased significantly between pH 7.75 and 5.75. This effect was more pronounced with the increasing concentration of Fe-TPPS4 from 0.1 to 1.5 mM and is attributed to a pH-dependent equilibrium between the high-spin (S = 5/2) Fe-TPPS4 monomer at low pH and the antiferromagnetically coupled mu-oxodimer O-(FeTPPS4)2 at high pH. The efficacy of this pH-dependent contrast agent is demonstrated in vitro.

Contrast Media↗
PubMed1987

Benefits of high-dose dopamine in experimental neonatal septic shock.

The benefits of dopamine resuscitation in neonatal shock are in doubt. To evaluate dopamine's effectiveness on regional perfusion and survival, neonatal pigs were subjected to fecal Escherichia coli peritonitis-induced septic shock and were randomly divided into equal groups. Control animals (Group I) were not resuscitated with dopamine. Dopamine resuscitation, as a continuous infusion of 5 micrograms/kg/min (Group II), 50 micrograms/kg/min (Group III), or 200 micrograms/kg/min (Group IV), began when cardiac output dropped 20% below baseline. Radiolabeled microspheres were used to assess regional perfusion. Survival was defined as no hemodynamic compromise at 24 hr. Increased survival time correlated with sustained increases in cardiac output and blood pressure in Group III, which were not observed in the other groups. Significant changes in multiorgan regional perfusion were also observed in Group III and correlate with the improved survival. These data suggest that higher than usual doses of dopamine may be beneficial in neonates with peritonitis-induced septic shock.

Animals↗