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Biomedical subjects

L S Cook

Publications and source records attributed to L S Cook.

52 records · Page 3Linked to original sources
PubMed1981

Selenium content and glutathione peroxidase activity in tissues of young cattle fed supplemented whole milk diets.

Three groups of 5 calves each were fed (from birth to 12 weeks of age) 3 vitamin-mineral supplemented whole milk diets differing only in their selenium (Se) content (0.03, 0.23, and 0.53 microgram/g of solids). Glutathione peroxidase (GSH-Px) activities and Se concentrations were determined in blood at weekly intervals and in selected tissues after 12 weeks. There were marked differences among the tissues in GSH-Px activity, most notably in the liver, lungs, and adrenal glands, depending on whether H2O2 or cumene hydroperoxide was used to assay the enzyme. Tissues having the highest GSH-Px activity on a weight basis, when assayed with the H2O2 substrate, were erythrocytes and testes. Enzyme activity in thymus, brain, striated muscle, adipose tissue, and blood plasma was lowest among the tissues analyzed. The Se concentration on a fresh tissue-weight basis was highest in kidney cortex, intermediate in kidney medulla, testes, liver, and spleen, and lowest in striated muscle, adipose tissue, and blood plasma. The Se concentration was increased in liver, kidney cortex, spleen, and heart, with increasing increments of dietary Se, whereas differences were not observed in testes and adipose tissue.

Animal Feed↗
PubMed1981

Distribution of selenium-dependent and nonselenium-dependent glutathione peroxidase activity in tissues of young cattle.

Separation by gel-filtration chromatography and enzyme assay with H2O2 and an organic hydroperoxide substrate were used to identify selenium (Se)-dependent and non-Se-dependent glutathione peroxidase (GSH-Px) in tissues of calves fed supplemented whole milk diets differing only in their Se content (0.03, 0.23, and 0.53 microgram/g of total solids). Spleen, cardiac muscle, erythrocytes, brain, thymus, adipose tissue, and striated muscles of calves were found to contain only the Se-dependent GSH-Px. Tissues having both enzymes included liver, lungs, adrenal glands, testes, kidney medulla, and kidney cortex. Hepatic tissue contained the highest percentage of non-Se-dependent GSH-Px activity of the calf tissues. For those tissues having Se-dependent and non-Se-dependent GSH-Px activity, the Se-dependent enzyme activity was generally lower for calves fed 0.03 microgram of Se/g of total solids as compared with activity in calves fed larger amounts of Se. The tissue ranking of non-Se-dependent GSH-Px activity, as a percentage of total GSH-Px activity, was not changed by differences in the Se content of the diets fed to the calves.

Animals↗
PubMed1980

Changes in cardiac glycoside activity produced by aminosugar addition.

In anesthetized dogs, structure activity relationships among three cardiotonic compounds were determined by comparing the cardiovascular effects of digotoxigenin (the genin) to digitoxigenin-galactose (a genin-neutral sugar combination) and to digitoxigenin-aminogalactose (ASI-222, a genin-aminosugar combination) using either bolus i.v. injections or constant i.v. infusions. We recorded the effects of these drugs upon cardiac rate, mean blood pressure, left ventricular dP/dt, cardiac index, systolic time intervals, tension-time index, therapeutic index, ventricular excitability and the ventricular refractory period. The addition of an aminosugar group to digitoxigenin or an amine group to galactose-digitoxigenin results in an agent with greater ability to reduce heart rate and to increase cardiac contractility and cardiac index without affecting the tension-time index. Moreover, the addition of an amino group significantly increased the therapeutic index and ventricular refractory period but reduced the toxic index (lethal dose/toxic dose) when compared to the neutral-sugar cardenolide and genin. Our data indicate that such a substitution confers greater potency, prolongs the duration of activity and results in a compound with a greater therapeutic index.

Amino Sugars↗
PubMed1977

Comparison of the cardiac effects of ASI-222 HCl, an aminosugar cardiac glycoside, and digoxin.

The effects of ASI-222 HCl and digoxin on cardiac contractile force, dP/dt, heart rate and mean blood pressure in the dog were evaluated following i.v. administration. Additional studies were performed on isolated, electrically driven rabbit atria with both ASI-222 and digoxin. Our data show that ASI-222 (40 microgram/kg) in non-vagotomized dogs produced a two-fold greater increase in cardiac contractile force and dP/dt than did an equimolar dose of digoxin. ASI-222 caused a peak increase in contractile force and dP/dt 10 min after administration, whereas the peak to digoxin occurred at 30 min. ASI-222 was more effective in non-vagotomized dogs in increasing contractile force and dP/dt than in vagatonized dogs. The inotropic responses to digoxin were not reduced by vagotomy. Studies on isolated electrically driven rabbit atria indicate ASI-222 to be 7-8 times more potent than digoxin in increasing contractile force. These data demonstrate that ASI-222 produces an earlier and greater increase in contractile force and dP/dt than digoxin in equimolar doses.

Aminoglycosides↗
PubMedDate not supplied

Structure-activity relationships of an aminosugar cardiac glycoside, ASI-222 HCl, in the heart-lung preparation of the dog.

ASI-222 [3-beta-O-(4-amino-4,6-dideoxy-beta-D-galactopyranosyl) digitoxigenin HCl] is a semisynthetic aminosugar cardiac glycoside that has been shown to have a greater therapeutic index than ouabain or digoxin in dogs. We have compared the effects of ASI, digitoxigenin, digitoxigenin-beta-D-galactose, and digoxin in the dog heart-lung preparation. Minute work and stroke work were calculated. Controls were obtained before and after the hearts were failed with sodium pentobarbital. ASI-222 is about three times more potent than digitoxigenin and about twice as potent as digitoxigenin-beta-D-galactose in producing similar increases in the left ventricular stroke work. ASI-222 is about three times more potent than digoxin in creasing left ventricular stroke work. Our results indicate that the addition of an aminosugar group to the genin further increased potency over that observed with the addition of a single neutral sugar and prolonged the duration of activity in failing myocardial tissue.

Aminoglycosides↗
PubMedDate not supplied

Identification of ethanol-intoxicated patients with minor head trauma requiring computed tomography scans.

OBJECTIVE: To determine whether clinical parameters and neurologic scores can be used to guide the decision to obtain computed tomography (CT) head scans for ethanol- intoxicated patients with presumed-minor head injuries. METHODS: In a prospective cohort analysis, 107 consecutive adult patients who presented to a county emergency department (ED) with serum ethanol levels >80 mg/dL and minor head trauma were studied. Commonly used clinical variables were determined for each patient. Each patient also underwent an abbreviated neurologic scoring examination and a Glasgow coma scale (GCS) score evaluation at the time of presentation and one hour later, after which a cranial CT scan was done. For purposes of analysis, patients with and patients without intracerebral injuries visible on CT scans of the head were compared. RESULTS: Nine of 107 patients (8.4%; 95% confidence interval [CI] = 3.9-15.4%) had CT scans that were positive for intracerebral injury. Two patients (1.9%; 95% CI = 0.2-6.6%) needed craniotomy. Five patients had hemotympanum and two patients had bilateral periorbital ecchymosis, but CT scans were negative for intracerebral injury in these patients. There was no statistically significant difference between the patients with and without CT scan abnormalities, based on the clinical variables, the GCS scores, or the abbreviated neurologic scoring examinations at presentation or at one hour. CONCLUSION: The prevalence of intracerebral injury in CT scans of ethanol-intoxicated patients with minor head injuries was 8.4%. Commonly used clinical parameters and neurologic scores at presentation and one hour later were unable to predict which patients would have intracerebral injuries and evidenced by CT scans. Our low (1.9%) neurosurgical intervention rate supports the need to develop a selective approach to CT scanning in this population.

Adult↗
PubMedDate not supplied

Gaining access to Native American cultures by non-Native American nursing researchers.

The authors sought to identify the problems non-Native American nurse researchers might have in gaining access to Native American cultures. The authors' method was nursing ethnography; several different tribes were observed. Findings revealed five significant categories of barriers to health care: understanding of cultural differences, language barriers, differences in interpersonal communication, historical antipathy/fear of exploitation by Native Americans, and distrust of researcher motivation. The authors make several recommendations for researchers to prepare extensively if they plan to work with Native Americans.

Anthropology, Cultural↗
PubMedDate not supplied

A simple case of anemia: pathophysiology of a common symptom.

Anemia is a common symptom associated with a variety of diseases, disorders, and dietary deficiencies. A review of hemoglobin and hematocrit levels may not be sufficient to determine the severity of the underlying problem. This article gives the reader an enhanced understanding of red cell morphology and reviews some of the common problems associated with anemia.

Anemia↗
PubMedDate not supplied

Treatment of junctional rhythm after heart transplantation with terbutaline.

Atrial and junctional arrhythmias may occur after heart transplantation. Often these arrhythmias require intravenous beta-agonists or atrial pacing to improve posttransplant hemodynamic values. We describe a heart transplant patient with a hemodynamically significant junctional rhythm who responded to oral terbutaline with conversion to sinus rhythm.

Adult↗
PubMedDate not supplied

Digitalis-sensitive Na+, K+-ATPase: lack of a direct catecholamine-mediated stimulation in bovine myocardial tissue.

It has been documented that biogenic amines can stimulate Na+, K+-ATPase from various tissue preparations. However, it is unclear whether or not this stimulation occurs in myocardial tissues. We have evaluated possible catecholamine stimulation of purified Na+, K+- ATPase preparations utilizing a bovine ventricular microsomal preparation. We have studied the dose response of the enzyme to ouabain and digitoxigenin in the presence and absence of propranolol and norepinephrine. Our results indicate that propranolol increases the sensitivity of Na+, K+-ATPase to inhibition by digitalis, and that stimulation of Na+, K+-ATPase in bovine myocardium is not mediated via an adrenergic mechanism. In addition, our results indicate that in myocardial tissue, both stereoisomers of propranolol produce a direct nonspecific membrane effect which can modify Na+, K+-ATPase activity.

Animals↗
PubMedDate not supplied

An overview of leukocyte depletion in blood transfusion.

The importance of removing leukocytes from the blood before transfusion has been recognized, but the complete value has not yet been totally ascertained. In this article, past accomplishments are reviewed and future uses are outlined.

Blood Transfusion↗
PubMedDate not supplied

Blood transfusion reactions involving an immune response.

The majority of reactions that occur during blood transfusion are stimulated when the recipient receives antigen from donor blood to which he has developed antibody. The reaction may be immediate or insidious in its onset. Side effects range from mild discomfort to death. The transfusionist needs to be able to distinguish symptoms of a reaction and be prepared to treat them immediately.

Blood Group Incompatibility↗
PubMedDate not supplied

Nonimmune transfusion reactions: when type-and-cross match aren't enough.

The administration of any blood component carries with it the potential of an adverse reaction. Many times, these reactions can be blamed on the biological aspect of the blood. Because the antigen profile of blood varies among individuals, incompatabilities which are known as immune responses, may occur during transfusion. However, even when donor blood is a perfect antegenic match, it is possible for transfusion reactions to occur. These reactions are considered nonimmune, and may be linked to the collection, preparation or administration of the blood. Certain predisposing factors, such as liver or renal failure, patient size, or pre-existing disease may affect a patient's tolerance to donor blood. Nonimmune transfusion reactions involve not only refrigerated blood components, but also commercially prepared products. Below, nine reactions involving a nonimmune response are discussed.

Blood Grouping and Crossmatching↗