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Biomedical subjects

M O'Grady

Publications and source records attributed to M O'Grady.

15 recordsLinked to original sources
PubMed1992

Rapid, simple and sensitive microassay for skeletal and cardiac muscle myoglobin and hemoglobin: use in various animals indicates functional role of myohemoproteins.

A novel, simple, rapid, sensitive and reproducible microassay is described for determination of myoglobin and hemoglobin content of myocardial and skeletal muscle biopsy specimens from various mammals, birds and fish. As little as 50 mg of tissue is needed and myoglobin concentrations lower than 1 mg% can be detected. Myoglobin and hemoglobin are separated at alkaline pH by ammonium sulfate extraction followed by ultrafiltration. Heme content is determined by absorption of the Soret band when the hemoprotein extract is visibly colored or more sensitively by its peroxidase activity when the extract has low color. The heme reacts with tertiary-butyl hydroperoxide and orthotolidine to generate a blue color. Hemoglobin content is correlated with myoglobin content and is related to aerobic capacity and blood flow to the tissue. Myoglobin content varied over 5 orders of magnitude up to 7 per cent of the weight of tissue, whereas hemoglobin content varied over 2 orders of magnitude up to 6 per cent of tissue weight. Myoglobin content is increased in species with high basal metabolic rate, high physical activity, prolonged diving capacity, fatigue resistance, and red muscle, whereas it is decreased in white muscle, iron-deficient animals, animals with sedentary lifestyles, and in animals and tissues with small fiber diameters such as avian or fish hearts.

Animals↗
PubMed1992

Myocardial myoglobin deficiency in various animal models of congestive heart failure.

Myoglobin is known to protect the mechanical function of the heart from hypoxia by acting as a sarcoplasmic oxygen reservoir and shuttle. We postulated a role for myoglobin in the pathogenesis of congestive heart failure. Several models of congestive heart failure were employed to test the hypothesis, including spontaneous inherited dilated cardiomyopathy in Doberman Pinschers, and heart failure produced by rapid ventricular pacing in dogs, volume overload in chickens and furazolidone toxicity in turkeys. Myocardial myoglobin was decreased by approximately 50% for all models (P less than 0.05). In Doberman Pinschers dogs which are predisposed to the development of dilated cardiomyopathy and have mild subclinical depression of cardiac performance, myocardial myoglobin (1.05 +/- 0.22 mg/g) is approximately 50% decreased compared to healthy mongrel dogs (2.15 +/- 0.52 mg/g), approximately twice as much as dobermans with heart failure (0.47 +/- 0.25 mg/g) but similar to the concentration found in dogs paced to heart failure (1.09 +/- 0.34 mg/g). Myocardium from poultry had remarkably decreased myoglobin compared to mammals (34 +/- 4 micrograms/g) with heart failure produced either by furazolidone or salt toxicity causing a further 50% reduction. In the canine models of heart failure, myocardial myoglobin concentration was demonstrated to be correlated with biochemical and physiological indicators of myocardial performance, namely, mitochondrial and sarcoplasmic reticular ATPase activities, and cardiac output, systemic vascular resistance, pulmonary capillary wedge pressure and mean arterial pressure, respectively. Our data implicates a role for myoglobin deficiency in the pathogenesis of congestive heart failure and in the predisposition of doberman pinschers to dilated cardiomyopathy.

Animals↗
PubMed1992

Respiratory chain defect of myocardial mitochondria in idiopathic dilated cardiomyopathy of Doberman pinscher dogs.

Idiopathic dilated cardiomyopathy (IDCM) is a primary myocardial disease of unknown cause. We tested the hypothesis that IDCM was associated with a myocardial metabolic defect by determining a comprehensive biochemical profile of metabolite concentrations and enzyme activities for the major metabolic pathways of the myocardium. We used the Doberman pinscher breed as a naturally occurring canine model of IDCM and compared its myocardial profile with that of healthy adult mongrels. Compared with controls, myocardium in IDCM had markedly reduced mitochondrial electron transport activity and myoglobin concentration, in association with acidosis and energy depletion following anoxic challenge: 60% decreased NADH dehydrogenase and 50% decreased ATP synthetase activities; 90% decreased myoglobin concentration; and 30% reduced ATP and 50% increased lactate and proton concentrations. Sarcoplasmic reticulum Ca(2+)-transport ATPase was decreased by 42%. There was a 15% compensatory increase in fatty acid oxidation and Krebs cycle activity. Other biochemical changes were mild by comparison with the mitochondrial defects. We conclude that IDCM is associated with a marked impairment of mitochondrial production of ATP, arising from decreased activity of the mitochondrial electron transport system, including myoglobin. These changes may be secondary to an underlying genetic defect or may indicate a deficiency of the mitochondrial respiratory chain that predisposes this breed to heart failure.

ATP Synthetase Complexes↗
PubMed1992

Normal pressure hydrocephalus. A potentially reversible form of dementia.

1. Normal pressure hydrocephalus (NPH) is a rare but potentially treatable form of dementia. Shunting will improve functioning in 40% to 50% of patients. 2. The classic symptoms of NPH are dementia characterized by mild memory impairment and apathy, ataxic gait, and urinary hesitancy or incontinence. 3. The patient with NPH may present with psychiatric symptoms of depression, paranoia, visual hallucinations, irrational hostility, and aggression or mania. 4. Patients with NPH are indifferent about activities of daily living and personal safety and require close supervision.

Aged↗
PubMed1990

[The role of drugs, irradiation, autoimmune diseases and age in the development of xerostomia in the Irish Republic].

The effects are described of xerostomia on the oral mucosa and dental structures. The various conditions which give rise to extreme dryness are listed; a rough estimate is made on the prevalence of these conditions. The contribution of drug induced xerostomia, of post irradiation mouth dryness and of autoimmune associated salivary disorders are dealt with. Reference is made to studies of xerostomia in various subpopulations. The prevalence of diseases known to be associated with mucosal dryness, and the yearly patterns of drug prescription in Ireland are used to justify an estimate of 2.1% to 3.3% of the population to be the incidence of xerostomia in the Republic of Ireland.

Age Factors↗
PubMed1987

Effects of saffan on cardiopulmonary function in healthy cats.

The effects of saffan on cardiopulmonary function were evaluated in eight healthy adult cats. Measured values were cardiac output by thermodilution, heart rate by electrocardiogram, arterial blood gases, respiratory rate and systolic, diastolic and mean arterial blood pressures by arterial catheterization. Calculated values included cardiac index, stroke volume and systemic vascular resistance. Statistical analysis employed paired t-tests comparing pre saffan anesthetic induction and post saffan anesthetic parameters over a 120 minute time sequence. Thirty min after saffan induction, significant depression in cardiac output was evident while stroke volume was significantly depressed at 45 and 60 min, systolic blood pressure at 15 min and respiratory rate at 5, 10 and 15 min. No significant changes occurred in cardiac index, heart rate, arterial blood gases, diastolic and mean arterial blood pressure or systemic vascular resistance. It was concluded that saffan causes significant depression of cardiopulmonary function in normal adult cats.

Alfaxalone Alfadolone Mixture↗
PubMed1983

Erythrocyte volume distribution analysis and hematologic changes in dogs with iron deficiency anemia.

Hematologic features were characterized in 12 dogs with iron deficiency anemia attributable to chronic external blood loss. Consistent abnormalities in hemograms included moderate to marked reticulocytosis, decreased mean corpuscular volume, and decreased mean corpuscular hemoglobin concentration. Hypoproteinemia occurred in only four of 12 dogs. Consistent blood film findings included hypochromic cells, leptocytosis, and erythrocyte fragmentation. These dogs had significantly decreased serum iron values (p less than 0.001) and percent transferrin saturation values (p less than 0.001) compared with 33 clinically healthy adult dogs. The total iron binding capacity values of these dogs were not significantly different (p greater than 0.5) than those of the healthy dogs. Using erythrocyte volume distribution curves, the percentages of microcytic cells (less than or equal to 45 fl) were determined to range from 20% to 82%. Sequential changes in erythrocyte subpopulations were evaluated in four dogs which received iron therapy. The hematologic response consisted of fairly rapid restoration of packed cell volume by production of normocytes followed by a more gradual replacement of residual microcytes by new normocytes.

Anemia, Hypochromic↗