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Biomedical subjects

M Artman

Publications and source records attributed to M Artman.

At least 73 records · Page 4Linked to original sources
PubMed1984

Comparative effects of verapamil, nifedipine, and diltiazem on contractile function in the isolated immature and adult rabbit heart.

The effects of postnatal development on the systolic and diastolic responses to pharmacologic blockade of the slow inward calcium current were investigated in blood-perfused hearts isolated from immature (14-21-day-old) and adult rabbits. Isovolumic left ventricular developed pressure, resting pressure, and maximal rate of pressure development (+dP/dt) at cumulative doses of either verapamil, nifedipine, or diltiazem were determined by means of an intracavitary balloon. Myocardial contractile function in the immature heart was more sensitive to pharmacologic blockade of the slow inward calcium current than is the adult heart. Doses of verapamil, or nifedipine, that comparably reduced pretreatment developed pressure and +dP/dt were approximately 10-fold less in immature as compared to the adult heart. The dose of diltiazem which reduced developed pressure and dP/dt by 50% was 3-fold less in immature as compared to the adult heart. Verapamil and nifedipine decreased resting pressure in the adult but not in the immature heart. Conversely, diltiazem decreased resting pressure in the immature while not affecting resting pressure in adult hearts. Thus, postnatal cardiac development affects both the systolic and diastolic responses to calcium channel blockade. In addition, diltiazem appears to be qualitatively and quantitatively different from verapamil and nifedipine with respect to the age-related cardiac effects of calcium channel blockade.

Aging↗
PubMed1983

Radionuclide stroke count ratios for assessment of right and left ventricular volume overload in children.

The ratio of left ventricular to right ventricular stroke counts measured by radionuclide angiography has been used in adults to estimate the severity of left-sided valvular regurgitation. The validation of this technique in children for assessment of right and left ventricular volume overload is reported herein. Radionuclide stroke count ratios in 60 children aged 0.5 to 19 years (mean 11) were determined. Based on their diagnoses, the patients were divided into 3 groups: (1) normal--40 patients with no shunts or valvular regurgitation, (2) left ventricular volume overload--13 patients with mitral or aortic regurgitation, or both, and (3) right ventricular volume overload--7 patients, 2 with severe tricuspid regurgitation, 3 with atrial septal defects, and 2 with total anomalous pulmonary venous drainage. The radionuclide stroke count ratio clearly differentiated these groups (p less than 0.05): normal patients had a stroke count ratio of 1.04 +/- 0.17 (mean +/- 1 standard deviation), the left ventricular volume overload group had a stroke count ratio of 2.43 +/- 0.86, and the right ventricular volume overload group had a stroke count ratio of 0.44 +/- 0.17. In 22 of our 60 patients, radionuclide stroke count ratios were compared with cineangiographic stroke volume ratios, resulting in a correlation coefficient of 0.88. It is concluded that radionuclide ventriculography is an excellent tool for qualitative and quantitative assessment of valvular regurgitation in children.

Adolescent↗
PubMed1983

Clonidine poisoning. A complex problem.

Clonidine hydrochloride poisoning in children has become more frequent with increasing availability of this drug. We report four cases of accidental clonidine poisoning that demonstrate the various signs and symptoms of clonidine poisoning. The most frequent and significant toxic effects are depression of consciousness, bradycardia, hypotension, and respiratory depression. Ventilatory support must be available if apnea occurs. Bradycardia can be treated with atropine sulfate, epinephrine chloride, dopamine hydrochloride, or tolazoline hydrochloride. Hypotension is treated with intravenous fluids and dopamine, reserving tolazoline for refractory cases. Hypothermia is common but is of minor clinical significance. Paradoxical hypertension should be treated with tolazoline. Clonidine may not be detected in body fluids by routine toxicology-screening procedures, so poisoning should be suspected on clinical grounds.

Apnea↗
PubMed1983

Emergency palliation of critical valvular aortic stenosis. A new application of prostaglandin E1.

Prostaglandin E1 (PGE1) was administered by continuous infusion to a critically III 3-day-old infant with severe stenosis of the aortic valve. A beneficial response was evidenced by increases in systemic BP, pulses, perfusion, urinary output, and arterial pH. The infusion of PGE1 improved and stabilized the infant's condition so that cardiac catheterization and surgery could be performed. Successful aortic valvulotomy was performed with continued PGE1 infusion. To out knowledge, this report is the first to describe a patient in whom PGE1 was used successfully for palliation of critical aortic valvular stenosis.

Aortic Valve Stenosis↗
PubMed1983

Growth of Haemophilus influenzae in simulated blood cultures supplemented with hemin and NAD.

The mean generation time of Haemophilus influenzae in simulated blood cultures is 103 to 107 min. With 0.56 to 0.58 doublings per h, even large inocula of 256 cells per ml reach only 2 X 10(6) cells per ml and produce no visible evidence of growth after 24 h of incubation. Hemin and NAD added to simulated blood cultures triple the rate of growth of H. influenzae, so that even small inocula produce visible turbidity after overnight incubation. With a mean generation time of 36 min, a single cell of H. influenzae in simulated blood culture supplemented with hemin and NAD undergoes 30 doublings in 18 h, producing 2(30) (1.07 X 10(9] cells and visible turbidity.

Blood↗
PubMed1982

Nicotinamide adenine dinucleotide and nicotinamide adenine dinucleotide phosphate splitting enzyme(s) of sheep and rabbit erythrocytes: their effect on the growth of Haemophilus.

Fragility of rabbit erythrocytes in agar plates results in gradual release of their NAD and NADP contents into the medium. Due to high NADase and negligible NADPase activity of rabbit red blood cell stroma at neutral pH, the NAD released into the medium is hydrolyzed and NADP remains intact. Thus, rabbit erythrocytes and their lysates support the growth of NAD(P)-requiring Haemophilus by serving as a source of NADP. Stability of sheep erythrocytes in agar plates results in retention of their NAD and NADP contents and consequently in inhibition of growth of NAD(P)-requiring Haemophilus. The highly active NAD- and NADP-splitting enzyme(s) of sheep red blood cell stroma prevent(s) the growth of Haemophilus on sheep blood lysates through inactivation of both NAD and NADP which are released into the medium.

Animals↗
PubMed1982

Propranolol in children: safety-toxicity.

Four hours after acute ingestion of 400 to 1,200 mg of propranolol by a healthy, 3-year-old boy, his plasma concentration of propranolol was 2,289 ng/ml. The only pharmacologic effect observed was a diminished heart rate response to crying and activity. In a second case, a 4-year-old boy on chronic propranolol therapy for renovascular hypertension had a hypoglycemic seizure when solid food was refused for three days because of an oral wound. The hypoglycemia was easily managed with intravenous glucose, and there were no sequelae. The first case alludes to the safety of propranolol in a healthy child even with very high plasma concentrations. The second case suggests the necessity of anticipating and avoiding hypoglycemia that can develop in children on chronic propranolol therapy when caloric intake is impaired.

Child, Preschool↗
PubMed1981

Studies on the sidedness of the human red blood cell membrane: preparation of stable azo-erythrocytes.

Para-diazobenzenesulfonic acid (DBSA), a non-penetrating compound, which reacts with proteins of the external surface of intact cells, was used for the preparation of AZO-erythrocytes. When coupling of p-diazobenzenesulfonic acid to human red blood cells was carried out in phosphate-buffered saline (PBS), the cells lysed within one hour, before the completion of the reaction. Elimination of sodium chloride from the reaction mixture allowed the completion of coupling by prolonging the survival of red blood cells in he diazonium salt from one hour to three hours. The survival of human erythrocytes could be further prolonged to seven hours by carrying out coupling in the presence of cyclic 3',5'-guanosine monophosphate (cGMP). Azo-erythrocytes prepared in the absence of cyclic GMP and washed free of the diazonium salt lysed in phosphate-buffered saline, but remained stable for hours in isosmotic phosphate buffers devoid of sodium chloride ions. Under identical conditions, azo-erythrocytes prepared in the presence of cyclic GMP remained stable for two days and were suited for studies on the functional and structural aspects of red blood cell membrane.

Acetylcholinesterase↗