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Biomedical subjects

M M Cooper

Publications and source records attributed to M M Cooper.

30 records · Page 2Linked to original sources
PubMed1986

Rapid changes in central beta-adrenergic receptors after chronic intravenous infusion of antidepressants.

The effects of intravenous infusion of desipramine (1, 3, 10, and 60 mg/kg/24 hr), amitriptyline, zimelidine, iprindole (3, 10, 30, 60, and 100 mg/kg/24 hr each), imipramine (10, 30, and 100 mg/kg/24 hr), or U-48,753E (1, 3, 10, and 30 mg/kg/24 hr) on the density of central beta-adrenergic receptors were investigated in Sprague-Dawley rats. A comparative study with oral desipramine (3 mg/kg/24 hr) for 74 hrs was also carried out. Desipramine, amitriptyline, zimelidine, iprindole, imipramine, and U-48,753E reduced the density of beta-adrenergic receptors in the cerebral cortex, and the effect seems to be dose-dependent. In the oral study, desipramine failed to down-regulate beta-adrenergic receptors. These results indicate that down-regulation of beta-adrenergic receptors can be rapidly achieved by intravenous infusion of drugs.

Administration, Oral↗
PubMed1985

Acute pancreatitis: prognostic value of CT.

In 83 patients with acute pancreatitis, the initial computed tomographic (CT) examinations were classified by degree of disease severity (grades A-E) and were correlated with the clinical follow-up, objective prognostic signs, and complications and death. The length of hospitalization correlated well with the severity of the initial CT findings. Abscesses occurred in 21.6% of the entire group, compared with 60.0% of grade E patients. Pleural effusions were also more common in grade E patients. Grades A and B patients did not have abscesses, and none died, regardless of the number of prognostic signs. Abscesses were seen in 80.0% of patients with six to eight prognostic signs, compared with 12.5% of those with zero to two. The use of prognostic signs with initial CT findings results in improved prognostic accuracy. Early CT examination of patients with acute pancreatitis is a useful prognostic indicator of morbidity and mortality.

Abscess↗
PubMed1984

Prediction of abuse liability of drugs using IV self-administration by rats.

A total 31 psychoactive drugs were offered to groups of naive rats for IV self-administration and an injection rate greater than that for rats offered only saline indicated reinforcement. Two protocols were used: in the first, rats were offered drug at a selected dose for 5 days, then the dose was reduced by 1 log unit (to 0.1 the original dose) for an additional 4 days; in the second, rats were offered saline for 3 days as a "prescreen' to eliminate rats with high or low operant-injection rates. Drug was offered to acceptable rats for 5 days, then the dose was reduced 0.5 log unit (to 0.32 the original dose) for 5 more days. A scoring system, based upon the injection rates during the last 3 days of each period, describes the reinforcing action. Scores were dose-related. Tests on both protocols gave similar results. Data from monkey studies have been reported for 27 of the drugs tested. Of these drugs, 18 were reinforcers and six were nonreinforcers in both species, nalorphine and ethylketazocine were reinforcers only in rats, and ethanol was a reinforcer only in monkeys.

Animals↗
PubMed1984

Prevention of ischemic spinal cord injury following aortic cross-clamping: use of corticosteroids.

Prior to proximal aortic cross-clamping, baseline measurements of spinal cord blood flow and function were done. Blood flow was evaluated with radioactive microspheres and function determined by assessment of somatosensory evoked potential (SEP). Group 1 (N = 6) animals had aortic cross-clamping for 5 minutes after ischemic spinal cord dysfunction (SEP loss) was documented. Group 2 (N = 9) underwent aortic cross-clamping for 10 minutes after loss of SEP. Group 3 (N = 6) also underwent 10 minutes of cross-clamping after initial SEP loss, but were treated intravenously with methylprednisolone (30 mg per kilogram of body weight) 10 minutes prior to cross-clamping and again 4 hours postoperatively. After release of the cross-clamp, the animals were allowed to recover and serial evaluations of spinal cord blood flow and neurological status were carried out for seven days. Group 1 animals recovered uneventfully without evidence of neurological injury. Group 2 animals sustained a 67% incidence of permanent spastic paraplegia (p = 0.02 versus Group 1). In contrast, methylprednisolone-treated animals sustained no clinically detectable neurological injury (p = 0.02 versus Group 2). Measurements of spinal cord blood flow at the time of SEP loss revealed similar degrees of spinal cord ischemia in all groups. No significant differences were observed in the duration of aortic cross-clamping prior to SEP loss among the three groups. The data indicate that short periods of cross-clamping (5 minutes) following SEP loss are well tolerated, whereas longer periods (10 minutes) are associated with a high incidence of paraplegia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Cortex Hormones↗
PubMed1983

Tonsillar calculi. Report of a case and review of the literature.

A large tonsillar calculus in a 77-year-old demented woman with a history of chronic oral infections and multiple episodes of pneumonia is reported. Earlier literature describes these calcium-laden tonsilloliths as occurring in adolescence following chronic tonsillitis. Improvement in health care of the young and antibiosis militate against tonsilloliths as a serious problem in the young patient. Conversely, an ever-increasing aged population, with impaired self-care abilities or diminished cerebral function, many of whom populate nursing care facilities, and increased routine oropharyngeal screening of the aged may add significantly to the number of reported cases. In view of the potential for continuous oropharyngeal disease and the possibilities of swallowing disturbances, pneumonia, or food or liquid aspiration, which may result in lethal complications the authors urge the clinician to assess masses or calcified objects viewed on physical examination or radiographs, explore their etiology, evaluate them for removal, and not dismiss them as clinically insignificant.

Aged↗
PubMed1983

Experimental and clinical assessment of the adequacy of partial bypass in maintenance of spinal cord blood flow during operations on the thoracic aorta.

We studied both experimentally and clinically the efficacy of partial bypass techniques in maintaining spinal cord blood flow and physiological function during surgical procedures on the thoracoabdominal aorta. We attempted to define the level of distal aortic pressure required to safely ensure normal neurological function in the absence of critical intercostal occlusion. Six dogs underwent left thoracotomy with baseline measurements of spinal cord blood flow and spinal cord impulse conduction (somatosensory evoked potentials). Following exclusion of the entire descending thoracic aorta from the left subclavian artery to the T-13 level, partial left atrium-femoral artery bypass was instituted, and baseline levels of proximal and distal aortic pressure were maintained during a 30-minute stabilization period. Mean distal aortic pressure then was progressively altered at 30-minute intervals to 100, 70, and 40 mm Hg. Measurements of spinal cord blood flow and somatosensory evoked potential were repeated at the end of each interval for comparison with baseline. No significant changes in spinal cord blood flow or somatosensory evoked potential were observed in any animal with a distal aortic pressure greater than or equal to 70 mm Hg. With a pressure of 40 mm Hg, normal flow and somatosensory evoked potentials were maintained in 5 of the 6 dogs. Loss of somatosensory evoked potential, with simultaneous loss of spinal cord blood flow at the T-6 level, occurred in 1 dog. Restoration of distal aortic pressure to 70 mm Hg in all animals resulted in immediate return of somatosensory evoked potential. Loss of somatosensory evoked potential routinely occurred in animals with a distal aortic pressure less than 40 mm Hg. Clinically, 9 patients have undergone operation for lesions of the thoracoabdominal aorta using shunt or bypass techniques. Normal somatosensory evoked potentials were preserved in 7 patients with maintenance of adequate distal aortic pressure (greater than or equal to 60 mm Hg) without evidence of postoperative neurological deficit. Two patients showed hypotensive somatosensory evoked potential loss (distal aortic pressure less than 40 mm Hg). Prolonged distal hypotension (85 minutes of aortic cross-clamping) in the latter resulted in paraplegia. We conclude that maintenance of a distal aortic pressure greater than 60 to 70 mm Hg will uniformly preserve spinal cord blood flow in the absence of critical intercostal exclusion. Should distal aortic pressure be inadequate, early reversible changes in the somatosensory evoked potential will alert the surgeon. Failure to institute measures to reverse these changes may result in paraplegia.

Animals↗
PubMed1979

A computer program for testing average partial association in three-way contingency tables (PARCAT).

PARCAT is a computer program which implements alternative tests for average partial association in three-way contingency tables within the framework of the product multiple hypergeometric probability model. Primary attention is directed at the relationship between two of the variables, controlling for the effects of a covariable. This approach is essentially a multivariate extension of the Cochran/Mantel-Haenszel test to sets of (s x r) tables. A set of scores such as uniform, ridits, or probits can be assigned to categories which are ordinally scaled. In particular, if ridit scores with midranks assigned for ties are utilized, this procedure is equivalent to a partial Kruskal-Wallis test when one variable is ordinally scaled, and is equivalent to a partial Spearman rank correlation test when both variables are ordinally scaled.

Age Factors↗
PubMedDate not supplied

Alterations in the cardiopulmonary effects and pharmacokinetics of a bisphosphonate drug by a cytochrome P-450 inhibitor in conscious rats.

U-91502, a bisphosphonate for arthritic inflammation treatment, was evaluated for its parental toxicity. The objective was to differentiate between the parent drug and a reactive metabolite(s) as the proximate cause of the toxic effects using two methods. The first method was to block the metabolism of U-91502 with a broad-spectrum cytochrome P-450 inhibitor, 1-aminobenzotriazole (ABT), to increase its toxicity. The second method was to scavenge any electrophilic intermediates of U-91502 with supplemental nucleophiles, L-methionine (LM) and N-acetylcysteine (NaLc) to decrease its toxicity. Two groups of rats each were given an i.v. injection of saline or ABT followed by an i.v. infusion of U-91502 at a constant dose rate. A third group was given two oral doses of LM followed by a co-infusion of U-91502 and NaLc. The breathing rate (BR) and electrocardiogram (ECG) of the rats were monitored. Blood samples were taken at specified time points for plasma drug concentration analyses (PDC) and pharmacokinetics determination. Each rat was infused until its BR was depressed by approximately 30% from the rates prior to injection of saline or ABT, or the second oral dose of LM. Thereafter, half of the rats in each group were sacrificed immediately and the remaining half at 180 min post infusion. All infused rats, except for those of the co-infusion group, and a group of untreated rats were analyzed for hepatic non-protein sulfhydryl for indication of glutathione depletion. The results indicated that ABT pretreatment expedited the elevation of PDC to a critical level that caused BR and then heart rate (HR) depression and ECG alterations. There was no unusual depletion of glutathione. The maximum concentration and the area under the curve were significantly increased while the total clearance was significantly reduced. Consequently, the postinfusion PDC remained high and the BR and HR depressions persisted. LM and NaLc did not alleviate the toxicity or alter the pharmacokinetics of U-91502. It was concluded that the toxic effects of U-91502 were due mainly to the parent drug and not the metabolites.

Acetylcysteine↗
PubMedDate not supplied

Pulmonary atresia and ventricular septal defect with coronary artery to pulmonary artery fistula: case report and review of the literature.

The pulmonary blood supply in patients with pulmonary atresia and ventricular septal defect is highly variable. Several cases have been reported in the literature in which a coronary artery to pulmonary artery fistula, alone or in combination with additional vessels, supplies the pulmonary circulation. We report a case of successful repair during early infancy, with unique hemodynamic, clinical, and anatomic features. The literature is reviewed.

Arterio-Arterial Fistula↗