Biomedical subjects
Publications and source records attributed to M W Cooper.
We report a case of sensing malfunction in which supraventricular tachycardia was repeatedly induced, then terminated appropriately, by an antitachycardia pacemaker.
The utility of the antiarrhythmic drug procainamide (PA) is limited by the required dosage schedule (every three to four hours). A commercially available, slow release procainamide (P-SR) is recommended to be given every six hours. We compared procainamide capsules (P-Caps) given every four hours with P-SR given every six hours in a crossover study of 12 patients. Doses of P-Caps were chosen to produce a therapeutic result and serum drug concentrations within the therapeutic range. Doses of P-SR were adjusted until serum PA concentrations were similar to those when P-Caps were used. The dosage for P-Caps was 58 mg/kg/day +/- 24.6; P-SR dosage was 53 mg/kg/day +/- 15.18 (mean +/- SD) (P not statistically significant). The PA peak to trough variation for P-Caps was 2.2 micrograms/ml +/- 2.3 and for P-SR 1.5 micrograms/ml +/- 1.4 (P not significant). We conclude that P-SR given every six hours in the same daily dose as PA capsules given every four hours will provide similar therapeutic concentrations with no greater peak to trough variation.
A comparative study was performed to determine the accuracy of a programmable calculator with supplemental digitizer in echocardiographic analysis. Twenty separate measurements were collected per heart beat from five different dogs, taking five heart beats from each dog. The measurements were made by an echocardiographic technician (ET), echocomputer (EC), and by a programmable calculator (HP). In a triple comparison (ET-HP, ET-EC, HP-EC) there were no significant differences in the values obtained, suggesting that the programmable calculator can provide a highly accurate and rapid means of processing echocardiographic measurements, thereby providing the advantages of the echocomputer without the cost of such a device.
A method is described for the use of echocardiography in volume determinations in the experimental animal. Suitability of the technique in both acute and chronically implanted animals was tested. Stroke volumes derived from calculations based on echo data were compared with those obtained by an electromagnetic flow probe placed around the aorta. High correlation was found in both the acute (r = 0.96, P less than 0.001) and the chronic (r = 0.89, P less than 0.001) preparations. Cardiac output computed from echocardiographic data and compared with those based on either flow probe or indicator-dilution techniques also showed a high degree of correlation in both the acute (r = 0.91 and 0.95, respectively; P less than 0.001) and chronic (r = 0.98 and 0.94, respectively, P less than 0.001) preparations. It is suggested that echocardiography, because of the potential to measure many indicators of myocardial function in addition to volume, represents a significant improvement in the techniques available for basic cardiovascular experimentation.
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Malignant mesothelioma is extensively described in the radiological literature, but the incidence and importance of rib destruction has not been emphasised. In this communication, four patients with extensive mesothelioma and contiguous rib destruction are described. They represent 12% of the collected series of 36 patients. The differential diagnosis of a pleural mass with rib destruction is discussed.
These studies were conducted to examine the basic characteristics of postextrasystolic potentiation (PESP) and the relationship of loading effects to PESP. Measurements of left ventricular (LV) and aortic pressures, the rate of pressure rise, and echocardiographically determined LV dimensions were made in anesthetized open-chest dogs. The hearts were paced, and timed extrasystoles were introduced that were followed by postextrasystoles (PES). PES's were elicited after an interval equal to either a full compensatory pause or a time when the diastolic properties of the LV could not be distinguished from control (isolength). Potentiation of contraction for the PES's introduced after an isolength pause was dependent on both the heart rate and the extrasystolic interval, whereas the PES's that occurred after a full pause showed no dependence on either of these intervals. PESP elicited during the isolength period was not dependent on either preload and afterload. It is concluded that PESP depends on the combination of heart rate and extrasystolic and postextrasystolic intervals. Further, PESP may be inaccurate in assessing contractile reserve unless the heart rate and extrasystolic interval are known and the PES is introduced after an isolength pause.
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Blood samples obtained from 97 consecutive patients admitted to the hospital for chest pain were analyzed for taurine concentrations. The mean value of the maximum taurine concentration in whole blood from AMI patients were greater than the mean value of the maximum taurine concentration in patients without AMI. There was no difference in plasma taurine levels between AMI and non-AMI patients, indicating that a cellular component(s) of whole blood was sequestering taurine. The increased blood taurine concentrations in the AMI patients evolved over the course of 70 hr and paralleled the increase in total CK levels. Blood taurine concentrations, in general, did not rise in patients who had chest pain of unknown etiology, skeletal muscle trauma, pleuritic pain, SVT/VT plus CV, acute pericarditis, acute cholecystitis, or angina pectoris. It is concluded that blood but not plasma taurine concentrations rise after acute myocardial injury and tend to be higher the more extensive the infarction. The mechanism of the blood taurine rise is unknown, but a myocardial source is probable. Also, there is evidence that the myocardium selectively leaks taurine, and not other amino acids. Monitoring blood taurine concentration in AMI may provide useful diagnostic and prognostic information.
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Embryos collected surgically from donors superovulated with PMSG and synchronized with either prostaglandin F(2)alpha or progestagen impregnated sponges were transferred non-surgically to prostaglandin or progestagen synchronized recipients. One embryo was transferred to the uterine horn ipsilateral to the corpus luteum either through a flexible catheter introduced through a steel tube and passed to the uterine tip, or through a Cassou inseminating gun passed approximately 6 cm into the horn. Of 16 recipients receiving 5 or 6 day old embryos through the catheter (1976), 6 (38%) were palpated pregnant at 42 days and 4 (25%) subsequently calved. Of 16 recipients receiving 7 or 8 day old embryos through the straw and 16 through the catheter (1977), 10 (63%) and 3 (19%), respectively, were palpated pregnant (P<0.05) and 8 (50%) and 3 (19%), respectively, had normal embryos at slaughter 4 to 29 days after palpation (P reverse similar0.10 ). Forty 7 to 9 day old embryos were transferred through the straw in 1978. Eighteen (45%) of the recipients were palpated pregnant and 16 (40%) had normal embryos at slaughter 98 to 168 days after palpation. The success of the transfers in 1978 was affected by embryo quality [good vs poor embryos; 64% vs 22% recipients pregnant (P<0.01) and 59% vs 17% embryos surviving to slaughter (P<0.05)]. Also, in 1978, pregnancy rate was affected by the time taken to transfer the embryo with the highest rate achieved with the fastest transfers (P<0.10, b = -0.47). Injection of Indomethacin near the time of transfer, synchronization between donor and recipient onset of estrus and embryo age did not affect pregnancy rates. The pregnancy rate achieved after the transfer of good quality embryos by the straw technique was equal to that expected from surgical techniques.
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Relationship between postextrasystolic potentiation and slow-phase force-frequency response in guinea-pig ventricular myocardium. Acta physiol. pol. 1985, 36 (2): 175-184. We investigated relationship between postextrasystolic potentiation (PESP) and a form of slow-phase force-frequency relation, namely the post-rest recovery of contractile force (CF). We found that although the degree of post-rest recovery of CF determines CF of the potentiated beats, PESP does not affect the time-course of post-rest recovery, even if it is sustained by means of paired stimulation. Moreover, PESP may be completely or almost completely inhibited by caffeine in 10 mmolar concentration, whereas post-rest recovery is not significantly affected by this drug. We conclude, that PESP and slow force-frequency relations are based on separate cellular mechanisms.