Circadian oscillators, cell cycles, and singularities: light perturbations of the free-running rhythm of cell division in Euglena.

The free-running circadian rhythm of cell division in the algal flagellate, Euglena gracilis (Z) was perturbed by 3-h light signals of varying intensities imposed at different circadian times (CT). Light pulses within the range of 700 to 7,500 lux were found to yield the same 'strong' (Type 0) phase response curve (PRC) comprising both advance and delay phase shifts as great as 15 h. Dark signals generated a PRC of reduced amplitude with very little, if any, phase advance being observed.

A comparison of Blalock-Taussig, Waterston, and polytetrafluoroethylene shunts in children less than two weeks of age.

Results obtained with Blalock-Taussig, Waterston, and polytetrafluoroethylene (PTFE) shunts were compared in 67 cyanotic infants less than 2 weeks of age. A different shunt was preferably used at each of three institutions. The incidences of early shunt failure (3 out of 21, 14%), mortality after revision of early shunt failure (0 out of 3), and overall hospital mortality (1 out of 21, 5%) were all lowest for the PTFE shunt.

Management of infected thoracic aortic prosthetic grafts.

Between 1975 and 1981, late infection of the prosthesis developed in 4 out of 207 patients (1.9%) who had prosthetic grafts placed in the chest or mediastinum. Organisms were Staphylococcus epidermidis (2 patients), Enterococcus, and Aspergillus.

Cell division cycles and circadian oscillators in Euglena.

The algal flagellate Euglena grown photoautotrophically in L:D 3:3 displays a circadian rhythm of cell division. Oscillatory models for cell cycle (CDC) control (particularly those of the limit cycle variety) include the property of phase perturbation, or resetting. This prediction has been tested in synchronous cultures in which the free-running rhythm has been scanned by 3-hr light signals.

Chronobiology at the cellular and molecular levels: models and mechanisms for circadian timekeeping.

This review considers cellular chronobiology and examines, at least in a superficial way, several classes of models and mechanisms that have been proposed for circadian rhythmicity and some of the experimental approaches that have appeared to be most productive. After a brief discussion of temporal organization and the metabolic, epigenetic, and circadian time domains, the general properties of circadian rhythms are enumerated. A survey of independent oscillations in isolated organs, tissues, and cells is followed by a review of selected circadian rhythms in eukaryotic microorganisms, with particular emphasis placed on the rhythm of cell division in the algal flagellate Euglena as a model system illustrating temporal differentiation.

Aortopulmonary window and aortic isthmic hypoplasia. Operative management in newborn infants.

Aortopulmonary window with aortic isthmic hypoplasia is an unusual combination of congenital heart lesions that usually causes severe heart failure, poor systemic perfusion, and death shortly after birth. In 21 previously reported cases, survival beyond infancy was uncommon, yet only one neonate survived operation. This report describes three cases of aortopulmonary window and aortic isthmic hypoplasia and a two-stage operative approach that proved successful in both infants in which it was tried.

Extracorporeal left ventricular assistance with prostacyclin and heparinized centrifugal pump.

A temporary left ventricular assist system utilizing an improved left atrial catheter and centrifugal pump was developed and tried in 22 anesthetized sheep to test the hypothesis that prostacyclin (PGI2) and ionically bound heparin-coated surfaces could prevent thrombosis in this perfusion system without inhibiting soluble, circulating coagulation factors. Sheep were perfused at 53.6 ml/kg/min (standard error, 1.

Surgical treatment of purulent pericarditis in children.

Since 1971 we have seen 15 children with the diagnosis of purulent pericarditis. The causative organism was Hemophilus influenzae in seven, Staphylococcus aureus in three, and five were due to other organisms. In one child the diagnosis was unsuspected until autopsy.

A computer assisted quality assurance model.

This article describes a modular quality assurance program that was designed for computer automation. The author explains how the quality assurance model not only meets this need but also satisfies other critical objectives, including integration with the hospital's multidisciplinary quality assurance program and minimal redundancy in developing standards and measurement criteria. Readers will benefit from ideas for refining or developing effective quality assurance programs that can also use computer technology to increase productivity.

Inhibition of human platelet function by verapamil.

We evaluated the ability of the calcium antagonist, verapamil, to alter human platelet function. With the concentrations tested (20 ng to 0.1 mg/ml of whole blood), verapamil inhibited epinephrine-induced aggregation and release of 14C-serotonin; produced a dose-dependent inhibition of 14C-serotonin uptake and prevented aggregation dependent release of thromboxane B2.

Prognosis of pulmonary scar carcinoma.

Eighty-one patients with resectable primary peripheral lung carcinomas were studied to determine the effect of associated scarring on prognosis. Twelve tumors (15%) originated from bronchi. 24 (30%) were associated with scars, and 45 (55%) were not associated with either bronchus or scar (non-scar).

Cell division cycles and circadian clocks : phase-response curves for light perturbations in synchronous cultures of euglena.

The cell division rhythm in Euglena gracilis Klebs (Z strain) freeruns with a circadian period (30.2 +/- 1.8 hours for 156 monitored oscillations) in aerated, magnetically stirred, 8-liter, axenic batch cultures grown photoautotrophically at 25 degrees C in LD: 3,3, (7,500 lux, cool-white fluorescent) 6-hour light cycles from the moment of inoculation.

Thromboembolic complications of current cardiac valvular prostheses.

Thromboembolic complications associated with twelve different models of currently available aortic and mitral valve prostheses are reviewed. There is a need to standardize definitions of thrombotic phenomena and to report these events for valve model and anatomic location actuarially and in terms of incidence per 100 patient-years of follow-up. The incidence of thromboemboli is less than 2 per 100 patient-years for aortic biological valves without coumarin anticoagulation and for the best mechanical valves with coumarin.

Release of lysosomal hydrolases during simulated extracorporeal circulation.

Contact with surfaces results in activation of formed blood elements. This study demonstrates that during extracorporeal circulation, release of lysosomal enzymes occurs concomitantly with platelet granule secretion. Fresh, heparinized human blood was recirculated for 2 hours at 1,000 ml/min at 37 degrees C in silicone rubber circuits containing a membrane oxygenator (0.

Platelet function during cardiac operation: comparison of membrane and bubble oxygenators.

The effects of cardiopulmonary bypass with bubble and membrane oxygenator systems on platelet function were studied in 26 patients who had elective coronary arterial bypass grafts. Fourteen patients were perfused with spiral coil membrane oxygenator systems, 12 with bubble oxygenator systems. During and after bypass, platelet counts decreased in both groups; however, when corrected for dilution, platelet counts did not change significantly in patients perfused with membrane oxygenators and increased slightly but significantly in those perfused with membrane oxygenators and increased slightly but significantly in those perfused with bubble oxygenator systems.