Ventilatory control during exercise in calves with artificial hearts

To determine the role of cardiac reflexes in mediating exercise hyperpnea, we investigated ventilatory responses to treadmill exercise in seven calves with artificial hearts and seven controls. In both groups, the ventilatory responses were adequate for the metabolic demands of the exercise; this resulted in regulation of arterial PCO2 and pH despite the absence of cardiac output increase in the implanted group. In this group, there was a small but significant reduction of arterial PO2 by 4 +/- 3 Torr and a rise of blood lactate by 1.1 +/- 1 mmol/l. When cardiac output was experimentally increased in the implanted calves to a level commensurate with that spontaneously occurring in the control calves, ventilation was not affected. However, experimental reductions of cardiac output led to an immediate augmentation of exercise hyperpnea by 4.56 +/- 4.3 l/min and a further significant lactate increase of 1.2 +/- 1.22 mmol/l that was associated with a significant decrease in the exercise O2 consumption (0.32 +/- 0.13 l/min). These observations indicate that neither cardiac nor hemodynamic effects of increased cardiac output constitute an obligatory cause of exercise hyperpnea in the calf.     

Measurement and analysis of gas exchange during exercise using a programmable calculator

Although exercise testing is useful in the diagnosis and management of cardiovascular and pulmonary diseases, a rapid comprehensive method for measurement of ventilation and gas exchange has been limited to expensive complex computer-based systems. We devised a relatively inexpensive, technically simple, and clinically oriented exercise system built around a desktop calculator. This system automatically collects and analyzes data on a breath-by-breath basis. Our calculator system overcomes the potential inaccuracies of gas exchange measurement due to water vapor dilution and mismatching of expired flow and gas concentrations. We found no difference between the calculator-derived minute ventilation, CO2 production, O2 consumption, and respiratory exchange ratio and the values determined from simultaneous mixed expired gas collections in 30 constant-work-rate exercise studies. Both tabular and graphic displays of minute ventilation, CO2 production, O2 consumption, respiratory exchange ratio, heart rate, end-tidal O2 tension, end-tidal CO2 tension, and arterial blood gas value are included for aid in the interpretation of clinical exercise tests.     

Alteration by hyperoxia of ventilatory dynamics during sinusoidal work

The effects of hyperoxia on ventilatory and gas exchange dynamics were studied utilizing sinusoidal work rate forcings. Five subjects exercised on 14 occasions on a cycle ergometer for 30 min with a sinusoidally varying work load. Tests were performed at seven frequencies of work load during air or 100% O2 inspiration. From the breath-by-breath responses to these tests, dynamic characteristics were analyzed by extracting the mean level, amplitude of oscillation, and phase lag for each six variables with digital computer techniques. Calculation of the time constant (tau) of the ventilatory responses demonstrated that ventilatory kinetics were slower during hyperoxia than during normoxia (P less than 0.025; avg 1.56 and 1.13 min, respectively). Further, for identical work rate fluctuations, end-tidal CO2 tension fluctuations were increased by hyperpoxia. Ventilation during hyperoxia is slower to respond to variations in the level of metabolically produced CO2, presumably because hyperoxia attenuates carotid body output; the arterial CO2 tension is consequently less tightly regulated.     

Alterations of the electrophoretic mobility distribution of rat mast cells after immunologic activation.

Changes in the electrophoretic mobility distributions of rat serosal mast cells after immunologic activation have been measured using the laser Doppler technique of electrophoretic light scattering. Rat serosal mast cells of 98% purity isolated by isopycnic and velocity gradient sedimentation had a highly negative electrophoretic mobility which was unaffected by incubation with normal rabbit serum or, at 4 degrees C or in the absence of Ca+2, with rabbit anti-rat E(ab')2 antiserum. Immunologic activation of the cells with this antiserum in the presence of Ca+2 at 37 degrees C resulted in a dose- and time-dependent increase in the electrophoretic mobility. Thus at a 1:25 dilution of anti-F(ab')2 the mean and mode electrophoretic mobilities of the mast cell population increased 25 and 21%, respectively. The width of the electrophoretic mobility distribution also increased with activation, indicating a heterogeneous response of the mast cells in the population. The increase in electrophoretic mobility after immunologic activation is not diminished by treatment of the cells with 1 M NaCl to solubilize adsorbed mast cell granule or heparin.     

Treatment of psoriasis with orally administered 8-methoxypsoralen and long-wavelength ultraviolet radiation.

Between May 1976 and September 1977, 51 patients with severe psoriasis were treated with orally administered 8-methoxypsoralen followed by exposure to high-intensity long-wavelength ultraviolet radiation. Clearing of psoriasis occurred in 40 patients (78%) and marked improvement in 5 (10%). Of the remaining patients three (6%), who had generalized erythroderma, failed to respond to this therapy. The mean number of treatments required for clearing was 37.5. No serious side effects were noted clinically, by ophthalmologic examination or by laboratory testing. This therapy has some advantages over conventional types of treatment now used for severe psoriasis, but also has limitations. It appears to be an effective method of treatment for ambulatory patients. Further long-term follow-up studies are required to evaluate its side effects.     

The isolation, identification and characterization of sulfated glycosaminoglycans synthesized in vitro by human eosinophils

Human eosinophils were purified to greater than 92% using 16-30% metrizamide gradients, and these cells cultured for up to 72 h in vitro to label sulfated glycosaminoglycans. Over 90% of the sulfated glycosaminoglycan-containing material was extracted in 4 M guanidine HCl and had a hydrodynamic size similar to a glycosaminoglycan marker with an approximate average molecular weight of 60,000. Treatment of this salt-extracted 35S-labeled glycosaminoglycan-containing material with 0.5 M NaOH resulted in a change in mass to approx. 20,000 daltons, suggesting that the larger molecules were proteoglycans with side chains with an approximate molecular weight of 20,000. These salt extracted presumptive 35S-labeled proteoglycans were protease insensitive and behaved in a highly charged fashion on DEAE-cellulose. The composition of 35S-labeled glycosaminoglycans from human eosinophils as identified using selected polysaccharides was 70-81% chondroitin 4-sulfate, 9-12% chondroitin 6-sulfate, and 5-12% dermatan sulfate. The predominance of chondroitin 4-sulfate in human eosinophils is similar to the predominance of chondroitin 4-sulfate in human neutrophils and human platelets.     

The role of the maturation-promoting factor in controlling protein synthesis in Xenopus oocytes

Oocyte cytosol, containing maturation-promoting factor activity, induces a twofold increase in the rate of protein synthesis as well as inducing germinal vesicle breakdown (GVBD) when microinjected into Xenopus oocytes. In the current study, it is shown that the cytosol activity responsible for inducing the increase in protein synthesis can be separated from the activity that induces GVBD in recipient oocytes.     

Calmodulin triggers the resumption of meiosis in amphibian oocytes

The calcium-binding protein, calmodulin, has been purified from Xenopus laevis oocytes. This 18,500-dalton protein, pl 4.3, has two high-affinity calcium-binding sites per mole protein having a dissociation constant of 2.8 x 10(-6) M. Full-grown Xenopus oocytes, arrested in late G2 of the meiotic cell cycle, resumed meiosis when microinjected with 60-80 ng (3-4 pmol) of calmodulin in the form of a calcium-calmodulin complex. The timing of the meiotic events in these recipient oocytes was the same as that normally induced by progesterone. Xenopus ovarian calmodulin stimulated bovine brain phosphodiesterase (PDE) 3- to 10-fold in a calcium-dependent manner, but it had no apparent effect on ovarian PDE activity. A calcium-calmodulin-dependent protein kinase has been isolated from Xenopus oocytes using a calmodulin-Sepharose 4B affinity column. The possible role for this kinase in regulating the G2-M transition in oocytes has been discussed.