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The feeding of K(15)NO3 via the xylem stream to photosynthesising leaves of Datura stramonium L. shows a massive routing of (15)N to glutamine, increasing with rise in the N-feeding level (between 0 and 400 μg N ml(-1)). At each feeding level the glutamine and glutamate pools have very similar (15)N enrichment despite disparity in pool size. Amino-compound pool-size and (15)N enrichment do not increase above the 300 μg ml(-1) feeding level which corresponds to the normal level of nitrate-N in the xylem stream of the experimental plants. Thus, the rôle of glutamine as an N storage compound and ammonia "detoxifier" in many plants extends to the incorporation of photosynthetically reduced N newly produced in Datura leaves; the level of N incorporation into glutamine is apparently dependent on the level of nitrate feeding and the degree of induction of nitrate-reducing enzymes.

Monoclonal and polyclonal antibodies to the interferon-induced phosphoprotein P1 were prepared using protein P1 purified from human amnion U cells as the immunogen. Rabbit antiserum to protein P1 recognized with comparable efficiency P1 both from human U cells and from mouse L929 cells. Immunoprecipitates that contained protein P1 also possessed a protein kinase activity that catalyzed the phosphorylation of protein P1 and the alpha subunit of initiation factor eIF-2. Three BALB/C mouse monoclonal antibodies efficiently recognized human protein P1, but either did not recognize or recognized very poorly P1 from mouse cells. A fourth monoclonal antibody against human P1 recognized mouse P1 with nearly equal efficiency. Immunoprecipitation of human P1 with different sequential combinations of the monoclonal antibodies suggest that two antigenic classes of protein P1 may exist.

The effects of limb movement frequency during walking and running and cycling at 60 and 90 rpm on the ventilatory responses were studied in 19 male subjects. Ten of the subjects were trained runners whereas nine of the subjects were trained cyclists. The runners completed walk and run exercise trials at equal levels of CO2 excretion (VCO2) and low (approximately 60) rpm and high (approximately 90) rpm cycling trials at equal VCO2 levels. The cyclists completed low and high rpm cycling trials at equal VCO2 levels. The cyclists were not tested on the walk/run trials as they had been tested previously and had been shown to have similar ventilatory responses when walking and running at equal VCO2 levels. Minute ventilation (VE), tidal volume (VT), breathing frequency (f), end-tidal CO2 (PETCO2) and O2 (PETO2) tensions, and inspiratory (TI) and expiratory (TE) times were not found to differ significantly between the low and high pedal frequency trials for either the cyclists or the runners. No significant differences were found in estimated arterial CO2 tensions (PaCO2) or estimated alveolar ventilation (VA) between the cycling trials for either the runners or the cyclists. When comparing running to walking, the runners were found to have a greater VE and estimated VA. This was mediated by an increase in f as VT was found to decrease. The increased f was associated with a shortened TI as TE was not significantly different between the walk and run trials. End-tidal CO2 tension and estimated PaCO2 was significantly lower during the run trial as compared to the walk trial. These results suggest some form of neurogenic stimuli influencing ventilation in the runners while running. This same neurogenic influence is not present when cyclists run and when either cyclists or runners exercise on the bicycle. A possible source for the neurogenic stimuli is discussed.

The double-stranded RNA (dsRNA)-dependent protein kinase which catalyzes the phosphorylation of ribosome-associated protein P1 and the alpha subunit of eukaryotic protein synthesis initiation factor 2 (eIF-2) was purified and characterized from mouse fibroblast L929 cells treated with either natural or recombinant interferon and from untreated cells. The dsRNA-dependent P1/eIF-2 alpha kinase was purified at least 1,500-fold from interferon-treated cells; the kinase activity that catalyzed the phosphorylation of eIF-2 alpha copurified with protein P1. The yield of P1/eIF-2 alpha protein kinase activity obtained following purification from cells treated with interferon was about 5-10 times greater than the yield from an equivalent number of untreated cells. The purified protein kinase remained dsRNA dependent. When P1 kinase was activated by dsRNA, a major phosphopeptide designated Xds was phosphorylated; Xds was not phosphorylated from P1 which had not been activated by dsRNA. The apparent native molecular weight of the purified mouse L929 dsRNA-dependent kinase as determined by sedimentation analysis was about 62,000, comparable to the molecular weight of 67,000 determined for denatured L929 phosphoprotein P1 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The purified protein kinase was highly selective for the alpha subunit of protein synthesis initiation factor eIF-2 and endogenous protein P1. Kinase activity was dependent upon Mg2+, and the Km for ATP was determined to be 5 X 10(-6) M. Histones (H1, H2A-B, H3, and H4) and protein synthesis initiation factors other than eIF-2 (eIF-3, eIF-4A, eIF-4B, and eIF-5) were not substrates or were very poor substrates for the purified dsRNA-dependent protein kinase. N-Ethylmaleimide, ethylenediaminetetraacetic acid, AMP, pyrophosphate, spermine, spermidine, and high concentrations of potassium inhibited both P1 and eIF-2 alpha phosphorylation by the purified kinase, whereas ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid and phenanthroline did not significantly affect the phosphorylation of either protein P1 or eIF-2 alpha.

To determine the effects of pregnancy on the cardiovascular responses to immersion and exercise in water, 12 women completed 20 min of immersion and 20 min of bicycle ergometry at 60% predicted VO2max in 30 degrees C water during their 15th, 25th, and 35th week of pregnancy as well as 8-10 weeks post partum. Immersion lowered the resting heart rate approximately 8 bts/min (P less than 0.05). Exercise in water also resulted in a lower heart rate as compared with the same level of exercise on land (132 +/- 4 vs 149 +/- 6 bts/min; P less than 0.05). Both the rest and exercise heart rate responses were independent of duration of pregnancy or pregnancy status. Post partum exercise cardiac output averaged 9.9 +/- 0.4 l/min, significantly lower (P less than 0.05) than the 15th (12.7 +/- 0.5), 25th (14.7 +/- 0.5), or 35th week (15.1 +/- 0.7 l/min). Total peripheral resistance was greatest (P less than 0.05) post partum (657 +/- 29 dyn.s/cm5) compared with either the 15th (515 +/- 27), 25th (407 +/- 18), or 35th week (450 +/- 23). The results indicate that exercise in water lowers the heart rate compared with land exercise at the same metabolic rate. The combined effect of exercise, water, and pregnancy may elevate the cardiac output more than expected on land, but the same general pattern of exercise response will be evident throughout the duration of pregnancy. The results further suggest that water alters the heart rate and blood pressure responses such that land-derived exercise target heart rates should not be used to prescribe exercise intensity in water.

To examine the effects of pregnancy, immersion, and exercise during immersion on pulmonary function and ventilation, 12 women were studied at 15, 25, and 35 wk of pregnancy and 8-10 wk postpartum. Pulmonary function and ventilation were measured under three experimental conditions: after 20 min of rest on land (LR), after 20 min of rest during immersion to the level of the xiphoid (IR), and after 20 min of exercise during immersion at 60% of predicted maximal capacity (IE). Forced vital capacity remained relatively constant, except for a decrease at 15 wk, for the duration of pregnancy. Expiratory reserve volume decreased with a change in the pregnancy status and with the duration of pregnancy. However, the forced vital capacity was maintained by an increase in the inspiratory capacity during pregnancy. Forced expiratory volume for 1 s, expressed as percent of forced vital capacity, did not differ significantly between conditions or as a result of pregnancy. Forced vital capacity was lower during the IR trial compared with LR and IE trials. The decreased forced vital capacity of the IR trials was mediated by a decrease in the expiratory reserve volume. Whereas the inspiratory capacity increased during IR and IE compared with LR, the increase was not large enough to offset the decrease in the expiratory reserve volume. Resting immersion resulted in a significant decrease in maximal voluntary ventilation as did pregnancy. Pregnancy resulted in significant increases in minute ventilation (VE), which were related to increases in the O2 consumption.(ABSTRACT TRUNCATED AT 250 WORDS)

To investigate the influence of stride frequency on ventilation in different subject populations, the ventilatory responses to walking and running at similar metabolic loads were studied in 29 males. Ten of the males were well-trained, highly fit runners (HFR), ten were well-trained, highly fit cyclists (HFC), and nine were healthy low-fit males (LFM) who did not engage in any form of regular exercise. All subjects completed two separate exercise bouts, a level run and an uphill walk, at 90% of their ventilatory threshold. Stride frequency was found to increase by 49% between the walk and run trials. Minute ventilation (VE), tidal volume (VT), breathing frequency (f), end-tibial CO2 tension (PETCO2), end-tidal O2 tension (PETO2), and inspiratory time (TI) were all significantly different (P less than 0.05) between the walk and run trials for the HFR. Minute ventilation and expiratory time (TE) did not differ significantly between the walk and run trials for the HFC; however, VT, f, PETCO2, PETO2, and TI were significantly different. Only PETCO2 and TI were found to be significantly different between the walk and run trials for the LFM. These results suggest that stride frequency affects ventilation to varying degrees dependent upon the subject population and that the mechanisms for the hyperpnea of moderate exercise operating in each of these subject populations involve a complex interaction of many factors.

To determine the consequences of two different stride frequencies on ventilation (VE) at similar levels of carbon dioxide production (VCO2), eleven male subjects performed two work tests on the treadmill. One test involved walking at a speed of 5 km/hr on a 15% grade while the other consisted of running on the treadmill at 9 km/hr on a 0% grade. Running increased stride frequency by 47%. The running and walking tests resulted in similar VCO2 levels, 1.85 +/- .18 and 1.9 +/- .20 l/min respectively, a non-significant difference. Ventilation during running was 43.73 +/- 6.51 l/min and during walking was 43.26 +/- 6.79 l/min, a non-significant difference. In addition the time constants for oxygen consumption (VCO2), VE and VCO2 were measured. The time constants for VCO2 and VE were not found to differ significantly during either the running or walking test. From our results, it can be seen that VE is more closely aligned to the metabolic state rather than stride frequency. In addition, the coupling of VE and VCO2 during the non-steady state is further indicative that ventilation is linked to the metabolic demands of the body.

Large numbers of human cells can be reversibly arrested in mitosis by high-pressure nitrous oxide. The optimum schedule for this arrest requires that the high-pressure block be started around midnight to provide a mitotic population that can be released the next morning to progress in synchrony through the next cell cycle. We describe a simple and safe device which can be set up at the end of the day and automatically exposes the cells to high-pressure nitrous oxide overnight.

The purpose of this investigation was to examine the effects of bat composition (aluminum and wooden), impact location [center of percussion (COP), center of gravity (COG), and end of the bat (E)], and grip firmness [tight (T) and no tension (NT)] on postimpact ball velocity. With the bats placed alternately in NT and T conditions, baseballs were delivered at a speed of 27.1 m.s-1 from a pitching machine positioned 1.5 m from the bat. High-speed photography (400 fps) was performed using a Locam camera positioned 7.54 m from and perpendicular to the principal plane of ball movement. A three-way ANCOVA revealed significant (P less than 0.01) differences in postimpact ball velocity between the three impact locations, with the COP yielding the greatest values, followed by the COG and E. Moreover, there was a significant (P less than 0.01) grip vs bat interaction. A simple-effects procedure revealed the following results: 1) the T grip produced greater (P less than 0.01) velocities than the NT grip across the aluminum (Al) bat; 2) there was no difference (P greater than 0.01) between the T and NT grips across the wooden (W) bat; 3) the W bat produced greater (P less than 0.01) velocities than the Al bat across the NT grip; and 4) there was no difference (P greater than 0.01) between the Al and W bats across the T grip.(ABSTRACT TRUNCATED AT 250 WORDS)

We evaluated the responses of the fetal-maternal unit to immersion and exercise in the water at 15, 25, and 35 weeks' gestation. As seen by underwater ultrasound, fetuses demonstrated body, limb, and breathing movements. Fetal heart rates (FHRs) were normal, and unchanged from those at rest, during maternal exercise in the water at 60% VO2 maximum. In 21 of 23 cases, post-exercise nonstress tests were reactive within ten minutes. There was no uterine activity seen at either 25 or 35 weeks' gestation. Maternal serum alpha-fetoprotein was unaffected at all gestational ages. Neither maternal temperature nor calculated plasma volume changed during exercise. This general lack of effect contrasts with results from other studies involving similar levels of exercise on land. We speculate that the plasma volume expansion with immersion contributes to the normal FHR responses seen in this study.

To determine the effects of wearing graduated compression stockings (GCS) on the exercise response, twelve high fit males served as subjects in a series of two experiments. The first experiment consisted of six subjects performing two tests of maximal oxygen consumption (VO2 max) on a treadmill with and without GCS. The second experiment consisted of six subjects performing three separate three minute tests on a bicycle ergometer at 110% of their VO2 max. The experimental conditions for the three tests were: GCS worn during the test and recovery (GCS), GCS worn only during the test (GCS-O/O) and no stockings worn during either the test or recovery (NO-GCS). Oxygen consumption (VO2) was measured at rest, throughout the duration of all tests and during recovery in both experiments. Blood samples were obtained at rest and at 5, 15, 30, 45 and 60 minutes post exercise in the first experiment and at rest and at 5, 15 and 30 minutes post exercise in the second experiment for the determination of lactate and hematocrit. The use of GCS in the first experiment resulted in no significant difference in VO2 max, recovery VO2 or plasma volume shifts. Lactate values were lower throughout the duration of the recovery period with the 15 minute values being significantly different with the use of GCS. Significant differences in post exercise blood lactate values were found in the second experiment. The GCS trial resulted in significantly less lactate when compared to the GCS-O/O and the NO-GCS trials. There was no significant difference in post exercise lactate values between the NO-GCS and the GCS-O/O trials. Plasma volume changes were not significantly different among trials. Results of both experiments showed recovery lactate values to be lower with the use of GCS. These lower values are not ascribable to plasma volume shifts but rather appear to be due to an inverse gradient created by the GCS resulting in the lactate being retained in the muscular bed.

To examine the effects of advancing pregnancy on metabolic responses, 12 women, who were recruited early in pregnancy, were studied during 20 minutes of immersion in 30 degrees C water, followed by 20 minutes of exercise in the water (60% of predicted maximal capacity) and 20 minutes of lateral supine recovery. Each subject completed the trials during the fifteenth, twenty-fifth, and thirty-fifth weeks of pregnancy, as well as a control period 8 to 10 weeks post partum. Resting oxygen uptake increased with advancing pregnancy. Resting oxygen uptake was higher in the water than on land but was not altered by pregnancy. Exercise oxygen uptakes were similar for all trials, but the work load required to elicit the VO2 decreased during the thirty-fifth week of pregnancy. Exercise heart rates followed the same pattern as oxygen uptake. Lactate concentrations declined with advancing pregnancy after exercise. Blood glucose levels were normal for pregnancy but declined slightly during exercise. Blood triglyceride levels were elevated with exercise, with a tendency to increase with advancing pregnancy. Resting plasma cortisol concentrations increased with pregnancy but remained lower during immersion and exercise. These results suggest that pregnancy significantly alters metabolic responses to exercise in the water.

Illumination at low temperature of the peroxide compound of horseradish peroxidase (HRP-I) causes partial conversion of the haem electronic structure from a ferryl-porphyrin radical species into a low-spin ferric state. Magnetic-c.d. (m.c.d.) and e.p.r. spectral features of the photolysis product are almost identical with those of the alkaline form of ferric HRP, proposed on the basis of its near-i.r. m.c.d. spectrum to be a Fe(III)-OH species. The ferric product of HRP-I photolysis also contains free-radical e.p.r. signals. Conversion of HRP-I into the Fe(III)-OH species, which requires transfer of a proton and two electrons from the protein, is shown to be a two-step process.

A new technique for imaging the intimal surface of arteries through optic fibers has been devised. With the aid of an optical multichannel analyzer, we recorded in real time fluorescence spectra during excitation of the arterial surface with an argon ion laser. Spectral parameters were used to detect atherosclerotic plaques and to discriminate normal tissue from lipid rich and calcified atheromas. By digitizing relative intensity values and the ratios of the peak at 550 nm to that at 520 nm into a gray scale, we generated pseudocolor maps of the arterial wall of 10 human aortas. Specific color distributions were congruent with the distribution of calcified tissue visualized by soft x-ray radiography and the distribution of lipid delineated by staining with Sudan IV. Thus, bidimensional maps obtained by laser spectroscopy can be used to identify the presence and composition of atherosclerotic lesions. Fluorescence imaging may prove to be an important application of laser techniques for the diagnosis and treatment of atherosclerosis.