Endogenous rhythmicity and energy transduction. I. Rhythmicity in adenylate kinase, NAD- and NADP-linked glyceraldehyde-3-phosphate dehydrogenase in Chenopodium rubrum

1973 ◽  
Vol 51 (7) ◽  
pp. 1355-1367 ◽  
Author(s):  
Silvia Frosch ◽  
Edgar Wagner ◽  
Bruce G. Cumming
Keyword(s):  
Adenylate Kinase ◽  
Strong Dependence ◽  
Phase Relationship ◽  
Spatial Separation ◽  
Period Length ◽  
Base Line ◽  
Glucose Feeding ◽  
Endogenous Rhythmicity ◽  
Time Courses ◽  
Cellular Compartments

It is demonstrated that adenylate kinase (AK) as well as NAD- and NADP-dependent glyceraldehyde-3-phosphate dehydrogenase (NAD- and NADP-GPD) display an endogenous rhythm in the time courses of their activities in constant conditions. The rhythm in AK activity has a period length of close to 30 h with two 15-h subpeaks in each 30-h period. The cycles in NAD- and NADP-GPD activity have a period length of 15 h and have an inverse phase relationship. The amplitude of the rhythm at the end of a dark period provides the base line for increase in enzyme activity in light after darkness. The increase in light is essentially the same regardless of the length of darkness. There is a differential effect of glucose feeding in light as compared to darkness. In darkness, glucose feeding increased NAD-GPD and AK activity but had no effect on NADP-GPD activity. In light, glucose caused an increase in NAD-GPD as well as AK activity over the Hoagland's controls but not in NADP-GPD, which was less than in the controls.The results are discussed in relation to a hypothesis assuming that endogenous rhythmicity might be due to the spatial separation of energy production and utilization in different cellular compartments with strong dependence on key coenzymes.

Endogenous rhythmicity and energy transduction. III. Time course of phytochrome action in adenylate kinase, NAD- and NADP-linked glyceraldehyde-3-phosphate dehydrogenase in Chenopodium rubrum

1973 ◽  
Vol 51 (8) ◽  
pp. 1529-1535 ◽  
Author(s):  
Silvia Frosch ◽  
Edgar Wagner
Keyword(s):  
Enzyme Activity ◽  
Adenylate Kinase ◽  
Time Course ◽  
Functional Relationship ◽  
Relative Concentration ◽  
Red Light ◽  
Endogenous Rhythm ◽  
Activated State ◽  
Endogenous Rhythmicity ◽  
Time Courses

Evidence is presented that phytochrome triggers and maintains the increase in adenylate kinase (AK) as well as NAD- and NADP-dependent glyceraldehyde-3-phosphate dehydrogenase (NAD- and NADP-GPD) activity. After cyclic germination conditions, the time courses of all three enzymes display an endogenous rhythmic increase of their activities in constant far-red light. After germination in constant conditions, NAD- and NADP-GPD activities displayed no rhythm, while AK activity increased rhythmically. Such readiness of AK activity to oscillate was taken as indication of a close functional relationship between the control mechanism(s) of the endogenous rhythm and AK activities. The time courses in NADP-GPD activity demonstrated that phytochrome acted as an on-off switch for the increase in enzyme activity and also controlled enzyme activity depending on the relative concentration of active phytochrome. There is evidence for a function of phytochrome in the "ground state" as well as in an "activated state."It is suggested that phytochrome could be coupled to endogenous rhythmicity by modulating the redox potential of the cell, while phytochrome action itself would be timed by the endogenous rhythm.

Endogenous rhythmicity and energy transduction. II. Phytochrome action and the conditioning of rhythmicity of adenylate kinase, NAD- and NADP-linked glyceraldehyde-3-phosphate dehydrogenase in Chenopodium rubrum by temperature and light intensity cycles during germination

1973 ◽  
Vol 51 (8) ◽  
pp. 1521-1528 ◽  
Author(s):  
Silvia Frosch ◽  
Edgar Wagner
Keyword(s):  
Light Intensity ◽  
Adenylate Kinase ◽  
Dark Period ◽  
Energy Transduction ◽  
Endogenous Rhythm ◽  
Chenopodium Rubrum ◽  
Germination Period ◽  
Endogenous Rhythmicity ◽  
Free Running

Endogenous rhythmicity in NADP- and NAD-linked glyceraldehyde-3-phosphate dehydrogenase (NADP- and NAD-GPD) as well as in adenylate kinase (AK) activity is initiated or synchronized during cyclic germination conditions of light and temperature, and is free-running in a dark period interrupting continuous light.There is phytochrome control of the amplitude in NADP-GPD and AK oscillations during the first hours of darkness if the beginning of the dark period is in phase with the beginning of the germination period. The endogenous rhythm acts like an "on-off" switch for potential phytochrome action. The results are discussed in relation to daily photoperiodic cycles.

Uptake and incorporation of phosphate by frog gastric mucosa

1980 ◽  
Vol 239 (5) ◽  
pp. G411-G417
Author(s):  
R. P. Durbin ◽  
D. Hanzel
Keyword(s):  
Gastric Mucosa ◽  
Acid Secretion ◽  
Adenylate Kinase ◽  
Acid Production ◽  
Inorganic Phosphate ◽  
Strong Dependence ◽  
Creatine Phosphate ◽  
High Energy ◽  
Alkaline Ph

Labeled inorganic phosphate (32Pi) was used to follow uptake and incorporation of phosphate into high-energy intermediates of isolated bullfrog gastric mucosa. Dependence of uptake on levels of external Pi showed both saturable nonsaturable components. Measurements at 25 microM Pi, a level at which the saturable component was predominant, showed a strong dependence of Pi uptake on external Na+ and pH. Labeling of adenosine 5'-triphosphate (ATP) and creatine phosphate was rapid, followed by labeling of adenosine 5'-diphosphate, probably by way of adenylate kinase. Both alkaline nutrient pH and the uncoupling agent, dinitrophenol, reduced labeling of ATP with a concomitant inhibition of acid secretion. A feasible interpretation is that dinitrophenol acts by diminishing mitochondrial production of ATP, whereas alkaline pH reduces the utilization of ATP by the K+-ATPase considered to be responsible for acid production. The results thus agree with the hypothesis that ATP is the immediate substrate for secretion: only a part of the tissue ATP is directly available to the acid-producing mechanism, however.

Changes of sympathetic nerve activity induced by 2-deoxy-D-glucose infusion in humans

1989 ◽  
Vol 256 (6) ◽  
pp. E714-E720 ◽  
Author(s):  
J. Fagius ◽  
C. Berne
Keyword(s):  
Sympathetic Activity ◽  
Blood Levels ◽  
Minor Role ◽  
Base Line ◽  
Glucose Levels ◽  
Muscle Nerve ◽  
Sudomotor Activity ◽  
Time Courses ◽  
A Minor ◽  
Line Level

Microelectrode recording of sympathetic signals in the peroneal nerve was performed in 14 healthy volunteers following infusion of 2-deoxy-D-glucose (50 ml/kg body wt). Heart rate, blood pressure, body temperature, hematocrit, and blood levels of glucose, insulin, and catecholamines were monitored. Muscle nerve sympathetic activity (MSA), which is involved in cardiovascular homeostasis, increased significantly from a base-line level of 19.9 +/- 4.5 (mean +/- SE) bursts/min to a peak 30 min after the start of the infusion of 33.1 +/- 5.1 bursts/min. Skin nerve sympathetic activity (SSA), which is a mixture of sudomotor and vasoconstrictor signals, also increased to a peak at 30 min. The impulse pattern of SSA suggested that the increase involved mainly sudomotor activity, with simultaneous inhibition of vasoconstrictor signals. The time courses of MSA and the circulatory responses suggested that the increase in MSA was not a baroreceptor-induced counteraction of the cardiovascular changes during glucopenia. The responses of MSA and SSA were remarkably similar to those observed previously during insulin-induced hypoglycemia. The relationship between changes of sympathetic outflow, glucose levels, and insulin levels in the present study indicates that the effects observed are consequences of central nervous system glucopenia, with insulin playing a minor role. It is concluded that the sympathoadrenal system responds in a markedly differentiated way to glucopenia.

Interstitial fluid volumes and albumin spaces in pulmonary oxygen toxicity

1984 ◽  
Vol 57 (6) ◽  
pp. 1767-1772 ◽  
Author(s):  
S. Matalon ◽  
E. A. Egan
Keyword(s):  
Skeletal Muscle ◽  
Pulmonary Edema ◽  
Interstitial Fluid ◽  
Oxygen Toxicity ◽  
Systemic Circulation ◽  
Base Line ◽  
Epithelial Permeability ◽  
Bovine Albumin ◽  
Alveolar Epithelial ◽  
Cellular Compartments

In rabbits exposed to 100% O2 at 1 ATA from 48 to 72 h, we measured the accumulation of intravenously injected 125I-bovine albumin, [57Co]cyanocobalamin, and 51Cr-erythrocytes in the intestine, skeletal muscle, heart, and lungs. From these data, we calculated the extravascular albumin and cyanocobalamin spaces (EVAS, EVECS) and the partition of water among vascular, interstitial, and cellular compartments in these organs. All variables remained at their base-line levels at 48 h in O2. At 64-66 h, the lung EVECS remained unchanged, but its EVAS increased by 210%. This change occurred after the previously documented increase of the alveolar epithelial permeability to solute and of the pulmonary conductance to water but before the appearance of pulmonary edema and arterial hypoxemia. The only change in the systemic circulation was a 17% increase of the heart EVAS. The increased heart and lung EVAS values, in the absence of any fluid volume shifts, are consistent with damage to the tissue polysaccharides of these organs by the toxic O2 species.

CBED analysis of impurity distributions in AlN

1990 ◽  
Vol 48 (4) ◽  
pp. 214-215
Author(s):  
Daniel Callahan ◽  
G. Thomas
Keyword(s):  
Aluminum Nitride ◽  
Bulk Material ◽  
Strong Dependence ◽  
Lattice Parameter ◽  
Promising Technique ◽  
Nitride Ceramics ◽  
Surface Phases ◽  
Convergent Beam ◽  
Oxygen Impurities

Oxygen impurities may significantly influence the properties of nitride ceramics with a strong dependence on the microstructural distribution of the impurity. For example, amorphous oxygen-rich grain boundary phases are well-known to cause high-temperature mechanical strength degradation in silicon nitride whereas solutionized oxygen is known to decrease the thermal conductivity of aluminum nitride. Microanalytical characterization of these impurities by spectral methods in the AEM is complicated by reactions which form oxygen-rich surface phases not representative of the bulk material. Furthermore, the impurity concentrations found in higher quality ceramics may be too low to measure by EDS or PEELS. Consequently an alternate method for the characterization of impurities in these ceramics has been investigated.Convergent beam electron diffraction (CBED) is a promising technique for the study of impurity distributions in aluminum nitride ceramics. Oxygen is known to enter into stoichiometric solutions with AIN with a consequent decrease in lattice parameter.

The Effect of Nonlinear Amplitude Growth on the Speech Perception Benefits Provided by a Single-Sided Vocoder

2019 ◽  
Vol 62 (3) ◽  
pp. 745-757 ◽  
Author(s):  
Jessica M. Wess ◽  
Joshua G. W. Bernstein
Keyword(s):  
Transfer Functions ◽  
Spatial Configuration ◽  
Free Field ◽  
Spatial Separation ◽  
Compression And Expansion ◽  
Interaural Difference ◽  
Interaural Differences ◽  
Single Sided Deafness ◽  
Perceptual Separation ◽  
Loudness Growth

PurposeFor listeners with single-sided deafness, a cochlear implant (CI) can improve speech understanding by giving the listener access to the ear with the better target-to-masker ratio (TMR; head shadow) or by providing interaural difference cues to facilitate the perceptual separation of concurrent talkers (squelch). CI simulations presented to listeners with normal hearing examined how these benefits could be affected by interaural differences in loudness growth in a speech-on-speech masking task.MethodExperiment 1 examined a target–masker spatial configuration where the vocoded ear had a poorer TMR than the nonvocoded ear. Experiment 2 examined the reverse configuration. Generic head-related transfer functions simulated free-field listening. Compression or expansion was applied independently to each vocoder channel (power-law exponents: 0.25, 0.5, 1, 1.5, or 2).ResultsCompression reduced the benefit provided by the vocoder ear in both experiments. There was some evidence that expansion increased squelch in Experiment 1 but reduced the benefit in Experiment 2 where the vocoder ear provided a combination of head-shadow and squelch benefits.ConclusionsThe effects of compression and expansion are interpreted in terms of envelope distortion and changes in the vocoded-ear TMR (for head shadow) or changes in perceived target–masker spatial separation (for squelch). The compression parameter is a candidate for clinical optimization to improve single-sided deafness CI outcomes.

The Endothelial Cell and the Factor VIII Bypassing Activity of Prothrombin Complex Concentrate

1988 ◽  
Vol 60 (02) ◽  
pp. 226-229 ◽  
Author(s):  
Jerome M Teitel ◽  
Hong-Yu Ni ◽  
John J Freedman ◽  
M Bernadette Garvey
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Factor Viii ◽  
Prothrombin Complex Concentrate ◽  
Vascular Endothelial Cells ◽  
Vascular Endothelial ◽  
Monolayer Cultures ◽  
Coagulant Activity ◽  
Time Courses ◽  
Privileged Site

SummarySome classical hemophiliacs have a paradoxical hemostatic response to prothrombin complex concentrate (PCC). We hypothesized that vascular endothelial cells (EC) may contribute to this “factor VIII bypassing activity”. When PCC were incubated with suspensions or monolayer cultures of EC, they acquired the ability to partially bypass the defect of factor VIII deficient plasma. This factor VIII bypassing activity distributed with EC and not with the supernatant PCC, and was not a general property of intravascular cells. The effect of PCC was even more dramatic on fixed EC monolayers, which became procoagulant after incubation with PCC. The time courses of association and dissociation of the PCC-derived factor VIII bypassing activity of fixed and viable EC monolayers were both rapid. We conclude that EC may provide a privileged site for sequestration of constituents of PCC which express coagulant activity and which bypass the abnormality of factor VIII deficient plasma.

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