Decline In Flow Rate Research Articles

Catabolic repression of hydrogenase synthesis in Ectothiorhodospira shaposhnikovii

The hydrogenase activity of purple sulfur bacterium Ectothiorhodospira shaposhnikovii was minimal when grown in acetate excess. Molecular hydrogen evolved to the nitrogenase activity of cells cultivated in chemostat under ammonium limitation did not increase the hydrogenase activity. Under acetate limitation, the flow rate decline increased the hydrogenase activity of cells and simultaneously the intracellular content of cyclic adenosine-5′-monophospate. Therefore, the hydrogenase synthesis by E. shaposhnikovii is regulated by catabolic repression.

Catabolic repression of hydrogenase synthesis in Ectothiorhodospira shaposhnikovii

The hydrogenase activity of purple sulfur bacterium Ectothiorhodospira shaposhnikovii was minimal when grown in acetate excess. Molecular hydrogen evolved to the nitrogenase activity of cells cultivated in chemostat under ammonium limitation did not increase the hydrogenase activity. Under acetate limitation, the flow rate decline increased the hydrogenase activity of cells and simultaneously the intracellular content of cyclic adenosine-5′-monophospate. Therefore, the hydrogenase synthesis by E. shaposhnikovii is regulated by catabolic repression.

Maximum and average urine flow rates in normal male and female populations--the Liverpool nomograms.

The study of voiding in men and women has been handicapped by the lack of a normal reference range covering urinary flow rates over a wide range of voided volumes. Normal volunteers (331 males and 249 females) were studied. Each voided once into a calibrated Dantec Urodyn 1000 mictiograph. On a second occasion 282 men and 46 women voided. The maximum and average urine flow rates of the first voids in both sexes were compared with the respective voided volumes. Nomogram charts, in centile form, for both the maximum and average urine flow rates were constructed using statistical transformations of the data. Males showed a significant decline in both urinary flow rates with age, although there was no statistically significant variation in either urine flow rate with respect to first versus repeated voiding. Females showed no statistically significant variation in either urine flow rate with respect to age, parity or first versus repeated voiding. The maximum and average urine flow rates in both sexes showed an equally strong relationship to voided volume. No artificial restriction of voided volume, e.g. minimum 200 ml, appeared appropriate. These nomograms offer reference ranges for both maximum and average urinary flow rates in both sexes covering a wide range of voided volumes (15-600 ml).

Theophylline prevents the hypoxemia-induced renal hemodynamic changes in rabbits

The acute renal effects of hypoxemia and the ability of theophylline to prevent these effects were assessed in anesthetized and mechanically-ventilated newborn and adult rabbits. Renal blood flow (RBF) and glomerular filtration rate (GFR) were determined by the clearance of para-aminohippuric acid and inulin, respectively. Each animal acted as his own control. In 14 newborn rabbits (group 1), hypoxemia was significantly associated with a fall in GFR (-22 +/- 6%) and filtration fraction (-17 +/- 3%) and with an increase in renal vascular resistance (+13 +/- 6%). Hypoxemia also induced a significant decline in GFR (-27 +/- 6%) and RBF (-29 +/- 6%) in 7 adult rabbits (group 3). Intravenous theophylline (0.5 mg/kg) completely prevented the hypoxemia-induced changes in GFR, filtration fraction (FF) and renal vascular resistance (RVR) in 8 newborn rabbits (group 2). An intravenous dose of 2.4 mg theophylline given after the induction of hypoxemia partially reversed the drop in GFR in adult rabbits (group 3). Separate renal functions were studied in 8 additional adult rabbits (group 4). Low-dose theophylline (27 micrograms/min) infused intra-arterially in the left kidney partially prevented the hypoxemia-induced decline in urine flow rate, GFR, RBF, FF as well as the increase in renal vascular resistance. The beneficial effects of theophylline could be mediated by its adenosine antagonistic properties.

The hemodynamic consequences of hemorrhage and hypernatremia in two amphibians.

1. Graded hypovolemia was induced by hemorrhagic blood loss and graded hypernatremia by salt load in the toad, Bufo marinus, and the bullfrog, Rana catesbeiana. Maximal blood flow rates in the systemic arches and arterial and venous pressures were measured during activity after each stress. 2. Maximal blood flow rates in the B. marinus did not decline until blood loss exceeded 5% of initial body mass. In R. catesbeiana, losses of 2% initial body mass caused a decline (Fig. 1). 3. Maximal heart rates did not change with hemorrhage (Fig. 2). The decline in blood flow rates with hemorrhage was due to declining pulse volumes in both species (Fig. 3). 4. Arteriovenous pressure difference declined with hemorrhage in both species (Fig. 4). Peripheral resistance increased with hemorrhage in parallel with compromised blood flow rates (Fig. 5). 5. Plasma sodium concentration slightly increased with hemorrhage, while plasma protein concentration and hematocrit declined. Lymphatic compensation for hemorrhagic loss is indicated in both species (Fig. 6). 6. Induced hypernatremia compromised blood flow rates in both species at plasma sodium concentrations above 175 mM. The decline in flow rates was principally a result of a decrease in pulse volume, though maximal heart rates also declined (Figs. 2, 3, 7). 7. Induced hypernatremia had no effect on the arteriovenous pressure difference in B. marinus but caused it to decline in R. catesbeiana. Peripheral resistance increased in only B. marinus but not R. catesbeiana (Figs. 4, 5). Hematocrit did not change with salt load, indicative of a constant vascular volume.

Terbutaline sustained-release tablets in nocturnal asthma—a placebo-controlled comparison between a high and a low evening dose

The effects of oral treatment with terbutaline sustained-release (SR) tablets (Bricanyl ® Depot) were studied in nine patients who had bronchial asthma and marked diurnal variation in ventilatory function. In a randomized and double-blind study, the patients were treated with terbutaline SR 7.5 mg b.i.d., terbutaline SR 7.5 mg in the morning and 15 mg in the evening and terbutaline SR placebo b.i.d. Each treatment was given for 1 week. The nocturnal decline in the peak expiratory flow rate (PEFR) was 45% during the placebo period, 27% after the lower and 22% after the higher terbutaline SR evening dose ( P<0.01 for both treatments compared to placebo). The mean morning PEFR was significantly higher with the high evening dose than with the low evening dose ( P<0.01). Mild to moderate side effects were noted. The sustained-release preparation of terbutaline seems to be of clinical value in preventing or relieving nocturnal asthma and early morning dipping. The flexible dose technique, with a higher evening dose, results in further improvements in these patients.

Obliterative Bronchiolitis After Heart-Lung Transplantation: Apparent Arrest by Augmented Immunosuppression

Obliterative bronchiolitis has been the major complication in long-term survivors of human heart-lung transplantation at our institution. We have assessed the effect of the introduction of a third immunosuppressive agent, azathioprine, on the rate of decline in airflow variables in eight heart-lung transplant recipients with obliterative bronchiolitis, and have compared this rate with that in five patients who did not receive augmented immunosuppressive therapy. Specifically, the rate of decline in forced expiratory flow rate between 25% and 75% of vital capacity improved considerably after institution of this therapy (-5.25 +/- 2.85 compared with -0.27 +/- 0.66 [mean +/- SD]; p less than 0.005), whereas the effect on the ratio of forced expiratory volume in one second to forced vital capacity was more modest (-3.61 +/- 1.52 compared with -0.54 +/- 0.93; p less than 0.005). The rate of decline in airflow variables was similar in both groups before the institution of therapy with azathioprine. These results show that augmented immunosuppressive therapy is capable of slowing the rate of progression of obliterative bronchiolitis in this population; they also suggest that the obliterative bronchiolitis may represent a form of chronic pulmonary allograft rejection.

Particle-induced Coronary Vasoconstriction in the Rat Heart: Pharmacological Investigation of Underlying Mechanisms

An isolated perfused rat heart preparation has been used in an attempt to define the mechanisms underlying the coronary vasoconstriction associated with the intraarterial infusion of cardioplegic solutions containing contaminant particles. Coronary infusion of commercially available intravenous solutions, compounded to create the St. Thomas' cardioplegic solution, resulted in a 40.3 +/- 1.9% decline in coronary flow rate at the end of a 20-minute period of infusion. Filtration of the solution through a 0.8 micron filter reduced this decline in flow rate to 23.4 +/- 2.3% of its control value. Inclusion of the 5HT2 receptor antagonist ketanserin (1.0 nanomoles/l), in the unfiltered cardioplegic solution, afforded the same protection as filtration. Inclusion of 5HT (0.1 micromole/l) in a filtered cardioplegic solution resulted in a reduction of coronary flow (49.7 +/- 1.9%) greater than that seen with the unfiltered solution. Studies with antagonists of the histamine receptor (mepyramine and cimetidine) and agonists and antagonists of adrenergic receptors suggested that, although involved in the control of vascular tone, these receptor systems are unlikely to be involved in the process of particle-induced vasoconstriction. Arguments are presented that 5 HT and its receptors may play a critical role and the hypothesis is advanced that particle-induced focal endothelial injury may be the primary lesion in a complex sequence of events leading to induction of transient vasoconstriction.

Pulmonary Function in Normal Subjects and Patients with Sarcoidosis after Bronchoalveolar Lavage

To determine if fiberoptic bronchoscopy (FOB) with bronchoalveolar lavage impairs pulmonary function in normal subjects or those with sarcoidosis, we measured flow-volume loops, thoracic gas volume, and single breath carbon monoxide diffusing capacity before, one half hour and 24 hours after lavage. We studied 12 normal subjects; six underwent a large volume lavage (approximately 500 ml saline instilled), and six underwent a small volume lavage (approximately 175 ml). Five subjects with sarcoidosis also had a small volume lavage. Six control subjects underwent FOB without lavage. The FOB alone produced no significant changes in pulmonary function one half hour after the procedure. Small volume lavage in normal subjects produced no change except for a 16.3 +/- 5.1 percent (mean- +/- SEM) decline in peak expiratory flow rate (p less than .05) one half hour postlavage which returned to normal by 24 hours. This contrasts with sarcoidosis subjects in whom forced expiratory volume in one second, peak expiratory flow rate, and vital capacity declined by 20 +/- 4.8 percent, 26.7 +/- 7.3 percent, and 15.2 +/- 4.1 percent, respectively, (all p less than 0.05) one half hour postlavage. No change occurred in total lung capacity or diffusing capacity. Only with large volume lavage did decrements in lung function occur in normal patients that were comparable to those seen in the sarcoidosis subjects. Our findings suggest that bronchoalveolar lavage in normal patients can be associated with a significant and volume-related decline in pulmonary function and that in subjects with sarcoidosis, the deterioration is more pronounced.

The role of endogenous opioids in the ventilatory response to acute flow-resistive loads.

The ability of acute, short-term, inspiratory flow-resistive loading to generate endogenous opioids was studied in 6 unanesthetized goats. Endogenous opioid generation was assessed by measurement of immunoreactive beta-endorphin levels in the cisternal cerebrospinal fluid (CSF) after high (80 cm H2O/L/s) and moderate (50 cm H2O/L/s) resistive loading. The results show that CSF levels of beta-endorphin were significantly increased by both the high and moderate resistive loads (40 +/- 4 SEM pg/ml and 33.7 +/- 3.4 pg/ml, respectively) when compared with the same animals during unloaded control conditions (19.5 +/- 3.8 pg/ml). Both levels of loading also caused a significant progressive decline in tidal volume (to 82 +/- 8 and 89 +/- 8% of baseline tidal volume with the high and moderate loads, respectively). Naloxone administration (0.1 mg/kg) resulted in a transient but significant increase in tidal volume from the sixth through the twentieth minute (to 37 +/- 5 and 34 +/- 5% peak tidal volume increase with high and moderate loads, respectively). In addition, there was a significant correlation between the percent decline in tidal volume and mean inspiratory flow rate after loading and the level of beta-endorphin in the cisternal CSF. We conclude that relatively short-term, high-level, inspiratory flow-resistive loading results in elaboration of endogenous opioids within the central nervous system and that these opioids play a role in the progressive decline in tidal volume and mean inspiratory flow rate exhibited during these conditions.

Forearm blood flow responding prior to voluntary isometric contraction.

ABSTRACTSrain‐gauge plethysmography was used to study phasic forearm blood flow (FBF) responding, which has been presumed to occur in human subjects prior to voluntary muscular contraction. In a two‐group design, 10 subjects performed a 7‐s, fixed‐foreperiod, reaction‐time (RT) task in which static handgrip was the required RT response; 10 additional subjects in a High Incentive (HI) condition performed a more stressful delayed avoidance task. Bilateral FBF and HR were computer‐sampled over the preparatory interval (PI) and transformed into second‐by‐second measures. Mean FBF estimates were also obtained by averaging over the entire PI. HI subjects were found to manifest significantly greater mean FBF prior tro motor responding than did subjects performing the nonstressful RT taks. Such preparatory FBF responding was task‐specific, occurring only in the Arm to be performing the signalled RT response. Furthermore, this task‐specific, phasic increase in averaged mean FBF was observed to occur in subjects' left and right arms. Trend analysis and visual inspection of second‐by‐second FBF waveforms demonstrated a gradual decline in flow rate over the course of the preparatory interval under all experimental conditions. HR responding manifested the characteristic triphasic waveforms, with higher heart rate and augmentation of acceleratory and terminal deceleratory components exhibited by the HI group. the findings suggest that human phasic FBF responding can be influenced by motoric and motivational factors as well as by demands for sensory intake behavior.

A comparison of risk selections

Studies documenting the increased incidence of exercise-induced bronchospasm (EIB) in figure skaters have employed a method that incorporates on-ice exercise with rink-side spirometry. The literature suggests that bronchial provocation challenge testing is better than exercise testing for identifying EIB. To test this hypothesis in figure skaters, a unique athletic population that trains and competes in cold air, we compared these two methods in the same individuals.Two challenge tests were performed on a group of competitive figure skaters (n = 29, 26 female subjects; mean ± SD age = 12.3 ± 3.5 years): (1) rink-side (temperature = 14°C, humidity = 60%) spirometry before and 1, 5, 10, and 15 min after 5 min of intense skating; and (2) eucapnic voluntary hyperventilation (EVH), breathing 5% CO2, 21% O2, balance N2 at a rate of 60% of maximum voluntary ventilation (not to exceed 70 L/min) for 5 min (temperature = 18°C, humidity = 50%), with an identical pretest and posttest spirometry schedule. EIB was defined as at least one of the following: a ≥1 0% decline in Fev1; a≥ 20% decline in maximum midexpiratory flow rate; or a ≥ 25% decline in peak expiratory flow rate.Sixteen of 29 skaters (55%) developed EIB: 9 were positive by on-ice testing; 12 were positive by EVH testing; 5 were positive on both tests; on-ice testing missed 7 skaters with EIB; EVH testing missed 4 with EIB.In the group of figure skaters studied, EVH challenge testing was better at identifying EIB than on-ice exercise testing. However, these data suggest that evaluation for EIB in athletes who train and compete in the cold should include exercise testing in cold air along with a challenge test such as EVH to increase the yield of positive responders.

Alterations in Pulmonary Function Following Respiratory Viral Infection

Respiratory viral illness is a major cause of morbidity in both adults and children. This report focuses on both the acute and chronic effects on respiratory function of these ubiquitous infections. Infant airways are particularly vulnerable due to the relatively low conductance in immature peripheral airways. Bronchiolitis, caused predominantly by respiratory syncytial virus, is the most important of these viral illnesses and is emerging as a major risk factor for the subsequent development of obstructive airway disease in adults, possibly by interference with normal alveolar proliferation. The basic pathogenic mechanism involved in adult respiratory viral infection is bronchial hyperreactivity, presumably secondary to epithelial damage and resultant sensitization of rapidly adapting airway receptors. In addition, there may be virus-related alterations in the autonomic and humoral regulation of airway tone. Viral infections may alter the effects of common air pollutants on respiratory function.

The effect of air embolism on renal preservation.

Air embolism to the kidneys was induced in dogs during an ex vivo perfusion preservation period using cryoprecipitated plasma to demonstrate the effect of air embolism on the function of the preserved kidneys. A sharp decline in plasma flow rate was observed after air was infused, but the rate returned to the preembolism range in 60 minutes. Differences in posttransplant serum creatinine levels between the control and air embolism groups were not statistically significant. No deleterious effect was demonstrated on the final function of preserved kidneys by infusion of air. Three cadaver kidneys that accidentally sustained air embolism during the perfusion preservation period were transplanted. Although an initial period of acute tubular necrosis developed in these three kidneys, two kidneys regained good renal function and the third kidney was removed because of irreversible rejction. This study demonstrates that kidneys that sustain air embolism can be used for clinical transplantation.

Some Considerations on Bottom Hole Pressure Build-up Phenomena-(I)

Approximately linear or exponential flow rate decline is often reported at the conventional DST or Flow Test. At the present study, a new practical method based on theoretical considerations is brought forward for pressure build-up analysis in such cases. Its characteristic feature exists in plotting the observed pressure data vs the appropriate functions different from that of logarithmic type as in the conventional methods, which are derived, taking the flow period, shut-in period and decline rate into considerations, and the numerical values of which can be easily known on the prepared charts. This new method provides with the simultaneous evaluation of prevailing reservoir pressure, transmissibility and flow decline rate, even though the last is previously unkown, and it seems to the author that better results can be obtained by the new method than by other conventional ones. The evaluation of skin factor is also treated at the present study. As a matter of course, the skin factor formula for variable rate case differs from the conventional one for constant rate case and the accuracy of results by the latter is theoretically discussed. It is considered that the modification for the skin factor formula has its practical meaning especially at DST, because the final flow rate can't generally be known. The full contents will appear in instalments.

The effects of air ions of the living mammalian trachea.

Studies on the effects of air ions on the functional efficiency of the extirpated tracheal strip have been extended to the trachea of the living rabbit, rat, and mouse. Animals exposed to high mobility (+) air ions administered via a tracheotomy aperture displayed: (a) Decreased ciliary activity. (b) Decline in mucus flow rate, sometimes reversed by prolonged exposure to (+) ions; a frequent drop in the volume of mucous secretion. (c) Contraction of the membranous posterior tracheal wall. (d) Increased vulnerability to trauma of cilia and mucosal blood vessels. Similar treatment with (-) air ions reversed (+) ion effects on ciliary activity, mucus flow, contraction of the tracheal smooth muscle. Continued (-) ion treatment raised the ciliary rate (invariably) and the mucus flow rate (often) above their initial levels. (+) Air ions administered to unoperated resting mice and rats increased the respiratory rate; (-) ions reversed this effect. Long exposure of unoperated ambulatory mice to (+) air ions produced: (a) Decreased ciliary activity. (b) No clear cut effect on mucus flow. (c) Contraction of the posterior tracheal wall. (d) Increased vulnerability of the mucosa to trauma. (-) Air ions increased ciliary activity but had no clear-cut effect on the mucus flow rate.