Respiration Index Research Articles

A spectral approach for heart rate fluctuations analysis

IN order to investigate the autonomic control of the cardiovascular system power spectral analysis of the R–R interval was applied to 24-h Holter monitoring in 6 subjects. In 2 subjects the analysis was also applied to the 24-h respiratory signal and in 4 to the R–R interval and respiration during spirometric tests. Power spectral analysis was also applied to R-wave amplitude variability, a potential index of respiration, and compared to the respiratory signal when available. Results showed 3 major frequency components of heart rate variability: a low frequency around 0.04 Hz, a mid frequency around 0.10 Hz and a high frequency around 0.25 Hz. The high-frequency component of the spectrum was consistently evident during sleep and appeared to be related to respiration. R-wave amplitude variability appeared to reflect respiratory frequencies in all instances.

Influence of feed intake and starvation on the magnitude of Na+,K+-ATPase(EC 3.6.1.3)-dependent respiration in duodenal mucosa of sheep.

Oxygen consumption and Na+,K+-ATPase(EC 3.6.1.3)-dependent (ouabain-sensitive) and -independent respiration were measured for duodenal mucosa biopsies from 10-month-old sheep given two levels of digestible energy (DE) intake (7.6-7.7 and 14.8 MJ lucerne (Medicago sativa) pellets/d) and following 48 h of starvation. The mucosal biopsies were determined to be structurally intact and free of adherent bacteria on histological and scanning-electron-microscope examinations. The use of D-glucose as a substrate during incubations did not elevate (P greater than 0.05) the respiration indices of the biopsies over those measured during acetate incubations. Glucose uptake did not (P greater than 0.05) influence the Na+,K+-ATPase-dependent respiration of the mucosal biopsies. Na+,K+-ATPase-dependent respiration accounted for 50% of the total O2 consumption of the mucosal biopsies of sheep given the lower level of DE. Total O2 consumption of the duodenal mucosa was not (P greater than 0.05) increased when sheep were given the higher level of DE but Na+,K+-ATPase-dependent respiration of the mucosa was elevated (P less than 0.01) by 37% during this period. When sheep were starved for 48 h, total O2 consumption of the mucosal biopsies was not (P greater than 0.05) affected, however, Na+,K+-ATPase-dependent respiration of the biopsies dropped (P less than 0.01) by 45%. Na+,K+-ATPase-dependent respiration accounted for 61.3% of the O2 uptakes of mucosa from the sheep given the higher level of DE and 28.3% of the O2 uptake of mucosa from fasted sheep.

Dinitrogen fixation by Azotobacter chroococcum and its isocitrate dehydrogenase activity: A quick method for screening nitrogen fixing strains.

Nitrogenase activity in the rhizosphere of sugarcane (Saccharum officinarum Linn.), and its associated soil was measured by reduction of acetylene. Zero order kinetics and first order kinetics of acetylene reduction (C2H2→C2H4) were used to describe the activity of N2 fixers from these soils. Arranged in descending order of nitrogen-fixing (acetylene-reducing) potential, the sites examined were highland (arable), mesic meadow, peat polygon trough, transition zone between mesic meadow and peat polygon trough, lowland (flooded with water) and virgin flooded land. On most of the land, sugarcane has been under cultivation for centuries. In total, 9 acetylene reducers were isolated, the remaining being oligonitrophiles. In addition to using the saturation kinetic values to describe the activity of dinitrogen fixers, first order kinetics of several potential energy substrates were also compared. Carbohydrate concentrations (glucose, maltose, arabinose, mannose and raffinose) between 25 and 100μg/ml were used since the Michaelis-Menten plot indicates that between this range first order kinetics were measured. The results indicated that various carbohydrate additions had different effects on C2H2 reduction.Because of the relatively high temperature requirements for Azotobacter chroococcum development, tropical areas appear more favorable for a higher incidence of this bacterium. Optimal temperatures for acetylene reduction were between 25°-30°. Acetylene reduction was pH-dependent, the optimum occurring between pH 6.4-7.5. Nitrogenase activity was almost completely inhibited by air and anaerobic conditions, and was optimum at around pO2 0.06atm. The reduction of 2, 3, 5-triphenyl tretrazolium chloride to triphenyl formazan has been used to estimate the dehydrogenase activity of Azotobacter strains in vivo. A significant correlation has been obtained between isocitrate dehydrogenase reactions and the oxygen uptake of a number of isolates; the production of the formazan was used as an index of endogenous respiration. A similar relationship was also obtained between dehydrogenase reactions and bacterial numbers. A relationship between acetylene reduced per gram of organic carbon utilized and the dehydrogenase reactions has been recorded. This investigation also proposes an index for quick screening of nitrogen fixation in Azotobacter.

Seasonal studies of the dinoflagellate Ceratium longipes (Bailey) Gran in the Bedford Basin, Canada

During an extensive bloom the subsurface Ceratium longipes (Bailey) Gran maximum layer was monitored with an attenuance meter and a particle counter in the Bedford Basin, Nova Scotia. This layer was controlled by the density-gradient. The cells absorbed mainly blue light in the region of 450–500 nm. Maximum cell number at the subsurface Ceratium maximum layer was 6.5 × 10 4 cells · 1 −1, and single cell volume 6 × 10 4 μm 3. Maximum total particle volume was 8.8 ppm and dominated by particles with diameters in the range 40–51 μm. The C. longipes made up 70% of total particle volume. A ratio by weight of organic carbon to nitrogen was 8, and the ratio of Ceratium carbon to chlorophyll a 84 ± 16. The growth rate was 0.56 doublings · day −1, which is ≈ 40% of the empirical maximum at 7°C. The maximum quantum yield φm was 0.05 mole C · Einstein −1. The effect of self-shading on φm was confirmed. The maximum light-saturated photosynthetic rate P m B , was 10.4 mg C · [mg Chl a] −1 · h −1 or 0.07 mg C · [mg plant C] −1 · h −1. The maximum index of dark respiration R d B was − 0.25 mg C· [mg Chl a] −1 · h −1 which corresponded to 2.5% of the P m B value. The physiological properties, i.e., φm, P m B and R d B of the dinoflagellate C. longipes are similar to diatoms even though their chemical properties are quite different.

Experimental and clinical studies on renal disturbance in obstructive jaundice.

Renal functions and the clinical courses of 14 patients with renal disturbances associated with obstructive jaundice were studied. All patients had high concentrations of serum bilirubin, long durations of jaundice and episodes of shock due to massive hemorrhage or severe inflammation. In an experimental study on jaundiced rats, effects of hypotension or bilateral renal artery occlusion on renal function and renal cortical mitochondrial respiration at 1 week, 3 or 6-weeks after biliary obstruction were investigated. In jaundiced rats, there was no remarkable difference in renal function, but the renal mitochondrial respiration indices decreased with prolongation of the biliary obstruction. In hypotensive rats with prolonged biliary obstruction, the mitochondrial function was impaired, and in the rats with renal artery occlusion, the mitochondrial impairment was more severe. Based on these clinical and experimental data, it is tentatively suggested that patients with prolonged jaundice should be considered in a prodromal state of renal failure and that any minute circulatory failure may induce acute renal failure.

Growth indices - Their rôle in understanding the growth, structure and distribution of Australian vegetation.

Growth indices, relating the relative growth of the photosynthetic canopy to light, temperature, moisture and soil nutrients, are described. Monthly values of these growth indices are multiplied, together with the foliage projective cover of the canopy, to give an estimate of the net photosynthetic index of the photosynthetic canopy.An exponentially-increasing respiration index adjusts for the loss of photosynthates by respiration in stems and roots, thus allowing for an estimate of a Current Annual Growth Index and a Total Growth Index, at maturity.A translocation index enables the partitioning of photosynthates between tops and roots to be estimated.These growth indices are examined in relation to the structure, growth and distribution of Australian woody vegetation.

Comparative Dental Material Cytotoxicity Measured by Depression of Rat Incisor Pulp Respiration

Equal amounts of Dycal, Cavitec, and N2 were mixed and exposed unset to phosphate-buffer-saline solution for 24 hours at 37 C. To aliquots of the three extracts, 1,4-'4C succinic acid and the pulp tissue of adult male Sprague-Dawley rats were added. Solutions were incubated at 38 C for 15 minutes. The '4CO2 produced by the tissue was measured, and an index of pulpal respiration was determined. Findings were comparable with histologic and cytotoxic cell culture studies that show N2 to be the most toxic. This new method of determining cytotoxicity is relatively simple, rapid, and easy to quantitate.

Effects of physical activity on initial level and response magnitude: An experimental study of the LIV

Two exercise and two relaxation conditions were used to manipulate subjects' overall level of physical activity. A digit-transformation-and-recall task was administered under each of these four conditions in order to elicit physiological responses. Measures of prestimulus level and response magnitude were taken for each of six dependent variables: skin conductance (SC), heart rate (HR), finger pulse volume (PV), and three respiration indices. It was hypothesized that as the subject's degree of activity increased the physiological variables would show ergotropic changes in prestimulus level together with decreasing magnitudes of response to the digit task. The results provided a reasonable degree of support for these predictions. Evidence for concomitant changes in prestimulus level and response magnitude was consistent with Wilder's Law of Initial Value (LIV). There were some cases, however, where response magnitude showed a predicted effect of treatment in the absence of a difference in prestimulus level; these findings could not be explained by the traditional LIV model.

Correlates of illness susceptibility.

Previous research has indicated that congitive-emotional factors, psychosocial stress, and systemic activity play a role in the contraction and course of numerous diseases. The present study investigated the relative contributions of these variables. Fifty-five male undergraduates were given questionnaires assessing general emotionality, and psychosocial stress and illness history over a four-year period. Autonomic indices of pulse rate, respiration, peripheral circulation, and skin resistance were also obtained under conditions of rest and stress (threat of electric shock). Using number of past illnesses as the dependent variable, a stepwise multiple regression analysis was performed. Only amount of psychosocial stress and, related to it, number of different kinds of psychosocial stress yielded significant partial correlations. Results are discussed in relation to other research, with emphasis on the conceptual and methodological difficulties of assessing psychophysiological mediators of morbidity.

External respiration and functional state of the respiratory center in hypoxia developing after inactivation of carbonic anhydrase

In experiments on cats, inactivation of carbonic anhydrase by acetazolamide (Diamox) prevented the development of hypocapnia and associated disturbances of the firing pattern of respiratory neurons in acute hypoxia. However, comparison of the electrophysiological data, the indices of external respiration and the acid—base balance, and pO2 and pCO2 of arterial blood showed that, while preventing the development of pathological respiration of Cheyne—Stokes type during hypoxia, inactivation of carbonic anhydrase by Diamox causes dissociation of thoracic and abdominal respiration and dyspnea. Changes in metabolic processes and disturbance of electrolyte balance at the cellular level also contribute to the development of dyspnea.

The possibility of prolonged survival of animals with an autotransplanted lung after removal of the intact contralateral lung

We conducted a functional and morphologic examination of dogs that survived after pulmonary autotransplantation and removal of the contralateral lung. Left lung autotransplantation was performed in 260 dogs, and 3 animals were subjected to excision of the contralateral intact lung in the late postoperative period. In the late follow-up period, the respiratory function of the autograft became normal, but the compensatory reserves were somewhat reduced. The animals easily tolerated the exclusion of the intact lung from respiration for 10 minutes, with no signs of respiratory insufficiency. In the early period after removal of the intact lung, hyperventilation and gas exchange disorders developed in the autograft, resulting in arterial hypoxemia and metabolic acidosis. The changes disappeared by the fifteenth postoperative day. The general state of the animals improved, as well. In both the early and late postoperative periods (maximum follow-up 3¼ years), the autotransplanted left lung supported a normal level of ventilation and gas exchange. The efficiency of gas exchange was evidenced by the normal parameters of arterial and venous oxygen saturation and acid-base balance. Histologic examination demonstrated a compensatory hypertrophy in the autograft that was a reaction to the removal of the right (intact) lung. The autograft ensured normal vital functions of the body after the removal of the intact lung, demonstrating satisfactory indices of external respiration, blood gases, and acid-base balance. Its performance served as a convincing proof of the restoration of the function and structure of the organ.

Attention Training Through Breathing Control To Modify Hyperactivity

The use of a psychophysiological method for training children in the control of hyperactive behavior is explored. The method involved attention training through breathing control, incorporating biofeedback and operant conditioning principles to help the child develop self-control over excessive and distracting motor behaviors and to maintain attention in learning situations. Six children (age 6-8 years old), from a private school for children with learning disabilities, participated in the study, three assigned to a group given the breathing control and attention training and three assigned to a control group. Measures obtained before, during, and after training included respiration indices, attention and vigilance test performance scores, and teacher ratings of classroom behaviors. The findings supported the feasibility of the training approach and provided important information relevant for future refinements in training and evaluation procedures.

Hemodynamic and ultrastructural evaluation of experimental myocardial infarctectomy

Infarcts were created in 16 pigs by ligating main branches of the left anterior descending coronary artery (LAD). Two animals died immediately; 14, in shock, were supported for 1 hour by intra-aortic balloon counterpulsation (IABCP). Infarctectomy was performed. Aortic flow and left ventricular pressure were improved by this procedure (8/14). Some animals (6/14) survived until they were put to death to obtain samples of the myocardium. Analysis of oxidative metabolism of mitochondria in the infarcted, marginal, and normal myocardium was carried out by measuring respiratory control index (RCI), adenosine diphosphate added/oxygen consumed (ADP/O), and rate of respiration (QO 2 ) indices. Electron microscopic studies were made in the same samples. Mitochondria exhibited marked depression in oxidative metabolism, not only in the infarcted area but also in the marginal portion. This finding suggests that the damaged area is larger than the frankly infarcted, cyanotic wall.

Physiological human reactions to acceleration along the vertebrosternal axis

An inquiry was made into the chief indices of external respiration in man during the action of accelerations (up to 15 g) directed along the dorso-thoracic axis at an angle of 65o to the back of the arrnchair. A definite regularity was established in the changes of the indices studied with various accelerations. Definite stages were noted in the development of individual reactions; this regularity reflected the essence of the general biological laws concerring body adaptation to new environmental conditions.

The central and peripheral action of chlorpromazine

Cardiovascular and respiratory disturbances occuring in chlorpromazine administration are more pronounced in decerebrated animals than in the intact ones. Antagonistic relationships of chlorpromazine and adrenaline (according to the indices of arterial pressure and respiration) developed in decerebrated animals without significant differences from the animals with an intact central nervous system.

Dehydrogenase activity in soils.

The reduction of 2,3,5-triphenyltetrazolium chloride to triphenylformazan has been used to estimate the dehydrogenase activity of the soil microflora in situ. Preliminary investigations suggest that the formation of the formazan may be used as an index of endogenous respiration in soil since a significant correlation has been obtained between dehydrogenase activity and the oxygen uptake of a number of different untreated soils. A direct relationship also was observed between formazan formation and the respiration of a soil sampled at intervals after the application of fresh plant material. In a survey of a number of field soils no relationship was found between dehydrogenase activity and bacterial numbers; however, the two parameters were parallel during the decomposition of flax residues added to one of the soils.

Measurement of the Respiratory Quotient of Plant Tissues in a Constant Gaseous Environment

In the course of plant physiological investigations it is often necessary to determine the respiratory activity of living tissues. The rate of carbon dioxide evolution has been used frequently as an index of respiration since it is relatively easy to measure. Under some conditions, however, the carbon dioxide released does not reflect certain biochemical changes associated with respiration which may be more closely correlated with oxygen absorption. If both gases are measured simultaneously, and the respiratory quotient (CO2/O2) calculated, a better interpretation of attendant phenomena may be given than if an analysis is made of only one gaseous component of the system. For example, erroneous conclusions may be drawn concerning the influence of low oxygen tensions, and the effects of various absorbed salts on the formation of organic acids in excised barley roots when C02 measurements alone are used as a basis for measuring the respiratory processes. Many methods for determining the respiratory quotients of living tissues have been proposed according to which samples of gas were withdrawn from an enclosed chamber and then subsequently analyzed for carbon dioxide and oxygen. Objections to these methods were based on changes in composition of the gaseous environment during the experimental period and in the necessity of great accuracy in the analytical estimations. Major improvements were developed by Fernandez (2), who provided a closed system with a Bunsen valve pump for circulating the gases through alkali towers to absorb the carbon dioxide, and an oxygen generator controlled by an operator to replace electrolytically an oxygen deficit indicated by a manometer. His apparatus was adopted in a slightly modified manner by Wetzel (7) and more recently in revised form by Bennet-Clark (1). The latter investigator introduced a non-pulsating pump and the automatic addition of