Free Carbon Dioxide Research Articles

Substrate exchange in human limb muscle during exercise at reduced blood flow.

The substrate exchange of the calf muscles during leg exercise was compared in patients with chronically reduced blood flow and in matched controls. The arteriovenous differences of glucose, lactate, pyruvate, free fatty acids, glycerol, acetoacetate, beta-OH-butyrate, oxygen, and carbon dioxide were analyzed at rest, at the end of two exercise periods at various work loads, and after 10 min of recovery. Calf blood flow was measured with an electrocardiogram-triggered, computerized, strain gauge, venous occlusion plethysmograph. The results indicate that there was increased extraction of oxygen and ketone bodies in patients with reduced blood flow during exercise, whereas the glucose extraction tended to be lower than in controls. The leg respiratory quotient was lower in the patients even at the point of claudicating pain, suggesting oxidation of endogenous fat. The simultaneously elevated lactate release can be explained by local hypoxia in some muscle fiber populations. The findings are discussed in relation to the enzymatic adaptations known to occur in the calf muscle tissue of these patients.

Neuronal man. The biology of mind By Jean-Pierre Changeux (translated by Dr Laurence Garey). New York: Pantheon Books, 1985

Clinical, metabolic, and pathologic studies of a patient with advanced morbus caeruleus (tetralogy of Fallot) are reported. The patient died at the age of 19, and had been cyanosed since the age of 2. He was proficient scholastically, and, until a year before death, suffered a minimum of handicap from his malady. He was thought to have had rheumatic fever at the age of 9 and subacute bacterial endocarditis during his last year of life. A colon bacillus abscess of the cerebrum was immediately responsible for death.The metabolic investigations revealed a profound variation from the normal in the acid-base equilibrium of the body, and changes in renal function. As much as 75 per cent of the blood in the cardiac chambers was thought to traverse a right-to-left shunt. The oxygen saturation of the arterial blood varied between 62 and 58 per cent. These are critical levels for human existence. The oxygen capacity was about 35 volumes per cent. The carbon dioxide content of the arterial blood was less than 33 volumes per cent. The arterial pHs was less than 7.29. A profound, uncompensated acidosis was attributed to the increased concentration of undetermined acids and failure of the respiratory center to maintain the usual balance between free and combined carbon dioxide. The functional insufficiency of the kidneys was attributed to anoxemia, venous congestion, and acidosis.

Determination of total carbon dioxide in seawater by capillary type isotachophoresis

A new analytical procedure for total carbon dioxide in seawater was developed: a capillary-type isotachophoresis which applied a tubular microporous PTFE membrane as a preliminary enrichment was used. Carbon dioxide was generated by adding sulfuric acid to seawater samples, permeated through a tubular microporous PTFE membrane and dissolved in sodium hydroxide solution for the separation from large amounts of coexisting anions, such as chloride and sulfate ions. A linear working curve was obtained for artificial seawater samples containing up to 40 mg/l of total carbon dioxide. The proposed method was applied to the determination of total carbon dioxide in surface and bottom seawater samples. Concentrations of the total of free carbon dioxide and carbonic acid, hydrogencarbonate and carbonate ions in these samples were calculated from the concentration of total carbon dioxide, temperature, pH and salinity of samples measured in situ.

Kinetics of Ce(IV) oxidation of α‐keto acids in sulfuric‐perchloric acid media

AbstractThe rates of oxidation of four α‐keto acids, glyoxylic, pyruvic, phenylglyoxylic, and 2‐oxobutyric acids by Cerium(IV) in H2SO4HaHSO4 and H2SO4HClO4 solutions, have been studied spectrophotometrically. The rate data suggest that CeSO is the most reactive of the Cerium(IV)‐sulfate complexes present in the H2SO4NaHSO4 and H2SO4HClO4 systems. The oxidation reaction is proposed to be a one‐electron process with the rate‐determining step being the decomposition of a α‐ketoacid‐Cerium(IV) complex to a free radical and carbon dioxide through a transition state.

Influence of homogeneous condensation on the gasdynamics and radiation of a free carbon dioxide jet

The influence of homogeneous condensation on the gasdynamics and radiation of carbon dioxide gas during jet expansion into a vacuum is investigated experimentally and theoretically.

Comparison of central venous and arterial pH and PCO 2 during open-chest CPR in the canine model

Arterial blood gases are difficult to obtain during cardiopulmonary resuscitation (CPR) in human beings, and the possibility of venous sampling is raised frequently. The reliability of central venous gases as a substitute for arterial blood gases in assessing acid base status, however, has not been investigated adequately under conditions of CPR. Therefore, femoral arterial and central venous catheters were placed in 24 mongrel dogs, and ventricular fibrillation was electrically induced. After varying predetermined downtimes from five to 60 minutes, open-chest CPR was begun, and arterial and central venous blood gases were simultaneously drawn every five minutes during a 30-minute period. Arterial pH (pHa) was consistently higher than central venous pH (pHcv) by an average of .048 units. A significant correlation existed between the pHa and pHcv at all times during CPR, with an overall r = .9771 (P less than .0001). The difference between central venous PCO2 (PcvCO2) and arterial PCO2 (PaCO2) was 5.17 mm Hg prior to cardiac arrest, but it increased 300% to a mean of 15.51 mm Hg during CPR. Correction of pHcv using conventional methods to account for this respiratory component decreased the correlation between pHa and pHcv to r = .6905. The ability of pHcv to substitute for pHa was assessed, and showed a sensitivity of 100% when pHa of 7.2 was used as a criterion for treatment. In this model, pHcv is a sensitive indicator of pHa and it may be used to guide bicarbonate therapy. The increased PcvCO2 during CPR probably results from the marked tissue lactic acid production and subsequent shift of the bicarbonate buffer into free carbon dioxide.

Influence of Water Hyacinth Cover on the Physico‐chemical Characteristics of Water and Phytoplankton Composition in a Reservoir near Jaipur (India)

AbstractWater hyacinth (Eichhornia crassipes (Mart.) Solms.) invaded a eutrophic reservoir receiving domestic sewage near Jaipur (India) during 1975 and gradually developed a complete thick cover over the whole water body during Sept.–Oct. 1978. The physico‐chemical characteristics of the water and the phytoplankton composition were studied during Sept. 1977–Sept. 1979 by fortnightly sampling. The changes observed during the second year of study are ascribed to the water hyacinth cover. The important changes were: lowering of water temperature, pH, dissolved oxygen content and nitrate nitrogen, and increase in total alkalinity, free carbon dioxide, chemical oxygen demand, ammonia nitrogen, sulphides, calcium, magnesium and phosphate phosphorus. The changes in the phytoplankton were both qualitative and quantitative. The green algae, particularly the species of Ankistrodesmus, Chlorella, Crucigenia and Selenastrum, increased considerably and replaced the blue‐green algae, of which Oscillatoria and Microcystis disappeared totally. The densities of several other taxa changed significantly.

Comparison of seasonal and diurnal patterns of some physico‐chemical parameters of the open and closed parts of Loktak Lake, Manipur, India

A comparative study of the periodic and aperiodic variations of some physico‐chemical parameters of the open and closed parts of the Loktak Lake, Manipur, India, was carried out for a period of three years from 1976–78 to investigate the effects, if any, of human activities on these variations. The closed part of the lake, used for controlled fishing was well protected, whereas the open part was subjected to considerable human activities. The variation in the physico chemical parameters in the open lake were different from those of the closed lake in that (a) there was distinct seasonal variation in DO which was not evident in the closed lake and (b) there was direct relationship between diurnal variation of CO2 and pH instead of an indirect relationship in the closed lake. The variation in pH, electrical conductivity, bicarbonate, free carbon dioxide and chloride between 1976–78 had a similar pattern in the two parts of the lake.

Carbon limitation of biomass production in high‐rate oxidation ponds

Theoretical considerations confirmed by outdoor experiments indicated carbon limitation of biomass production in high-rate oxidation ponds at certain seasonal and operational conditions. Apparently, free carbon dioxide concentration in the pond is the major determinant of carbonlimiting algal photosynthesis. High concentrations of free CO(2) are provided through bacterial respiration which is the main contributor to algal photosynthesis. At high photosynthetic activities and low organic loadings, free CO(2) concentrations are low; its flux into algal cells determines photosynthesis and biomass production rate in the pond.

The use of carbonate equilibrium chemistry in quantifying algal carbon uptake kinetics

The method of utilizing the principles of carbonate equilibrium chemistry to monitor the rate of inorganic carbon uptake by a variety of algal species is presented and discussed. The usefulness of this technique is demonstrated for both batch and chemostat algal culture. Data obtained from carbon limited batch and chemostat cultures suggest that the specific growth rate of a variety of algal species may best be represented as a Monod response to the free carbon dioxide concentration. The monitoring of carbonate equilibrium in the batch method provides a simple, rapid and inexpensive technique for obtaining rates of algal carbon fixation. This technique is well suited for obtaining the large volumes of detailed kinetic data necessary in building a basis for understanding the factors involved in algal productivity and algae species shifts, in both controlled and natural aquatic ecosystems.

The physico-chemical hydrology of a tropical seasonal river-upper Ogun river

The physico-chemical properties of the Ogun River were recorded between January 1974 and December 1975. A wet season with mean monthly rainfall of 9.72 cm. (s.d. = 5.07 cm) occurred from April through October, while a dry season with mean monthly rainfall of 0.56 cm. (s.d. = 0.99 cm) occurred between November and March. The seasonal changes in the rainfall of the drainage area resulted in an alternation of the hydrological regimes of the river. The high water level of the river that arose as a result of the rains made the water flowed unidirectionally from July through December. After the rains, the water level receded gradually to a point where by January the river broke up into a chain of pools. In a lotic state, the water's tansparency, pH, total alkalinity and conductivity were lower, while its dissolved oxygen, free carbon dioxide concentrations were higher than the corresponding conditions in the residual pools formed when the water was lentic. In this latter form, the observed diurnal surface water temperature fluctuations were more and diel thermal stratification occurred. It was evident that the water in both phases was well aerated. The diurnal fluctuations in the water temperatures and the relationships between the determined environmental factors were assayed.

A control mechanism of the phytoplankton respiration in a eutrophic reservoir

In the eutrophic Bautzen reservoir (German Democratic Republic) the compensation light intensities (photosynthesis = respiration of the phytoplankton) have been found to be extremely low if no free carbon dioxide is available. This result is interpreted as a minimization of the cell respiration under CO2-limitation of the photosynthesis.

Possibility of using the hydrogeochemical indicator (pH) of subsurface waters in earthquake forecasting

Studies of variations in hydrogen-ion concentrations (pH) in the Near-Tashkent Basin before and after the Abaybazar and Tashkent earthquakes established that on the basis of a change in the pH of the waters of the basin and the nature of the constructed curves (of both Groups I and II), it is possible in conjunction with other indicators (pressure, temperature, and gas content of the waters), some 8 to 16 months beforehand, to forecast the beginning of an earthquake. In this case, a steady lowering of the pH from 8 to 7 was observed prior to the earthquake. The earthquake takes place with an increase in pH from 7 to 7.5 to 7.9. Changes in the pH of subsurface waters are supposedly associated with an increase in the amount of free carbon dioxide in the artesian water.

Temperature Effects on Assimilation and Respiration in the Fontinalis duriaei-Periphyton Association

Fontinalis duriaei Schimp. was collected from Coles Creek in Houghton Co., Michigan, to determine its assimilation and respiration under 5 temperature (1, 5, 10, 15, 20'C) and 3 light (2400, 5400, 10,800 lux) condi- tions, using a Gilson differential respirometer. At 5400 lux the Fontinalis dur- iaei-periphyton association exhibited peak assimilation at 10OC, where it ap- proached light saturation under the experimental conditions. Adaptation to cool climates and spring and fall growth maxima are implicated. Aquatic bryophytes have received little attention in most ecological studies. Aut- ecological studies of bryophytes are likewise less common than for the higher plants, and we find ourselves with little understanding of the functioning of these organisms when we consider using them for bioassay studies or including them in an ecosystem model. The role of aquatic mosses in providing a substrate for aquatic insects has been demonstrated (Glime & Clemons, 1972), and it seems appropriate that the eco- logical roles of this important primary producer should be understood. This study was designed to study the effects of temperature and light intensity on the assimilation and respiration of the Fontinalis duriaei-periphyton association. Fontinalis is probably one of the most widely studied of the aquatic bryophytes. As early as 1910 Blackman and Smith used Fontinalis antipyretica Hedw. for their well-known experiments illustrating carbon dioxide concentration as a limiting factor for photosynthesis. Its large size and availability permitted the use of Fontinalis as an experimental organism for basic studies on the photosynthetic process of an aquatic plant in the following studies: Harder (1921) provided further explanations on limiting effects of carbon dioxide and light on photosynthesis. Bode (1940) studied the effects of red, blue and white light on assimilation, respiration and pigments. Steemann-Nielsen (1947) illustrated its dependence on free carbon dioxide for photosynthesis, whereas other aquatic plants he worked with could use bicarbonates as well. Steemann-Nielsen and Kristiansen (1949) used Fontinalis to demonstrate the presence and activity of carbonic anhydrase in an aquatic plant which was unable to utilize bicarbonate. Schwoerbel and Tillmanns used F. antipyretica to show the ability of a moss to assimilate ammonium ions, causing a decrease in pH (1964), but demonstrated that light is required by this species to activate nitrate reductase for nitrate uptake (1974). Recently, Fontinalis has been suggested as a possible bioassay tool. Hanuska (1968) investigated methods for assessing the toxicity of waste materials on Fontinalis

The influence of thick floating vegetation (Water hyacinth: Eichhornia crassipes) on the physico — chemical environment of a fresh water wetland

Measurements made in fresh water wetland have shown that temperature, pH, dissolved oxygen and bicarbonate alkalinity in the hyacinth infested area were lower, but dissolved free carbon dioxide concentration was excitingly greater than in the open water area. This extreme hypoxic and hypercarbic condition of hyacinth covered areas was caused by the thick coverage of Eichhornia crassipes which was crucial for the composition of the characteristic flora and fauna.

Occurrence of a thermocline in two lakes of the semi-arid region in western Rajasthan, India

Fifteen-month water temperature data of vertical profile of the two lakes, Padamsagar and Ranisagar of the semi-arid region in Western Rajasthan are discussed. A remarkably wide variation of temperature from the surface to the bottom during the summer, particularly in the month of June (12°C at Padamsagar and 9.5°C at Ranisagar) resulted in a clear-cut thermocline which hindered distribution of dissolved oxygen, free carbon dioxide and nutrients from top to bottom. However, circulation existed during the isothermic period (the winter). This is the first record of the occurence of a Thermocline in any lake or impoundment in India and is supposed to be due to lack of mixing of water because of the lakes are sheltered from wind action by high rocks bounding their eastern and western banks, and to the low surface to depth ratio.

Carbon-uptake by the submerged hydrophyte Utricularia purpurea

Photosynthetic carbon-uptake and dark respiration by Utricularia purpurea Walt. were determined on five occassions in a laboratory chamber incubated at lake temperatures and a selected illuminance (10, 000 lux). The photosynthetic capacity declined during the autumn to less than 0.7% of the midsummer rate. This species does not use bicarbonate at the bicarbonate concentrations present in the soft waters of Mirror Lake (alkalinity 0.04–0.07 mequiv. 1 −1). Photosynthesis in chambers with natural levels of free carbon dioxide is carbon-limited in short-term assays, suggesting a practical difficulty of using chamber methods to measure hydrophyte productivity in soft-water ecosystems.

Acute effects of glucose-insulin-potassium infusion on myocardial substrates, coronary blood flow and oxygen consumption in man

To determine whether myocardial oxygen consumption (MVO 2) might be reduced when myocardial substrate uptake is changed from predominantly lipid to predominantly carbohydrate, measurements of arterialcoronary sinus glucose, lactate, free fatty acids, oxygen, carbon dioxide and coronary sinus blood flow (by thermodilution) were obtained in 13 fasting patients. Measurements were initially made in a basal control state and then repeated at 10, 20 and 30 minutes during an infusion of glucose-insulin-potassium. After 30 minutes of infusion, there was a three-fold increase in myocardial glucose uptake (44 ± 10 to 145 ± 19 +μmoles/min [mean ± standard error of the mean], P < 0.01), a two-fold increase in myocardial lactate uptake (35 ± 4 to 77 ± 10 μmoles/min, P < 0.001) and a 75 percent decrease in myocardial free fatty acid uptake (34 ± 5 to 9 ± 3 μmoles/min, P < 0.01). Cardiac respiratory quotient rose from 0.70 ± 0.05 to 0.93 ± 0.08 ( P < 0.001). Sum of oxygen extraction ratios for glucose and lactate rose from 51 ± 7 percent at control to 155 ± 22 percent at 30 minutes of infusion ( P < 0.001) and suggested that much of the enhanced myocardial carbohydrate uptake met a nonoxidative fate, such as glycogen formation. During glucose-insulin-potassium infusion, arterial-coronary sinus oxygen decreased by 13 percent, coronary sinus blood flow increased by 12 percent and MVO 2 was unchanged. The increase in coronary sinus blood flow was associated with a 13 percent decrease in coronary vascular resistance and a small, but significant, increase in serum osmolarity (289 ± 3 to 299 ± 3 mOsm/liter, P < 0.001). It is concluded that glucose-insulin-potassium infusion, while causing prompt alteration in myocardial substrate utilization from lipid to carbohydrate, produces no significant measurable change in myocardial oxygen consumption. However, such infusion is accompanied by a measurable increase in coronary sinus blood flow and a decrease in coronary vascular resistance.

Carbon: The real limit to growth

Under preindustrial conditions the quantities of animal and vegetable life on Earth were fixed by the rate at which animals and microorganisms could restore carbon to vegetation through atmospheric carbon dioxide. The combustion of fossil hydrocarbons has disturbed this balance by bringing “new” organically useable carbon into the ecosystem. The biomass and free carbon dioxide on the Earth has accordingly increased since the industrial revolution and will continue to increase until and beyond the cessation of hydrocarbon-based technology. The author presents arguments in support of this hypothesis and indicates in the Appendix how the carbon cycle and its response to disturbances might be treated mathematically.

Tidal cycling and parental behavior of the cichlid fish, Biotodoma cupido

Parental behavior of the substrate-brooding cichlid, Biotodoma cupido, was studied in a small creek entering the lower Essequibo River, Guyana, where the freshwaters are affected by semi-diurnal tides. Physico-chemical variables of the tidal cycle were associated with the parental behavior of B. cupido. During late ebb and early flood tides, while off-spring were nest dependent, parents displayed intense aggression toward brood predators, mainly characins. At low tide, when the concentration of dissolved oxygen decreased to about 4 mg 1−1 and that of free carbon dioxide increased to 28 mg 1−1, parents entered a state of somnolence and brood predators vanished. Early flood tide brought an immediate and dramatic reversal of hypoxic and hypercarbic conditions and an associated renewal of aggressive and predatory activity. At very low tide, parents orally transferred the brood to a secondary nest depression in deeper water. The significance of water-level fluctuation to the evolution of this behavior, as well as that of parent-brood itineracy and the related phenomena of oral incubation and movable nests, is discussed.