Aerial and Aquatic Respiration in the River CrabPotamonautes WarreniCalman with Notes on Gill Structure

Renal tubular acidosis in childhood

The most recent data for the carbon dioxide concentration, alkalinity and partial pressure of carbon dioxide in ocean water are reviewed. The total carbon dioxide content in the oceans is estimated to be 1.39×1020 grams CO2, about 53 times the total atmospheric carbon dioxide content. The oceans contain a greater quantity of CO2 than the amount expected if the oceans were a single homogeneous body of water. This indicates that their capacity is governed by the dynamic processes in the ocean such as the circulation and mixing of ocean water, vertical transpot of carbon by biological processes, and air‐sea CO2 gas exchange. Thus, dynamic models for the carbon cycle in the atmosphere‐ocean system are needed to evaluate the response of the oceanic and atmospheric carbon dioxide reservoirs to the industrial carbon dioxide input and climatic changes. A vertical one‐dimensional and box‐diffusion model, which has been developed by Oeschger et al22, has been used widely and successfully to describe the global carbon cycle. A modified version of their model, in which the size of the land biomass is assumed constant, is presented and used to evaluate the effects of climatic changes on the atmospheric and oceanic reservoirs. It appears that the predicted climatic warming resulting from the industrial carbon dioxide release would cause an increase in the airborne fraction of the industrial carbon dioxide and further accelerate a build‐up of industrial carbon dioxide in the atmosphere. Development of more sophisticated models, which include the ocean circulations, regional differences in the oceans, and climate feedback, is strongly urged for quantitative assessment of the industrial carbon dioxide effects on the climate and the oceanic carbon dioxide reservoir.

Dr. Comroe once stated (in conversation) that while it may sometimes be difficult to prove the value of oxygen therapy, there is ample evidence of its hazards. This is particularly true in premature infants. Should oxygen, therefore, be used at all in the premature nursery? If so, for what infants? And how can they be protected from its misuse? 1. Progressive hypoxemia leads to anoxia in most severe or fatal disease in newborn and premature infants. Circumstances associated with anoxia are often followed by brain damage. Therefore, a severely reduced blood oxygen saturation or tension in a sick premature or term newborn should be raised if this can be done safely. 2. Thus, additional oxygen should be used for those infants whose arterial blood (when they breathe air) is carrying significantly less oxygen, than that to be expected of normal infants in air. 3. Oxygen is misused if it increases blood oxygen much above that normal in air-breathing. Such misuse is not only wasteful. It may cause retrolental fibroplasia. Impaired vision from this cause is still being seen, and we cannot yet be positive that excess oxygen causes no other pathologic changes in prematures besides those in the retina. The problem of misuse may be better stated in terms of oxygen tension (or pressure —hence pO2) than of oxygen percentage or concentration. As 21% of the atmosphere, oxygen has a partial pressure of 160 mm Hg in air at sea level and pO2 in the pulmonary alveoli of normal term and premature infants is (like that of adults about 105 mm Hg.2 In the arterial blood of such infants pO2 is usually within or near a range of 70-80 mm Hg, so that a normal gradient or pressure loss of 25-35 mm Hg occurs between alveolus and capillary.

A significant discrepancy was noted in our laboratory between the total plasma carbon dioxide concentration measured by the Kodak Ektachem 700 and the bicarbonate concentration derived from the Corning 170 pH/Blood Gas analyser in an 8-day-old patient. The concentration of total carbon dioxide was 18 mmol/L while the derived bicarbonate was 13 mmol/L. The patient was eventually diagnosed as maple syrup urine disease. This finding led us to examine the effect of various organic acids on the measurement of carbon dioxide by the Ektachem 700. Several interfered significantly. Clinicians should be aware that when organic acid concentrations are increased, the Ektachem 700 total carbon dioxide result may be falsely raised.

Six cores were obtained along a 70‐km transect perpendicular to the Peru coast in the highly productive upwelling region near 15°S, at depths ranging from 90 to 5,300 m. All of the sediments sampled were diatomaceous oozes. Three cores overlain by poorly oxygenated water had Thioploca‐like filamentous bacteria in surface sediments. Total organic carbon and total nitrogen contents of the sediments ranged from 0.8 to 10% and from 0.1 to 1% (dry wt). For the 90‐m and 268‐m cores, which had 210Pb surface sediment accumulation rates of about 0.6 and 1.1 cm · yr‒1, surface sediment organic carbon accumulation rates were 40 and 70 g C·m‒2·yr‒1. The organic carbon and total nitrogen distributions in the three cores from the oxygen minimum zone indicate that there have been variations in the rate of accumulation of organic matter over time. These variations may be related in part to the frequency and intensity of El Niño events.Porewater ammonium, nitrate, nitrite, total carbon dioxide, sulfate, and sulfide concentrations were measured. Remineralization rates in sediments calculated from the dissolved carbon dioxide profiles range from 0.6 to 20 g C·m‒2·yr‒1. Total carbon dioxide concentrations in porewaters of two oxygen‐minimum‐zone sediments were modeled using both steady state and nonsteady state distributions of metabolizable organic matter.

BACKGROUND: Modeling toxic pulmonary edema for the purpose of studying the effectiveness of drugs is associated with difficulties in model validation and objectification of drug effectiveness criteria. To confirm the significance of changes in pulmonary coefficients and visual changes in lung tissue, acid-base balance and blood gas analysis are often used to objectify emerging gas exchange disorders. AIM: To investigate the acid-base composition and blood gases in mice during the progression of toxic pulmonary edema caused by inhalational phosgene exposure. MATERIAL AND METHODS: Toxic pulmonary edema was induced by exposing mice to phosgene at a dose corresponding to LCt50 in an inhalation chamber. Blood samples were analyzed for acid-base balance and gas parameters, including partial oxygen pressure (pO2), partial carbon dioxide pressure (pCO2), total hemoglobin (tHb), oxyhemoglobin (O2Hb), carboxyhemoglobin (COHb), methemoglobin (MetHb), reduced hemoglobin (RHb), oxygen saturation (sO2), oxygen concentration (O2ct), oxygen capacity (O2cap), partial oxygen pressure at 50 % saturation (P50), total carbon dioxide (tCO2), true and standard bicarbonate (HCO3–, SBC), actual and standard base excess (BEb, BEecf), anion gap, lactate, and concentrations of sodium, potassium, chloride, and ionized calcium. Measurements were performed using a gas analyzer at 30 minutes, 3 hours, and 24 hours after exposure initiation. RESULTS: Significant shifts in blood gas composition and acid-base balance were observed 3 hours after pulmonary edema initiation. These included decreased acid-base balance, reduced oxyhemoglobin levels, lowered oxygen saturation, and elevated partial carbon dioxide pressure, indicating respiratory insufficiency and compensated respiratory acidosis. Major changes in acid-base parameters were observed after 24 hours, with normalization of pH accompanied by increases in true and standard bicarbonate levels, as well as total carbon dioxide content. Changes in actual and standard base excess were observed, reflecting a reduction in base deficit. Electrolyte levels remained unchanged in all experimental groups throughout all observation periods. CONCLUSIONS: The study elucidated the progression of respiratory hypoxia during toxic pulmonary edema and confirmed that respiratory hypoxia serves as a key pathogenic link, leading to significant disruptions in energy metabolism during the progression of pulmonary edema.

Toadfish (Opsanus tau) essentially lacking circulating erythrocytes were pre pared by repeated exchange transfusion with serum. The rate of nitrogen secretion is not changed by removal of the erythrocytes. Oxygen secretion is slowed dras tically. This shows that nitrogen secretion does not require erythrocytes and is not driven by oxygen secretion. In the absence of circulating erythrocytes, oxygen and nitrogen are brought into the swimbladder in proportion to their concentrations in blood plasma. Carbon dioxide partial pressure in the secreted gas mixture is three to fourfold greater than the pressure generated by acidifying arterial blood. This implies counter-current multiplication of the small increment of carbon dioxide pressure brought about by acidification of the blood. In the presence of blood buffers, increased carbon dioxide pressure will increase blood bicarbonate. Three independent estimates indicate that, during gas secretion, gas gland blood is near pH 6.5. Total carbon dioxide (CO2, HCO3, CO3) is increased from the arterial value near 2 mM to about 14 mM, divided nearly equally between carbon dioxide and bicarbonate anion. The increment in total blood carbon dioxide concentration together with the well-known increment in lactate anion may serve to salt out inert gases from solution in blood plasma.

The effects of acute exposure to 3 different temperature and humidity conditions on arterial blood-gas and acid-base balance in goats were investigated after intravenous bolus administration of xylazine at a dose of 0.1 mg/kg. Significant (P<0.05) changes in the variables occurred under all 3 environmental conditions. Decreases in pH, partial pressure of oxygen and oxyhaemoglobin saturation were observed, and the minimum values for oxygen tension and oxyhaemoglobin saturation were observed within 5 min of xylazine administration. The pH decreased to its minimum values between 5 and 15 min. Thereafter, the variables started to return towards baseline, but did not reach baseline values at the end of the 60 min observation period. Increases in the partial pressure of carbon dioxide, total carbon dioxide content, bicarbonate ion concentration, and the actual base excess were observed. The maximum increase in the carbon dioxide tension occurred within 5 min of xylazine administration. The increase in the actual base excess only became significant after 30 min in all 3 environments, and maximal increases were observed at 60 min. There were no significant differences between the variables in the 3 different environments. It was concluded that intravenous xylazine administration in goats resulted in significant changes in arterial blood-gas and acid-base balance that were associated with hypoxaemia and respiratory acidosis, followed by metabolic alkalosis that continued for the duration of the observation period. Acute exposure to different environmental temperature and humidity conditions after xylazine administration did not influence the changes in arterial blood-gas and acid-base balance.

The H+ mobilization model has been recently reported to accurately describe intradialytic kinetics of plasma bicarbonate concentration; however, the ability of this model to predict changing bicarbonate kinetics after altering the hemodialysis treatment prescription is unclear. We considered the H+ mobilization model as a pseudo-one-compartment model and showed theoretically that it can be used to determine the acid generation (or production) rate for hemodialysis patients at steady state. It was then demonstrated how changes in predialytic, intradialytic, and immediate postdialytic plasma bicarbonate (or total carbon dioxide) concentrations can be calculated after altering the hemodialysis treatment prescription. Example calculations showed that the H+ mobilization model when considered as a pseudo-one-compartment model predicted increases or decreases in plasma total carbon dioxide concentrations throughout the entire treatment when the dialysate bicarbonate concentration is increased or decreased, respectively, during conventional thrice weekly hemodialysis treatments. It was further shown that this model allowed prediction of the change in plasma total carbon dioxide concentration after transfer of patients from conventional thrice weekly to daily hemodialysis using both bicarbonate and lactate as dialysate buffer bases. The H+ mobilization model can predict changes in plasma bicarbonate or total carbon dioxide concentration during hemodialysis after altering the hemodialysis treatment prescription.

The isolation and characterization of the hemoglobin ofBrachyplatystoma sp.: A tropical catfish

Tulip bulbs (Tulipa spp.) were placed under ventilated low pressure storage (LPS) conditions for 14 days in either August or September. Compared to 760 mm Hg stored bulbs, LPS suppressed leaf growth and floral development. These effects were highly visible after storage in air at either 76 or 150 mm Hg and in the month of August. When tulip bulbs were forced, LPS treatments applied in August delayed flowering of most cultivars and flower size was occasionally reduced; in September treatments, LPS ventilation with additional O2 and CO2 accelerated flowering of 2 cultivars, but flower size was reduced. When stored under 76 mm Hg in air in August, most cultivars of hyacinth (Hyacinthus spp.) were subsequently delayed in flowering, but daffodils (Narcissus spp.) were not. Except for one cultivar of each species, LPS did not affect the percent of plants flowering, plant height or flower size. Penicillium growth on the bulb tunics was enhanced by humidifying the air under LPS conditions. It is concluded that LPS provides no advantages over the ventilated, temperature controlled units presently employed.

Hemolymph oxyhemocyanin, protein levels, acid-base balance, and ammonia and urea excretions of Penaeus japonicus exposed to saponin at different salinity levels

Are locally adapted goats able to recover homeothermy, acid-base and electrolyte equilibrium in a semi-arid region?

Blood pH, carbon dioxide and oxygen partial pressures, bicarbonate, total carbon dioxide, base excess, standard bicarbonate and oxygen saturation concentrations were measured by blood gas analyses in a study of assessment of the acid-base status in young calves. Venous blood samples were taken from 80 healthy female Holstein calves, from four to 30 days of age. The calves were divided in two groups based on the interval between the morning milk feeding and the blood sample collection (up to 30 minutes or over two hours). Greater alkali reserve and higher carbon dioxide pressure values were observed later than 2h after milk feeding, supporting the influence of the diet on the acid-base balance of calves during the milk feeding phase.

Quantitative studies of ventilation during inhalation of carbon dioxide in normal and emphysematous patients