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The metabolism of exogenous citrate by freshly collected human platelets has been investigated by measuring the disappearance of citrate from platelet suspensions and by measuring the formation of CO2 and glycogen from purified radioactive citrate. These studies indicate that platelets do not have the capacity to metabolize exogenous citrate.

A micro-technique was developed to measure fatty acid oxidation in vitro and to investigate its possible derangement in alcoholic fatty liver disease. Percutaneous liver biopsy specimens were obtained from nine control subjects and 28 alcoholic patients with mild to severe fatty liver. Fresh tissue (10-15 mg) was incubated at 37 degrees C for 90 min in a sealed reaction flask containing 1.92 mmol/l [1-14C]palmitic acid (1-2 microCi) and 1% essentially fatty acid free albumin in Krebs-Henseleit buffer, pH 7.4. Radiolabelled CO2 and perchloric acid-soluble ketone bodies were isolated and counted. CO2 production was markedly reduced in alcoholic patients with mild and severe fatty liver compared with controls. This depression was reversed by the addition of malate to the reaction flask but not by carnitine or coenzyme A. Ketone body production was similar in controls and patients with mild and severe fatty liver. After the incubation in vitro, the tissue was extracted with chloroform/methanol and the triglyceride fraction isolated by thin layer chromatography and counted for radioactivity. The rate of palmitic acid incorporation into triglyceride was higher in alcoholic patients, particularly those with severe fatty infiltration, compared with controls. It is suggested that alcoholic fatty liver is accompanied by a progressive reduction in palmitic acid oxidation with the major defect occurring in the tricarboxylic acid cycle. In contrast, the rate of palmitic acid esterification into triglyceride is enhanced.

When exposed to hypoxia, intact mice, with elevated blood ketones, live longer than mice with normal blood ketones. To evaluate a possible mechanism responsible for this phenomenon a rat brain slice preparation was used to determine if brain tissue would utilize glucose or ketones preferentially during exposure to reduced oxygen. Reducing available oxygen in the incubation medium from 95%, in steps, to 5% produced the expected gradual reduction in the carbon dioxide formation from glucose. In contrast, reducing the oxygen level to 40 and 20% resulted in a statistically significant stimulation of the production of carbon dioxide from the ketone beta-hydroxybutyrate. At very low oxygen levels carbon dioxide production from either substrate was reduced. These results are consistent with the hypothesis that ketones can be used in addition to glucose as a substrate for brain energy production even during reduced oxygen availability. If the increase in carbon dioxide production from ketones can be equated with an increase in energy production from this supplemental substrate then ketones may be therapeutically useful in avoiding the collapse of brain function during moderate hypoxia.

The fermentation of cellulose and cellobiose by Clostridium thermocellum monocultures and C. thermocellum/Methanobacterium thermoautotrophicum cocultures was studied. All cultures were grown under anaerobic conditions in batch culture at 60 degrees C. When grown on cellulose, the coculture exhibited a shorter lag before initiation and growth and celluloysis than did the monoculture. Cellulase activity appeared earlier in the coculture than in the monoculture; however, after growth had ceased, cellulase activity was greater in the monoculture. Monocultures produced primarily ethanol, acetic acid, H2 and CO2. Cocultures produced more H2 and acetic acid and less ethanol than did the monoculture. In the coculture, conversion of H2 to methane was usually complete, and most of the methane produced was derived from CO2 reduction rather than from acetate conversion. Agents of fermentation stoppage were found to be low pH and high concentrations of ethanol in the monoculture and low pH in the coculture. Fermentation of cellobiose was more rapid than that of cellulose. In cellobiose medium, the methanogen caused only slight changes in the fermentation balance of the Clostridium, and free H2 was produced.

The influence of pooled serum from either obese or normal weight males on glucose metabolism in human leucocytes has been studied. Leucocytes from normal weight males were incubated with 10-90% pooled serum and either [U-14C], or [1-14C]glucose. Compared to serum from the normal weight males, serum from the obese group had a more stimulating effect on the 14CO2 and [14C]lactate production from [U-14C]glucose and on the 14CO2 production from [1-14C]glucose. The two serum pools had the same stimulating effect on the Embden-Meyerhof pathway as indicated by the formation of [14C]lactate from [1-14C]glucose. Calculations revealed that the activity in the pentose phosphate pathway was stimulated more by serum from obese, than from normal weight males. It is a possibility that increased stimulation of the pentose phosphate pathway may contribute to the development of overweight.

Nocardia sp. which was isolated from soil is capable of degrading synthetic lignin and utilizing its monomer derivatives. Decomposition was monitored by measuring the 14CO2 evolved and O2 consumed, when the bacterium was grown on a medium containing specifically 14C-labeled ligning or monomer phenolic compounds as major carbon source. The time course of the 14CO2 release and O2 uptake indicates a significant depolymerization and utilization of lignin by the Nocardia sp.

Glucose turnover, as measured by CO2 production, lactate accumulation and carbon incorporation from [U-14C]glucose as sole energy substrate, was low on the 2nd day of culture of human embryos resulting from in-vitro fertilization but above that of unfertilized oocytes. In general, all parameters of metabolism increased substantially during the following 2 days of development but the rate of increase in lactate production was greater than that of CO2, especially between Days 3 and 4. Within developing embryos, no correlation was evident between the metabolic turnover of glucose and the method of patient stimulation, the morphological quality of embryos or the apparent rate of cleavage in culture. The results indicate that, before Day 3 of development, glucose is not effective as an energy source for the human embryo because of a blockade to glycolysis similar to that in mouse embryos.

Study of the effects of 19-hydroxy E prostaglandins on the metabolism of washed ejaculated human spermatozoa showed that these compounds depress the respiration of the spermatozoa, but do not affect the production of lactate. This effect is not seen with the prostaglandins of the E and F series.

Pseudomonas putida LP, which grows on lipoate, NH4NO3 and mineral salts, converts most of the organic substrate to bisnor-lipoate (1,2-dithiolane-3-propanoic acid) and acetyl-CoA. D-, L-, or DL-lipoate serve equally well as carbon and sulphur sources. There was no growth on or bacterial oxidation of the chemically synthesized bisnor- or tetranor-(1,2-dithiolane-3-carboxylic acid) chain-shortened analogues, but these, as well as lipoate, could supply the sulphur needed for growth when acetate was provided as the sole source of carbon. The uptake of lipoate by the bacterium is very slow and non-inducible, while the uptake of acetate is faster than octanoate. The oxidation of octanoate is more rapid and extensive than that of lipoate. Levels of acyl-CoA synthetase are not affected by the source of carbon, but activities of isocitrate lyase and malate synthase are higher when the cells are grown in acetate, octanoate or lipoate and lower when glucose is the carbon source. The glyoxylate cycle is induced to facilitate utilization of acetyl-CoA derived from lipoate, which is also degraded to water-soluble catabolites that yield the much smaller amount of sulphur required for growth.

In vivo and in vitro experiments have demonstrated that the myelographic agent metrizamide decreases neural tissue glucose metabolism whereas iohexol and iopamidol do not. This study compares the changes in slices of rat hippocampus CO2 production caused by the nonionic dimers iotrol and iodixanol with the effects of metrizamide and 2-deoxy-D-glucose. After 6-hr incubations, 70-mmol/l concentrations of iotrol and iodixanol increased CO2 production by 11 +/- 20% and 31 +/- 35%, respectively, as compared with the artificial CSF control medium. Metrizamide at 70 mmol/l and 2-deoxy-D-glucose at 35 mmol/l decreased CO2 production by 32 +/- 13% and 96 +/- 1%, respectively. The increases in CO2 production with iotrol and iodixanol appear to indicate that these molecules have some effect on cell metabolism. The mechanism for the increase in CO2 production could involve an effect on the glucose metabolic pathway or could be indirect via a mechanism that increases cell energy utilization. These in vitro effects have not been verified with in vivo experiments.

The experiments were confined to the effects of the addition of different sources of carbon (glucose, wheat straw, and sawdust) on the microbial activities in soils: loamy sand, loam and saline clay were used. The parameters used for this purpose were total bacterial counts, dehydrogenase test, CO2 evolution, and oxidation of organic carbon. Salinity of soils had deleterious effects on all the parameters used. Addition of organic matter resulted in marked increases in bacterial counts, formazan production, and CO2 evolution. Glucose showed the most rapid effect and highest levels. Wheat straw yielded the highest results and sawdust always showed the least effect.

To further validate the doubly labeled water method for measurement of CO2 production and energy expenditure in humans, we compared it with near-continuous respiratory gas exchange in nine healthy young adult males. Subjects were housed in a respiratory chamber for 4 days. Each received 2H2(18)O at either a low (n = 6) or a moderate (n = 3) isotope dose. Low and moderate doses produced initial 2H enrichments of 5 and 10 X 10(-3) atom percent excess, respectively, and initial 18O enrichments of 2 and 2.5 X 10(-2) atom percent excess, respectively. Total body water was calculated from isotope dilution in saliva collected at 4 and 5 h after the dose. CO2 production was calculated by the two-point method using the isotopic enrichments of urines collected just before each subject entered and left the chamber. Isotope enrichments relative to predose samples were measured by isotope ratio mass spectrometry. At low isotope dose, doubly labeled water overestimated average daily energy expenditure by 8 +/- 9% (SD) (range -7 to 22%). At moderate dose the difference was reduced to +4 +/- 5% (range 0-9%). The isotope elimination curves for 2H and 18O from serial urines collected from one of the subjects showed expected diurnal variations but were otherwise quite smooth. The overestimate may be due to approximations in the corrections for isotope fractionation and isotope dilution. An alternative approach to the corrections is presented that reduces the overestimate to 1%.

The effects of the test chemicals pentachlorophenol (PCP) and HgCl2 on the bioactivity of microorganisms in three different soils were studied in low and high concentrations (2 and 20 ppm). Bioactivity was measured in long-term experiments (18 weeks) by a threefold application of chemicals to soils of varying moisture content. The selected tests were measurements of ATP, of heat output under aerobic and anaerobic conditions and after amendment with glucose, of soil respiration after the addition of glucose, and Fe(III) reduction. The suitability of each test depends on soil microorganisms, on environmental conditions, and on soil properties. The effects caused by the chemicals were as follows. For the low concentration, stimulation or inhibition were mostly repaired within the observation period. The high concentration mostly induced inhibitions which increased or decreased as a consequence of the repeated application of the chemicals. The effects of chemicals were strongly modified by the soil types: in a soil with high organic matter content, differences to the control were lower than in soils with lower organic matter content. These experiments also indicate that measurement of only one physiological parameter is not sufficient to characterize chemicals ecotoxicologically.

The stimulating effect of piracetam on the respiration and glycolysis was observed in rat brain cortex slices incubated under oxygen atmosphere. After preincubation of the slices under pure nitrogen atmosphere, piracetam infuenced also decarboxylation of the C1-glucose carbon, indicating stimulation of the pentose cysle. Any significant effect of piracetam on the lowered by anoxia incorporation of 14C from U-14C-glucose into macromolecular fractions was not observed. The results have supported a protective effect of piracetam against oxygen deficiency, caused mainly by stimulation of metabolic glucose pathways, connected with energy production in CNS.

Cultured adult cardiac myocytes oxidize fatty acids and lactate preferentially to glucose. In contrast to other results obtained with isolated cardiac myocytes the preference for fatty acids is not dependent on carnitine administration, suggesting that the cells of this preparation possess sufficient reserves of carnitine and an intact mechanism for fatty acid activation. It is demonstrated by the substrate oxidation rates that these quiescent cells are in a state of minimal metabolic demand, thus resembling the arrested myocardium.

The timing and kinetics of fatty acid synthesis are delineated for Bacillus thuringiensis spore germination and outgrowth by analyzing [U-14C]acetate and [2-3H]glycerol incorporation into chloroform-methanol-extractable and trichloroacetic acid-precipitable lipids. In addition to measurement of pulsed and continuous labeling of fatty acids, monitoring the incorporation of radioactive phenylalanine, thymidine, and uridine from the onset of germination through first cell division provides a profile of biochemical activities related to membrane differentiation and cellular development. Upon germination, ribonucleic acid synthesis is initiated, immediately followed by rapid and extensive fatty acid synthesis that in turn precedes protein, deoxyribonucleic acid and triglyceride synthesis. Significantly, formation of fatty acids from acetate exhibits further developmental periodicity in which a large transient increase in fatty acid synthetic activity coincides with the approach of cell division. Radiorespirometric analyses indicates only slight oxidative decarboxylation of acetate and corroborates the extreme involvement of acetate in specific fatty acid biosynthetic reactions throughout cellular modification. These findings graphically demonstrate an intimate association of fatty acid metabolism with commitment to spore outgrowth and subsequent cell division.

Replacement of unlabeled gamma-butyrobetaine with gamma-[2,3,4-2H6]butyrobetaine has a profound effect on the stoichiometry between decarboxylation of 2-oxoglutarate and hydroxylation in the reaction catalyzed by human gamma-butyrobetaine hydroxylase. The ratios between decarboxylation and hydroxylation are 1.16 with unlabeled and 7.48 with deuterated gamma-butyrobetaine as substrate. From these ratios an internal isotope effect of 41 has been calculated. DV in the overall reaction measured as 2- oxoglutarate decarboxylation is 2.5 and DV/K is 1.0. For gamma-butyrobetaine hydroxylase from Pseudomonas sp. AK 1, 2-oxoglutarate decarboxylation exceeds hydroxylation with 10% when deuterated gamma-butyrobetaine is used. No excess was found with unlabeled substrate and no internal isotope effect could be calculated. DV for the bacterial enzyme is 6.

The metabolism of cardiac lipids and glycogen in hypoxic and well-oxygenated perfused rat hearts was studied in the presence or absence of epinephrine. Heart lipids were pre-labeled in vivo with [1-14C]palmitate. Triglyceride disappearance (measured chemically and radiochemically) was observed in well-oxygenated hearts and was stimulated by epinephrine (4.1 X 10(-7)M). Utilization of tissue triglycerides was inhibited in hypoxic hearts in the presence or absence of added epinephrine. Hypoxia resulted in a small increase in tissue 14C-free fatty acids and inhibition of 14C-labeled triglyceride fatty acid oxidation. Epinephrine had no stimulatory effect on fatty acid oxidation in hypoxic hearts. Utilization of 14C-labeled phospholipids (and total phospholipids) was similar in well-oxygenated and hypoxic hearts with or without added epinephrine. These results suggested that the antilipolytic effects of hypoxia were predominant over the lipolytic effects of epinephrine. Glycogenolysis was stimulated threefold by epinephrine in well-oxygenated hearts. Hypoxia alone was a potent stimulus to glycogenolysis. Addition of epinephrine to perfusates of hypoxic hearts resulted in a slight enhancement of glycogenolysis.

14C Tripalmitin was administered intraperitoneally to control mice and to mice bearing subcutaneous Krebs-2 carcinoma. The rate of excretion of 14CO2 was studied. The presence of a tumor induced a greater than 80% suppression of the formation of 14CO2 within 24 hours from the implantation of the tumor, thus allowing unambiguous identification of the tumor-bearing mice. When cancer patients were studied, along with normal volunteers and patients with non-neoplastic diseases, 14CO2 excretion data could be used to identify the cancer patients with an overall accuracy of 84%.

Important CO2 unloading occurs during hemodialysis (HD) when acetate-buffered dialysate is used. This is accompanied by alveolar hypoventilation. To gain more insight into the mechanisms of this alveolar hypoventilation, breathing patterns were studied in 5 patients with end-stage renal failure during HD using acetate-buffered dialysate, which induces CO2 unloading, or bicarbonate without CO2 loss. Ventilation was continuously measured with calibrated respiratory inductance plethysmography using techniques of multiple linear regression analysis. At regular intervals, arterial blood gas was sampled and expired air was analyzed. Breathing patterns were analyzed for VE, VT, TI, TE, and VT/TI. All data were compared with the respective starting value and with the respective value in the other setup. A greater decrease in ventilation was seen during HD with an acetate-containing dialysate because of irregular breathing patterns that resulted in a prolongation of expiratory time. Important variations in tidal volumes, striking apnea periods, and occasional periodic breathing were observed. We suggest that these irregularities are due to CO2 unloading leading to the point where ventilation is totally mediated through the output of the peripheral chemoreceptors.

Recent studies employing Pco2 microelectrodes demonstrated CO2 tensions in the renal cortex (60-65 mmHg) that are significantly greater than systemic arterial Pco2. Three sources for CO2 generation have been proposed: 1) luminal production from H+ and HCO-3,2) addition of HCO-3 to peritubular plasma with disequilibrium for H+/HCO-3/CO2, and 3) metabolic CO2 production. None of these mechanisms alone can adequately explain the findings. The purpose of this study was to examine mechanisms of elevated renal cortical Pco2 generation and maintenance by developing a mathematical model for the reaction and transport processes involved in proximal tubule HCO-3 reabsorption. Steady-state calculations of pH, Pco2, and [HCO-3] for luminal, cellular, and vascular compartments employing simple mass balance considerations are presented. Besides exploring the role of metabolic CO2 production in the genesis and maintenance of elevated renal cortical Pco2, we also propose and examine the additional mechanism of diffusive transfer of CO2 between renal cortical venular and afferent arteriolar capillaries. Our results show that the required magnitude of either metabolic CO2 production or diffusive CO2 transfer alone is large (3 mmol/liter RBF). However, vascular-vascular exchange of CO2 gas in combination with accepted levels of metabolic CO2 production can adequately explain the findings of an elevated renal cortical Pco2 of approximately 65 mmHg as measured experimentally in vivo.

The energy cost for maintenance of gradients of methylthio-beta-d-galactoside in Escherichia coli was evaluated. Information was also obtained concerning the energy flow associated with gradient establishment under some circumstances. Energy flow was evaluated from transport-induced changes in the rate of heat evolution, oxygen consumption, and carbon dioxide production in metabolically active cells. Heats were measured with an isothermal calorimeter. Energy expenditure behavior was characterized by a transition that depended on the level of accumulation. The data for steady-state maintenance could be rationalized in terms of the Mitchell hypothesis, two models for influx and efflux, and a transition between them. At low levels of uptake, steady-state proton-methylthio-beta-d-galactoside (TMG) symport for influx and efflux occurred via a nonenergy-requiring exchange process. The only energy requirement was that necessary to pump back in any TMG exiting via a leakage pathway (model I). Above the transition, all influx occurred with proton symport, but all exit, leak and carrier mediated, occurred without proton symport (model II). The H(+)/TMG stoichiometric ratio computed for the region of model II applicability (carbon source present, high level of uptake) approached 1. This value agreed with that of other workers for downhill beta-galactoside flow, suggesting that the energy cost for both downhill and uphill flow was approximately the same. For low levels of uptake, initial establishment of the gradient was followed by a burst of metabolism that was much larger than that expected on the basis of the chemiosmotic hypothesis. In the absence of carbon source, the stimulation in respiration was sufficient to produce 13 times more protons than are apparently necessary to establish the gradient. The results indicate also that the nature of the biochemical process stimulated by TMG depends on its level of uptake. Insight into several aspects of the nature of these processes was provided through analysis of the heat, oxygen, and CO(2) data. The key factor controlling the transition in energy flow behavior is suggested to be rate of flux. The present data suggest that it occurs at a flux of approximately 120 nmol/min per mg of protein.

The pulmonary vasoconstriction response to hypoxia was studied in eight anaesthetized supine subjects. One lung was made hypoxic while the other was ventilated with 100% oxygen. This was achieved by separating the tidal gas-distribution to the lungs by means of a double-lumen tracheal catheter. The hypoxic pulmonary vasoconstriction (HPV) response was estimated from the blood flow diversion away from the hypoxic lung. Blood flow distribution between the lungs was calculated from the regional expired carbon dioxide production, assuming regional carbon dioxide production to be proportional to blood flow. The subjects were studied during six different conditions. Firstly, when ventilated with 100% oxygen to both lungs at a PaCO2 of about 6 kPa. Secondly, with 100% oxygen to the left lung and 5% oxygen in nitrogen to the right (test) lung. The ratio between carbon dioxide output from right and left lung was calculated. These measurements were repeated during two states of hyperventilation (PaCO2 of about 4.5 kPa and 3.5 kPa, respectively) with and without hypoxia (conditions 3-6). During normoventilation, blood flow distribution between the lungs was equal. During hypoxia, blood flow distribution to the hypoxic lung decreased by 35% of the pre-hypoxic value. Furthermore, a decrease in arterial oxygen tension from 51.5 +/- 4.5 to 11.5 +/- 2.1 kPa was observed. During excessive hyperventilation (PaCO2 3.2 +/- 0.2 kPa), blood flow distribution to the hypoxic right lung decreased by only 10% of its pre-hypoxic value. A further decrease in arterial oxygen tension to 8.5 +/- 1.8 kPa was observed. This decrease in PaO2 was possibly due to an increased venous admixture caused by an abolished HPV response. It is concluded that hyperventilation counteracts hypoxic pulmonary vasoconstriction in man.

A mutant cell line derived from Chinese hamster fibroblasts is described which is defective in oxidative energy metabolism. Glucose is continuously required in the medium. As a result of a block in the Krebs cycle, these cells are auxotrophs for carbon dioxide and asparagine. Several experiments support our conclusion that the mutant cells lack appreciable levels of succinate dehydorgenase activity. Other components of the electron transport chain appear to be fully functional, although there is the possibility that electron transport and oxidative phosphorylation are uncoupled.

The turnover rates of water and carbon dioxide have been estimated at frequent intervals after a single dose of 2H2 18O had been given to an adult monitored continuously in a whole body calorimeter for 5 d. The integrated CO2 production rate for 5 d, estimated from the differential rates of 2H and 18O excretion in urine, was within 2 per cent of the actual CO2 output, based on an improved method of calculation. Changes occurred in the abundance of 2H and 18O in response to activity, so that the timing of samples was important. It was found better to compute the production rate of CO2 from multiple samples rather than from measurements at only two points of time. The proportion of total water lost by evaporation proved to be less than previously assumed. Direct validation of the technique requires calorimetric studies of 2 to 3 weeks duration, in either animals or human subjects. The potential value of this method for measurement of energy expenditure in man is such that exacting tests of its accuracy and precision are needed before it is adopted for general use in metabolic and epidemiological studies.

A method, based on quantitating 14CO2 produced from [14C]hexadecane, has been developed for estimating the rate of hexadecane decomposition in seawater of Tokyo Bay during the summer stagnation period. The rate of hexadecane decomposition was from 0.1 to 1.3 mug/h per liter of seawater at the surface layer in the polluted gyre of the inner part of Tokyo Bay during the summer of 1974. A similar horizontal distribution pattern was seen for the density of hexadecane-decomposing bacteria.

The carbon dioxide production of the chick embryo cultured in vitro has been determined during the first 24 h of post-laying development using a non-invasive conductometric microtechnique. The mean CO2 production of the whole blastoderm (1) increased from 16 nmol/h at laying to 231 nmol/h at early neurulation, (2) became dependent on exogenous glucose and (3) was closely linked to mechanical tension generated in the blastoderm (loosening from vitelline membrane resulted in a decrease of 56%). In our experimental conditions, no significant influence of carbonic anhydrase on the CO2 production has been detected. The value of the respiratory exchange ratio varied from about 3 at pregastrular stages to 1 at neurula stage and CO2 was produced transiently in presence of antimycin A. Such results indicate that the source of CO2 is not exclusively mitochondrial and that the relative proportions of mitochondrial and non-mitochondrial CO2 productions might vary significantly throughout the early development. Our findings confirm that the metabolism of the chick embryo becomes more and more oxidative from laying onwards and suggest that the modifications of metabolism observed during the studied period of development could be associated with functional differentiation.

The biodegradability of seven different crude oils was found to be highly dependent on their composition and on incubation temperature. At 20 C lighter oils had greater abiotic losses and were more susceptible to biodegradation than heavier oils. These light crude oils, however, possessed toxic volatile components which evaporated only slowly and inhibited microbial degradation of these oils at 10 C. No volatile toxic fraction was associated with the heavier oils tested. Rates of oil mineralization for the heavier oils were significantly lower at 20 C than for the lighter ones. Similar relative degradation rates were found with a mixed microbial community, using CO2 evolution as the measure, and with a Pseudomonas isolate from the Arctic, using O2 consumption as the measure. The paraffinic, aromatic, and asphaltic fractions were subject to biodegradation. Some preference was shown for paraffin degradation, especially at low temperatures. Branched paraffins, such as pristane, were degraded at both 10 and 20 C. At best, a 20% residue still remained after 42 days of incubation. Oil residues generally had a lower relative percentage of paraffins and higher percentage of asphaltics than fresh or weathered oil.

The effects of cyclopropane carboxylate on gluconeogenesis and pyruvate decarboxylation from [1-14C]-labeled pyruvate and lactate were investigated in perfused livers from fasted rats. With high concentrations of pyruvate (greater than or equal to 0.5 mM) in the perfusion medium, infusion of cyclopropane carboxylate inhibited pyruvate decarboxylation and gluconeogenesis by 30 and 40%, respectively. With low, more physiological concentrations of pyruvate (50 microM) or with lactate (1 mM), cyclopropane carboxylate, at a concentration which elicits maximal inhibition of pyruvate decarboxylation from pyruvate (greater than or equal to 0.5 mM), did not affect either pyruvate decarboxylation or gluconeogenesis. Evidence is presented for the rapid formation of the coenzyme-A ester of cyclopropane carboxylate in perfused livers. Infusion of l-(-)carnitine (20 mM) prevented the inhibitory effects of cyclopropane carboxylate on pyruvate decarboxylation and gluconeogenesis from pyruvate (greater than or equal to 0.5 mM). Interestingly, no decrease in the tissue level of cyclopropanecarboxyl-CoA occurs under these conditions. The present study suggests that cyclopropane carboxylate, through a presently ill-defined mediator, inhibits pyruvate decarboxylation and gluconeogenesis by interfering with the pyruvate----oxalacetate----phosphoenolpyruvate----pyruvate cycle when pyruvate (greater than or equal to 0.5mM) supports gluconeogenesis.

Pulmonary and cutaneous O2 consumption (Vo2) and CO2 production (Vco2) were measured simultaneously in bullfrogs Rana catesbeiana at 20 degrees C. The lungs were responsible for 77.3-91.0% of the total Vo2 and 28.5-74.9% of the total VCO2. The distribution of the total exchange between the lungs and skin depended on metabolic rate; frogs with higher rates relied more heavily on the pulmonary mode for both Vo2 and Vco2. When prevented from ventilating their lungs in an O2-rich environment, bullfrogs developed severe respiratory acidosis, demonstrating the importance of lung exchange in normal acid-base balance. When frogs were totally submerged in an O2-saturated medium, skin Vco2 increased linearly to a steady-state value which approximated the preapneic total Vco2. In these same animals, arterial Pco2 increased proportionately to the increase in skin Vco2, indicating that skin diffusion capacity for CO2 was unaffected. We conclude that the control of breathing in the bullfrog in response to changes in metabolic rate relies predominantly on changes in lung ventilation while the skin plays a more passive role.

The purpose of these experiments was to determine whether reported changes in substrate metabolism by isolated glomeruli from rats with aminonucleoside nephrosis could be explained by the glomerular changes associated with proteinuria or, alternatively, whether these metabolic changes and proteinuria were synchronous but causally unrelated events. Aminonucleoside of puromycin produced proteinuria within 7 days when injected intraperitoneally or subcutaneously. However, when aminonucleoside of puromycin as well as adenine were given, the onset of proteinuria was delayed until after day 7. A significant reduction in U-14C-glucose oxidation to CO2 was found at day 7 by glomeruli from rats given aminonucleoside of puromycin intraperitoneally but no significant changes were found with aminonucleoside of puromycin given subcutaneously on days 7 and 9 and aminonucleoside of puromycin + adenine given subcutaneously on days 7 and 9. Rats given daunomycin or adriamycin had developed proteinuria by day 14. U-14C-glucose oxidation to CO2 was significantly reduced on day 14 in glomeruli from rats given daunomycin but no significant changes were found on day 21 with daunomycin, or on days 14 and 21 with adriamycin. There was a reduction in pyruvic-acid carbon metabolism but not in glutamine-carbon oxidation 14 days after treatment with daunomycin. These results suggest that the observed changes in glomerular metabolism occur independently of, albeit synchronous with, the development of proteinuria. A causal relationship between these metabolic alterations and proteinuria therefore may be unlikely.

Rickettsia typhi cultivated in the yolk sac of chicken embryos or in L cells irradiated 7 days previously was separated from host cell components by two cycles of Renografin density gradient centrifugation. Preliminary steps involved differential centrifugation and centrifugation over a layer of 10% bovine plasma albumin of infected yolk sac suspensions, or trypsinization and passage through filters of wide porosity of infected L cell suspensions. Rickettsial preparations obtained by these methods appeared to be free from host cell components while retaining high levels of hemolytic activity, egg infectivity, and capacity to catabolize glutamate. Average yields were 3.3 mg of rickettsial protein per yolk sac or 0.44 mg per 16-oz (ca. 475-ml) L cell culture. Extracts from these two preparations displayed malate dehydrogenase activity of electrophoretic mobility identical to each other but quite different in migration patterns from the corresponding host cell enzymes. This method of separation of rickettsiae from host cell constituents appears to be particularly well suited for the study of rickettsial enzymatic activity.

The timing and relative participation of concurrent pathways of carbohydrate metabolism as well as the extent of terminal respiratory activity were determined by radiorespirometry with 14-C substrates and by enzyme assays for vegetative and sporulating cells of the bacterium Bacillus popilliae cultured in whole, intact Popillia japonica (Japanese beetle) larvae. During vegetative proliferation, the pentose phosphate pathway predominates in the bacterial cells with minor involvement of the Embden-Meyerhof-Parnas pathway. As the cells proceed through sporulation, pentose phosphate and Embden-Meyerhof-Parnas activity remains constant. No tricarboxylic cycle activity is evident during growth and sporulation of B. popilliae. The results demonstrate (i) predominantly aerobic metabolism for carbohydrate assimilation within in vivo sporulating cells, (ii) a major contrast to the metabolism of other aerobic sporeforming bacteria that exhibit derepression of tricarboxylic acid cycle enzymatic activity at the onset of sporulation, and (iii) no causal necessity of the cycle to B. popilliae sporogeny.

The formation of carbon dioxide, expressed as milligrammes of carbon dioxide per gramme wet weight, was used to determine the rate of succinate-induced respiration in rat incisal dental pulp, after incubation in a phosphate buffer. Seven experimental parameters: (a) physical nature of the tissue; (b) mass of the rat; (c) pre-incubation time; (d) incubation time; (e) substrate concentration; (f) effect of pH; and (g) effects of technique on pH, were analysed; pH was a critical determinant for success with this assay.

The role of catecholamines in shock metabolism in dogs was studied by comparing the metabolism of shock due to cardiac tamponade, shock with catecholamine depletion from prior reserpine adminstration and metabolism in the normal dog with continuous epinephrine infusion. It was concluded that the high serum concentrations of catecholamines in shock probably cause the increased blood lactate, initial hyperglycemia and, possibly, the poor free fatty acid oxidation seen in shock, but do not cause the increased protein catabolism of shock. With the simultaneous infusion of glucagon, cortisol and epinephrine in physiologic dosages, catabolic metabolism similar to that observed in shock was established in the normal dog. Lactacidemia, hyperglycemia, poor ability to oxidize free fatty acid and massive protein breakdown were observed. The decreased metabolic rate and diminished fatty acid mobilization of shock were not duplicated in those in the normal group and are probably a function of hypoperfusion. The importance of these observations is that impaired use of fat and increased protein breakdown, as seen in shock and trauma, are mediated by hormonal changes. It follows that there may be the opportunity to reverse or modify this catabolism by hormonal manipulation in the surgical patient.