Effect of carbostimulin on acid-base equilibrium of the blood of racing horses during exertion

The paper deals with possibility to regulate in a proper direction the acid-base state in race horse blood administering carbostimulin at rest and under physical exercises. The preparation is shown to favour an increase in alkaline blood reserves in race hours at rest and to prevent acidotic changes caused by physical exercises. The results obtained show a promising use of carbostimulin for the directed correction of the acid-base state of blood in race horses aimed at increasing the efficiency of the training process.     

Metabolic system of acid-base homeostasis in the human and animal body

Peculiarities of carbohydrate, lipid, amino acid nucleotide metabolism, of the tricarboxylic acid cycle functioning and of the oxidative phosphorylation have been studied in man and animals under conditions of changes in the acid-base equilibrium (ABE) state in the organism. The results of studies are analyzed and generalized. Strictly defined peculiarities of changes in the mentioned aspects of metabolism depending on the ABE state in the organism are revealed. Basing on a new interpretation of the experimental data and detected regularities in the metabolism, the author has drawn a conclusion on the existence of the previously unknown system of acid-base homeostasis in tissues. The physiological sense of this system functioning is the regulation of the intracellular acid-base equilibrium stability. The regulation mechanisms promoting functioning of this system are discussed. The system is shown to be of great applied significance for improvement of methods to cure a number of human and animal diseases as well as for an increase of the productivity of animals.     

Glutamic acid 160 is the acid-base catalyst of beta-xylosidase from Bacillus stearothermophilus T-6: a family 39 glycoside hydrolase

A beta-xylosidase from Bacillus stearothermophilus T-6 was cloned, overexpressed in Escherichia coli and purified to homogeneity. Based on sequence alignment, the enzyme belongs to family 39 glycoside hydrolases, which itself forms part of the wider GH-A clan. The conserved Glu160 was proposed as the acid-base catalyst. An E160A mutant was constructed and subjected to steady state and pre-steady state kinetic analysis together with azide rescue and pH activity profiles. The observed results support the assignment of Glu160 as the acid-base catalytic residue.     

Changes in the levels of various substrates of nitrogen metabolism and tricarboxylic acid cycle during experimental acidosis in calves

The effect of experimental metabolic acidosis and its correction for nitrogen and energy metabolism was studied in new-born calves. It was discovered that a change in the acid-base balance towards acidosis causes a sharp increase in "ammoniogenesis", urea formation and inhibition of the tricarboxylic acid cycle, which is also observed in calves suffering from dyspepsia with symptoms of acute diarrhea. Alongside with the use of therapeutic measures for treating dyspepsia of new-born calves, it is necessary to control the acid-base balance of blood in the calves and in case of revealing the acidosis state to use means of its correction.     

Fluorescence studies on the photophysical properties and encapsulation behavior of acetaminophen in different environments

A systematic study on the spectroscopy and photophysical properties of widely used analgesic and anti-pyretic drug acetaminophen (NAPAP) was presented using steady state and time-resolved fluorescence spectroscopy. The results in homogeneous solvents were compared with those in bio-mimicking environments of cyclodextrin and micellar cavities. Extensive theoretical calculations using time dependent density functional theory (TDDFT) were also done to substantiate the spectral assignment as well as to compare the structure and stability of possible hydrogen bonded conformations of NAPAP in aqueous medium. Facile proton dissociation occurs due to extensive charge redistribution in the excited state. The variation in fluorescence yield and the life time of excited state species in cyclodextrin cavities and micellar medium is due to shift in acid-base dissociation equilibrium in these environments.     

Salt hydrates for in situ water activity control have acid-base effects on enzymes in nonaqueous media

Salt hydrates very frequently are utilized as in situ water activity buffers in reaction mixtures of enzymes in nonaqueous media. In addition to buffering water activity, there is evidence that salt hydrates also often affect initial rates in other ways. This has been generally overlooked or thought to be related to water transfer effects. Here we show that salt hydrates can have important acid-base effects on enzymes in nonaqueous media. We performed transesterification reactions in n-hexane and in supercritical ethane catalyzed by cross-linked crystals of subtilisin, differing in the method used to set a(W), and confirmed that the presence of salt hydrate pairs significantly affected the catalytic performance of the enzyme. However, in the presence of a solid-state acid-base buffer, salt hydrates had no effect on enzymatic activity. Direct evidence for the acid-base effects of salt hydrates was obtained by testing their effect on the protonation state of an organo-soluble H(+)/Na(+) indicator. The four salt hydrate pairs tested affected the indicator to very different extents. By promoting the exchange of H(+) for Na(+), salt hydrates will tend to affect the ionization state of acidic residues in the protein and, hence, enzymatic activity. In fact, salt hydrates were able to affect the pH memory of subtilisin lyophilized from different aqueous pHs, bringing about up to 20-fold enhancements and up to 5-fold decreases in catalytic activity. The possibility of such acid-base effects need to be considered in all experiments using salt hydrates to control water activity.     

A mathematical model of blood-interstitial acid-base balance: application to dilution acidosis and acid-base status

We developed mathematical models that predict equilibrium distribution of water and electrolytes (proteins and simple ions), metabolites, and other species between plasma and erythrocyte fluids (blood) and interstitial fluid. The models use physicochemical principles of electroneutrality in a fluid compartment and osmotic equilibrium between compartments and transmembrane Donnan relationships for mobile species. Across the erythrocyte membrane, the significant mobile species Cl? is assumed to reach electrochemical equilibrium, whereas Na(+) and K(+) distributions are away from equilibrium because of the Na(+)/K(+) pump, but movement from this steady state is restricted because of their effective short-term impermeability. Across the capillary membrane separating plasma and interstitial fluid, Na(+), K(+), Ca2(+), Mg2(+), Cl?, and H(+) are mobile and establish Donnan equilibrium distribution ratios. In each compartment, attainment of equilibrium by carbonates, phosphates, proteins, and metabolites is determined by their reactions with H(+). These relationships produce the recognized exchange of Cl(-) and bicarbonate across the erythrocyte membrane. The blood submodel was validated by its close predictions of in vitro experimental data, blood pH, pH-dependent ratio of H(+), Cl?, and HCO?? concentrations in erythrocytes to that in plasma, and blood hematocrit. The blood-interstitial model was validated against available in vivo laboratory data from humans with respiratory acid-base disorders. Model predictions were used to gain understanding of the important acid-base disorder caused by addition of saline solutions. Blood model results were used as a basis for estimating errors in base excess predictions in blood by the traditional approach of Siggaard-Andersen (acid-base status) and more recent approaches by others using measured blood pH and Pco? values. Blood-interstitial model predictions were also used as a basis for assessing prediction errors of extracellular acid-base status values, such as by the standard base excess approach. Hence, these new models can give considerable insight into the physicochemical mechanisms producing acid-base disorders and aid in their diagnoses.     

CO2 mass transfer and acid-base balance under conditions of muscular activity at sea level and in the mountains

The state of the blood acid-base balance and dynamics of carbonic acid gas mass transfer were studied in sportsmen at the sea level and in mountains. It is shown that at the sea level due to an intensive muscular activity large amounts of CO2 are formed and excreted; the mass transfer of this gas is multiply accelerated, simultaneously, a pronounced decompensated metabolic acidosis is observed which in some cases is complicated respiratory acidosis. The similar exercises in mountains are followed by a more pronounced disturbance in the acid-base balance and a more intensified mass-transfer of CO2. After 12-day acclimatization and training in mountains the buffer blood capacity increases, the metabolic acidosis under conditions of muscular activity is less pronounced.     

What is the ultimate goal in acid-base regulation?

It is common to see chapters on acid-base physiology state that the goal of acid-base regulatory mechanisms is to maintain the pH of arterial plasma and not arterial Pco(2) (Pa(CO(2))) or plasma HCO(3). A hypothetical situation in which the Pa(CO(2)) of arterial plasma is 80 mmHg and the plasma HCO(3) concentration is 48 mM is presented and analyzed to get over this misconception. As per the modified Henderson equation, the pH of arterial plasma would be 7.4; however, we explain that this may be associated with intracellular acidosis due to intracellular hypercapnia and that derangement of homeostasis is evident from the occurrence of respiratory depression and, eventually, coma in the patient described. This suggests that the ultimate goal of acid-base regulatory mechanisms is not just the maintenance of the pH of arterial plasma but the maintenance of the steady-state pH of intracellular fluid as well.     

Characteristics of the acid-alkali equilibrium in blood of experimental animals in response to exposure of 'murine' toxin and Yersinia pestis capsular antigen

As revealed in this study, metabolic acidosis is observed in experimental animals the influence of "murine" toxin and Y. pestis fraction I, which is manifested by the parameters of the acid-base state, the gas composition of blood and the content of electrolytes.     

Role of sodium on H+ excretion in the integument of the leopard frog Rana pipiens

1. The northern leopard frog, Rana pipiens, pipiens, in contrast to the southern leopard frog, Rana pipiens, berlandieri, did not demonstrate any significant H+ excretion across its integument even during a challenge of chronic metabolic acidosis. Likewise, no increase in the number of H+ secreting mitochondria-rich cells were observed in the northern frogs. 2. Under normal acid-base conditions in the southern frogs, H+ excretion was found to be dependent on mucosal sodium concentrations, whereas during chronic metabolic acidosis, H+ excretion was independent of mucosal sodium concentrations, but was amiloride sensitive. 3. High salinity adapted southern frogs, under normal and acidotic conditions, had enhanced H+ excretion rates as compared to the control non-salt adapted frogs. 4. Blood analyses demonstrated that significant acid-base changes were the result of systemic acidosis and not due to salt adaptations. Blood Na+ and K+ concentrations were also efficiently maintained during salt adaptations or chronic metabolic acidosis. 5. The results suggest that H+ excretion in epithelia can be influenced by the sodium transport state of the cell and the systemic acid-base profile. Models are proposed explaining these relationships.     

The association between K+ and H+ distribution in skeletal muscles: implication to linked transport.

Data from the literature and results from a mathematical model of steady state fluid-electrolyte balance are used to support the observation that a relationship exists between the concentration gradients of K⁺ and H⁺ in the fluids of skeletal muscle over a range of acid-base disturbances. This relationship is shown to be consistent with the premise that the steady state electrochemical potential gradients for these ions remain constant under these conditions. Using a pump-leak model of ion transport, and the constant electric field assumption, it is also demonstrated that the steady state rates of active transport of K⁺ and H⁺ are related. These results suggest that the relations between both the steady state concentration gradients and the active transport rates for these ions are not necessarily the result of fixed biochemical mechanisms, but may come about simply from coupling through macroscopic thermodynamic processes.     

1株产酸碱指示剂的真菌的鉴定

采用形态学和分子生物学鉴定的方法,对1株产生酸碱指示剂的真菌进行鉴定.结果表明,该菌株的子囊壳呈球形或卵形,单生或聚生,子囊孢子双胞,无色,椭圆形,分隔处稍缢缩,无性态为串珠镶孢.通过该菌株rDNA ITS的PCR扩增和序列测定,与NCBI网站进行同源性比对分析,结果表明待测菌株与藤仓赤霉菌(Gibberella fujikuroi)同源性为100％,确定该菌株为蘑仓赤霉菌.     

Effect of carotid body resection on ventilatory and acid-base control during exercise.

To investigate the role of the carotid bodies in exercise hyperpnea and acid-base control, normal and carotid body-resected subjects (CBR) were studied during constant-load and incremental exercise. There was no significant difference in the first-breath ventilatory responses to exercise between the groups; some subjects in each reproducibly exhibited abrupt responses. The subsequent change in Ve toward steady state was slower in the CBR group. The steady-state ventilatory responses were the same in both groups at work rates below the anaerobic threshold (AT). However, above the AT, the hyperpnea was less marked in the CBR group. Ve and acid-base measurements revealed that the CBR group failed to hyperventilate in response to the metabolic acidosis of either constant-load or incremental exercise. We conclude that the carotid bodies 1) are not responsible for the initial exercise hyperpnea, 2) do affect the time course of Ve to its steady state, and 3) are responsible for the respiratory compensation for the metabolic acidosis of exercise.     

Effect of carbostimulin on indices of acid-base balance and lactate concentration in the blood of swimmer-athletes

It is studied how 10-12-day taking of carbostimulin influences the acid-base equilibrium indices and lactate content in blood of swimmer sportsmen before and after the interval anaerobic loading and in the restoration period. It is found that the preparation promotes a faster removal of the acidosis state developing in sportsmen under the effect of intensive physical exercises.     

Effects of diet on titratable acid-base excretion in grasshoppers

Despite the potential for diet to affect organismal acid-base status, especially in herbivores, little is known about the effects of diet on acid-base loading and excretion. We tested the effects of diet on acid-base loading and excretion in grasshoppers by (a) comparing the fecal acid-base content of 15 grasshopper species collected from the field and (b) comparing fecal acid-base excretion rates of Schistocerca americana grasshoppers fed vegetable diets that differed in their ashed and raw acid-base contents. The field experiments indicated that grass-feeding species excrete fairly neutral fecal pellets, while forb/mixed-feeding species vary widely in their fecal acid-base contents. In the laboratory experiment, acid-base excretion rates were positively correlated with dietary ashed base intake rates but were not correlated with the acid-base content of raw, unashed diet or feeding rate. These experiments suggest that some diets could strongly challenge the acid-base homeostasis of herbivores; in some grasshoppers, dietary acid-base loads could produce certainly lethal 1-unit changes in average body pH within 6 h if they were not excreted.     

Mechanism of metabolic adaptation

The paper presents results of investigations on some mechanisms of metabolic adaptation in mammals. There are four sections in the tissue metabolic system of acid-base homeostasis: polyamines as factors of metabolic adaptation; significance of carbon dioxide for metabolic response formation in hypobiosis; polyamines metabolism in hypobiosis. Peculiarities of intermediate metabolism have been analyzed in animal tissues under the changes in H+, CO2 and HCO3- concentrations. Basing on a new interpretation of the experimental data and detected regularity in the metabolism, conclusion on the existence of a new acid-base homeostasis system in the tissues has been made. The results of polyamines metabolism investigations in the mammals under the stress have been described. The experimental data make us to believe that changes in polyamines synthesis and ODC activity in particular, is a part of stereotype nonspecific response to any stress impacts and one of the factors of cell metabolic adaptation. Some new data on mechanisms of formation and control of metabolic status of animals in the natural and artificial hibernation have been presented. The key idea is that in the state of hypobiosis the carbon dioxide (HCO3-) appears as a regulatory factor of metabolic adaptation, which is able to realize its action directly via affecting numerous biochemical events. The participation of polyamines in adaptive metabolic response to hybernation factors is suggested. Some peculiarities of ornithine decarboxilase and transglutaminase activity during the different stages of genuine and artificial hypobiosis have been demonstrated.     

Three-way multivariate curve resolution applied to speciation of acid-base and thermal unfolding transitions of an alternating polynucleotide.

Analytical speciation of acid-base equilibria and thermal unfolding transitions of an alternating random polynucleotide containing cytosine and hypoxanthine, poly(C, I), is studied. The results are compared with those obtained previously for single-stranded polynucleotides, poly(I) and poly(C), and for the double-stranded poly(I). poly(C), to examine the influence of the secondary structure on the acid-base properties of bases. This study is based on monitoring acid-base titrations and thermal unfolding experiments by molecular absorption, CD, and molecular fluorescence spectroscopies. Experimental data were analyzed by a novel chemometric approach based on a recently developed three-way Multivariate Curve Resolution method, which allowed the simultaneous analysis of data from several spectroscopies. This procedure improves the resolution of the concentration profiles and pure spectra for the species and conformations present in folding-unfolding and acid-base equilibria. The results from acid-base studies showed the existence of only three species in the pH range 2-12 at 37 degrees C and 0.15M ionic strength. No cooperative effects were detected from the resolved concentration profiles, showing that equilibria concerning alternating polynucleotides like poly(C, I) are simpler than those involving poly(I). poly(C). Thermal unfolding experiments at neutral pH confirmed the existence of two transitions and one intermediate conformation. This intermediate conformation could only be detected and resolved without ambiguities when molecular absorption and CD spectral data were analyzed simultaneously.     

Cholesterol esterase catalyzed hydrolysis of mixed micellar thiophosphatidylcholines: a possible charge-relay mechanism

Mechanistic features of cholesterol esterase catalyzed hydrolysis of two thiophospholipids, rac-1-(hexanoylthio)-2-hexanoyl-3-glycerophosphorylcholine (6TPC) and rac-1-(decanoylthio)-2-decano-yl-3-glycerophosphorylcholine (10TPC), have been characterized. The hydrolysis of 10TPC that is contained in mixed micelles with Triton X-100 occurs strictly at the micellar interface, since the reaction rate is independent of the micelle concentration but depends hyperbolically on the mole fraction of the substrate in the micelles. This latter observation allows one to calculate the interfacial kinetic parameters V*max and K*m. The hydrolyses of 10TPC and p-nitrophenyl butyrate are similarly inhibited by the transition state analogue inhibitor phenyl-n-butylborinic acid, and therefore, physiological and nonphysiological substrates are processed at the same active site. The similarity of k*cat values for the acyl-similar substrates 10TPC and p-nitrophenyl decanoate indicates that the phospholipase A1 activity of cholesterol esterase is partially rate limited by turnover of a decanoyl-enzyme intermediate. Solvent isotope effects on V*max and V*max/K*m (which monitors acylation only) are approximately 2-3 and are consistent with transition states that are stabilized by general acid-base proton transfers. Proton inventories of V*max/K*m indicate that simultaneous proton transfers stabilize the acylation transition state, which requires a multifunctional acid-base machinery (perhaps a charge-relay system) in the cholesterol esterase active site. Similar results are obtained for the 6TPC reaction, both in the presence and absence of Triton X-100 micelles.     

ATP regeneration by thermostable ATP synthase

We investigated the possibility of using thermostable ATP synthase (TF(0)F(1)) for a new ATP regeneration method. TF(0)F(1) was purified from a thermophilic bacterium, PS3, and reconstituted into liposomes. ATP synthesis experiments showed that TF(0)F(1) liposomes could synthesize ATP in micromole concentrations by acid-base change. The acid-base change was repeated six times over an 11-day period with no detectable loss of activity at the reaction temperature (45 degrees C). Given these encouraging results, we conceptualized and modeled a system to synthesize ATP using ATP synthase with energy supplied by acid-base change. In this system, liposomes containing ATP synthase are immobilized on small glass spheres that facilitate separation of buffers from the liposomes after the acid-base change. Compared to an alternate system that uses membranes to separate the buffers from the liposomes, the glass spheres reduce inefficient mixing of acidic and basic buffers during the acid-base change. To increase the ATP synthesis yield, this system uses electrodialysis to regenerate a potassium gradient after the acid-base change. It also employs water-splitting electrodialysis to regenerate KOH and HCl required to adjust the pH of acidic and basic buffers. All reagents are recycled, so electrical energy is the only required input.