Influence Of pH Changes Research Articles

The haemocyanic of Pila leopoldvillensis—I. preparation and study of the dissociation by zone electrophoresis and light scattering

1. 1. Pile leopoldvillensis, a gastropod of large size, living along the banks of the River Congo upstream of Kinshasa, has a haemocyanin of high molecular weight, 8·7 × 10 6 which has proven fairly stable. 2. 2. The purification and crystallization of the haemocyanin has been described. 3. 3. By means of electrophoresis on cellulose acetate, the homogeneity of the isolated product could be demonstrated, its dissociation under the influence of changes in pH and the reversibility of this dissociation. 4. 4. Light-scattering measurements indicate half-molecules and tenths for the successive dissociation products.

The influence of changes in pH of the perfusion fluid on the occurrence of the calcium paradox in the isolated rat heart.

During Langendorff perfusion of isolated rat hearts the minimum duration of the calcium-free perfusion period, after which reperfusion with calcium evokes the “calcium paradox”, is influenced by changes in pH of the perfusion fluid. This time interval is prolonged by a decreased pH and shortened by an increased pH.

Influence of Changes in pH on the Mechanical Activity of Cardiac Muscle

In a comprehensive experimental study, the influence of changes in extra-and intracellular pH on the mechanical and electrical activity of frog heart ventricle preparations has been investigated. The twitch tension and potassium contracture tension were decreased in acid solutions, provided that the concentration of calcium or the frequency of stimulation was low. In solutions with a high calcium concentration, prolonged exposure to acid leads to an increase of the potassium contractures. The electrical activity, measured by intracellular microelectrodes, is abolished in acid solutions if the change of solution in the extracellular space is enforced by perpendicular jet superfusion; with slow perfusion it is well maintained except when [Ca] is high. The lowering of intracellular pH by applying a solution saturated with 80% CO 2 while keeping the extracellular pH constant causes a rapid drop in twitch tension followed by partial recovery. The relaxation phase of single twitches is prolonged and potassium contractures are markedly increased after the high CO 2 has acted for several minutes. When both intra- and extracellular pH are decreased, both twitches and potassium contractures are markedly decreased. The electrical activity is maintained. Some of the effects of variations in pH are discussed in terms of changes in the processes of mechanical activation and inactivation.

The Reactions of Thrombin with Fibrinogen and Plasma Antithrombin

SummaryThe effects of pH, salt and amino acid (β-alanine) concentration on the rate of thrombin formation and antithrombin activity in recalcified plasma was studied from the viewpoint of reaction rate kinetics, and units of thrombin and antithrombin activity defined on this basis. Optimal thrombin activity (fibrin formation) was observed between pH 6.5 and 8.0 and at 0.19 M NaCl. Maximal antithrombin activity occurred at pH 8.5 and 0.10 M sodium chloride.Antithrombin activity, examined under optimal conditions as well as under the influence of changes in pH, and of salt and amino acid concentrations proved to follow first-order reaction kinetics. The activities of thrombin and antithrombin changed in a diphasic manner with increasing concentrations of salt or amino acid and such change may represent subtle protein-protein or protein-salt interactions.The antithrombin activity of fifteen normal plasmas was determined from reaction rate studies of thrombin destroyed during recalcification of human plasma and compared to the inactivation of bovine thrombin by citrated plasma.A concept of “coagulability” of plasma based on the measurement of two independent parameters, fibrinogen and antithrombin, and their kinetic interrelationships, was developed as an approach to a functional concept of hemostasis.

Oxidation Reduction Potential as a Control Criterion In Inhibition of Refinery Sulfide Corrosion

Abstract The effect of the sulfide on the corrosion of refinery crude unit overhead equipment is considered, using oxidation reduction potential (redox) as a criterion of sulfide content. The study shows that optimum operating conditions are established through careful injection of ammonia to control pH, redox, and sulfide content of the overhead water. Laboratory data are presented to show the influence of changes in pH and redox on corrosivity and on the effectiveness of various corrosion inhibitors. Application of the findings of this investigation to refinery practice is illustrated. 3.6.5, 8.4.3

Studies in neuromuscular transmission. III. Influence of changes in blood pH and carbon dioxide tension on the effect of tubocurarine and dimethyl tubocurarine.

The influence of changes in pH and the partial pressure of carbon dioxide in arterial blood on the neuromuscular blocking effect of a single dose of tubocurarine or dimethyl tubocurarine was investigated in rabbits. The sciatic nerve was stimulated supramaximally at a rate of 3 per second and the electrical response of the gastrocnemius muscle was recorded; the amplitude of the first and fourth response was measured. During the period of spontaneously subsiding block after a single injection of the blocking agent, a shift in the arterial pH was produced either with or without a change in carbon dioxide tension. An increase of the block during this period was always considered significant but a decrease of the block only if it was followed by a spontaenous increase. The action of tubocurarine increased during acidosis and diminished during alkalosis. This effect was greater during metabolic alkalosis and acidosis, corresponding to a more rapid shift in pH, than during respiratory alkalosis and acidosis, but no qualitative difference was observed. The effect of a shift in pH is explained by changes in the potency of tubocurarine. The action of dimethyl tubocurarine was not influenced by changes in pH or carbon dioxide tension.

Studies on Blood and Meat Spots in the Hen’s Egg , : 1. The Fluorescent Property of Meat Spots

ABSTRACT THE problem of blood and meat spots in shell eggs continues to be a serious one for the poultry industry. Economic losses from these defects are great, and when the development of automatic detecting devices is completed, the problem will become even more intensified from the standpoint of the breeder and producer. The need for additional research in this area is quite apparent. Burmester and Card (1938) concluded from histological studies that meat spots consisted merely of red blood cells in various stages of degeneration. In vitro studies by Nalbandov and Card (1944) suggested that meat spots resulted from the transformation of blood clots under the influence of changes in pH and high environmental temperatures, either prior to ovulation, during egg formation, or even after oviposition. Blood spot formation was attributed to hemorrhages in the space between the follicular wall and the vitelline membrane before ovulation. These theories on blood . . .

The Relationship of Shell Color to Incidence of Blood and Meat Spots in Hens’ Eggs

A RELATIONSHIP between egg shell color and incidence of colored meat spots was reported by Jeffrey and Walker (1950). In their work they compared eggs from four different breeds, three producing brown shelled eggs and one producing white shelled eggs. They also questioned the interpretation made by Nalbandov and Card (1944) that meat spots result from the transformation of blood clots under the influence of changes in pH at high environmental temperatures.The purpose of the work reported in this paper was to obtain additional data on this problem.For this work, eggs from White Olympians, a new breed of chickens being developed at this Station, were used. Hens from this breed produce eggs with shell colors ranging from white to dark brown. Eggs were obtained from the flock of hens at three times: January, 1951; October, 1951; and January, 1952. All eggs were broken within 3 days after being .

The influence of pH on the enzymatic decarboxylation of oxalacetic acid

The pH-activity curve of the oxalacetic carboxylase of Cucurbita pepo seeds which catalyzed the decarboxylation of oxalacetic acid was examined for the possible factors whose variation with pH might be responsible for the shape of the curve between pH 3.5–5.0. 1. 1. It was shown that the shape of the curve remains essentially the same regardless of whether the reactions were conducted in buffers of constant ionic strength or of constant molarity. However, ionic strength had a definite effect on the over-all rate of the enzymatic reaction. 2. 2. The decrease in enzymatic activity between pH 4.2 and 5.0 was compared with the solubility of the squash seed protein in this pH range. The two were shown to parallel one another closely. 3. 3. The influence of changes in pH in the acid-base binding power of the cucurbit protein was examined, and the bearing of this factor on enzymatic activity was discussed. It was shown experimentally that no irregular changes in the titration curve of the protein occur within the range of enzymatic activity. 4. 4. The relationship between the availability of the uni- and bivalent anions of oxalacetic acid and the rate of the enzymatic reaction between pH 3.5–4.2 was examined. The rate was shown to be directly proportional to the bivalent anion concentration and inversely proportional to the univalent anion concentration under a variety of conditions. These facts led to the postulation that the increase in reaction rate between pH 3.5–4.2 is the result of increasing concentration of bivalent anion and decreasing concentration of univalent anion. 5. 5. The significance of these findings with regard to the mechanism of enzymatic decarboxylation of oxalacetic acid is discussed.

The Relationship between Egg Shell Color and Incidence of Colored Meat Spots

VAN WAGENEN, Hall, and Wilgus (1937) reported that “eggs from the American breeds studied showed a much greater incidence of meat spots than did those from the Single Comb White Leghorn. No differences in the occurrence of blood spots were observed among the breeds”. Jeffrey (1945) working with Single Comb White Leghorns, Single Comb Rhode Island Reds, Barred Plymouth Rocks, and Legbars confirmed these observations.Nalbandov and Card (1944) proposed a view of meat spot formation which may be summarized as follows: “meat spots result from the transformation of blood clots, under the influence of changes in pH and high environmental temperatures, either prior to ovulation or during egg formation, or even after the egg is laid.” Card and Nalbandov (1944) reported that the average incidence of meat spots for their strains of Single Comb White Leghorns was 12.8 percent and for their heavy breeds 6.1 percent. In these same .

Blood and Meat Spots in Chicken Eggs

INTRODUCTIONIN A RECENT paper Nalbandov and Card (1944a) reviewed the literature on blood and meat spots in chicken eggs. The proposed that “hemorrhages causing the formation of blood clots in eggs occur before ovulation” and that “meat spots result from the transformation of blood clots, under the influence of changes in pH and high environmental temperatures, either prior to ovulation or during egg formation, or even after the egg is laid.” Observations at the New Jersey Station during 1943–1944 on eggs from four breeds of chickens have supplied evidence which confirms this theory of the formation of meat spots.PROCEDUREAll eggs laid by 166 pullets, hatched in late May or mid-June, were broken out and observed for the presence or absence of blood and meat spots. The observational period extended from November 1 through August 31. Forty of the pullets were Rhode Island Reds kept under so-called .