Meq Of Acid Research Articles

Neonatal acid base balance and disturbances

Maintaining acid base balance presents a considerable challenge to the growing neonate. The infant must ingest protein for growth and development. The metabolism of sulfur containing amino acids leads to the production of protons that must be secreted by the kidney. In addition, the formation of hydroxyapatite for the mineralization of growing bone also leads to acid production. Thus, the growing infant must excrete approximately 2 to 3 mEq of acid per kilogram of body weight per day to avoid becoming acidotic. The mechanisms for excreting acid undergo complex maturational changes that predispose the neonate, and the premature neonate in particular, to a great risk for the development of acidosis. In addition, infants are susceptible to gastrointestinal disturbances that can lead to acidosis due to acute loss of bicarbonate in the stool. The kidney is then responsible for the production of new bicarbonate to restore the body’s acid base balance. There are also a number of inherited disorders in the kidney that affect acid secretion and lead to acid base disturbances in neonates. This review discusses the mechanisms by which the kidney is capable of excreting acid as well as the developmental regulation of these processes and the basis of inherited disorders of acidification.

The chemistry of lava–seawater interactions: the generation of acidity

High concentrations of acid were found to arise from the interaction between molten rock and seawater at the shoreline of Kilauea Volcano, Hawaii. A series of field samplings and experiments show that the acid was derived from two sources: the release of magmatic volatiles and water–rock reactions. Although the bulk of the magmatic volatiles (CO2, H2O, and SO2) are vented at Puu Oo cinder cone before the lava’s transit downslope to the ocean, a portion of the sulfur (S) and fluoride (F) gasses are retained by the lava and then are released partially when the lava is quenched by seawater. The primary water–rock reaction responsible for acid formation appears to be Na-metasomatism, which is much different from the predominant acid-forming reaction found in submarine hydrothermal systems, Mg-metasomatism. Analyses of surface seawater and of precipitation (rain) deposited at the shore show that ∼30% of the acid comes from magmatic gasses with the balance from reactions between the rock and the salts found in seawater. Experimental results show that ∼4 ± 1.5 mEq of acid are formed per kilogram of lava entering the ocean, and of this 1 ± 0.5 mEq/kg of lava came from S and F, with the balance coming from water–rock reactions. On the basis of lava extrusion rates, ∼200–720 × 106 Eq/yr of acid are being formed at this site. The deposition of the acid results in the alteration of subaerial lava flows along the coast, and the lowering of the pH of the adjacent surface ocean waters by more than 1 unit. The ejection of this acid into the atmosphere contributes to the formation of an extensive haze downwind of the lava entries.

Sulphate, acid-base, and mineral balances of obese women during weight loss

Four obese women, each at least 50% above their expected weight for height were maintained in the metabolic unit for 63 days on liquid formula diets of differing protein and calorie content. We made the following findings: 1) When 12 g protein nitrogen was consumed, 1 mEq of acid was excreted in the urine for every 2 mEq of urinary sulphate. 2) On a protein-free diet more acid was excreted in the urine than could be accounted for by oxidation of sulphur to the sulphate which was excreted in the urine. 3) Both increased consumption of protein and a restriction of dietary calories was associated with an increase of urinary acid. 4) Urinary sulphur excretion was closely correlated with nitrogen intake and urinary urea nitrogen excretion. However, on a protein-free diet the ratio of total nitrogen to sulphur in the urine was greater than when 12 g protein nitrogen was consumed. 5) There is some evidence that when total calorie intake was reduced at a level of 12 g protein nitrogen intake, the ratio of urinary urea nitrogen to urinary sulfur decreased. This suggests selective retention of some nonsulphur containing amino acids and/or selective oxidation of sulphur-containing amino acids. 6) In general, urinary calcium and magnesium excretions were depressed both with a decrease in protein consumption and a decrease in caloric intake. 7) The urinary excretions of calcium and magnesium showed a tendency to fall during the 63 days of the experiment. 8) The urinary and fecal phosphorus excretion remained constant during the various metabolic periods of the experiment.

Solid Substrate Fermentation of Feedlot Waste Combined with Feed Grains

A new process is being developed for recycling animal wastes based on a solid substrate fermentation with cracked grains. To date, the work has been done mainly with corn and the liquid fraction of cattle feedlot waste. This liquid, separated by an oscillating 30 mesh screen, contains 10% solids in the form of microbial cells and either fine or soluble waste components; it has a nitrogen content of 3-4 mg/ml. When added to cracked corn at a ratio of 1:2, the thick liquid adheres to grain surfaces. Grain waste mixtures at about 40% moisture, incubated aerobically by tumbling in a slowly revolving (0.5 rpm) vessel, such as a small cement mixer, rapidly undergo an acid fermentation caused by the selective growth of lactic acid bacteria originally present in the waste; other waste organisms die. The number of bacterial cells increases 100 fold with 24 hr; yeasts emerge after extended incubation. The fetid waste odor quickly disappears as 0.1 meq of acid per wet gram of fermented solids is generated while nitrogen is conserved. The acids formed are primarily lactic and acetic, with lesser amounts of propionic and butyric. Exploratory tests with milo and wheat, as well as with wastes from hogs and cattle on different rations, indicate that the new process may be widely applicable. Diluted whole waste may be used when inclusion of fiber in the fermented feed product is of no concern. The solid state system provides an easily established selective environment for microbial growth. Specific organisms and added inorganic nitrogen may be used for a continuous operation to generate higher protein content in grain based rations.

Effect of duodenal acidification on the gastric secretory response to pentagastrin in man.

Acidification of the duodenum of healthy young subjects with 40 mEq of acid during 1 h resulted in a 45-percent inhibition of acid output in response to 0.15 μg/kg/h of pentagastrin, but had no effect on acid output stimulated with 6.0 μg/kg/h of pentagastrin. There was no significant effect of duodenal acidification on the total output of pepsin. Since secretin stimulates pepsin secretion, endogenous secretin alone cannot account for the inhibition of acid secretion. Duodenal acidification with the subjects own gastric acid had no significant effect on gastric secretion. The physiological significance of the effects described seems, therefore, uncertain.

Characteristics of the vegetative growth of Bacillus popilliae.

Growth characteristics of the insect pathogen, Bacillus popilliae Dutky, were studied by propagation in shaken flasks and in 2-liter fermentors. Maximal populations between 5 x 10(8) and 2 x 10(9) viable cells per milliliter of culture medium routinely were obtained in incubation periods of 18 to 24 hr at 30 C in a medium composed of 1.5% yeast extract, 0.6% K(2)HPO(4), and 0.2% glucose or trehalose. The carbohydrate required for growth in liquid media was fermented with the formation of 2 meq of acid per mmole of carbohydrate utilized; acid products ordinarily were not subsequently metabolized. B. popilliae is an aerobe, and the amount of growth obtained varied with aeration to an optimum at oxygen absorption rates of about 0.5. Maximal populations persist in a culture for periods of only 1 to 4 hr; cessation of growth was followed immediately by rapid death of cultures, so that less than 1% of the cells remained viable after 48 hr, and viability often was lost entirely by the end of 72 hr of incubation. No cytological evidence for spore formation was observed under any growth condition. Death was not associated with lysis of the cells, although extensive granulation ultimately occurred. Continuous neutralizaiton, augmented buffering, various techniques of dialysis, or slow feeding of the carbohydrate did not markedly alleviate the characteristic death of the cultures.

Characteristics of the Vegetative Growth of Bacillus popilliae

Growth characteristics of the insect pathogen, Bacillus popilliae Dutky, were studied by propagation in shaken flasks and in 2-liter fermentors. Maximal populations between 5 x 10(8) and 2 x 10(9) viable cells per milliliter of culture medium routinely were obtained in incubation periods of 18 to 24 hr at 30 C in a medium composed of 1.5% yeast extract, 0.6% K(2)HPO(4), and 0.2% glucose or trehalose. The carbohydrate required for growth in liquid media was fermented with the formation of 2 meq of acid per mmole of carbohydrate utilized; acid products ordinarily were not subsequently metabolized. B. popilliae is an aerobe, and the amount of growth obtained varied with aeration to an optimum at oxygen absorption rates of about 0.5. Maximal populations persist in a culture for periods of only 1 to 4 hr; cessation of growth was followed immediately by rapid death of cultures, so that less than 1% of the cells remained viable after 48 hr, and viability often was lost entirely by the end of 72 hr of incubation. No cytological evidence for spore formation was observed under any growth condition. Death was not associated with lysis of the cells, although extensive granulation ultimately occurred. Continuous neutralizaiton, augmented buffering, various techniques of dialysis, or slow feeding of the carbohydrate did not markedly alleviate the characteristic death of the cultures.