Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0847097 (acidity)
 15,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of variables associated with the donor and with methods of collecting, processing, and storing platelets on the quality of platelets kept at ambient temperature was studied. Changes in structural integrity of platelets, decrease in pH, loss of aggregability, and kinetics in vivo of platelets tagged with 51Cr were used as indicators of the tolerance of platelets to storage. A platelet concentration of less than 2.5 x 10(6) per cu mm, a temperature of storage less than 24 C, and continuous, gentle, agitation were found to be essential for satisfactory preservation of platelet integrity, function, and post-transfusion survival. Platelets from female donors tolerated storage less well than did platelets from male donors, possibly because the lower hematocrit of blood collection from females resulted in greater initial acidity of the concentrate. A number of other variables analyzed appear to be of little or no consequence for successful platelet storage.
 ...
PMID:A study of variables affecting the quality of platelets stored at "room temperature". 0 Aug 23

Predictable hydrolysis of [3H]digoxin-12alpha occurred in vitro with incubation in HCl or gastric juice. Hydrolysis varied with pH, time, temperature and agitation. Digoxin, the bis- and mono-digitoxosides of digoxigenin and digoxigenin were separated by silica gel thin-layer chromatography using chloroform-ethyl acetate-glacial acetic acid (25:25:1 v/v) and were quantitated by liquid scintillation spectrometry. Hydrolysis with incubation at 37 degrees and pH 3 for 90 min was minimal, but increased with increasing acidity until greater than 70% was hydrolysed at pH 1-2 after 30 min and greater than 96% after 90 min incubation. At pH 0-9, 87% was hydrolysed after 30 min. In vitro hydrolysis in gastric fluid was slightly less than in HCl at the same pH. A volunteer was given 150 muCi[3H]digoxin-12alpha by nasogastric tube during a pentagastrin infusion when gastric pH was 0-94. He remained on his left side and samples were aspirated at intervals and immediately neutralized. Ethanol-chloroform 50-50 (v/v) extracts of the gastric fluid aspirated after 90 min and of all the urine specimens collected for 5 days were applied to a DEAE Sephadex LH-20 column. The radioactivity appeared in a single peak as digoxigenin in the 90 min gastric aspirate and in all urine specimens. Extensive intragastric hydrolysis of digoxin may occur under conditions of maximum acid output.
 ...
PMID:Hydrolysis of digoxin by acid. 1 78

The effect of food on the bioavailability of metronidazole from three commercial sugar-coated tablets varying markedly in drug dissolution behavior relative to pH was determined after oral administration in healthy male subjects with low gastric acidity. Four subjects, whose gastric acidities were evaluated as low (hypo- or anacidity) by using a non-intubation method (Gastrotest tablets administration method), received, in a cross-over fashion, a single 250 mg dose in sugar-coated tablet during periods of fasting and non-fasting. The tablet having the fastest and most pH-independent dissolution rate gave significantly higher Cmax and AUC0-32 than the other tablets having extremely slow dissolution at pH 5 or 7.2, when the drug was administered in the fasting state. However, there were no statistically significant differences in the above parameters among the tablets tested when they were administered postprandially. The improvement of the bioavailability of the tablets exhibiting poorer dissolution in the pH range of 5 to 7.2 is ascribed to suggestible vigorous agitation in the digestive tract stimulated by food intake.
 ...
PMID:Effect of food on bioavailability of metronidazole from sugar-coated tablets having different dissolution rates in subjects with low gastric acidity. 373 76

Apparent acidity constants obtained for various benzothiadiazine diuretics by semiaqueous potentiometric titrations gave satisfactory agreement with many values obtained by aqueous potentiometry. One suitable method for determining the acidity constants of sparingly soluble drugs, the solubility variation with pH technique, does not take into account instability problems. The preparation of decomposition products and the TLC analysis of sample solutions at various time intervals during solubility studies of methyclothiazide and bendroflumethiazide indicated that decomposition takes place during agitation and equilibration. This decomposition in buffers of pH 8 and higher was confirmed with the acidified p-dimethylaminobenzaldehyde test for primary aromatic amines.
 ...
PMID:Semiaqueous potentiometric determinations of apparent pKa1 values for benzothiadiazines and detection of decomposition during solubility variation with pH studies. 726

It is controversial as to whether debris from hydroxyapatite (HA)-coated implants jeopardizes the long-term success of total joint replacements. It has been hypothesized that liberated HA particles are engulfed by macrophages and through normal cellular digestion prevent osteolysis and third-body wear. HA particulates, however, have been observed at the interface and on polyethylene articulating surfaces. There is limited data demonstrating the ability of HA to dissolve at the acidity levels associated with macrophage organelle digestion. The objective of this study was to determine if particulate HA could dissolve at the pH levels found in macrophage organelles. Characterized HA particles were placed into buffered solutions corresponding to phagosomal organelle pH levels: cytoplasmic (pH 7), phagosomal (pH 6), and lysosomal (pH 5). Flasks were under continuous agitation in a shaker chamber at 37 degrees C. Calcium and phosphate ions were measured beyond the maximum life span of an activated macrophage. The data showed that calcium ions rose within the first 24 h and then remained constant throughout the experiment for all pH groups. Phosphate ion concentration showed a similar pattern at the lysosomal pH but remained undetected at the other organelle pH levels. The saturation point was highest at the lysosomal pH level and lowest at the cytoplasmic pH level. The results of this experiment leave the potential for HA particles to dissolve following macrophage digestion. However, caution must be exercised when interpreting the macrophage organelle digestion hypothesis; the size of the HA particle, the length of time required to completely dissolve the particle, and potential cellular toxicity all are factors that have yet to be determined before this hypothesis can be validated.
 ...
PMID:Dissolution of particulate hydroxyapatite in a macrophage organelle model. 951 Nov 4

To determine the usefulness of the monkey as an animal model, which can predict in vivo performance of humans, the major gastrointestinal physiological parameters of this animal were evaluated. The pH of gastric juice collected by a fiberscope from the stomach in fasted cynomolgus monkeys showed a high acidity level, which ranged from 1.2 to 4.3. The gastric emptying time of oral dosage forms (solution, granules and tablets) showed that the larger size dosage forms seemed to be emptied more slowly, and three dosage forms were prolonged by feeding. The gastrointestinal agitation intensity of monkeys was estimated using controlled-release tablets of acetoaminophen, which showed a slow erosion rate. The in vivo release amount-time profiles of the tablet in fasted monkeys corresponded to their in vitro profiles with paddle agitation conditions of between 10 rpm and 50 rpm of the paddle method; this result was smaller than in dogs (100 rpm) but equivalent to that in humans (10 rpm). Further, the small intestinal transit time (SITT), estimated using a double marker method, ranged from 2.2 to 4.2 h in the fasting state and from 2.2 to 3.2 h in the fed state; the SITT was not significantly delayed by feeding. Comparison with the published data about dogs and humans showed these gastrointestinal physiological parameters of monkeys to be more similar to those of humans. Consequently, it is assumed that the monkey is useful as an animal model for bioavailability studies of oral dosage forms.
 ...
PMID:Suitability of the cynomolgus monkey as an animal model for drug absorption studies of oral dosage forms from the viewpoint of gastrointestinal physiology. 1451 52

The purpose of this work was to optimize the beta-galactosidase production by Kluyveromyces lactis, applying the Surface Response Methodology (SRM) and using deproteinized whey as fermentation medium. An Orthogonal Central Compound Design (OCCD) was used without repetition, with four factors: temperature, pH, agitation speed and fermentation time. Then, enzyme activity (U/ml) as response variable was used. Thirty trials in twenty-five treatments, with six repetitions at the central point, were carried out, in a New Brunswick Bioflo 2000 fermentor with a volume of 2 liters. The deproteinized whey obtained by thermocoagulation was chemically analyzed. The results were: moisture 93.83%, total solids 6.17%, protein 0.44%, lactose 4.85%, acidity 0.43% and pH 4.58. The best conditions in the enzyme production were: temperature 30.3 degrees C, pH 4.68, agitation speed 191 r.p.m. and fermentation time 18.5 h. with an enzyme production of 8.3 U/ml. The degree of purification obtained was 7.4 times and the yield was 50.8%. The purified enzyme had an optimum temperature of 60 degrees C and a pH of 6.2. This work shows that the yeast Kluyveromyces lactis grown in deproteinized whey is able to produce the enzyme beta-galactosidase and SRM can be used in the fermentology processes, specifically in determining the best suitable operation conditions.
 ...
PMID:[Production and partial characterization of beta-galactosidase from Kluyveromyces lactis grown in deproteinized whey]. 1452 11

Under stationary and anaerobic conditions, greater cell yields of Lactobacillus brevis were obtained from autoclaved than from filter-sterilized glucose media. Fructose, tentatively identified as a product generated by the heating process, served as an excellent catalyst for inducing growth. The addition of micromolar quantities of pentoses or potential pentose precursors to the filter-sterilized medium was equally effective in stimulating growth. These organic catalysts were not essential for growth under aerobic conditions. Upon agitation, similar cell yields were obtained from the autoclaved and filter-sterilized media. The micromolar quantities of lactic acid produced per micromole of carbohydrate fermented appeared to be similar under aerobic and static conditions of incubation. The final concentration of acetic acid increased as the result of agitation. This increase in volatile acidity was accompanied by a significant decrease in ethyl alcohol production. The cell yield was increased nearly 50% under aerobic conditions.
 ...
PMID:Growth Response of Lactobacillus brevis to Aeration and Organic Catalysts. 1634 21

Toluene extraction was utilized to recover 2,4-dinitrotoluene (DNT), 2,6-DNT, and 2,4,6-trinitrotoluene (TNT) from wastewater of toluene nitration process. The batch-wise experiments were performed to elucidate the influence of various operating variables on the extracting behavior, including extracting temperature, volume ratios of solvent versus wastewater, agitation time, acidity of wastewater, and extraction stages. It was found that recovery of total organic compounds (TOC) was significantly elevated with increasing extraction temperature. Besides, high volume ratio of toluene/wastewater (2.0) and wastewater acidified to lower pH value enhanced the recovery percentage of TOC, in which extractable tendency was as follows: 2,6-DNT>2,4-DNT>2,4,6-TNT. It is worth noting that the nitrotoluenes in wastewater would be almost completely recovered using three sequential stages toluene extraction at the agitation time of 12min and pH 3.0. It is apparent that this established method is promising for the treatment of wastewater from toluene nitration processed industrially.
 ...
PMID:Recovery of nitrotoluenes in wastewater by solvent extraction. 1714 11

The effect of whey protein concentrate (WPC) and gum tragacanth (GT) as fat replacers on the chemical, physical, and microstructural properties of nonfat yogurt was investigated. The WPC (7.5, 15, and 20 g/L) and GT (0.25, 0.5, 0.75, and 1 g/L) were incorporated into the skim milk slowly at 40 to 45 degrees C with agitation. The yogurt mixes were pasteurized at 90 degrees C for 10 min, inoculated with 0.1% starter culture, and incubated at 42 degrees C to pH 4.6, then refrigerated overnight at 5 degrees C. A control nonfat yogurt and control full fat yogurt were prepared as described, but without addition of WPC and GT. Increasing amount of WPC led to the increase in total solids, total protein, acidity, and ash content, whereas GT did not affect chemical parameters. Increasing WPC caused a more compact structure consisting of robust casein particles and large aggregates. Firmness was increased and susceptibility to syneresis was decreased as WPC increased. No significant difference was observed for firmness and syneresis of yogurt fortified with GT up to 0.5 g/L compared with control nonfat yogurt. Increasing the amount of gum above 0.5 g/L produced softer gels with a greater tendency for syneresis than the ones prepared without it. Addition of GT led to the coarser and more open structure compared with control yogurt.
 ...
PMID:Whey protein concentrate and gum tragacanth as fat replacers in nonfat yogurt: chemical, physical, and microstructural properties. 1856 11


1 2 Next >>