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)

Laban had a titratable acidity of about 1.0%, a pH of 4.25, an ethanol content of 1.25%, and contained 4.2 mug acetaldehyde and 34 mug acetoin/ml. There was no diacetyl. Five microorganisms, classified as Streptococcus thermophilus, Lactobacillus acidophilus, Leuconostoc lactis, Kluyveromyces fragilis, and Saccharomyces cerevisiae, were responsible for the fermentation. Streptococcus thermophilus and L. acidophilus were responsible for acid production with S. thermophilus producing acid more rapidly. Most of the acetaldehyde was produced by K. fragilis, little ethanol was found in absence of S. cerevisiae, and the acetoin was producted by S. thermophilus.
 ...
PMID:Microorganisms and characteristics of laban. 0 30

Carbon 13 NMR spectra have been obtained for aqueous solutions of DL-2-(alpha-hydroxyethyl)thiamin, DL-2-(alpha-hydroxybenzyl)thiamin, DL-2-(alpha-hydroxybenzyl)oxythiamin, and related N-3 methyl and N-3 benzyl analogs. The unusually large downfield shift of the 13C resonance of C-2 of hydroxyethylthiamin suggests that this carbon bears a partial positive charge. This result stands in contrast to results of x-ray crystallographic studies of hydroxyethylthiamin, which place a partial negative charge on C-2 (Pletcher, J., and Sax, M. (1974) J. Am. Chem. Soc. 96, 155-165). A partial positive charge on C-2 helps to explain the facility of carbanion formation at the alpha carbon both enzymatically and in model systems. The rates of proton-deuteron exchange of (C-alpha)-H with solvent deuterium, and of release of aldehyde to regenerate thiamin have been measured for hydroxyethylthiamin and analogs. The differences in kinetic acidity of (C-alpha)-H and of rates of aldehyde release are rationalized in terms of differing electron-withdrawing abilities of the substituents attached to N-3, and appear not to be related to intramolecular basic catalysis of these processes by the C-4' amino group.
 ...
PMID:Carbon 13 magnetic resonance studies of DL-2-(alpha-hydroxyethyl) thiamin and related compounds. Relation of kinetic acidity to electronic factors in thiamin catalysis. 0 50

The duodenal glands of cat and horse were studied using PAS, Alcian blue, dialysed iron, aldehyde fuchsin-Alcian blue and high iron diamine stains. It was found that the duodenal glands of the horse reacted positively to Alcian blue, dialysed iron stains and also took the Alcian blue stain in the combined aldehyde fuchsin-Alcian blue and high iron diamine-Alcian blue stains. Those of the cat gave negative results. These results suggest the presence of acidic groups in the mucosubstances secreted by the horse's duodenal glands. A suggestion is put forward on the strength of the high iron diamine-Alcian blue combined stains that the acidity is due to the presence of carboxyl groups. It is suggested that the acidity may be significant in either cellulose metabolism or the digestion of the bacterial microflora from the stomach of herbivores.
 ...
PMID:Histochemistry of the duodenal glands of the cat and horse. 7 85

The effects of fermentation of aqueous extracts of peanuts (peanut milk) with Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus salivarius ssp. thermophilus, separately and in combination, on selected chemical and sensory qualities were investigated. Changes in pH, titratable acidity and viable cell populations indicated that there was a synergistic interaction between L. delbrueckii ssp. bulgaricus and S. salivarius ssp. thermophilus during fermentation. Analysis of headspace volatiles revealed that hexanal, which is one of the compounds responsible for undesirable green/beany flavor in peanut milk, completely disappeared as a result of fermentation. S. salivarius ssp. thermophilus was more effective than L. delbrueckii ssp. bulgaricus in reducing the hexanal content. The acetaldehyde content of peanut milk increased during fermentation. Changes in concentrations of these volatile compounds were correlated with sensory evaluation scores which showed that a significant (P less than or equal to 0.05) decrease in green/beany flavor and a significant increase in creamy flavor occurred as a result of fermentation.
 ...
PMID:Changes in chemical composition and sensory qualities of peanut milk fermented with lactic acid bacteria. 191 Oct 84

To evaluate the combined effects of threonine and glycine concentrations during growth on threonine aldolase activity (EC 2.1.2.1) of yogurt microorganisms, Streptococcus thermophilus and Lactobacillus bulgaricus, a modified milk growth medium was prepared using UF to deplete the free amino acid level. Threonine and glycine were added according to a 2x2x2 factorial design at 5 or 195 microg.ml(-1) along with a standard amino acid mixture. Acetaldehyde production and threonine aldolase activity were evaluated utilizing headspace gas chromatography. Results showed that threonine and glycine concentrations did not affect growth or titratable acidity. The high concentration of threonine in combination with low glycine in the growth medium resulted in increased acetaldehyde synthesis by both microorganisms. Conversely, high glycine with low threonine decreased acetaldehyde synthesis. High threonine and low glycine increased threonine aldolase activity of cell-free extracts from S. thermophilus and L. bulgaricus, whereas high glycine and low threonine reduced threonine aldolase activity of both microorganisms.
 ...
PMID:Effect of threonine and glycine concentrations on threonine aldolase activity of yogurt microorganisms during growth in a modified milk prepared by ultrafiltration. 250 66

Acetaldehyde reacted with hemoglobin at neutral pH and 37 degrees C to form adducts that were stable to dialysis and that were not reduced by sodium borohydride. Hemoglobin tetramers having 2, 3, and probably 4 molar eq of bound aldehyde were isolated by cation exchange chromatography. The sites of attachment of the aldehyde were the free amino groups of the N-terminal valine residues of the alpha and beta chains of hemoglobin. Derivatization of the beta chains caused a greater increase in the acidity of the hemoglobin than did derivatization of the alpha chains. Derivatization of the beta chains was also preferred over that of the alpha chains. Acetaldehyde derivatives of the N-terminal octapeptide of hemoglobin S (beta sT-1 peptide), Val-Gly-Gly, and tetraglycine were formed readily, contained 1 M eq of acetaldehyde/mol of peptide, and were not reduced by sodium borohydride. In contrast, Ala-Pro-Gly failed to form a 1:1 adduct with acetaldehyde. 13C NMR analysis of the peptide adducts formed with [1,2-13C]acetaldehyde indicated that tetrahedral diastereomeric derivatives were produced. The 13C chemical shifts of the adducts formed between hemoglobin and [1,2-13C]acetaldehyde were identical to those of the peptide adducts although resonances from the individual diastereomeric adducts at each hemoglobin site could not be resolved. The results cited above as well as other evidence indicate that acetaldehyde reacts with the amino termini of hemoglobin to form stable cyclic imidazolidinone derivatives. An exchange of acetaldehyde residues between peptides was also documented.
 ...
PMID:Reaction of acetaldehyde with hemoglobin. 370 Apr 16

Studied were the changes setting in with fats in the process of ripening of the ewe milk yellow cheese, kashkaval type, and cow milk yellow cheese Vitosha treated with the antimold preparations 'antiplessin' and 'potassium sorbate with movilit'. There were slightly expressed hydrolytic and oxidation processes involving the milk fat. On the 60th day fat acidity after Ketstorfer was 2.17 degrees K, resp., 2.25 degrees K, on an average, with ewe milk kashkaval, and 1.92 degrees K, resp., 2.03 degrees C, on an average, with Vitosha cheese. On the 60th day of ripening the peroxide number of milk fat in kashkaval was 0.1316, resp., 0.1335, on an average, and in Vitosha cheese it was within the range of 1.0298 to 0.1454, on an average. The average values of the iodine number of fats dropped up to the 60th day, however, remained within the normal value characteristic of quality fats.--32.77, resp., 32.97 for kashkaval, and 31.40, resp., 29.30 for cheese Vitosha. No epihydrin aldehyde was found in both types of cheese up to the 60th day of ripening with the use of the two preparations.
 ...
PMID:[Changes in the fats in yellow cheese treated with surface antimold agents]. 716 38

To ascertain whether any of the well-known effects of intravenous ethanol on pancreatic and gastric secretion could be due to its metabolite--acetaldehyde, a strong cytotoxic and sympathomimetic agent--acetaldehyde was given intravenously for 1 h (50, 100, and 200 mg/kg/h) in seven dogs. Acetaldehyde did not modify pancreatic secretion stimulated with secretin and caerulein, but under basal conditions 200 mg/kg/h slightly increased the volume and protein content of pancreatic juice. Acetaldehyde increased gastric secretion up to 4.03 meq/15 min in a dose-dependent manner, while serum gastrin remained unchanged. The increase of acidity persisted after propranolol and was inhibited but not abolished by ganglionic blockade. It can be concluded that physiological concentrations of acetaldehyde do not interfere with pancreatic secretion and that it is possible that the stimulatory effect of ethanol on gastric secretion is mediated at least partly through acetaldehyde.
 ...
PMID:The effect of acetaldehyde on pancreatic and gastric secretion. 720 90

The sensory properties of traditional acidic and mild, less acidic yogurts were characterized by a trained panel using a descriptive approach. Many of the descriptive attributes varied almost linearly with pH, showing either a positive or negative correlation with increasing acidity. The panel was very sensitive to acidity differences, as demonstrated by the linear relationship between acidity perception and pH. Important flavor differences were found between the two classes of yogurt. They were mainly due to differences in acidity and not to different concentrations of the three impact aroma compounds, acetaldehyde, 2,3-butanedione, and 2, 3-pentanedione. This emphasizes the importance of acidity in yogurt flavor. Deodorization and impact aroma compound addition had much less influence on yogurt flavor than pH variations.
 ...
PMID:Sensory investigation of yogurt flavor perception: mutual influence of volatiles and acidity. 1069 54

Astrocytes are known to play a key role in buffering extracellular pH variations and, in addition, they are particularly resistant to oxidative stress and subsequent lipid peroxidation. This great resistance may be ascribed to the presence of high concentrations of certain antioxidants, but another explanation may be the presence of a high quantity of plasmalogens, which are a special group of glycerophospholipids characterized by a vinyl ether bond instead of an ester bond in the sn-1 position of the glycerol backbone. Plasmalogens are sensitive to free radical attack and acidity, and numerous works have supported the hypothesis that they may be antioxidant molecules that protect cells from oxidative stress. The aim of this work was to investigate, on astrocytes in lactic acid-induced oxidative stress (pH 5.5), the behavior of phospholipids and, in particular, plasmalogens. Two main techniques, based on the susceptibility of the vinyl ether bond to hydrolysis, were employed in this study to measure plasmalogen levels. In both cases, the sn-1 vinyl ether linkage was cleaved using mercuric chloride, producing a lysophospholipid that was assessed by phosphorus measurement or using HCl treatment, producing a long-chain fatty aldehyde assayed by gas chromatography/mass spectrometry. On astrocytes in culture, only plasmenylethanolamine (PlmEtn) was evidenced, representing 40% of glycerophosphoethanolamine lipids. When astrocytes were incubated with lactic acid, no modification in the amount of PlmEtn was seen. Furthermore, free aldehydes and aldehydes corresponding to the quantity of intact plasmalogens were similar to those observed on controls. In addition, the constancy of two lipid peroxidation markers, thiobarbituric acid reactive substances and polyunsaturated fatty acids, was clear evidence of the resistance of these cells in lactic acid conditions. In conclusion, our results fail to demonstrate a major role of plasmalogens in the resistance of astrocytes in lactic acid-induced oxidative stress.
 ...
PMID:Evidence against a major role of plasmalogens in the resistance of astrocytes in lactic acid-induced oxidative stress in vitro. 1121 46


1 2 3 4 5 6 7 8 9 10 Next >>