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

The effect of gastric pH on the viability and virulence of Yersinia enterocolitica O:8 after exposure to sublethal concentrations of copper and chlorine was determined in mice. Viability and injury were assessed with a nonselective TLY agar (tryptic soy broth containing lactose, yeast extract, and agar) and two selective media, TLYD agar (TLY agar plus sodium deoxycholate) and CIN agar (cefsulodin-Irgasan-novobiocin agar). Both copper and chlorine caused injury which was manifested by the inability of the cells to grow on selective media. CIN agar was more restrictive to the growth of injured cells than TLYD agar. Injury of the exposed cells was further enhanced in the gastric environment of mice. Besides injury, the low gastric pH caused extensive loss of viability in copper-exposed cells. Lethality in the chlorine-exposed cells was less extensive, and a portion of the inoculum (5.2 X 10(5) of 1 X 10(7) inoculated cells) reached the small intestine 5 min postinoculation. No adverse effect on the injured cells was apparent in the small intestine, and a substantial revival (approximately 70%) of the injury occurred in 3 to 4 h after intraluminal inoculation. The virulence of chlorine-stressed Y. enterocolitica in orally inoculated mice was similar to that of the control culture, but copper-stressed cells showed reduced virulence. Virulence was partly restored by oral administration of sodium bicarbonate before the inoculation of copper-exposed cells. Neutralization of gastric acidity had no effect on the virulence of the control or chlorine-stressed cells. The results of this study indicate that the extensive injury caused by the low gastric pH does not affect the virulence potential of chlorine-exposed cells. However, extensive cell death in the mouse stomach is responsible for the reduced virulence of the copper-stressed bacteria.
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PMID:Survival and virulence of copper- and chlorine-stressed Yersinia enterocolitica in experimentally infected mice. 366 14

The concentration dependence of the chemical shifts of the protons H-2, H-8, H-10, H-11, and H-1' of 1,N6-ethenoadenosine 5'-monophosphate (epsilon-AMP2-) has been measured. The results are consistent with the isodesmic model of indefinite noncooperative stacking; the association constant, K = 2.5 +/- 0.3 M-1, is within experimental error identical to the value determined earlier for AMP2-,K = 2.1 +/- 0.4 M-1. The conditions for the potentiometric pH titrations, used to determine the acidity constants of H2(epsilon-AMP), H2(AMP), and H(UMP)- and the stability constants of the metal ion (M2+) complexes of the corresponding nucleoside 5'-monophosphates (NMP), were chosen so that the ligands were present in the monomeric form. The stabilities of Mg(epsilon-AMP) and Mg(AMP) are similar; however, the stabilities of the Mn2+, Cu2+ and Zn2+ complexes of epsilon-AMP2- are much larger (in the case of Cu2+ by a factor of 700) than those of AMP2-. This is due to the much larger metal ion affinity of the epsilon-adenosine moiety compared to that of the parent adenosine residue. As the uridine moiety does not participate in complex formation, the stability constants of M(UMP) have been used to evaluate the extent of macrochelation (i.e. the simultaneous coordination of M2+ to the base moiety and the phosphate group) in the epsilon-AMP and AMP complexes: the concentration of the macrochelated isomer is considerably larger for M(epsilon-AMP) than for M(AMP). A comparison with previous results for the complexes with ADP3- and ATP4- indicates the order, M(AMP)cl less than M(ADP)-cl greater than M(ATP)2-cl for the tendency to form macrochelates (cl). Due to the relatively high affinity of the epsilon-adenosine moiety towards Mn2+, Cu2+ and Zn2+, the phosphate-monoprotonated complexes M(H . epsilon-AMP)+ also become important; the corresponding complexes play only a minor role in the M2+/AMP systems. Intramolecular aromatic-ring stacking occurs in the ternary Cu(2,2'-bipyridyl)(NMP) complexes: about 80% of Cu(Bpy)(AMP) and Cu(Bpy)(epsilon-AMP) exist as the stacked isomer in aqueous solution; for the former system it has been shown in a previous X-ray study that the intramolecular ligand-ligand interaction occurs also in the solid state [Aoki, K. (1978) J. Am. Chem. Soc. 100, 7106]. Overall, the results emphasize that great care should be exercised in drawing conclusions based on studies of metal-ion-containing enzymic systems in which the natural adenine nucleotide cofactors have been replaced by the corresponding 1,N6-etheno derivatives.
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PMID:On the metal-ion coordinating properties of the 5'-monophosphates of 1, N6-ethenoadenosine (epsilon-AMP), adenosine and uridine. Comparison of the macrochelate formation in the complexes of epsilon-AMP, AMP, ADP and ATP. 632 Nov 71

The process of sperm transport is followed from ejaculate, through deposition in the vagina, into the oviducts where fertilization occurs. The cyclic influence of the sex hormones, governed by the female menstrual cycle, causes characteristic changes in the entire genital tract, resulting in different secretions, some of which are more favorable to the survival of sperm in their transport through the female genital tract. The level of acidity in the vagina can be influenced by sexual behavior and by secretions of the upper genital tract. A sufficient glucose content in the cervical mucus is essential for sperm survival. A literature review presents what has been learned regarding sperm transport from various recent studies. Transport at different times is seen to be both active and passive. Infertility studies have contributed to current knowledge regarding sperm transport and capacitation. The IUD seems to effect biochemical, biophysical, cytological, and histological changes in the epithelia and their fluids. In fact, the different types of IUDs exert differing antifertility effects. Inert IUDs seem to create disturbances in the endometrium, preventing implantation. Copper-bearing and medicated IUDs exert influences in addition to the foreign-body reaction. In fact, some of these IUDs cause changes in the entire genital tract.
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PMID:Sperm migration in the human female genital tract with and without intrauterine devices. 700 46

Copper complexes of phenols related to salicylic acid were prepared in DMSO and applied to the shaved dorsal skin of rats. The following activities were assayed: (i) suppression of the carrageenan or hydroxylapatite paw oedemas; (ii) reduction of chronic inflammation in established adjuvant arthritis; (iii) local skin toxicity. Cu(II) was an essential component. Some limited structure-activity correlations were made among alternative cupriphores. DMSO solutions of copper complexes were more potent than their solutions in ethanol. Glycerol was a beneficial additive. Reducing the acidity of some copper salicylate formulations also reduced their potency. Niflumic acid and phenylbutazone were effective non-salicylate transcutaneous cupriphores.
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PMID:Lipophilic copper(II) formulations: some correlations between their composition and anti-inflammatory/anti-arthritic activity when applied to the skin of rats. 708 Sep 60

The acidity constant of protonated 2-[bis(2-hydroxyethyl)amino]-2(hydroxymethyl)-1,3-propanediol (Bistris) has been measured. The influence of hydroxo groups on the basicity of Bistris and related bases is discussed. The interaction of Bistris with the metal ions (M2+) Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, and Pb2+ was studied by potentiometry and spectrophotometry in aqueous solution (I = 1.0 M, KNO3; 25 degrees C) and the stability constants of the M(Bistris)2+ complexes were determined. Unexpectedly Ca(Bistris)2+ is the most stable among the alkaline earth ion complexes (log KCaCa(Bistris) = 2.25; the corresponding values for the Mg2+, Sr2+ and Ba2+ complexes are 0.34, 1.44 and 0.85, respectively). The ions of the 3d series follow the Irving-Williams sequence: log KMnMn(Bistris) = 0.70, for Cu2+, 5.27 and Zn2+ 2.38. Ternary complexes containing ATP4- as a second ligand were also investigated: the values for delta log KM (= log KM(ATP)M(ATP)(Bistris) -log KMM(Bistris) are in general negative (e.g. delta log KCa = -0.40 or delta log KCu = -1.65), thus indicating that the interaction of Bistris with M(ATP)2- is somewhat less pronounced tan with M2+. However, even in mixed-ligand systems, complex formation may still be considerable, hence great reservations should be exercised in employing Bistris as a buffer in systems containing metal ions. Moreover, in several cases delta log KM is relatively high [for Mg2+-ATP4- -Bistris even positive], indicating some cooperativity between the coordinated ligands, possibly hydrogen-bond formation. Distributions of the complexes in dependence on pH are given, and the structures of the binary M(Bistris)2+ and the ternary M(ATP) (Bistris)2- complexes are discussed. The participation of Bistris hydroxo groups in complex formation is evident.
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PMID:Metal ion/buffer interactions. Stability of binary and ternary complexes containing 2-[bis(2-hydroxyethyl)amino]-2(hydroxymethyl)-1,3-propanediol (Bistris) and adenosine 5'-triphosphate (ATP). 739 53

WIN 22169 is a co-polymer containing approximately 11 repeating units of polyoxyethylene and diethylenetriamine pentaacetic acid (DTPA). WIN 66368, a magnetic resonance imaging (MRI) contrast agent, is the gadolinium III complex of WIN 22169. WIN 22169 has been characterized with respect to its equivalent weight, acidity constants and excess acid or base, as well as its metal ion binding constants. The logs of the equilibrium binding constants of the ligand to Gd3+, Ca2+, Zn2+ and Cu2+ were found to be 16.6, 7.47, 12.2 and 14.0. The Gd selectivity constant, a measure of the preferential binding of the ligand toward Gd3+ versus the three in vivo ions: Ca2+, Zn2+ and Cu2+, of WIN 66368 was calculated to be 7.9. This value compares favourably to that for Gd DTPA which has a Gd selectivity constant of 7.04.
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PMID:Binding constant determination of WIN 22169, a novel polymeric ligand. 781 75

From a population of 8918 farmers, 237 were selected whose consumption of locally produced foods was high. The subjects' water sources, private wells, were of different degrees of acidity. Significant associations between pH (median 6.7, range 4.7-8.6) of the drinking water and element concentrations were found. The correlation was negative for aluminium (Al; median 0.07 mumol/l), cadmium (Cd; 0.44 nmol/l), copper (Cu; 0.24 mumol/l) and lead (Pb; 1.9 nmol/l), and positive for calcium (Ca; 0.62 mmol/l) and magnesium (Mg; 0.21 mmol/l). Associations could not be found between the pH of, or element concentrations in, the water and concentrations of A1 (0.17 mumol/l), Mg (0.86 mmol/l) and selenium (Se; 1.0 mumol/l) in plasma, Cd (2.0 nmol/l), Pb (0.19 mumol/l) and mercury (Hg; 13 nmol/l) in blood, or A1 (12 mumol/mol creatinine) and Cu (11 mumol/mol creatinine) in urine. The concentrations of Hg in blood and Se in plasma were related to fish consumption, Cd and Pb in blood to smoking, A1 in urine to antacid intake, Pb in blood to rifle activities and hunting, and Hg in blood to hunting. Acid precipitation has an effect on element concentrations in drinking water, but not on the retention of those elements in the subjects investigated.
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PMID:Effect of acid precipitation on retention and excretion of elements in man. 801 32

Anhydrotetracycline (AHTC), one of the major toxic decomposition products of the antibiotic tetracycline, contains several potential binding sites to metal ions. The acidity constants of the ligand were calculated in aqueous medium (I = 0.1 M) at 25 and 37 degrees C. We found pKa1 = 3.23 +/- 0.08, pKa2 = 5.94 +/- 0.09, and pKa3 = 8.48 +/- 0.02 at 25 degrees C and pKa1 = 3.12 +/- 0.09, pKa2 = 5.86 +/- 0.03, and pKa3 = 8.38 +/- 0.04 at 37 degrees C. The coordination of AHTC to Cu(II) and Ni(II) ions was studied in the solid state as well as in buffered aqueous solution at pH 10.0. At this pH, the formation of the two CuL2 and CuL species was indicated (log beta 1 = 8.41 +/- 0.04 and log beta 2 = 12.55 +/- 0.05), but only the formation of the NiL complex (log beta = 5.74 +/- 0.04) was identified. Spectroscopic data confirm the previous assignment of the C11 and C12 oxygens as the coordination sites, yielding six-membered ring chelates and excluding complexation through any of the potential binding positions on ring A.
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PMID:Metal complexes of anhydrotetracycline. 1. A spectrometric study of the Cu(II) and Ni(II) complexes. 820 70

EC50s for cadmium, copper, lead and zinc were determined for juvenile production of Folsomia candida at pH6.0, 5.0 and 4.5 in a standard laboratory test system. In contrast to most previous studies where metal toxicity was increased at low pHs, in our experiments there was no clear relationship between soil acidity and EC50-reproduction in this species. The EC50-reproduction values (microgram g-1) for cadmium and zinc were similar at all three pHs (pH6.0: Cd 590, Zn 900; pH5.0: Cd 780, Zn 600; pH4.5: Cd 480, Zn 590). In contaminated field sites adjacent to primary zinc smelters, zinc is invariably present in soils at concentrations of at least 50 times that of cadmium. Thus deleterious effects of mixtures of these metals on populations of Collembola in such sites can be attributed to zinc rather than cadmium.
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PMID:Effects of pH on the toxicity of cadmium, copper, lead and zinc to Folsomia candida Willem, 1902 (Collembola) in a standard laboratory test system. 897 58

The oxidation of low density lipoprotein (LDL) within atherosclerotic lesions may be involved in atherogenesis. LDL oxidation by cells in the presence of iron is faster at acidic pH. In addition, LDL oxidation by iron alone or iron cysteine in the absence of cells is much faster at acidic pH, even at mildly acidic pH (pH 6.5). The effect of pH on LDL oxidation by copper ions is more complex, in that acidity slows down the initial oxidation, as measured by conjugated dienes, hydroperoxides and thiobarbituric acid-reactive substances, but can increase the later stages of LDL oxidation as measured by increased macrophage uptake. Extensive LDL oxidation by cells in atherosclerotic lesions probably requires a source of iron or copper as catalysts for the oxidation. Iron in plasma is carried by the protein transferrin. Lowering the pH releases some of the iron from transferrin so that it can catalyse LDL oxidation. Copper is carried in plasma on caeruloplasmin and becomes more effective in catalysing LDL oxidation when the caeruloplasmin is preincubated at acidic pH, or even at pH 7.0. These effects can be seen with concentrations of caeruloplasmin and transferrin below those present in plasma. By analogy to other inflammatory and ischaemic sites, atherosclerotic lesions may well have an acidic extracellular pH, particularly within clusters of macrophages where the oxidative stress may also be high. This localised acidic pH may help to explain why atherosclerotic lesions are one of the few sites in the body where extensive LDL oxidation occurs.
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PMID:Does an acidic pH explain why low density lipoprotein is oxidised in atherosclerotic lesions? 910 56


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