Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0009443 (cold)
 92,137 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Activities of acid phosphatase, beta-glucuronidase, N-acethyl-beta-D-glucosaminidase and acid beta-galactosidase were investigated histochemically in rabbit corneas. Frozen sections after block fixation in cold 4% formaldehyde with 1% CaCl2 followed by washing in cold physiological saline as well as cold microtome sections of corneas quenched in petroleter chilled with acetone-dry ice mixture, transferred to nonprecooled slides or semipermeable membranes were used. Standard aqueous media were employed in the case of free-floating frozen sections of fixed corneas as well as of cold mictrotome sections (postfixed in cold 4% formaldehyde). Agar media were used in connection with the technic of semipermeable membranes. Gomori method (in the case of acid phosphatase), simultaneous azocoupling methods (substrates derivated of naphthol-AS-BI with hexazonium-p-rosanilin) in the case of acid phosphatase, beta-glucuronidase and N-acetyl-beta-D-glucosaminidase and the indigogenic method in the case of acid beta-galactosidase were applied. Enzyme activities in sections of fixed corneas were minimal in comparison with those in cold microtome sections of unfixed material revealed particularly with the technic of semipermeable membranes which is to be preferred. This technic is recommended in studies concerned with lysosomal enzymes in the cornea, particularly in keratocytes. All enzymes investigated were present in corneal epithelium, keratocytes and endothelium. Acid phosphatase displayed the highest activity followed by beta-glucuronidase and acetyl-beta-D-glucosaminidase. The activity of beta-galactosidase was the lowest. For the demonstration of activities in keratocytes sections parallel to the surface are very suitable. In these sections enzyme activities were demonstrated in small granules (apparently lysosomes) present in the central part of their cytoplasm as well as in projections. Diffuse staining was also seen, being the highest in the case of acid phosphatase.
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PMID:Distribution of acid phosphatase, beta-glucuronidase, n-acetyl-beta-d-glucosaminidase and beta-galactosidase in cornea of albino rabbit. 5 44

A partially purified soluble ATPase (ATP phosphohydrolase, EC 3.6.1.3) from pea cotyledon mitochondria was characterized. Inhibition patterns with azide, NaF, and cold, and a stimulation by 2,4-dinitrophenol were typical of F1-ATPases from mammalian mitochondria. The enzyme hydrolysed GTP, ITP, and ATP, but not CTP, UTP, ADP, or IDP. ATPase and ITPase activities were strongly inhibited by ADP and to a lesser extent by IDP. Distinctive properties of the pea mitochondrial enzyme were activation by high concentrations of CaCl2 and stimulation by NaCl.
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PMID:Partial characterization of a soluble ATPase from pea cotyledon mitochondria. 14 76

The course of polymerization of individual brain microtubules could be observed with a light microscope employing dark-field illumination. Statistical analysis of the increase in microtubule length during the polymerization was in accordance with the time course of viscosity change of the tubulin solution. After a plateau level in viscosity was attained, there was no significant change in histograms showing length distribution. These observations were confirmed with fixed and stained microtubules, using a phase-contrast microscope. Observations with dark-field illumination revealed that reconstituted microtubules depolymerized and disappeared immediately upon exposure to buffer containing CaCl2 or sulphydryl reagents such as p-chloromercuriphenyl sulphonic acid (PCMPS) and p-chloromercuribenzoic acid (PCMB). They were also cold-labile. The growth of heterogeneous microtubules which were assembled by mixing purified tubulin dimers with ciliary outer fibres could also be followed with these optical systems.
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PMID:Light-microscopic observations of individual microtubules reconstituted from brain tubulin. 17 26

Escherichia coli cells prepared for transformation by treatment with cold 0.1 M CaCl2 remained viable and competent after storage at -82 degrees C in 15% glycerol; thawed-cell samples yielded up to 10(6) transformants per microgram of plasmid deoxyribonucleic acid.
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PMID:Transformation in Escherichia coli: cryogenic preservation of competent cells. 33 31

The susceptibility of E. coli strain chi1776 to transformation by pBR322 plasmid DNA was examined and optimized. Maximum transformation to tetracycline (Tc) resistance was achieved when cells were harvested from L broth at 5.0--6.0 . 10(7) cfu/ml, followed by washing twice in cold 0.1 M NaCl + 5 mM MgCl2 + 5 mM Tris, pH 7.6. Cells grown in the presence of D-cycloserine (Cyc) rather than nalidixic acid (Nx) transformed markedly better. The presence of 5 mM Mg2+ ions in washing and CaCl2 solutions stimulated transformation about 2-fold. Optimal conditions for transformation included a pH range of 7.25-7.75 and a cell-to-DNA ratio of about 1.6 . 10(8) cfu/ng plasmid DNA. The frequency of transformation was highest when cells were exposed to 100 mM CaCl2 in 250 mM KCl + 5 mM MgCl2 + 5 mM Tris, pH 7.6, before mixing with DNA. A 60 min incubation period for cell + DNA mixtures held on ice produced the maximum number of Tcr transformants. In our hands, heat shocks at 37 degrees C or 42 degrees C for various times all decreased transformation to about one-half of optimal levels. Furthermore, the recovery of transformants was best when cell + DNA mixtures were plated on precooled (4 degrees C) Tc agar plates. The efficiency of plating was optimum when only 5 microliter of cell + DNA mixture was spread per plate, suggesting that non-viable background chi1776 cells on selective medium inhibited the recovery of transformants. It was also found that the presence of linear DNA molecules in cell + DNA mixtures markedly inhibited the transformation of chi1776 by pBR322 plasmid DNA. On the basis of these findings, a new procedure for the plasmid-specific transformation of E. coli chi1776 by pBR322 plasmid DNA is proposed. The use of this technique has allowed us to attain transformation frequencies in excess of 10(7) transformants/microgram pBR322 plasmid DNA.
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PMID:Factors affecting the transformation of Escherichia coli strain chi1776 by pBR322 plasmid DNA. 36 84

Plasmolysed cells of Escherichia coli N212 (uvr A recA) acquired ultraviolet resistance when the cells were exposed to high concentrations of T4 endonuclease V. With increasing concentrations of T4 enzyme, survivals of plasmolysed cells after ultraviolet irradiation increased while colony-forming ability of unirradiated plasmolysed cells was not significantly affected by the enzyme treatment. Under appropriate conditions more than 200 fold increase in survivals was observed. When plasmolysed cells were treated with a pre-heated enzyme preparation or enzyme fractions derived from T4v1 (endonuclease V-deficient mutant)-infected cells, only little or no reactivation took place. Permeabilization of cells prior to the enzyme treatment was essential for the effective reactivation. Treatment of intact cells with the T4 enzyme did not cause any reactivation. Cells treated with 20 mM EGTA or 50 mM CaCl2 in cold were reactivated to certain extents by the enzyme, but the extents of the reactivation were far less compared to those of plasmolysed cells. Plasmolysed cells of strains carrying a mutation in one of uvrA, uvrB and uvrC genes were reactivated by introduction of T4 endonuclease V, as was the uvrA recA double mutant. UvrD mutants were also reactivated, but rather slightly. However, wild type strain as well as strains having a mutation in recA or polA gene were not reactivated. From these results it was suggested that T4 endonuclease V, taken up into permeable cells, can function in vivo to replace defective functions, which are controlled by the uvr genes. The conditions established in the present study may be used for introduction of other proteins into viable bacterial cells.
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PMID:Introduction of an active enzyme into permeable cells of Escherichia coli: acquisition of ultraviolet light resistance by uvr mutants on introduction of T4 endonuclease V. 37 39

Actin transferred to concentrated (0.3-1.2 M) MgCl2 solutions depolymerizes completely. When protected by a high excess of ATP, actin in this MgCl2-depolymerized state is stable for several days in the cold. In the absence of excess ATP it slowly denatures. Chiroptical data and proteolysis experiments show that MgCl2-depolymerized actin is in a native, folded state, although its helix content is considerably decreased. By dissolving F-actin pellets or actin precipitated in paracrystalline state in concentrated MgCl2 solutions in the presence of ATP, very concentrated (100-200 mg/ml) monomeric actin solutions can be prepared. CaCl2 and MnCl2 have similar effects although these were not studied in detail.
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PMID:Depolymerization of actin in concentrated solutions of divalent metal chlorides. 51 8

The competence formation in 2 strains of Escherichia coli X7026 and Hfr H to isolated phage gamma DNA after the prolonged treatment of cells with Ca++ ions at low temperatures was investigated. In both strains studied the sensitivity of cells to phage lambda DNA increased during several days of maintenance at 4 degrees C in 0.2 M CaCl2, and reached the maximal value in 24-48 hours for E. coli Hfr H cells, and in 72-96 hours for E. coli X7026 cells. Cells maintained in CaCl2 for 24 hours and more interacted more effectively with DNA in the cold, and didn't need Ca++ ions at the last stage of transfection (incubation of the infectious mixture at 37 degrees C) as the freshly grown cells did. Variations induced in the cells after the prolonged action Ca++ ions were preserved only in the presence of CaCl2. After the washing of CaCl2 from the cells with 0.15 M NaCl they returned to the initial state. The competence formation in cells of E. coli X7026 under the effect of Ca++ ions was going on more actively when the cells were preliminary incubated for several days at 4 degrees C in the absence of CaCl2. E. coli Hfr H cells were resistant to this treatment.
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PMID:[Competence in Escherichia coli cells. III. Formation of competent states in Escherichia coli X7026 and Escherichia coli Hfr H cells during storage in different conditions]. 76 99

The resistance of brain 32S tubulin oligomer to factors suppressing the microtubules formation: colchicine, CaCl2, cooling and the absence of GTP is studied. The content of oligomer in the preparation and the polymerization degree were estimated by means of analytical centrifugation. Colchicine at 25 degrees and at a concentration of 10 muM does not change and at a concentration of 100 muM only slightly decreases the content of oligomer. The oligomer dissociated (but not completely) in 1 mM colchicine. Tubulin polymerization was partly suppressed by 10 muM and completely--by 100 muM colchicine. CaCl2 at 1 and 10 mM concentrations did not destroy the oligomer but inhibited its polymerization even in lesser of these concentrations. The cooling of the incubation medium to 14 degrees C or 4 degrees C completely inhibited the polymerization and did not affect the content of oligomer in the preparations. Tbulin preparations with low amount of exogenous GTP (less than or equal 3.10(-6) M) had a usual oligomer content, whereas GTP is necessary for polymerization at concentrations exceeding 10(-4) M. Thus, the reaction of tubulin oligomerization is relatively resistant to factors preventing the microtubules assembly. This probably means that there are at least two types of intereaction between tubulin molecules: 1) bonds in microtubules which are sensitive to colchicine, Ca2+ and cold, and which are formed only in the presence of nucleosidetriphosphates; 2) bonds in 32S tubulin oligomer which are more stable and do not need in exogenous nucleotides.
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PMID:[32S Tubulin oligomer. The resistance to factors suppressing the microtubule formation]. 102 74

Melittin (MLT), a 26-residue cationic (net charge +5 at pH 7.2) peptide from bee venom, is well known to be a monomeric, approximately random coil; but when its charges are reduced by titration, by acetylation (net charge +2) or succinylation (net charge -2), or by screening by salt, it goes over to tetrameric alpha-helix. The conversion is promoted by raising the peptide concentration. The tetramer is held together by hydrophobic forces. We have changed the net charge to -6 by acylation with acetylcitric anhydride (a new acylating agent); this anionic derivative forms tetrameric helix at neutral pH, without salt, and at relatively low concentration, conditions under which the cationic MLT does not become helical. Thus, a high net charge is not sufficient to prevent association and helix formation. We have synthesized an anionic melittin analogue of MLT (E-MLT; net charge -4) in which all five lysine and arginine residues are replaced with glutamate, and acetyl and succinyl derivatives of E-MLT (net charges -5 and -6). All three of these are resistant to helix formation. They require much higher NaCl or NaClO4 concentration for helix formation than does MLT. Even CaCl2, MgCl2, and spermine.4HCl are less effective in helicizing E-MLT than MLT. MLT, at pH 7.2, shows increasing helix as the peptide concentration increases (8-120 microM), but E-MLT and its acyl derivatives do not. MLT and acylated MLTs in the helical tetramer show both cold- and heat-induced unfolding, with maximum stability near room temperature. At high temperature, a significant amount of residual structure remains. Heating (to 100 degrees C) monomeric MLT (i.e., MLT at low concentration) or E-MLT results in a monotonic increase in negative ellipticity. In 1.0 M NaCl, E-MLT (at sufficiently high concentration) also shows cold and hot unfolding. The results are discussed in respect to charge-charge and charge-dipole interactions, and hydrophobic effects. E-MLT is also discussed in relation to proteins of halophilic bacteria, which have higher proportions of anionic residues than do corresponding proteins of nonhalophiles.
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PMID:Conformational studies of anionic melittin analogues: effect of peptide concentration, pH, ionic strength, and temperature--models for protein folding and halophilic proteins. 142 Sep 81


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