Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0085593 (chills)
 4,268 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cleavage of prorenin's prosegment causes irreversible formation of renin. In contrast, renin activity is reversibly exposed when prorenin is acidified to pH 3.3. Nonetheless, acidification of plasma results in irreversible activation of prorenin, because endogenous proteases cleave the prosegment of acid-activated prorenin. Chilling of plasma results in irreversible cryoactivation of prorenin. In this study we investigated whether cryoactivation of purified prorenin is reversible. The intrinsic renin activity of recombinant human prorenin was measured by an enzyme kinetic assay using partially purified human angiotensinogen as substrate. Results are expressed as a percent (mean +/- S.E.) of the maximal activity exposed after limited proteolysis by trypsin. The intrinsic renin activity of two pools (0.3 and 0.06 Goldblatt units/ml) was 1.5% +/- 0.3 and 1.2% +/- 0.6 at 37 degrees C. Activity increased to 19% +/- 0.3 and 26% +/- 0.5 after incubation at 0 degrees C and to 5.4% +/- 0.5 and 2.1% +/- 1.2 at room temperature. Cryoactivation did not occur in buffers containing more than 1 M NaCl. It took 8 min at 37 degrees C or 180 min at room temperature for cryoactivated prorenin to lose half of its intrinsic renin activity. It took 48 and 26 h, respectively, at 0 degree C for the two pools of prorenin at 37 degrees C to regain half of their maximum intrinsic activity at 0 degrees C. A direct immunoradiometric assay that detects active renin but not prorenin was able to detect cryoactivated prorenin. These results show that human prorenin can be reversibly cryoactivated in buffers of low ionic strength and has greater intrinsic activity at room temperature than at 37 degrees C.
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PMID:Reversible cryoactivation of recombinant human prorenin. 160 50

Eggshells of Nematodirus battus leaked trehalose 4 hr after being stimulated to hatch, and became permeable to trypan blue at their poles; 80% of eggs were stained blue 24 hr later. Exogenous application of ruthenium red significantly inhibited chill- and sodium fluoride-stimulated hatching, 50% hatch inhibition occurring in 44.67 +/- 2.2 and 8.5 +/- 1.5 microM, respectively. Lanthanum chloride, however, was not as inhibitory as ruthenium red on fluoride-stimulated hatching, 50% occurring at 31.60 +/- 1.25 microM. A Scatchard plot of the competitive binding of ruthenium red to eggshells demonstrated a high-affinity binding site for calcium, KCa' = 1.92 microM and a second, low-affinity site, KCa" = 1169.60 microM. Ruthenium red binding was significantly reduced by several enzymes, e.g., EGTA-buffered trypsin reduced binding by 73%. Radioiodinated concanavalin A also bound competitively to the eggshells in the presence of alpha-D-glucosyl-alpha-D-glucopyranoside and alpha-methyl-D-mannopyranoside. Eggshells incorporated phosphorus-32 from ATP after chilling or on exposure to sodium fluoride; gel filtration of solubilized homogenates of these samples showed that two proteins were radiolabelled with molecular weights of 38 X 10(3) and 8 X 10(3) Da, respectively. This phosphorylation was inhibited by N-ethylmaleimide, which also prevented hatching.
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PMID:Nematodirus battus: permeability changes, calcium binding, and phosphorylation of the eggshell during hatching. 620 83

Neonatal and adult keratinocytes isolated from thin sections of split-thickness skin by trypsin-release show a preferential and strong attachment to collagen when compared to plastic, fibronectin-coated plastic, glass, or agar gels. We have investigated the reactive groups of keratinocytes and collagen required for this interaction and have determined the kinetics of attachment. At 37 degrees C both neonatal and adult keratinocytes show a rapid and irreversible attachment to collagen, reaching a plateau phase at 30-60 minutes. The cells cannot be replaced from the gel by extensive washing or by conditions normally expected to break ionic bonds. Chilling to 0 degree C before plating completely inhibits attachment, and heating at 37 degrees C reverses the inhibition. One cycle of freezing and thawing of cells inhibits the interaction. Removal of sialic residues from keratinocytes before plating with neuraminidase, or oxidation of sugars with periodate, does not inhibit attachment or growth, indicating that cell carbohydrates are not required for interaction with collagen. Neither denaturation of collagen with 8 M urea nor oxidation of sugar side chains on the gel with periodic acid affects attachment or growth. However, reaction of free-SH groups with iodoacetic acid or -NH2 groups with dinitrofluorobenzene of the gel completely inhibits growth. Blocking the guanidyl residues of collagen arginine with cyclohexanedione markedly alters all aspects of attachment, growth, and morphology, producing new and completely unique growth patterns. These studies indicate that specific chemical groups on collagen affect keratinocyte-matrix interactions and that the availability of specific residues in collagen directly influences growth and maturation. Most vertebrate cells remain closely associated with extracellular collagenous substances throughout their lifespan. The collagen may be present in both collagen fibers and in reticular fibers as well as in basement membranes. The way cells interact with and are anchored to these various substrata influences a number of important cellular functions including growth and maturation and the synthesis of extracellular matrix components. Skin epithelial cells display a particularly striking and strong dependence on collagen for growth. When plated on a collagen gel, the plating efficiency and growth is increased several-fold compared to other substrates such as glass, plastic, or agar. More recently, the initial observations on the selective attachment of keratinocytes to collagen gels have been extended by Murray et al., who demonstrated that guinea pig keratinocytes show increased plating efficiencies on Type IV collagen gels. In these studies, we have examined the mechanisms for keratinocyte-collagen interaction, and described the kinetics of attachment, the reactive sites on the cell and collagen, and the effects of chemical modification of collagen on the expression of the keratinocytes phenotype.
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PMID:Effect of chemical modification of keratinocytes and collagen in keratinocyte-collagen interactions. 723 89