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At least 343 records · Page 19Linked to original sources
PubMed1989

Mechanism of staphylococcal serine proteinase inactivation by lymphocytes and granulocytes.

Stricking differences were observed in the mechanism of interaction between staphylococcal serine proteinase and surface of human granulocytes or lymphocytes despite the fact that incubation of this enzyme with both types of cells leads to analogical decrease of proteinase activity. Interaction of proteinase with lymphocytes releases peptides smaller than these released spontaneously by non-treated lymphocytes or lymphocytes treated with DFP-proteinase. However, in supernatants of lymphocytes neither complex of proteinase with cell derived molecules nor changes of electrophoretic mobility of proteinase was found. Products of proteinase-lymphocyte reaction have a proliferative effect on intact lymphocytes, which is greater that the one of active proteinase. On the other hand granulocytes are resistant to proteinase and bind active proteinase as well as the DFP-proteinase in the receptor mediated way, followed by endocytosis with the affinity similar to the one in monocytes.

Electrophoresis, Polyacrylamide Gel↗
PubMed1979

Human serum and epithelial spread in tissue culture.

The dependence of epithelial spread on human serum in culture has been studied. Using measured pieces of mouse ear skin epithelial outgrowth about floating explants (epiboly) and from adherent explants was studied. Where compared directly the two systems show similar results. Because of its ease of quantitation, the adherent explant culture was studied in greater detail. In this system in the presence of serum appreciable spread was found only after 48 h but spread continued for at least the next 4 days. In the absence of serum only minimal epithelial spread occurred. Adding serum to deficient media enhanced spreading and removing serum from media depressed spreading. The extent of spread appeared independent of mouse age for the first 4-10 weeks though 2-week-old mouse skin showed quantitatively greater spreading. The activity in human serum responsible for epithelial spread acts under conditions of minimal DNA synthesis and is not reproduced by bovine serum albumin, fetuin, or serum that had been exposed to 100 degrees C for 5 min. The activity is not dialyzable and it is resistant to the protease inhibitors DFP and PMSF. These studies suggest that a specific serum component(s) serves to support epithelial spread in vitro.

Age Factors↗
PubMed1986

Serine proteinases in human cutaneous mastocytosis.

The main chymotryptic and tryptic proteinases of human skin were found in high-salt extracts of human dermis. The levels of these enzymes were markedly increased in salt extracts of human cutaneous mastocytosis as compared to the levels found in extracts of involved skin from the same patients, human cutaneous hemangiomas, and normal human skin. These data suggest that the chymotryptic and tryptic proteinases of human skin are primarily of mast-cell origin.

Biopsy↗
PubMed1977

Development and disappearance of subsensitivity to pilocarpine following a single administration of the irreversible anticholinesterase angent, DFP.

The present study examined the possibility that subsensitivity to pilocarpine might occur following a single injection of the irreversible anticholinesterase agent, DFP. In one experiment male Sprague-Dawley rats were trained to drink from experimental drinking chambers for 1/2 h per day. After establishment of baselines, pilocarpine hydrochloride (8 mg/kg) was injected i.p. 5 min before the drinking session. One week later DFP or the arachis oil vehicle (1 mg/kg) was injected intramuscularly and injections of pilocarpine were given at varying times thereafter. The suppression of water intake by this dose of pilocarpine was unaffected by pretreatment with arachis oil, but was markedly attenuated by pretreatment with DFP. This subsensitivity was first observed on the second day but had largely disappeared by the 14th day. DFP was found to have comparable effects on water intake and brain acetylcholinesterase activity when the injections were separated by 20 days. In a second experiment the hypothermic effects of pilocarpine were found to be reduced in rats acutely treated with DFP. These data establish that subsensitivity to pilocarpine occurs following a single administration of DFP. This subsensitivity could reflect a reduced sensitivity of postsynaptic receptors to acetylcholine, which may partially account for the behavioural recovery of the rats while acetylcholinesterase activity is still markedly depressed.

Acetylcholinesterase↗
PubMed1979

Development of behavioral tolerance: a search for subcellular mechanisms.

Development of behavioral tolerance is one of the processes by which living organisms adjust to changes in their internal and external environments. The search for neurochemical mechanisms underlying such processes requires the testing of many hypotheses. The present study was designed to examine the possible involvement of certain subcellular events. The concentrations of acetylcholine (ACh) and choline (Ch), the high-affinity transport of Ch, and the rate of synthesis of ACh were measured in synaptosomes prepared from the brains of rats. The assays were made at critical times during the acute changes in behavior induced by administration of the anticholinesterase, di-isopropylfluorophosphate, and during the development of behavioral tolerance to this compound as chronicity of administration continued. No statistically significant differences were found among treatment groups in the total concentration of ACh or Ch, the synthesis of ACh, or the high-affinity transport of Ch. These results, plus evidence from previous experiments, indicate that the development of behavioral tolerance does not relate to the factors studied. Consequently, alternative mechanisms should be considered. In addition to changes in cholinergic (muscarinic) receptors already shown to occur concomitantly with the development of behavioral tolerance, it is suggested that the possible involvement of mechanisms controlling release of ACh should be studied.

Acetylcholine↗
PubMed1982

Selective breeding for diisopropyl fluorophosphate-sensitivity: behavioural effects of cholinergic agonists and antagonists.

The behavioral effects of cholinergic agonists and antagonists were examined in two lines of rats which have been developed through selective breeding techniques to be differentially sensitive to the anticholinesterase diisopropyl fluorophosphate (DFP). The line of rats which were determined to be more sensitive to DFP (Flinders S line) were also more sensitive to the depressant effects of the agonists pilocarpine and physostigmine on locomotor activity, water intake, and operant responding maintained by water reward. In contrast, the locomotor stimulant effects of scopolamine, a muscarinic antagonist, were less marked in the S-line rats, while the depressant effects of atropine and scopolamine on water intake and operant responding maintained by water reward were comparable in the two lines. The S-line rats were also significantly more sensitive to the hypothermic effects of pilocarpine and oxotremorine. These findings are consistent with the hypothesis that the S-line rats are more sensitive to the acute effects of DFP because they have a higher number of muscarinic-cholinergic receptors.

Animals↗
PubMed1981

The influence of ovariectomy on the sex-dependent effects of the anticholinesterase diisopropyl fluorophosphate.

Temperature and water uptake were reduced to a greater degree in ovariectomized female and normal male rats than in sham-operated female rats following an acute administration of 1 mg/kg of the anticholinesterase diisopropyl fluorophosphate (DFP). Ovariectomy also led to a significant reduction in the level of serum cholinesterase activity. These findings add further support for the hypothesis that the sex-dependent effects of DFP are due, at least in part, to sex differences in serum cholinesterase activity.

Animals↗
PubMed1977

Expression of esterases during ontogenesis of the flour beetle Tribolium castaneum (Tenebrionidae; Coleoptera).

Two electrophoretically fast-migrating, nonspecific esterases were detected in two strains of the flour beetle Tribolium castaneum and designated F (fast) and S (slow) according to their relative migration distances. Both isozymes are associated with the alimentary canal and display ontogenetic changes. Their activity is very low in the egg stage, increases in the larva, and declines dramatically in the pharate pupa and pupa. The overall activity in the pupal stage is low, yet increases gradually throughout this period. In the adult, the activity of the esterases rises sharply. The larval and adult F and S isozymes were found to hydrolyze alpha- and beta-naphthylacetate and alpha-naphthylpropionate with almost equal capacity. alpha-Naphthyl laurate was cleaved by the F enzyme of both larvae and adults. The F and S were insensitive to inhibitors of arylesterases and cholinesterases and were markedly inhibited by the organophosphate di-isopropylphosphorofluoridate (DFP) and could be classified as carboxylesterases. Differential sensitivities of larval and adult esterases to urea and heat treatment as well as to DFP may indicate the expression of different genes during metamorphosis.

Animals↗