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N S Orenstein

Publications and source records attributed to N S Orenstein.

10 recordsLinked to original sources
PubMed1978

Nerve growth factor: a protease that can activate plasminogen.

The single, highly stable form of mouse submandibular gland nerve growth factor (NGF), prepared as described by Young et al. [(1978) Biochemistry 17, 1490--1498] is a protease of restricted specificity that can convert plasminogen to plasmin. In the absence of plasminogen, NGF is not fibrinolytic, nor does it hydrolyze casein at a measurable rate. Treatment of NGF with diisopropyl fluorophosphate inhibits its ability to activate plasminogen as well as its capacity to hydrolyze certain synthetic arginine esters. These results indicate that NGF is a member of the class of serine proteases. Since NGF is known to be secreted at high concentrations in mouse saliva, it may serve to activate plasminogen (with subsequent fibrinolysis) somewhere in the alimentary tract. Plasminogen activation is the only known action of NGF upon a biologically important non-neural substrate.

Animals↗
PubMed1978

Plasminogen activator of guinea pig basophilic leukocytes: probable localization to the plasma membrane.

The plasminogen activator (PA) activity of guinea pig basophil-enriched leukocyte preparations was localized to basophils, and not to contaminating lymphocytes and eosinophils, by correlating PA activity with basophil frequency and, more directly, by means of an improved cytochemical method here described. PA activity was fully expressed in living cells in the absence of immunologic stimuli and was suppressed/lost to a variable extent by different techniques of cell disruption. Conversely, killed, but not living, basophils expressed significant plasminogen-independent fibrinolytic activity, presumably reflecting access of cytoplasmic proteases of broken basophils to fibrin substrate. The PA activity of intact cells was destroyed by gentle trypsinization under conditions that did not impair cell viability. When disrupted cells were ultracentrifuged on a sucrose density gradient, PA activity was absent from purified granules and was confined to fractions containing cell membranes. The simplest explanation of these data is that guinea pig basophils have PA activity associated with their plasma membranes. This conclusion has several important implications for basophil functions in cell-mediated and other immunologic reactions in vivo.

Animals↗
PubMed1978

Sulfated glycosaminoglycans of guinea pig basophilic leukocytes.

Cytoplasmic granules of basophilic leukocytes stain metachromatically and have been thought to contain sulfated glycosaminoglycans, presumably heparin. To test this hypothesis, we identified the [35S]glycosaminoglycans synthesized by guinea pig blood basophils in culture and in vivo. Basophils isolated from guinea pig blood were cultured for 20 hr in F12 medium--10% guinea pig serum containing sodium [35S]sulfate. Alternatively, basophils were purified from animals receiving repeated i.v. injections of sodium [35S]sulfate. Glycoaminoglycans were isolated from these basophils after pronase digestion and identified by the use of selective glycosaminoglycan-degrading enzymes. Approximately 55% of the [35S]glycosaminoglycans was degraded by chondroitinase AC, indicating the presence of chondroitin sulfate; an additional 30 to 35% could be degraded by chondroitinase ABC, indicating that dermatan sulfate was also present. The 15% glycosaminoglycan remaining after chondroitinase ABC digestion was degraded by purified heparitinase (heparanase), which has no effect on authentic heparin but degrades heparan sulfate. Thus, the glycosaminoglycan content of guinea pig basophils is a mixture of chondroitin sulfate, dermatan sulfate, and smaller amounts of heparan sulfate. No heparin was detected.

Animals↗
PubMed1977

Isolation of the cytoplasmic granules of guinea pig basophilic leukocytes: identification of esterase and protease activities.

Procedures were developed for isolating highly purified cytoplasmic granules of basophilic leukocytes from guinea pig peripheral blood. The methods involved disruption of cells in 0.34 M sucrose followed by a series of membrane filtrations and fractionation on sucrose density gradients. These preparations, up to 95% pure basophil granules by electron microscopy, contained a mixture of neutral esterases-proteases including caseinolytic activity; both trypsin- and chymotrypsin-like serine hydrolases were identified by means of appropriate inhibitors. Localization of at least one such activity to the basophil granule was confirmed by a cytochemical method; this activity was absent in contaminating lymphocytes and eosinophils. By contrast, several lysosomal enzymes, lactic dehydrogenase, and plasminogen activator activity, present in cell homogenates, were absent from purified granules. The granule matrix of guinea pig basophils, unlike the cytoplasmic granules of other granulocytes or mast cells, was little altered by high or low salt concentration but was disrupted into insoluble fragments by 0.01 N HCl and by Triton X-100. Granules were solubilized by papain and by urea-SDS but enzyme activity was destroyed. Triton X-100 incubation with freeze-thawing proved to be the optimal method for extracting esterase activities. Esterase activities were not released from basophils under conditions of anaphylactic degranulation that liberated the great majority of basophil granule histamine.

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