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Biomedical subjects

N S Orenstein

Publications and source records attributed to N S Orenstein.

16 recordsLinked to original sources
PubMed1983

Cryptic and active plasminogen activators secreted by line 10 tumor cells in culture.

Line 10 guinea pig carcinoma cells cultured in serum-free medium for 4 hr elaborate plasminogen activator (PA) activity that remained in the supernatant after ultracentrifugation (100,000 X g, 90 min). PA activity in line 10 conditioned medium occurred in both active and cryptic forms. The vast majority of active PA adsorbed to lysine-Sepharose and could be eluted at low pH as several activities that electrophoresed in the Mr 50,000 to 80,000 range on nonreduced sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A small amount of active PA, running in the Mr 50,000 to 60,000 region, and cryptic PA did not adhere to lysine-Sepharose. Treatment of lysine-Sepharose-nonadherent fractions with catalytic amounts of plasmin or trypsin induced substantial new PA activity that adsorbed to lysine-Sepharose, bound [3H]diisopropylfluorophosphate, and that electrophoresed as several bands of activity with molecular weights from 50,000 to greater than 100,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Of additional interest, the amount of active PA measured in conditioned medium was substantially increased when certain protease inhibitors, tranexamic acid, epsilon-aminocaproic acid, or Trasylol, were included during culture.

Animals↗
PubMed1981

Tumor shedding and coagulation.

Three syngeneic carcinomas from two species shed plasma membrane vesicles when cultured in vitro or grown in the ascites tumor form in vivo. Shed vesicles carry procoagulant activity that can account for the activation of the clotting system and the fibrin deposition associated with these and many other types of malignancy in animals and man.

Animals↗
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.

Animals↗
PubMed1974

Purification on renografin density gradients of Chlamydia trachomatis grown in the yolk sac of eggs.

Chlamydia trachomatis grown in the yolk sac of embryonated eggs was purified by centrifugation on continuous isopycnic Renografin density gradients. A band of chlamydial particles with a buoyant density of 1.20 contained 70% of the starting particles, and electron microscopy revealed the virtual absence of contaminating egg material. Centrifugation on Renografin gradients caused only a moderate decrease in infectivity. For large-scale purification, infected yolk sac was centrifuged through Renografin solutions, resulting in greater than 60% recovery of starting chlamydial particles, but less than 1% recovery of the dry weight and protein.

Animals↗
PubMed1973

Immunity to chlamydial infections of the eye. V. Passive transfer of antitrachoma antibodies to owl monkeys.

Previous studies have shown that owl monkeys which have had a trachoma agent infection were subsequently highly resistant to challenge by both homologous and heterologous organisms. In the present study, passive transfer of owl monkey serum containing antitrachoma antibody from immune monkeys did not protect recipient monkeys from infectious challenge with homologous trachoma. Antibody was not detectable in eye secretions of the recipient monkeys until the intensity of infection was waning, suggesting but not proving that local antibody synthesis rather than simple transudation of serum antibody occurs.

Animals↗