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[Severe hereditary protein C deficiency in a newborn infant with fulminant purpura--successful treatment with phenprocoumon].

A newborn baby was born with scrotal hematoma and a diagnosis of testicular torsion was made. This diagnosis proved false, when the hematoma was resorbed after a few days and other hematomas developed instead (abdomen, elbow, foot, scalp). A total of nine hemorrhagic episodes were observed, most of them occurring on the scalp. All lesions were sharply delineated, started with red to purple discoloration and then turned to bluish-black indicating gangrene. Histology revealed extensive bleeding into the corium, fibrin thrombi within the capillaries, and complement and IgG in the small arterial walls. Each bleeding was associated with hypofibrinogenemia and thrombocytopenia. A diagnosis of hereditary protein C deficiency was made. Blood levels were consistent with heterozygosity of both the parents and homozygosity of the child. Bleedings were controlled by Cohn fraction I and heparin. It was impossible, however, to prevent further hemorrhage by continuous i.v. heparin. In addition aprotinin, epsilon-aminocaproic acid, AT III, and prednisone were ineffective. Continuous remission finally could be sustained with oral phenprocoumon.

4-Hydroxycoumarins↗

Plasminogen activator secretion by granule neurons in cultures of developing cerebellum.

Dispersed cell cultures were established from 7- to 9-day postnatal mouse cerebellum. The fibrin slice method was used to obtain a localization of plasminogen activator production to specific cells. Fibrinolytically active cells were small (5- to 8-micrometer diameter), round, and occurred singly or in aggregates. Fibrinolysis was both plasminogen and time dependent, inhibitable by epsilon-aminocaproic acid and soybean trypsin inhibitor and did not occur when cells were fixed in formalin prior to the fibrin overlay. Strong fibrin degradation occurred only when granule neurons were abundant in the cultures. These plasminogen activator secreting cells were identified as granule neurons by cell separation methods, nuclear morphology, and their ability to bind tetanus toxin and rabbit antiserum against mouse cerebellum (anti-Cbl-1 antiserum). Plasminogen activator also could be quantified in fractionated tissue homogenates or in cell culture medium by the 125I-labeled fibrin plate assay. Fibrinolysis in cerebellar extracts was 95% dependent on the presence of added plasminogen; furthermore, the activity was greater in cerebellar extracts as compared to cerebral cortex of the same age. At the age examined, the cerebellum contains many migratory neurons, and plasminogen activator production may be involved in the process of cell movement.

Animals↗

A rapid and sensitive method for detection and quantification of calcineurin and calmodulin-binding proteins using biotinylated calmodulin.

Purified bovine brain calmodulin was biotinylated with biotinyl-epsilon-aminocaproic acid N-hydroxysuccinimide. Biotinylated calmodulin was used to detect and quantify calmodulin-binding proteins following both protein blotting and slot-blot procedures by using alkaline phosphatase or peroxidase coupled to avidin. When purified bovine brain calcineurin, a calmodulin-dependent protein phosphatase, was immobilized on nitrocellulose slot blots, biotinylated calmodulin bound in a calcium-dependent saturable manner; these blots were then quantified by densitometry. Biotinylated calmodulin was able to detect as little as 10 ng of calcineurin, and the binding was competitively inhibited by addition of either native calmodulin or trifluoperazine. When biotinylated calmodulin was used to probe protein blots of crude brain cytosol and membrane preparations after gel electrophoresis, only protein bands characteristic of known calmodulin-binding proteins (i.e., calmodulin-dependent protein kinase, calcineurin, spectrin) were detected with avidin-peroxidase or avidin-alkaline phosphatase procedures. Purified calcineurin was subjected to one- and two-dimensional gel electrophoresis and protein blotting; as expected, only the 61-kDa calmodulin-binding subunit was detected. When the two-dimensional protein blot was incubated with biotinylated calmodulin and detected with avidin-alkaline phosphatase, several apparent forms of the 61-kDa catalytic subunit were detected, consistent with isozymic species of the enzyme. The results of these studies suggest that biotinylated calmodulin can be used as a simple, sensitive, and quantifiable probe for the study of calmodulin-binding proteins.

Animals↗

Modulation of granule cell migration by a glia-derived protein.

Cultured explants from early postnatal mouse cerebellum were used to examine the influence of a 43-kDa glia-derived neurite-promoting factor (GdNPF) on the migration of [3H]thymidine-labeled granule cell neurons. GdNPF, which is a potent serine protease inhibitor, significantly reduced the extent of granule cell migration in a dose-dependent manner. This effect could be neutralized by addition of thrombin, which binds GdNPF. Other protease inhibitors such as aprotinin, hirudin, soybean trypsin inhibitor, leupeptin, 6-aminocaproic acid, and D-Phe-Pro-ArgCH2Cl do not show this inhibitory effect. These results demonstrate that a glia-derived protein can regulate the migration of postmitotic neurons, an important cellular event in the development of the nervous system.

Animals↗

Plasmin catalyzes binding of lipoprotein (a) to immobilized fibrinogen and fibrin.

Lipoprotein (a) [Lp(a)] is a plasma component whose concentration is related to the development of atherosclerosis, although the underlying mechanisms are not known. Lp(a) contains a unique structure, apolipoprotein (a), that shares partial homology with plasminogen. We now report that plasmin catalyzes the binding of Lp(a) to both immobilized fibrinogen and fibrin in a manner analogous to our previously reported studies with plasminogen. Plasmin treatment of immobilized fibrinogen induces a 3.7-fold increase in Lp(a) binding. Low density lipoprotein, molecules similar to Lp(a) but lacking apolipoprotein (a), bind poorly to immobilized fibrinogen and binding is not increased by plasmin. Trypsin but not neutrophil elastase also increases the binding of Lp(a) to fibrinogen. Lp(a) also complexes to plasmin-fibrinogen digests, and binding increases in proportion to the time of plasmin-induced fibrinogen degradation. Lp(a) binding is lysine-binding site dependent as it is inhibited by epsilon-aminocaproic acid. Lp(a) inhibits the binding of plasminogen to plasmin-modified immobilized fibrinogen, indicating that both molecules compete for similar lysine-binding sites. These findings demonstrate an affinity between Lp(a) and protease-modified fibrinogen or fibrin and thereby provide a potential mechanism to explain the association between thrombosis, coronary atherosclerosis, and increased blood concentrations of Lp(a).

Arteriosclerosis↗

Homocysteine and other sulfhydryl compounds enhance the binding of lipoprotein(a) to fibrin: a potential biochemical link between thrombosis, atherogenesis, and sulfhydryl compound metabolism.

We have previously shown that lipoprotein(a) [Lp(a)], an atherogenic lipoprotein that contains apolipoprotein(a), which shares partial structural homology to plasminogen, binds to a plasmin-modified fibrin surface, and we have postulated that this interaction may be atherogenic. Moderate elevations in blood homocysteine, a relatively common condition, predispose to premature atherosclerosis. The reasons for this are not established. We now report that homocysteine, at concentrations as low as 8 microM, significantly increases the affinity of Lp(a) for fibrin. Homocysteine induces a 20-fold increase in the affinity between Lp(a) and plasmin-treated fibrin and a 4-fold increase with unmodified fibrin. Lp(a) binding is inhibited by epsilon-aminocaproic acid, indicating lysine binding site specificity. Homocysteine does not enhance the binding of Lp(a) to other surface-bound proteins. Cysteine, glutathione, and N-acetylcysteine also increase the affinity between Lp(a) and fibrin. Homocysteine does not affect the binding of low density lipoprotein or plasminogen to fibrin, nor does it alter the gel-filtration elution pattern of Lp(a). Immunoblot analysis documents the fact that homocysteine partially reduces Lp(a). These results suggest that homocysteine alters the intact Lp(a) particle so as to increase the reactivity of the plasminogen-like apolipoprotein(a) portion of the molecule. The observation that sulfhydryl amino acids increase Lp(a) binding to fibrin suggests a biochemical relationship between sulfhydryl compound metabolism, thrombosis, and atherogenesis.

Blotting, Western↗

Urokinase and tissue-type plasminogen activator are required for the mitogenic and chemotactic effects of bovine fibroblast growth factor and platelet-derived growth factor-BB for vascular smooth muscle cells.

The present study was undertaken to evaluate in vitro the relative importance of tissue-type plasminogen activator (t-PA) and urokinase-type plasminogen activator (u-PA) in the mitogenic and chemotactic potential of bovine fibroblast growth factor (bFGF) and platelet-derived growth factor (PDGF)-BB for smooth muscle cells (SMC). Aortic SMC were isolated from transgenic mice showing single inactivations of the t-PA, u-PA, plasminogen activator inhibitor-1, or urokinase-type plasminogen activator receptor (u-PAR) genes. With regard to serum-induced proliferation, all cell types showed similar responses. However, SMC isolated from t-PA-deficient mice did not proliferate or migrate in response to PDGF, whereas SMC isolated from u-PA-deficient animals appeared to be much less sensitive to bFGF than the cells isolated from the other animals. Supplementation of cells from deficient animals with exogenous murine t-PA or u-PA restored the normal response of the growth factors with regard to both migration and proliferation. The mitogenic and chemotactic responses of bFGF were specifically inhibited in u-PAR-deficient cells or in wild-type SMC, cultured in the presence of antibodies to u-PAR. The role of u-PA and t-PA in bFGF and PDGF-induced growth and migration of SMC was not dependent on plasmin generation and activity as demonstrated by the inactivity of epsilon-aminocaproic acid and aprotinin. A 4-5-fold increase in the steady-state levels of u-PA and t-PA mRNA and proteins were observed after 24 h of incubation of the cell cultures with bFGF and PDGF-BB, respectively. These results therefore indicate that, at least in vitro, t-PA is an important element of the activity of PDGF-BB with regard to the proliferation and migration of SMC whereas u-PA is a key factor in the effect of bFGF on SMC.

Animals↗

Expression of a recombinant apolipoprotein(a) in HepG2 cells. Evidence for intracellular assembly of lipoprotein(a).

Apolipoprotein(a) (apo(a)), a large glycoprotein with extensive homology to plasminogen, forms a complex with apolipoprotein B100 (apoB100), which circulates in human plasma in the form of lipoprotein(a) (Lp(a)). Evidence indicates that the association of apo(a) with apoB100 occurs in the extracellular environment. We have reevaluated the possibility that apo(a)-B100 association can also occur as an intracellular event through studies with HepG2 cells stably transfected with an apo(a) minigene. Several lines of evidence support this possibility. First, continued Lp(a) production was demonstrated following incubation of transfected HepG2 cells with anti-apo(a) antisera, conditions that effectively block the fluid-phase association of apo(a) and apoB100 in vitro. Second, an apo(a)-B100 complex was detectable in Western blot analyses of transfected HepG2 lysates following immunoprecipitation with anti-apo(a) antisera. These studies incorporated precautions to eliminate cell-surface attachment of preformed apo(a)-B100 complexes to the low density lipoprotein receptor and were conducted in the presence of the lysine analog epsilon-aminocaproic acid, which precludes apo(a)-B100 association occurring during the isolation and analyses. Third, the presence of an intracellular apo(a)-B100 complex was demonstrated in lipoproteins isolated from microsomal contents. Of particular significance was the observation that this complex contained the precursor form of apo(a), which is not secreted, in addition to the mature, recombinant form. Finally, direct evidence was provided for the synthesis of a precursor form of apo(a) in a nascent intracellular complex with apoB100 following treatment of transfected HepG2 cells with brefeldin A plus N-acetyl-leucyl-leucyl-norleucinal. Taken together, these data suggest that apo(a)-B100 association can occur as an intracellular event in a human hepatoma-derived cell line, raising important implications for the regulation of Lp(a) secretion from human liver.

Apolipoprotein B-100↗

Acceleration of plasminogen activation by tissue plasminogen activator on surface-bound histidine-proline-rich glycoprotein.

Histidine-proline-rich glycoprotein (HPRG), also known as histidine-rich glycoprotein, is a major plasminogen-binding protein. In this work we characterized extensively the circumstances under which HPRG accelerates plasminogen activation and the specificity of this effect. Soluble HPRG did not significantly influence plasminogen activation. In contrast, native HPRG bound to hydrazide or nickel chelate surfaces strongly stimulated the activation of plasminogen by tissue plasminogen activator, but not by urokinase or streptokinase. The efficiency of activation on surface-bound HPRG was increased for Glu-plasminogen (41-fold), Lys-plasminogen (17-fold), and cross-linked Glu-plasminogen (11-fold) but not for mini-plasminogen, and was mainly due to a decrease in the apparent Km. A reduced susceptibility to inhibition by chloride ions contributed to the higher activation rate of Glu-plasminogen on an HPRG surface. The immobilized N- and C-terminal domains, but not the histidine-proline-rich domain of HPRG, also bound plasminogen and stimulated its activation. HPRG-enhanced plasminogen activation was proportional to the quantity of HPRG immobilized and was abolished by anti-HPRG antiserum, by low concentrations of epsilon-aminocaproic acid, by methylation of lysine residues in HPRG, and by treatment of HPRG with carboxypeptidase B. Soluble HPRG and a plasminogen fragment, kringle 1-2-3, acted as competitive inhibitors by binding to plasminogen and immobilized HPRG, respectively. The interaction of the conserved C-terminal lysine of HPRG with the high affinity lysine binding site of plasminogen is necessary and sufficient to accelerate plasminogen activation. Unlike other stimulators of plasminogen activation, the effect of HPRG on fibrinolysis is modulated by factors that influence the equilibrium between solution and surface-bound HPRG.

Animals↗

The role of annexin II tetramer in the activation of plasminogen.

Annexin II tetramer (AIIt) is a major Ca2+-binding protein of endothelial cells which has been shown to exist on both the intracellular and extracellular surfaces of the plasma membrane. In this report, we demonstrate that AIIt stimulates the activation of plasminogen by facilitating the tissue plasminogen activator (t-PA)-dependent conversion of plasminogen to plasmin. Fluid-phase AIIt stimulated the rate of activation of [Glu]plasminogen about 341-fold compared with an approximate 6-fold stimulation by annexin II. AIIt bound to [Glu]plasminogen(S741C-fluorescein) with a Kd of 1. 26 +/- 0.04 microM (mean +/- S.D., n = 3) and this interaction resulted in a large conformational change in [Glu]plasminogen. Kinetic analysis established that AIIt produces a large increase of about 190-fold in the kcat, app and a small increase in the Km,app which resulted in a 90-fold increase in the catalytic efficiency (kcat/Km) of t-PA for [Glu]plasminogen. AIIt also stimulated the t-PA-dependent activation of [Lys]plasminogen about 28-fold. Furthermore, other annexins such as annexin I, V, or VI did not produce comparable activation of t-PA-dependent conversion of [Glu]plasminogen to plasmin. The stimulation of the activation of [Glu]plasminogen by AIIt was Ca2+-independent and inhibited by epsilon-aminocaproic acid. AIIt bound to human 293 cells potentiated t-PA-dependent plasminogen activation. AIIt that was bound to phospholipid vesicles or heparin also stimulated the activation of [Glu]plasminogen 5- or 11-fold, respectively. Furthermore, immunofluorescence labeling of nonpermeabilized HUVEC revealed a punctated distribution of AIIt subunits on the cell surface. These results therefore identify AIIt as a potent in vitro activator of plasminogen.

Annexin A2↗

Specific interaction of angiostatin with integrin alpha(v)beta(3) in endothelial cells.

Angiostatin, the N-terminal four kringles (K1-4) of plasminogen, blocks tumor-mediated angiogenesis and has great therapeutic potential. However, angiostatin's mechanism of anti-angiogenic action is unclear. We found that bovine arterial endothelial (BAE) cells adhere to angiostatin in an integrin-dependent manner and that integrins alpha(v)beta(3), alpha(9)beta(1), and to a lesser extent alpha(4)beta(1), specifically bind to angiostatin. alpha(v)beta(3) is a predominant receptor for angiostatin on BAE cells, since a function-blocking antibody to alpha(v)beta(3) effectively blocks adhesion of BAE cells to angiostatin, but an antibody to alpha(9)beta(1) does not. epsilon-Aminocaproic acid, a Lys analogue, effectively blocks angiostatin binding to BAE cells, indicating that an unoccupied Lys-binding site of the kringles may be required for integrin binding. It is known that other plasminogen fragments containing three or five kringles (K1-3 or K1-5) have an anti-angiogenic effect, but plasminogen itself does not. We found that K1-3 and K1-5 bind to alpha(v)beta(3), but plasminogen does not. These results suggest that the anti-angiogenic action of angiostatin may be mediated via interaction with alpha(v)beta(3). Angiostatin binding to alpha(v)beta(3) does not strongly induce stress-fiber formation, suggesting that angiostatin may prevent angiogenesis by perturbing the alpha(v)beta(3)-mediated signal transduction that may be necessary for angiogenesis.

Angiogenesis Inhibitors↗

Ligand exchange between proteins. Exchange of biotin and biotin derivatives between avidin and streptavidin.

We have studied the structural elements that affect ligand exchange between the two high affinity biotin-binding proteins, egg white avidin and its bacterial analogue, streptavidin. For this purpose, we have developed a simple assay based on the antipodal behavior of the two proteins toward hydrolysis of biotinyl p-nitrophenyl ester (BNP). The assay provided the experimental basis for these studies. It was found that biotin migrates unidirectionally from streptavidin to avidin. Conversely, the biotin derivative, BNP, is transferred in the opposite direction, from avidin to streptavidin. A previous crystallographic study (Huberman, T., Eisenberg-Domovich, Y., Gitlin, G., Kulik, T., Bayer, E. A., Wilchek, M., and Livnah, O. (2001) J. Biol. Chem. 276, 32031-32039) provided insight into a plausible explanation for these results. These data revealed that the non-hydrolyzable BNP analogue, biotinyl p-nitroanilide, was almost completely sheltered in streptavidin as opposed to avidin in which the disordered conformation of a critical loop resulted in the loss of several hydrogen bonds and concomitant exposure of the analogue to the solvent. In order to determine the minimal modification of the biotin molecule required to cause the disordered loop conformation, the structures of avidin and streptavidin were determined with norbiotin, homobiotin, and a common long-chain biotin derivative, biotinyl epsilon-aminocaproic acid. Six new crystal structures of the avidin and streptavidin complexes with the latter biotin analogues and derivatives were thus elucidated. It was found that extending the biotin side chain by a single CH(2) group (i.e. homobiotin) is sufficient to result in this remarkable conformational change in the loop of avidin. These results bear significant biotechnological importance, suggesting that complexes containing biotinylated probes with streptavidin would be more stable than those with avidin. These findings should be heeded when developing new drugs based on lead compounds because it is difficult to predict the structural and conformational consequences on the resultant protein-ligand interactions.

Avidin↗

Identification and characterization of novel lysine-independent apolipoprotein(a)-binding sites in fibrin(ogen) alphaC-domains.

Accumulation of lipoprotein(a) (Lp(a)) in atherosclerotic plaques is mediated through interaction of fibrin-(ogen) deposits with the apolipoprotein(a) (apo(a)) moiety of Lp(a). It was suggested that because apo(a) competes with plasminogen for binding to fibrin, causing inhibition of fibrinolysis, it could also promote atherothrombosis. Because the fibrin(ogen) alphaC-domains bind plasminogen and tissue-type plasminogen activator with high affinity in a Lys-dependent manner, we hypothesized that they could also bind apo(a). To test this hypothesis, we studied the interaction between the recombinant apo(a) A10 isoform and the recombinant alphaC-fragment (Aalpha-(221-610)) corresponding to the alphaC-domain by enzyme-linked immunosorbent assay and surface plasmon resonance. Both methods revealed a high affinity interaction (Kd = 19-21 nm) between the immobilized alphaC-fragment and apo(a), indicating that the former contains an apo(a)-binding site. This affinity was comparable to that of apo(a) for fibrin. At the same time, no interaction was observed between soluble fibrinogen and immobilized apo(a), suggesting that, in the former, this and other apo(a)-binding sites are cryptic. Further experiments with truncated recombinant variants of the alphaC-fragment allowed localization of the apo(a)-binding site to the Aalpha-(392-610) region. The presence of epsilon-aminocaproic acid only slightly inhibited binding of apo(a) to the alphaC-fragment, indicating the Lys-independent nature of their interaction. In agreement, the influence of plasminogen or tissue-type plasminogen activator on binding of apo(a) to the alphaC-fragment was minimal. These results indicate that the alphaC-domains contain novel high affinity apo(a)-binding sites that may provide a Lys-independent mechanism for bringing Lp(a) to places of fibrin deposition such as injured vessels or atherosclerotic lesions.

Apolipoproteins↗

Horse plasma ceruloplasmin molecular weight and subunit analysis.

Ceruloplasmin is a blue copper-containing serum glycoprotein with oxidase activity. It as been proposed that the physiological function of ceruloplasmin involves the oxidation of ferrous iron and its incorporation into apotransferrin. There are several reports demonstrating that ceruloplasmin is made up of multiple chains. Ryden has questioned the multichain structure of ceruloplasmin from human, pig, horse and rabbit sera, arguing that the dissociation observed by previous workers could be attributed to cleavage of labile bands in the protein by enzymatic contaminants present in commercial preparations of the protein. By introducing epsilon-aminocaproic acid, a general protease inhibitor, at the beginning of the enzyme preparation, Ryden proposed a single-chain structure for ceruloplasmin. On the contrary the results presented by Freeman and Daniel showed that human ceruloplasmin is a multichain protein. In this paper we report a new purification method for horse ceruloplasmin which furnishes a homogeneous protein preparation in high yield and with good reproducibility. This procedure allowed to determine with greater accuracy the molecular mass of the protein, of 120,000 daltons by gel chromatography and 115,000 daltons by SDS gel electrophoresis. The protein is composed of one unit only and contains 6 copper atoms. Horse ceruloplasmin is a glycoprotein containing about 20% carbohydrate by weight.

Animals↗

Treatment of patients with intracranial arterial aneurysms in the haemorrhagic period.

Our research protocol was implemented in the treatment of 395 patients in the acute period following aneurysmal subarachnoid haemorrhage. Patients are classified as follows: Compensated (roughly Hunt and Hess I-II); Subcompensated (Hunt and Hess III); and Decompensated (Hunt and Hess IV-V). Only patients in the compensated state are deemed candidates for acute surgery. Patients presenting in the subcompensated or decompensated state undergo aggressive supportive treatment. Vasospasm is treated with balloon angioplasty as soon as the diagnosis is made; early interdiction of this process lowers the risk of neurologic deficit. A complex regimen of antifibrinolytic therapy is instituted; rebleeding rates have been reduced by 50% using a combination of heparin and aminocaproic acid. Ventriculostomy is performed in all decompensated patients. All intracranial haematomas with evidence of mass effect are immediately evacuated. Patients undergo craniotomy for aneurysm when their condition stabilizes in compensated state.

Adult↗

An antisense oligodeoxynucleotide-doxorubicin conjugate: preparation and its reversal multidrug resistance of human carcinoma cell line in vitro.

An antisense oligodeoxynucleotide-doxorubicin conjugate was synthesized by an aminocaproic acid linker. The synthetic conjugate was identified by HPLC analysis and UV-vis spectra. Properties of the conjugate in vitro conditions were investigated. The results demonstrated that the conjugate was remarkably stabilized by doxorubicin. When incubated in Dulbecco Phosphate-Buflered Saline (pH 7.4) at 37 degrees C, the conjugate was more stable than doxorubicin or the mixture of doxorubicin and antisense oligodeoxynucleotide. When incubated in 10% fetal serum at 37 degrees C, the conjugate showed a remarkable stabilization as compared to the unmodified oligodeoxynucleotide. Melting experiments demonstrated that the covalent attachment of doxorubicin strongly stabilized the binding of the oligodeoxynucleotide to its complementary sequence. In addition, in vitro reversion of multidrug resistance by the conjugate was assayed in a human carcinoma cell line (KB-A-1) resisting to doxorubicin. The result showed that the conjugate displayed very high reversal multdrug resistance activity in KB-A-1 cells in vitro. The conjugate lowered the IC50 value from 21.5 microM to 2.2 microM with a fold-reversal factor of 10. In contrast, a slight decrease of the IC50 value was observed when they combined with the "free" antisense oligodeoxynucleotide: the IC50 value was down from 21.5 microM to 16.8 microM. This study suggested that antisense oligodeoxynucleotide-doxorubicin conjugate might be helpful in multidrug resistance reversal.

Base Sequence↗

Degradation of extracellular matrix by mouse trophoblast outgrowths: a model for implantation.

During implantation the embryo attaches to the endometrial surface and trophoblast traverses the uterine epithelium, anchoring in the uterine connective tissue. To determine whether trophoblast can facilitate invasion of the uterus by degrading components of normal uterine extracellular matrix, mouse blastocysts were cultured on a radio-labeled extracellular matrix that contained glycoproteins, elastin, and collagen. The embryos attached to the matrix, and trophoblast spread over the surface. Starting on day 5 of culture there was a release of labeled peptides into the medium. The radioactive peptides released from the matrix by the embryos had molecular weights ranging from more than 25,000 to more than 200. By day 7 there were areas where individual trophoblast cells had separated from one another, revealing the underlying substratum that was cleared of matrix. When trophoblast cells were lysed with NH(4)OH on day 8, it was apparent that the area underneath the trophoblast outgrowth had been cleared of matrix. Scanning electron microscopy and time-lapse cinemicrography confirmed that the digestion of matrix was highly localized, taking place only underneath the trophoblast, with no evidence of digestion of the matrix beyond the periphery of the trophoblast outgrowth. The sharp boundaries of degredation observed may be due to localized proteinase secretion by trophoblast, to membrane proteinases on the surface of trophoblast, or to endocytosis. Digestion of the matrix was not dependent on plasminogen, thus ruling out a role for plasminogen activator. Digestion was not inhibited by a variety of hormones and inhibitors, including progesterone, 17beta-estradiol, leupeptin, EDTA, colchicine, NH(4)Cl, or epsilon-aminocaproic acid. This system of culturing embryos on extracellular matrix may be useful in determining the processes that regulate trophoblast migration and invasion into the maternal tissues during implantation.0

Animals↗

Some effects of proteolytic inhibitors on tissue injury and systemic anaphylaxis.

A study was made of the development of various forms of local and systemic injury in animals treated with inhibitors of proteolytic activity. The agents used were tosylarginine methyl ester (TAME), epsilon aminocaproic acid (EACA), and soybean trypsin inhibitor (SBTI). 1. Hemorrhagic necrosis in the skin of the rabbit following intradermal epinephrine in combination with bacterial endotoxin (either intravenous or local) was clearly suppressed by EACA, TAME, and SBTI, given systemically. Tosylarginine (TA) was ineffective. 2. No effect was observed on the classical Shwartzman reaction, the local Arthus phenomenon, or inflammation induced by xylene. 3. The lethal effects of systemic anaphylaxis in the mouse, acute endotoxemia in the rat and mouse, and drum shock in the rat are suppressed by EACA and TAME. 4. There was no effect on the generalized Shwartzman phenomenon in the rabbit and on anaphylaxis in the guinea pig. 5. The effects of EACA or TAME on the injury reactions under investigation were not due to a pharmacological or chemical action on vascular behavior per se. 6. The data provide corroborative evidence for a proteolytic step in injury phenomena which may be mediated through some common activation system. 7. The working hypothesis is advanced that local or systemic stress through the release of epinephrine may result in an increase of a circulating activator of proteolysis and that this in turn may give rise to the release of vasoactive substances,-possibly histamine, serotonin, or a polypeptide.

Anaphylaxis↗