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Biomedical subjects

J R Shainoff

Publications and source records attributed to J R Shainoff.

At least 37 records · Page 2Linked to original sources
PubMed1990

Effects of cross-linking on clearance of circulating alpha-fibrin monomer and its complexes.

Preceding studies showed that fibrin-monomer of the type lacking only fibrinopeptide A (alpha-fibrin) cleared from the circulation more rapidly than a tighter aggregating form of monomer that lacks both fibrinopeptides A and B (alpha beta-fibrin). The rapid clearance of alpha-fibrin may be related to the high dissociability of the soluble complexes that it forms with fibrinogen in blood. In this study, we use cross-linking by factor XIIIa to suppress dissociation of fibrin complexes and examine the effect of the cross-linking on the circulatory half-life of the fibrin. Incubation of alpha-fibrin-monomer/fibrinogen solutions with factor XIIIa before injection in rabbits increased the circulatory half-life of the fibrin (range, 2 to 16 hours) in proportion to the percentage conversion of monomer to cross-linked dimers and small oligomers. Electrophoretic analyses of plasma samples confirmed that, compared with non-cross-linked monomer, cross-linked dimers and small oligomers were long lived and, further, were not degraded. The inhibition of clearance through cross-linking occurs only under conditions that produce partial cross-linking of the fibrin. An opposite effect occurs when cross-linking is allowed to approach completion, as a result of polymerization of the fibrin into large fibers that disappear almost immediately after injection. Cross-linking elicited in vivo with injected factor XIIIa has an inhibitory effect on clearance of injected monomer similar to the effect produced by partial cross-linking in vitro. It is proposed that the prolonged survival of cross-linked dimers and small oligomers in the circulation provides a partial explanation for the frequent prevalence of cross-linked rather than non-cross-linked complexes in blood of human subjects with vascular disease.

Animals↗
PubMed1990

Fibrinogen A alpha and gamma-chain dimers as potential differential indicators of atherosclerotic and thrombotic vascular disease.

Cross-linked fibrin(ogen) dimers are known to be elevated in the plasma of subjects with occlusive vascular disease, and are thought to be fibrin dimers. Immunoelectrophoretic analyses of the dimers, however, indicate that (1) they are predominantly fibrinogen rather than fibrin dimers, and (2) they contain cross-linked A alpha-chains (A alpha-dyads) instead of the gamma-chain dyads that are rapidly formed by factor XIII during blood coagulation. Furthermore, the mobilities of the A alpha-dyads differ from the cross-linked alpha-chain products that accompany the gamma-chain cross-linking by factor XIII. Instead, the mobilities coincide with the distinct A alpha-dyads that are produced by tissue transglutaminase, an intracellular enzyme not normally present in plasma. The intimal fibrinogen deposits in atherosclerotic aortas also possess fibrinopeptide A and cross-linked A alpha-chains. Thus, both the plasma fibrinogen dimers and the intimal fibrinogen deposits appear to derive from the action of released tissue transglutaminase more so than factor XIII. It is proposed that, in the absence of other indications of cytolytic processes, the levels of A alpha-dyads in plasma reflect ongoing cellular injury accompanying atherogenesis. The extent to which gamma-dyads accompany the A alpha-dyads may signal progression of the disease to advanced stages in which ulcerations and occlusive lesions trigger thrombotic complications.

Arteriosclerosis↗
PubMed1989

Malignant hypertension, fibrinoid deposition, and fibrinogen electrophoresis.

Electrophoretic profiles of the molecular weight distributions of fibrinogen derivatives in blood provide a tool for combined assessment of coagulation and fibrinolysis in the course of vascular disease. Profiles obtained in studies on an experimental model of hypertension and in humans with occlusive vascular disease are discussed. In the experimental studies elevations in the level of cross-linked dimers provided a more reliable means for predicting development of malignant hypertension than did many other criteria, especially near the outset when blood pressure changed to similar degrees in rats with malignant and benign hypertension. Similarly, we find that levels of dimeric and occasionally trimeric forms of fibrinogen are more prominently elevated than degraded forms of fibrinogen in patients with occlusive vascular disease.

Animals↗
PubMed1987

Studies on the ultrastructure of fibrin lacking fibrinopeptide B (beta-fibrin).

Release of fibrinopeptide B from fibrinogen by copperhead venom procoagulant enzyme results in a form of fibrin (beta-fibrin) with weaker self-aggregation characteristics than the normal product (alpha beta-fibrin) produced by release of fibrinopeptides A (FPA) and B (FPB) by thrombin. We investigated the ultrastructure of these two types of fibrin as well as that of beta-fibrin prepared from fibrinogen Metz (A alpha 16 Arg----Cys), a homozygous dysfibrinogenemic mutant that does not release FPA. At 14 degrees C and physiologic solvent conditions (0.15 mol/L of NaCl, 0.015 mol/L of Tris buffer pH 7.4), the turbidity (350 nm) of rapidly polymerizing alpha beta-fibrin (thrombin 1 to 2 U/mL) plateaued in less than 6 min and formed a "coarse" matrix consisting of anastomosing fiber bundles (mean diameter 92 nm). More slowly polymerizing alpha beta-fibrin (thrombin 0.01 and 0.001 U/mL) surpassed this turbidity after greater than or equal to 60 minutes and concomitantly developed a network of thicker fiber bundles (mean diameters 118 and 186 nm, respectively). Such matrices also contained networks of highly branched, twisting, "fine" fibrils (fiber diameters 7 to 30 nm) that are usually characteristic of matrices formed at high ionic strength and pH. Slowly polymerizing beta-fibrin, like slowly polymerizing alpha beta-fibrin, displayed considerable quantities of fine matrix in addition to an underlying thick cable network (mean fiber diameter 135 nm), whereas rapidly polymerizing beta-fibrin monomer was comprised almost exclusively of wide, poorly anastomosed, striated cables (mean diameter 212 nm). Metz beta-fibrin clots were more fragile than those of normal beta-fibrin and were comprised almost entirely of a fine network. Metz fibrin could be induced, however, to form thick fiber bundles (mean diameter 76 nm) in the presence of albumin at a concentration (500 mumol/L) in the physiologic range and resembled a Metz plasma fibrin clot in that regard. The diminished capacity of Metz beta-fibrin to form thick fiber bundles may be due to impaired use or occupancy of a polymerization site exposed by FPB release. Our results indicate that twisting fibrils are an inherent structural feature of all forms of assembling fibrin, and suggest that mature beta-fibrin or alpha beta-fibrin clots develop from networks of thin fibrils that have the ability to coalesce to form thicker fiber bundles.

Blood Coagulation↗
PubMed1985

Kinetic characterization of a saturable pathway for rapid clearance of circulating fibrin monomer.

The mechanism of clearance of circulating fibrin monomer was investigated in rabbits through (1) study of decay in plasma concentrations of 125I-labeled monomers with variant fibrinopeptide content and (2) concurrent analysis of decay of the monomers relative to coinjected 131I-fibrinogen. Under the conditions employed, essentially all of the fibrin became distributed in a soluble form in plasma and decayed independently of the coinjected fibrinogen. Among the species of fibrin studied, monomer lacking fibrinopeptide A alone (alpha-fibrin) underwent very rapid clearance by a saturable mechanism that was not evident in relatively sluggish clearance of monomer lacking either fibrinopeptide B alone (beta-fibrin) or both fibrinopeptides A and B (alpha beta-fibrin). Decay of alpha-fibrin conformed with a kinetic mechanism involving first-order permeation of the fibrin into extravascular space at a rate equivalent to that of permeation of fibrinogen; unlike fibrinogen, however, the alpha-fibrin underwent immediate absorption in parallel with permeation (t1/2 = 2.6 hours) at doses below an apparent saturating level of 3 mg/kg. At doses near the absorptive limit, the uptake accompanying permeation diminished as in a second-order kinetic mechanism, and at very high doses the plasma decay of the alpha-fibrin approached that of fibrinogen. The beta- and alpha beta-fibrins also permeated extravascular space in parallel with fibrinogen, but absorption proceeded sluggishly (t1/2 = 11 and 16 hours, respectively) at low doses and did not change with increasing dose. The uniquely rapid and saturable clearance of alpha-fibrin is suggested to involve uptake through the fibrin aggregation site that is blocked by fibrinopeptide A in fibrinogen and beta-fibrin and by tight binding to fibrinogen in soluble complexes formed by alpha beta-fibrin. A corollary of this hypothesis is that rapid uptake depends on dissociability of fibrin complexes for access to the aggregation site, a mechanism that is just the converse of uptake through aggregation.

Animals↗
PubMed1983

Fibrinopeptide B in fibrin assembly and metabolism: physiologic significance in delayed release of the peptide.

The delayed release of peptide B that accelerates towards the end of fibrin formation unmasks accessory (b-) epitopes for monomer interaction. Ultracentrifuge and chromatographic analysis of the composition and dissociation of soluble complexes formed by monomers in fibrinogen solution indicate that the b-epitope augments aggregation by acting cooperatively with the a-epitope to reinforce rather than cross-bridge oligomer assembly. Monomer/fibrinogen association by coordinated interactions through both epitopes is strengthened by an additional order of magnitude over associations (10(7) and 1.6 X 10(6) M-1) through the a- and b-epitopes individually, without affecting oligomer thickness. It is suggested that the delayed release of B has purpose in allowing early complexes to dissociate for (1) rapid equilibration across interstitial fluids, and for (2) rapid uptake by phagocytic cells which depend on access to the a-epitope for monomer absorption. In late stages of coagulation, stabilization of oligomer assembly imparted by the b-epitope blocks both equilibration of fibrin concentrations and phagocytic clearance of the fibrin to localize deposition.

Chromatography, Gel↗
PubMed1983

Acute arterial fibrinoid deposition and ischaemic parenchymal damage of the kidney. Pathogenic factors in the development of malignant hypertension.

The development and evolution of hypertensive vascular lesions affecting the arterial supply of (a) the kidney and (b) organs other than the kidney were studied in rats developing either malignant (MHY) or benign (BHY) hypertension 3, 6, 9 and 12 days after aortic ligation between the renal arteries. Vascular disease evolved into two distinct patterns which suggested acute renal damage to be the determinant for the development of either the malignant or benign form of hypertension. Three days after aortic ligation MHY and BHY animals showed widespread fibrinoid deposition in vascular territories above the aortic ligature. However, in MHYs these lesions were much more severe and, in the kidney, they were accompanied by the development of focal parenchymal atrophy, microinfarcts and hyalin droplet degeneration of cells of the Bowman capsule. The degree of renal damage correlated with elevations in blood urea nitrogen (BUN) and plasma creatinine; however, there was no correlation with rises in blood pressure, plasma renin activity (PRA), aldosterone or corticosterone which were similarly elevated in 3-day MHY and 3-day BHY animals. Between 6 and 12 days a marked clearance of fibrinoid took place in all organ beds of BHYs, but in the non-renal vasculature of MHY animals fibrinoid remained prominent and served as the central core for necrotising arterial lesions. In the kidney of MHYs some reduction in the fibrinoid content was observed, but the parenchymal damage perpetuating from the earlier stages had exacerbated leading to collagen deposition and a marked increase in the collagen concentration of the renal cortex. These features were accompanied by further elevations in PRA and corticosteroids and a progressive deterioration of renal function. By contrast, in 12-day BHY animals, despite sustained hypertension, PRA and corticosteroids were falling from their previously higher levels and normal renal function was maintained. These studies warrant inference that extensive parenchymal damage of the kidney due in part to severe arterial fibrinoid deposition is one of the initial events in the development of malignant hypertension.

Aldosterone↗
PubMed1982

Adsorptive endocytosis of fibrin monomer by macrophages: evidence of a receptor for the amino terminus of the fibrin alpha chain.

Human fibrinogen and fibrin monomer were labeled with heme-octapeptide for cytochemical examination of their interaction with rabbit peritoneal macrophages in vitro. Upon short exposure to labeled fibrin monomer in solution with unlabeled fibrinogen, the cells became covered with surface-adsorbed monomer in nonaggregated form and having a characteristic trinodular shape. Within 30 min, the adsorbed monomer became fully internalized by vesicular uptake, with much of it being incorporated into lysosomal bodies. A concomitant loss of adsorptive capacity of the cell surface for uptake of more monomer accompanied the internalization. By contrast, labeled fibrinogen was not adsorbed by the macrophage surface. Some internalization of fibrinogen by passive fluid-phase pinocytosis was evident, but it was not accompanied by loss of absorptive capacity for fibrin monomer. The active uptake of monomer may have depended on binding to the amino terminus that is blocked by fibrinopeptide A in fibrinogen, because addition of synthetic peptide corresponding to the terminal Gly-Pro-Arg segment inhibited both the adsorption and the internalization of monomer.

Endocytosis↗
PubMed1981

Cascade immunoelectrophoresis: combined electrophoretic and solid-phase processing of immunoreactive protein by zonal immobilization.

A new approach to immunochemical analysis of complex mixtures of proteins has been devised through development of a system for (1) sequentially absorbing, desorbing, and cascading antibodies in a profile indicative of both the quantity and electrophoretic characteristics of the antigen, and (2) for carrying out multiple tests of antigenic determinants at sub-picomole levels regardless of the solubility or precipitin forming characteristics of the immunoreactive protein. The procedure employs zonal immobilization in which a novel, aldehyde-rich gel (glyoxyl agarose) is used interchangeably as an inert support for electrophoresis and as an immobilizing matrix to fix the protein for analysis by solid-phase techniques. Proteins may be separated on the gel as with ordinary agarose, and then driven to combine covalently with the gel upon exposure to NaCNBH3. After removing NaCNBH3, the distribution of specified antigens is then established by exposing the gel to antibody an profiling the pattern of antibody uptake by a cross-electrophoretic technique in which the absorbed antibody is (1) desorbed with dodecyl sulfate, then (2) transferred through a gel containing potassium ion to halt migration of the detergent, and (3) displayed by immunoprecipitation with anti-IgG antibodies. To cascade the process further, the IgG may be immobilized and used as a surrogate antigen to bind additional antibody protein. In addition to enhancing sensitivity, the cross-electrophoretic measurement of uptake of antibody by immobilized antigen eliminates dependence on direct immunoprecipitation of the antigen, and may accordingly be of particular advantage with non-precipitin forming antigens and monoclonal antibodies.

Aldehydes↗
PubMed1980

Factor VIII-related protein circulates in normal human plasma as high molecular weight multimers.

The size of human factor VIII-related protein in plasma has been determined by sodium dodecyl sulfate (SDS) glyoxyl agarose electrophoresis. The protein was immobilized after the electrophoresis by coupling it to the modified agarose, and it was identified by autoradiography using purified rabbit anti-factor VIII-related antigen (VIIR:Ag). A series of multimeric forms was identified with Mr of 0.85-12 x 10(6). The distribution of VIIR:Ag multimers was the same in heparin and citrate anticoagulated plasmas and in serum, and the pattern was the same after freezing as in plasma kept at 37 degrees C from the time of venipuncture until the electrophoresis was complete. These observations indicate that VIIR:Ag circulates in normal plasma as a population of very large multimers and that the size distribution is not an artifact induced by purification methods, freezing, or calcium chelation.

Animals↗
PubMed1979

Fibrinopeptide B and aggregation of fibrinogen.

Removal of fibrinopeptide B from human fibrinogen by reaction with the procoagulant enzyme from copperhead snake venom below 25 degrees C resulted in tight aggregation of the fibrinogen, which, in turn, progressively blocked a concomitant but sluggish release of fibrinopeptide A by the enzyme. When the clots obtained at less than 25 degrees C were warmed, they dissociated into soluble aggregates and monomers. Release of fibrinopeptide A then resumed, and a secondary coagulation followed. The aggregation induced by release of fibrinopeptide B itself involves a plasmin-susceptible segment located just distal to B in the B beta chain of fibrinogen, a segment previously shown to be of little importance in the aggregation induced by release of fibrinopeptide A.

Amino Acid Sequence↗
PubMed1976

Isolation and characterization of a dog serum lipoprotein having apolipoprotein A-I as its predominant protein constituent.

The serum high density lipoproteins (HDL) of normolipemic dogs (beagles) were isolated in the density range of p 1.063 to 1.21 g/ml, and characterized in terms of composition and physical properties (flotation and diffusion coefficients, partial specific volume, molecular weight, electrophoretic mobility, ultraviolet absorption, and circular dichroism). The results indicated that canine HDL is a relatively homogeneous class with a molecular weight of about 230 000 and general properties similar to those reported for human HDL. After delipidation, the resulting apolipoprotein, apo-HDL, was fractionated by Sephadex G-200 column chromatography in urea or guanidine hydrochloride solutions. About 90% of the apo-HDL consisted of a protein with a molecular weight of about 28 000, similar in amino acid composition to human apolipoprotein A-I and having the same NH2 terminus (aspartic acid) and COOH terminus (glutamine) and no carbohydrates. Two other proteins were isolated, one having an apparent mol wt of 55 000 and representing, at least in part, an aggregate of apolipoprotein A-I and the other component with a mol wt of 8000, not yet characterized. The results indicate that canine HDL, as an intact complex, has general physical properties that lie between those reported for human HDL2 and HDL3, and that it differs compositionally from the human products mainly in its predominant content of apo-A-I. These findings together with evidence for the relatively homogeneous nature of the canine HDL provide new prospects for unraveling the relationship between polypeptide composition and HDL structure.

Amino Acids↗
PubMed1975

Microangiopathic hemolytic anemia in renal allotransplantation. Repart of a successfully treated case and review of the literature.

The development of microangiopathic hemolytic anemia after renal transplantation in a 17 year old white boy is reported, and the literature is reviewed. In this patient microangiopathic hemolytic anemia developed 6 weeks after renal transplantation during a second episode of rejection. Light, fluorescence and electron microscopy demonstrated the renal vascular lesion associated with this syndrome. In contrast to the other four previously reported cases of microangiopathic hemolytic anemia associated with renal allotransplantation, this patient had complete resolution of the microangiopathic hemolytic anemia with heparin therapy and improved allograft function, presumably with diminution of the vascular lesion. He survived a complicated early period after renal transplantation and has shown no recurrence of microangiopathic hemolytic anemia in the 18 months since transplantation. Special red blood cell and fibrinogen studies are discussed.

Adolescent↗