Permeability of Cortical Bone to Large Molecular Weight Proteins Under Diffusive and Load-Induced Convective Transport Mechanisms

Advances in Bioengineering ◽

10.1115/imece2004-61923 ◽

2004 ◽

Author(s):

R. B. Patel ◽

A. E. Tami ◽

M. L. Knothe Tate

Keyword(s):

Molecular Weight ◽

Fluid Flow ◽

Cortical Bone ◽

Molecular Size ◽

Convective Transport ◽

Transport Mechanisms ◽

Quantitative Evidence ◽

Macromolecular Transport ◽

Large Molecular Weight ◽

Poroelasticity Theory

The composition of bone is 75% mineral and organic components and 25% fluid; yet until the past 30 years, the fluid component of bone had been ignored [1]. The idea of load induced fluid flow via pressure gradients was hypothesized for the first time by Piekarski et al in his application of Biot’s poroelasticity theory [2]. Poroelasticity theory mathematically describes the sponge-like behavior of bone: when bone is squeezed(loaded) fluid will be induced to flow. However although the concept of load induced fluid flow is well accepted in the orhopedic field, our study is the first to provide quantitative evidence of the effect of load induced fluid on macromolecular transport. Hence the goals of this study include observing permeability of large molecular weight tracers in cortical bone, ii.) comparing molecular size dependence on tracer permeability in cortical bone, and iii.) comparing effects of convective and diffusive transport mechanisms on permeability.

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Biliary obstruction dissipates bioelectric sinusoidal-canalicular barrier without altering taurocholate uptake

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1989.256.2.g312 ◽

1989 ◽

Vol 256 (2) ◽

pp. G312-G318

Author(s):

J. Cotting ◽

T. Zysset ◽

J. Reichen

Keyword(s):

Molecular Weight ◽

Biliary Obstruction ◽

Molecular Size ◽

Base Line ◽

Hepatic Extraction ◽

Short Term ◽

Extrahepatic Cholestasis ◽

Large Molecular Weight ◽

Unidirectional Transfer

To study immediate events during extrahepatic cholestasis, we investigated the effect of short-term biliary obstruction on the bioelectrical sinusoidal-canalicular barrier in the rat using molecular weight-matched uncharged and negatively charged inert solute pairs. The bioelectrical barrier averaged -22 +/- 5 and -18 +/- 4 mV (NS) using the pair carboxy-/methoxyinulin and ferrocyanide/sucrose, respectively. After a 20-min biliary obstruction both decreased by 61 and 11%, respectively, but only the large molecular weight pair (the inulins) returned to base line after release of the obstruction. Inert solute clearances were increased after short biliary obstruction depending on molecular size and negative charge (ferrocyanide greater than sucrose greater than carboxyinulin greater than inulin), suggesting that both permeability and bioelectrical barriers were affected by obstruction. The hepatic extraction in vivo of a passively transported drug not excreted into bile (D-propranolol) was not affected by obstruction, whereas that of an actively transported drug (glycocholate) decreased from 66 +/- 8 to 41 +/- 20% during biliary obstruction (P less than 0.01). Unidirectional transfer of glycocholate was not affected by short-term biliary obstruction in the situ perfused rat liver; however, 2 min after [14C]glycocholate administration, increased return was observed in hepatic venous effluent in obstructed animals. Our findings demonstrate a loss of the bioelectrical barrier immediately after short-term biliary obstruction. Decreased hepatic extraction in the view of unaltered sinusoidal uptake demonstrates regurgitation of bile into blood during short-term biliary obstruction.

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Fibrin and Fibrinogen Proteolysis Products: Comparison between Gel Filtration and SDS Polyacrylamide Electrophoresis Analysis

Thrombosis and Haemostasis ◽

10.1055/s-0038-1651859 ◽

1977 ◽

Vol 38 (02) ◽

pp. 0524-0535 ◽

Cited By ~ 14

Author(s):

Norma Alkjaersig ◽

Andrew Davies ◽

Anthony Fletcher

Keyword(s):

Molecular Weight ◽

Analytical Methods ◽

Gel Filtration ◽

Molecular Size ◽

The Other ◽

Reaction Products ◽

Human Fibrinogen ◽

Polyacrylamide Electrophoresis ◽

Large Molecular Weight ◽

Stabilized Fibrin

SummaryThe proteolysis of purified human fibrinogen, stabilized and non-stabilized fibrin by plasmin were investigated by gel filtration analysis and SDS polyacrylamide electrophoresis of the reaction products. Plasmin proteolysis of fibrinogen followed the sequential steps previously reported and the two analytical methods yielded concordant results. Large molecular weight proteolysis products, of substantially greater molecular weight than native fibrinogen, were identified by gel filtration analysis following dissolution of stabilized and non-stabilized fibrin clots; with further incubation with plasmin, these proteolysis products gradually diminished in size. On the other hand, SDS polyacrylamide electrophoresis of these fibrin digests demonstrated that while non-stabilized fibrin yielded breakdown products similar in size to those obtained after proteolysis of fibrinogen, stabilized fibrin digests showed moieties of greater molecular size estimated to be of molecular weight 400,000 to 800,000. The final breakdown products of stabilized fibrin differed from those of fibrinogen and nonstabilized fibrin in that fragment D was present in the “double D” cross-linked form.

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Fibrin and Fibrinogen Proteolysis Products: Comparison Between Gel Filtration and SDS Polyacrylamide Electrophoresis Analysis

10.1055/s-0039-1682462 ◽

1977 ◽

Author(s):

N. Alkjaersig ◽

A. Davies ◽

A. Fletcher

Keyword(s):

Molecular Weight ◽

Analytical Methods ◽

Gel Filtration ◽

Molecular Size ◽

The Other ◽

Reaction Products ◽

Human Fibrinogen ◽

Polyacrylamide Electrophoresis ◽

Large Molecular Weight ◽

Stabilized Fibrin

The proteolysis of purified human fibrinogen, stabilized and non-stabilized fibrin by plasmin were investigated by gel filtration analysis and SDS Polyacrylamide electrophoresis of the reaction products. Plasmin proteolysis of fibrinogen followed the sequential steps previously reported and the two analytical methods yielded concordant results. Large molecular weight proteolysis products, of substantially greater molecular weight than native fibrinogen, were identified by gel filtration analysis following dissolution of stabilized and non-stabilized fibrin clots; with further incubation with plasmin, these proteolysis products gradually diminished in size. On the other hand, SDS Polyacrylamide electrophoresis of these fibrin digests demonstrated that while non-stabilized fibrin yielded breakdown products similar in size to those obtained after proteolysis of fibrinogen, stabilized fibrin digests showed moieties of greater molecular size estimated to be of molecular weight 400, 000 to 800, 000. The final breakdown products of stabilized fibrin differed from those of fibrinogen and non-stabilized fibrin in that fragment D was present in the “double D” cross-linked form.

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The External Shape of Human γ GI Immunoglobulin from Crystal Sections

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010006619x ◽

1971 ◽

Vol 29 ◽

pp. 428-429

Author(s):

L. W. Labaw

Keyword(s):

Molecular Weight ◽

Sodium Phosphate ◽

Osmium Tetroxide ◽

Unit Cell ◽

Monoclinic Space Group ◽

X Ray ◽

Large Molecular Weight ◽

Cell Dimensions ◽

Unit Cell Dimensions ◽

Crystallographic Axes

Crystals of a human γGl immunoglobulin have the external morphology of diamond shaped prisms. X-ray studies have shown them to be monoclinic, space group C2, with 2 molecules per unit cell. The unit cell dimensions are a = 194.1, b = 91.7, c = 51.6Å, 8 = 102°. The relatively large molecular weight of 151,000 and these unit cell dimensions made this a promising crystal to study in the EM.Crystals similar to those used in the x-ray studies were fixed at 5°C for three weeks in a solution of mother liquor containing 5 x 10-5M sodium phosphate, pH 7.0, and 0.03% glutaraldehyde. They were postfixed with 1% osmium tetroxide for 15 min. and embedded in Maraglas the usual way. Sections were cut perpendicular to the three crystallographic axes. Such a section cut with its plane perpendicular to the z direction is shown in Fig. 1.This projection of the crystal in the z direction shows periodicities in at least four different directions but these are only seen clearly by sighting obliquely along the micrograph.

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Suppressive Effect of Dextran on Platelet Adhesiveness

Thrombosis and Haemostasis ◽

10.1055/s-0038-1655597 ◽

1966 ◽

Vol 16 (03/04) ◽

pp. 384-394 ◽

Cited By ~ 32

Author(s):

S Cronberg ◽

B Robertson ◽

Inga Marie Nilsson ◽

J.-E Niléhn

Keyword(s):

Molecular Weight ◽

Bleeding Time ◽

Slight Modification ◽

Molecular Size ◽

Suppressive Effect ◽

Factor Ix ◽

Factor V ◽

Platelet Adhesiveness ◽

History Of ◽

Mean Molecular Weight

Summary43 normal volunteers, 3 patients with thrombophlebitis, and 1 patient with a high platelet adhesiveness and a history of thrombophlebitis have received dextran and its action on the mechanism of haemostasis has been studied. Platelet adhesiveness has been investigated by a slight modification of Hellem’s methods for whole blood and plasma. Dextran with a mean molecular weight of 70,000 produced a markedly lowered platelet adhesiveness together with a moderate prolongation of the Ivy bleeding time. Factor VIII was decreased by about 50% and factor V, factor IX and fibrinogen were decreased slightly more than could be expected from haemodilution alone. No fibrinolysis occurred. Dextran of lower molecular size was less potent. The possible use of dextrans as a thrombosis prophylactic agent is discussed.

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