Molecular weight estimation of proteins by electrophoresis in linear polyacrylamide gradient gels in the absence of denaturing agents.
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Biomedical subjects
Publications and source records attributed to P Lambin.
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Twenty cases of "asymptomatic" monoclonal gammopathies were detected by routine electrophoresis in patient's sera or in blood donors and were followed over 3-14 years. Four cases have shown a malignant evolution-two evolved toward Waldenström's macroglobulinemia after 3 years and two could be classified as myeloma 3 and 7 years, respectively, after detection of the monoclonal protein. The remaining cases were still "asymptomatic" 4 years later (7 cases), 7-9 years later (8 cases) and 14 years later (1 case). A malignant evolution occurred in approximately 20% of cases.
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A routine screening of monoclonal gammopathies (M.G.) was performed in the serum from 36, 015 blood donors by cellulose acetate electrophoresis. The incidence of M.G. was estimated to 0.14 per cent. About 86 per cent of cases can be classified as asymptomatic M.G. and 14 per cent as malignant M.G. (myeloma or Waldenström macroglobulinemia). In asymptomatic forms, heavy chain classes are only IgG or IgM with a large predominance of IgG (86,4%). It is suggested that donors in whom M.G. have been detected should not be allowed to give blood. A yearly clinical, hematological and an immunoglobulin check-up is recommended to these patients in order to defect the first sign of a malignant process.
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Inter-alpha-trypsin inhibitor was isolated from human plasma and submitted to proteolytic degradation by plasmin. A split product of low molecular weight (18 000 daltons) is obtained by gel filtration or solubilisation in perchloric acid. This fragment reacts with an anti-inter-alpha-trypsin inhibitor immune serum and migrates as beta1 globulins. Its specific activity against trypsin (after absorption of residual plasmin on sepharose lysine) was estimated to be 900 mU1/mg. Thus one molecule of fragment can inhibit one molecule of trypsin. As well with native protein as with its fragment, complexes formed with trypsin can be dissociated by urea or sodium dodecyl sulfate. This fragment is similar to the small molecular weight inhibitors obtained directly by solubilisation in perchloric acid from serum, urine and bronchial secretions.
The relatives of a 82 years old female patients with a Waldenstrom Macroglobulinemia were submitted to clinical and hematological investigations. A diclonal gammapathy (IgG kappa and IgG lambda) was found in the sister's serum and was related to a myeloma. A noticiable Bence Jones Proteinuria (light chain of lambda type) was equally found in serum and urines of the propositus brother but without any clinical or hematological evidence of myeloma. The examination of two other sisters of these patients does not reveal any immunological of hematological disorder. This new observation underlines the interest of a systematical investigation in the siblings of the patients with monoclonal gammapathies.
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The distribution in heavy chain classes and light chain types of M components were studied in 757 cases of monoclonal gammapathies. These gammapathies were classified according to clinical and hematological data in 439 myeloma (MM), 165 Waldenström's macroglobulinemia (WM) and 152 monoclonal gammapathies occurring in other conditions. The IgG/IgA ratio differs in myeloma and in non-myelomatous gammapathies (64% IgG versus 33% IgA in myeloma and 95% IgG versus 5% in absence of myeloma). Presence of free light chains in patient's urines (Bence Jones proteinuria) was detected in about 72% of cases of MM, 48% of WM and only in 9% in others gammapathies. Concerning the sex of patients, an equal repartition between males and females is observed in MM, whereas males predominate in WM. The age distribution of the patients shows that 74% of myeloma and 79% of WM were above sixty. In addition to the 757 cases under study, 10 sera with two M Components were characterized.
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Pure alpha2M is prepared with fresh plasma as starting material, to prevent the interaction of alpha2M from proteolytic enzymes of plasma such as thrombin, plasmin and kallikrein. During the purification steps, polybrene and aprotin are used as inhibitors and plasminogen is absorbed onto bentonite. When alpha 2M is submitted to polyacrylamide gel electrophoresis (PAA) containing 0.1% SDS, a complete dissociation in two half-molecules of MW 380,000 occurs. When alpha2M is incubated in 1% SDS and 1% beta-mercaptoethanol as reducing agent, only one component of MW 190,000 is observed in PAA-SDS. This experiments show that the alpha2M molecule consist of two symetric halves of same MW (380,000) linked by non covalent bonds. Each two-half-molecules is made of two polypeptides chains MW 190,000 linked by disulfide bonds. Thus alpha2M molecule contains four polypeptides chains having a same MW. The same techniques were applied to the study of alaph2M proteinases complexes. Three different proteinases (plasmin, trypsin and papain) were used in these experiments. Trypsin and papain are commercialy available. Plasminogen was obtained by affinity chromatography and activated into plasmin by insoluble streptokinase fixed on PAB cellulose.
Inter-alpha-trypsin inhibitor (I alpha I) has been purified from C.N.T.S. fraction III as starting material. The purification procedure includes D.E.A.E. cellulose chromatography and gel filtration on G 150 Sephadex in the presence of EDTA. The purified protein gives one precipitation line in immunoelectrophoresis against anti-whole human sérum. It reacts only with an anti I alpha I immune serum and possesses a strong antitryptic activity. When studied in starch or polyacrylamide gel electrophoresis 2 components are observed, each of them having the same antigenic structure and the same antitryptic activity as the crude preparation. The slower and less important component is dissociated by 0,1% SDS. The molecular weight estimation of I alpha I BY PAA/SDS is about 180,000. This result is not modified by the presence of 1% beta mercaptoethanol indicating that I alpha I consists of one polypeptide chain. Crude preparation reveals under the same electrophoretical conditions small amounts of low molecular weight components (135,000 52,000 and 26,000) which can be due to a proteolytic action on I alpha I. Indeed plasmin is able to produce such fragments having an antitryptic activity as shown by fibrin/polyacrylamide gel electrophoresis. The relationship between small molecular weight inhibitors of human serum and bronchial secretions and those obtained after degradation of I alpha I by plasmin is discussed.
Routine screening of monoclonal gammapathies (M.G.) was performed on the serum of 13,914 blood donors by cellulose acetate electrophoresis. Twenty-six cases of M.G. were detected corresponding to a frequency of 0.19 per cent. The incidence of the M.G. progresses with increasing age comparatively to the age distribution of the blood donors under investigation. Most of the M.G. detected can be classified as "asymptomatic" M.G. (23 of the 26) and heavy chain classes are only IgG or IgM with a large predominance of IgG class (about 90%). It is suggested that donors in whom M.G. have been detected should not be eligible for blood donation. A yearly clinical, hematologic and immunoglobulin checkup is recommended for these patients in order to detect a possible malignant transformation.