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PubMed1999

Genetic association of alpha2-macroglobulin with Alzheimer's disease in a Finnish elderly population.

Recently, two studies have reported an association between the alpha2-macroglobulin gene on chromosome 12 and late-onset Alzheimer's disease, whereas others have not been able to replicate these findings. By using a prospective population-based study, we have investigated the relation between two polymorphisms in this gene with the presence of the disease and also with the extent of pathological changes in the cerebral cortex. The Vantaa 85+ Study includes all 601 persons, at least 85 years of age, who were living in Vantaa, Finland, on April 1, 1991. The neocortical beta-amyloid protein load and the number of neurofibrillary tangles were determined on tissue sections by using methenamine silver staining and a modified Bielschowsky staining, respectively. The A/A genotype in exon 24 of the alpha2-macroglobulin gene was associated with neuropathologically defined diagnosis of Alzheimer's disease according to the CERAD (Consortium to Establish a Registry for Alzheimer's Disease) criteria and with an increase in the neocortical beta-amyloid protein load. The effect of this association was stronger in the apolipoprotein E epsilon4-negative group. Therefore, genetic variability in the alpha2-macroglobulin gene is a risk factor associated with neuropathologically defined Alzheimer's disease in our population, as well as with the extent of neocortical beta-amyloid protein deposition.

Adult↗

PubMed1997

[The activity of alpha-2 macroglobulin in the blood of patients with prostatic carcinoma].

The activity of alpha 2-macroglobulin in the blood of the patients with prostatic carcinoma (PC) and benign prostatic hyperplasia (BPH) was examined. It was shown an decrease of alpha 2-macroglobulin in patients with prostatic carcinoma in comparison with control group consisted of the patients with benign prostatic hyperplasia. The low activity of alpha 2-macroglobulin in the blood od the patients with PC can be a symptom of an increase risk of haemorrhagic complications.

Aged↗

PubMed2000

[Levels of alpha-2-macroglobulin in blood serum of women giving birth to hypotrophic and eutrophic newborns].

We tested the concentration of alpha-2-macroglobulin in sera of 33 women bearing eutrophic newborns, 36 women bearing hypotrophic newborns and 30 healthy not pregnant women in reproductive age. The concentration of this inhibitor was measured using radial immunodiffusion method according to Mancini et al. We found distinct decrease of alpha-2-macroglobulin concentration in sera of bearing women. In women bearing eutrophic newborns we found 154 mg/dl, in women bearing hypo-trophic newborns 171 mg/dl whereas in controls 250 mg/dl. We have noted statistically significant differences between tested groups to controls and between investigated groups. Taking under consideration the role of alpha-2-macroglobulin as the modulator of immune system as well as the activity of several cytokins, therefore one can suppose that alpha-2-M may affect on cellular growth developed foetus in intrauterine.

Adult↗

PubMed2001

A study of plasma alpha-2-macroglobulin levels in type 2 diabetic subjects with microalbuminuria.

BACKGROUND: Alpha-2 macroglobulin (Alpha-2-M) is a major plasma protease inhibitor that also regulates the activity of a variety of bioactive peptides including interleukins and exerts a range of immunomodulatory effects. OBJECTIVE: We conducted the present study with the objective to study the alpha-2-M levels in type 2 diabetic subjects with microalbuminuria in an attempt to establish alpha-2-M as a predictor of microvascular complications in diabetes. MATERIAL AND METHODS: Plasma Alpha-2-M levels were assayed in 100 (53 males and 47 females) randomly selected type 2 diabetic subjects with microalbuminuria. Diabetes was diagnosed according to the expert committee report of 1998. Patients with any acute metabolic complication like hypoglycemia, ketoacidosis, cerebrovascular accident or any acute infection were not included in the study group. RESULTS: Majority of patients belonged to 40-60 years age group. In our study alpha-2-M levels indicated a clear increase in diabetic subjects with the increasing age of subjects confirmed by multiple logistical analysis. Alpha-2-M levels were not found to be significantly different between males and females (55.6 +/- 11.3 vs. 53.7 +/- 10.5). Duration of diabetes was found to be an important confounding variable showing a direct positive correlation with alpha-2-M levels and also a significant correlation was found between alpha-2-M levels with different levels of microalbuminuria on multiple logistical analysis. No significant relation of alpha-2-M levels with either fasting blood sugar or HbA1 was observed. CONCLUSION: The increase in plasma alpha-2 macroglobulin levels in diabetes may be a correlative measure to encounter the potential proteolytic challenge associated with diabetic microangiopathy, even very early in the course of the disease. Alph-2 macroglobulin may yet be one of the most specific markers of microvascular complications in diabetes than any other serum protein.

Aged↗

PubMedDate not supplied

[Alpha2-macroglobulin gene polymorphism in patients with Alzheimer's disease].

Recent studies suggest that alpha 2-macroglobulin (alpha 2 m) may play a role in the pathogenesis of Alzheimer's Disease (AD). The presence of alpha 2-macroglobulin G/G genotype is thought to increase the risk of AD. The aim of the study was to analyse alpha 2 m polymorphism in two groups: AD patients (n = 60, F = 41, M. = 19, mean age 73.3 +/- 6.3) and non-demented control group (n = 58, F = 36, M. = 22, mean age 73.1 +/- 8.3, mean MMSE score 27). Frequencies of genotypes A/A, A/G, G/G in AD group were: 0.46: 0.42: 0.12. In control group those frequencies were: 0.40: 0.48: 0.12. The lack of statistically significant difference between G/G frequencies in both groups of patients may suggest that alpha 2-macroglobulin G/G genotype is not a risk factor for AD.

Aged↗

PubMed1992

Isolation and characterization of alpha 2-macroglobulin-protease complexes from purified mouse mammary tumor virus and culture supernatants from virus-infected cell lines.

Cleavage of oligopeptide substrates mimicking the maturation sites in the Gag polyproteins of the mouse mammary tumor virus was assayed using lysed virus. Cleavage at the expected P1-P1' positions was detected in four of seven synthetic peptides. However, studies with specific inhibitors of retroviral proteases showed that only two of them could be unequivocally attributed to the viral enzyme. In an attempt to characterize other proteolytic activities that copurify with the virus, we isolated a multicatalytic high molecular mass protease (700 kDa) that copurifies with the virus. This protein has been identified as an alpha 2-macroglobulin-protein complex according to its biochemical properties and ultrastructure. The proteases forming these complexes are mainly serine proteases and can be inhibited by phenylmethylsulfonyl fluoride. However, other compounds such as chymostatin and elastatinal are more effective inhibitors. The relative efficacy of each compound depends on the substrate, since the complexes described herein appear to be multicatalytic. Elastatinal is a very good inhibitor of the cleavages found at Ala-Ala bonds in peptides representing the capsid/nucleocapsid site, while chymostatin inhibits certain cleavages at the carboxyl terminus of bonds involving leucine and valine in three of the substrates used. Therefore, the alpha 2-macroglobulin present in the cell culture medium is able to bind proteases, forming high molecular weight complexes, which are active against peptide substrates, copurify with the virus and are responsible for the nonviral proteolytic activities found in the purified virus. Elastase appears to be the main proteolytic activity which can be detected in the alpha 2-macroglobulin-protease complexes associated with the virus.

Amino Acid Sequence↗

PubMed1990

Complexing of tissue plasminogen activator with PAI-1, alpha 2-macroglobulin, and C1-inhibitor: studies in patients with defibrination and a fibrinolytic state after electroshock or complicated labor.

Release of tissue plasminogen activator (t-PA) and its interaction with plasma protease inhibitors were studied in two patients with massive defibrination, one after electroshock and soft tissue injury and the other after complicated labor; both had very severe hemorrhage. Large quantities of free t-PA were present in the circulation for several hours. Complexes of t-PA with plasminogen activator inhibitor 1 (PAI-1), alpha 2-macroglobulin and C1-inhibitor were also observed. PAI-1 antigen rose dramatically in both patients, and complexes of t-PA with PAI-1 rose rapidly during the period of observation. In contrast, the complexes of t-PA with alpha 2-macroglobulin and C1-inhibitor, present initially, persisted for short periods only and disappeared when free t-PA disappeared from the circulation. Plasmin was generated initially, as indicated by the presence of plasmin-alpha 2-antiplasmin complexes. Plasma concentrations of alpha 2-macroglobulin, C1-inhibitor, antithrombin III, and alpha 2-antiplasmin were severely depleted initially, but rapidly returned to normal. The observations demonstrate that there is a major release of t-PA in such defibrinating patients, that there is a role for protease inhibitors other than PAI-1 in the regulation of endogenous t-PA, and indicate the great rapidity with which such free t-PA is complexed and cleared.

Adult↗

PubMed1990

NMR and ESR studies on human pregnancy zone protein. Comparison with human alpha 2-macroglobulin.

NMR and ESR spectroscopies have been used to examine the plasma protease inhibitor pregnancy zone protein (PZP) and its complex with chymotrypsin. The 1H NMR spectrum of PZP shows relatively few sharp resonances, which, by analogy with human alpha 2-macroglobulin, probably arise from the proteolytically sensitive bait region. Upon reaction with chymotrypsin to form a 1:1 protease.PZP tetramer complex, there is a large increase in the intensity of sharp resonances due to an increase in mobility of these residues. 35Cl NMR has been used to follow binding of zinc and manganese to apo-PZP. Zinc binding causes a linear broadening of the bulk Cl-, consistent with access of Cl- to PZP-bound zinc. Since zinc in the two highest affinity sites in human alpha 2-macroglobulin causes no broadening of Cl-, it is concluded that these zinc sites are absent from PZP. The mobility of chymotrypsin in the PZP.chymotrypsin complex was examined by covalently attaching a nitroxide spin label at the serine residue in the active site of the enzyme and examining the appearance of the ESR spectrum. The chymotrypsin is rigidly held by the PZP to which it is covalently bound. In an analogous experiment performed previously on alpha 2-macroglobulin, chymotrypsin, bound in the presence of methylamine and therefore largely noncovalently bound, was found to be free to rotate inside the cage formed by the protease inhibitor.

Amino Acid Sequence↗

PubMed1990

Alpha-2-macroglobulin is not synthesized by human urothelial cell lines in vitro.

We have analyzed 14 human urothelial cell lines in two different transformation grades for the production of a tumor-associated-alpha-2-macroglobulin. It has been shown in radioimmunoprecipitation and immunoblotting tests that human urothelial cells in vitro do not synthesize the wide-spectrum proteinase inhibitor alpha-2-macroglobulin. Four of the tested cell lines were additionally tested for the expression of specific mRNA which resulted in negative findings. The significance of the absence of alpha-2-macroglobulin in the human urothelial cells is discussed.

Animals↗

PubMedDate not supplied

[Human alpha 2-macroglobulin and its analogs in animals].

Biochemical and immunochemical properties of human alpha 2-macroglobulin and its analogues from cattle, horse, rabbit, guinea pig, rat, mouse, hen and perch have been investigated. It was found that all analogues have the identical molecular mass and structure, being different in their isoelectric point and carbohydrate composition. It was shown that some antigenic properties of macroglobulins remained constant during evolution, whereas other ones were strictly differentiated at the level of families and species. These data allow to classify macroglobulins as proteins which appeared in vertebrates at early stages of evolution revealing only relatively slight changes during the latter.

Animals↗

PubMed1990

Binding of IL-1 beta to alpha-macroglobulins and release by thioredoxin.

Human alpha 2-macroglobulin (H alpha 2M) is a major IL-1 beta binding plasma protein. The characteristics of the H alpha 2M IL-1 beta complex formation suggested, that cleavage of the internal thiol ester in other members of the alpha-macroglobulin family (alpha M) could enable these proteins to bind IL-1 beta. Characterization of optimal conditions for binding 125I IL-1 beta to H alpha 2M showed that H alpha 2M-IL-1 beta complex formation could be obtained over a pH range of 6.3 to 9 in the presence of some metal cations (i.e., Zn2+, Cd2+, Cu2+, Ni2+). Other divalent metal cations (i.e., Mn2+, Mg2+, Ca2+) were without effect. Time kinetic studies showed that binding of IL-1 beta to H alpha 2M was complete within 200 min and that H alpha 2M-IL-1 beta complexes became increasingly resistant to dissociation by boiling in SDS as a function of incubation time. Human pregnancy zone protein, rat alpha 1-, alpha 2-macroglobulin (R alpha 1M, R alpha 2M), all homologous with H alpha 2M, were tested for their ability to bind IL-1 beta. In each instance, alpha M-IL-1 beta complex formation was observed only after treatment of alpha M with methylamine, a primary amine that causes cleavage of the internal thiol ester in alpha M and the appearance of free thiol groups. Similarly, for each of these proteins, complex formation was increased several fold in the presence of Zn2+. Competition experiments using cytokines or proteins of similar molecular mass as IL-1 beta established that only unlabeled IL-1 beta was effective in inhibiting binding of 125I IL-1 beta to H"F" alpha 2M. Acylation of H"F" alpha 2M by diethylpyrocarbonate blocked the binding of IL-1 beta when analyzed by native PAGE. Deacylation of H"F" alpha 2M with hydroxylamine partially restored the binding capacity of H"F" alpha 2M further supporting the involvement of histidyl residues in the Zn2(+)-dependent binding of IL-1 beta. Reduced thioredoxin, but not its alkylated form, from Escherichia coli readily releases H"F" alpha 2M bound IL-1 beta under conditions that did not lead to reduction of disulfide bonds in H"F" alpha 2M. The action of thioredoxin also augmented IL-1-like activity in two independent bioassays suggesting that H"F" alpha 2M bound IL-1 beta is partially biologically inactive or latent. These results suggest that "activated" alpha M exert a modulating role for IL-1 beta by exposing specific binding sites, which are inaccessible in the native proteins.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMedDate not supplied

[Antitrypsin effects of alpha-2-macroglobulin].

Purified preparations of alpha 2-macroglobulin were preincubated with bovine trypsin at various molar ratios. Effects of the preincubation were measured before and after addition of soybean trypsin inhibitor in excess if N-benz-L-arg-p-nitroanilide was used as a substrate. Two types of interaction between alpha 2-macroglobulin and trypsin were detected. One of them was carried out depending on the "trap" hypothesis, another type of the interaction led to the enzyme loss of both proteolytic activity and its ability to hydrolyze the low molecular substrate. The data obtained suggest that various molecular forms of native alpha 2-macroglobulin were responsible for these types of interaction.

Animals↗

PubMed1991

Limited proteolysis of the alpha-macroglobulin rat alpha 1-inhibitor-3. Implications for a domain structure.

Rat alpha 1-inhibitor-3 is a 180-kDa monomeric proteinase inhibitor found in high concentration in rat plasma. By several criteria it has been shown to be a member of the family of alpha-macroglobulin proteinase inhibitors often exemplified by the tetrameric human alpha 2-macroglobulin. We have used limited proteolysis of rat alpha 1-inhibitor-3 to probe the domain structure of this family of proteins. Proteinases of different specificities, including trypsin, chymotrypsin, thermolysin, and Staphylococcus aureus V8 proteinase, were employed and a common fragmentation pattern was observed when the reaction products were examined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. These fragments were electrotransferred to polyvinylidene difluoride membranes and subjected to NH2-terminal amino acid sequence analysis in order to position them within the context of the primary structure. The fragmentation pattern may define the domain structure of alpha 1-inhibitor-3 and serve as a model for the domain organization of the family of alpha-macroglobulin proteinase inhibitors.

Acute-Phase Proteins↗

PubMed1991

Maternal serum alpha 2-macroglobulin and fetal growth retardation.

Maternal serum alpha 2-macroglobulin levels were measured twice, at approximately 18 and 30 weeks' gestation, in 289 pregnant women who later delivered at or after 37 weeks. Levels were elevated as early as 18 weeks' gestation in women destined to have a growth-retarded infant, and this elevation persisted through 30 weeks' gestational age. Furthermore, levels were higher in white women than black, in smokers than in non-smokers, and in thin than in heavier women. When the effect of alpha 2-macroglobulin on birth weight was evaluated in a multiple regression analysis adjusting for gestational age, race, body size, smoking, fetal sex, and a history of a low birth weight infant, high alpha 2-macroglobulin levels were associated with a statistically significant decrease in birth weight. The effect was greater in women who smoked. This relationship did not appear to be associated with differences in serum zinc or hematocrit levels.

Adult↗

PubMed1985

Characterization of human pregnancy zone protein. Comparison with human alpha 2-macroglobulin.

Native human pregnancy zone protein (PZP), a close homolog of alpha 2-macroglobulin (alpha 2M), can be obtained in approximately 20% yield from pooled late pregnancy plasma or serum by a combination of polyethylene glycol precipitation, euglobulin precipitation, DEAE-Sephacel chromatography, zinc-chelate affinity chromatography, and negative affinity chromatography on insolubilized antibodies against human serum proteins. Both proteins are similarly organized as disulfide-bridged dimers of 360 kDa containing 180-kDa subunits. These dimers constitute the proteinase-binding units of PZP, and in contrast to alpha 2M, they appear to be only loosely associated, indicating a subtle difference in the quaternary structure of these alpha-macroglobulins. The preparations contain functionally intact beta-cysteinyl-gamma-glutamyl thiol esters, located in the same nonapeptide sequence as found in alpha 2M, and form complexes with a variety of proteinases in which a large fraction of the proteinase is bound covalently. Proteinases bound to PZP are still active and poorly accessible to reaction with large inhibitors like alpha 1-proteinase inhibitor. The structural and functional features of PZP indicate that PZP and alpha 2M, although extremely similar, may have different yet overlapping sets of proteinases as targets. It is possible that PZP mainly controls the activity of cellular proteinases released under conditions of increased cellular turnover and that PZP could be the human equivalent to the acute phase alpha-macroglobulins known in other species.

Chemical Precipitation↗

PubMed1986

Effects of alpha-macroglobulins and murinoglobulins on the hemagglutination by influenza C virus.

Rat alpha-1- and alpha-2-macroglobulins as well as rat murinoglobulins I and II were shown to inhibit hemagglutination by influenza C virus. In marked contrast, neither alpha-macroglobulins nor murinoglobulins from mouse or guinea pig plasma had the inhibitory activity. These results suggest that the hemagglutination-inhibiting activity of rat alpha-macroglobulins or murinoglobulins is not related to their protease-binding capacity.

Animals↗

PubMed1987

A functional, thioester-containing alpha 2-macroglobulin homologue isolated from the hemolymph of the American lobster (Homarus americanus).

An alpha 2-macroglobulin-like protease inhibitor was isolated from the cell-free hemolymph of the american lobster (Homarus americanus) by ion-exchange chromatography and gel filtration. Whereas the undissociated molecule has a molecular weight of 342,000 as determined by ultracentrifugation studies, under reducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the protein has a subunit molecular weight of 180,000. On the basis of this and other evidence, we conclude that the lobster protein is a dimer consisting of two disulfide-bonded monomers. The purified protein inhibits proteolytic enzymes but protects the esterolytic activity of trypsin toward low molecular weight substrates from inactivation by soybean trypsin inhibitor. The methylamine sensitivity of this activity suggests the presence of an internal thioester bond. This was confirmed by the covalent incorporation of [14C]methylamine, by the formation of Mr 55,000 and 125,000 autolytic cleavage fragments in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and, more directly, by the amino acid sequence of a tryptic peptide containing the putative thioester region. Whereas the N-terminal amino acid sequence (22 residues) of the protein revealed an overall identity of only 18% when compared with the human protein, the sequence of the thioester-containing peptide was highly conserved, both with respect to human alpha 2-macroglobulin and to other proteins having a thioester bond. The protein showed the "slow to fast" conformational change typical in alpha 2-macroglobulins in nondenaturing gel electrophoresis after treatment with trypsin, but not after incubation with methylamine.

Amino Acid Sequence↗

PubMed1988

[Comparative studies of bronchial secretions in children with chronic, nontuberculous lung diseases. 3. The detection of lysozyme, transferrin, alpha 1-antitrypsin, alpha 2-macroglobulin, haptoglobin and alpha 1-acid glycoprotein].

In 166 bronchial secretions from 63 children with chronic nontuberculous lung diseases lysozyme, transferrin, alpha 1-antitrypsin, alpha 2-macroglobulin, haptoglobin and alpha 1-acid glycoprotein were estimated. In patients with hard bronchoscopic or bronchographic alterations a reduction of lysozyme, alpha 1-antitrypsin and alpha 2-macroglobulin could be found. These proteins were measured more frequently in cases with dark altered mucosa. Moreover no relation could be found between transferrin, alpha 1-antitrypsin and alpha 2-macroglobulin and the outbreak of the diseases. -In bacterial contaminated secretions transferrin could be demonstrated more frequently in comparison with sterile bronchial secretions.

Adolescent↗