Herpes zoster and facial palsy.
A case of facial palsy associated with herpes zoster is presented. A good response was obtained using treatment with acyclovir and prednisone.
Acyclovir↗
Biomedical subjects
S R Feldman
Publications and source records attributed to S R Feldman.
Organic affective disorder in a patient with congenital adrenal hyperplasia.
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Adrenal Hyperplasia, Congenital↗
Carbohydrate recognition systems in amphibians: primitive alpha 2-macroglobulin receptors.
Two alpha-macroglobulins were isolated from the plasma of the frog. Murine clearance studies were performed with these proteins after they were reacted with proteinase. These studies indicated that clearance behavior was more complex than observed with avian or human homologues, since it involved not only specific receptors for the complex, but also carbohydrate recognition. Recognition of one of these macroglobulins by both the alpha-macroglobulin receptor and carbohydrate receptors required conformational change in the inhibitor. Clearance studies were then performed in frogs to probe the nature of carbohydrate receptor recognition. Model glycoproteins were employed to avoid the problem of heterogeneous carbohydrate end groups in the alpha-macroglobulins. These studies demonstrated that the N-acetylglucosamine/mannose receptor is the major carbohydrate recognition system in frogs.
Animals↗
Further characterization of the platinum-reactive component of the alpha 2-macroglobulin-receptor recognition site.
alpha 2-Macroglobulin (alpha 2M)-methylamine that had been allowed to react with cis-dichlorodiammineplatinum(II) (cis-DDP) bound with greatly reduced affinity to specific alpha 2M receptors, as determined by macrophage binding studies in vitro and plasma-clearance experiments in vivo. Subsequent reaction with diethyl dithiocarbamate completely restored receptor recognition function. The optimal effect was obtained when the diethyl dithiocarbamate concentration was twice the total platinum concentration. alpha 2M-methylamine that was allowed to react with H2O2 competed less effectively for specific cell-surface binding sites, as demonstrated by studies both in vivo and in vitro. The apparent dissociation constant was increased nearly 7-fold by a 15 min exposure to H2O2. alpha 2M-methylamine was affected significantly less by the H2O2 exposure after pretreatment with cis-DDP. Amino acid analysis indicated that H2O2 treatment of alpha 2M modified 19 of the 25 methionine residues per alpha 2M subunit. Pretreatment with cis-DDP protected two to four of these methionine residues. The only other residue altered by H2O2 treatment of alpha 2M was histidine. A net decrease of two histidine residues per subunit was observed, but cis-DDP pretreatment did not alter this result. In order to rule out the slight possibility that histidine modification might account for the observed H2O2-induced loss in receptor recognition, diethyl pyrocarbonate was employed as a histidine-modifying reagent. This treatment modified 53 histidine residues in both native and fast-form alpha 2M. Fast-form alpha 2M was still recognized by the alpha 2M receptor, as determined by studies both in vivo and in vitro; however, a fraction of the modified protein now cleared via the acyl-low-density-lipoprotein receptor as well. Reaction of diethyl pyrocarbonate-treated alpha 2M with hydroxylamine reversed derivatization of 43 of the 53 histidine residues. Moreover, this treatment also resulted in an alpha 2M fast-form preparation that was recognized only by the alpha 2M receptor. It is concluded that cis-DDP and H2O2 modify a critical methionine residue in the primary sequence of the alpha 2M-receptor recognition site.
Amino Acids↗
Purification and characterization of a "half-molecule" alpha 2-macroglobulin from the southern grass frog: absence of binding to the mammalian alpha 2-macroglobulin receptor.
An alpha-macroglobulin (alpha 2M), which is a dimer consisting of two non-disulfide-bonded subunits, was identified and purified from frog plasma by Ni2+ chelate affinity chromatography. This frog "half-molecule" alpha-macroglobulin migrated as an alpha 2-globulin in cellulose-acetate electrophoresis rather than as the previously described frog alpha 1M, which exists as a tetramer formed by the noncovalent association of disulfide-bonded pairs. A molecular weight of approximately 380 000 was obtained by gel-filtration high-pressure liquid chromatography, and in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) the protein migrated as a single band of Mr approximately 180 000 before and after reduction. No evidence was obtained for association of this protein to a higher molecular weight species. After the preparation was heated, additional bands were obtained in SDS-PAGE with Mr approximately 60 000 and 12 000. The additional bands were not obtained after heating methylamine-treated preparations. The circular dichroic spectrum of frog alpha 2M exhibits negative ellipticity over the region 205-250 nm with a minimum at 216 nm. After reaction with proteinase, a decrease in the absolute mean residue rotation was obtained. Amino acid analysis demonstrated that frog alpha 2M and alpha 1M are similar in composition to avian and mammalian alpha-macroglobulins; however, there are sufficient differences in the composition of these two amphibian alpha-macroglobulins to support the conclusion that they are distinct proteins. Frog alpha 2M bound approximately 0.5 mol of trypsin/mol of inhibitor. This binding was abolished by pretreatment with methylamine.(ABSTRACT TRUNCATED AT 250 WORDS)
Amino Acids↗
Forehead ulcer in a homosexual man. Cryptococcosis.
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Adult↗
A three-dimensional model of a unique proteinase inhibitor: alpha 2-macroglobulin.
alpha 2-Macroglobulin inhibits many proteinases by a unique mechanism termed "trapping" depicted in Figure 3A,B. This article details a mechanism by which a large proteinase, such as plasmin, binds in a molar ratio between 1 and 2 to 1 proteinase to inhibitor. The article also discusses the placement of the bait region in relation to the thiol-esters within this model. Future investigation is required to confirm the hypothesized mechanism of plasmin binding as well as the hypothesized location of the bait region.
Binding Sites↗
Specificity of alpha 2-macroglobulin covalent cross-linking for the active domain of proteinases.
The reaction of alpha 2-macroglobulin (alpha 2M) with the two-chain enzyme plasma kallikrein results in covalent bond formation between the catalytic subunit and the inhibitor. We have recently published a model of alpha 2M which suggests that this phenomenon may be a general mechanism when multisubunit proteinases are inactivated by alpha 2M. In order to test this hypothesis, we studied the reactions of factor Xa, plasmin, streptokinase-plasmin and alpha-thrombin with alpha 2M. In the case of factor Xa the catalytic heavy chain demonstrated greater than 99% covalent incorporation while over 97% of the light chain failed to crosslink to the inhibitor. Preferential binding of the catalytic light chains of plasmin (70% covalent incorporation) and plasmin in complex with streptokinase (79% covalent incorporation) was also observed. Finally, 82% covalent incorporation of the catalytic heavy chain of alpha-thrombin was found. These studies demonstrate that in the case of multisubunit proteinases, the chain containing the active site demonstrates preferential binding as predicted by the model supporting placement of the site of covalent binding close to the "bait region" of alpha 2M.
Binding Sites↗
Purification and characterization of frog alpha-macroglobulin: receptor recognition of an amphibian glycoprotein.
Frog alpha-macroglobulin was purified to apparent homogeneity by Ni2+ chelate affinity chromatography. Frog alpha-macroglobulin migrated as an alpha 1-globulin in cellulose acetate electrophoresis. A molecular weight of 730 000 was obtained by equilibrium sedimentation, and in sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE), the protein migrated as a single band of Mr approximately 360 000 before reduction and Mr approximately 180 000 after reduction. Treatment with trypsin resulted in subunit cleavage to yield a fragment of Mr approximately 90 000. After being heated, the protein fragmented, migrating in SDS-PAGE as two bands of Mr approximately 120 000 and 60 000. This fragmentation was inhibited by prior reaction of the protein with methylamine. In native pore-limit electrophoresis the protein exhibited the characteristic "slow" to "fast" conformational change of protease-treated alpha-macroglobulins. In contrast, typical "slow" to "fast" conformational change was not observed in native PAGE with this preparation. Moreover, the protein incorporated approximately 2 mol of [14C]methylamine/mol of inhibitor without demonstrating a change in mobility in native PAGE. In circular dichroism studies, the protein exhibited a spectrum similar to that of human alpha 2M. Reaction with trypsin resulted in a broadening and decrease in the magnitude of the spectrum. Reaction with methylamine resulted in similar changes, but of smaller magnitude. The inhibitor bound approximately 0.7 mol of trypsin in both radiolabeled protease binding and amidolytic titration studies. 125I-Labeled native frog alpha 1M was removed slowly from the circulation of mice with a t1/2 greater than 2h.(ABSTRACT TRUNCATED AT 250 WORDS)
Amino Acids↗
Binding of alpha 2-macroglobulin to hepatocytes: mechanism of in vivo clearance.
The binding of 125I-labeled human alpha 2-macroglobulin-methylamine to adult rat hepatocytes in primary culture was studied at 4 degrees C. Cells which had been in culture for 4 hours exhibited steady state ligand binding after 1 hour, a receptor number of 22,400 receptors per cell, and a dissociation constant of 0.6 nM. Adult rat hepatocytes exhibited a significant decrease in receptor number with increased time in primary culture with less than 10% of the initial number of receptors remaining after 2 days (p less than 0.01). In autopsy studies of mice injected intravenously with 125I-labeled alpha 2-macroglobulin-methylamine, greater than 90% of the cleared ligand was found in the liver. Autoradiography of the liver demonstrated that 80% of the ligand was cleared by hepatocytes. It is concluded that the hepatocytes are the primary pathway for clearance from the circulation of receptor recognized alpha 2-macroglobulin.
Animals↗
Model of alpha 2-macroglobulin structure and function.
A model of alpha 2-macroglobulin is presented that is compatible with previous structural, functional, and phylogenetic studies of the protein. The model of the molecule resembles a hollow cylinder and is comprised of two identical functional halves with three C2 axes of symmetry and no mirror planes. The "trap mechanism" of this proteinase inhibitor is effected by slight movement of two trap arms per "half-molecule." Evidence for this model is obtained from the study of the structure and proteinase binding of the molecule. By using this model, predictions are made concerning proteinase binding ratios, receptor recognition, and "slow-to-fast" conformational change of the molecule.
Animals↗
Fluorescent probes as a measure of conformational alterations induced by nucleophilic modification and proteolysis of bovine alpha 2-macroglobulin.
Conformational alterations occurring in bovine alpha 2-macroglobulin (alpha 2M) resulting from proteolysis and nucleophilic modification have been monitored by UV difference spectra, circular dichroism, and changes in the fluorescence of 6-(p-toluidino)-2-naphthalenesulfonate (TNS) and bis(8-anilino-1-naphthalenesulfonate) (Bis-ANS). The results of this study indicate that these two dyes appear capable of differentiating between conformational changes induced by proteolysis and those induced by methylamine treatment. It appears that TNS is a sensitive probe for monitoring protease-induced but not methylamine-induced conformational changes in bovine alpha 2M. Bis-ANS, on the other hand, appears suitable for monitoring conformational changes induced by methylamine treatment or proteolysis of the molecule and was used as a probe to monitor the kinetics of the conformational change induced by methylamine treatment. It was found that the conformational change did not occur simultaneously with cleavage of the thiol ester bonds by the nucleophile, measured by titration of free sulfhydryl groups with 5,5'-dithiobis(2-nitrobenzoate). The data are consistent with a model in which initial nucleophilic attack results in exposure of sulfhydryl groups, resulting in a conformational change measured by an increase in fluorescence. This event is followed by a unimolecular step representing a conformational change in the protein that results in a further increase in the fluorescence signal. The second-order rate constant for hydrolysis of the thiol ester bonds was determined to be 3.4 +/- 1.0 M-1 s-1, while the rate constant for the conformational change was (4.4 +/- 0.8) X 10(-4) s-1.
Anilino Naphthalenesulfonates↗
Comparison of the binding of chicken alpha-macroglobulin and ovomacroglobulin to the mammalian alpha 2-macroglobulin receptor.
Chicken alpha-macroglobulin (alpha M) and ovomacroglobulin were purified by Ni+2 chelate chromatography. These proteins had similar subunit structure as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Chicken alpha M bound 1.0 mol and ovomacroglobulin bound 0.8 mol 125I-trypsin per mol inhibitor, respectively. Ovomacroglobulin cleared rapidly from the circulation of mice, and the clearance was inhibited by asialoorosomucoid, but native chicken alpha M cleared slowly (t 1/2 greater than 1 h). After reaction with trypsin, this alpha-macroglobulin cleared rapidly (t 1/2 = 3 min), and this clearance was inhibited by a 1000-fold molar excess of human alpha 2M-methylamine. Ovomacroglobulin-trypsin did not inhibit the binding of 0.2 nM 125I-labeled human alpha 2M-methylamine to mouse peritoneal macrophages in vitro, but chicken alpha M reacted with trypsin inhibited the binding by 50% at 1.9 nM. A kappa I of 1.1 nM was calculated for the binding of chicken alpha M-trypsin to the mammalian alpha-macroglobulin receptor. This affinity is comparable to that obtained with human and bovine alpha 2M.
Amino Acids↗
Circular dichroic spectroscopy of non-human alpha-macroglobulins.
Bovine, chicken and frog alpha-macroglobulins and ovomacroglobulin were studied by circular dichroic spectroscopy over the region 205-250 nm. All four spectra exhibited negative ellipticity with minima at about 215 nm similar to that reported for human alpha 2-macroglobulin. On reaction of the alpha-macroglobulins with trypsin, the spectrum of each of the four changed similarly. However, these proteins exhibited different conformational changes when treated with methylamine. These differences were exploited to determine which characteristics of alpha-macroglobulins correlate with changes in circular dichroic spectroscopy.
Animals↗
Identification of "embryonin" as bovine alpha 2-macroglobulin.
Pedersen fetuin contains a contaminant, previously named "embryonin" that exhibits immuno-cross reactivity with human alpha2-macroglobulin (alpha2Mh). In the present study, it is demonstrated that this protein coelutes with alpha2Mh in gel filtration chromatography and can be purified to homogeneity by Zn2+ chelate chromatography. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), this contaminant exhibited similar subunit size, protease-induced cleavage fragments, and heat fragmentation as alpha2Mh. 125I-trypsin and 125I-chymotrypsin each bound at a ratio of 0.9 mol/mol to this fetuin-derived native alpha2M (alpha2Mf) and at a ratio of less than 0.2 mol/mol to methylamine-treated alpha2Mf. As determined by SDS-PAGE, 1:1 molar ratio of protease to alpha2Mf cleaved each alpha2Mf subunit to fragments of Mr approximately 72,000. At a 0.2:1 molar ratio of trypsin to alpha2Mf-methylamine, every alpha2Mf-methylamine subunit was cleaved to polypeptide chains of Mr approximately 72,000 and 110,000. In native PAGE, alpha2Mf and alpha2Mf-methylamine migrated with the same mobility; after reaction with trypsin their mobilities increased similarly. 125I-alpha2Mf cleared from the circulation of mice with a t1/2 of 30 min. The trypsin or methylamine derivative of 125I-alpha2Mf cleared with t1/2 of less than 5 min and clearance was competable when the ligand was co-injected with a large molar excess of unlabeled alpha2Mh-methylamine. alpha2Mf, 0.3 nM, treated with trypsin or methylamine, inhibited 50% of the binding of 0.1 nM 125I-alpha2Mh-methylamine to specific receptors on mouse peritoneal macrophages in vitro. Native alpha2Mf did not inhibit significantly the binding of the ligand at this concentration. Bovine alpha2M (alpha2Mb) was purified from plasma by Ni2+ chelate chromatography. By SDS-PAGE, amino acid analysis, and cyanogen bromide peptide mapping, it was indistinguishable from the alpha2M purified from fetuin. It is concluded that embryonin is bovine alpha2M.
Amino Acids↗
Conformation-specific precipitation of human alpha 2-macroglobulin by divalent zinc or calf thymus histone H3.
Highly purified native alpha 2-macroglobulin (alpha 2M), alpha 2M-trypsin, and alpha 2M-methylamine were compared in experiments designed to study protein precipitation. Significant turbidity developed within 30 min in solutions containing histone H3 and either alpha 2M-methylamine or alpha 2M-trypsin, as determined by absorbance at lambda = 550 nm. No turbidity was detected in solutions that contained histone H3 and native alpha 2M or histone H3 alone. Experiments with radioiodinated histone H3 or radioiodinated proteinase inhibitor confirmed that both the H3 and the alpha 2M "fast" forms (alpha 2M-methylamine, alpha 2M-trypsin) were present in the precipitates generated. As much as 70% of the 125I-alpha 2M-methylamine was recovered in the precipitate after incubation with a 120-fold molar excess of H3 (concentration of alpha 2M-methylamine, 0.28 microM). The ratio of histone to proteinase inhibitor by weight in the precipitate was approximately two. Under comparable conditions, somewhat less alpha 2M-trypsin precipitated from solutions containing H3 than did alpha 2M-methylamine; however, inactivation of the alpha 2M-trypsin with phenylmethylsulfonyl fluoride prior to incubation increased the level of precipitation significantly. Solutions containing poly-L-lysine (Mr approximately 13,000) instead of histone did not form precipitates with any of the forms of alpha 2M studied. In a second set of experiments, radioiodinated native alpha 2M, alpha 2M-trypsin, and alpha 2M-methylamine were incubated in solutions containing ZnCl2, BaCl2, CdCl2, CuSO4, MgCl2, or NiCl2 (concentration of divalent cation between 5 microM and 1.0 mM). Native alpha 2M was soluble in all of these salts. By contrast, alpha 2M-methylamine and alpha 2M-trypsin precipitated extensively from solutions containing greater than 100 microM ZnCl2. Precipitation was greater than 90% complete at 1 mM ZnCl2. A similar effect was not observed with any of the other divalent cations.
Cations, Divalent↗
Alpha 2-macroglobulin 'fast' forms inhibit superoxide production by activated macrophages.
Mouse peritoneal macrophages activated by bacillus Calmette-Guerin (BCG) were incubated with human alpha 2-macroglobulin converted to its 'fast' form with either trypsin or methylamine before being stimulated with phorbol myrystate acetate. Both alpha 2-macroglobulin-trypsin and alpha 2-macroglobulin-methylamine inhibited macrophage production of superoxide anion (O2-) while native alpha 2-macroglobulin had little effect except at high concentration. The alpha 2-macroglobulin 'fast' forms, which bind with a Kd of about 8 nM, inhibited 50% generation of O2- (ID50) at a concentration of 7 nM while alpha 2-macroglobulin inhibited O2- production with an ID50 of 141 nM. The 'fast' forms of alpha 2-macroglobulin may play a role in the feedback regulation of inflammatory reactions.
Animals↗
In vitro binding and in vivo clearance of human alpha 2-macroglobulin after reaction with endoproteases from four different classes.
The binding of human alpha 2-macroglobulin complexed with trypsin, papain, thermolysin and cathepsin-D to murine macrophages was studied at 4 degrees C. Similar dissociation constants (0.4 nM) were determined for all of the complexes except alpha 2-macroglobulin-cathepsin-D (0.7 nM). Radioiodinated alpha 2-macroglobulin-protease complexes were injected into mice, and the clearance studied. Native alpha 2-macroglobulin cleared slowly, as previously reported, while greater than 50% of the complexes formed with trypsin, papain and thermolysin cleared in less than 5 min. The clearance of alpha 2-macroglobulin-cathepsin-D was biphasic, suggesting that only about half the alpha 2-macroglobulin was present in a reacted complex.
Animals↗