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PubMed1977

Modification of tyrosine residues of the lactose repressor protein.

Reaction of the lactose repressor protein from Escherichia coli with high molar excesses (up to 800 fold) of tetranitromethane resulted in modification of tyrosine residues in the amino-terminal and core regions of the molecule. Tyrosines 7 and 17 exhibit significant reactivity at low levels (5-10 fold molar excess) of tetranitromethane. The loss of operator binding activity upon nitration at these low concentrations of reagent indicates involvement of these two tyrosines in the binding process. Inducer binding activity was maintained at approx. 90% of unreacted repressor for all excesses of reagent studied. Addition of inducer to the repressor prior to reaction resulted in decreased modification of tyrosines in the core region, but anti-inducers did not affect the reaction significantly. The effect of inducers on the pattern of reaction apparently reflects the conformational change which occurs upon binding of these ligands. Acetylation of the repressor protein with N-acetylimidazole modified lysines and tyrosines with complete loss of operator binding activity and retention of 75-80% of inducer binding activity.

Bacterial Proteins↗

PubMed1980

Reconstitution of turkey erythrocyte beta-adrenergic receptors into human erythrocyte acceptor membranes. Demonstration of guanine nucleotide regulation of agonist affinity.

Digitonin-solubilized turkey erythrocyte beta-adrenergic receptors were reconstituted by dialysis into human erythrocyte acceptor membranes which lack beta receptors. Incorporation of turkey beta receptors into acceptor membranes was directly proportional to the quantity of soluble protein added to the reconstitution system. Reconstituted beta receptors demonstrate saturable [125I]iodohydroxybenzylpindolol binding (Bmax = 11.1 +/- 0.8 fmol/mg, K = 77.8 +/- 8.6 pM) and stereospecificity ((-)-propranolol, K = 11.0 nM; (+)-propranolol, K = 2000 nM; (-)-isoproterenol, K = 250 nM; (+)-isoproterenol, K = 82 micro M). Reconstituted beta receptors appear to be incorporated into acceptor membranes as integral proteins. Reconstituted beta receptors cannot be extracted by high salt or pH (3 to 11); detergent is required for resolubilization of reconstituted beta receptors. Adenylate cyclase stimulation was not obtained in reconstituted membranes since acceptor membranes lack a catalytic subunit. However, guanine nucleotide regulation of agonist affinity was observed indicating a functional reconstitution. GTP (100 micro M) produces a 5-fold decrease in the affinity of isoproterenol for reconstituted beta receptors. Experiments with sulfhydryl reagents indicate that the reconstituted beta receptor couples with the guanine nucleotide regulatory protein of the acceptor membranes. These data describe the successful reconstitution of a beta receptor and indicate that the reconstituted beta receptor can interact with the GTP binding protein of human erythrocyte acceptor membranes.

Animals↗

PubMed1985

Identification and characterization of a hapten-modifiable TEPC 15 cross-reactive idiotype in swine.

Rabbits and swine immunized with TEPC 15 IgA, goats immunized with T15-positive IgM and swine immunized with affinity-pure swine anti-phosphorylcholine (PC) all produce antibodies which recognize a hapten-inhibitable idiotypic determinant on swine anti-PC. The similarity in reactivity and order of inhibitability with various PC analogs of the heterologous (swine anti-TEPC 15) and isologous (swine anti-swine anti-PC) reagents indicates that they recognize a related idiotype and suggest it may be the predominant idiotype expressed on swine anti-PC antibodies. The heterologous and isologous anti-idiotypic reagents generated in this study recognize swine and mouse anti-PC but not normal swine IgM, IgG or MOPC 460. Only reactions with swine anti-PC and mouse T15-positive anti-PC proteins are hapten-inhibitable. The greater inhibitory capacity of trimethylammonium and acetylcholine than PC suggests that the idiotope(s) recognized on swine anti-PC by the anti-idiotypic reagents is integral rather than peripheral to the anti-PC binding site. The nearly exclusive IgM anti-PC response of swine to Streptococcus pneumoniae R36A and PC-Brucella have so far hindered attempts to study the isotypic distribution of the idiotype.

Animals↗

PubMed1979

Some molecular properties of NAD(P)H dehydrogenase from rat liver.

NAD(P)H dehydrogenase (EC 1.6.99.2) purified from rat liver cytosol revealed three discrete bands, of mol.wts. about 27000, 18000 and 9000, when subjected to polyacrylamidegel electrophoresis in the presence of sodium dodecyl sulphate. Elution of the bands from the gel and individual re-electrophoresis on separate gels showed that the 27000-mol.wt. band yielded three bands similar to those obtained with the intact enzyme, whereas the 18000-mol.wt. band retained its characteristic mobility. Amino acid analysis of native enzyme and protein extracted from each of the three bands from sodium dodecyl sulphate/polyacrylamide gels suggests that the native enzyme is composed of two subunits and that each subunit consists of two dissimilar non-covalently bound polypeptides, so that altogether the enzyme is composed of four polypeptides, two of mol.wt. 18000 and two of mol.wt. 9000. NAD(P)H dehydrogenase was active over a wide pH range with no sharp optimum. The same K(m) value for NADH but different values for V(max.) were obtained for the enzyme purified from Sprague-Dawley and Wistar rats. In immunodiffusion, however, the enzymes from the two rat strains showed a reaction of complete identity. NAD(P)H dehydrogenase was effectively inhibited by thiol-blocking reagents, indicating that the activity is dependent on free thiol group(s). By amino acid analysis six cysteine residues were found per mol of enzyme. Guanidino-group- and amino-group-selective reagents had only moderate inactivating effects on the enzyme activity.

Amino Acids↗

PubMed2004

Outer pore architecture of a Ca2+-selective TRP channel.

The TRP superfamily forms a functionally important class of cation channels related to the product of the Drosophila trp gene. TRP channels display an unusual diversity in activation mechanisms and permeation properties, but the basis of this diversity is unknown, as the structure of these channels has not been studied in detail. To obtain insight in the pore architecture of TRPV6, a Ca(2+)-selective member of the TRPV subfamily, we probed the dimensions of its pore and determined pore-lining segments using cysteine-scanning mutagenesis. Based on the permeability of the channel to organic cations, we estimated a pore diameter of 5.4 A. Mutating Asp(541), a residue involved in high affinity Ca(2+) binding, altered the apparent pore diameter, indicating that this residue lines the narrowest part of the pore. Cysteines introduced in a region preceding Asp(541) displayed a cyclic pattern of reactivity to Ag(+) and cationic methylthio-sulfanate reagents, indicative of a pore helix. The anionic methanethiosulfonate ethylsulfonate showed only limited reactivity in this region, consistent with the presence of a cation-selective filter at the outer part of the pore helix. Based on these data and on homology with the bacterial KcsA channel, we present the first structural model of a TRP channel pore. We conclude that main structural features of the outer pore, namely a selectivity filter preceded by a pore helix, are conserved between K(+) channels and TRPV6. However, the selectivity filter of TRPV6 is wider than that of K(+) channels and lined by amino acid side chains rather than main chain carbonyls.

Amino Acid Sequence↗

PubMed1993

Location of conserved residue histidine-38 of the epsilon subunit of Escherichia coli ATP synthase.

The function and location of residue His-38 of the epsilon subunit of the Escherichia coli F1-ATPase were investigated. His-38 was replaced by glutamine and cysteine through site-directed mutagenesis to produce epsilon H38Q and epsilon H38C, respectively. Both epsilon H38Q and epsilon H38C fulfilled epsilon function in vivo as determined by growth on nonfermentable carbon sources, growth yield on limiting glucose, and recovery of cells from energy starvation conditions. epsilon H38Q and epsilon H38C were purified and studied in vitro. Pure epsilon H38C reacted rapidly with Ellman's reagent, indicating a surface location of the introduced cysteine. epsilon H38C which had been reconstituted with epsilon-depleted F1-ATPase could be linked specifically to the gamma subunit using two different heterobifunctional sulfhydril-reactive/photoreactive crosslinking agents, indicating that residue 38 lies near gamma. The mutated epsilon subunits were unaltered in their ability to inhibit epsilon-depleted F1-ATPase in vitro, even after modification of epsilon H38C with the bulky reagents fluorescein maleimide and N-(1-anilinonaphthyl-4)maleimide. It seems unlikely, therefore, that residue His-38 of epsilon interacts directly with gamma. Both the epsilon H38Q and epsilon H38C mutations reduced the recognition of epsilon by monoclonal antibody epsilon-1, but recognition of epsilon H38C was not further reduced by reaction with fluorescein maleimide. These results imply that residue 38 is not directly part of the epsilon-1 epitope, but plays a role in its formation.

Antibodies, Monoclonal↗

PubMed1992

Purification and characterization of a thermostable carboxypeptidase (carboxypeptidase Taq) from Thermus aquaticus YT-1.

A thermostable carboxypeptidase, which we named carboxypeptidase Taq, was purified from Thermus aquaticus YT-1 and characterized. The molecular weight of the enzyme was estimated to be about 56,000 and 58,000 on SDS-polyacrylamide gel electrophoresis and gel filtration, respectively, indicating that the enzyme has a monomeric structure. The optimum pH of the enzyme was 8.0, and the optimum temperature for the reaction was 80 degrees C. The enzyme activity was dependent on cobalt ion and was inhibited by metal-chelating reagents, indicating that the enzyme is a metalloenzyme. The enzyme had high thermostability independent of cobalt ion; about 90% of its activity remained even after treatment at 80 degrees C for 5 h. The enzyme showed broad substrate specificity, although proline at the C-terminus of peptides was not cleaved. The enzyme released amino acids sequentially from the C-terminus.

Amino Acid Sequence↗

PubMed1991

Molecular properties of lysine-2,3-aminomutase.

Lysine-2,3-aminomutase purified from Clostridium subterminale SB4 is reported to exhibit an apparent subunit Mr of 48,000, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and the undenatured enzyme exhibits an apparent Mr of 285,000, as determined by electrophoretic mobility and gel permeation chromatography (Chirpich, T. P., Zappia, V., Costilow, R. N., and Barker, H. A. (1970) J. Biol. Chem. 245, 1778-1789). The diffusion coefficient of the enzyme is 3.36 x 10(-7) cm2/s, as determined by quasielastic light scattering. The overall Mr calculated from the diffusion coefficient and the published sedimentation coefficient is 259,000. Cross-linking experiments using glutaraldehyde and dithiobis(succinimidylpropionate) as cross-linking reagents indicate that the enzyme has a hexameric quaternary structure. The number of major cyanogen bromide peptides, compared with the methionine content of the enzyme, is consistent with the subunits being identical, and isoelectric focusing also is consistent with identical subunits. The circular dichroism of the enzyme indicates that it is a highly ordered structure, which is estimated to consist of 26% alpha-helix and 48% beta-sheet. The enzyme contains approximately six molecules of pyridoxal 5'-phosphate per hexamer, as determined by the phenyl-hydrazine method. The amino acid analysis of the enzyme, after performic acid oxidation, indicates that it contains approximately 13 cysteine residues per subunit. Six sulfhydryl groups per hexamer react readily with 5,5'-dithiobis-2-nitrobenzoate, indicating that one sulfhydryl group is accessible per subunit.

Amino Acid Isomerases↗

PubMed1980

High-molecular-weight antigenic protein complex in the outer membrane of Neisseria gonorrhoeae.

The outer membrane of Neisseria gonorrhoeae contains approximately 15 proteins, with 2 or 3 accounting for over 75% of the total protein mass. Samples of outer membrane from strain 2686 T4 analyzed by electrophoresis in 2% polyacrylamide gels revealed a band with an apparent molecular weight of 800,000. The band was protein material, as indicated by trypsin and pronase sensitivity and by L-[3H]proline incorporation. Peptidoglycan, nucleic acids, and carbohydrate were not detected in the band. Dye binding, L-[3H]proline incorporation, and labeling of solubilized outer-membrane proteins with 125I-labeled Bolton-Hunter reagent indicated that the band made up 10 to 13% of the total protein mass of isolated outer membranes. The material in the band was purified by gel filtration and, after reduction and alkylation, quantitatively recovered as subunits with an apparent molecular weight of 76,000. The protein in complex form was exposed at the cell surface, as evidenced by labeling whole cells with 125I by using a lactoperoxidase-catalyzed reaction and with CNBr-activated dextran. Rabbit serum raised against whole 2686 T4 gonococci contained antibody which reacted with the protein complex. The protein complex was detected in all gonococcal strains tested, but its presence could not be demonstrated in several other gram-negative species.

Antigens, Bacterial↗

PubMed1994

Membrane properties of antiviral phospholipids containing heteroatoms in the acyl chains.

Phospholipids containing heteroatoms in the lipid acyl chains, e.g., 1,2-bis(12-methoxydodecanoyl)-sn-3-phosphocholine (L-AC2), exhibit potent anti-HIV activity [Pidgeon, C., Markovich, R. J., Liu, M. D., Holzer, T., Novak, R., & Keyer, K. (1993) J. Biol. Chem. 268, 7773-7778]. AC2 is a synthetic chemical analog of the long-chain phospholipid, dimyristoylphosphatidylcholine (DMPC). Sonicated AC2 lipid dispersions would not entrap either Dextran-4000 or Mn2+ used as aqueous space markers. The lack of entrapment of aqueous space markers indicates that the AC2 structures do not contain an aqueous core that is the characteristic morphology of conventional lipid vesicles formed by sonication. Transmission electron microscopy (TEM) showed that sonicated AC2 lipid dispersions are small homogeneous particles approximately 70-100 A in diameter. 1H NMR experiments using Mn2+ as a broadening reagent indicated that Mn2+ was accessible to all of the AC2 phospholipid headgroups in the AC2 lipid particles formed by sonication. The temperature dependence of 1H spin-lattice (T1) relaxation time measurements revealed that the motional activation energies increased from the choline headgroup to the end of the acyl chains of AC2 molecules in the AC2 lipid particles formed by sonication. Collectively these results demonstrate that AC2 forms micelles. NOESY experiments showed that the AC2 molecules forming the micelle structures have hindered motion compared to conventional short-chain phosphatidylcholine micelles. 31P NMR spectroscopy and TEM showed that the AC2 micelles extensively fuse into giant bilayer liposomes (single-layered) when the temperature is reduced from above to below the main phase transition temperature of AC2. This micelle-to-liposome transition is an irreversible process; increasing the temperature above the Tm does not cause the formation of micelles. Thus, a main finding is that AC2 micelles formed by sonication are not thermodynamically stable because they fuse into large unilamellar vesicles that are stable to further changes in temperature. These unusual membrane properties of sonicated AC2 dispersions may be important for the antiviral activity and metabolism of the phospholipids.

Antiviral Agents↗

PubMed1975

Mercuri-nitrophenol as a reporter group for the conformational change of hemoglobin.

One mole of horse hemoglobin tetramer reacts with 2 moles of 2-chloromercuri-4-nitrophenol (MNP) at beta 93 cysteine. The difference spectra between NMP-bound hemoglobin and hemoglobin, measured with the aid of ascorbic acid and ascorate oxidase [EC 1.10.3.3] as deoxygenation reagents, indicate that the pK of the phenolic hydroxyl group of MNP increases by 0.6 to 0.8 pH unit on deoxygenation of the hemoglobin. The Hill constant of the modified hemoglobin changes with pH. It decreases from about 2.4 at pH 6.8 to about 1.0 at pH 9.0 This effect of the reagent is interpreted as inherent to the reporter groups.

Animals↗

PubMed1983

An evaluation of the role of a pyroglutamyl peptidase, a post-proline cleaving enzyme and a post-proline dipeptidyl amino peptidase, each purified from the soluble fraction of guinea-pig brain, in the degradation of thyroliberin in vitro.

The degradation of thyroliberin (less than Glu-His-Pro-NH2) to its component amino acids by the soluble fraction of guinea pig brain is catalysed by four enzymes namely a pyroglutamate aminopeptidase, a post-proline cleaving enzyme, a post-proline dipeptidyl aminopeptidase and a proline dipeptidase. 1. The pyroglutamate aminopeptidase was purified to over 90% homogeneity with a purification factor of 2868-fold and a yield of 5.7%. In addition to catalysing the hydrolysis of thyroliberin, acid thyroliberin and pyroglutamate-7-amido-4-methylcoumarin the pyroglutamate aminopeptidase catalysed the hydrolysis of the peptide bond adjacent to the pyroglutamic acid residue in luliberin, neurotensin bombesin, bradykinin-potentiating peptide B, the anorexogenic peptide and the dipeptides pyroglutamyl alanine and pyroglutamyl valine. Pyroglutamyl proline and eledoisin were not hydrolysed. 2. The post-proline cleaving enzyme was purified to apparent electrophoretic homogeneity with a purification factor of 2298-fold and a yield of 10.6%. The post-proline cleaving enzyme catalysed the hydrolysis of thyroliberin and N-benzyloxycarbonyl-glycylproline-7-amido-4-methylcoumarin. It did not catalyse the hydrolysis of glycylproline-7-amido-4-methylcoumarin or His-Pro-NH2. 3. The post-proline dipeptidyl aminopeptidase was partially purified with a purification factor of 301-fold and a yield of 8.9%. The post-proline dipeptidyl aminopeptidase catalysed the hydrolysis of His-Pro-NH2 and glycylproline-7-amido-4-methylcoumarin but did not exhibit any post-proline cleaving endopeptidase activity against thyroliberin or N-benzyloxycarbonyl-glycylproline-7-amido-4-methylcoumarin. 4. Studies with various functional reagents indicated that the pyroglutamate aminopeptidase could be specifically inhibited by 2-iodoacetamide (100% inhibition at an inhibitor concentration of 5 microM), the post-proline cleaving enzyme by bacitracin (IC50 = 42 microM) and the post-proline dipeptidyl aminopeptidase by puromycin (IC50 = 46 microM). Because of their specific inhibitory effects these three reagents were key elements in the elucidation of the overall pathway for the metabolism of thyroliberin by guinea pig brain tissue enzymes.

Aminopeptidases↗

PubMed1984

Biosynthesis of long-chain alcohols by developing and regenerating rat sciatic nerve.

Cell-free preparations of rat sciatic nerve were found to catalyze the reduction of fatty acid to alcohol in the presence of NADPH as reducing cofactor. The reductase was membrane-bound and associated primarily with the microsomal fraction. When fatty acid was the substrate, ATP, coenzyme A (CoA), and Mg2+ were required, indicating the formation of acyl CoA prior to reduction. When acyl CoA was used as substrate, the presence of albumin was required to inhibit acyl CoA hydrolase activity. Fatty acid reductase activity was highest with palmitic and stearic acids, and somewhat lower with lauric and myristic acids. It was inhibited by sulfhydryl reagents, indicating the participation of thiol groups in the reduction. Only traces of long-chain aldehyde could be detected or trapped as semicarbazone. Fatty acid reductase activity in rat sciatic nerve was highest between the second and tenth days after birth and decreased substantially thereafter. Microsomal preparations of sciatic nerve from 10-day-old rats exhibited about four times higher fatty acid reductase activity than brain or spinal cord microsomes from the same animals. Wallerian degeneration and regeneration of adult rat sciatic nerve resulted in enhanced fatty acid reductase activity, which reached a maximum at about 12 days after crush injury.

Aging↗

PubMed1990

[Effect of dimethyladipimidate and dimethylsuberimidate on cell-cell adhesion in rat fibroblasts].

In a study performed to identify the molecular mechanisms which regulate cell to cell adhesion and contact inhibition in neoplastic and syngeneic normal cells of the rat we have observed that the adhesive capacity depends on the reagents used, either EDTA or trypsin, to release the cells from monolayer. Taking profit of this last property and of the possibility of blocking free -NH2 groups on membrane proteins with specific cross-linking reagents "in vitro", we have studied in this work the behaviour of the proteins of the cell coat involved in cell to cell adhesion of rat fibroblasts FG/2. The cross-linking reagents used were dimethyladipimidate (DMA) and dimethylsuberimidate (DMS). The cells were exposed to the reagents at 0 degrees C for 30'. Cell to cell adhesion was measured by determining the percentage of single cells labeled with 3H-leucine, adhering to a confluent monolayer at different incubation times. The inhibitory effect on cell to cell adhesion brought about by cross-linking reagents indicates that a) EDTA-released cells are more sensitive to both imides than those released with trypsin, b) DMA is more effective on trypsin-released cells and c) DMS is more effective on EDTA-released cells. Therefore, we conclude that the inhibition of adhesion by reaction with the two cross-linking reagents is more likely due to a stiffening of the molecules of the cell coat involved in the adhesion, rather than to the modification of -NH2 residues which should specifically participate to adhesive process.

Animals↗

PubMed1995

Characterization of N-ethylmaleimide-sensitive thiol groups required for the GTP-dependent fusion of endoplasmic reticulum membranes.

The GTP-dependent fusion activity of endoplasmic reticulum membranes is thought to be required for the structural maintenance and post-mitotic regeneration of the endoplasmic reticulum. This fusion is sensitive to the thiol-alkylating agent N-ethylmaleimide. In many intracellular fusion events N-ethylmaleimide-sensitivity is associated with a homotrimeric ATPase called N-ethylmaleimide-sensitive fusion protein or NSF. The addition of cytosol containing NSF is known to restore fusion activity to N-ethylmaleimide-treated membranes. We found that the inhibition of fusion of rat liver endoplasmic reticulum membranes (microsomes) by N-ethylmaleimide was not reversed by the addition of untreated cytosol. Fusion was also unaffected by treatment with a buffer known to remove NSF from membranes. Accordingly, no membrane-associated NSF was detected by immunoblot analysis. These data suggest that microsome fusion requires an N-ethylmaleimide-sensitive component distinct from NSF. This component was tightly associated with the membranes, so we used a number of chemical probes to characterize it in situ. Its thiol groups did not appear to be part of a GTP-binding site. They showed relatively low reactivity with sodium periodate, which induces the formation of disulphide bonds between proximate thiol groups. The thiols were not protected against N-ethylmaleimide by Zn2+, a potent inhibitor of fusion which is known to efficiently co-ordinate thiol groups. To characterize the topology of the fusion-related thiol groups we used bulky thiol-specific reagents prepared by conjugating BSA or 10 kDa aminodextran to the bifunctional reagent N-succinimidyl 3-(2-pyridyldithio)propionate. The inhibition of fusion by these reagents indicated that these thiols are highly exposed on the membranes. This exposure might be important for the function of these groups during GTP-triggered fusion.

Animals↗

PubMed1976

Determination of arginine in the reactive site of proteinase inhibitors by selective and reversible derivatization of the arginine side chain.

Reversible and selective modification of the guanidino group by 1,2-cyclohexanedione or 2,3-butanedione in borate buffer was applied to identify arginine residues in the reactive sites of proteinase inhibitors. The ability of the method to distinguish between arginine and lysine residues was examined. Trypsin inhibitors with arginine at the reactive site were almost completely inactivated within 2 h, e.g. the low-molecular weight inhibitors from soybeans (Kunitz), peanuts and porcine seminal plasma. Inhibitors of the lysine-type were not inactivated by 1,2-cyclohexanedione/borate, e.g. the bovine trypsin/kallikrein inhibitor, the trypsin inhibitors from cow colostrum, porcine pancreas, or snail epidermis (isoinhibitor K from Helix pomatia), and the human alpha1-proteinase inhibitor (alpha1-antitrypsin). However, 2,3-butanedione/borate does not show this high specificity. The method was applied to four high-molecular weight proteinase inhibitors from the albumin gland of the snail (Helix pomatia). All four inhibitors were subject to inactivation by the reagent, indicating an arginine residue at the reactive site. Evidence is given by NMR, UV, and titration data that a complex is formed from 1,2-cyclohexanedione and borate. Due to this complex formation, the amount of free carbonyl component is drastically decreased. Since 1,2-cyclohexanedione without borate lacks the high specificity for arginine residues, the borate complex of the reagent is presumed to be responsible for the high specificity. The new procedure for identification of reactive sites is based on a reversible modification of the guanidium group of the arginine residues.

Arginine↗

PubMed1983

Characterization of warm-reactive IgG anti-lymphocyte antibodies in systemic lupus erythematosus. Relative specificity for mitogen-activated T cells and their soluble products.

In addition to previously described cold-reactive IgM anti-lymphocyte antibodies maximally cytotoxic for resting cells at 15 degrees C, sera from patients with systemic lupus erythematosus (SLE) were found to contain a new type of antibody preferentially reactive at physiologic temperatures with mitogen-activated lymphocytes. This antibody lacked specificity for unstimulated lymphocytes, and was shown to be of the IgG class both by indirect immunofluorescence and in immunochemical experiments. Certain SLE sera also contained IgG antibodies with the capacity to develop plaques with mitogen-activated T lymphocyte preparations used in a reverse hemolytic plaque assay, indicating reactivity with products released by activated cells. The elimination of the ability of SLE sera to develop plaques after absorption with viable mitogen-stimulated lymphocytes, but not with resting cells, suggested that these antibodies were directed toward activation "neoantigen(s)" shed from the cell surface membrane. Surface membrane phenotype analyses performed by using a variety of monoclonal antibody reagents indicated that the plaque-forming cells (PFC) detected with SLE sera were activated T lymphocytes not restricted to single OKT4+, OKT8+, or Ia antigen+ subpopulations. Essentially all PFC expressed transferrin receptors. The present data raise the possibility that certain of the interesting effects of anti-lymphocyte antibodies on immunologic function in SLE may be mediated by interactions of these new type(s) of antibodies with activated lymphocytes or their products, rather than through blocking or depletion effects on resting precursor cells.

Antibody-Dependent Cell Cytotoxicity↗

PubMed2003

Antinociceptive effect of Phlomis olivieri Benth., Phlomis anisodonta Boiss. and Phlomis persica Boiss. total extracts.

In this study total extracts of three species of Phlomis (Lamiaceae), Phlomis olivieri, Phlomis anisodonta and Phlomis persica were tested for their antinociceptive effects using the visceral writhing test model in mice. Doses of 50, 100 and 150 mg kg(-1) of total extracts from three species of Phlomis were administered intraperitoneally 30 min before acetic acid 0.7% injection. The total extracts of P. olivieri, P. anisodonta and P. persica, respectively at doses of 150, 150 and 100 mg kg(-1), showed significant antinociceptive effects as indicated by 60.5, 54.3 and 56.7% (P<0.001) reduction of writhes, respectively in comparison to control. Results also showed that antinociceptive properties of P. olivieri, P. anisodonta and P. persica with ED(50) values of 88.21, 123.62 and 59.24 mg kg(-1), respectively, are comparable to that of indomethacin (5 mg kg(-1)). Preliminary phytochemical analysis by thin layer chromatography using specific reagents indicated the presence of iridoid glycosides and phenolic compounds such as flavonoid and phenylpropanoid glycosides in examined total extracts. The antinociceptive properties of examined total extracts could possibly be related to presence of iridoid glycosides and phenolic compounds.

Analgesics↗