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At least 1,711 records · Page 95Linked to original sources
PubMed1988

[Synthetic inhibitors of serine proteinases. 34. The effect of modification of the amidino function of N-alpha-substituted 4-amidinophenylalanine amides on inhibitory activity].

Cyclic amides of N alpha-arylsulfonylated 4-amidinophenylalanine are selective inhibitors of thrombin. The exchange of the amidino function for an aminomethyl residue does not influence the selectivity and potency of their inhibitory activity. In contrast, the modification of the amidino function of the N alpha-arylsulfonylaminoacylated compound N alpha-(2-naphthylsulfonylglycyl)-4-amidinophenylalanine piperidide results in a drastic loss of inhibitory activity. Only the oxamidino derivative possesses considerable high affinity for thrombin. Obviously, in tight binding inhibitors of thrombin structural variation results in any case in a loss of inhibitory activity.

Amidines↗
PubMed1986

Immunological characterization of the vitellogenic proteins in Squilla mantis hemolymph (Crustacea, Stomatopoda).

The femal specific proteins (FSP) identified in the hemolymph of Squilla mantis females are here proven to be vitellogenins (VTG) by immunological and electrophoretical methods. VTG 1 which has a higher molecular weight (MW) and only one central form, both in hemolymph and eggs, can be detected immunoelectrophoretically. VTG 2 and 3 have similar lower MW and are immunologically closely related, their slightly cathodic precipitation are fusing with the slightly anodic form. A further cathodic shift of the double arc occurs in the corresponding egg proteins. The VTGs are forms of yolk proteins which are transported in the hemolymph from the site of synthesis to the ovary where they undergo structural variations without involving a change of MW or of their number.

Animals↗
PubMedDate not supplied

Synthesis of N-aryl-N'-[2-phenyl-3-quinazoline(3H)-4-one] acylthiourea derivatives as anticonvulsants.

By the reaction of [2-phenyl-3-quinazolineo (3H)-4-one] acyl isothiocynates and appropriate aryl amines in acetone, 24 new compounds, having a substituted thiourea grouping at the 3-position of the quianozolone moiety, were prepared. All compounds, except two, showed different degree of protection against pentetrazol induced seizures test in albino mice. While studying the effect of structural variation no definite pattern could be observed due to variations in 1-aryl moiety, but it was noticed that generally the branching or lengthening of 3-acyl chain either diminishes or does not effect the activity.

Animals↗
PubMed1979

Structural studies on the murine Ia alloantigens. VI. Evidence that both subunits of the I-A alloantigen are encoded by the I-A subregion.

The alpha and beta subunits of the murine I-A alloantigens from several H-2 haplotypes were examined by comparative tryptic peptide mapping by using double label (3H and 14C) techniques. Significant structural variation between alleles was detected in both subunits. Tryptic digests of the alpha polypeptides from s, b, and d showed only 65% co-elution with k; beta-chains from s, b, d, and r were about 50% similar to the k beta subunit. Peptide analysis of the Ak subunits from intra-H-2 recombinant strains indicated that both the alpha and beta polypeptides are encoded within the I-A subregion.

Animals↗
PubMed1978

[Histopathological diagnosis in the animal experiment (author's transl)].

Spontaneous and experimentally induced organ alterations in laboratory animals do not always coincide with comparable lesions in human pathology. In addition, the discrimination between experimental tissue alterations and non-pathological structural variations may be difficult. In such cases a clear-cut separation can only be achieved by a proven dose-response relation, which, however, requires a quantitative or semiquantitative registration of histological findings.

Animals↗
PubMed1977

Affinity chromatography of serum proteins using immobilized lectin from Vicia faba.

When human serum is applied to a column of Sepharose-insolubilized lectin from Vicia faba, some serum proteins are bound which can be eluted by means of 0.1 M glucose solution. These proteins are parts of the immunoglobulins IgA, IgG, IgM, and the alpha2-macroglobulin. These particular types of serum protein are bound specifically, due perhaps to some structural variation in the carbohydrate moieties they contain.

Blood Proteins↗
PubMed1983

Structural heterogeneity of the human Ia molecular pool as detected by cross-reacting mouse monoclonal antibodies.

Three monoclonal antibodies (Mab), H39.49.5, H40.242.3, and H40.164.3, produced in an A.TH anti-A.TL system and reacting with determinants expressed either on I-Ak, on I-Ek, or on I-Ak and I-Ek molecules, respectively, have been used to analyze, at the structural level, the molecules of the human Ia pool against which they cross-react. The results indicate that the human Ia pool can be dissected out by the use of the A.TH anti-A.TL Mab in distinct families, which display structural variations not only among each other but also with respect to the previously defined NG1 and NG2 Ia subsets. In two distinct Ia pools analyzed (from Raji cells: HLA-DR 3,W6, and from LG-2 cells: HLA DR 1,1), the three A.TH anti-A.TL cross-reacting antibodies recognized molecules in which the allelic polymorphism was confined to the beta subunits. Moreover, within the same Ia pool, the alpha subunits as well as the beta subunits were shown to be different from each other. These results are discussed in the context of the present knowledge of the heterogeneity of the human Ia pool and of the possible similarity between gene products of the mouse H-2-I region and the human HLA-D counterpart.

Antibodies, Monoclonal↗
PubMed1983

Clonal analysis of H-2Kb + TNP recognition by T cells with the use of H-2Kbm mutants and H-2Kb-specific monoclonal antibodies.

Eleven long-term cytotoxic T lymphocyte (CTL) clones derived from C57BL/10 T cells sensitized in vivo and in vitro with trinitrobenzene sulfonate- (TNBS) treated syngeneic cells were all restricted to the K end of H-2b. The fine specificity of these CTL clones was analyzed by using H-2Kbm mutant target cells and H-2Kb-specific monoclonal antibodies (mAb). Seven distinct patterns of reactivity of the T cell clones could be observed with the use of six H-2Kbm mutant target cells. Further heterogeneity could be detected in terms of the ability of anti-Lyt-2 mAb to inhibit CTL activity. Cross-reactivity between H-2Kb + TNP and H-2Kbm + TNP was observed for all clones tested for bm5 and bm6, but less frequently for bm3 (8/11), bm8 (7/10), bm4 (4/11), and bm1 (3/11). It was further observed that amino acid substitutions located in the first domain only (one clone), or in the second domain only (six clones), or in either the first or the second domain (three clones) of the H-2Kb molecule could affect target cell recognition by a given T cell clone. the latter type of reactivity suggested that some clones recognized "conformational" determinants of the H-2 molecule, or that amino acid substitutions in one domain might influence the structure of the next domain. One H-2Kb + TNP-reactive clone exhibited a heteroclitic behavior with decreasing avidities for target cells expressing H-2Kbm8 + TNP, H-2Kb + TNP, and H-2Kbm8, which further extends the various patterns of T cell cross-reactions observed within a given class of MHC products. The use of H-2Kb-specific mAb in blocking studies as an attempt to define further the H-2Kb epitopes recognized by CTL clones indicated that: a) TNBS treatment may affect the antigenicity of the H-2Kb molecule as assessed by some mAb; and b) that the T cell clone-target cell interaction may or may not be inhibited by a given mAb, depending on structural variations of the H-2Kb molecule (use of H-2Kbm mutants) that do not affect the interaction itself. These results indicate that this type of analysis does not permit correlation of serologic- and T cell-defined epitopes.

Animals↗
PubMed1984

Changes in the Ir gene controlled response phenotypes in mice of the Ap and Ak family of alleles expressing naturally occurring variant molecules.

Several wild-derived H-2 haplotype mice were recently shown by serology and tryptic peptide fingerprinting to express I-region A molecules closely related to the Ap and Ak molecules of the laboratory strains. To determine if such naturally occurring minor structural variations in the A molecule alter Ir gene-controlled responsiveness, we examined the immune responses of these strains after primary immunizations to three synthetic polypeptide antigens: G60Phe40, GLPhe9, and GAT10. Inbred strains carrying the Ap (or Aq) allele are known to be high responders to G60Phe40 and GLPhe9 but low responders to GAT10. Strains expressing the Ak allele are classified as low responders to G60Phe40 and GLPhe9, but high responders to GAT10. Of seven strains examined belonging to the Ap family, one (B10.CAS2) failed to respond to either G60Phe40 or GLPhe9 as measured by antibody production and T cell proliferation. In addition, two strains (B10.STC90 and W12A) of the Ak family were found to be of responder phenotype to GLPhe9. Both GLPhe9 responses resulted from the introduction of new E beta genes into the I region through naturally occurring intergenic recombination between A beta A alpha and E beta. All strains of mice in the Ak family proved to be of the high responder phenotype in their responses toward GAT10. These results contrast strongly with known patterns of alloreactivity against the variant Ap and Ak molecules.

Alleles↗
PubMedDate not supplied

[Synchronous (synphaseous) additive models for mitochondrial ATP synthetase complex and for other energy transducing systems of cells (a hypothesis)].

There exist some energy transducing enzymes containing immobile molecules of substrates which are not exchangeable during protein functioning. According to the proposed models the immobile substrates are localized at the "idle" (or "partial" or "imitational") catalytic sites, which differ from normal ("working") active sites of enzymes. Only some steps of a complete reaction sequence which take place at the "working" sites are carried out at the "idle" sites. On the other hand, cyclic conversion of the immobile substrate at an "idle" catalytic site may include some steps which are absent in the "working" site cycle. The occurrence of identical steps on the "idle" and "working" catalytic sites allows to synchronize their action through conformational interconversions of tightly packed and structurally related "idle" and "working" subunits of the enzyme. The presence of covaletly bound substrates or substrates localized in closed cavities of the "idle" sites allows to synchronize the action of many monomers containing such sites due to the absence of the rate-limiting step of simultaneous saturation of many catalytic sites by substrate molecules from solution, and due to the lack of substrate inhibition on the "idle" sites. The functions of the "idle" sites are miscellaneous e.g. in ion-transporting systems these sites are directly involved in ion translocation. In the actomyosin complex the "idle" sites imitate conformational alterations of "working" sites, thus allowing synchronous functioning of the polymeric structure. Variations in the number of the "idle" sites operating simultaneously with one "working" site allow to regulate some parameters of enzymatic processes, e.g. the stoichiometry (number of transported ions per ATP hydrolysed (or synthesised) or electron-transported, or hv-absorbed ones) for ion transported systems or the ratio (velocity of contraction to developed efforts) for the actomyosin complex.

ATP Synthetase Complexes↗
PubMed1983

[Forms and factors of the variability of paranasal sinuses].

The form, structural variations, sex variations (connected with zygosityz), right and left positions of the sinuses were studied according to the data obtained while measuring the contours of the frontal, sphenoid and maxillary sinuses in the cranial roentgenograms made in the frontal and sagittal projections. By means of the twin method, relationship of the hereditary and environmental influences on the sinus formation was estimated. The data obtained in 111 Ukrainians (30--60 years of age), inhabitants of Vinnitsa region, mono- and dizygote twins of both sex were used. Greater dimensions in the male sinuses and a high variability of their size not connected with sex were stated. Among women the dizygote twin had larger dimensions than the monozygote ones. The sinus size is characterized by a predominant right-sided asymmetry. The hereditary effect is clearly seen in the sinus paranasales formation. A decreasing hereditary influence noted in the maxillary sinus is considered as a dependence of its dimensions on the state of the masticatory apparatus.

Adult↗
PubMed1984

Segmental staining of the murine nephron by monoclonal antibodies directed against the GP-2 subunit of laminin.

Monoclonal antibodies to GP-2, the 220,000-dalton subunit of laminin, were used in an immunohistologic study to investigate structural variations in basement membranes. Mouse kidney was used because of the wide range of basement membranes represented. Two rat/mouse monoclonal antibodies, designated LAM-I and LAM-II were compared with rabbit polyclonal anti-GP-2 in a light and electron microscopic study that identified nephron segments by morphology, by topography, and by the use of markers specific for individual segments. LAM-I staining is demonstrable on all tubular and glomerular basement membranes but not on those of blood vessels or smooth muscle, differing in this respect from anti-GP-2. LAM-II staining is confined to the basement membranes of the convoluted portion of proximal tubule segments (S1 and S2), not the straight (S3) portion; to the thin limb and the thick ascending limb of Henle's loop, but not distal convoluted tubules or collecting ducts. The heterogeneity of GP-2 localization may be due to differing conformations of the molecule at these sites.

Animals↗
PubMed1984

Co-elution of type I and type II cAMP-dependent protein kinase holoenzymes in high salt fractions from DEAE-cellulose.

Post-mitochondrial supernatants from adult and neonatal mouse lung were each separated using DEAE-cellulose chromatography, and fractions were assayed for cAMP-dependent kinase activity and photoincorporation of the analog, 8-azido-cyclic adenosine 3':5'-monophosphate. Although there is no significant developmental differences in the amount of kinase activity which elutes in these high salt or DEAE peak II fractions, such fractions derived from neonatal lung contain only half as much photodetectable regulatory subunit of the type II protein kinase isozyme (RII) as do corresponding fractions from the adult. Much of the kinase activity associated with these neonatal DEAE peak II fractions may actually be due to the type I holoenzyme. Significant amounts of photodetectable regulatory subunit of the type I protein kinase isozyme (RI) co-elute with this peak of type II kinase activity, and several lines of evidence suggest that much of this RI exists in a holoenzyme state. Incubation of these peak II fractions with cAMP prior to a second elution from DEAE-cellulose causes much of the RI to elute at lower salt concentrations characteristic of the free RI subunit. After sucrose gradient sedimentation of peak II fractions, RI cosediments with the peak of cAMP-dependent kinase activity. Finally, kinase activation by cAMP is biphasic, suggesting that both the type I and II holoenzymes contribute to the kinase activity in the type II peak. Two-dimensional gel electrophoresis of photolabeled proteins does not suggest any structural difference between RI subunits present in various DEAE fractions. The elution of the type I holoenzyme over a range of salt concentrations may be due to structural variations in the C subunit of the type I isozyme or possibly to the stable association of the type I holoenzyme with other molecules in the cell.

Aging↗
PubMed1978

Structural changes in the thyroid gland of buffalo following administration of thiouracil.

The effects of a goitrogen (thiouracil) on the structural variations of the thyroid gland were studied in male buffalo calves. Following the treatment, the thyroid became enlarged and both the weight and the size of the gland were significantly increased (P less than 0.01). Hyperplasia and hypertrophy of the gland were correlated with a significant increase of thyroidal uptake of 131I. The height and number of the follicular cells were significantly increased (P less than 0.01). The follicles were small and had vacuolations in the colloid. The colloid content of the follicles became reduced. The vascularity of the gland was appreciably increased.

Animal Feed↗
PubMedDate not supplied

Cytology of the exfoliative layer in normal and diseased vulvar skin: correlation with histology.

The vulvae of 464 patients were studied by cytologic and/or histologic examination. Of these, 286 patients had clinically normal vulvae and 178 patients, diseased vulvae. Histology revealed 47 benign, 20 precancerous and 111 malignant lesions. Structural variations of the vulvar stratum corneum could be classified into five categories: orthokeratosis, hyperkeratosis, parakeratosis, dyskeratosis and tumor penetration. Orthokeratosis, hyperkeratosis and parakeratosis were present in the normal vulvae as well as in benign conditions; they were characterized cytologically by anucleated horny squames or by parakeratotic cells. Dyskeratosis usually indicated precancerous or malignant conditions but was also observed, although in mild form only, in certain benign lesions, e.g., acute inflammation and condyloma acuminatum. Nevertheless, evidence of dyskeratotic cells in vulvar smears should cause concern because vulvar cancer frequently is covered by a continuous horny (dyskeratotic) layer. Only half of the malignant vulvar lesions showed tumor penetration through this superficial layer, with subsequent exfoliation of tumor cells.

Adult↗
PubMed1980

[Evidence of morphological modifications induced by theophylline in the urinary bladder epithelium of Rana esculenta].

This preliminary work concerns the morpho-functional action induced by Theophylline on bladder epithelium. The epithelium treated with Theophylline shows important structural variations. The whole tissue thickness appears reduced with cell disposed in monostratified layer. They show a light grade of swelling with nucleus and cytoplasm less evident and boundary less marked. It is important to note that the permeability of the epithelium does not appear modified.

Animals↗
PubMedDate not supplied

[Criticism of the current theories concerning the formation of the immunological repertory].

Application of the probability calculus to the variational structure of the immunoglobulins leads to demonstrate the impossibility of the random production of the repertory's antibodies. Physical and Cybernetic considerations lead, instead, to demonstrate the necessary existence of aspecific recognition of the antigen, i.e. of the antigen's activity. Application of the theory of stochastic convergence, at last, leads to demonstrate that, if there would be a connection between this aspecific recognition and the antibody's production, the latter would be possible. This connection, as a consequence, must exist.

Antibody Formation↗
PubMed1978

Structural studies on the murine IA alloantigens. II. Molecular weight characterization of the products of the I-A and I-E/C subregions.

Murine splenocytes were radiolabeled with 3H- and 14C-amino acids; the Ia alloantigens encoded by the I-A and I-E/C subregions were isolated by immunoprecipitation and analyzed for structural variation by polyacrylamide gel electrophoresis. The I-A subregion products (k, d, and b haplotypes) are composed of two polypeptides, alpha and beta, with m.w. of 34,000 and 26,000 daltons, respectively. Haplotype-associated differences in m.w. were detected in the I-E/C products of the k, r, p, and d haplotypes. The alpha and beta chains of E/Ck and E/Cr are 34,000 and 28,000 daltons, respectively; E/Cp and E/Cd molecules are composed of 31,000 and 29,000 dalton polypeptides. Thus, there is both subregion (I-A vs I-E/C) and haplotype (E/Ck, E/Cr vs E/Cd, E/Cp) associated variation in the m.w. of the Ia alloantigens. Additionally, the covalent vs noncovalent association of the Ia subunits was examined and it was found that the alpha and beta chains of both I-A and I-E/C are not covalently associated. However, the I-A alpha and beta chains tend to associate through disulfide bonds during detergent lysis; the presence of alkylating agents during cell lysis prevents this association, and only free alpha and beta chains are observed under nonreducing conditions.

Animals↗