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T Stigbrand

Publications and source records attributed to T Stigbrand.

At least 19 recordsLinked to original sources
PubMed1992

Differences in the proteinase inhibition mechanism of human alpha 2-macroglobulin and pregnancy zone protein.

Different conformational states of human alpha 2-macroglobulin (alpha 2M) and pregnancy zone protein (PZP) were investigated following modifications of the functional sites, i.e. the 'bait' regions and the thiol esters, by use of chymotrypsin, methylamine and dinitrophenylthiocyanate. Gel electrophoresis, mAb (7H11D6 and alpha 1:1) and in vivo plasma clearance were used to describe different molecular states in the proteinase inhibitors. In alpha 2M, in which the thiol ester is broken by binding of methylamine and the 'trap' is closed, cyanylation of the liberated thiol group from the thiol ester modulates reopening of the 'trap' and the 'bait' regions become available for cleavage again. The trapping of proteinases in the cyanylated derivative indicates that the trap functions as in native alpha 2M. In contrast, cyanylation has no effect on proteinase-treated alpha 2M. As demonstrated by binding to mAb, the methylamine and dinitrophenylthiocyanate-treated alpha 2M exposes the receptor-recognition site, but the derivative is not cleared from the circulation in mice. The trap is not functional in PZP. In native PZP and PZP treated with methylamine, the conformational states seem similar. The receptor-recognition sites are not exposed and removal from the circulation in vivo is not seen for these as for the PZP-chymotrypsin complex. Tetramers are only formed when proteinases can be covalently bound to the PZP. Conformational changes are not detected in PZP derivatives in which the thiol ester is treated with methylamine and dinitrophenylthiocyanate. The results suggest that the conformational changes in alpha 2M are generated by mechanisms different to these in PZP. The key structure gearing the conformational changes in alpha 2M is the thiol ester, by which the events 'trapping' and exposure of the receptor-recognition site can be separated. In PZP, the crucial step for the conformational changes is the cleavage of the 'bait' region, since cleavage of the thiol ester does not lead to any detectable conformational changes by the methods used.

Animals↗
PubMed1992

Expression of intestinal alkaline phosphatase in human organs.

Human intestinal alkaline phosphatase was immunohistochemically identified and localized in the pancreas, liver and kidney by use of a monoclonal antibody specific for intestinal alkaline phosphatase isozyme and by amplified biotin-streptavidin staining. In all the examined organs, the intestinal isozyme was found to be localized in the epithelial cells of ducts: bile ducts in the liver, distal convoluted tubules and collecting tubules in the kidney and ducts in the secretory epithelium in the pancreas. In the liver the antibody also stained some sinus-lining cells. In all the examined organs the endothelial cells of the capillaries and some vessels were stained. By use of immunoelectron microscopy, intestinal alkaline phosphatase was, as expected, found to be localized to the microvillar region of the small intestine. The isozyme was abundantly expressed in the apical area of the microvilli and in membrane remnants in the fuzzy coat. Capillaries and vessels in the submucosa were also stained, as well as small vesicles in the endothelial cells. The present investigation demonstrates the expression and localization of the intestinal alkaline phosphatase in several organs, though previously believed to be expressed only in the intestine.

Alkaline Phosphatase↗
PubMed1979

Placental alkaline phosphatase, alphafetoprotein and carcinoembryonic antigen in testicular tumors. Tissue typing by means of cytologic smears.

Indirect immunofluorescence and radioimmunoassay with specific rabbit antisera demonstrated the occurrence of alphafetoprotein (AFP), carcinoembryonic antigen (CEA) and placental alkaline phosphatase (PLAP) in primary testicular tumor cells. Embryonal carcinomas had AFP- and CEA-containing cells, sometimes PLAP. PLAP and sometimes CEA were found in seminoma cells. Sera from patients with advanced non-seminomatous tumors could contain any of these antigens or any combination of them. Sera from patients with seminomas had raised PLAP or CEA. PLAP appears to be a new marker for seminoma.

Adolescent↗
PubMed1979

Cell lines with spontaneous secretion of pregnancy-associated alpha 2-globulin.

Pregnancy-associated alpha 2-globulin (PA alpha 2G) was quantitated by radioimmunoassay in culture media from 34 exponentially growing human cell lines. Only 8/34 cell lines produced PA alpha 2G. The highest secretion was found in cell lines of histiocytic lymphoma origin while it was low in some carcinoma-derived lines. The results may support an assumption that PA alpha 2G is a normal cell product of B-lymphoid, monocytic and epithelial cells but may also simply indicate that ectopic PA alpha 2G production is especially common in tumors derived from such cells. The availability of PA alpha 2G-producing cell lines should facilitate studies of the immunoregulatory role of this protein.

Alpha-Globulins↗
PubMed1979

Isolation and partial characterization of intermediate filament protein (skeletin) from cow heart Purkinje fibres.

The intermediate filament protein skeletin from cow heart Purkinje fibres was purified to homogeneity by a selective extraction procedure and gel chromatography in the presence of sodium dodecyl sulphate. Monospecific antibodies were obtained by immunisation of rabbits with the sodium dodecyl sulphate-skeletin complex, and rocket electrophoresis made it possible to quantify the concentration of protein. The skeletin monomer has a molecular weight of 55 000. Amino acid analysis revealed that skeletin has a high content of glutamic acid, aspartic acid, alanine and leucine, together constituting more than 50% of the molecule. The isoelectric point is determined as 6.35. Skeletin is insoluble at pH 4--6 in the absence of detergent and shows increasing solubility at higher and lower pH. The biochemical characteristics are discussed in relation to the cytoskeletal function of the filaments. Comparison with intermediate-sized filament protein of other tissues show certain important similarities suggesting that the filaments may share a common evolutionary ancestry.

Amino Acids↗
PubMed1979

Association between Duffy blood groups and serum level of the pregnancy zone protein.

In a previous study of psoriatic patients we found increased serum levels of the pregnancy zone protein (PZ) in individuals of blood groups O and Fy(a-). In this study we found an association between the PZ serum level and the Fy(a-) blood group also in young healthy males. Thus the association between the PZ serum level and Duffy blood groups appears to apply to both normal and pathological conditions.

ABO Blood-Group System↗
PubMed1979

Skeletin immunoreactivity in heart Purkinje fibers from several species.

Ever since its discovery, the identification of the specialized conducting system of the heart has been a matter of debate. In some species, a main distinguishing feature under the electron microscope, as compared with ordinary myocytes, is the presence of large pools of juxtanuclear filaments, so called intermediate or skeletin filaments. In the present study, we have adopted the indirect immunofluorescence method and anti-skeletin antisera for the identification of the ventricular conducting system in several species. It was found that anti-skeletin reactivity generally exceeded that of ordinary myocytes. The degree of immunofluorescence could be related to a previous classification model of the differentiation of the conducting cells. It is suggested that skeletin is highly conserved throughout phylogeny and that anti-skeletin may serve as an additional tool for the identification of conducting cells at the light microscopic level.

Animals↗
PubMed1979

A new and sensitive method for quantifying and comparing the biological potency of varius estrogens in man.

The serum level of an estrogen-inducible plasma protein was followed by a radioimmunoassay in groups of women during treatment with various estrogens. After an initial increase, the mean value for the serum concentration was stable. The plateau level after six months of treatment was taken as a parameter of estrogenic potency. Eleven different hormonal preparations were compared and an estrogen index was constructed.

Contraceptives, Oral, Sequential↗
PubMed1979

Serum levels of placental alkaline phosphatase in high-risk pregnancies.

A recently developed radioimmunoassay (RIA) for placental alkaline phosphatase (paf) was used to estimate the maternal serum levels of the enzyme in 51 women with various complications of pregnancy. The results were compared with a reference group of 242 women with apparently normal pregnancies. Women with intrauterine growth retardation (IUGR) or severe or mild preeclampsia had significantly low weight of the fetoplacental unit. Simultaneous determinations of PAF in maternal serum and the urinary total estrogen/24 hr gave a clear differentiation of the IUGR group from the other pregnancies at risk. All PAF values from risk pregnancies were below the mean values of normal pregnancy.

Alkaline Phosphatase↗
PubMed1978

Cytoskeletal filaments of heart conducting system localized by antibody against a 55,000 dalton protein.

Cow heart conducting cells characteristically contain cytoplasmic intermediate-sized filaments. We report here the preparation of a specific antibody to a 55,000 dalton protein of isolated cow Purkinje fibres. Confirmation has been obtained that these filaments consist of the 55,000 dalton protein, using the indirect immunofluorescence technique. Cross-reaction is seen with vascular endothelium and smooth muscle cells of various origin, suggesting close identity of different types of intermediate-sized filaments.

Animals↗
PubMed1978

A double antibody solid phase radioimmunoassay for placental alkaline phosphatase.

A solid-phase "direct" radioimmunoassay for determination of placental alkaline phosphatase in serum was developed. The assay is highly sensitive, with a minimum detectable dose of 9 ng protein per ml. The specificity for the placental type of the enzyme, in comparison to other serum alkaline phosphatases, was found to be convincing. The choice of genetic types of either placental alkaline phosphatase or antiserm was found not to influence the radioimmunoassay. With the described technique the serum concentration of this enzyme during normal pregnancy was measured. A 25-fold increase from low levels during the first trimester up to 252 +/- 70 ng/ml (mean +/- S.D.) in gestation week 40 was observed.

Alkaline Phosphatase↗
PubMed1978

Catalytic properties and stability of three common variants of placental alkaline phosphatase.

Three placental alkaline phosphatases purified to homogeneity, i.e., the F, I, and S variants, were investigated for catalytic and stability properties. All three forms of the enzyme were found to have almost identical pH optima (10.7--10.8), similar sensitivity to the uncompetitive inhibitors L-phenylalanine (70%) and L-leucine (30%), and identical Km values against p-nitrophenylphosphate, beta-glycerophosphate, and alpha-naphthylphosphate. Significant differences among the three types were observed in thermal stability. The F variant was found to be most stable and the I variant most labile at 79 C. At 70 C all three forms were stable.

Alkaline Phosphatase↗