Biomedical subjects

T Stigbrand

Publications and source records attributed to T Stigbrand.

At least 145 records · Page 8Linked to original sources

PubMed1987

A hidden antigenic determinant on membrane-bound human placental alkaline phosphatase.

Two sets of monoclonal antibodies (mAbs) specific for human placental alkaline phosphatase (PLAP) were compared. One set of four mAbs was generated against solubilized and purified PLAP; the other set of seven mAbs was generated against the malignant cell line Hela TCRC-1 in which PLAP is an ectopically synthesized membrane-bound enzyme. Double immunodiffusion and competitive enzyme-linked immunosorbent assays were used to examine the relative spatial arrangement of the antigenic determinants to which each of the eleven mAbs binds. Significant differences in immunoreactivity of the antibodies were demonstrated. The mAbs to the solubilized and purified enzyme bound in either of two regions of the molecule. By contrast, all of the mAbs to PLAP as presented on the tumor cell surface bound in only one of these two regions. One of the major antigenic determinants on the solubilized enzyme is apparently unavailable for recognition by immunoreactive cells during immunization with whole cells. Furthermore, when mAbs are generated to this region using purified PLAP as the immunogen, they do not recognize membrane-bound PLAP. The 'hidden' determinant can be exposed in vitro after partial solubilization using butanol to extract the enzyme from HeLa TCRC-1 cells and subsequent treatment with 0.5% Nonidet P-40 detergent. The results of this study have implications for the potential use of mAbs in studies of other cell surface antigens and in tumor immunolocalization and drug targeting.

Alkaline Phosphatase↗

PubMed1987

Effects of oestrogen and human growth hormone on pregnancy-associated plasma proteins in the rat.

The serum concentrations of pregnancy-associated murine protein-1 (PAMP-1), acute phase alpha 2-macroglobulin, albumin, transferrin, and complement factor 3(C3) were followed in male rats during continuous infusions of oestradiol-17 beta and human growth hormone. Three different patterns of protein response could be distinguished. A distinct acute phase response without any additive influence of the given hormones was recorded for alpha 2-macroglobulin, whereas the levels of albumin, transferrin and C3 were virtually unaffected throughout the experiment. Growth hormone gave a rapid and pronounced increase of PAMP-1 levels, whereas the response to oestradiol of this 'steroid-sensitive' protein was significantly weaker and delayed. It is suggested that the apparent oestrogenic influence on certain pregnancy-associated plasma proteins is mediated via growth hormone.

Animals↗

PubMed1987

Tumor markers in mammary carcinoma. An evaluation of carcinoembryonic antigen, placental alkaline phosphatase, pseudouridine and CA-50.

In 104 patients with breast cancer, carcinoembryonic antigen (CEA), placental alkaline phosphatase (PLAP) and the carbohydrate antigen CA-50 were analysed in serum. Excretion of the modified nucleoside, pseudouridine, was analysed in urine. The patients were subdivided in three different clinical stages according to disease manifestations. Levels of CEA and pseudouridine correlated to clinical stage and 58 per cent of the patients with distant metastases had elevated levels of CEA, compared with 36 per cent for pseudouridine. For PLAP and CA-50, the levels did not show any clear correlation to clinical stage. Increased activity of PLAP correlated strongly to tobacco smoking. A decrease in the level of CEA was observed following radical mastectomy. Increase in CEA levels predicted relapse in 5 out of 14 patients within about 3 to 6 months. In patients with tumor manifestations, elevated CEA levels predicted an inferior prognosis compared to those with ordinary levels.

Alkaline Phosphatase↗

PubMed1986

Phenotypes of placental-type alkaline phosphatase in seminoma sera as defined by monoclonal antibodies.

PLAP-like enzymes could be detected in serum of patients with primary testicular tumors, in particular seminomas. The use of a panel of monoclonal antibodies (MAbs) permitted typing into 6 different testicular serum phenotypes, of which one appeared similar to a placental type (II) and 2 have not been previously described. Most tumor sera belonged to type I, as described for seminoma tissues. With a more advanced tumor the mean serum PLAP-like levels increased. After operation, after radiotherapy or with no evidence of disease lower or non-detectable enzyme levels were found. In typing the tissue PLAP-like antigen in serum of the same patient or sera from recurrences of a seminoma in the same patient, the same phenotypes of PLAP-like antigen were usually but not always found. None of the 6 phenotypes appeared to confer a poorer prognosis. We conclude that the expression of PLAP-like antigen is eutopic and is enhanced by testicular malignancy, especially in seminoma cells.

Adult↗

PubMed1986

Improved radioimmunolocalization of carcinomas using Fab fragments with anti-CEA specificity.

A model system with human colonic grafts containing carcinoembryonic antigen (CEA) in nude mice was used to improve specificity and sensitivity of the radioimmunolocalization method. Monoclonal antibody MAb I-38S1 and monkey anti-CEA appeared to have high in vitro and in vivo specificity. Fab fragments of MAb I-38S1 improved localization ratios. A reduced time for optimal immunolocalization was obtained with Fab compared with MAb of the same specificity. Combinations of Fab:s, vasoactive compounds or anti-IgG treatment to reduce background levels did not further improve speed of localization or sensitivity.

Alkaline Phosphatase↗

PubMed1985

Structural comparisons of two allelic variants of human placental alkaline phosphatase.

A simple immunosorbent purification scheme based on monoclonal antibodies has been devised for human placental alkaline phosphatase. The two most common allelic variants, S and F, have similar amino acid compositions with identical N-terminal amino acid sequences through the first 13 residues. Both variants have identical lectin binding properties towards concanavalin A, lentil-lectin, wheat germ agglutinin, phytohemagglutinin and soybean agglutinin, and identical carbohydrate contents as revealed by methylation analysis. CNBr fragments of the variants demonstrate identical high performance liquid chromatography patterns. The carbohydrate containing fragment is different from the 32P-labeled active site fragment and the N-terminal fragment.

Alkaline Phosphatase↗

PubMed1985

Antigenic determinants of pregnancy-associated alpha 2-glycoprotein and alpha 2-macroglobulin defined by poly- and monoclonal antibodies.

Human alpha 2-macroglobulin and pregnancy-associated alpha 2-glycoprotein (PA alpha 2G) share several physicochemical characteristics. By the use of unabsorbed or absorbed polyclonal antibodies to these antigens, the existence of common epitopes in these molecules were demonstrated in crossed immunoelectrophoresis. Two monoclonal antibodies out of 9 raised against purified PA alpha 2G were demonstrated to react with both antigens, indicating close immunochemical relatedness between these macroglobulins. The findings might have functional implications.

Animals↗

PubMed1985

On the value of placental alkaline phosphatase as a marker for gynecological malignancy.

A sensitive catalytic assay for placental alkaline phosphatase (PLAP) was used to quantify enzyme levels in sera from women with malignant gynecological tumors, i.e. cervical carcinoma, ovarian carcinoma and carcinoma of the breast. Values were compared with those of a reference group of 155 healthy individuals. In this group, basic mean levels of the enzyme amounted to 0.06 +/- 0.08 mumoles X min-1 X 1(-1) (mean +/- SD), which corresponds to 0.3 +/- 0.4 ng/ml (mean +/- SD) purified placental alkaline phosphatase. Enzyme levels were not significantly affected by age, whereas sex gave slightly higher values for women in all age groups. This difference was statistically significant (p less than 0.001). The discriminating capacity of PLAP as a tumor marker was analysed with this assay and compared in sensitivity with a radio-immunoassay. A cut-off level of 0.2 mumoles X min-1 X 1(-1), corresponding to 1 ng/ml enzyme protein as measured by the radio-immunoassay, detected 23-68% of the tumor patients, giving false-positive results from the control group in the order of 5%. Corresponding values at a cut-off level of 0.3 mumoles X min-1 X 1(-1) (1.5 ng/ml) gave values 20-44% and 2%, respectively. The present investigation emphasizes that sensitivity in assays of placental alkaline phosphatase, whether catalytic or immunological, must not exceed ng-level.

Adolescent↗

PubMed1984

Eutopic expression of placental-like alkaline phosphatase in testicular tumors.

Very high levels of placental-like alkaline phosphatases (PLAP-like enzymes) were observed in tissues from 13 typical seminomas. Four tumors with seminoma components contained these enzymes to varying degrees, and other testicular tumors had them in smaller or non-detectable amounts. Analysis using monoclonal antibodies produced against the common placental alkaline phosphatase (PLAP) phenotypes and enzyme inhibition studies with amino acids and peptides showed the PLAP-like enzymes present in seminoma to be similar to those PLAP-like enzymes which are expressed in lower amounts in two embryonal carcinomas and in trace amounts in normal testicular tissue. These similarities suggest that the increased expression of PLAP-like enzymes in seminomas results from enhanced eutopic expression of enzymes found in normal testis.

Alkaline Phosphatase↗

PubMed1984

Monoclonal antibodies block the trypsin cleavage site on human placental alkaline phosphatase.

Three of eleven monoclonal antibodies (mAbs) to human placental alkaline phosphatase (PLAP) were shown to block cleavage by trypsin at the only proteolytically sensitive site on the native molecule. These results illustrate the potential importance of using mAbs to restrict proteolysis of proteins, in general, and serve as a novel means to identify the relative locations of antigenic determinants.

Alkaline Phosphatase↗

PubMed1984

Partial characterization of the oligosaccharides of mouse thymocyte Thy-1 glycoprotein.

Four glycopeptides (I, IIA, IIB, III) with different oligosaccharide structures were isolated from purified mouse thymocyte Thy-1 glycoprotein. The glycoprotein was digested with Pronase, and the glycopeptide fraction was isolated by gel filtration and acetylated with [3H]acetic anhydride. The different glycan structures were separated by affinity chromatography on concanavalin A-Sepharose 4B and lentil lectin-Sepharose 4B. Size determinations of intact and exoglycosidase- and endoglycosidase-digested glycopeptides were performed by gel filtration on Bio-Gel P-6, calibrated with glycopeptides of known structure. On the basis of these experiments and on the behaviour of the glycopeptides on the lectin columns, the following structures of the oligosaccharide chains were proposed: I, triantennary 'complex-type' with terminal fucose; IIA, biantennary 'complex-type' without fucose; IIB, biantennary 'complex-type' with fucose; III, a mixture of 'high-mannose' chains containing either five or six mannose residues (approx. 50% of each). Amino acid analysis of the glycopeptides showed that the predominant oligosaccharide at glycosylation-site Asn-23 was of 'high-mannose' type, whereas the other two sites (Asn-75 and Asn-99) were glycosylated with 'complex-type' chains. Both these sites were shown to be variably glycosylated. The major glycans linked to Asn-75 were of structures I and IIB, whereas all three 'complex-type' chains were represented at Asn-99. The results presented explain the previously reported carbohydrate heterogeneity of thymocyte Thy-1 glycoprotein.

Amino Acids↗

PubMed1984

Tumour and cellular localization by use of monoclonal and polyclonal antibodies to placental alkaline phosphatase.

Monoclonal and polyclonal antibodies against placental alkaline phosphatase (PLAP) were evaluated for tumour immunolocalization of human PLAP-producing Hep 2 tumours in nude mice. The antibodies were labelled with 125I and injected i.p. in mice with developing Hep 2 tumours. The distribution of 125I-anti PLAP in various tissues showed that the labelled antibody was enriched in the tumour, the mean concentration ratio being 7.1 and 6.8 for polyclonal and monoclonal antibodies, respectively. A PLAP negative tumour (RD) showed a mean ratio of 1.2. There was a positive correlation between PLAP content and uptake of labelled antibody in the tumours. Hep 2 tumour cells in tissue culture showed 100% positivity for PLAP, while imprints of the tumour after passage in nude mice showed 40-50% positivity. PLAP offers potential as a useful marker for localizing tumours in humans.

Alkaline Phosphatase↗

PubMed1984

Placental alkaline phosphatase compared with human placental lactogen and oestriol in high-risk pregnancies.

Serum levels of placental alkaline phosphatase (PLAP), human placental lactogen (HPL) and oestriol (E3) were investigated in 33 women with high-risk pregnancies. In pregnancies complicated by intrauterine growth retardation (IUGR) low PLAP values were constantly recorded. HPL values showed a similar pattern while E3 levels were between normal mean and the lower limit of -2 SD. A clear differentiation between IUGR and pre-eclampsia was achieved by the simultaneous determination of PLAP and HPL. It is suggested that PLAP determinations may be more informative than E3 to detect placental insufficiency.

Adult↗

PubMed1984

Tumor markers in colorectal carcinoma. An evaluation of carcinoembryonic antigen, tissue polypeptide antigen, placental alkaline phosphatase and pseudouridine.

The biologic markers carcinoembryonic antigen (CEA), tissue polypeptide antigen (TPA), placental alkaline phosphatase ( PLAP ) and pseudouridine were analysed in 37 patients with colorectal carcinoma. CEA, TPA and PLAP were derived from the serum and pseudouridine from the urine. The incidence of all four markers increased with advancing stages of the disease. Patients with distant metastases had elevated levels of CEA, TPA, PLAP and pseudouridine in 85, 27, 18 and 33 per cent of the total cases, respectively. When survival was compared, patients with 2 to 4 elevated markers had shorter survival than those with none or only one elevated marker.

Adolescent↗

PubMed1984