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T Stigbrand

Publications and source records attributed to T Stigbrand.

At least 91 records · Page 5Linked to original sources
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↗
PubMed1992

In vivo measurement of the association constant of a radio-labelled monoclonal antibody in experimental immunotargeting.

Exploring the fundamental mechanisms behind the low tumour uptake of labelled monoclonal antibodies (MoAbs) during in vivo immunotargeting, experiments were performed to estimate the in vivo value of the association constant (Ka) in an experimental targeting reaction. An artificial tumour model was utilised, based on diffusion chambers (DC) filled with antigen-coated polymer particles, implanted i.p. in normal, immunocompetent mice (NMRI/BOM). The MoAb H7 with specificity for placental alkaline phosphatase (PLALP) was chosen for this experiment. Each mouse carried two DC, one target DC filled with PLALP-coated particles, and a second control DC with the same amount of uncoated particles. The DC contained escalating doses of particles, ranging from 0.1 mg to 16 mg per DC, with groups of 6-12 animals per dose level. The next day after the implantation, a constant dose of 125I-labelled Fab fragments of H7 was injected i.v. in each mouse. The association constant Ka as measured from the binding data obtained in vivo was not significantly different from the value measured in vitro when the same target DC were incubated with the 125I-Fab in test tubes. This indicates that in vivo impairment of the antibody avidity is not the reason why a relatively low tumour uptake is generally experienced in immunotargeting studies.

Alkaline Phosphatase↗
PubMed1992

CA125 and placental alkaline phosphatase as serum tumor markers in epithelial ovarian carcinoma.

Placental alkaline phosphatase (PLAP) was measured by an immunoradiometric assay using the monoclonal antibody C2 (PLAP-C2). Serum samples of 135 patients with epithelial ovarian cancer were analyzed, and the results were compared with CA125 levels. CA125 and PLAP-C2 were elevated in 85 and 43% of the patients, respectively. Only 1 patient with normal CA125 and evidence of disease at the time of sampling had an elevated PLAP-C2. Fifty-three patients with measurable tumor were followed longitudinally during chemotherapy. Correct correlation with disease evolution was observed in 95% of the patients for CA125 and in 59% for PLAP-C2. The PLAP-C2 assay did not add significantly to the predictive value of CA125 in the diagnosis and follow-up of epithelial ovarian cancer.

Alkaline Phosphatase↗
PubMed1992

Effects of growth hormone and estrogen on rat angiotensinogen quantified by an enzyme linked immunosorbent assay.

An enzyme linked immunosorbent assay for rat angiotensinogen was developed based on one monoclonal antibody with high affinity for angiotensinogen and des-angiotensin 1-angiotensinogen and rabbit polyclonal antibodies for angiotensinogen was developed. Serum levels of angiotensinogen were lower in female than in male rats but increased significantly after hypophysectomy. Estrogen substitution after hypophysectomy had no further stimulatory or inhibitory influence. In hypophysectomized animals continuous and intermittent growth hormone administration had clearly different effects. The results indicate that the sexually dimorphic secretion of growth hormone is involved in the regulation of circulating angiotensinogen concentrations in the rat.

Angiotensinogen↗
PubMed1992

Chemical nature of intestinal-type alkaline phosphatase in human kidney.

Approximately 10% of the alkaline phosphatase activity in human kidney is derived from the intestinal-type alkaline phosphatase isoform, which can be differentiated from adult intestinal alkaline phosphatase by selective reactivity with monoclonal antibodies. The NH2-terminal sequence of the renal intestinal-type alkaline phosphatase was shown to be identical to sequences of the adult and meconial alkaline phosphatases except for the NH2-terminal valine residue, which is missing in the renal intestinal-type enzyme. Incubation of purified meconial alkaline phosphatase with kidney homogenate resulted in removal of the NH2-terminal valine residue, indicating the presence of aminopeptidases in kidney that catalyze this hydrolysis. Furthermore, the oligosaccharide chains of the renal intestinal-type alkaline phosphatase were shown to differ from those of meconial and adult intestinal alkaline phosphatases, as revealed by lectin affinity chromatography. The heterogeneity of the intestinal-type alkaline phosphatase can therefore be generated both by partial peptide bond hydrolysis and differences in glycosylation.

Alkaline Phosphatase↗
PubMed1992

Placental alkaline phosphatase as the placental IgG receptor.

We review data from our studies of the physiological role of placental alkaline phosphatase (PLAP) and report that, in addition to functioning in catalysis, PLAP has the capacity to bind the Fc portion of human IgG. The dissociation constant for the interaction (3.86 mumol/L) indicates that the PLAP-IgG complex probably occurs in vivo. Furthermore, the electrophoretic and immunochemical properties of PLAP are identical to those of the purified placental Fc receptor. This receptor is believed to participate in the transfer of IgG molecules from the maternal circulation to the fetus during pregnancy. Studies with HEp2 cells show that PLAP is necessary for the internalization of IgG molecules. PLAP behaves, at least in this cell line, as an Fc receptor. The presence of large amounts of PLAP in clathrin-coated vesicles prepared from placenta strongly indicates that PLAP is involved in the endocytic machinery in this organ. We conclude that these results, taken together, suggest a novel biological role for PLAP.

Alkaline Phosphatase↗
PubMed1991

Serum levels of human alkaline phosphatase isozymes in relation to blood groups.

By use of sensitive immunocatalytic assays, based on isozyme specific monoclonal antibodies, the activities of the three main human alkaline phosphatases were determined in serum. The activities were related to ABO blood groups and secretor phenotypes. The activity of intestinal alkaline phosphatase was found to be strongly correlated with ABO blood groups and secretor phenotypes, while neither the placenta alkaline phosphatase activity nor the tissue unspecific alkaline phosphatase activity demonstrated any dependence on blood groups or secretor phenotypes. Non-secretors, independent of ABO blood groups, demonstrated low activities of intestinal alkaline phosphatase in serum, amounting to approximately 20% of the activities in the secretor groups. Within the secretor group, the lowest activities were observed for blood group A (2.8 +/- 1.1 IU/l; mean +/- SEM) and the highest for blood groups B and O (14.1 +/- 1.1 IU/l and 19.0 +/- 2.5 IU/l, respectively). These results confirm that the activities of intestinal alkaline phosphatase in serum have to be related both to ABO blood groups and to secretor phenotypes in order to be informative in clinical contexts.

ABO Blood-Group System↗
PubMed1991

Intracerebral distribution of Gp135, a new human brain glycoprotein.

The intracerebral distribution of Gp135, a new human membrane glycoprotein, defined by monoclonal antibodies, was determined by a quantitative enzyme-linked immunosorbent assay (ELISA) and the presence in different brain regions was shown by immunohistochemistry. The gray matter of frontal cortex and cerebellum were found to express this antigen in high amounts, whereas the subcortical white matter, pons and medulla oblongata displayed low levels. The presence of Gp135 was visualized in regions in which high density of neuronal dendrites and unmyelinated axons are found. Gp135 may participate in cell adhesion processes, in which cell-cell contacts and tissue integrity are fundamental.

Animals↗
PubMed1991

Isolation and characterization of a membrane glycoprotein from human brain with sequence similarities to cell adhesion proteins from chicken and mouse.

We previously described the production of monoclonal antibodies against a preparation of membrane glycoproteins from human brain [Berglund et al. (1987) J. Neurochem. 48, 809-815]. One of the glycoproteins, recognized by monoclonal antibody CF3, was specifically expressed in the brain. We now report the isolation and characterization of this glycoprotein, called glycoprotein 135 (Gp135). Gp135 was purified by means of lentil lectin affinity chromatography and immunoaffinity chromatography, using monoclonal antibody CF3, from a crude membrane extract of human brain cortex. Gp135 was shown to consist of a glycosylated single polypeptide chain with an apparent molecular mass of 135 kDa. The size of the polypeptide moiety was estimated to 115 kDa following N-glycanase digestion. The glycoprotein is anchored in the membrane by a glycosylphosphatidylinositol tail, as shown by phospholipase C digestion and liposome incorporation experiments. Amino acid sequence analysis of the amino terminal, and of an internal peptide obtained by V8 protease digestion of the glycoprotein, revealed a strong similarity to three previously described glycoproteins from chicken (contactin and F11) and mouse (F3) brains. These glycoproteins belong to the immunoglobulin superfamily and are implicated in cell adhesion phenomena in the developing brain. Gp135 may be the human counterpart to one or several of these glycoproteins.

Amino Acid Sequence↗
PubMed1991

Immobilized metal ion affinity partitioning, a method combining metal-protein interaction and partitioning of proteins in aqueous two-phase systems.

Immobilized metal ions were used for the affinity extraction of proteins in aqueous two-phase systems composed of polyethylene glycol (PEG) and dextran or PEG and salt. Soluble chelating polymers were prepared by covalent attachment of metal-chelating groups to PEG. The effect on the partitioning of proteins of such chelating PEG derivatives coordinated with different metal ions is demonstrated. The proteins studied were alpha 2-macroglobulin, tissue plasminogen activator, superoxide dismutase and monoclonal antibodies. The results indicate that immobilized metal ion affinity partitioning provides excellent potential for the extraction of proteins.

Antibodies, Monoclonal↗
PubMed1991

The effect of an N-methyl-D-aspartate lesion in the hippocampus on glial and neuronal marker proteins.

The study employed an immunochemical quantification of brain cell marker proteins in addition to quantitative morphology in order to provide a more multifacetted and characterized model for an excitotoxic CNS lesion. The importance of the approach in the evaluation of the potential of neuroprotective agents is emphasized. The S-100 protein, the glial fibrillary acidic (GFA) protein, neuron specific enolase (NSE) and neuronal intermediary filament polypeptides (NF 68 and NF 200) were measured with a dot-immunobinding assay, 3-30 days after a unilateral injection of N-methyl-D-aspartate (NMDA) in the left dorsal hippocampus of the rat. After 3 days, the neuronal cell loss averaged 80% in the hippocampus. The S-100 content was reduced 3 days after injection, but was 150% of control at 30 days. GFA increased constantly from days 3 to 30. The neuronal marker proteins were all markedly reduced 7 days after injection. However, at 30 days, NF 68 and NF 200 were close to control (80%). Increasing content would reflect regeneration and sprouting of neurites. The content of the neuronal cytoplasmic marker, NSE, was significantly lower than control also at 10 and 30 days, although a gradual recovery could be traced.

Animals↗
PubMed1991

Brain-associated glycoproteins expressed in bovine heart Purkinje fibres.

The Purkinje fibres of bovine heart were investigated immunohistochemically by use of monoclonal antibodies with specificity against the glycoproteins Thy-1 and Gp120, expressed in human brain. The existence and expression in bovine tissues (brain and thymus) of antigens displaying similar properties and immunochemical crossreactivity with monoclonal antibodies against the human antigens were confirmed. Both these antigens, as identified by use of anti Thy-1 and anti-Gp120 monoclonal antibodies were found to be associated with the membranes of the impulse conduction system. The presence of the antigens was seen in areas facing other conduction cells. No parts of the cells facing the basal membrane of the fibres were stained. The continuous staining between the cells was different from that of desmosome related proteins. These findings may have physiological and functional implications and are interesting in relation to recent evidences suggesting that the conduction tissue might be a derivative of the neural crest.

Animals↗
PubMed1991

Correlation between the human and porcine complement system: a small-angle scattering study of cross immunity and methylamine-induced conformational changes of porcine C3 and C4 proteins.

The porcine complement proteins C3 and C4 have been isolated and then characterized using small-angle scattering methods. Within the limits of experimental errors, the porcine proteins are virtually identical with the corresponding human proteins as measured in terms of mol. wt, Mr and radius of gyration, R,: Mr(C3) = 198,000, Mr(C4) = 207,000, and R(C3) = 4.4 nm, R(C4) = 4.5 nm. The C3 and C4 proteins from pigs show cross-immunity with monoclonal antibodies (mAbs) raised against human C3 and C4, respectively. Using the Fab fragments of these mAbs as markers, it is indicated that porcine C3 and C4 undergo a conformational change after reaction with methylamine. The relatively large increase in the radius of gyration observed, delta R = 1.0-1.2 nm, going from the Fab complexes to the Fab complexes of the methylamine derivatives, is similar to that observed for human C3 under similar conditions. This may indicate that methylamine cleaves a labile thiol ester bond supposed to be present within the porcine proteins and that the epitopes interacting with the Fab fragments are very similar to those of the human proteins. Porcine C3 also resembles the human analogue by forming dimers after being subjected to methylamine and dilute lauryl sulphate: Mr = 404,000 and R = 7.9 nm.

Animals↗
PubMed1991

Identification and characterization of alkaline phosphatase isozymes in human colorectal adenocarcinomas.

Using alkaline phosphatase isozyme-specific immunocatalytical assays, the content of isozymes was determined in normal mucosas and adenocarcinomas from human colon or rectum. Tumor levels of both the tissue (liver)-unspecific and the placental-like alkaline phosphatase (PLAP-like) were elevated compared to normal mucosas of the same patients. Such elevations have been reported previously, particularly in seminomas and ovarian tumors. In several tumors, moreover, the intestinal isozyme was expressed in lesser amounts than in the adjacent mucosa. The present results indicate that the activation of two of the phosphatase isozymes, including expression of the typical germ cell line phosphatase (the PLAP-like isozyme), may occur even in nongonadal tumors. This may reflect an induction pattern of phosphatase isozymes, with implications for malignant transformation also in other tumors.

Adenocarcinoma↗
PubMed1991

Radioimmunoscintigraphy of gynecologic tumors with 131I-labeled anti-PLAP monoclonal antibodies.

Radioimmunoscintigraphy (RIS) was performed in 20 patients with gynecologic tumors, 14 ovarian, 5 cervical, and one endometrial carcinoma. One murine monoclonal antibody (mab) against placental alkaline phosphatase (H7) was used after radiolabeling with 131I. The labeling procedure yielded antibodies with specific activity varying between 60 and 73 MBq/mg mab. Each patient received 57 to 100 MBq of the preparation. RIS was performed 7 to 35 days later. Patients with ovarian adenocarcinoma had an accumulation of activity on RIS at tumor sites (79%, 11/14) verified by ultrasonography, CT, and clinical examination. A low or absent accumulation of activity was seen in patients with cervical tumors. The patient with an endometrial adenocarcinoma was seen to have an activity accumulation at RIS corresponding to tumor sites determined by ultrasound and/or CT. It is concluded that RIS using monoclonal antibodies against placental alkaline phosphatase can provide information which will supplement that gained from other investigations of patients with ovarian adenocarcinomas.

Adult↗