Search PubMed⌕ Search

Biomedical subjects

T Stigbrand

Publications and source records attributed to T Stigbrand.

At least 55 records · Page 3Linked to original sources
PubMed1996

Prognostic value of serum analyses of S-100 beta protein in malignant melanoma.

S-100 protein was first described in the central nervous system but is also present in malignant melanoma cells. Immunohistochemical detection of S-100 is widely used in the histopathological diagnosis of malignant melanoma. In the present study serum levels of S-100 beta protein were measured in 643 patients with cutaneous malignant melanoma. An immunoradiometric assay with three monoclonal antibodies against bovine S-100 protein beta subunit was used. At the time of blood sampling 553 patients were in clinical stage I, 24 in clinical stage II and 66 in clinical stage III. The overall survival rate was strongly associated with serum levels of S-100 protein. The observed/ expected death ratio was markedly increased with increasing levels of S-100 beta (P < 0.001). A fivefold increase in relative hazard was indicated by a value of S-100 beta exceeding 0.6 microgram/l (P < 0.001) and when this cut-off level was used S-100 beta had additional prognostic value independent of clinical stage (P < 0.001). Our data strongly suggest that S-100 beta in serum is an independent prognostic marker that may be useful in identifying high-risk cases and monitoring response to therapy in patients with malignant melanoma.

Adolescent↗
PubMed1996

Twenty years with monoclonal antibodies: State of the art--Where do we go?

In this review, we have selected some parameters with the potential to improve the efficacy of RIL and RIT. Focus has partially been on the behaviour of radiolabelled antibodies in vivo in relation to properties and amounts of both target antigen and the antibodies used. If, out of the 28 factors listed in Table 1, some should be given preference in future work, it is our opinion that after the initial saturation of the tumour site a rapid decrease in redundant antibody is of significant importance. Furthermore, quantitative aspects of both antigens and antibodies should be more carefully evaluated when possible. By combining several of the listed approaches toward increasing efficiency, a more extensive use of RIL and RIT could be expected in the future.

Antibodies, Monoclonal↗
PubMed1996

Secondary antibodies as tools to improve tumor to non tumor ratio at radioimmunolocalisation and radioimmunotherapy.

One way of selectively improving the efficiency of radioimmunolocalization and radioimmunotherapy is to eliminate redundant, circulating, non-targeting radiolabeled antibodies after saturation of the target sites. Secondary antibodies of different types have been proposed as clearing agents for such purposes. The conceptually different approaches of the 'secondary antibody' strategy including its advantages and limitations are discussed. This mini-review also presents a model describing the kinetics of the components (the antigen, the primary and secondary antibodies) and approaches required to improve the efficacy of both radioimmunolocalization and radioimmunotherapy.

Animals↗
PubMed1996

Hantavirus antigen detection using human serum immunoglobulin M as the capturing antibody in an enzyme-linked immunosorbent assay.

An enzyme-linked immunosorbent assay (ELISA) was developed to detect different hantavirus antigens in cell culture; i.e. Puumala (PUU), Hantaan (HTN), and Dobrava (DOB) viruses. The assay was based on binding human serum immunoglobulin M (IgM) antibodies to the solid phase by use of goat anti-IgM antibodies. The captured IgM antibodies were present in the acute phase serum from two patients: one infected in Sweden and the other in Bosnia. Antigens being bound to the solid phase by the human anti-PUU and anti-DOB/HTN IgM antibodies were detected by a broadly reacting polyclonal rabbit anti PUU-recombinant nucleocapsid protein antiserum. The IgM isotype was proven to be at least five times more efficient than IgG when used as the capturing antibody. The sensitivity of the PUU antigen ELISA was approximately 0.5 ng/ml, as measured by titration with a PUU recombinant nucleoprotein antigen. Cell-associated PUU antigen in tissue culture was seen after 48 hr by the PUU-ELISA and after 96 hr by immunofluorescent assay. When tested for capacity to discriminate between PUU, DOB, and HTN viruses, significant differences were found: the Swedish serum detected PUU antigen at high titers, whereas no reactivity was found against DOB and HTN; the Bosnian serum detected both DOB and HTN at high titers but had a low reactivity to PUU. The method was also tested for its usefulness in detecting PUU antigen in bank vole (clethrionomys glareolus) lungs. Of 59 animals captured from the surroundings of patients with nephropathia epidemica, three became positive with a high activity in the PUU-ELISA, but with low reactivity in the DOB/HTN-ELISA. It is concluded that a sensitive ELISA has been developed to detect different hantaviruses in cell culture and lungs of bank voles.

Animals↗
PubMed1996

Analyte and label binding assay read by flow cytometry.

A new immunometric two-site sandwich assay is introduced, in which a label-scavenging binding partner is added to the sample in addition to the analyte-binding partner. The scavenger binding partner binds excess label antibody, giving a signal proportional to the amount of excess label antibody in the sample solution. A set of two calibration curves is obtained from the two binding partners simultaneously, and a combination of the two signals gives an unambiguous determination of the analyte concentration, even for high analyte concentrations where the hook effect may occur. Two-particle immunofluorometric assays developed for placental alkaline phosphatase and human chorionic gonadotropin on the basis of this principle and yielding signals measured by flow cytometry gave rapid results (2 h) and had working ranges in excess of 5 and 6 orders of magnitude for the respective analytes.

Alkaline Phosphatase↗
PubMed1995

Use of anticytokeratin monoclonal anti-idiotypic antibodies to improve tumor:nontumor ratio in experimental radioimmunolocalization.

A syngeneic, high-affinity, anti-idiotypic monoclonal antibody (MAb; alpha TS1) raised against an anticytokeratin monoclonal antibody (TS1) was evaluated as a second antibody to promote the rapid clearance of radiolabeled TS1 from the blood during experimental radioimmunolocalization. By using a novel biosensor technology (BIAcore), association rate dissociation rate, and affinity constants between the idiotype and the anti-idiotype could be determined. The in vivo results in nude mice carrying HeLa Hep 2 tumors demonstrate the possibility of selectively regulating the amount of the idiotypic 125I-labeled circulating MAb by in vivo injection of this high-affinity, anti-idiotypic antibody. Injection of the anti-idiotype in a molar ratio of 0.75 to the idiotype cleared the blood pool from circulating radiolabeled idiotype within 24 h, with a concomitant rapid excretion of 125I in urine. The total amount of remaining radioactivity in the animals decreased to 15-20% during these 24 h, with the tumors still retaining 60-65% of their initial radioactivity. This approach, using syngeneic primary and secondary MAbs with minimized immunogenicity, significantly improves the tumor:nontumor ratio, thus improving efficiency in experimental radioimmunolocalization and radioimmunotherapy, leaving the endogenous antibody repertoire of the host unaffected.

Animals↗
PubMed1995

S-100 beta has a neuronal localisation in the rat hindbrain revealed by an antigen retrieval method.

The localisation of S-100 in mammalian CNS neurons has been under debate for more than two decades. We address the question with two polyclonal and two new monoclonal antibodies. The specificity and the distribution in rat brain is based on an antigen retrieval method. We present evidence that aldehyde fixatives mask S-100 beta in neurons, and that the immunoreactivity is retrieved after trypsinisation. Neuronal S-100 beta is also detected in unfixed and ethanol fixed sections. The neuronal immunoreactivity is partly solubilised from unfixed tissue sections with 2.5 mM EDTA and is completely extracted with 2.5 mM EDTA and 1% Triton X-100. Most of the glial S-100 beta is washed out from unfixed tissue sections with saline. S-100 beta has distinct distribution in neurons of the hindbrain, i.e., the brainstem and cerebellum, but is not observed in the forebrain. One of the monoclonal antibodies immunostained neither neurons nor glia when it had been absorbed with S-100 crosslinked to nitrocellulose membranes. The distribution of neuronal S-100 beta differed from that of other neuronal calcium binding proteins, such as calbindin and parvalbumin. It was confined mainly to cholinergic neurons of the hindbrain. The presence of S-100 beta in distinct neuronal populations may indicate neurotrophic effects of S-100 beta. The notion is supported by the capability of S-100 to cause neurite outgrowth in vitro.

Animals↗
PubMed1995

In vivo and in vitro interactions between idiotypic and antiidiotypic monoclonal antibodies against placental alkaline phosphatase.

A monoclonal antiidiotypic antibody alpha H7, was generated against a monoclonal antibody H7 with specificity towards placental alkaline phosphatase. The in vitro and in vivo effects of alpha H7 were investigated. The antiidiotypic antibody was found to generate stable complexes with the radiolabeled idiotypic antibody, visualized both in vivo and in vitro, as revealed by PAGE and autoradiography. Using biosensor technology (BIAcore, Pharmacia) the interactions were followed in real time and the association rate, dissociation rate, and affinity constants between the reactants were determined (KA H7/PLAP 6.7 x 10(9) M-1, KA H7/alpha H7 3.2 x 10(9) M-1). By in vivo injection of the antiidiotype, a rapid dose dependent clearance of circulating radiolabeled idiotypes was demonstrated and a decrease in total body radioactivity was recorded with a concomitant dramatic increase in non-protein-bound 125I excreted in the urine. It is concluded that idiotypic-antiidiotypic interactions offer advantages in the regulation of antibody levels in vivo.

Aged↗
PubMed1995

Identification of angiotensinogen and complement C3dg as novel proteins binding the proform of eosinophil major basic protein in human pregnancy serum and plasma.

In sera from pregnant women, pregnancy-associated plasma protein-A (PAPP-A) circulates as a disulfide-bound complex (approximately 474 kDa) with the proform of eosinophil major basic protein (proMBP) (Oxvig, C., Sand, O., Kristensen, T., Gleich, G. J., and Sottrup-Jensen, L. (1993) J. Biol. Chem. 268, 12243-12246). We have produced monoclonal antibodies (mAbs) against the PAPP-A.proMBP complex and established a radioimmunoassay utilizing a mAb recognizing the PAPP-A subunit. Surprisingly, serum levels of proMBP exceed those of PAPP-A four to 10-fold on a molar basis throughout pregnancy. This result prompted an investigation of the status of proMBP in pregnancy. Using a proMBP-specific mAb two novel proMBP complexes have been isolated by chromatographic techniques. Based on sequence analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and reaction with specific antibodies, one is shown to be a 2:2 disulfide-bound complex (approximately 200 kDa) between proMBP and angiotensinogen. The other is a 2:2:2 complex (approximately 300 kDa) between proMBP, angiotensinogen, and complement C3dg. Circulating proMBP in pregnancy is thus present in three types of complexes. These results suggest that specific interactions between the complexed proteins occur in pregnancy, and the possibility is raised that their interactions are important in the pathophysiology of pregnancies associated with hypertension.

Amino Acid Sequence↗
PubMed1995

Methanethiolation of the liberated cysteine residues of human alpha 2-macroglobulin treated with methylamine generates a derivative with similar functional characteristics as native alpha 2-macroglobulin.

The thiol-modifying reagent methyl methanethiosulfonate reacts with the cysteine residues of thiol esters released upon treatment of human alpha 2-macroglobulin with methylamine. This methanethiolation generates a derivative of alpha 2-macroglobulin, with an 'open trap' and slow mobility in non-denaturing PAGE, similar to native alpha 2-macroglobulin. This similarity is further substantiated by surface hydrophobicity determinations and by the fact that neither the derivative nor native alpha 2-macroglobulin are cleared from the circulation in mice. Cleavages of bait regions in the derivative and native alpha 2-macroglobulin, however, result in electrophoretically fast forms which are cleared from the circulation in mice. In contrast to native alpha 2-macroglobulin, which can bind 2 mol chymotrypsin/mol, alpha 2-macroglobulin treated with methylamine and methylmethanethiosulfonate binds only 0.8 mol chymotrypsin/mol. Protection of trypsin against inhibition by soybean trypsin inhibitor is significantly better when alpha 2-macroglobulin is modified by methylamine and methylmethanethiosulfonate than when it is modified by dinitrophenyl thiocyanate, which cyanylates the exposed thiol group. The methanethiolated derivative is also more stable than the corresponding cyanylated derivative in that it is transformed to an electrophoretically fast form with a half-life of 9 h as compared to a half-life of 7 h for the latter. The transformation to the fast form is not due to instability of the thiol modification.

Animals↗
PubMed1995

Syngeneic anti-idiotypic antibodies eliminate excess radiolabeled idiotypes at experimental radioimmunolocalization.

Significant improvements in tumor/nontumor ratio can be achieved by injections of nonlabeled anti-idiotypic monoclonal antibodies (MAbs) during radioimmunolocalization and radioimmunotherapy using MAbs to target experimental tumors. The in vivo effects of an anti-idiotypic MAb (alpha H7) against a radioiodinated, high affinity, low dissociation rate, monoclonal antiplacental alkaline phosphatase antibody (H7) was investigated. Following in vivo injection of the anti-idiotypic MAb, the radioactivity in experimental tumors was found to decrease only 25% while the reduction of corresponding radioactivity in nontumor tissues amounted to 65-85%, compared to the group receiving no anti-idiotypic MAbs. These results indicate that it is possible to partially clear the circulation and nontumor tissues from excess of radiolabeled idiotypic antibody, without significant decrease in specific tumor localization, increasing the tumor/nontumor ratio three- to fourfold. Circulating nontumor targeting radiolabeled antibodies is one of the major limiting factors in radioimmunotherapy today. Injection of anti-idiotypic MAbs could selectively significantly reduce the radiation dose to radio-sensitive tissues, i.e., bone marrow and intestine, thus improving efficiency in radioimmunoscintigraphy and radioimmunotherapy.

Animals↗
PubMed1995

Neutrophil alkaline phosphatase activity increase in bacterial infections is not associated with a general increase in secretory vesicle membrane components.

The content of alkaline phosphatase (ALP) was determined in neutrophils isolated from patients with acute bacterial infections by a standard enzyme assay. Compared with control cells, patient cells exhibited about a fivefold increase in ALP activity. There was no difference between the ALP Km values of control and patient cells, which indicates that the elevated activity in patient cells was due to the presence of increased amounts of the enzyme. The ALP isozyme in both cell types was determined to be the tissue-unspecific ALP. The fact that much of the ALP activity was measurable only in the presence of detergent suggested that the enzyme was localized in the secretory vesicles, a putative reservoir of plasma membrane components. The amount and subcellular distribution of two other secretory vesicle membrane proteins, i.e., cytochrome b and complement receptor 3, were not altered; hence, we conclude that there was no general increase in amounts of secretory vesicle membrane constituents in the patient cells.

Alkaline Phosphatase↗
PubMed1994

The alkaline phosphatase in human plexus chorioideus.

The content of alkaline phosphatase isozymes in various brain regions was determined by monoclonal immunocatalytic assays. The levels of the isozymes in human brain tissues were low compared with those in other human tissues, liver, kidney, bone, intestine and placenta. Plexus chorioideus in the brain, however, was found to express significant amounts of alkaline phosphatase activity. The purified isozyme from human plexus chorioideus demonstrated a single 70 kDa protein band on SDS-polyacrylamide gel which coincides with that of tissue-unspecific alkaline phosphatase from human liver. The isozyme expressed in the plexus was confirmed to be the tissue-unspecific alkaline phosphatase isozyme with regard to its reactivity with monoclonal antibodies specific for liver alkaline phosphatase, heat stability, and the inhibition by amino acids. This finding adds new dimensions to the functional role this isozyme may play.

Alkaline Phosphatase↗
PubMed1994

Expression of a heterodimeric (placental-intestinal) hybrid alkaline phosphatase in KB cells.

A hybrid heterodimeric alkaline phosphatase expressed in KB cells, consisting of placental and intestinal (fetal) subunits, was purified by use of two different immunoaffinity columns using the monoclonal antibodies 2HIMS-1 and HPMS-1. The closely related subunits were found to yield a dimeric active enzyme glycosylated as the mature heterodimeric forms. This enzyme displays intermediate properties to the placental and intestinal (fetal) isozymes with regard to heat stability, inhibition patterns with amino acids and amino acid derivatives, as well as reactivity with monoclonal antibodies specific for human alkaline phosphatase isozymes. Peptide fragments obtained from the hybrid enzyme after cyanogen bromide cleavage belong to either the placental or intestinal (meconial) isozyme as evaluated by SDS polyacrylamid gel electrophoresis, and the N-terminal amino acid sequences, corresponding to the placental and intestinal subunits, can be identified in the peptide fragments. By N-glycanase digestion or tunicamycin treatment, the molecular mass of the subunits was reduced to 62 kDa compared to 69 kDa for the native ones. The results confirm that some cell lines can synthesize hybrid alkaline phosphatases.

Alkaline Phosphatase↗
PubMed1994

Binding of lipoprotein lipase to alpha 2-macroglobulin.

The interaction between bovine lipoprotein lipase (bLPL) and human alpha 2-macroglobulin (alpha 2M) was studied by use of non-denaturing PAGE and gel-permeation, Zn(2+)-Sepharose and heparin-Sepharose chromatography. It was demonstrated that bLPL in vitro binds non-covalently to native alpha 2M, but not to the receptor-recognized form produced by treatment of alpha 2M with chymotrypsin or methylamine. A small amount of bLPL was bound covalently to alpha 2M by disulphide interchange, when incubated together with chymotrypsin or methylamine. Whereas alpha 2M in complex with bLPL still bound to Zn(2+)-Sepharose, bLPL lost the ability to bind to heparin-Sepharose. Preincubation of bLPL with heparin prevented complex-formation with alpha 2M, suggesting that alpha 2M interacts with the heparin-binding domain of bLPL. Experiments in which 125I-bLPL was incubated with human plasma at 20 degrees C demonstrated an 11-17% binding of the labelled lipase to alpha 2M, indicating that this interaction may be of physiological significance.

Animals↗