Biomedical subjects

B Landmeier

Publications and source records attributed to B Landmeier.

6 recordsLinked to original sources

PubMed2001

Solid-phase analysis method for (S)-[18F]fluorocarazolol and its metabolites.

(S)-[18F]Fluorocarazolol is a radiopharmaceutical developed to quantitatively assess beta-adrenergic receptors in vivo via positron emission tomography imaging. Since radioactive metabolites of (S)-[18F]fluorocarazolol rapidly appear in the plasma, methods for conveniently and reliably evaluating plasma for (S)-[18F]fluorocarazolol content are required. Here we present methods and validation of an approach using commercial extraction cartridges that is faster and more convenient than an approach using internal-surface reverse-phase chromatography but yields comparable results.

Adrenergic beta-Antagonists↗

PubMed1988

Membrane-associated interleukin 2 epitopes on the surface of human T lymphocytes.

Analysis of surface fluorescence with flow cytometry has revealed the presence of membrane-associated interleukin 2 (IL-2) epitopes on the surface of long term human T cell clones. These IL-2 epitopes could not be accounted for by soluble IL-2 binding to its specific receptor or adsorbing nonspecifically to the cells. The level of surface IL-2 antigenic determinants on the T cell clones was decreased in the presence of phorbol esters and increased in the absence of an exogenous source of IL-2. It was completely lost upon stimulation of the clones to produce the soluble lymphokine. Surface IL-2 epitopes were also detected on the Jurkat tumor cell line which secretes IL-2 upon stimulation and on another T cell tumor line MOLT 4. MLA-144 produces IL-2 constitutively; however, it did not possess membrane-associated epitopes. Tumor lines of other lineages were negative. A subpopulation of peripheral blood T lymphocytes demonstrated some membrane-bound IL-2, whereas non-T peripheral blood mononuclear cells were negative. Thus, cells with the potential of producing and secreting IL-2 upon stimulation possessed the surface epitopes of the lymphokine and cells either actively secreting IL-2 or without the potential for secretion were negative for surface expression. Membrane-associated IL-2 antigenic determinants appear to represent a T lymphocytic surface marker of potential cellular function. The relationship of this marker to the secreted lymphokine is not known. Although it is possible that the epitopes seen were present on a distinct molecule independent of secreted IL-2, the distribution on a variety of T cells and regulation via cellular activation suggest that the surface expression of IL-2 epitopes is in some way related to the soluble lymphokine.

Antibodies, Anti-Idiotypic↗

PubMed1987

Targeting of ganglioside GD2 monoclonal antibody to neuroblastoma.

The biodistribution of 3F8, and IgG3 murine monoclonal antibody (MoAb) specific for the disialoganglioside GD2, was studied in nude mice xenografted with human neuroblastoma (NB). 3F8 conjugated to radioactive iodine and injected intravenously localized selectively to seven human NB when compared with Ewing's sarcoma and Hela cell xenograft controls. Uptake in NB was shown to be specific for MoAb 3F8 when contrasted with pooled mouse IgG or irrelevant IgG3 MoAb controls. Both small (50 mg) and large tumors greater than 2 g) showed radiolocalization. The percent injected dose uptake per gram tumor ranged from 8 to 50% and was inversely correlated with tumor size. Optimal tumor to normal tissue ratios were reached by 24-48 hr. There was no abnormal uptake in the reticuloendothelial system and the MoAb did not cross the blood-brain barrier. Based on the kinetics of the amount of radioactivity deposited in tissues, the relative radiation dose to normal organs was estimated to be 1% to 20% of the tumor dose. The MoAb 3F8 is useful for targeting radioactivity to human NB in vivo and the nude mice xenograft model may allow optimization of parameters that influence such biodistribution.

Animals↗

PubMed1986

Complete tumor ablation with iodine 131-radiolabeled disialoganglioside GD2-specific monoclonal antibody against human neuroblastoma xenografted in nude mice.

The antibody 3F8, an IgG3 murine monoclonal antibody (MoAb) against disialoganglioside GD2, could target iodine-131 (131I) to established subcutaneous human neuroblastoma (NB) xenografts in BALB/c nude mice. 131I-radiolabeled MoAb (0.125-1 mCi) was injected iv. Tumor radioactivity over time was calculated from scintigraphy, and radiation dose to individual tumors was calculated. Tumor shrinkage occurred only with 131I-labeled 3F8, but not with nonradioactive 3F8 or radiolabeled irrelevant antibody. While the tumor of the control mice enlarged by tenfold, the treated tumor showed over 95% shrinkage by 12 days. Both the rate of shrinkage and duration of tumor response were dose dependent. Calculated doses of more than 10,000 rad could be achieved. Only those tumors that received more than 4,200 rad were completely ablated without recurrence. Recurrent tumors were not antigen negative or radioresistant. These results confirmed the prediction based on imaging studies that human NB xenografts could be effectively eradicated with the use of 131I-labeled MoAb 3F8 with tolerable toxicities.

Animals↗

PubMed1986

Diagnostic imaging of human neuroblastoma with radiolabeled antibody.

In a previous study, the authors showed that iodine-131 labeled monoclonal antibody (Mab 3F8) could be used to image human neuroblastoma xenografts in mice with excellent tumor-to-tissue ratios. In this study they report their experience with six patients scanned with radiolabeled 3F8. There was strong accumulation of the labeled antibody in viable tumor, but no significant uptake was noted in normal brain, liver, spleen, or adrenal glands. Tumor-to-nontumor activity ratios varied but were approximately 10:1-20:1. This ratio yields good contrast for visualization. Time-activity curves show that radioactivity levels in normal tissue have a half-time of about 40 hours, whereas tumor tissues show a half-time of about 60 hours. Significant gastric secretion of free iodine demonstrated that the Mab was being deiodinated. Calculated radiation doses indicate that tumors receive at least ten times the dose to other tissues. The results indicate that Mab 3F8 has clinical potential for both imaging and therapy of human neuroblastomas.

Adolescent↗

PubMed1985

Monoclonal antibodies to a glycolipid antigen on human neuroblastoma cells.

Using a somatic cell hybridization technique, four murine monoclonal antibodies (three immunoglobulin M and one immunoglobulin G3) were produced against a human neuroblastoma cell surface glycolipid antigen. They reacted strongly with all human neuroblastoma tumor-containing specimens and six of eight human neuroblastoma cell lines. More than 98% of each neuroblastoma cell population possessed this surface antigen, and in the presence of complement, 100% of them were killed. While melanoma and osteogenic sarcoma carried this antigen, leukemia and most Ewing's and Wilms' tumors did not. There was no cross-reaction with 30 normal or remission bone marrow samples and none with normal human tissues other than neurons in vitro. This antigen was neuraminidase sensitive, separable on thin-layer chromatogram, and did not modulate after combining with the monoclonal antibodies. These antibodies could detect less than 0.1% tumor cells deliberately seeded in the bone marrow samples. Because of their unique properties, these monoclonal antibodies may have diagnostic and therapeutic potentials.

Animals↗