Biomedical subjects

D D Bigner

Publications and source records attributed to D D Bigner.

At least 163 records · Page 9Linked to original sources

PubMed1991

Production and characterization of antipeptide antibodies against human O6-methylguanine-DNA methyltransferase.

Four synthetic peptides from the sequence of human O6-methylguanine-DNA methyltransferase (MGMT), three corresponding to different hydrophilic regions and one corresponding to the sequence containing the alkyl acceptor residue cysteine 145, were used to immunize rabbits. The antibody against Peptide III (residues 171-184) was highly specific, and MGMT protein could be detected on Western blots of soluble protein extracts containing as little as 1 fmol of active MGMT. Antibodies against all of the peptides were able to immunoprecipitate denatured MGMT, while only the antibody against Peptide III was able to react with active enzyme. The antibody against Peptide III did not cross-react with methyltransferase from mice. The use of synthetic peptides has led to the production of a highly sensitive, specific antibody that recognizes native and denatured human MGMT. This antibody should prove useful in studies involving the detection, purification, and characterization of this enzyme.

Amino Acid Sequence↗

PubMed1991

Glycolipids and glycosyltransferases in permanent cell lines established from human medulloblastomas.

Medulloblastoma biopsies are heterogenous and might contain normal brain tissue, which limits the usefulness of such tumor material for biochemical analyses. We have, therefore, examined the gangliosides and their metabolism using the medulloblastoma cell lines. Daoy and D341 Med, cultured both in vitro and as xenografts in nude mice. The ganglioside patterns in the Daoy showed a switch from a high GM2, 70% (mol% of total ganglioside sialic acid) and low lactoseries gangliosides (2%) content in monolayer cultures, to a high proportion of lactoseries gangliosides (50%) and virtually no GM2 (1%) in xenografts, but an increased proportion of other a-series gangliosides. The D341 Med showed a similar change regarding the lacto-series gangliosides from 1% in suspension culture to 10% in xenografts. The activity of five glycosyltransferases, GM3, GD3, GM2, GM1 and LA2 synthases, did not parallel the ganglioside patterns and could not account for the noted variations therein. In the Daoy cell line the LA2 synthase as well as the GM2 synthase activity was relatively high in both culture systems, despite the marked difference in the expression of GM2 and the lactoseries gangliosides. These results suggest that environmental factors play a crucial role for the in vivo activity of the glycosyltransferases.

Animals↗

PubMed1991

Structural and immunological comparison of indigenous human O6-methylguanine-DNA methyltransferase with that encoded by a cloned cDNA.

O6-Methylguanine-DNA methyltransferase, a ubiquitous and unusual DNA repair protein, eliminates mutagenic and cytotoxic O6-alkylguanine from DNA by transferring the alkyl group to one of its cysteine residues in a second-order suicide reaction. This 22-kDa protein was immunoaffinity-purified to homogeneity from cultured human lymphoblasts (CEM-CCRF line) and compared with the O6-methylguanine-DNA methyltransferase purified to homogeneity from Escherichia coli expressing a cloned human cDNA. The cellular and recombinant proteins were identical in size, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of intact molecules and their peptides. Immunoprobing of Western blots with three monoclonal antibodies specific for human cellular O6-methylguanine-DNA methyltransferase further indicated identity of the two proteins. The amino acid sequence of the cellular protein was experimentally determined for 87 out of a total of 207 residues and was found to be identical to that deduced from the cDNA sequence. A unique cysteine residue at position 145 was identified as the methyl acceptor site by autoradiographic analysis of peptides and sequence analysis of 3H-methylated O6-methylguanine-DNA methyltransferase. These observations establish that the cloned O6-methylguanine-DNA methyltransferase cDNA encodes the full-length O6-methylguanine-DNA methyltransferase polypeptide that is normally present in human cells. Moreover, the cellular protein does not appear to be significantly modified by posttranslational processes.

Amino Acid Sequence↗

PubMed1991

Medulloblastoma: tumor biological and clinical perspectives.

Medulloblastoma is the most common central nervous system malignancy of childhood, with approximately 350 new cases seen in the United States each year. Although the low incidence of this tumor, compared with adult neoplasms such as breast or colon carcinoma, has limited laboratory and clinical research, recent studies have greatly enhanced our understanding of the biology, phenotype, genotype, and therapy of medulloblastoma. Further efforts to integrate laboratory and clinical studies of this tumor may allow design of novel therapeutic approaches resulting in enhanced disease-free survival.

Animals↗

PubMed1991

Disialoganglioside GD2 in human neuroectodermal tumor cell lines and gliomas.

Monoclonal antibodies (mAbs) recognizing the disialoganglioside II3(NeuAc)2GgOse3Cer (GD2) were produced by immunizing mice with the GD2-expressing neuroblastoma cell line LAN-1 and a prefusion boost with purified GD2 coupled to Salmonella minnesota. Two IgM mAbs were isolated which demonstrated high levels of reactivity (binding ratios in excess of 100) with GD2 by solid-phase radioimmunoassay and positivity in high-performance thin-layer chromatography (HPTLC) immunostain; only one (DMAb-20) was subsequently shown by analysis with a panel of defined ganglioside species to be specific for the minimum epitope of GD2 GalNAc beta 1-4(NeuAc alpha 2-8-NeuAc alpha 2-3)Gal-, DMAb-20 was used to evaluate the expression of GD2 by malignant glioma and medulloblastoma cell lines using cell surface radioimmunoassay. indirect membrane immunofluorescence. HPTLC immunostain, and densitometric analysis of extracted gangliosides from selected cell lines. Sixteen of 20 (80%) malignant glioma and 5 of 5 medulloblastoma cell lines reacted with DMAb-20; in agreement with previous studies, 5 of 5 neuroblastoma and 2 of 3 melanoma cell lines also reacted with DMAb-20, GD2 was proportionally increased in the glioma and medulloblastoma cell lines relative to levels in normal brain, as determined by densitometric analysis. In a phenotypic survey of malignant glioma biopsies, tumor cells in 24 of 30 (80%) cases stained positively with DMAb-20. Reactive astrocytes, both within the adjacent to tumors, were frequently intensely stained. Among the morphological variants of glioblastoma examined, the most intense staining with DMAb-20 was observed in neoplastic gemistocytes, with the weakest or absent staining in small cell glioblastomas. As GD2 is a commonly expressed surface antigen of gliomas and medulloblastomas, expression of which is retained in tissue culture. DMAb-20 will be useful in determining the functional role of GD2 in cell-cell interaction, adhesion, and invasion, and in defining altered growth control mechanisms of central nervous system neoplasms in in vitro models.

Animals↗

PubMed1991

Melphalan-induced toxicity in nude mice following pretreatment with buthionine sulfoximine.

Melphalan-induced toxicity in nude mice following pretreatment with a regimen of L-buthionine sulfoximine (BSO), previously shown to enhance the activity of this alkylating agent against rhabdomyosarcoma and glioma xenografts, was examined. Mice were pretreated with i.p. BSO (2.5 mmol/kg x 7 doses at 12-h intervals plus concomitant availability of a 20-mM solution in the drinking water) or vehicle prior to a single i.p. injection of melphalan (35.65 mg/m2). As compared with control animals who received no BSO pretreatment, mice pretreated with BSO lost weight prior to therapy with melphalan (6.9% weight loss vs 0.3% weight gain; P less than 0.005) and showed a greater mean nadir weight loss after melphalan (3.8% vs. 2.1%; P = 0.049). Treatment with melphalan was associated with histologic evidence of reversible gastrointestinal toxicity, reversible myelosuppression, and histologic evidence of acute renal tubular necrosis, with no differences being observed between mice that had been pretreated with BSO and those that had been pretreated with vehicle. No evidence of cardiac, hepatic, or skeletal muscle toxicity was found in melphalan-treated animals. These results suggest that treatment of nude mice with melphalan following BSO-mediated depletion of glutathione does not result in enhanced organ toxicity despite an increase in the antineoplastic activity of this alkylating agent.

Animals↗

PubMed1991

Positive therapeutic interaction between thiopurines and alkylating drugs in human glioma xenografts.

We used human anaplastic glioma xenografts to evaluate the therapeutic efficacy of combinations of alkylating drugs, either 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), 1-(2-chloroethyl)-3-(2,5-dioxo-3-piperidyl)-1-nitrosourea (PCNU), or procarbazine, and thiopurines, either 6-mercaptopurine (6MP) or 6-thioguanine (6TG). Using growth delay as the endpoint in subcutaneous (s.c.) tumors and increased life span as the endpoint in intracranial (i.c.) tumors, we found that combinations of chloroethylnitrosoureas (CENUs) and thiopurines were significantly more active than either type of agent alone. In contrast, combinations of procarbazine and thiopurines were not significantly more active than procarbazine alone. The therapeutic potentiation of the CENU was greater when the latter was given on the 4th day of the thiopurine treatment cycle than when it was given on the 1st day. Characterization of the interaction between CENUs and thiopurines also revealed a supraadditive therapeutic response at higher BCNU doses in combination with 6TG. Interaction between the nitrosoureas and the thiopurines probably occurs in the guanine base of tumor DNA and has important therapeutic implications.

Alkylating Agents↗

PubMed1991

The origin of O6-methylguanine-DNA methyltransferase in Chinese hamster ovary cells transfected with human DNA.

Transfection of Chinese hamster ovary (CHO) cells with human DNA has been shown in several laboratories to produce clones which stably express the DNA-repair protein, O6-methylguanine-DNA methyltransferase (MGMT), that is lacking in the parent cell lines (Mex- phenotype). We have investigated the genetic origin of the MGMT in a number of such MGMT-positive (Mex+) clones by using human MGMT cDNA and anti-human MGMT antibodies as probes. None of the five independently isolated Mex+ lines has human MGMT gene sequences. Immunoblot analysis confirmed the absence of the human protein in the extracts of these cells. The MGMT mRNA in the lines that express low levels of MGMT (0.6-1.4 x 10(4) molecules/cell) is of the same size (1.1 kb) as that present in hamster liver. One cell line, GC-1, with a much higher level of MGMT (4 x 10(4) molecules/cell) has two MGMT mRNAs, a major species of 1.3 kb and a minor species of 1.8 kb. It has also two MGMT polypeptides (32 and 28 kDa), both of which are larger than the 25 kDa MGMT present in hamster liver and other Mex+ transfectants. These results indicate that the MGMT in all Mex+ CHO cell clones is encoded by the endogenous gene. While spontaneous activation of the MGMT gene cannot be ruled out in the Mex+ cell clones, the intervention of human DNA sequences may be responsible for activation of the endogenous gene in the GC-1 line.

Animals↗

PubMed1991

Expression of O6-methylguanine-DNA methyltransferase in malignant human glioma cell lines.

When animals are treated with carcinogenic agents that alkylate O6-guanine residues, the incidence of tumors in specific tissues often relates inversely to the level of the DNA repair enzyme O6-methylguanine-DNA methyltransferase (MGMT) present in the tissue. Similarly, the hypersensitivity to anticancer chloroethylnitrosoureas of some human tumor cell lines is believed to result from their deficiency in MGMT. We have undertaken a comprehensive investigation of MGMT expression in a panel of nine characterized human glioma cell lines. Methyltransferase activity determined by incubating protein extracts of these glioma lines with [3H]methylated DNA ranged from undetectable in six lines (the Mer- phenotype) to greater than 0.8 pmol/mg in two lines (U-373 MG and D-392 MG). MGMT protein was undetectable in Western blots of the Mer- cell extracts probed with specific anti-MGMT monoclonal antibodies. Consistent with these results, steady-state levels of MGMT mRNA, determined by Northern blot analysis, were detectable only in the three Mer+ glioma lines (U-373 MG, D-392 MG, D-263 MG). Southern analysis of EcoRI-digested DNA probed with MGMT cDNA revealed no amplification, rearrangement or deletions of the MGMT gene in any of the glioma cell lines. This is the first report that examines MGMT expression at the biochemical, molecular and genetic levels in a particular tumor type. These studies suggest that transcriptional regulation is the basis of the Mer- phenotype in these malignant human glioma cell lines, since no gross structural or quantitative abnormalities of the MGMT gene were seen in the phenotypically Mer- lines.

Blotting, Northern↗

PubMed1991

Occurrence of lacto series gangliosides 3'-isoLM1 and 3',6'-isoLD1 in human gliomas in vitro and in vivo.

Monoclonal antibodies (MAb; DMAb, monoclonal antibodies derived at Duke Medical Center) directed against the oncofetally expressed lactotetraosyl gangliosides 3'-isoLM1 (IV3NeuAc-LcOse4Cer) and 3',6'-isoLD1 (IV3NeuAc,III6NeuAc-LcOse4Cer) were produced and their reactivity spectra compared to that of the alpha-3'-isoLM1 MAb SL-50. The IgM MAb SL-50 defines the epitope NeuAc (or NeuGc)alpha 2-3Gal beta 1-3GlcNAc, the terminal sequence of both gangliosides. SL-50 requires an unsubstituted GlcNAc residue; IgM DMAb-14 will accept the alpha 2-6 linked sialic acid to GlcNAc found in 3',6'-isoLD1. Immunohistochemical localization of 3'-isoLM1 was performed on 31 biopsy specimens of human gliomas; 15 (48%) expressed 3'-isoLM1 as defined by binding of MAb SL-50. Staining of small anaplastic cells, giant cells, and the glial component of gliosarcomas was observed. Neoplastic gemistocytes, when present, showed particularly intense staining. The 3'-isoLM1 and 3',6'-isoLD1 distribution in cultured cell lines and derived xenografts of primary tumors of the human central nervous system and of embryonal or neuroectodermal tumor derivation was determined. Six of 29 cell lines expressed 3'-isoLM1: 2/16 gliomas, 3/3 teratomas, 1/1 pancreatic adenocarcinoma. No cell line expressed detectable 3',6'-isoLD1 by immunostain analysis of ganglioside extracts. The 3'-iso-LM1-positive cell lines expressed it in xenograft form; in five xenografts, the corresponding cell lines of which were 3'-isoLM1-negative, it was a proportion of the monosialoganglioside fraction. 3',6'-isoLD1 was detected in two xenografts, D-54 MG (glioma) and PA-1 (teratoma). The demonstration of 3'-isoLM1 in gliomas in in vivo forms and the relatively infrequent expression by derived cultured cells suggest that ganglioside expression is modified by environmental forces. Expression of 3'-isoLM1 and 3',6'-isoLD1 in fetal and neonatal brain, in intense reactive astrocytosis such as polyunsaturated fatty acid lipidosis, and in primary neoplasms of the central nervous system suggests their role in cell-cell attachment during development, migration, and neoplastic transformation.

Animals↗

PubMed1991

Medulloblastoma cell-substrate interaction in vitro.

Medulloblastoma, a highly malignant pediatric tumor of the posterior fossa, demonstrates a marked propensity for leptomeningeal dissemination. Although the predominant site of relapse is the posterior fossa, the prevention of subarachnoid spread would be of significant therapeutic value. The established medulloblastoma cell lines D283 Med, D341 Med, D384 Med, D425 Med, D458 Med and Daoy have been investigated in in vitro adhesion assays for their capacity to bind to the predominant components of the leptomeningeal extracellular matrix: fibronectin, laminin and collagen IV. Growth on the reconstituted basement membrane matrix, Matrigel, was also assayed. Of the five neuronal phenotype DMed lines, all of which grow spontaneously as macrospheroids in standard fetal calf serum-containing tissue culture medium, only D425 Med and its sibline, D458 Med, derived from a subsequent sample from the same patient, displayed adherence to any of the substrata: approximately 20% of input D425 Med cells attached and exhibited cell spread and some extension (adhesion) on fibronectin. All other DMed lines failed to attach to these substrates. The glial phenotype cell line Daoy, which grows as an adherent monolayer under normal culture conditions, exhibited attachment, extension and growth on all substrata as did the glioma cell line U-251 MG and the neuroblastoma cell line SK-N-SH. The lack of attachment, and thus spread on components of the leptomeningeal extracellular matrix under in vitro assay conditions by 5/6 of the medulloblastoma cell lines investigated, is characteristic of neuronally differentiated cells, thus reinforcing the previously described neuronal phenotype of these lines. The readily demonstrated expression of N-CAM and L1 by all of the medulloblastoma cell lines suggests that the primary mode of leptomeningeal extension in vivo may be dependent on such other cell-cell and cell-substrate binding mechanisms.

Cell Adhesion↗

PubMed1991

Differentiation characteristics of newly established medulloblastoma cell lines (D384 Med, D425 Med, and D458 Med) and their transplantable xenografts.

Three new human medulloblastoma (MB) cell lines (D384 Med, D425 Med, and D458 Med) and their transplantable xenografts were examined for antigenic expression with antibodies against neuroectodermal antigens, cytoskeletal proteins, neuroendocrine markers, glioma-associated antigens, tenascin, human lymphocyte antigen molecules, epidermal growth factor receptor, and T-cell antigen by indirect immunofluorescence, avidin-biotin complex peroxidase immunohistochemistry, and immunoblot methods. We found that each of the three cell lines expressed vimentin; low-, middle-, and high-molecular-weight neurofilament proteins; and the synaptic vesicle membrane glycoprotein synaptophysin. Each of the cell lines also reacted with antibodies against neural cell adhesion molecules, but none of them were positive for antibodies against glial fibrillary acidic protein, keratin, microtubule-associated protein tau and microtubule-associated protein 2, human lymphocyte antigen-DR, epidermal growth factor receptor, and T-cell antigen. Immunoreactivities with anti-tenascin and anti-glioma-associated antibodies were variable in these cell lines. Anti-human lymphocyte antigen-A,B and anti-beta 2-microglobulin antibodies reacted with xenografts of D384 Med and D425 Med and were weakly positive for a small population of D384 Med cultured cells. In summary, the detection of neurofilament proteins and synaptophysin and the absence of glial fibrillary acidic protein provide strong evidence for a neuronal phenotype of D384 Med, D425 Med, and D458 Med.

Antigens, Neoplasm↗

PubMed1991

Therapeutic analysis of in vitro and in vivo brain tumor models.

Virtually all brain tumor models studied to date have demonstrated the activity of the nitrosoureas, an observation confirmed in a cohort of adult patients with high-grade gliomas. However, studies with animal brain tumor models have not led to the selection of other clinically active agents (with the possible exception of AZQ), leading investigators to conduct experiments with human CNS tumor-derived cell lines and xenografts. These studies have identified agents subsequently shown to be active in phase II clinical trials against high-grade glioma and medulloblastoma. Clinical phase III trials in progress will demonstrate if these agents result in increased disease-free survival, which is the ultimate goal of all preclinical therapeutic studies. Future research with these laboratory models may ultimately allow the definition of the mechanisms of drug resistance and the identification of modulations effective in bypassing or reversing this resistance.

Animals↗

PubMed1990

Characterization of the epidermal growth factor receptor in human glioma cell lines and xenografts.

Both permanent cultured cell lines and athymic mouse xenografts were established from two human glioblastomas. Biopsies from D-245 MG and D-270 MG contained amplified and rearranged epidermal growth factor receptor (EGFR) genes. Although the gene amplification and rearrangement seen originally was maintained in the xenografts, cultured cell lines established from these biopsies lost the amplified rearranged genes in vitro. Analysis of these cell lines and 11 additional permanent human glioma cell lines with normal EGFR gene copy number showed from 2.7 x 10(3) to 4.1 x 10(5) high affinity EGFRs/cell by radioreceptor assay. The RNase A protection assay showed minimal differences in the quantity of EGFR mRNA among the 13 glioma lines, while the D-245 MG and D-270 MG xenografts expressed approximately 10-20 times as much EGFR mRNA as the corresponding cell lines. Immunoprecipitation of EGFR from these lines, including D-245 MG and D-270 MG, demonstrated only the intact Mr 170,000 Da form, while truncated Mr 145,000 Da and 100,000 Da EGFR proteins were immunoprecipitated from the D-270 MG and D-245 MG xenografts, respectively. These studies demonstrate that gliomas with amplification of the EGFR gene are capable of establishing in culture but that the amplified rearranged genes are not maintained. Possible explanations are that the abnormal genes are lost during serial passage or that the cells with amplified rearranged genes only represent a minor subpopulation of cells, which are unable to grow in culture. In either case, these observations suggest that high expression and structural abnormalities of EGFR proteins generated by amplification and rearrangement of the EGFR gene provide a growth advantage for gliomas in vivo but not in vitro.

Adult↗

PubMed1990

Effect of epidermal growth factor on glioma cell growth, migration, and invasion in vitro.

Effects of epidermal growth factor (EGF) and an antibody (Ab-528) reactive against the binding site for EGF on human EGF receptors were studied on multicellular tumor spheroids obtained from three human glioma cell lines with high (D-37 MG), medium (D-247 MG), and low (D-263 MG) levels of EGF receptor expression. The D-247 MG and D-263 MG spheroids grew slowly or not at all in the absence of EGF, while in the presence of EGF they were growth stimulated. Tumor cell migration, as measured by the spread of cells from spheroids on a plastic substratum, was increased by the addition of EGF for all three cell lines. Stimulation of migration could be blocked by a subsequent addition of Ab-528 to the medium at a concentration of 50 micrograms/ml. Invasiveness of glioma cell spheroids into fetal rat brain aggregates was related to EGF receptor expression; the two lines with medium to high receptor expression (D-247 MG and D-37 MG) were invasive, while the line with low EGF receptor expression (D-263 MG) was noninvasive, as assessed by an in vitro coculture assay. In the D-247 MG cell line, morphometry revealed EGF-enhanced invasiveness of the tumor cells. The addition of the Ab-528 to EGF-treated cocultures reduced invasion in both D-247 MG and D-37 MG cell lines. Antibody Ab-528 alone did not affect glioma cell growth or migration but did inhibit invasiveness. The present study suggests that, in brain tumors with an increased number of normal-sized Mr 170,000 EGF receptors, EGF or an EGF-like ligand such as transforming growth factor-alpha may selectively facilitate expansive tumor growth and tumor cell invasion. This effect may in part be blocked or retarded by specific antibodies to the EGF receptor.

Cell Division↗

PubMed1990

Gangliosides in the human glioma cell line U-118 MG grown in culture or as xenografts in nude rats.

This study was undertaken to characterize gangliosides in the human glioma cell line U-118 MG. The cell line was grown both in cell culture and as xenografts in nude rats. A common finding in both culture and xenograft cells was the high proportion of the lactoseries ganglioside 3'-LM1, approximately one third of the total ganglioside sialic acid. Otherwise, there were marked differences between the two cell sources. The cells grown in culture had a more simple ganglioside pattern than those grown in xenografts. In the latter instance, more complex gangliosides of the lactoseries, including 3'8'-LD1, sialyllactonorhexaosylceramide and a branched structure with two terminal NeuAc alpha 2-3Gal beta 1- 4GlcNAc chains, and the gangliotetraose series were found. Another marked difference involved GM2, which in the cultured cells was a major fraction, indicating that the synthesis of the gangliotetraose series gangliosides in the former stopped at the level of GM2. These results show that the ganglioside composition of a glioma cell line is strongly influenced by environmental factors.

Animals↗

PubMed1990

Cytogenetics of human brain tumors.

The most frequent cytogenetic alterations in primary brain tumors are losses of chromosomes or chromosomal regions and the presence of double minute chromosomes (dmins). The regions which are lost and the genes which are amplified are distinctive for individual tumor types. Most malignant gliomas contain gains of chromosome 7 and losses of chromosome 10; losses of chromosome 22, 9p, and the sex chromosomes occur in subgroups of cases. The gene most frequently amplified in tumors with dmins is the epidermal growth factor receptor gene. Medulloblastomas have losses of 17p and most cases with dmins have c-myc gene amplification. Meningiomas have losses or deletions of chromosome 22. Identification of these specific cytogenetic abnormalities in human brain tumors has provided the framework for identifying genes which are amplified in them and has identified chromosomal regions likely to contain tumor suppressor genes, the loss or inactivation of which is important in the development of these tumors.

Brain Neoplasms↗

PubMed1990

Monoclonal antibody and F(ab')2 fragment delivery to tumor in patients with glioma: comparison of intracarotid and intravenous administration.

Non-i.v. delivery of radiolabeled monoclonal antibodies (MAbs) has been shown to increase tumor uptake and decrease dose to normal tissues. In this study, we have examined the potential advantage of intracarotid (i.c.) versus i.v. administration for the delivery of an intact MAb and a F(ab')2 fragment to tumor in patients with gliomas. Three patients received 10-50 mg of 81C6 IgG2b, a MAb reactive with the glioma-associated extracellular matrix antigen tenascin, and three received 5-20 mg of the F(ab')2 fragment of Mel-14, which is reactive with gliomas and melanomas. Paired-injection protocols, in which one-half of the MAb was labeled with 131I and administered by i.c. injection, and one-half was labeled with 125I and simultaneously administered by i.v. injection, were used. For both 81C6 IgG2b and Mel-14 (Fab')2, no differences in blood clearance half-times or urinary excretion rates of radioiodine were observed between i.c.- and i.v.-administered activity. Analysis of biopsy samples revealed i.c.:i.v. uptake ratios of 1.02 +/- 0.04, 0.95 +/- 0.03, and 1.03 +/- 0.05 for the accumulation of 81C6 IgG2b in temporalis muscle, normal brain, and glioma, respectively. Similarly, the i.c.:i.v. uptake ratios for Mel-14 F(ab')2 in these tissues were 0.98 +/- 0.04 (SD), 1.00 +/- 0.05, and 1.04 +/- 0.05. When the differences in percentage of injected dose/g uptake after i.c. and i.v. administration were compared, no statistically significant advantage for i.c. delivery was seen (P = 0.22-0.61). These data indicate that i.c. administration of MAb 81C6 IgG2b and Mel-14 F(ab')2 fragments offers no delivery advantage to offset the small but finite risk involved in cannulation and injection of the internal carotid artery.

Antibodies, Monoclonal↗