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Biomedical subjects

B P Avner

Publications and source records attributed to B P Avner.

At least 19 recordsLinked to original sources
PubMed1993

Application of the adenosine triphosphate-cell viability assay in human breast cancer chemosensitivity testing: a report on the first results.

Chemosensitivity testing in vitro of breast cancer has been difficult because of small tumour volume, an even smaller yield of viable cells after disaggregation, and the low evaluability rate and sensitivity of current assays. We have employed an alternative approach that quantitates intracellular adenosine triphosphate (ATP) as a measure of cell viability. This ATP-cell viability assay (ATP-CVA) determines in vitro tumor cell viability after exposure to chemotherapeutic agents in comparison to untreated controls following 6 days of incubation. Sixty-one fresh breast cancer specimens upon testing yielded an evaluability rate of 95%. Forty-seven of the tumors were untreated primary breast cancers, the remaining 14 were from patients with metastatic disease. Correlations of in vitro drug sensitivity with in vivo response were obtained for 17 treatment regimens in 14 patients with metastatic breast cancer. The level of sensitivity was 90% and the specificity 86%. These preliminary data demonstrated the ATP-CVA to be a practical in vitro approach to breast cancer testing. It will require a larger clinical study for confirmation.

Adenosine Triphosphate↗
PubMed1991

Evaluation and clinical relevance of patient immune responses to intravenous therapy with murine monoclonal antibodies conjugated to adriamycin.

A retrospective study was performed in order to examine the clinical relevance of human anti-murine antibodies (HAMA) to concurrent clinical events in 21 patients receiving intravenous therapy with cocktails of murine monoclonal antibodies conjugated to Adriamycin. In vivo tumor localization of the murine antibodies was also evaluated. Serum levels of HAMA, human-murine immune complexes (HMIC), and murine antibodies were measured using an automated fluorescence immunoassay. Immunohistochemical staining was performed on frozen sections of tumor biopsies from eight of the patients to examine the in vivo binding of the murine antibodies. The patients were divided into low, intermediate, and high antibody dose groups. The incidence of allergic symptoms (80%) and HAMA correlation (75%) were highest in the low dose group. Specific IgM HAMA was the most highly correlated with allergic reactions, being present in 61.5% of the allergic patients. Thirteen of the 21 patients studied (61.9%) developed allergic symptoms after one or more doses of the murine monoclonal antibody conjugates. The percentages of total antibody doses in the patients' sera at varying intervals post-infusion varied widely from patient to patient for any given time point and dose, suggesting complex factors in the distribution and clearance of the murine antibodies. All eight of the patients biopsied during or post-therapy exhibited tumor localization of the murine monoclonal antibodies. Six of the eight had concurrent HAMA in their sera. Thus, the presence of HAMA did not prevent in vivo localization of the murine antibodies in the target tumors.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Immunohistochemical phenotyping of human solid tumors with monoclonal antibodies in devising biotherapeutic strategies.

A panel of 14 monoclonal antibodies (MoAbs) (4 raised against breast cancer, 6 against colon cancer and 4 against melanoma) were used to phenotype frozen sections of tumor biopsies obtained from 110 patients, by avidin-biotin-peroxidase complex techniques. We observed heterogeneity of antigen expression among the multiple metastatic lesions of single patients, as well as among tumor lesions from different patients with similar tumor histotypes. A wide range of cross-reactivity of anti-(breast-carcinoma) and anti-(colon-carcinoma) MoAbs with other carcinoma histotypes and limited reactivity with melanoma and sarcoma was detected. Some of our anti-melanoma MoAbs were also found to cross-react with selected carcinomas. Nine of the 14 MoAbs most reactive with carcinomas of diverse histotypes have been identified. A mixture or 'cocktail' of different MoAbs could be selected for each individual patient in order to achieve binding of MoAbs with most, if not 100% of tumor cells. This study illustrates the approach that we have taken to individualize the cocktail of MoAbs for the development of patient-specific therapeutic immunoconjugates.

Adult↗
PubMed1989

Immunoconjugates of doxorubicin and murine antihuman breast carcinoma monoclonal antibodies prepared via an N-hydroxysuccinimide active ester intermediate of cis-aconityl-doxorubicin: preparation and in vitro cytotoxicity.

Doxorubicin (DXR) conjugated to murine monoclonal antibodies (MoAb) raised against human breast tumor cells demonstrated a MoAb-specific, molar ratio-dependent in vitro cytotoxicity. These conjugates were prepared on a scale sufficient to allow for subsequent clinical trials (1 to 3 g of MoAb per conjugation reaction). The conjugation reaction proceeded via an N-hydroxysuccinimide (NHS) active ester intermediate of cis-aconityl-DXR (CA-DXR), resulting in a cis-aconitate acid-sensitive linker between the DXR and MoAb. Molar ratios of DXR to MoAb ranged from 40 to 45. The immunoreactivity of conjugated MoAb was only slightly decreased from naked MoAb. When immunoconjugates were incubated with MoAb-reactive tumor cells for 3 hours, specific cell-killing was observed. If the exposure time was lengthened to 18 hours, however, nonspecific killing resulted. Incubation of the immunoconjugate with the nonspecific adsorbant Amberlite XAD-2 caused an average 30% decrease in the DXR-to-MoAb molar ratio, suggesting a population of drug that is tightly but noncovalently associated with MoAb.

Adsorption↗
PubMed1989

Therapeutic murine monoclonal antibodies developed for individual cancer patients.

The purpose of this work was to create antibodies that are highly specific to epitopes on the surface of patient tumor cells that, when added together as a "cocktail," bind to greater than 99% of the patient's tumor cells. We describe the rationale and the methods used to develop new murine hybridomas that secrete monoclonal antibodies reactive with surface markers expressed on breast, lung, colon, kidney, islet cell, and miscellaneous carcinomas and melanoma. A rapid immunofluorescence method (cell concentration fluorescence immunoassay) is also described that has been developed to rapidly screen culture supernatants on viable patient tumor cells, tumor cell lines, or peripheral blood cells. We report the development of one breast, five colon, and three melanoma, three nephroma, and two pancreatic islet cell carcinoma antibodies. The breast antibody binds to 75% of the breast tumors tested thus far and to the same percentage of colon tumors as do the five colon antibodies, 77-85%. The melanoma antibodies described react with 90-100% of the melanoma and prostate cancers tested. The total process of creating the hybridomas and screening the antibodies for potential clinical usefulness has taken from 6 to 9 months to complete, including testing normal tissue reactivity by immunohistochemistry and production of gram quantities of monoclonal antibodies from ascites.

Animals↗
PubMed1988

Characterization of a method using viable human target cells as the solid phase in a cell concentration fluorescence immunoassay (CCFIA) for screening of monoclonal antibodies and hybridoma supernatants.

A new method has been characterized for the use of viable target cells as the solid phase for screening of hybridoma supernatants in a cell concentration fluorescence immunoassay (CCFIA). Briefly, the specific target antigen on the cells is bound by the monoclonal antibodies and revealed by use of a fluoresceinated second antibody. Separation of free from bound antibody is accomplished by filtration in the 0.2 micron filter-bottom wells of specialized assay plates. Processing is automated in a Pandex screen machine, resulting in numerical fluorescence values for each well. This method is rapid (under 1 h per 96-well plate), highly sensitive (down to 0.2 ng/ml) and sparing of target cells (0.3-2.5 X 10(4) cells per assay well). It has been applied to 37 different varieties of human solid tumor cells, as well as to human peripheral blood mononuclear cells. The cells used as targets for the characterization of this method were still capable of attachment and growth when recovered post-assay. This method was compared with a viable cell enzyme-linked immunosorbent assay (ELISA) method, showing similar sensitivity and greatly shortened assay time. Comparison of the results from this method with those obtained from flow cytometric analysis performed on viable cells showed close correlation, whereas a lower correlation was seen with immunohistochemical methods using acetone-fixed cells. Development of this method made it possible to rapidly screen many thousands of hybridoma supernatants and successfully select those which were specific for surface antigens on viable cells.

Adenocarcinoma↗
PubMed1981

A method for culturing canine tracheal smooth muscle cells in vitro: morphologic and pharmacologic observations.

A method of culturing canine tracheal smooth muscle cells in vitro is described. The morphology of these cells is monitored up to 60 days in culture and selected stages are illustrated. The characteristics of these cells are numerous mechanical attachments, the presence of thick filaments in suitably processed cells, and their contractile response to in vitro administration of carbachol, a cholinomimetic drug. They also possess nexus formations and both thin (actin) filaments and 10-nm filaments. Mitosis is found in the nonconfluent preparations up to 16 days after culturing. Cultures of 2 to 8 days appear to be most useful as pharmacological test vehicles. This system will be used to explore the phenomenon of adrenergic beta-2 receptor desensitization in airway smooth muscle, to attempt to localize these receptor sites and to determine how receptor affinity and/or number may be regulating cell response to pharmacologic agents.

Animals↗
PubMed1981

Structure and function of the murine muscle-tendon junction.

The muscle-tendon junctions of the extensor carpi radialis longus and brevis muscles from adult Balb C Bailey/J mice have been examined tensiometrically and ultrastructurally following removal of cellular membrane and soluble cytoplasm by exposure to nonionic detergent. As judged by the ability of the extracted muscle to generate tension upon exposure to ATP and to transmit the generated tension to the tendon, detergent extraction leaves the muscle-tendon junction functionally intact. Electron microscopic analysis of the extracted muscle-tendon junctions reveals that the relationship between the terminal myofilaments and the lamina densa of the basal lamina is retained, despite the extensive extraction of the plasma membrane. Fine filaments (2-7 nm) are seen to connect the lamina densa with an electron-dense intracellular layer into which terminal actin filaments appear to insert. These fine filaments are considered to represent an important component of the structural linkage between myofilaments and connective tissue and hence to be a significant component of the tension transmitting mechanism. Their precise nature is not known, but some part of the filaments must pass through the hydrophobic compartment of the plasma membrane and thus must be a transmembrane component of considerable tensile strength. These studies suggest that detergent-extractable membrane lipids play no significant role in the transmission of tension at the muscle-tendon junction, and that fine filaments, probably protein, are responsible for transmitting tension from myofilaments, through the plasma membrane, to the lamina densa of the basal lamina.

Animals↗
PubMed1980

Effects of prostacyclin (PGI2) and indomethacin on neonatal lamb mesenteric and renal artery responses to electrical stimulation and norepinephrine.

The effects of prostacyclin (PGI2) and indomethacin on isolated neonatal lamb mesenteric and renal artery responses to electrical stimulation and injected norepinephrine were investigated. PGI2 (1 micro M) decreased baseline tension and significantly reduced vasoconstrictor responses to electrical stimulation and norepinephrine. Indomethacin raised baseline tension and potentiated the constrictor responses. PGI2 reversed completely the potentiating effects of indomethacin. These results suggest that PGI2 may modulate the response to adrenergic stimuli in the mesenteric and renal arteries of neonatal lambs.

Animals↗
PubMed1980

Tachyphylaxis to inhaled isoproterenol and the effect of methylprednisolone in dogs.

Acute tachyphylaxis can be induced to inhaled isoproterenol (ISO) in anesthetized, closed-chested mongrel dogs. The responsiveness to ISO measured as the percent reduction in methacholine-induced bronchoconstriction was decreased significantly (p less than 0.01) after a 1-hr period of repeated ISO inhalations (ISO-loading). Intravenous administration of methylprednisolone (1 mg/kg) reversed the decrease in responsiveness to ISO.

Animals↗
PubMed1979

Effects of prostaglandin E1 and indomethacin on fetal and neonatal lamb mesenteric artery responses to norepinephrine.

The effects of prostaglandin E1 (PGE1) and indomethacin on isolated fetal and neonatal lamb mesenteric artery responses to norepinephrine were investigated. PGE1 (1.5 micrometer) significantly reduced vasoconstriction responses to 0.5 to 5 micrometer norepinephrine. Indomethacin (1 micrometer) markedly potentiated the constrictor effects of 0.5 to 10 micrometer norepinephrine. PGE1 prevented the potentiating effect of indomethacin. Neither PGE1 nor indomethacin altered basal muscle tension. These results suggest that endogenous PGs modify adrenergic responses in the isolated mesenteric arteries of preterm and newborn lambs.

Animals↗