Rebekah DeVinney

Bio: Rebekah DeVinney is an academic researcher from University of California, San Francisco. The author has contributed to research in topics: Mastocytoma & Chondroitin sulfate. The author has an hindex of 3, co-authored 4 publications receiving 134 citations.

Establishment of Two Dog Mastocytoma Cell Lines in Continuous Culture

Abstract: We have previously characterized dog mastocytoma cells propagated in nude mice. We have established two of these lines (C1 and C2) in continuous culture. Freshly disaggregated mastocytoma cells were cultured in Dulbecco's modified Eagle's medium (DME)-H16 mixed with 50% Ham's F12 and supplemented with histidine and 5% allergic dog serum (ADS). Cells were fed every 3 d and passaged weekly. Growth was assessed by cell count. Cell growth was best supported by culture in 5% ADS. C1 cells grow in suspension in ADS and have been passaged 55 times with a doubling time of 37.4 ± 18.7 h (mean ± 1 SD; n = 15). C2 cells adhere to tissue culture plastic in ADS and have been passaged 26 times with a doubling time of 49.3 ± 12.5 h (n = 13). Morphologic and functional characteristics are unchanged from those described in cells propagated in nude mice. Histamine content for C1 is 0.46 ± 0.18 pg/cell (n = 12) and 0.07 ± 0.04 pg/cell (n = 6) for C2. Both lines contain the neutral protease tryptase and C2 contains chymase. ...

Isolated canine mastocytoma cells: propagation and characterization of two cell lines.

Abstract: Five different dog mastocytoma tumors were successfully transplanted and propagated in BALB/c nude mice. Cells from two of these tumors were passaged serially through at least four generations of mice without morphological or functional change. The average yield from a 2-cm tumor harvested from a mouse was 1.2 +/- 2.8 X 10(9) mast cells with greater than 90% viability. Cells of one line were larger and more heavily granulated than the other, and contained 1.29 +/- 0.74 pg histamine/cell (mean +/- SD). Calcium ionophore A23187 and compound 48/80 caused dose dependent histamine release with no significant difference in release from generation to generation. The smaller cells contained 0.06 +/- 0.06 pg histamine/cell. Histamine release after calcium ionophore or compound 48/80 was dose dependent and unchanged through serial passages. Following passive sensitization antigen caused dose-dependent histamine release confirming the presence of IgE receptors on these cells. In both cell lines histamine release was inhibited by terbutaline, dibutyryl adenosine 3',5'-cyclic monophosphate, or isobutylmethylxanthine. These methods provide a morphologically and functionally stable population of nearly pure canine mast cells for biochemical and physiological studies.

Both heparin and chondroitin sulfate proteoglycans are intracellular components of dog mastocytoma cell lines

Abstract: Intracellular proteoglycans (PG), putative markers of mast cell subtype, were isolated and characterized from three dog mastocytome cell lines. Mastocytoma cells were adapted to serial passage as subcutaneous tumors in BALB/c nude mice for 10 generations. Cells were disaggregated and labeled with (number/sup 5/S)SO/sub 4/ in culture. Intracellular /sup 35/S-labeled PG were isolated by sonication in 4M guanidine containing protease and glycosidase inhibitors, then chromatographed on Sepharose CL-4B. All 3 cell lines yielded a major /sup 35/S component at the Vo (Mr greater than or equal to 10/sup 6/). Excluded fractions were treated with alkaline-borohydride and the liberated glycosaminoglycans (GAG) were analyzed on Sephacryl S-200. GAG chains had an apparent Mr of 40-50,000. GAG chains were subjected to chondroitinase ABC and nitrous acid degradation and the products were analyzed on Sepharcyl S-200. In one cell line (BR), 75% of /sup 35/S-labeled GAG was resistant to chondroitinase treatment, but was degraded by nitrous acid, characteristic of heparin. The remaining 25% of /sup 35/S-labeled GAG was degraded to oligosaccharides by chondroitinase indicating chondroitin sulfate (CS). A second cell line (G) also contained both heparin and CS-PG. The remaining cell line (C2) contained 2% heparin-PG and 98% CS-PG. The results demonstrate the simultaneousmore » presence of both heparin and CS-PG in mast cells of clonal origin, and raise important questions on the role of PGs in mast cell granule storage and release mechanisms.« less

Multi-center, Placebo-controlled, Double-blind, Randomized Study of Oral Toceranib Phosphate (SU11654), a Receptor Tyrosine Kinase Inhibitor, for the Treatment of Dogs with Recurrent (Either Local or Distant) Mast Cell Tumor Following Surgical Excision

Abstract: Purpose: The purpose of this study was to determine the objective response rate (ORR) following treatment of canine mast cell tumors (MCT) with toceranib phosphate (Palla- dia, SU11654), a kinase inhibitor with both antitumor and antiangiogenic activity through inhibition of KIT, vascular endothelial growth factor receptor 2, and PDGFRβ. Secondary objectives were to determine biological response rate, time to tumor progression, dura- tion of objective response, health-related quality of life, and safety of Palladia. Experimental Design: Dogs were randomized to receive oral Palladia 3.25 mg/kg or pla- cebo every other day for 6 weeks in the blinded phase. Thereafter, eligible dogs re- ceived open-label Palladia. Results: The blinded phase ORR in Palladia-treated dogs (n = 86) was 37.2% (7 com- plete response, 25 partial response) versus 7.9% (5 partial response) in placebo-treated dogs (n = 63; P = 0.0004). Of 58 dogs that received Palladia following placebo-escape, 41.4% (8 complete response, 16 partial response) experienced objective response. The ORR for all 145 dogs receiving Palladia was 42.8% (21 complete response, 41 partial response); among the 62 responders, the median duration of objective response and time to tumor progression was 12.0 weeks and 18.1 weeks, respectively. Palladia-treated responders scored higher on health-related quality of life versus Palladia-treated nonresponders (P = 0.030). There was no significant difference in the number of dogs with grade 3/4 (of 4) adverse events; adverse events were generally manageable with dose modification and/or supportive care. Conclusions: Palladia has biological activity against canine MCTs and can be adminis- tered on a continuous schedule without need for routine planned treatment breaks. This clinical trial further shows that spontaneous tumors in dogs are good models to evaluate therapeutic index of targeted therapeutics in a clinical setting. Mast cell tumors (MCT) are the second most common malig- nant tumors in dogs. Most originate in the skin or s.c. tissues but they can occur as primary tumors in the intestines, liver, or spleen (1). Canine MCTs possess a wide range of biological

Mast cell tryptase causes airway smooth muscle hyperresponsiveness in dogs.

Abstract: Supernatants obtained by degranulation of dog mastocytoma cells greatly increased the sensitivity and the magnitude of the contractile response of isolated dog bronchial smooth muscle to histamine. The enhanced contractile response was reversed completely by H1-receptor antagonists and was prevented by an inhibitor of tryptase (a major protease released with histamine from secretory granules of mast cells). The potentiation of histamine-induced contractions was reproduced by active tryptase in pure form. The contractions due to the combination of histamine and purified tryptase were abolished by the Ca2+ channel blockers nifedipine and verapamil. The bronchoconstricting effects of KCl and serotonin, which, like histamine, contract airway smooth muscle by a mechanism predominantly involving membrane potential-dependent Ca2+ transport, were also potentiated by tryptase. However, the contractile effects of acetylcholine, which contracts dog airway smooth muscle by a mechanism independent of Ca2+ channels, were unaffected by tryptase. These findings show a striking promotion of agonist-induced bronchial smooth muscle contraction by mast cell tryptase, via direct or indirect effects on Ca2+ channels, and the findings therefore suggest a novel potential mechanism of hyperresponsiveness in dog bronchi.