Influence of Various Factors on Circulating 25(OH) Vitamin D Concentrations in Dogs with Cancer and Healthy Dogs.

BACKGROUND: Low blood 25-hydroxyvitamin D (25(OH)D) concentrations have been associated with cancer in dogs. Little research has examined what other factors may affect 25(OH)D concentrations. OBJECTIVES: (1) To determine whether the presence of cancer (lymphoma, osteosarcoma, or mast cell tumor [MCT]) in dogs is associated with plasma 25(OH)D concentrations and (2) identify other factors related to plasma 25(OH)D concentrations in dogs. ANIMALS: Dogs newly diagnosed with osteosarcoma (n = 21), lymphoma (n = 27), and MCT (n = 21) presented to a tertiary referral oncology center, and healthy, client-owned dogs (n = 23). METHODS: An observational study design was used. Dietary vitamin D intake, sex, age, body condition score (BCS), muscle condition score (MCS), and plasma concentrations of 25(OH)D, 24,25-dihydroxyvitamin D (24,25(OH)2 D) (a marker of CYP24A1 activity), as well as ionized calcium (ICa), parathyroid hormone, and parathyroid hormone-related protein concentrations were measured. An analysis of covariance was used to model plasma 25(OH)D concentrations. RESULTS: Cancer type (P = 0.004), plasma 24,25(OH)2 D concentrations (P < 0.001), and plasma ICa concentrations (P = 0.047) had significant effects on plasma 25(OH)D concentrations. Effects of age, sex, body weight, BCS, MCS, and plasma PTH concentrations were not identified. A significant interaction between ICa and cancer was found (P = 0.005). Plasma 25(OH)D concentrations increased as ICa concentrations increased in dogs with cancer, whereas plasma 25(OH)D concentrations decreased as ICa concentrations increased in healthy dogs. CONCLUSIONS AND CLINICAL IMPORTANCE: Results support a relationship between cancer and altered vitamin D metabolism in dogs, mediated by plasma ICa concentrations. The CYP24A1 activity and plasma ICa should be measured in studies examining plasma 25(OH)D concentrations in dogs.

Adverse haematological effects of vinblastine, prednisolone and cimetidine treatment: a retrospective study in fourteen dogs with mast cell tumours.

Vinblastine toxicity is poorly documented in dogs. The aim of this study was to investigate the haematological alterations in dogs treated with vinblastine and prednisolone. Fourteen dogs with mast cell tumours (MCT) were selected on at least one of the following criteria: lymph node infiltration, surgical margin infiltration, grade II MCTs with Ki-67 >10%, and grade III MCTs. Starting 15 days after surgery, the dogs were given vinblastine (2 mg/m2 i.v. four times weekly, then twice monthly for 2 months) and prednisolone (2 mg/kg/day p.o.). An EDTA blood sample was collected weekly for complete blood count (CBC). A total of 98 doses of vinblastine were given to the 14 dogs and 114 CBC were performed. Abnormal haematological findings were observed in 12 CBCs from five dogs, which represent a prevalence of 20% of the total CBCs performed in these animals. The most prevalent abnormal finding was thrombopenia (9/12) most often with grade I toxicity (6/9). In conclusion, the risk of occurrence of adverse haematological effects resulting from vinblastine-prednisolone treatment seems limited in dogs with MCT and it should not be overestimated.

Relationship of disease progression and plasma histamine concentrations in 11 dogs with mast cell tumors.

Plasma histamine concentrations (PHCs) were measured serially over 9 months or until death in 11 dogs with mast cell tumors (MCTs). Eight dogs had grossly visible disease and the other 3 dogs had microscopic disease. Initial PHCs in the dogs with gross disease were significantly higher than PHCs in healthy dogs (median, 0.73 ng/mL and 0.19 ng/mL respectively; P < .009), whereas initial PHCs in dogs with microscopic disease showed no difference from controls. Seven dogs subsequently had progressive increases in PHC, and developed hyperhistaminemia (median, 14.0 ng/mL; range, 5.11-30.1 ng/nL). These 7 dogs died from MCTs, and 1 had general weakness with rapid lysis of a large tumor burden after radiation therapy. PHCs of the other 4 dogs were less than 1 ng/mL during the study. These 4 dogs were still alive with adequate control of the tumor at the conclusion of the study. Four of the 11 dogs initially had gastrointestinal (G1) signs, which abated soon after administration of histamine-2 (H-2) blockers. No significant difference was found between PHCs in dogs with GI signs and those without GI signs (median, 0.86 ng/mL and 0.35 ng/mL. respectively). Thereafter, 7 dogs had serious GI complications for which H-2 blocker therapy was ineffective. PHCs in these 7 dogs were extremely high (median, 12.2 ng/mL; range, 3.42-30.1 ng/nL). Results of this study demonsrated that PHC was one factor related to disease progression, and indicated that marked hyperhistaminemia was associated with the GI signs refractory to H-2 blocker therapy in dogs with MCTs.

Frequency and severity of mastocytemia in dogs with and without mast cell tumors: 120 cases (1995-1997).

OBJECTIVE: To elucidate frequency of detection on blood smears and severity on quantitative buffy coat evaluation of mastocytemia between dogs without mast cell tumors (MCT) and dogs that had MCT, and to expand the list of diseases associated with mastocytemia in dogs without MCT. DESIGN: Retrospective study. ANIMALS: 94 dogs without MCT and 26 dogs with MCT. PROCEDURE: Medical records of all dogs with mast cells detected on blood or buffy coat smears during a 2-year period were reviewed. Dogs with mastocytemia were grouped by disease into dogs with MCT and dogs without MCT. Twenty-five of the dogs without MCT that had mast cells detected on blood smears also had evaluations of buffy coat smears. Quantitative buffy coat results of the 25 dogs without MCT were compared with those of the 26 dogs with MCT. RESULTS: 95.5% of blood smears with mast cells detected during CBC determination were from dogs without MCT. For these dogs, diagnoses included inflammatory disease (28.2%), regenerative anemia (27%), neoplasia other than MCT (25.9%), and trauma (11.8%). Dogs with MCT had a mean of 71.4 mast cells/buffy coat smear, whereas dogs without MCT had a mean of 276.2 mast cells/buffy coat smear. The 2 highest counts of mast cells/buffy coat smear were for dogs without MCT. CONCLUSIONS AND CLINICAL RELEVANCE: On the basis of results of quantitative buffy coat evaluations, severity of mastocytemia in dogs without MCT often exceeds that detected during tumor staging in dogs with MCT. Random detection of mast cells in blood smears during CBC determination in dogs is usually not secondary to MCT.

High frequency of specific CD8+ T cells in the tumor and blood is associated with efficient local IL-12 gene therapy of cancer.

Cancer immunotherapy often aims at the reactivation and expansion of tumor-specific CTL. In an attempt to correlate in situ and/or systemic tumor-specific T cell expansion with tumor regression, we investigated the effects of adenovirus-mediated IL-12 or IFN-gamma gene transfer into established P815 murine tumors. While IFN-gamma was no more potent than the vector alone, IL-12 gene transfer promoted tumor eradication. Despite this antitumor effect, no significant cytolytic activity was detectable using classical cytotoxicity assays from in vitro restimulated splenocytes. Since intratumor gene delivery may induce a localized expansion of CTL, the presence of P815-specific CD8+ T cells in situ was assessed. Using the Immunoscope approach, we found a dramatic increase in clonotypic T cells at the tumor site following IL-12, but not IFN-gamma gene delivery. Antitumor CD8+ T cell frequencies were then re-evaluated using this molecular detection technique, which revealed a comparable expansion of specific T cells in the peripheral organs, most strikingly in the blood. These data show that local IL-12 gene transfer, in contrast to IFN-gamma, mediates a potent antitumor effect that correlates to clonal tumor-specific T cell expansions in situ and in the periphery.

A case of malignant mastocytosis with circulating mast cell precursors: biologic and phenotypic characterization of the malignant clone.

The phenotypic and biologic properties of malignant cells in a case of aggressive mastocytosis with multi-organ involvement, circulating mast cell precursors and absence of skin infiltrates were analyzed. Circulating mast cell precursors were detected by immunostaining using antibodies against mast cell tryptase as well as by electron microscopy. These progenitors were tryptase+/chymase- (MCT) and accounted for 10 to 20% of nucleated mononuclear blood cells (MNC). A subset of them contained metachromatic granules. As assessed by combined toluidine blue/immunofluorescence staining, the granulated mast cell precursors were found to express CD9 (P24), CD33 (gp67) and CD44 (Pgp-1), but not basophil-related markers (CD11b (C3biR), CDw17 (lactosylceramide), CD123 (il-3R alpha))or monocyte-related antigens (CD14, CD15). Expression of the mast cell growth factor (MGF) receptor, c-kit(CD117), was also demonstrable, whereas the skin mast cell marker C5aR (CD88) could not be detected on mast cell precursors. The ligand of c-kit, recombinant human (rh) stem cell factor (SCF = MGF), induced histamine release from circulating mast cell progenitors, whereas rhC5a, a potent skin mast cell-/basophil-agonist, was ineffective over the dose-range (10(-9) to 10(-7(M)) tested. Analysis of mast cell antigens in malignant mastocytosis or mast cell leukemias may be helpful to establish a diagnosis and to determine the phenotype of the clone.

Plasma histamine and gastrin concentrations in 17 dogs with mast cell tumors.

Dogs with mast cell tumors (MCT) are often affected with paraneoplastic syndromes such as gastrointestinal ulceration. The mechanism of ulceration is believed to be related to hyperhistaminemia. To test this hypothesis, plasma histamine and gastrin concentrations were measured in 17 dogs with MCT. Plasma histamine concentrations in dogs with MCT were significantly higher than those in normal dogs. Conversely, plasma gastrin concentrations in dogs with MCT were significantly lower than gastrin concentrations in normal dogs. Additionally, plasma gastrin concentrations were inversely related to plasma histamine concentrations, which provided indirect evidence for the presence of hyperacidity secondary to hyperhistaminemia (r2 = 57.7). Plasma histamine and plasma gastrin concentrations were not related to clinical stage of disease, tumor histologic grade, or tumor size. Median survival time was 245 days, with a range of 90 to 1315 days. Because the degree of hyperhistaminemia could not be predicted in this study from the clinical stage, histologic grade, or tumor size, these data suggest that hyperhistaminemia may occur in any dog with MCT.

3' processing of pre-mRNA plays a major role in proliferation-dependent regulation of histone gene expression.

A short histone-like fusion RNA, generated when the RNA 3' processing signal from a mouse histone H4 gene is inserted into a heterologous transcription unit, becomes correctly down-regulated in G1-arrested cells of a temperature-sensitive mouse mastocytoma cell cycle mutant (21-Tb; Stauber et al., EMBO J. 5, 3297-3303 [1986]), due to a specific deficiency in histone RNA processing (Lüscher and Schümperli, EMBO J. 6, 1721-1726 [1987]). In contrast, inhibitors of DNA synthesis, known to stimulate histone mRNA degradation, have little or no effect on the fusion RNA. This RNA can therefore be used to discriminate between regulation by RNA 3' processing and RNA stability, respectively. The fusion RNA is also faithfully regulated in 21-Tb cells arrested in G1 phase by the drug indomethacin or in C127 mouse fibroblasts during a serum starvation experiment. Moreover, nuclear extracts from serum-starved C127 cells show a specific deficiency in a heat-labile component of the histone RNA processing apparatus, similar to that previously observed for temperature-arrested 21-Tb cells. These results suggest that RNA 3' processing is a major determinant for the response of histone mRNA levels to changes in cell proliferation.

Potentiation of the chemotherapeutic action of 5'-deoxy-5-fluorouridine in combination with guanosine and related compounds.

The effect of inosine, guanosine, and guanosine 5'-monophosphate (GMP) on the antitumor activity of 5'-deoxy-5-fluorouridine (5'-DFUR) was investigated using P388 leukemia and P815 mastocytoma. The antitumor activity of 5'-DFUR was markedly enhanced by coadministration of inosine or guanosine. The increase in lifespan (ILS) of mice treated with 5'-DFUR was augmented by the combination with guanosine or inosine in a dose-dependent fashion, and the maximum ILS was about 160% with the combination, while that in the case of 5'-DFUR alone was only 48% in the P388 leukemia system. The therapeutic ratio (dose at ILSmax/dose at ILS30) of the combination with guanosine or inosine was 333 and 136, respectively, whereas that of 5'-DFUR alone was 3.6. GMP also markedly potentiated the antitumor activity of 5'-DFUR in both P388 leukemia and P815 mastocytoma systems, just as it potentiated the activity of 5-fluorouracil in the latter system. The uric acid level in the serum was elevated after IP injection of guanosine or inosine but the value was much lower in the case of guanosine than in inosine.

Hemin stimulating effect on colony formation of leukemic and bone marrow cells.

The hemin enhancing activity on colony formation of leukemic and normal bone-marrow (BM) cells is described. The colony growth of Friend erythroleukemic cells (FL) and mastocytoma cells (M) was markedly enhanced. On the other hand, myeloid leukemic cells (P) and normal bone-marrow cells (BM) were only slightly affected. Inhibition of colony formation was observed with lymphoid leukemic cells (L). For M and BM cells, the horse serum could be replaced by BSA with preservation of hemin enhancing activity.