Use of Body Surface Area to Calculate Chemotherapeutic Drug Dose in Dogs: II. Limitations Imposed by Pharmacokinetic Factors

Anticancer drug dosages that specify the maximum dose and minimum dosing interval that are tolerated in a population of dogs are commonly recommended. Because the differences between the effective and toxic doses of most cancer chemotherapeutics is slight, it is important to achieve therapeutic concentrations in tumor tissues at the same time that concentrations in nontarget tissues are minimized. In order to determine the dosage regimen that will most likely accomplish these goals, similar drug concentrations must be achieved in all patients dosed according to a specific regimen. Dosing based on body surface area (BSA) is generally used in an effort to normalize drug concentrations. This is because it is well recognized that measures of many physiologic parameters that are responsible for drug disposition, including renal function and energy expenditure, can be normalized by use of BSA. However, there is substantial evidence that drug disposition is not always proportional to BSA. Differences in distribution, metabolism, and excretion pathways may preclude dose extrapolation among species or among individuals within a species based on BSA. Moreover, genetic differences in drug metabolism are well recognized in humans and in laboratory animals, and it is likely that similar differences exist among breeds of dogs. A review of the pharmacokinetic disposition of several cancer chemotherapeutics suggests that studies are needed to determine the most effective method to achieve equivalent anticancer drug concentrations in diverse veterinary patients.     

The T963C mutation of TP53 gene does not participate in the clonal origin of canine TVT

In dogs, the canine transmissible venereal tumor (CTVT) is the only neoplasm which is not produced by neoplastic transformation of normal cells; the tumor is transmitted from the affected dog to healthy dogs by implantation of one or various clones of cancer cells. Thus, the CTVT of dogs analyzed in various countries reveals similar genetic characteristics and consequently CTVT is considered to have a clonal origin.The CTVTs obtained from dogs in Korea showed the T963C mutation on TP53 gene; this mutation was thought to be a molecular alteration which participates in the origin of the ancestral clone, CTVT. Nonetheless, this supposed mutation has not been identified in other studies which were carried out for the purpose of clarifying the clonal origin of CTVT. Thus we have considered it important to identify the role of the T963C mutation of the TP53 gene in the clonal origin of CTVT in dogs.Consequently the region which includes the mutation of the TP53 gene in twenty samples of CTVT obtained from various canine breeds was PCR amplified and afterwards its sequence of nucleotides was determined. We conclude that this mutation did not participate in the clonal origin of the tumor, but was acquired at a later stage.     

Stage migration in dogs with lymphoma

BACKGROUND: Various diagnostic tests have been used to assign a clinical stage to dogs with lymphoma. As more sensitive staging methods are introduced, dogs are reclassified as having a higher disease stage, thereby affecting comparisons of dogs across differently staged clinical trials, and possibly, prognosis. HYPOTHESIS: The addition of more sensitive staging tests causes stage migration in dogs with lymphoma. ANIMALS: Fifty-nine client-owned dogs with previously untreated cytologically or histologically confirmed lymphoma METHODS: For every dog, the World Health Organization stage classification (I-V) was based on 5 groupings of various diagnostic tests: A (physical examination [PE] and quantitative blood count [QBC]), B (PE, QBC, thoracic and abdominal radiographs), C (PE, complete blood count with blood-smear evaluation [CBC], thoracic and abdominal radiographs), D (PE, CBC, thoracic radiographs, abdominal ultrasound), and E (PE, CBC, thoracic radiographs, abdominal ultrasound, and bone-marrow cytology). Dogs were treated with doxorubicin-based protocols. RESULTS: There was migration between all of the staging methods except D to E. However, the stage was not a predictor of remission rate, remission duration, or survival, regardless of staging method used. CONCLUSIONS AND CLINICAL IMPORTANCE: These data emphasized the need for standardized methods to determine the clinical stage in dogs with lymphoma.     

Expression of receptor activator of nuclear factor kappa-B ligand (RANKL) in neoplasms of dogs and cats

BACKGROUND: Receptor activator of nuclear factor kappa-B (RANK), RANK-ligand (RANKL), and the soluble decoy receptor osteoprotegerin (OPG) form a key axis modulating osteoclastogenesis. In health, RANKL-expressing bone stromal cells and osteoblasts activate osteoclasts through RANK ligation, resulting in homeostatic bone resorption. Skeletal tumors of dogs and cats, whether primary or metastatic, may express RANKL and directly induce malignant osteolysis. HYPOTHESIS: Bone malignancies of dogs and cats may express RANKL, thereby contributing to pathologic bone resorption and pain. Furthermore, relative RANKL expression in bone tumors may correlate with radiographic characteristics of bone pathology. ANIMALS: Forty-two dogs and 6 cats with spontaneously-occurring tumors involving bones or soft tissues were evaluated. METHODS: A polyclonal anti-human RANKL antibody was validated for use in canine and feline cells by flow cytometry and immunocytochemistry. Fifty cytologic specimens were collected from bone and soft tissue tumors of 48 tumor-bearing animals and assessed for RANKL expression. In 15 canine osteosarcoma (OSA) samples, relative RANKL expression was correlated with radiographic characteristics of bone pathology. RESULTS: Expression of RANKL by neoplastic cells was identified in 32/44 canine and 5/6 feline tumor samples. In 15 dogs with OSA, relative RANKL expression did not correlate with either radiographic osteolysis or bone mineral density as assessed by dual energy x-ray absorptiometry. CONCLUSIONS AND CLINICAL IMPORTANCE: In dogs and cats, tumors classically involving bone and causing pain, often may express RANKL. Confirming RANKL expression in tumors is a necessary step toward the rational institution of novel therapies targeting malignant osteolysis via RANKL antagonism.     

Mushroom-derived maitake PETfraction as single agent for the treatment of lymphoma in dogs

BACKGROUND: Maitake PETfraction is a standardized essence extracted from the mushroom Maitake (Grifola frondosa) that has antitumor activity in tumor-bearing mice. In addition, PETfraction induces apoptosis in human prostate and bladder cancer cells and suppresses the proliferation in vitro of several canine tumor cell lines, such as lymphoma (Cl-1), mammary gland (CF33), and connective tissue (CF21). HYPOTHESIS: Maitake PETfraction is effective as a single agent in dogs with lymphoma. ANIMALS: Fifteen dogs with confirmed intermediate or high-grade lymphoma were enrolled into this prospective, noncontrolled, clinical trial. Inclusion criteria were an expected survival time of at least 2 weeks and no major organ dysfunction. METHODS: Maitake PETfraction was administered at a dose of 3 drops/kg/day divided into 2 doses given 1 hour before feeding. Dogs were evaluated by physical examination with tumor measurement, body weight, CBC, and chemistry profile before treatment and after 2, 4, 8, and 12 weeks. At each visit, owners completed a questionnaire addressing overall quality of life, appetite, and any adverse effects noted. RESULTS: A decrease in lymph node size of greater than 50% (objective response) was not seen in any of the dogs. Thirteen dogs developed progressive disease before the 4th week. The median treatment duration was 27 days (range, 9-228). PETfraction was well accepted, and minimal adverse effects were observed. Two dogs developed hyphema. It was not known if this was related to progressive lymphoma or was an adverse effect of treatment. CONCLUSIONS: No objective responses were observed to administration of Maitake PETfraction, and the drug was well tolerated in these dogs.     

Comparison of 3 protocols for treatment after induction of remission in dogs with lymphoma

BACKGROUND: The optimal treatment after inducing complete remission (CR) in dogs with lymphoma has not been established. HYPOTHESIS: After inducing CR with L-asparaginase, vincristine, cyclophosphamide, doxorubicin, prednisone (L-CHOP); consolidation with either half-body radiation therapy (HBRT); or lomustine (CCNU) and mechlorethamine, vincristine, procarbazine, prednisone (MOPP) would improve first remission duration compared with continuing a CHOP-based protocol for an additional 4 months. ANIMALS: Dogs with stage III-V lymphoma. METHODS: Prospective clinical trial in which dogs initially were treated with an 8-week induction protocol that consisted of L-CHOP. Dogs in CR after induction were then allocated to 1 of 2 consolidation arms. A chemotherapy consolidation arm consisted of 2 treatments with CCNU and 1 cycle of MOPP. A HBRT arm consisted of 2 sequential 8.0-Gy fractions to the cranial and caudal half-body separated by 30 days. Vincristine was given between fractions. Results of the consolidation arms also were compared with a historical group treated with the same 8-week induction protocol followed by CHOP therapy until week 24. RESULTS: Overall, 67% of the dogs were in CR after 8 weeks of induction chemotherapy and were compared. Fifty-two dogs were in the historical arm, 23 in the CCNU/MOPP arm, and 27 in the HBRT arm. No difference in first remission duration was found among groups. Median first remission duration for the historical, CCNU/MOPP, and HBRT arms were 307, 274, and 209 days, respectively (P = .28). Overall second CR rate was 82% and was not different among groups (all P > or = .58). Overall remission duration (P = .28) and survival time (P = .48) were not different among groups. CONCLUSIONS AND CLINICAL IMPORTANCE: Consolidation with either CCNU/MOPP or HBRT showed no advantage over a standard CHOP-based protocol.     

Risk assessment of pesticide residues in South African raw wheat

The presence of pesticide residues in wheat produced and imported in South Africa was determined and their health risks assessed. Pesticides were detected in all local (median = 1, range: 1–3, n = 71) and imported (median = 1, range: 1–6, n = 13) samples. Multiple pesticides (>1 pesticide) were detected in about 30% local samples and 39% imported samples. Eight different pesticides were detected in total. The most frequently detected pesticides were mercaptothion (99%), permethrin (19%) and chlorpyrifos (17%). Nine (11%) samples exceeded the EU wheat MRL for permethrin (0.05 mg/kg) which included 7 (10%) local samples and 2 (15%) imported samples. The highest fenitrothion level (0.65 mg/kg) corresponds to an intake that was below but near the estimated short-term safety threshold. The results call for an investigation into the levels of pesticide residues in cereal-based food and for tighter regulation and regular monitoring by government and industry.     

In vitro cytotoxic activity of Brazilian plant extracts against human lung, colon and CNS solid cancers and leukemia

The cytotoxicity of extracts obtained from plants occurring in the Amazon and Atlantic rain forests against NCI-H460, KM-12, SF-268 and RPMI-8226 cancer cell lines was investigated. Expressive activity was observed in the extracts of Toulicia cf. pulvinata, Ampirrhox sp., Macoubea sprucei, Calophyllum brasiliense, Vismia guianensis, Caryocar microcarpum, Xylopia aromatica and Distictella magnoliifolia.     

Bacterial septicaemia in prerecruit edible crabs,Cancer pagurus L.

Juvenile edible crabs, Cancer pagurus L., were surveyed from Mumbles Head and Oxwich Bay in South Wales, UK, and the number of heterotrophic bacteria and vibrios in the hemolymph was determined. The percentage of crabs with hemolymph containing bacteria was variable over the survey with higher numbers of animals affected in summer than in winter. Post‐moult crabs contained significantly higher numbers of heterotrophic bacteria in the hemolymph than pre‐ and intermoult animals. Crabs with cuticular damage to the gills also had significantly higher numbers of bacteria in the hemolymph. Crabs were found to have a high prevalence of infection by the dinoflagellate, Hematodinium. Such animals had significantly fewer bacteria in the blood in comparison with Hematodinium‐free animals. Of the 463 crabs surveyed, only 3 individuals had hemolymph containing 2000 + CFU mL^?1. Based on 16S rRNA gene sequences, two of these crabs contained a Vibrio pectenicida‐like isolate, while the other had a mixed assemblage of vibrios. Although 59% of the crabs surveyed had culturable bacteria in the hemolymph, the majority only had small numbers (<2000 CFU mL^?1), suggesting that such infections may be of limited importance to the sustainability of the crab fishery in this region.     

Let-7a-3p inhibits activity of cancer stem cells in human lung cancer A549 cells by targeting IGF1R

AIM:To study the effect of let-7a-3p on the activity of cancer stem cells in human lung cancer A549 cells and its molecular biological mechanism. METHODS:The exepression levels of let-7a-3p in lung cancer cell lines A549, NCI-H1299, SPC-A1, H1650 and HCC-827, and human normal bronchial epithilial cell line BEAS-2B were compared by RT-qPCR. The lung cancer A549 cells were transfected with let-7a-3p mimic and negative control mimic, as let-7a-3p group and negative control group, respectively, and non-transfected control group was also set up. The content of let-7a-3p in each group was detected by RT-qPCR. Tumor sphere formation assay was used to detect the tumor sphere formation ability in 3 groups of the cancer stem cells. The proportion of cancer stem cells was detected by flow cytometry. The protein levels of NANOG, OCT4 and insulin-like growth factor 1 receptor (IGF1R) were determined by Western blot. The target gene of let-7a-3p was predicted by the bioinformatic method. The relationship between let-7a-3p and IGF1R was analyzed by double luciferase assay. Western blot was used to detect whether IGF1R over-expression antagonized the inhibitory effect of let-7a-3p on the activity of cancer stem cells. A subcutaneous transplantation tumor model was also established and the effect of let-7a-3p in vivo was observed. RESULTS:The expression level of let-7a-3p in the lung cancer cell lines was significantly lower than that in the normal bronchial epithelial cell line (P<0.01). The expression level of let-7a-3p in the A549 cells of let-7a-3p group was significantly up-regulated compared with non-transfected group (P<0.01). The number of tumor spheres in let-7a-3p group was significantly lower than that in non-transfected group. The percentage of CD133⁺ cells in let-7a-3p group was significantly lower than that in non-transfected group (P<0.01). The protein expression of NANOG and OCT4 in let-7a-3p group was significantly lower than that in non-transfected group (P<0.01). Bioinformatic prediction showed that let-7a-3p complementarily matched the 3'-UTR of IGF1R, and IGF1R might be the target gene of let-7a-3p. Luciferase assay confirmed that IGF1R was the direct downstream target gene of let-7a-3p. The protein expression of IGF1R in let-7a-3p group was significantly decreased (P<0.01). Subcutaneously transplantated tumor in let-7a-3p group was significantly smaller than that in non-transfected group. CONCLUSION:Let-7a-3p may affect the expression of lung cancer stem cell-related proteins and inhibit the potential of lung cancer stem cells by down-regulating its downstream target gene IGF1R.