Objective—To determine the effects of lycopene with and without concurrent chemotherapeutic treatment on growth and apoptosis of canine osteosarcoma cells.
Sample Population—Cell cultures of 3 established canine osteosarcoma cell lines (D17, OS 2.4, and HMPOS).
Procedures—Growth curve kinetics and cell cytotoxicosis for various treatment combinations were assessed by use of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. Additionally, cell cycle kinetics and colony-forming soft agar assays were performed to determine the influences of lycopene on the cell cycle and anchorageindependent growth. Western immunoblotting of HMPOS cells was performed to examine signaling and apoptotic pathways implicated in lycopene-induced apoptosis.
Results—Lycopene alone caused mild to pronounced attenuation of cell proliferation of all 3 cell lines as well as apoptosis in HMPOS cells but did not interfere with cell death in response to doxorubicin. Soft agar anchorage-independent growth assays revealed complete inhibition of cell proliferation in 2 of 3 osteosarcoma cell lines. Further investigation into the apoptotic response revealed activation of mitochondrial-induced apoptosis primarily through expression of truncated Bid and a decrease in protein kinase B (ie, AKT) phosphorylation.
Conclusions and Clinical Relevance—Results suggested that lycopene may be beneficial during treatment of osteosarcomas. Lycopene did not negatively or positively affect survival of osteosarcoma cells during doxorubicin treatment and independently induced apoptosis in the HMPOS cell line. These findings warrant further in vitro and in vivo studies into the use of this natural compound as an adjuvant antiproliferative, proapoptotic treatment in dogs with osteosarcoma.
There is considerable confusion in the veterinary profession surrounding the rise in hemp cannabidiol-based animal products and what veterinarians should know before discussing these products with clients. There is emerging evidence for the potential use in case management across many veterinary indications; however, the cannabinoid concentrations and whether these are isolated cannabinoids or whole hemp extracts is difficult to elucidate, even from the published papers. Much like any extract from a plant, there are multiple considerations including quality control, pharmacokinetics in the intended species, microbiological and chemical contamination, and product consistency—all aspects that should be considered before a conversation can begin with a client. The aim of this review is to help practitioners make informed decisions and better facilitate discussions with clients for companion animals kept as pets. This review will not address food animal issues, as established withholding times have yet to be fully researched.
The goal of pharmacokinetic (PK) studies is to provide a basis for appropriate dosing regimens with novel therapeutic agents. With a knowledge of the desired serum concentration for optimum pharmacological effect, the amount and rate of drug administration can be tailored to maintain that concentration based on the 24-hour PK modeling (eg, every 24 hours, every 12 hours) to achieve therapeutic ranges. This dosing and PK information are tailored to maintain that concentration. Typically, these optimum serum concentrations pertain across species. Single-dose PK modeling provides fundamental parameters to suggest dosing regimes. Multiple-dose PK studies provide information on steady-state serum levels to assure that desired therapeutic levels are maintained during chronic administration. Clinical trials using dosing suggested by these PK determinations provide proof that the compound is producing the desired therapeutic effect. A number of PK studies with cannabinoids in humans and domestic animals have been conducted with the goal of determining appropriate clinical use with these plant-derived products. The following review will focus on the PK of cannabidiol (CBD) and the lesser-known precursor of CBD, cannabidiolic acid (CBDA). Although Δ9-tetrahydrocannabinol (THC) has profound pharmacological effects and may be present at variable and potentially violative concentrations in hemp products, PK studies with THC will not be a major consideration. Because, in domestic animals, hemp-CBD products are usually administered orally, that route will be a focus. When available, PK results with CBD administered by other routes will be summarized. In addition, the metabolism of CBD across species appears to be different in carnivorous species compared with omnivorous/herbivorous species (including humans) based on current information, and the preliminary information related to this will be explained with the therapeutic implication being addressed in Currents in One Health by Ukai et al, JAVMA, May 2023.
The endocannabinoid system (ECS) is an integral neuromodulatory system involved in neuronal development, synaptic plasticity, and homeostasis regarding immunity, as well as brain and other physiological functions such as anxiety, pain, metabolic regulation, and bone growth. Cannabis is a plant that contains exogenous cannabinoids, which have the potential for profound interplay within the ECS as enzymatic inhibitors or receptor-mediated interactions. Activation of cannabinoid receptors leads to various intracellular signaling processes that are involved in cellular functions, but those interactions are diverse due to different affinities of each cannabinoid with relevant receptors. Among the exogenous cannabinoids, cannabidiol (CBD) has drawn attention due to its potential anticancer, antiangiogenic, anti-inflammatory, and antiseizure properties using in vitro and in vivo models. Although scientific evidence is limited in dogs, there appears to be cautious optimism regarding the utilization of CBD in conjunction with other therapeutics for a range of disorders. This review will primarily focus on current scientific research on the efficacy of CBD on seizure, anxiety, osteoarthritis, and atopic dermatitis, following a brief discussion of endo- and exogenous cannabinoids, ECS, their molecular mechanism, and potential side effects in veterinary medicine. Cannabinoid pharmacology and pharmacokinetics will be addressed in the companion Currents in One Health by Schwark and Wakshlag, AJVR, May 2023.
OBJECTIVE To evaluate the effects of adjunctive treatment with autologous platelet-rich plasma (PRP) on corneal reepithelialization, vascularization, and fibrosis in dogs with spontaneous chronic corneal epithelial defects (SCCEDs).
ANIMALS 40 client-owned dogs with uncomplicated SCCEDs.
PROCEDURES All dogs were treated with diamond-burr epithelial debridement (DBD) of affected eyes, topical tobramycin solution and atropine sulfate ointment application, and Elizabethan collar placement for 4 weeks. Dogs were randomly assigned to topical ocular administration of autologous PRP (n = 20) or artificial tear solution (control group; 20) 4 times daily for 28 days. Recheck examinations were performed approximately 2 and 4 weeks after treatment began to evaluate SCCEDs for corneal reepithelialization, and semiquantitative corneal vascularization and corneal fibrosis scores were assigned according to affected corneal surface area. Results were compared between groups.
RESULTS All dogs completed the study. The SCCEDs had completely reepithelialized in 11 (55%) control dogs and 12 (60%) PRP-treated dogs by the 2-week reevaluation, and in 15 (75%) control dogs and 18 (90%) PRP-treated dogs by the 4-week reevaluation. No significant differences were identified between groups in these proportions nor in mean differences from pretreatment scores for corneal vascularization and fibrosis.
CONCLUSIONS AND CLINICAL RELEVANCE In this preliminary study involving dogs with uncomplicated SCCEDs, topical PRP administered as an adjunctive treatment following DBD had no significant effect on healing. A larger study is warranted to support or refute these findings and to determine the effects of adjunctive PRP treatment for dogs with complicated SCCEDs.
Objective—To assess expression pattern and subcellular compartmentalization of 5-lipoxygenase in cutaneous, UV radiation–induced, and oral squamous cell carcinomas (SCCs) in cats and determine the effects of cyclooxygenase or 5-lipoxygenase inhibition on proliferation or apoptosis in a feline oral squamous cell carcinoma (SCCF1) cell line.
Sample—60 archived paraffin-embedded samples of SCCs from 60 cats and SCCF1 cells.
Procedures—Retrospective immunohistochemical analysis of the archived samples of SCCs (20 cutaneous, 20 UV radiation–induced, and 20 oral tumors) was performed. Cell culture proliferation assays involving SCCF1 cells were performed, and tepoxalin-induced apoptosis and signaling were examined via western blotting and annexin V staining.
Results—Immunohistochemically, staining for 5-lipoxygenase was most frequently of greatest intensity in oral SCCs, whereas staining of cutaneous and UV radiation–induced lesions had less consistent 5-lipoxygenase expression. Exposure of SCCF1 cells to the 5-lipoxygenase inhibitor tepoxalin resulted in apoptosis; the effect appeared to be mediated via alteration of cell signaling rather than via suppression of lipid mediators that are typically produced as a result of 5-lipoxygenase activity.
Conclusions and Clinical Relevance—In cats, expression of 5-lipoxygenase in SCCs appeared to differ depending on tumor location. The influence of tepoxalin-induced 5-lipoxygenase inhibition on a 5-lipoxygenase–expressing cell line coupled with the notable expression of 5-lipoxygenase in oral SCCs suggested that 5-lipoxygenase inhibition may have therapeutic benefits in affected cats. Although the safety of tepoxalin in cats has yet to be investigated, 5-lipoxygenase inhibitors should be evaluated for use as a potential treatment for SCCs in that species.
Objective—To determine the effects of the antioxidant astaxanthin on growth of canine osteosarcoma cells with and without concurrent chemotherapeutic or irradiation insult.
Sample Population—Cells from 3 established canine osteosarcoma cell lines (D17, OS 2.4, and HMPOS).
Procedures—Growth-curve kinetics and cell cytotoxic effects were assessed by means of various treatment combinations and a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Western blotting was performed to examine previously identified signaling pathways that astaxanthin reportedly affects. Additionally, cell-cycle kinetic evaluations, soft agar colony-forming assays, and antioxidant assays were performed to better understand the effect of astaxanthin on cell growth and function.
Results—Exposure to astaxanthin alone resulted in a mild to pronounced attenuation of cell proliferation in vitro, depending on the cell line, and did not interfere with the cell-death response to doxorubicin, irradiation, or peroxide-mediated insult. In some instances, astaxanthin acted in an additive fashion to augment cell death. Astaxanthin exposure increased the antioxidant potential of cells, whereas peroxide-mediated cell stress increased the antioxidant potential to the same degree as astaxanthin exposure or greater. No dramatic changes in phosphorylation of protein kinase B or upregulation of connexin 43 were detected.
Conclusions and Clinical Relevance—Findings suggested that astaxanthin administration may be beneficial in treatment of dogs for osteosarcoma. Its actions as an antioxidant did not improve osteosarcoma cell survival during chemotherapeutic or irradiation insults, warranting further research into this natural compound as an adjuvant, antiproliferative treatment for osteosarcoma in dogs.
Objective—To perform respiratory chain enzymatic
activity assays on canine skeletal muscle biopsy specimens
and establish reference range values of skeletal
muscle enzyme activities for dogs.
Sample Population—Biopsy specimens from the
vastus lateralis muscle were obtained from 24 dogs
(8 sexually intact males and 14 sexually intact
females) ranging from 15 months to 6 years of age.
Procedure—Mean values of citrate synthase,
cytochrome-c oxidase, succinate dehydrogenase,
succinate dehydrogenase-cytochrome-c reductase,
nicotinamide adenine dinucleotide (NADH) dehydrogenase,
and NADH dehydrogenase-cytochrome-c
reductase activities were established by use of 6
standard spectrophotometric assays for respiratory
chain enzyme analysis.
Results—Compared with published data for skeletal
muscle enzyme activities in humans, skeletal muscle
enzyme activities in dogs were 2- to 4-fold higher.
Additionally, citrate synthase activity, a marker for
mitochondrial volume, was positively correlated with
age in dogs, suggesting that mitochondrial volume
increases with age, although no apparent change in
respiratory chain enzymatic activity with an increase
in age was found.
Conclusions and Clinical Relevance—Reference
range values for skeletal muscle enzyme activities of
dogs are needed to accurately interpret results of respiratory
chain enzymatic activity assays. During investigation
of metabolic myopathies, if skeletal muscle
biopsy specimens are evaluated for respiratory chain
enzyme kinetics, they should be performed and evaluated
in concert with skeletal muscle biopsy specimens
from clinically normal animals of the same
species. (Am J Vet Res 2004;65:480–484)
Objective—To determine whether long-distance endurance exercise in sled dogs causes increases in serum concentrations of C-reactive protein (CRP) and whether such increases are correlated with other markers of the exercise-induced acute-phase response
Animals—25 sled dogs.
Procedures—Serum was obtained from 25 sled dogs approximately 48 hours before and immediately after completing a race of 557 km. Serum was analyzed to determine concentrations of CRP and interleukin (IL)-6, and serum biochemical analysis (and iron homeostasis analysis) also was performed.
Results—CRP concentrations increased significantly from a mean ± SD concentration of 22.4 ± 16.3 μg/mL before racing to a mean of 263.3 ± 103.8 μg/mL immediately after racing Serum IL-6 concentrations were unchanged; however, there was a modest but significant correlation (r = 0.50) between the increase in CRP concentration and an overall decrease in serum albumin concentration, which suggested an inverse relationship between hepatic synthesis of the 2 proteins. Differences in CRP concentrations among teams of dogs revealed that concentrations before racing may be influenced by previous episodes of exercise. Serum iron concentration had only a mild decrease, which may have been attributable to iron-rich diets consumed by the dogs.
Conclusions and Clinical Relevance—CRP concentrations may serve as a potential marker for exercise-induced inflammation. The exact amount of exercise required to induce such a response is unknown, but dogs apparently have a more robust acute-phase response than do humans. Clinical evaluation of CRP concentrations must account for physical activity when those concentrations are used as a potential marker for systemic inflammation. (Am J Vet Res 2010;71:1207-1213)
Objective—To evaluate differences in hepatic copper concentrations in Labrador Retrievers with and without chronic hepatitis.
Design—Retrospective case-control study.
Sample—Liver tissue specimens from 36 Labrador Retrievers with chronic hepatitis and 36 age- and sex-matched Labrador Retrievers without chronic hepatitis (control dogs).
Procedures—Liver tissue specimens were obtained during 2 study periods (1980 to 1997 and 1998 to 2010). For each tissue specimen, a histologic score was assigned independently by each of 2 interpreters, and the hepatic copper concentration was qualitatively determined via rhodanine staining and quantitatively determined via atomic absorption spectroscopy.
Results—Mean hepatic copper concentration was significantly higher in dogs with chronic hepatitis (614 μg/g of dry weight [range, 104 to 4,234 μg/g of dry weight]), compared with that in control dogs (299 μg/g of dry weight [range, 93 to 3,810 μg/g of dry weight]), and increased significantly over time. A higher proportion of liver tissue specimens collected during the 1998–2010 study period had hepatic copper concentrations > 400 μg/g of dry weight (the upper limit of the reference range), compared with the proportion of liver tissue specimens collected during the 1980–1997 study period. The qualitative copper score did not accurately predict quantitative hepatic copper concentration in 33% of study dogs.
Conclusions and Clinical Relevance—Results suggested that the increase in hepatic copper concentrations in Labrador Retrievers with and without chronic hepatitis over time may be the result of increased exposure of dogs to environmental copper, most likely via the diet.