Explore the vast range of titles available.

Introduction/Background The number of publications for most common drug violations in racehorses is limited. This study reports the most common medication violations in racehorses at four major racetracks in Louisiana between 2016 and 2020. Methods During this 5‐year period, 27,237 blood samples and 25,672 urine samples collected during the course of normal race meeting activities were analysed by initial screening procedure utilizing Liquid Chromatography Mass Spectrometry (LC‐MS/MS). Following initial screening, suspect samples were subject to quantitative or semi‐ quantitative confirmation analysis by LC‐MS/MS. Results The total number of violations reported was 534 (1.01% of the total number of specimens analysed). The total number of violations reported in Thoroughbred horses was 210 while the total number of violations reported in Quarter Horses was 324. The percentage of total violations was %0.59 for all the specimens analysed in Thoroughbred horses while this percentage was %1.9 for all the specimens analysed in Quarter Horses during this 5‐year period. The most frequent violations included the overages (concentrations of permitted medications equal to or exceeding the set threshold) of clenbuterol (165 violations), non‐steroidal anti‐inflammatory drugs (NSAIDs) such as phenylbutazone (73 violations), combination of phenylbutazone with flunixin (45 violations) and muscle relaxant methocarbamol (40 violations). Discussion/Conclusions The total number of violations were relatively low during 5‐year period, but wide varieties of medications with different pharmacological actions were confirmed in performance horses in Louisiana. The most frequently reported violations in Louisiana were for permitted therapeutic medications (clenbuterol, phenylbutazone, flunixin methocarbamol) with established threshold and/or withdrawal guidelines in racehorses. This study reports the most common medication violations in racehorses at four major racetracks in Louisiana between 2016 and 2020. The most frequent violations included the overages (concentrations of permitted medications equal to or exceeding the set threshold) of clenbuterol (165 violations), non‐steroidal anti‐inflammatory drugs (NSAIDs) such as phenylbutazone (73 violations), combination of phenylbutazone with flunixin (45 violations), and muscle relaxant methocarbamol (40 violations).

DNA Alkylation is thought to be the reason for the efficacy of lomustine while carbamylation has been implicated as the cause for the side effects seen with lomustine treatment such as hepatotoxicity. In the alkylation study we show that lomustine and its metabolites form similar levels of the DNA adducts N7 hydroxyethylguanine and O6 hydroxyethyldeoxyguanosine. In terms of carbamylation, lomustine showed greater extent of carbamylation in the canine hepatocytes and lymphoma cell lines. The DNA repair enzyme O6 methylguanine DNA methyltransferase (MGMT) causes resistance of tumor cells to bifunctional nitrosourea, like lomustine. There is no data available regarding MGMT expression/activity in canine cells or tissues. Our study shows that there is low MGMT activity in the canine lymphoid cell line 17–71 while the GL-1 cells did not show any detectable enzyme activity or mRNA expression. The MGMT enzyme activity measured in canine hepatocytes is about 250–350 fmol/mg protein as compared to about 90 fmol/mg protein in 17–71 cells. We also show that MGMT mRNA expression in 17–71 cells and canine hepatocytes positively correlates with its enzyme activity in these cells.

The nitrosourea drug lomustine is used clinically for treating a wide variety of malignancies, most commonly brain tumors and lymphoma. Lomustine undergoes hydrolysis in vivo to form isomeric metabolites, primarily trans-4-hydroxylomustine (trans-4) and cis-4-hydroxylomustine (cis-4) in various animal species including humans. Despite its widespread usage to treat canine lymphoma, the metabolism of lomustine has not been studied in dogs. It is reported that 4'-hydroxylation products of lomustine (trans-4 and cis-4) have enhanced alkylating activity and reduced toxic effects relative to lomustine, resulting in a better therapeutic index of each of the metabolites relative to the parent compound. Our results show that the metabolic profile of lomustine in dogs is similar to that in humans with trans-4 being the major metabolite and cis-4 as the minor metabolite. Comparative cytotoxicity studies of lomustine and its trans-4 and cis-4 metabolites in canine lymphoma cell lines 17–71 and GL-1 show that there is no difference in the cytotoxicity of the three compounds. In addition, a concentration and time-dependent cell killing was seen in both of these cell lines. Also, primary canine cells like peripheral blood mononuclear cells (PBMC) from lymphoma dogs did not show any sensitivity towards lomustine and its metabolites.

Summary Isobutyl-deoxynyboquinone (IB-DNQ) is a selective substrate for NAD(P)H:quinone oxidoreductase (NQO1), an enzyme overexpressed in many solid tumors. Following activation by NQO1, IB-DNQ participates in a catalytic futile reduction/reoxidation cycle with consequent toxic reactive oxygen species generation within the tumor microenvironment. To elucidate the potential of IB-DNQ to serve as a novel anticancer agent, in vitro studies coupled with in vivo pharmacokinetic and toxicologic investigations in the domestic felid species were conducted to investigate the tractability of IB-DNQ as a translationally applicable anticancer agent. First, using feline oral squamous cell carcinoma (OSCC) as a comparative cancer model, expressions of NQO1 were characterized in not only human, but also feline OSCC tissue microarrays. Second, IB-DNQ mediated cytotoxicity in three immortalized feline OSCC cell lines were studied under dose-dependent and sequential exposure conditions. Third, the feasibility of administering IB-DNQ at doses predicted to achieve cytotoxic plasma concentrations and biologically relevant durations of exposure were investigated through pharmacokinetic and tolerability studies in healthy research felines. Intravenous administration of IB-DNQ at 1.0–2.0 mg/kg achieved peak plasma concentrations and durations of exposure reaching or exceeding predicted in vitro cytotoxic concentrations. Clinical adverse side effects including ptyalism and tachypnea exhibited during and post-IV infusion of IB-DNQ were transient and tolerable. Additionally, IB-DNQ administration did not produce acute or delayed-onset unacceptable hematologic, non-hematologic, or off-target oxidative toxicities. Collectively, the findings reported here within provide important safety and pharmacokinetic data to support the continued development of IB-DNQ as a novel anticancer strategy for NQO1 expressing cancers.

This study evaluated the usage of Beckman Coulter AU680 analyzers for measurement of TCO2 in horse serum, and the effect of sodium bicarbonate administrations on serum TCO2 levels in resting horses. Treatment of horses with sodium bicarbonate did not result in any adverse events. Mean TCO2 concentration was significantly higher from 1 to 8 h in the sodium bicarbonate‐treated horses compared to the untreated controls. Within an hour, administration of sodium bicarbonate increased the TCO2 level from 31.5 ± −2.5 (SD) to 34.0 ± 2.65 (SD) mmol/L and at 2–8 h post‐administration, the TCO2 level was above the 36 mmol/L cut‐off level. In all quality control analysis of Australian standard by Beckman Coulter AU680 analyzer, the instrument slightly over estimated the TCO2 level but the values were in close agreement with mean TCO2 level being 38.03 with ± 0.87 mmol/L (SD). Expanded uncertainty was calculated using different levels of confidence interval. Based on 99.5% confidence interval using 0.805% expanded uncertainty using mean measured concentration of 38.05 mmol/L, it was estimated that any race samples TCO2 level higher than 38.5 mmol/L will be indicative of sodium bicarbonate administration using Beckman Coulter AU680 analyzer in Louisiana. This study evaluated the usage of Beckman Coulter AU680 analyzers for measurement of TCO2 in horse serum, and the effect of sodium bicarbonate administrations on serum TCO2 levels in resting horses. Treatment of horses with the “milkshake” did not result in any adverse events. Mean TCO2 concentration was significantly higher from 1‐8 hours in the “milkshake”‐treated horses compared to the untreated controls.

Summary PAC-1 is a preferential small molecule activator of procaspase-3 and has potential to become a novel and effective anticancer agent. The rational development of PAC-1 for translational oncologic applications would be advanced by coupling relevant in vitro cytotoxicity studies with pharmacokinetic investigations conducted in large mammalian models possessing similar metabolism and physiology as people. In the present study, we investigated whether concentrations and exposure durations of PAC-1 that induce cytotoxicity in lymphoma cell lines in vitro can be achievable in healthy dogs through a constant rate infusion (CRI) intravenous delivery strategy. Time- and dose-dependent procaspase-3 activation by PAC-1 with subsequent cytotoxicity was determined in a panel of B-cell lymphoma cells in vitro. The pharmacokinetics of PAC-1 administered orally or intravenously was studied in 6 healthy dogs using a crossover design. The feasibility of maintaining steady state plasma concentration of PAC-1 for 24 or 48 h that paralleled in vitro cytotoxic concentrations was investigated in 4 healthy dogs. In vitro, PAC-1 induced apoptosis in lymphoma cell lines in a time- and dose-dependent manner. The oral bioavailability of PAC-1 was relatively low and highly variable (17.8 ± 9.5%). The achievement and maintenance of predicted PAC-1 cytotoxic concentrations in normal dogs was safely attained via intravenous CRI lasting for 24 or 48 h in duration. Using the dog as a large mammalian model, PAC-1 can be safely administered as an intravenous CRI while achieving predicted in vitro cytotoxic concentrations.

This study evaluated the usage of Beckman Coulter AU 680 analyzers for measurement of TCO 2 in horse serum, and the effect of sodium bicarbonate administrations on serum TCO 2 levels in resting horses. Treatment of horses with sodium bicarbonate did not result in any adverse events. Mean TCO 2 concentration was significantly higher from 1 to 8 h in the sodium bicarbonate‐treated horses compared to the untreated controls. Within an hour, administration of sodium bicarbonate increased the TCO 2 level from 31.5 ± −2.5 ( SD ) to 34.0 ± 2.65 ( SD ) mmol/L and at 2–8 h post‐administration, the TCO 2 level was above the 36 mmol/L cut‐off level. In all quality control analysis of Australian standard by Beckman Coulter AU 680 analyzer, the instrument slightly over estimated the TCO 2 level but the values were in close agreement with mean TCO 2 level being 38.03 with ± 0.87 mmol/L ( SD ). Expanded uncertainty was calculated using different levels of confidence interval. Based on 99.5% confidence interval using 0.805% expanded uncertainty using mean measured concentration of 38.05 mmol/L, it was estimated that any race samples TCO 2 level higher than 38.5 mmol/L will be indicative of sodium bicarbonate administration using Beckman Coulter AU 680 analyzer in Louisiana.

Levent Dirikolu1, Thushara Chakkath1, Susan Ball-Kell2, Christy Elamma2, David J Schaeffer11Department of Comparative Biosciences, 2Veterinary Diagnostic Laboratory, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, USAAbstract: This study evaluated the subchronic toxicity of StemEnhance™, an extract of the blue-green alga Aphanizomenon flos-aquae that is used as a health supplement. Groups of 12 rats of each sex were given either 5% glycerin in water (control) or 200 mg/kg of StemEnhance prepared in 5% glycerin in water for 90 days by oral gavage. The administration of StemEnhance had no effect on behavior, food and water intake, growth, or survival. Values at the end of dosing and observation periods did not reveal differences between treated and control groups for hematology and clinical chemistry. There were no significant differences in the gross and histopathology of the reproductive organs in either males or females. Sperm motility parameters were similar for control and treated males. Our results show that StemEnhance at doses ~7 times the maximum label-recommended daily dose did not produce adverse effects in Wistar rats after subchronic treatment.Keywords: algal toxicology, blue-green algae, cyanobacteria, Aphanizomenon flos-aquae

PAC-1 is a preferential small molecule activator of procaspase-3 and has potential to become a novel and effective anticancer agent. The rational development of PAC-1 for translational oncologic applications would be advanced by coupling relevant in vitro cytotoxicity studies with pharmacokinetic investigations conducted in large mammalian models possessing similar metabolism and physiology as people. In the present study, we investigated whether concentrations and exposure durations of PAC-1 that induce cytotoxicity in lymphoma cell lines in vitro can be achievable in healthy dogs through a constant rate infusion (CRI) intravenous delivery strategy. Time- and dose-dependent procaspase-3 activation by PAC-1 with subsequent cytotoxicity was determined in a panel of B-cell lymphoma cells in vitro. The pharmacokinetics of PAC-1 administered orally or intravenously was studied in 6 healthy dogs using a crossover design. The feasibility of maintaining steady state plasma concentration of PAC-1 for 24 or 48 hours that paralleled in vitro cytotoxic concentrations was investigated in 4 healthy dogs. In vitro, PAC-1 induced apoptosis in lymphoma cell lines in a time- and dose-dependent manner. The oral bioavailability of PAC-1 was relatively low and highly variable (17.8 ± 9.5%). The achievement and maintenance of predicted PAC-1 cytotoxic concentrations in normal dogs was safely attained via intravenous CRI lasting for 24 or 48 hours in duration. Using the dog as a large mammalian model, PAC-1 can be safely administered as an intravenous CRI while achieving predicted in vitro cytotoxic concentrations.

This study evaluated the subchronic toxicity of StemEnhance™, an extract of the blue-green alga Aphanizomenon flos-aquae that is used as a health supplement. Groups of 12 rats of each sex were given either 5% glycerin in water (control) or 200 mg/kg of StemEnhance prepared in 5% glycerin in water for 90 days by oral gavage. The administration of StemEnhance had no effect on behavior, food and water intake, growth, or survival. Values at the end of dosing and observation periods did not reveal differences between treated and control groups for hematology and clinical chemistry. There were no significant differences in the gross and histopathology of the reproductive organs in either males or females. Sperm motility parameters were similar for control and treated males. Our results show that StemEnhanceat doses ~7 times the maximum label-recommended daily dose did not produce adverse effects in Wistar rats after subchronic treatment.