Establishment of a spontaneous ventilation anesthesia model for beagle dogs

While spontaneous ventilation (SV) anesthesia is in use for clinical patients, there is still little systematic experimental research into its basic aspects. The rabbit SV model that we established previously has some limitations including the model being too small, differences in anesthetic drugs and anesthesia procedures, so we set out to establish an SV anesthesia model for beagle dogs.•Single lumen tracheal intubation was performed on beagles connecting a ventilator, and the anesthetic dosage was adjusted for spontaneous ventilation before surgery.•5 mL of 1 % lidocaine was applied as a local infiltration anesthesia at the surgical incision.•After thoracotomy, 5 mL of 1% lidocaine was sprayed onto the surface of the lungs and a T3-T7 intercostal nerve block (1:1 2 % lidocaine:0.75 % ropivacaine) was performed.

A novel magnetic compression technique for establishment of a vesicovaginal fistula model in Beagle dogs

Vesicovaginal fistula lacks a standard, established animal model, making surgical innovations for this condition challenging. Herein, we aimed to non-surgically establish vesicovaginal fistula using the magnetic compression technique, and the feasibility of this method was explored using eight female Beagle dogs as model animals. In these dogs, cylindrical daughter and parent magnets were implanted into the bladder and vagina, respectively, after anesthesia, and the positions of these magnets were adjusted under X-ray supervision to make them attract each other, thus forming the structure of daughter magnet-bladder wall-vaginal wall-parent magnet. Operation time and collateral damage were recorded. The experimental animals were euthanized 2 weeks postoperatively, and the vesicovaginal fistula gross specimens were obtained. The size of the fistula was measured. Vesicovaginal fistula was observed by naked eye and under a light microscope. Magnet placement was successful in all dogs, and remained in the established position for the reminder of the experiment. The average operation time was 14.38 min ± 1.66 min (range, 12-17 min). The dogs were generally in good condition postoperatively and were voiding normally, with no complications like bleeding and urine retention. The magnets were removed from the vagina after euthanasia. The vesicovaginal fistula was successfully established according to gross observation, and the fistula diameters were 4.50-6.24 mm. Histological observation revealed that the bladder mucosa and vaginal mucosa were in close contact on the internal surface of the fistula. Taken together, magnetic compression technique is a simple and feasible method to establish an animal model of vesicovaginal fistula using Beagle dogs. This model can help clinicians study new surgical techniques and practice innovative approaches for treating vesicovaginal fistula.

Transcript abundance of hepatic drug-metabolizing enzymes in two dog breeds compared with 14 species including humans

Drug-metabolizing enzymes are important in drug development and therapy, but have not been fully identified and characterized in many species, lines, and breeds. Liver transcriptomic data were analyzed for phase I cytochromes P450, flavin-containing monooxygenases, and carboxylesterases and phase II UDP-glucuronosyltransferases, sulfotransferases, and glutathione S-transferases. Comparisons with a variety of species (humans, rhesus macaques, African green monkeys, baboons, common marmosets, cattle, sheep, pigs, cats, dogs, rabbits, tree shrews, rats, mice, and chickens) revealed both general similarities and differences in the transcript abundances of drug-metabolizing enzymes. Similarly, Beagle and Shiba dogs were examined by next-generation sequencing (RNA-seq). Consequently, no substantial differences in transcript abundance were noted in different breeds of pigs and dogs and in different lines of mice and rats. Therefore, the expression profiles of hepatic drug-metabolizing enzyme transcripts appear to be similar in Shiba and Beagle dogs and pig breeds and the rat and mouse lines analyzed, although some differences were found in other species.

Biocompatibility of dental implants coated with hydroxyapatite using pulsed Er:YAG laser deposition

We aimed to improve the biocompatibility and osteoinductive potential of Ti implants using a simulated intraoral hydroxyapatite (HAp) coating. We devised a novel surface treatment for aggressive induction of osteoblast adhesion and bone regeneration on the implant surface. A thin α-tricalcium phosphate (α-TCP) film was deposited on the implant surface using a pulsed Er:YAG laser. The coating was converted to HAp through artificial saliva immersion, which was confirmed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). SEM showed needle-like HAp crystals on the Ti disks and sandblasted implant surfaces after immersion in artificial saliva for 96 h. Microcomputed tomography and histological evaluation 4 and 8 weeks after implantation into beagle dog mandibles showed that the HAp-coated implant was biocompatible and exhibited superior osteoinduction compared to that of sandblasted implants. Coating the implant surface with HAp using an Er:YAG laser has potential as a new method of the implant-surface debridement.

Comparison of methods for the effective evaluation of the energy content of poultry by-product meal for beagles

The objectives of this study were to compare the energy values of poultry by-product meal (PBM) as feed for adult beagle dogs using the direct, difference, and regression methods to examine dogs' nitrogen metabolism, energy utilization, gaseous metabolism, and body health. Five groups of six 12-month-old female beagles with an average body weight of 9.67 ± 0.52 kg were tested in a 5×6 incomplete Latin square design, with six repetitions in each group. Five experimental diets were tested consisting of 100% PBM; three substitution diets containing either 15%, 30%, or 45% PBM (termed 15PBM, 30PBM, and 45PBM, respectively); and a basal diet (included 6.90% PBM). Each experimental period lasted for 10 days, comprising 4 days of dietary acclimation followed by 6 days of testing (including 3 day feeding period and 3 day fasting period), during which the heat production (HP) was determined and feces and urine were collected. Results showed that, in the feeding state, the nitrogen intake, urinary nitrogen, apparent nitrogen digestibility, retained nitrogen, and heat production (HP) increased significantly (P < 0.05) as the PBM level increased. The net protein utilization, biological value of protein, and total apparent digestibility of amino acids did not differ between the 30PBM and 45PBM diets (P > 0.05). The O2 consumption and CO2 production of beagles during the fasting period were not influenced by the PBM level (P > 0.05). The digestible energy and metabolizable energy values of the PBM estimated by the regression method were 20.16 MJ/kg and 18.18 MJ/kg dry matter (DM), respectively, and did not differ from those determined by the direct method (P > 0.05). The fecal dry matter percentages and fecal PBM scores were significantly higher in the PBM diet than in the difference method groups (P < 0.05). The direct method group had a significantly higher fecal score (4.63) than the other groups (P < 0.05), The fecal score of the 45PBM diet (3.50) was significantly higher than the 30PBM diet (2.90) (P < 0.05). In summary, the direct method and difference method of determining the effective energy value of PBM for beagles, produce significantly different results. Under the conditions of this test, the best proportion of PBM in beagle feed for optimum energy provision is 30%.

Differential miRNA expression profiles in the bone marrow of Beagle dogs at different stages of Toxocara canis infection

BACKGROUND

Toxocara canis is distributed worldwide, posing a serious threat to both human and dog health; however, the pathogenesis of T. canis infection in dogs remains unclear. In this study, the changes in microRNA (miRNA) expression profiles in the bone marrow of Beagle dogs were investigated by RNA-seq and bioinformatics analysis.

RESULTS

Thirty-nine differentially expressed (DE) miRNAs (DEmiRNAs) were identified in this study. Among these, four DEmiRNAs were identified at 24 h post-infection (hpi) and all were up-regulated; eight DEmiRNAs were identified with two up-regulated miRNAs and six down-regulated miRNAs at 96 hpi; 27 DEmiRNAs were identified with 13 up-regulated miRNAs and 14 down-regulated miRNAs at 36 days post-infection (dpi). Among these DEmiRNAs, cfa-miR-193b participates in the immune response by regulating the target gene cd22 at 24 hpi. The novel_328 could participate in the inflammatory and immune responses through regulating the target genes tgfb1 and tespa1, enhancing the immune response of the host and inhibiting the infection of T. canis at 96 hpi. In addition, cfa-miR-331 and novel_129 were associated with immune response and self-protection mechanisms at 36 dpi. 20 pathways were significantly enriched by KEGG pathway analysis, most of which were related to inflammatory response, immune response and cell differentiation, such as Cell adhesion molecules (CAMs), ECM-receptor interaction and Focal adhesion.

CONCLUSIONS

These findings suggested that miRNAs of Beagle dog bone marrow play important roles in the pathogenesis of T. canis infection in dogs and provided useful resources to better understand the interaction between T. canis and the hosts.

Lung Lipidomic Alterations in Beagle Dogs Infected with Toxocara canis

Toxocariasis, mainly caused by Toxocara canis, and to a lesser extent, Toxocara cati, is a neglected parasitic zoonosis. The mechanisms that underlie the changes in lipid metabolism of T. canis infection in Beagle dogs' lungs remain unclear. Lipidomics is a rapidly emerging approach that enables the global profiling of lipid composition by mass spectrometry. In this study, we performed a non-targeted lipidomic analysis of the lungs of Beagle dogs infected with the roundworm T. canis using liquid chromatography-tandem mass spectrometry (LC-MS/MS). A total of 1197 lipid species were identified, of which 63, 88, and 157 lipid species were significantly altered at 24 h post-infection (hpi), 96 hpi, and 36 days post-infection (dpi), respectively. This global lipidomic profiling identified infection-specific lipid signatures for lung toxocariasis, and represented a comprehensive comparison between the lipid composition of dogs' lungs in the presence and absence of T. canis infection. The potential roles of the identified lipid species in the pathogenesis of T. canis are discussed, which has important implications for better understanding the interaction mechanism between T. canis and the host lung.

Differential Spleen miRNA Expression Profile of Beagle Dogs Infected with Toxocara canis

Toxocara canis is an unnoticed zoonotic helminth that causes severe disease in animals and humans. The spleen has a wide range of immunological functions in protecting the host against infection by many pathogens, but the function of the spleen in T. canis infection is still to be clarified, especially for the role of spleen microRNAs (miRNAs). In this study, deep sequencing of spleen RNA samples of 18 Beagle puppies was conducted to uncover the miRNAs expression profiling at 24 h post-infection (hpi), 96 hpi, and 36 days post infection (dpi). A total of 20, 34, and 19 differentially expressed miRNAs (DEmiRNAs) were identified at 24 hpi, 96 hpi, and 36 dpi, respectively. These DEmiRNAs (e.g., cfa-miR-206, cfa-miR-331, and cfa-miR-339) could play critical roles in Beagle puppies against T. canis infection, such as influencing inflammatory and immune-related cells and cytokines, by regulating target genes that are tightly associated with host immune function and enriched in immune response and immune pathways based on GO annotation and KEGG enrichment analysis. The current study discovered marked alterations of spleen miRNAs after T. canis infection, with potential effects on the pathogenesis of toxocariasis.

RNA sequencing reveals dynamic expression of spleen lncRNAs and mRNAs in Beagle dogs infected by Toxocara canis

BACKGROUND

Toxocara canis is a cosmopolitan parasite with a significant adverse impact on the health of humans and animals. The spleen is a major immune organ that plays essential roles in protecting the host against various infections. However, its role in T. canis infection has not received much attention.

METHODS

We performed sequencing-based transcriptome profiling of long noncoding RNA (lncRNA) and messenger RNA (mRNA) expression in the spleen of Beagle puppies at 24 h post-infection (hpi), 96 hpi and 36 days post-infection (dpi). Deep sequencing of RNAs isolated from the spleen of six puppies (three infected and three control) at each time point after infection was conducted.

RESULTS

Our analysis revealed 614 differentially expressed (DE) lncRNAs and 262 DEmRNAs at 24 hpi; 726 DElncRNAs and 878 DEmRNAs at 96 hpi; and 686 DElncRNAs and 504 DEmRNAs at 36 dpi. Of those, 35 DElncRNA transcripts and 11 DEmRNAs were detected at all three time points post-infection. Many DE genes were enriched in immune response, such as ifit1, ifit2 and rorc. Kyoto Encyclopedia of Genes and Genomes enrichment analysis revealed that some genes (e.g. prkx and tnfrsf11a) were involved in the T cell receptor signaling pathway, calcium signaling pathway, Ras signaling pathway and NF-κB signaling pathway.

CONCLUSIONS

The findings of this study show marked alterations in the expression profiles of spleen lncRNAs and mRNAs, with possible implications in the pathophysiology of toxocariasis.

A Technical Guide to Sampling the Beagle Dog Nervous System for General Toxicity and Neurotoxicity Studies

Beagle dogs are a key nonrodent species in nonclinical safety evaluation of new biomedical products. The Society of Toxicologic Pathology (STP) has published "best practices" recommendations for nervous system sampling in nonrodents during general toxicity studies (Toxicol Pathol 41[7]: 1028-1048, 2013), but their adaptation to the Beagle dog has not been defined specifically. Here we provide 2 trimming schemes suitable for evaluating the unique neuroanatomic features of the dog brain in nonclinical toxicity studies. The first scheme is intended for general toxicity studies (Tier 1) to screen test articles with unknown or no anticipated neurotoxic potential; this plan using at least 7 coronal hemisections matches the STP "best practices" recommendations. The second trimming scheme for neurotoxicity studies (Tier 2) uses up to 14 coronal levels to investigate test articles where the brain is a suspected or known target organ. Collection of spinal cord, ganglia (somatic and autonomic), and nerves for dogs during nonclinical studies should follow published STP "best practices" recommendations for sampling the central (Toxicol Pathol 41[7]: 1028-1048, 2013) and peripheral (Toxicol Pathol 46[4]: 372-402, 2018) nervous systems. This technical guide also demonstrates the locations and approaches to collecting uncommonly sampled peripheral nervous system sites.

Nonclinical cardiovascular safety assessment of thioridazine: Impact of autonomic tone, body temperature, and choice of species

Pending updates to ICH S7B/E14 guidelines may enable the substitution of human TQT studies with concomitant negative hERG and non-rodent CV studies. This retrospective analysis compared the effects of thioridazine (THD) (5-20 mg/kg) on heart rate (HR), blood pressure (BP), body temperature (Tc), and QT in the dog (n = 6), cynomolgus monkey (n = 4), and Goettingen minipig (n = 4) with data from previously completed studies employing crossover designs. As QT measurements are confounded by HR and Tc changes, QT effects were individually corrected for changes in HR (QTca) and Tc (QTcaT). THD-induced hemodynamic changes seen in humans were most accurately reflected in the monkey and, to a lesser extent, the dog, but not in the minipig. The minipig was most sensitive to THD QTc effects. When QTca was adjusted for THD-associated Tc decreases in minipigs and monkeys, the minipig revealed a lessened but pronounced QTcaT increase (48 ms). In the monkey, a persistent QTca increase was reduced to only a transient (0.5-3 h) QTcaT increase (20 ms). The dog's lack of THD QTca effects triggered co-administration of atenolol (AT) to attenuate THD-induced HR increases in the dog and monkey. THD + AT revealed peak QTcaT increases of 32 ms in the dog and 40 ms in the monkey, suggesting potential autonomic nervous system (ANS) interference in detecting repolarization changes. These results highlight critical species-specific differences in the outcome of parallel safety investigations. Species selection for nonclinical safety studies should consider the potential impact of Tc and ANS effects to avoid false-negative or overly positive outcomes.

Novel dapagliflozin di-L-proline cocrystal-loaded tablet: Preparation, physicochemical characterization, and pharmacokinetics in beagle dogs and mini-pigs

Dapagliflozin base and a commercial dapagliflozin propanediol hydrate cocrystal (DPF-PDHC) were highly hygroscopic and thermally unstable. In this study, to address this limitation, we prepared a novel dapagliflozin di-L-proline cocrystal (DPF-LPC) and evaluated its physicochemical characterization compared with DPF-PDHC. After the preparation of the DPF-LPC-loaded tablet, its dissolution, stability and bioequivalence in beagle dogs and mini-pigs were assessed. DPF-LPC was well prepared with a dapagliflozin base and L-proline in a molar ratio of 1:2. Similar to DPF-PDHC, DPF-LPC was highly lipophilic and crystalline in nature. However, these two cocrystals exhibited different melting points and crystalline structures, indicating their different cocrystal forms. Moreover, DPF-LPC exhibited less hygroscopicity and lower water content than DPF-PDHC. The DPF-LPC-loaded tablet composed of DPF-LPC, Comprecel M102, lactose monohydrate, crospovidone, magnesium stearate, and Opadry (coating) at a weight ratio of 15.6:104.4:100.0:8.0:2.0:7.0, was dissolution-equivalent to the commercial tablet. Moreover, it provided lower impurities than the commercial tablet, indicating its better stability. In the two animals, there were no significant differences in the plasma concentrations, AUC, C_max, and T_max values, suggesting that they were bioequivalent. Therefore, the novel DPF-LPC-loaded tablet with excellent stability and bioequivalence may be used as a potential alternative to the commercial DPF-PDHC-loaded tablet.

Bioanalysis of lanreotide in dog plasma using liquid chromatography-tandem mass spectrometry and its application in a pharmacokinetic study of beagle dogs after single subcutaneous injection

Lanreotide is similar to a naturally occurring hormone, somatostatin; thus, it may be used to treat acromegaly or metastatic gastroenteropancreatic neuroendocrine tumours. Here, a bioanalytical method coupling ultra-performance liquid chromatography with tandem mass spectrometry to quantify lanreotide and an internal standard (IS) was developed and validated in dog plasma. The plasma samples were extracted using typical protein precipitation processes. The analyte and internal standard were separated on Phenomenex Kinetex® C18 with 0.1% formic acid and acetonitrile in the mobile phase at a flow rate of 0.4 mL/min. The fragmentation of precursor ions to product ions was optimized at m/z 548.8 → 170.0 for lanreotide [M + 2H]²⁺ and 472.2 → 436.2 for IS [M + H]⁺. The peak retention times of lanreotide and IS were 1.09 min and 1.22 min, respectively. The calibration curve samples in dog plasma ranged from 0.3 to 1000 ng/mL and showed good linearity, with a correlation coefficient of r²=0.9996. The lower limit of quantitation was 0.3 ng/mL. The intra- and inter-day precision (relative standard deviation) values for each quality control level were < 9.7 % and < 9.3 %, respectively; intra- and inter-day accuracy were < 109.3% and < 110.4%, respectively. Lanreotide in dog plasma was stable in various conditions. The maximum plasma concentration of lanreotide in male beagle dogs after subcutaneous injection of Somatuline® (lanreotide) Autogel 120 mg was 88.1 ng/mL. The half-life (T_1/2) of lanreotide in beagle dogs was long, approximately 198.6 h; the area under the plasma-concentration curve from 0 to 840 h (day 35) was 6,995 ng⋅h/mL. This novel quantification method using UPLC-MS/MS was successfully applied to the pharmacokinetic analysis of lanreotide in dog plasma. The results will assist future studies of drug formulation and repurposing.

Evaluation of chronic toxicity of cyclocreatine in beagle dogs after oral gavage administration for up to 23 weeks

Cyclocreatine (LUM-001) was evaluated for chronic toxicity (23 weeks) in beagle dogs to support clinical development in patients with creatine transporter deficiency (CTD) disorder. Deionized water (vehicle control) or cyclocreatine was administered by oral gavage twice daily (12 ± 1 h apart) at 20, 40 and 75 mg/kg/dose followed by a recovery period. Due to severe toxicity, the study was terminated earlier than the planned 39 weeks of dosing. Animals in the 20, 40 and 75 mg/kg/dose groups completed 160, 106, and 55 days of dosing, respectively, followed by 30, 55 and 106 days of a recovery period, respectively. Three (25%), 7 (58%), and 7 (58%) animals were euthanized and/or found dead in the 40, 80, and 150 mg/kg/day dose groups, respectively. Clinical signs observed were inappetence, frequent emesis, stool abnormalities, weight loss, lethargy and respiratory distress. Histopathological evaluation revealed congestion, edema, cellular infiltration, fibrin, and/or hemorrhage in the lungs of all dose groups. Additionally, animals in all cyclocreatine treatment groups had perinuclear cytoplasmic vacuoles in the heart, kidneys, skeletal and smooth muscles. After the recovery period, the vacuoles were still observed in the cardiac and renal tissues. Cyclocreatine was absorbed rapidly with mean Tmax within 1 to 2 h and half-life ranged between 2.17 and 2.79 h on Day 1, however, on the final day of dosing, it ranged between 5.80 and 8.77 h (males) and 10.3 to 13.1 h (females). To conclude, in this study the lungs, kidneys, heart, skeletal and smooth muscles were identified as the target organs of cyclocreatine toxicity in beagle dogs.

Toxocara canis Infection Alters lncRNA and mRNA Expression Profiles of Dog Bone Marrow

Bone marrow is the main hematopoietic organ that produces red blood cells, granulocytes, monocyte/macrophages, megakaryocytes, lymphocytes, and myeloid dendritic cells. Many of these cells play roles in the pathogenesis of Toxocara canis infection, and understanding how infection alters the dynamics of transcription regulation in bone marrow is therefore critical for deciphering the global changes in the dog transcriptional signatures during T. canis infection. In this study, long non-coding RNA (lncRNA) and messenger RNA (mRNA) expression profiles in the bone marrow of Beagle dogs infected with T. canis were determined at 12 h post-infection (hpi), 24 hpi, 96 hpi, and 36 days post-infection (dpi). RNA-sequencing and bioinformatics analysis identified 1,098, 984, 1,120, and 1,305 differentially expressed lncRNAs (DElncRNAs), and 196, 253, 223, and 328 differentially expressed mRNAs (DEmRNAs) at 12 h, 24 h, 96 h, and 36 days after infection, respectively. We also identified 29, 36, 38, and 68 DEmRNAs potentially cis-regulated by 44, 44, 51, and 80 DElncRNAs at 12 hpi, 24 hpi, 96 hpi, and 36 dpi, respectively. To validate the sequencing findings, qRT-PCR was performed on 10 randomly selected transcripts. Many altered genes were involved in the differentiation of bone marrow cells. GO of DElncRNAs and GO and KEGG pathway analyses of DEmRNAs revealed alterations in several signaling pathways, including pathways involved in energy metabolism, amino acid biosynthesis and metabolism, Wnt signaling pathway, Huntington's disease, HIF-1 signaling pathway, cGMP–PKG signaling pathway, dilated cardiomyopathy, and adrenergic signaling in cardiomyocytes. These findings revealed that bone marrow of T. canis-infected dogs exhibits distinct lncRNA and mRNA expression patterns compared to healthy control dogs. Our data provide novel insights into T. canis interaction with the definitive host and shed light on the significance of the non-coding portion of the dog genome in the pathogenesis of toxocariasis.

Urinary microRNAs miR-15b and miR-30a as novel noninvasive biomarkers for gentamicin-induced acute kidney injury

MicroRNAs serve as potential biomarkers in various pathological models, and are stable and detectable in biofluids. We investigated the urinary microRNA expression profile in a gentamicin-induced acute kidney injury canine model using RNA sequencing. A total of 234 differentially expressed microRNAs were screened after 12 consecutive days of gentamicin administration (P < 0.05). Six candidate microRNAs (miR-15b, -15b-3p, -16, -30a, -30a-3p, and -30c-2-3p) were selected according to a set criterion, and validated by real-time quantitative PCR. The diagnostic values of these six candidate microRNAs were better than the traditional serum biomarkers (all P < 0.05). Further, using receiver operating characteristic curve analysis, we found that miR-15b and -15b-3p were superior to urinary kidney injury molecule-1 (both P < 0.05). Moreover, miR-15b and -30a levels in the urine samples significantly correlated with their respective levels in the kidney tissue samples (r=0.512 and 0.505, respectively, both P < 0.05). Our data concluded that miR-15b and -30a may be promising biomarkers for renal toxicity.

Proteomic alterations in the plasma of Beagle dogs induced by Toxocara canis infection

Toxocara canis causes ocular larva migrans and visceral larva migrans in humans. Knowledge about the molecular mechanism of T. canis-hosts interaction is limited. The proteomic alterations in the plasma of Beagle dogs induced by T. canis infection were studied by the quantitative mass spectrometry-based data-independent acquisition (DIA). 418, 414 and 411 plasma proteins were identified at 24 h post-infection (hpi), 96 hpi and 36 days post-infection (dpi), including 6, 5 and 23 proteins with differential abundance, respectively. At 24 hpi, the altered proteins, retinoic acid receptor responder protein 2 (RARRES2), WD repeat-containing protein 1 (WDR1), moesin and filamin-A, may participate in pro-inflammatory reaction or promote larvae migration. At 96 hpi, the altered protein C and fibroleukin may maintain the stability of the coagulation system to protect the lung. At 36 dpi, the alterations of C-reactive protein (CRP), ficolin (FCN), complement factor H-related protein 5 (CFHR5) and other complements can affect the three traditional complement system, including the classic pathway, lectin pathway and alternative pathway. These proteins may play important roles in the interaction between T. canis and its definitive hosts. Further study on these altered proteins triggered by T. canis infection may discovery novel therapeutic or diagnostic targets for toxocariasis. SIGNIFICANCE OF THE STUDY: Toxocara canis is one of the globally distributed soil-transmitted helminths, which causes ocular larva migrans and visceral larva migrans in humans and a wide range of warm-blooded animals. T. canis adapts to different microenvironments by resisting and adjusting various biological processes of the hosts. Knowledge about the molecular mechanism of T. canis-hosts interaction is limited. Plasma proteins are good marker for monitoring the occurrence and development of diseases. The proteomic alterations in the plasma of Beagle dogs induced by T. canis infection were studied by the quantitative mass spectrometry-based data-independent acquisition (DIA) in this study. A total of 418, 414 and 411 plasma proteins were identified at 24 h post-infection (hpi), 96 hpi and 36 days post-infection, respectively. Ten protein with differential abundances were validated by using parallel reaction monitoring (PRM). Collectively, our deep proteomic analysis of plasma revealed that proteins alterations were affected by disease development, and proteomic analysis is an ideal method for quantifying changes in circulating factors on a global scale in response to pathophysiological perturbations such as T. canis infection.

Performance of two bone substitutes of novel cotton-like β-TCP/PDLGA and granular β-TCP on bone regeneration in the femoral bone defect of the Beagle dogs

This study aimed to clarify whether novel cotton-like composite made of β-tricalcium phosphate (β-TCP) and poly(Dl-lactide-co-glycolide) (PDLGA) has a different effect on in vivo bone regeneration after bone defect than that of granular β-TCP. Five male Beagle dogs served as subjects. Cortical and medullary bone defect as non-through holes were made at the diaphysis of the bilateral femurs. One side was implanted with β-TCP/PDLGA (β-TCP/PDLGA group) and the other side was implanted with granular β-TCP (β-TCP group). At 4 weeks after implantation, we found no significant differences in the percentages of newly formed bone area and fibrous tissue area in the bone defect between the two groups. The β-TCP/PDLGA group showed more uniform filling on the surface and earlier disappearance of the material in the medullary region, and there were fewer inflammatory cells and osteoclasts in the bone defect in the β-TCP/PDLGA group. In conclusion, β-TCP/PDLGA performs better at filling the bone defect uniformly and disappears earlier at the cortical and medullary regions while causing less inflammation and bone resorption. Although bone formation activity of the β-TCP/PDLGA group in the cortical region was lower, the newly formed bone volume in bone defect of the β-TCP/PDLGA group was equal to that of the β-TCP group.

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Novel cotton-like composite made of β-TCP/PDLGA was compared with granular β-TCP.

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Cotton-like β-TCP/PDLGA performed better at filling the bone defect uniformly.

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Cotton-like β-TCP/PDLGA disappeared earlier at the implanted bone regions.

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β-TCP/PDLGA caused less inflammation and bone resorption in the bone defect.

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The newly formed bone volume in bone defect was equal between the two materials.

Global profiling of lncRNAs-miRNAs-mRNAs reveals differential expression of coding genes and non-coding RNAs in the lung of beagle dogs at different stages of Toxocara canis infection

The roundworm Toxocara canis causes toxocariasis in dogs and larval migrans in humans. Better understanding of the lung response to T. canis infection could explain why T. canis must migrate to and undergoes part of its development inside the lung of the definitive host. In this study, we profiled the expression patterns of long non-coding RNAs (lncRNAs), microRNAs (miRNAs), and mRNAs in the lungs of Beagle dogs infected by T. canis, using high throughput RNA sequencing. At 24 h p.i., 1,012 lncRNAs, 393 mRNAs and 10 miRNAs were differentially expressed (DE). We also identified 883 DElncRNAs, 264 DEmRNAs and 20 DEmiRNAs at 96 h p.i., and 996 DElncRNAs, 342 DEmRNAs and eight DEmiRNAs at 36 days p.i., between infected and control dogs. Significant changes in the levels of expression of transcripts related to immune response and inflammation were associated with the antiparasitic response of the lung to T. canis. The remarkable increase in the expression of scgb1a1 at all time points after infection suggests the need for consistent moderation of the excessive inflammatory response. Also, upregulation of foxj1 at 24 h p.i., and downregulation of IL-1β and IL-21 at 96 h p.i., suggest an attenuation of the humoral immunity of infected dogs. These results indicate that T. canis pathogenesis in the lung is mediated through contributions from both pro-inflammatory and anti-inflammatory mechanisms. Competing endogenous RNA (ceRNA) network analysis revealed significant interactions between DElncRNAs, DEmiRNAs and DEmRNAs, and improved our understanding of the ceRNA regulatory mechanisms in the context of T. canis infection. These data provide comprehensive understanding of the regulatory networks that govern the lung response to T. canis infection and reveal new mechanistic insights into the interaction between the host and parasite during the course of T. canis infection in the canine.

in Beagle Dogs

Alstonia scholaris (L.) R. Br., an evergreen tropical plant rich in indole alkaloids with significant physiological activity, is traditionally used to treat respiratory diseases in China. This study was conducted to establish the toxicity profile of the alkaloid extract (TA) of A. scholaris leaves in non-rodents. After oral administration of a single dose (4 g/kg.bw), a number of transient symptoms, such as unsteady gait, drooling, emesis, and reddening of peri-oral mucosa, were observed, but no treatment-related mortality. A sub-chronic toxicity study with a range of doses of TA (20, 60 and 120 mg/kg.bw) was conducted for a 13-week treatment period, followed by 4-week recovery observation. Except for emesis and drooling in majority of animals in 120 mg/kg.bw treatment group, no clinical changes were observed in TA-treated animals. Data from electrocardiography, bone marrow, urine, fecal, hematology and clinical chemistry analyses were comparable between TA-treated and control animals. No significant differences in the relative organ weights and histopathological characteristics were evident between the TA-treated and control groups. Accordingly, the non-observed-adverse-effect-level (NOAEL) of TA was established as 120 mg/kg.bw. Our results add further knowledge to the safety database for indole alkaloid extracts from A. scholaris with potential utility as novel drug candidates.

Safety reassessment of cinobufotalin injection: new findings into cardiotoxicity

Cinobufotalin injection, a traditional Chinese medicine preparation, successfully used for several years, might induce cardiotoxicity. The aim of the study was to evaluate the cardiotoxicity of cinobufotalin injection and the cardiotoxicity-preventive effect of sodium phenytoin in vivo. According to the 4 × 4 Latin square design, four Beagle dogs were allocated into four dose levels of 0, 0.3, 1, and 3 g/kg in treatment phases I-IV (cinobufotalin injection) and 3 g/kg in treatment phase V (cardiotoxicity antidote). The following parameters and endpoints were assessed: clinical observations, body weight, indicators of myocardial injury, and electrocardiogram (ECG) parameters. The cinobufotalin injection-related changes were observed in clinical observations (rapid breathing pattern), indicators of myocardial injury (increased cardiac troponin I, creatine kinase isoenzymes, and aspartate aminotransferase), and ECG graphics (arrhythmia) at 3 g/kg concentration in treatment phases I-IV. The cardiotoxicity of cinobufotalin injection was attenuated by sodium phenytoin in treatment phase V. The results confirmed the cardiotoxicity of cinobufotalin injection, and they might bring information about the appropriate monitoring time points and cardiotoxicity parameters in clinical practices and shed light on the treatment of cardiovascular adverse reactions.

Spontaneous Axonal Dystrophy in the Brain and Spinal Cord in Naïve Beagle Dogs

Axonal dystrophy (AD) is a common age-related neurohistological finding in vertebrates that can be congenital or induced by xenobiotics, vitamin E deficiency, or trauma/compression. To understand the incidence and location of AD as a background finding in Beagle dogs used in routine toxicity studies, we examined central nervous system (CNS) and selected peripheral nervous system (PNS) tissues in twenty 18- to 24-month-old and ten 4- to 5-year-old control males and females. Both sexes were equally affected. The cuneate, gracile, and cochlear nuclei and the cerebellar white matter (rostral vermis) were the most common locations for AD. Incidence of AD increased with age in the cuneate nucleus, cerebellar white matter (rostral vermis), trigeminal nuclei/tracts, and lumbar spinal cord. Axonal dystrophy in the CNS was not accompanied by neuronal degeneration/necrosis, nerve fiber degeneration, and/or glial reaction. Axonal dystrophy was not observed in the PNS (sciatic nerve, vagus nerve branches, or gastrointestinal mural autonomic plexuses).

Development of a novel and quick UPLC-MS/MS method for the pharmacokinetic analysis of duvelisib in beagle dogs

Duvelisib, a new oral phosphoinositide-3-kinase (PI3K)-δ and PI3K-γ inhibitor, was recently approved in the USA as the therapeutic drug for patients with the diseases of relapsed or refractory chronic lymphocytic leukemia (CLL) and small lymphocytic lymphoma (SLL). In the present study of our research, a quick and simple bioanalytical method based on ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) technique was fully explored and established for the quantification of plasma duvelisib concentrations from beagle dog in which gilteritinib was used as the internal standard (IS). After a simple and quick protein precipitation treated with acetonitrile, the chromatographic separation of the analyte was carried out on an Acquity BEH C18 column (2.1 mm × 50 mm, 1.7 μm) conducted in a gradient elution procedure where acetonitrile (solvent A) and 0.1 % formic acid in water (solvent B) consisted as the mobile phase. The measurements of the analyte and IS were explored using a XEVO TQS triple quadrupole tandem mass spectrometer, which was comprised with electrospray ionization (ESI) source in positive ion mode. Selected reaction monitoring (SRM) mode was employed to detect the parent-to-daughter ion transitions as follows: m/z 416.88 → 281.88 for duvelisib, and m/z 553.09 → 436.01 for IS, respectively. The assay was successfully established in the calibration range from 0.5 to 3000 ng/mL for duvelisib, where the lower limit of quantification (LLOQ) was set at 0.5 ng/mL. The precisions of intra-day and inter-day for duvelisib were all below 12.6 %, and the accuracies were from -2.5% to 14.1%. Both matrix effect and mean recovery of the analyte and IS were all acceptable, and the analyte was stable during the assay and storage in dog plasma samples. The novel established bioanalytical method based on UPLC-MS/MS technique was effectively employed to the investigation of the pharmacokinetic profile of duvelisib in beagle dogs following a 1.34 mg/kg single dose of oral administration.

Unusual Incidence and Location of Renaut Bodies in Beagle Dogs in a Nonclinical Study

We identified the presence of Renaut bodies in an unusual location in Beagle dogs on a 3-month nonclinical toxicity study. These peculiar structures are commonly reported as a background finding in the sciatic nerve of dogs. In our study, however, they were also observed in autonomic nerves surrounding the adrenal gland, a location in which they have not been reported before. The incidence in both locations were 8 of 32 Beagle dogs in the sciatic nerve and 6 of 40 Beagle dogs around the adrenal gland in the dosing and/or recovery phases of the study.

Genotoxicity and subchronic toxicological study of a novel ginsenoside derivative 25-OCH3-PPD in beagle dogs

Background

Ginsenosides have been widely used clinically for many years and were regarded as very safe. However, a few researches on the toxicities of these kinds of agents showed that some ginsenosides may have side-effect on the rats or dogs. So it is extremely necessary to further clarify the potential toxicity of ginsenosides. This study was carried out to investigate long-term toxicity and genotoxicity of 25-methoxydammarane-3, 12, 20-triol (25-OCH₃-PPD), a new derivative of ginsenoside, in beagle dogs.

Methods

Twenty-four beagle dogs were divided randomly into four treatment groups and repeatedly orally administered with 25-OCH₃-PPD capsule at 60, 120, and 240 mg/kg/day for 91 consecutive days. Ames, micronucleus, and chromosomal aberration tests were established to analyze the possible genotoxicity of 25-OCH₃-PPD.

Results

There was no 25-OCH₃-PPD–induced systemic toxicity in beagle dogs at any doses. The level of 25-OCH₃-PPD at which no adverse effects were observed was found to be 240 mg/kg/day. The result of Ames test showed that there was no significant increase in the number of revertant colonies of 25-OCH₃-PPD administrated groups compared to the vehicle control group. There were also no significant differences between 25-OCH₃-PPD administrated groups at all dose levels and negative group in the micronucleus test and chromosomal aberration assay.

Conclusion

The highest dose level of 25-OCH₃-PPD at which no adverse effects were observed was found to be 240 mg/kg per day, and it is not a genotoxic agent either in somatic cells or germs cells. 25-OCH₃-PPD is an extremely safe candidate compound for antitumor treatment.

A novel biodegradable occluder for the closure of ventricular septal defects: immediate and medium-term results in a canine model

OBJECTIVES

The feasibility of an Amplatzer septal occluder closure of ventricular septal defects (VSDs) under echocardiographic guidance has already been proven. However, the technique is not used routinely owing to high-rate atrioventricular blocks and the non-absorbability of the occluder. Here, we aimed to evaluate the safety, biocompatibility and effectiveness of a new biodegradable occluder.

METHODS

A total of 18 adult beagle dogs [mean body weight 8.85 kg (range 8.10-10.40 kg)] were enrolled in our study from March 2015 to July 2018. VSD animal models were prepared by thoracic intervention, and the new bioabsorbable occluder was implanted under the guidance of transthoracic echocardiography. Laboratory examinations, transthoracic echocardiography and electrocardiography were performed after surgery, and pathological samples from dogs were obtained after euthanasia and examined in the 1st, 3rd, 6th, 9th, 12th and 24th months to evaluate the safety, biocompatibility and effectiveness of the biodegradable occluder.

RESULTS

All the dogs received successful implantations of the biodegradable occluder and survived, showing no follow-up-related complications (such as dislocation, arrhythmia and recanalization). Biochemical tests showed no significant abnormalities or differences, except for an increase in white blood cells and C-reactive proteins on the day after the operation. Histopathological examinations revealed that the bioabsorbable occluders were biocompatible, while immunohistochemical evaluations and electron microscopy showed endothelial cells growing on the occluder surface.

CONCLUSIONS

The effective occlusion of VSD, good biocompatibility, rapid endothelialization and lack of complications shown by the biodegradable occluder in this study suggest that the device meets acceptable clinical safety and has potential application prospects.

Serum metabolomic alterations in Beagle dogs experimentally infected with Toxocara canis

Background

Toxocara canis, a globally distributed roundworm, can cause debilitating disease in dogs and humans; however, little is known about the metabolomic response of the hosts to T. canis infection. There is an increasing need to understand the metabolic mechanisms underlying the pathogenesis of T. canis infection in dogs. Here, we examined the metabolomic changes in Beagle dogsʼ serum following T. canis infection using LC-MS/MS.

Results

The metabolic profiles of Beagle dogsʼ serum were determined at 12 h, 24 h, 10 d and 36 d after oral infection with 300 infectious T. canis eggs by LC-MS/MS. We tested whether the T. canis-associated differentially abundant metabolites could distinguish the serum of infected dogs from controls, as measured by the area under the receiver operating characteristic (ROC) curve (AUC). The differentially expressed metabolites were further evaluated by principal components analysis and pathway enrichment analysis. A total of 5756 and 5299 ions were detected in ESI+ and ESI− mode, respectively. ROC curve analysis revealed nine and five metabolite markers, at 12 hpi and 24 hpi to 36 dpi, respectively, with potential diagnostic value for toxocariasis. The levels of taurocholate, estradiol, prostaglandins and leukotriene were significantly changed. Primary bile acid biosynthesis pathway, steroid hormone biosynthesis pathway and biosynthesis of unsaturated fatty acids pathway were significantly altered by T. canis infection.

Conclusions

These findings show that T. canis infection can induce several changes in the dog serum metabolome and that the metabolic signature associated with T. canis infection in dogs has potential for toxocariasis diagnosis.

Pharmacokinetic Characterizations of Ginsenoside Ocotillol, RT5 and F11, the Promising Agents for Alzheimer's Disease from American Ginseng, in Rats and Beagle Dogs

BACKGROUND

Ocotillol, RT5 and F11, the main active components of ocotillol type ginsenosides, have attracted a lot of attention due to their beneficial effects on neurodegenerative disease models of Alzheimer's disease. Pharmacokinetic (PK) is a bridge linking the herbal medicines and their pharmacological responses. However, few data are available regarding PK behaviors of ocotillol type ginsenosides.

METHODS

The liquid chromatography-tandem mass spectrometry methods were developed and validated to calculate the concentrations of 3 ginsenosides in different biological matrices. Rat and beagle dog plasma samples were deproteinized with methanol and separated on Shim-pack GIST C18 column. All of the analytes were detected in positive ion mode using multiple reaction monitoring.

RESULTS

The methods showed good linearity (r > 0.996) in the established concentration range. All validated data, such as specificity, intra- and inter-day precision, accuracy, extraction recovery, matrix effect, and stability were within required limits. The values of Cmax and AUC(0-t) indicated ocotillol type ginsenosides had low systemic exposure and poor absorption into blood. T1/2 and MRT(0-t) demonstrated the elimination process of ocotillol type ginsenosides might be slow. Double peaks were observed in the mean plasma concentration versus time profiles of ocotillol, RT5, and F11 after oral intake.

CONCLUSIONS

This was the first PK investigation of the ocotillol type ginsenosides in rats and beagle dogs. The results we found here were helpful to our understanding of the absorption mechanism of ocotillol type ginsenosides and provided the scientific basis for further pre-clinical research.

Linking (Pyr)1apelin-13 pharmacokinetics to efficacy: Stabilization and measurement of a high clearance peptide in rodents

Apelin, the endogenous ligand for the APJ receptor, has generated interest due to its beneficial effects on the cardiovascular system. Synthesized as a 77 amino acid preproprotein, apelin is post-translationally cleaved to a series of shorter peptides. Though (Pyr)¹apelin-13 represents the major circulating form in plasma, it is highly susceptible to proteolytic degradation and has an extremely short half-life, making it challenging to quantify. Literature reports of apelin levels in rodents have historically been determined with commercial ELISA kits which suffer from a lack of selectivity, recognizing a range of active and inactive isoforms of apelin peptide. (Pyr)¹apelin-13 has demonstrated beneficial hemodynamic effects in humans, and we wished to evaluate if similar effects could be measured in pre-clinical models. Despite development of a highly selective LC/MS/MS method, in rodent studies where (Pyr)¹apelin-13 was administered exogenously the peptide was not detectable until a detailed stabilization protocol was implemented during blood collection. Further, the inherent high clearance of (Pyr)¹apelin-13 required an extended release delivery system to enable chronic dosing. The ability to deliver sustained doses and stabilize (Pyr)¹apelin-13 in plasma allowed us to demonstrate for the first time the link between systemic concentration of apelin and its pharmacological effects in animal models.

[Biomechanical study on nickel-titanium three-dimensional memory alloy mesh combined with autologous bone for living model of canine tibial plateau collapse fracture]

Objective

To evaluate the effect of nickel-titanium three-dimensional memory alloy mesh combined with autologous bone for living model of canine tibial plateau collapse fracture by biomechanical testing.

Methods

Sixteen healthy 12-month-old Beagle dogs were randomly divided into 4 group, 4 dogs in each group. The dogs were used to establish the tibial plateau collapse fracture model in groups A, B, and C. Then, the nickel-titanium three-dimensional memory alloy mesh combined with autologous bone (the fibula cortical bone particles), the artificial bone (nano-hydroxyapatite), and autologous fibula cortical bone particles were implanted to repair the bone defects within 4 hours after modeling in groups A, B, and C, respectively; and the plate and screws were fixed outside the bone defects. The dogs were not treated in group D, as normal control. At 5 months after operation, all animals were sacrificed and the tibial specimens were harvested and observed visually. The destructive axial compression experiments were carried out by the biomechanical testing machine. The displacement and the maximum failure load were recorded and the axial stiffness was calculated.

Results

All animals stayed alive after operation, and all incisions healed. After 1-3 days of operation, the animals could stand and move, and no obvious limb deformity was found. The articular surfaces of the tibial plateau specimens were completely smooth at 5 months after operation. No obvious articular surface collapse was observed. The displacement and maximum failure load of specimens in groups A and D were significantly higher than those in groups B and C ( P<0.05). But no significant difference was found between groups A and D and between groups B and C ( P>0.05).

Conclusion

The nickel-titanium three-dimensional memory alloy mesh combined with autologous bone for subarticular bone defect of tibial plateau in dogs has good biomechanical properties at 5 months after operation, and has better axial stiffness when compared with the artificial bone and autologous bone graft.

The effect of low-magnitude high-frequency loading on peri-implant bone healing and implant osseointegration in Beagle dogs

PURPOSE

Low-magnitude, high-frequency (LMHF) loading plays an important role in bone healing. The present study aimed to evaluate the effect of LMHF loading applied directly to titanium dental implants on peri-implant bone healing and implant osseointegration.

METHODS

The mandibular premolars and molars were extracted from six male Beagle dogs. Three months post-extraction, each of the six dogs had three titanium implants (Aadva Standard Implant Narrow, Φ3.3×8mm) inserted into the mandibular premolar and molar area (three implants per side). In each animal, one side was randomly selected to undergo daily LMHF loading (treatment group), while the other side had no further intervention (control). The loading was applied directly to the implant abutment using an individual jig and a custom-made loading device (8μm, 100Hz). The implant stability quotient (ISQ) was tested every week. Three dogs were euthanized after 2 weeks, and three were euthanized after 8 weeks. Tissue samples were fixed and stained for micro-computed tomography (micro-CT) and histomorphometric analyses. Data were analyzed statistically, with significance set at p<0.05.

RESULTS

The treatment group had significantly increased peri-implant bone volume relative to tissue volume in region of interest 2 (100-500μm) compared with the control group after 2 weeks of loading (p<0.05); however, there was no significant difference between groups after 8 weeks. The ISQ value and the micro-CT results did not differ between groups during the study period.

CONCLUSIONS

LMHF loading positively influenced peri-implant bone healing in the early healing period.

Comparison of the osteogenesis and fusion rates between activin A/BMP-2 chimera (AB204) and rhBMP-2 in a beagle's posterolateral lumbar spine model

BACKGROUND CONTEXT

Activin A/BMP-2 chimera (AB204) could promote bone healing more effectively than recombinant bone morphogenetic protein 2 (rhBMP-2) with much lower dose in a rodent model, but there is no report about the effectiveness of AB204 in a large animal model.

PURPOSE

The purpose of this study was to compare the osteogenesis and fusion rate between AB204 and rhBMP-2 using biphasic calcium phosphate (BCP) as a carrier in a beagle's posterolateral lumbar fusion model.

STUDY DESIGN

This is a randomized control animal study.

METHODS

Seventeen male beagle dogs were included. Bilateral posterolateral fusion was performed at the L1-L2 and L4-L5 levels. Biphasic calcium phosphate (2 cc), rhBMP-2 (50 µg)+BCP (2 cc), or AB204 (50 µg)+BCP (2 cc) were implanted into the intertransverse space randomly. X-ray was performed at 4 and 8 weeks. After 8 weeks, the animals were sacrificed, and new bone formation and fusion rate were evaluated by manual palpation, computed tomography (CT), and undecalcified histology.

RESULTS

The AB204 group showed significantly higher fusion rate (90%) than the rhBMP-2 group (15%) or the Osteon group (6.3%) by manual palpation. On x-ray and CT assessment, fusion rate and the volume of newly formed bone were also significantly higher in AB204 group than other groups. In contrast, more osteolysis was found in rhBMP-2 group (40%) than in AB204 group (10%) on CT study. In histologic results, new bone formation was sufficient between transverse processes in AB204 group, and obvious trabeculation and bone remodeling were observed. But in rhBMP-2 group, new bone formation was less than AB204 group and osteolysis was observed between the intertransverse spaces.

CONCLUSIONS

A low dose of AB204 with BCP as a carrier significantly promotes the fusion rate in a large animal model when compared with the rhBMP-2. These findings demonstrate that AB204 could be an alternative to rhBMP-2 to improve fusion rate.

Repeated sub-chronic oral toxicity study of xylooligosaccharides (XOS) in dogs

In this study, Beagle dogs were administered xylooligosaccharide (XOS, CAS # 87099-0) at doses of 0, 1250, 2500, and 5000 mg/kg/day by oral gavage for 26 weeks. A 4-week recovery period was added to observe delayed or reversible toxicity. Measurements included body weight, food consumption, clinical observations, temperature, electrocardiogram (ECG), urinalysis, blood chemistry, hematology, organ weight, gross necropsy, and histopathological examination. Except for transient diarrhea or vomiting, no treatment-related adverse effects were noted. In the mid-dose groups, transitional diarrhea was observed in the initial 1-2 weeks. In the high-dose groups, diarrhea and/or vomiting were observed episodically over the duration of treatment. However, they disappeared after XOS was withdrawn in the recovery period. Although there was a tendency toward less weight gain in the high-dose group animal group, this is typical in animals and humans fed non-digestible carbohydrates. This chronic toxicity study demonstrated that the no observed adverse effect level (NOAEL) of XOS is 2500 mg/kg body weight (BW)/day. Based on body surface area (conversion factor of 0.54 for dogs to human), this corresponds to daily doses of 1350 mg/kg BW or 81-108 g XOS in human adults weighing 60-80 kg.

Magnetic resonance imaging assessment of the ventricular system in the brains of adult and juvenile beagle dogs treated with posaconazole IV Solution

INTRODUCTION

Noxafil® (posaconazole; POS) is a potent, selective triazole antifungal approved for use in adults as an oral suspension, oral tablet and intravenous (IV) Solution. In support of pediatric administration of POS IV Solution to children<two years of age, a nonclinical study in juvenile pre-weaning Beagle dogs was conducted, which showed enlarged lateral ventricles in the brain at the conclusion of a 6 week dosing period.

METHODS

To evaluate the impact of this finding on older age dogs, which would support administration to children>two years of age, two studies were undertaken using magnetic resonance imaging (MRI) to monitor brain ventricle size longitudinally during three months administration of POS IV in adult and juvenile dogs. Necropsy was performed on all animals at the end of the studies. From the baseline MRI images, great variability in ventricle size was noted in both the adult and juvenile dogs; these images were used to distribute differently sized ventricles between treatment and vehicle groups as to not skew group means during the course of the study.

RESULTS

POS IV Solution had no effect on ventricle volume at any timepoint during dosing in either the adult or the juvenile dogs. Further, no gross or histomorphologic differences between groups were observed in either study. Compared to juvenile dogs, MRI analysis showed that adult dogs had larger ventricles, lower variability in all ventricle volumes, and a greater rate of increase in total ventricle volume.

DISCUSSION

Information on growth and development of brains is one of the few areas in which more detailed information is available about humans than about the standard laboratory animals used to model disease and predict toxicities. The use of MRI helped elucidate large natural variabilities in the dog brain, which could have altered the interpretation of this de-risking study, and provided a valuable noninvasive means to monitor the brain ventricles longitudinally.

S-carboxymethyl-L-cysteine and it (R/S)-S-oxides in beagle dog plasma and hepatic cytosol

1. Incubation of beagle hepatic cytosol, under conditions promoting phenylalanine hydroxylase activity, led to the formation of the sulfoxide derivatives of S-carboxymethyl-L-cysteine, N-acetyl-S-carboxymethyl-L-cysteine, S-methyl-L-cysteine and N-acetyl-S-methyl-L-cysteine. Thiodiglycolic acid was not a substrate. Enzyme kinetic parameters (Km, Vmax) were derived indicating S-carboxymethyl-L-cysteine had the greatest clearance; no enantioselective preference was observed for this S-oxygenation reaction. 2. Following oral administration of S-carboxymethyl-L-cysteine to beagle dogs, the parent substance and its sulfoxide were the only compounds identified in the plasma. Pharmacokinetic data have been obtained indicating that the small amount of sulfoxide formed persisted within the body for longer than the parent material, but that the majority of the ingested dose remained in the administered sulfide form. 3. The sulfide moiety within the muco-regulatory drug, S-carboxymethyl-L-cysteine, is thought to be vital as it acts as a free radical scavenger, resulting in the inactive sulfoxide. Additional extensive enyzme-mediated sulfoxidation would decrease the amount of active sulfide available. In the dog this appears to not be an issue, signalling possible exploitation for therapeutic benefit in treating airway disease.

Spontaneous necrotizing sialometaplasia of the submandibular salivary gland in a Beagle dog

A single mass was found on the left submandibular salivary gland at necropsy of a 15-month-old male commercially bred laboratory Beagle dog from a control dose group from a repeat toxicity study. Microscopically, the mass was composed of a well-demarcated area of coagulative necrosis surrounded and separated from the normal salivary gland tissue by a thick fibrovascular capsule. Necrosis was admixed with areas of hemorrhage, fibrin, edema, fibrinoid necrosis of the vascular tunica media, and thrombosis of small and large vessels. Within the necrotic tissue, there was marked ductal hyperplasia, and squamous metaplasia of duct and acinar epithelium. The mass was diagnosed as necrotizing sialometaplasia of the submandibular gland. Hyperplastic ductal elements and squamous metaplasia can be mistaken microscopically with squamous cell carcinoma. Therefore, pathologists should be aware of this lesion as to avoid errors in the diagnosis of this benign pathologic condition.

The evaluation of drug-induced changes in cardiac inotropy in dogs: Results from a HESI-sponsored consortium

INTRODUCTION

Drug-induced effects on the cardiovascular system remain a major cause of drug attrition. While hemodynamic (blood pressure (BP) and heart rate (HR)) and electrophysiological methods have been used in testing drug safety for years, animal models for assessing myocardial contractility are used less frequently and their translation to humans has not been established. The goal of these studies was to determine whether assessment of contractility and hemodynamics, when measured across different laboratories using the same protocol, could consistently detect drug-induced changes in the inotropic state of the heart using drugs known to have clinically relevant positive and negative effects on myocardial contractility.

METHODS

A 4×4 double Latin square design (n=8) design using Beagle dogs was developed. Drugs were administrated orally. Arterial blood pressure, left ventricular pressure (LVP) and the electrocardiogram were assessed. Each of the six laboratories studied at least 2 drugs (one positive inotrope (pimobendan or amrinone) and one negative inotrope) (itraconazole or atenolol) at 3 doses selected to match clinical exposure data and a vehicle control. Animals were instrumented with an ITS telemetry system, DSI's D70-PCTP system or DSI's Physiotel Digital system. Data acquisition and analysis systems were Ponemah, Notocord or EMKA.

RESULTS

Derived parameters included: diastolic, systolic and mean arterial BP, peak systolic LVP, HR, end-diastolic LVP, and LVdP/dtmax as the primary contractility index. Blood samples were drawn to confirm drug exposures predicted from independent pharmacokinetic studies. Across the laboratories, a consistent change in LVdP/dtmax was captured despite some differences in the absolute values of some of the hemodynamic parameters prior to treatment.

DISCUSSION

These findings indicate that this experimental model, using the chronically instrumented conscious dog, can accurately and consistently detect changes in cardiac contractility, across multiple sites and instrumentation systems, and that data obtained in this model may also translate to clinical outcomes.

Invivo absorption behaviour of theophylline from starch-methyl methacrylate matrix tablets in beagle dogs

This study evaluates in vivo the drug absorption profiles from potato starch-methyl methacrylate matrices(*) using theophylline as a model drug. Healthy beagle dogs under fasting conditions were used for in vivo studies and plasma samples were analyzed by a fluorescence polarization immunoassay analysis (FPIA method). Non-compartmental and compartmental (population approach) analysis was performed to determine the pharmacokinetic parameters. The principle of superposition was applied to predict multiple dose plasma concentrations from experimental single dose data. An in vitro-in vivo correlation (IVIVC) was also assessed. The sustained absorption kinetics of theophylline from these formulations was demonstrated by comparison with two commercially available oral sustained-release theophylline products (Theo-Dur(®) and Theolair(®)). A one-compartment model with first order kinetics without lag-time best describes the absorption/disposition of theophylline from the formulations. Results revealed a theophylline absorption rate in the order FD-HSMMA≥Theo-Dur(®)≥OD-CSMMA>Theolair(®)≥FD-CSMMA. On the basis of simulated plasma theophylline levels, a twice daily dosage (every 12h) with the FD-CSMMA tablets should be recommended. A Level C IVIVC was found between the in vitrot50% and the in vivo AUC/D, although further optimization of the in vitro dissolution test would be needed to adequately correlate with in vivo data.

Pharmacokinetics of propafenone hydrochloride sustained-release capsules in male beagle dogs

This paper describes the development and validation of a liquid chromatography-mass spectrometric assay for propafenone and its application to a pharmacokinetic study of propafenone administered as a new propafenone hydrochloride sustained-release capsule (SR-test), as an instant-release tablet (IR-reference) and as the market leader sustained-release capsule (Rythmol, SR-reference) in male beagle dogs (n=8). In Study A comparing SR-test with IR-reference in a crossover design T max and t 1/2 of propafenone for SR-test were significantly higher than those for IR-reference while C max and AUC were lower demonstrating the sustained release properties of the new formulation. In Study B comparing SR-test with SR-reference the observed C max and AUC of propafenone for SR-test (124.5±140.0 ng/mL and 612.0±699.2 ng·h/mL, respectively) were higher than for SR-reference (78.52±72.92 ng/mL and 423.6±431.6 ng·h/mL, respectively) although the differences were not significant. Overall, the new formulation has as good if not better sustained release characteristics to the market leader formulation.

Invivo absorption behaviour of theophylline from starch-methyl methacrylate matrix tablets in beagle dogs

This study evaluates in vivo the drug absorption profiles from potato starch-methyl methacrylate matrices(*) using theophylline as a model drug. Healthy beagle dogs under fasting conditions were used for in vivo studies and plasma samples were analyzed by a fluorescence polarization immunoassay analysis (FPIA method). Non-compartmental and compartmental (population approach) analysis was performed to determine the pharmacokinetic parameters. The principle of superposition was applied to predict multiple dose plasma concentrations from experimental single dose data. An in vitro-in vivo correlation (IVIVC) was also assessed. The sustained absorption kinetics of theophylline from these formulations was demonstrated by comparison with two commercially available oral sustained-release theophylline products (Theo-Dur(®) and Theolair(®)). A one-compartment model with first order kinetics without lag-time best describes the absorption/disposition of theophylline from the formulations. Results revealed a theophylline absorption rate in the order FD-HSMMA≥Theo-Dur(®)≥OD-CSMMA>Theolair(®)≥FD-CSMMA. On the basis of simulated plasma theophylline levels, a twice daily dosage (every 12h) with the FD-CSMMA tablets should be recommended. A Level C IVIVC was found between the in vitrot50% and the in vivo AUC/D, although further optimization of the in vitro dissolution test would be needed to adequately correlate with in vivo data.

Characterisation of tramadol, morphine and tapentadol in an acute pain model in Beagle dogs

OBJECTIVE

To evaluate the analgesic potential of the centrally acting analgesics tramadol, morphine and the novel analgesic tapentadol in a pre-clinical research model of acute nociceptive pain, the tail-flick model in dogs.

STUDY DESIGN

Prospective part-randomized pre-clinical research trial.

ANIMALS

Fifteen male Beagle dogs (HsdCpb:DOBE), aged 12-15 months.

METHODS

On different occasions separated by at least 1 week, dogs received intravenous (IV) administrations of tramadol (6.81, 10.0 mg kg(-1) ), tapentadol (2.15, 4.64, 6.81 mg kg(-1) ) or morphine (0.464, 0.681, 1.0 mg kg(-1) ) with subsequent measurement of tail withdrawal latencies from a thermal stimulus (for each treatment n = 5). Blood samples were collected immediately after the pharmacodynamic measurements of tramadol to determine pharmacokinetics and the active metabolite O-demethyltramadol (M1).

RESULTS

Tapentadol and morphine induced dose-dependent antinociception with ED50-values of 4.3 mg kg(-1) and 0.71 mg kg(-1) , respectively. In contrast, tramadol did not induce antinociception at any dose tested. Measurements of the serum levels of tramadol and the M1 metabolite revealed only marginal amounts of the M1 metabolite, which explains the absence of the antinociceptive effect of tramadol in this experimental pain model in dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

Different breeds of dogs might not or only poorly respond to treatment with tramadol due to low metabolism of the drug. Tapentadol and morphine which act directly on μ-opioid receptors without the need for metabolic activation are demonstrated to induce potent antinociception in the experimental model used and should also provide a reliable pain management in the clinical situation. The non-opioid mechanisms of tramadol do not provide antinociception in this experimental setting. This contrasts to many clinical situations described in the literature, where tramadol appears to provide useful analgesia in dogs for post-operative pain relief and in more chronically pain states.

Determination of Prostaglandin E1 in dog plasma using liquid chromatography-tandem mass spectrometry and its application to a pharmacokinetic study

The determination of Prostaglandin (PG) E1 in plasma is challenged by its low concentration (pg/mL) and endogenous interference. An LC-MS/MS method for the determination of PGE1 in dog plasma has been developed and validated. Plasma being sampled at 4°C and treated with indomethacin effectively inhibited interferents synthesized post-sampling. Samples were subjected to one-step extraction and separated by reversed phase HPLC with a short cycle time of 3min. An LLOQ of 10pg/mL was achieved with 500μl plasma. The method was applied to a pharmacokinetic study in beagle dogs involving an intravenous infusion of 3.2μg/kg PGE1. The half-life was recovered at 7min. The simple, sensitive and rapid method was suitable to be applied to pharmacokinetic studies of PGE1 at clinically relevant doses.