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- Author or Editor: Laura Zarucco x
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Abstract
Objective—To provide a quantitative description of the architecture of superficial digital flexor (SDF) and deep digital flexor (DDF) muscles in adult horses to predict muscle-tendon behavior and estimate muscle forces.
Sample Population—7 forelimb specimens from 7 adult Thoroughbreds.
Procedure—Muscle and tendon lengths and volumes were measured from 6 fixed forelimbs. After processing, fiber bundle and sarcomere lengths were measured. Optimal fascicle lengths and muscle length-to-fascicle length, muscle length-to-free tendon length, and fascicle length-to-tendon length ratios were calculated, as were tendon and muscle physiologic cross-sectional areas (PCSAs). Pennation angles were measured in 1 embalmed specimen.
Results—The SDF optimal fascicle lengths were uniformly short (mean ± SD, 0.8 ± 0.1 cm), whereas DDF lengths ranged from 0.9 ± 0.2 cm to 10.8 ± 1.6 cm. The DDF humeral head had 3 architectural subunits, each receiving a separate median nerve branch, suggestive of neuromuscular compartmentalization. Pennation angles were small (10o to 25o). The PCSAs of the SDF and DDF muscle were 234 ± 51 cm2 and 259 ± 30 cm2, with estimated forces of 4,982 ± 1148 N and 5,520 ± 544 N, respectively.
Conclusions and Clinical Relevance—The SDF muscle appears to provide strong tendinous support with little muscle fascicular shortening and fatigueresistance properties. The DDF muscle combines passive and dynamic functions with larger tension development and higher shortening velocities during digital motion. Architectural parameters are useful for estimation of forces and have implications for analysis of muscle-tendon function, surgical procedures involving muscle-tendon lengthening, and biomechanical modeling. (Am J Vet Res 2004;65:819–828)
Abstract
OBJECTIVE
To evaluate effects of poly(ADP-ribose) polymerase-1 (PARP1) inhibitors on the production of tumor necrosis factor-α (TNF-α) by interferon-γ (IFN-γ)– and lipopolysaccharide (LPS)-stimulated peripheral blood mononuclear cells (PBMCs) of horses as an in vitro model of inflammation in horses.
SAMPLE
1,440 samples of PBMCs from 6 healthy research horses.
PROCEDURES
From heparinized whole blood samples, PBMC cultures were obtained. An initial dose-response trial on 48 PBMC samples from 2 horses (24 samples each) was used to determine concentrations of IFN-γ and LPS for use as low- and high-level stimulation concentrations. Seventy-two PBMC samples from 6 horses were assigned equally to 1 of 4 PARP1 inhibition categories: no PARP1 inhibitor (PARP1 inhibition control); 2-((R)-2-methylpyrrolidin-2-yl)-1H-benzimidazole-4-carbozamide dihydrochloride (ABT888);4-(3-(1-(cyclopropanecarbonyl)piperazine-4-carbonyl)-4-fluorobenzyl)phthalazin-1(2H)-one (AZD2281); or N-(6-oxo-5,6-dihydrophenanthridin-2-yl) -N,N-dimethylacetamide hydrochloride (PJ34). Samples of PBMCs from each horse and each PARP1 inhibition category were then assigned to 1 of 3 levels of IFN-γ and LPS stimulation: none (control), low stimulation, or high stimulation. After a 24-hour incubation period, a TNF-α ELISA was used to measure TNF-α concentration in the supernatant. Results were compared across treatments and for each horse. Data were analyzed with repeated-measures ANOVA.
RESULTS
Median TNF-α concentration was significantly lower for PJ34-treated, high-level stimulated PBMCs than for PARP1 inhibition control, high-level stimulated PBMCs; however, no other meaningful differences in TNF-α concentration were detected among the inhibition and stimulation combinations.
CONCLUSIONS AND CLINICAL RELEVANCE
Findings suggested that PJ34 PARP1 inhibition may reduce TNF-α production in horses, a potential benefit in reducing inflammation and endotoxin-induced damage in horses.
