Comparison of diameter and length of subclavian arteries to external jugular veins in variably sized dogs: A cadaveric study.

OBJECTIVE: To evaluate the length and diameter of a left external jugular vein graft as a substitute for the left subclavian artery in the modified Blalock-Thomas-Taussig shunt (mBTTS) in differently sized dogs. STUDY DESIGN: Cadaveric study. ANIMALS: Dog cadavers of three weight categories (10/group): <9.5 kg, 9.5 to 27 kg, and > 27 kg. METHODS: The length and infused external diameters of harvested vessels were measured with vernier calipers and recorded. A matched-pairs t test was used to test the difference in vessel lengths. The agreement in vessel diameters was assessed by using Lin's concordance correlation coefficient (CCC). Pearson's correlation coefficients (CC) were determined for vessel diameter to weight category and vessel length to weight category. RESULTS: The external jugular vein measured longer than the subclavian artery in all dogs (52.0 ± 20.8 mm and 23.0 ± 8.9 mm, respectively), with a mean difference of 28 ± 14.3 mm (P < .001). The mean external infused subclavian and external jugular diameters measured 7.8 ± 2.2 mm and 8.0 ± 2.5 mm, respectively (P = .32). Lin's CCC was 0.87. Pearson's CC were 0.74 in both vessel diameters (P < .001); they were 0.36 and 0.43, respectively, for subclavian artery and external juglar vein length (P < .001). CONCLUSION: Autologous external jugular vein grafts had an external diameter similar to subclavian artery and a significantly longer length in variably sized dogs. CLINICAL SIGNIFICANCE: External jugular vein grafts may be an acceptable graft choice for mBTTS.

Antibiotic-induced Disruption of Intestinal Microbiota Contributes to Failure of Vertical Sleeve Gastrectomy.

OBJECTIVE: The aim of this study was to test whether the perioperative composition of intestinal microbiota can contribute to variable outcomes following vertical sleeve gastrectomy (VSG). SUMMARY OF BACKGROUND DATA: Although bariatric surgery is the most effective treatment for obesity, metabolic outcomes are variable. METHODS: Diet-induced obese mice were randomized to VSG or sham surgery, with or without exposure to antibiotics that selectively suppress mainly gram-positive (fidaxomicin, streptomycin) or gram-negative (ceftriaxone) bacteria on postoperative days (POD) 1-4. Fecal microbiota was characterized before surgery and on POD 7 and 28. Mice were metabolically characterized on POD 30-32 and euthanized on POD 35. RESULTS: VSG resulted in weight loss and shifts in the intestinal microbiota composition relative to sham-operated mice. Antibiotic exposure resulted in sustained reductions in alpha (within-sample) diversity of microbiota and shifts in its composition. All antibiotic treatments proved to be detrimental to metabolic VSG outcomes, regardless of antimicrobial specificity of antibiotics. These effects involved functionally distinct pathways. Specifically, fidaxomicin and streptomycin markedly altered hepatic bile acid signaling and lipid metabolism, while ceftriaxone resulted in greater reduction of key antimicrobial peptides. However, VSG mice exposed to antibiotics, regardless of their specificity, had significantly increased subcutaneous adiposity and impaired glucose homeostasis without changes in food intake relative to control VSG mice. CONCLUSION: Dysbiosis induced by brief perioperative antibiotic exposure attenuates weight loss and metabolic improvement following VSG. Potential mechanisms include disruption of bile acid homeostasis and reduction in the production of gut antimicrobial peptides. Results of this study implicate the intestinal microbiota as an important contributor to metabolic homeostasis and a potentially modifiable target influencing clinical outcomes following VSG.

Restriction Site-Associated DNA Sequencing (RAD-seq) Reveals an Extraordinary Number of Transitions among Gecko Sex-Determining Systems.

Sex chromosomes have evolved many times in animals and studying these replicate evolutionary "experiments" can help broaden our understanding of the general forces driving the origin and evolution of sex chromosomes. However this plan of study has been hindered by the inability to identify the sex chromosome systems in the large number of species with cryptic, homomorphic sex chromosomes. Restriction site-associated DNA sequencing (RAD-seq) is a critical enabling technology that can identify the sex chromosome systems in many species where traditional cytogenetic methods have failed. Using newly generated RAD-seq data from 12 gecko species, along with data from the literature, we reinterpret the evolution of sex-determining systems in lizards and snakes and test the hypothesis that sex chromosomes can routinely act as evolutionary traps. We uncovered between 17 and 25 transitions among gecko sex-determining systems. This is approximately one-half to two-thirds of the total number of transitions observed among all lizards and snakes. We find support for the hypothesis that sex chromosome systems can readily become trap-like and show that adding even a small number of species from understudied clades can greatly enhance hypothesis testing in a model-based phylogenetic framework. RAD-seq will undoubtedly prove useful in evaluating other species for male or female heterogamety, particularly the majority of fish, amphibian, and reptile species that lack visibly heteromorphic sex chromosomes, and will significantly accelerate the pace of biological discovery.

Canine mitral valve size as measured by computed tomography.

OBJECTIVE: To measure the mitral annulus in dogs. Our hypothesis was that mitral measurement would be possible and consistent among observers using CT. SAMPLE: Thoracic CT scans of dogs without known heart disease. PROCEDURES: Five trained investigators measured 4 aspects of the mitral valve and the fourth thoracic vertebrae (T4) length using multiplanar reformatting tools. Ten randomly chosen animals were measured by all investigators to determine interobserver reliability. RESULTS: There were 233 CT scans eligible for inclusion. Dogs weighed 2 to 96 kg (mean, 28.1 kg), with a variety of breeds represented. Golden Retrievers (n = 28) and Labrador Retrievers (n = 37) were overrepresented. The intraclass correlations were all greater than 0.9, showing excellent agreement between observers. The means and SDs of each measurement were as follows: trigone-to-trigone distance, 17.2 ± 4.7 mm; the remaining circumference, 79.0 ± 17.5 mm; commissure-to-commissure distance, 30.8 ± 6.5 mm; septal leaflet-to-lateral leaflet distance, 26.3 ± 6.0 mm; T4 length, 16.9 ± 3.1 mm; and the total circumference normalized by T4, 5.7 ± 0.7 mm. CLINICAL RELEVANCE: This study provides information that may help in the development of future treatment for mitral valve dysfunction and subsequent annular enlargement.