Monitoring muscle over three orders of magnitude: Widespread positive allometry among locomotor and body support musculature in the pectoral girdle of varanid lizards (Varanidae)

There is a functional trade-off in the design of skeletal muscle. Muscle strength depends on the number of muscle fibers in parallel, while shortening velocity and operational distance depend on fascicle length, leading to a trade-off between the maximum force a muscle can produce and its ability to change length and contract rapidly. This trade-off becomes even more pronounced as animals increase in size because muscle strength scales with area (length²) while body mass scales with volume (length³). In order to understand this muscle trade-off and how animals deal with the biomechanical consequences of size, we investigated muscle properties in the pectoral girdle of varanid lizards. Varanids are an ideal group to study the scaling of muscle properties because they retain similar body proportions and posture across five orders of magnitude in body mass and are highly active, terrestrially adapted reptiles. We measured muscle mass, physiological cross-sectional area, fascicle length, proximal and distal tendon lengths, and proximal and distal moment arms for 27 pectoral girdle muscles in 13 individuals across 8 species ranging from 64 g to 40 kg. Standard and phylogenetically informed reduced major axis regression was used to investigate how muscle architecture properties scale with body size. Allometric growth was widespread for muscle mass (scaling exponent >1), physiological cross-sectional area (scaling exponent >0.66), but not tendon length (scaling exponent >0.33). Positive allometry for muscle mass was universal among muscles responsible for translating the trunk forward and flexing the elbow, and nearly universal among humeral protractors and wrist flexors. Positive allometry for PCSA was also common among trunk translators and humeral protractors, though less so than muscle mass. Positive scaling for fascicle length was not widespread, but common among humeral protractors. A higher proportion of pectoral girdle muscles scaled with positive allometry than our previous work showed for the pelvic girdle, suggesting that the center of mass may move cranially with body size in varanids, or that the pectoral girdle may assume a more dominant role in locomotion in larger species. Scaling exponents for physiological cross-sectional area among muscles primarily associated with propulsion or with a dual role were generally higher than those associated primarily with support against gravity, suggesting that locomotor demands have at least an equal influence on muscle architecture as body support. Overall, these results suggest that larger varanids compensate for the increased biomechanical demands of locomotion and body support at higher body sizes by developing larger pectoral muscles with higher physiological cross-sectional areas. The isometric scaling rates for fascicle length among locomotion-oriented pectoral girdle muscles suggest that larger varanids may be forced to use shorter stride lengths, but this problem may be circumvented by increases in limb excursion afforded by the sliding coracosternal joint.     

Two‐Stage Basilic Vein Transposition: Second Stage Results

The increasing survival of hemodialysis patients results in the depletion of superficial venous capital justifying the use of the basilic vein. Many groups still prefer an arteriovenous graft due to transposition complexity and the time needed to achieve maturation. In this work we review the results of our series of basilic vein transpositions (BVT). BVTs were performed in two stages: first, creation of the fistula; second, transposition of the vein using three small incisions in the arm. All patients had to have direct arterialization of the basilic vein, therefore, patients with previous ipsilateral wrist fistulas also followed a two‐stage protocol. Data were retrospectively revised from all transposition procedures made between September 2005 and November 2012. Patency and complication rates were the primary outcomes evaluated. A total of 276 basilic veins were transposed. Usage rate was 82.2%. 8% (N = 22) of the fistulas were never used due to thrombosis. Secondary patency rates at 1 and 2 years were, respectively, 84% and 66.3%. Complications occurred in 61.6% (N = 170) of fistulas and 65.9% (N = 112) of which had to undergo surgical or endovascular revision. The most frequent complication was vein stenosis (39.7% of late complications, N = 92). Albeit its greater technical complexity, the transposed basilic vein represents a hemodialysis access with good patency rates. Complication rates, although high, are less than those of CVC or prosthetic grafts. These results support the use of the transposed basilic vein as hemodialysis access after the brachiocephalic fistula.     

Longitudinal changes of microbiome composition and microbial metabolomics after surgical weight loss in individuals with obesity

BackgroundSome of the metabolic effects of bariatric surgery may be mediated by the gut microbiome.ObjectivesTo study the effect of bariatric surgery on changes to gut microbiota composition and bacterial pathways, and their relation to metabolic parameters after bariatric surgery.SettingsUniversity hospitals in the United States and Spain.MethodsMicrobial diversity and composition by 16 S rRNA sequencing, putative bacterial pathways, and targeted circulating metabolites were studied in 26 individuals with severe obesity, with and without type 2 diabetes, before and at 3, 6, and 12 months after either gastric bypass or sleeve gastrectomy.ResultsBariatric surgery tended to increase alpha diversity, and significantly altered beta diversity, microbiota composition, and function up to 6 months after surgery, but these changes tend to regress to presurgery levels by 12 months. Twelve of 15 bacterial pathways enriched after surgery also regressed to presurgery levels at 12 months. Network analysis identified groups of bacteria significantly correlated with levels of circulating metabolites over time. There were no differences between study sites, surgery type, or diabetes status in terms of microbial diversity and composition at baseline and after surgery.ConclusionsThe association among changes in microbiome with decreased circulating biomarkers of inflammation, increased bile acids, and products of choline metabolism and other bacterial pathways suggest that the microbiome partially mediates improvement of metabolism during the first year after bariatric surgery.     

Convergence in Spanish Public health expenditure: Has the decentralization process generated disparities?

This study examines the per capita public health expenditures among the Spanish regions. To that end, we employ the database elaborated by the BBVA Fundation and IVIE (2013) which covers the years 1991–2010. We first test for the null hypothesis of convergence by employing the methodology proposed in Phillips and Sul (2007) in order to determine whether the evolution of the public health expenditures has followed a similar path across the Spanish regions. This methodology leads us to reject the null hypothesis of convergence, which implies the absence of a unique pattern of behavior in the evolution of the Spanish regional public health expenditures. Instead, we find several convergence clubs which reveal the existence of different patterns of behavior and serious disparities in the Spanish health system. When trying to determine the forces which drive the creation of these clubs, we also find some partisan behavior, in the sense that the longer a right-wing party governs, the lower the per capita public health expenditure in this region of Spain.     

Delayed presentation of inflammatory breast carcinoma during the COVID-19 pandemic

European Surgery - Breast cancer may present with distinct cutaneous manifestations that may be paraneoplastic or secondary to direct skin infiltration, distant skin metastases, or dermal lymphatic...     

Understanding the role of microperimetry in glaucoma

International Ophthalmology - The present narrative review attempts to provide an overview on the use of microperimetry or fundus-driven perimetry in glaucoma, considering the clinical use, the...     

Evolution of Surgical Treatment of Amebiasis-Associated Colon Perforation

Background  

Amebiasis is a worldwide health problem that mainly affects developing countries. Invasive amebiasis tends to develop complications, and among these, perforation of the colon, although infrequent (1.9–9.1%), is the most lethal. Surgical treatment in these cases should be carried out in a timely fashion prior to the presentation of systemic repercussions or death. In the present study, we analyzed a total of 122 cases of invasive amebiasis-associated colon perforation.