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Qingqing Liang

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The processes governing soil bacteria biogeography are still not fully understood. It remains unknown how the importance of environmental filtering and dispersal differs between bacterial taxonomic and functional biogeography, and whether their importance is scale-dependent. We sampled soils at 195 plots across the Tibet plateau, with distances among plots ranging from 20 m to 1 550 km. Taxonomic composition of bacterial community was characterized by 16S amplicon sequencing, and functional community composition by qPCR targeting 9 functional groups involved in N dynamics. Twelve climatic and soil characteristics were also measured. Both taxonomic and functional dissimilarities were more related to environmental dissimilarity than geographic distance. Taxonomic dissimilarity was mostly explained by soil pH and organic matter, while functional dissimilarity was mostly linked to moisture, temperature and N, P and C availabilities. The roles of environmental filtering and dispersal were, however, scale-dependent and varied between taxonomic and functional dissimilarities, with distance affecting taxonomic dissimilarity over short distances (<~300 km) and functional dissimilarity over long distances (>~600 km). The importance of different environmental predictors varied across scales more for functional than taxonomic dissimilarity. Our results demonstrate how biodiversity dimension (taxonomic versus functional) and spatial scale strongly influence the conclusions derived from bacterial biogeography studies.

Monique Boekema

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Aim: The effect of the Dutch nationwide adjustment of reduced 6-TGN target values (from 600-1200 pmol/8x108 RBC to 320-630 pmol/8x108 RBC) on toxicity and clinical outcome of thiopurine treatment in patients with inflammatory bowel disease (IBD) has not yet been established. Therefore the authors determined the incidence of toxicity-induced discontinuations and efficacy at both target concentrations. Methods: This retrospective study was performed in IBD patients treated with azathioprine or mercaptopurine. Two groups were defined: the former target (FT) group with target concentrations of 600-1200 pmol/8x10^8 RBC and the adjusted target (AT) group with target concentrations of 320-630 pmol/8x10^8 RBC. Patients were followed for maximum 52 weeks or until discontinuation of thiopurine therapy. Data were collected from the local hospital electronic health software of Rijnstate Hospital. Results: 151 patients were included, 76 in the FT group and 75 in the AT group. At week 52, 100 out of 150 patients (66%) of the total population discontinued thiopurine therapy. Forty-eight of this discontinuations were due toxicity (48%). The estimated cumulative incidence of toxicity was higher in the FT group compared to the AT group (47% and 35% respectively, p=0.25). No loss of efficacy was seen in the AT group. Conclusion: Reduction of the target range may lead to less toxicity induced discontinuations. In addition, this study did not find any indication that the reduction of the target range diminished efficacy.

Qianheng Jin

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Aurélie Baliarda

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Ramsey Elsayed

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Response to Letter to Editor Regarding: Equivalent outcomes with minimally invasive and sternotomy mitral valve repair for degenerative mitral valve disease. J Card Surg. 2021; 36:2636-43.Authors: Ramsey S. Elsayed, MD MS1, Brittany Abt, MD1, and Michael E. Bowdish, MD MS1,2Institutions and Affiliations: 1Division of Cardiac Surgery, Department of Surgery, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, USA2Department of Preventive Medicine, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, USAAddress for Correspondence: Dr. Michael E. Bowdish, Associate Professor of Surgery and Preventive Medicine; Department of Surgery, Keck School of Medicine of USC; University of Southern California; 1520 San Pablo Street, HCC II Suite 4300; Los Angeles, CA 90033; Phone: (323)-442-5849; Email: Michael.Bowdish@med.usc.eduConflicts of Interest/Competing Interests: NoneFunding: Research reported in this publication was supported by the Department of Surgery of the Keck School of Medicine of USC. MEB is partially supported by UM1-HL11794 from the National Heart Lung and Blood Institute of the National Institutes of Health.To the editor,We would like to thank Song et. al. for their letter regarding our recent publication in the Journal of Cardiac Surgery titled “Equivalent outcomes with minimally invasive and sternotomy mitral valve repair for degenerative mitral valve disease”1. They asked some important questions and brought up valuable points that are worthy of discussion.Regarding the selection criteria we use for operative approach for mitral valve repair operations, it is primarily based on collective surgeon-patient decision making. However, patients with a previous history of cardiac surgery or peripheral vascular disease (which would render peripheral cannulation difficult), and those in need of concomitant cardiac procedures such as coronary artery bypass grafting, aortic replacement, or biatrial ablation, are not offered a minimally invasive approach. Regarding the role of artificial chordae (neochordae) in mitral valvuloplasty, we use elongated polytetrafluorethylene made of interrupted GoreTex (Gore-Tex, WL Gore and Associates, Inc., Flagstaff, AZ) sutures placed in a horizontal mattress fashion. These neochordae are routinely used to repair elongated or ruptured chordae causing mitral valve prolapse or regurgitation.2 Typically, the neochordae are used in the anterior leaflet of the mitral valve. The etiologies of degenerative mitral valve disease are comprised of myxomatous degeneration of the MV, fibroelastic deficiency including so called Barlow’s valves, and dystrophic calcification of the mitral annulus.3 While the etiologies are not mutually exclusive and may overlap, myxomatous degeneration and fibroelastic deficiencies resulting in severe, symptomatic MR were the most common indications for operation in our patient population. As mentioned by Song and colleagues, the success and durability of MVr can vary depending on etiology, particularly on how much of the valve apparatus is affected by pathology. While not examined in this paper specifically, previous papers (including Tatum et al. conducted at our institution), have demonstrated that anterior leaflet repair is significantly associated with recurrence and progression of MR after surgery, whereas isolated posterior repair is protective.3,4The operative team was similar in all cases, whereas the senior author (VAS) performed over 85% of the total procedures and nearly 100% of the minimally invasive procedures. The success rate of the minimally invasive cohort was 100% (as defined by the Society of Thoracic Surgeons). There was one conversion to conventional sternotomy in the minimally invasive cohort (.003%) for bleeding control.Finally, Song and colleagues are to be congratulated on their robotic and thoracoscopic mitral valvuloplasty results. Their 10-year total robotic mitral valve valvuloplasty results showing excellent cardiac function with 93% of patients in NYHA classes I and II.5 Furthermore, their early thoracoscopic results were very good with one operative mortality and only two reoperations demonstrating thoracoscopic mitral valvuloplasty is a technically feasible, safe, effective, and reproducible technique.6References:Bowdish ME, Elsayed RS, Tatum JM, Cohen RG, Mack WJ, Abt B, Yin V, Barr ML, Starnes VA. Equivalent outcomes with minimally invasive and sternotomy mitral valve repair for degenerative mitral valve disease. J Card Surg. 2021 Aug;36(8):2636-2643. PMID: 33908645.Bortolotti U, Milano AD, Frater RW. Mitral valve repair with artificial chordae: a review of its history, technical details, long-term results, and pathology. Ann Thorac Surg. 2012 Feb;93(2):684-91. PMID: 22153050.David, Tirone E. ”Durability of mitral valve repair for mitral regurgitation due to degenerative mitral valve disease.” Annals of cardiothoracic surgery 4.5 (2015): 417.Tatum, James M., et al. ”Outcomes after mitral valve repair: a single-center 16-year experience.” The Journal of thoracic and cardiovascular surgery 154.3 (2017): 822-830.Zhao H, Gao C, Yang M, Wang Y, Kang W, Wang R, Zhang H. Surgical effect and long-term clinical outcomes of robotic mitral valve replacement: 10-year follow-up study. J Cardiovasc Surg (Torino). 2021 Apr;62(2):162-168. PMID: 33302613.Cui H, Zhang L, Wei S, Li L, Ren T, Wang Y, Jiang S. Early clinical outcomes of thoracoscopic mitral valvuloplasty: a clinical experience of 100 consecutive cases. Cardiovasc Diagn Ther. 2020 Aug;10(4):841-848. PMCID: PMC7487400.

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