Impact of Mitral Valve Repair Case Volume on Postoperative Mortality　- A Nationwide Korean Cohort Study.

BACKGROUND: Although mitral valve repair is recommended over replacement due to better outcomes, repair rates vary significantly among centers. This study examined the effect of institutional mitral valve repair volume on postoperative mortality.Methods and Results:All cases of adult mitral valve repair performed in Korea between 2009 and 2016 were analyzed. The association between case volume and 1-year mortality was analyzed after categorizing centers according to the number of mitral valve repairs performed as low-, medium-, or high-volume centers (<20, 20-40, and >40 cases/year, respectively). The effect of case volume on cumulative all-cause mortality was also assessed. In all, 6,041 mitral valve repairs were performed in 86 centers. The 1-year mortality in low-, medium-, and high-volume centers was 10.1%, 8.7%, and 4.7%, respectively. Low- and medium-volume centers had increased risk of 1-year mortality compared with high-volume centers, with odds ratios of 2.80 (95% confidence interval [CI] 2.15-3.64; P<0.001) and 2.66 (95% CI 1.94-3.64; P<0.001), respectively. The risk of cumulative all-cause mortality was also worse in low- and medium-volume centers, with hazard ratios of 1.96 (95% CI 1.68-2.29; P<0.001) and 1.77 (95% CI 1.47-2.12; P<0.001), respectively. CONCLUSIONS: Lower institutional case volume was associated with higher mortality after mitral valve repair. A minimum volume standard may be required for hospitals performing mitral valve repair to guarantee adequate outcome.

Addition of lysophosphatidic acid to mouse oocyte maturation media can enhance fertilization and developmental competence.

STUDY QUESTION: Does exposure to lysophosphatidic acid (LPA) during in vitro maturation (IVM) enhance the maturation and developmental competence of mouse oocytes? SUMMARY ANSWER: Supplementation of IVM medium with 30 µM LPA enhanced the developmental competence of in vitro matured oocytes and so made them more comparable to in vivo matured control oocytes. WHAT IS KNOWN ALREADY: LPA is a small phospholipid that acts as an extracellular signaling molecule by binding to and activating at least five G protein-coupled receptors. LPA has various biological actions, with both developmental and physiological effects. STUDY DESIGN, SIZE, DURATION: During IVM, LPA at six different doses (0, 1, 10, 30, 50 or 100 µM) was added into the TCM-199 medium. After maturation, the developmental competence and other parameters of the oocytes were assessed. PARTICIPANTS/MATERIALS, SETTING, METHODS: Immature GV stage oocytes from 5- to 6-week-old female BDF-1 mice were incubated for 17-18 h in IVM medium containing 0, 1, 10 or 30 µM LPA and then either fertilized in vitro with epididymal sperm, or assessed for spindle morphology, mitochondrial membrane potential (ΔΨm) or the mRNA expression of a meiotic checkpoint gene (Mad2), a microtubule structure gene (Hook1), two maternally derived genes (Mater and Hsf1) and an apoptosis-related gene (Caspase6). The fertilized embryos were grown in vitro to assess blastocyst-formation rates, differential cell counts and apoptosis. MAIN RESULTS AND THE ROLE OF CHANCE: Rates of maturation, fertilization and blastocyst formation and hatching were significantly higher in the 30 µM LPA-supplemented group (94.3, 96.3, 79.1 and 51.3%, respectively) than in the unsupplemented control (0 µM) group (80.5, 87.5, 61.3 and 37.8%, respectively) and more comparable to that of the in vivo matured oocytes (100, 96.5, 95.3 and 92.9%, respectively). LPA did not adversely affect mitochondrial activity, spindle integrity, blastocyst cell number, caspase positivity or Mad2 expression. Oocytes matured in 30 µM LPA had reduced Caspase6 expression, but Hook1, Mater and Hsf1 were up-regulated in all of the LPA-supplemented groups. LIMITATIONS, REASONS FOR CAUTION: Chromosomal aneuploidy in the resultant blastocysts and the production of normal pups were not assessed. Only mouse oocytes were assessed. WIDER IMPLICATIONS OF THE FINDINGS: Supplementation of IVM medium with 30 µM LPA may enhance the developmental competence of mouse oocytes without affecting apoptosis, spindle normalcy or mitochondrial integrity. STUDY FUNDING/COMPETING INTEREST(S): This study was supported by a research grant (02-2012-021) from the Seoul National University Bundang Hospital. The authors declare that they have no competing interests.

The Association Between Institutional Case Volume of Hematopoietic Stem Cell Transplantation and Mortality.

BACKGROUND: Hematopoietic stem cell transplantation (HSCT) is a complex, high-risk procedure with significant morbidity and mortality. The positive impact of higher institutional case volume on survival has been reported in various high-risk procedures. The association between annual institutional HSCT case volume and mortality was analyzed using the National Health Insurance Service database. METHODS: Data on 16,213 HSCTs performed in 46 Korean centers between 2007 and 2018 were extracted. Centers were divided into low- or high-volume centers using an average of 25 annual cases as the cut-off. Adjusted odds ratios (OR) for 1-year mortality after allogeneic and autologous HSCT were estimated using multivariable logistic regression. RESULTS: For allogeneic HSCT, low-volume centers (≤25 cases/y) were associated with higher 1-year mortality (adjusted OR 1.17, 95% CI 1.04-1.31, P = .008). However, low-volume centers did not show higher 1-year mortality (adjusted OR 1.03, 95% CI 0.89-1.19, P = .709) for autologous HSCT. Long-term mortality after HSCT was significantly worse in low-volume centers (adjusted hazard ratio [HR] 1.17, 95% CI, 1.09-1.25, P < .001 and adjusted HR 1.09, 95% CI, 1.01-1.17, P = .024, allogeneic and autologous HSCT, respectively) compared with high-volume centers. CONCLUSION: Our data suggest that higher institutional HSCT case volume seems to be associated with better short- and long-term survival.

Effect of trichostatin A on fertilization and embryo development during extended culture of mouse oocyte.

We performed this study to investigate the effect of histone deacetylase inhibition during extended culture of in vitro matured mouse oocytes. In vitro matured mouse (BDF1) oocytes were cultured in vitro for 6, 12, and 24 h, respectively, and then inseminated. During in vitro culture for 6 and 12 h, two doses of trichostatin A (TSA), a histone deacetylase inhibitor, were added (100 nM and 500 nM) to the culture medium and the oocytes were then inseminated. During the 24-h in vitro culture, two doses of TSA were added (100 nM and 500 nM) to the medium and the oocytes were activated with 10 mM SrCl2. After the 6-h culture, the fertilization rate was similar to that of the control group, but the blastocyst formation rate was significantly decreased. After the 12-h culture, both the fertilization and blastocyst formation rates were significantly decreased. After the 24-h culture, total fertilization failure occurred. In the oocytes cultured for 6 and 12 h, the fertilization and blastocyst formation rates did not differ between the TSA-supplemented and control groups. Although extended culture of the mouse oocytes significantly affected their fertilization and embryo development, TSA supplementation did not overcome their decreased developmental potential.

Institutional case volume and mortality after aortic and mitral valve replacement: a nationwide study in two Korean cohorts.

BACKGROUND: There are only a handful of published studies regarding the volume-outcome relationship in heart valve surgery. We evaluated the association between institutional case volume and mortality after aortic valve replacement (AVR) and mitral valve replacement (MVR). METHODS: Two separate cohorts of all adults who underwent AVR or MVR, respectively, between 2009 and 2016 were analyzed using a Korean healthcare insurance database. Hospitals performing AVRs were divided into three groups according to the average annual case volume: the low- (< 20 cases/year), medium- (20-70 cases/year), and high-volume centers (> 70 cases/year). Hospitals performing MVRs were also grouped as the low- (< 15 cases/year), medium- (15-40 cases/year), or high-volume centers (> 40 cases/year). In-hospital mortality after AVR or MVR were compared among the groups. RESULTS: In total, 7875 AVR and 5084 MVR cases were analyzed. In-hospital mortality after AVR was 8.3% (192/2318), 4.0% (84/2102), and 2.6% (90/3455) in the low-, medium-, and high-volume centers, respectively. The adjusted risk was higher in the low- (OR 2.31, 95% CI 1.73-3.09) and medium-volume centers (OR 1.53, 95% CI 1.09-2.15) compared to the high-volume centers. In-hospital mortality after MVR was 9.3% (155/1663), 6.3% (94/1501), and 2.9% (56/1920) in the low-, medium-, and high-volume centers, respectively. Compared to the high-volume centers, the medium- (OR 1.97, 95% CI 1.35-2.88) and low-volume centers (OR 2.29, 95% CI 1.60-3.27) showed higher adjusted risk of in-hospital mortality. CONCLUSIONS: Lower case volume is associated with increased in-hospital mortality after AVR and MVR. The results warrant a comprehensive discussion regarding regionalization/centralization of cardiac valve replacements to optimize patient outcomes.

Dose-dependent effect of sphingosine-1-phosphate in mouse oocyte maturation medium on subsequent embryo development.

AIM: To investigate the dose-dependent effect of sphingosine-1-phosphate (S1P) supplementation on meiotic maturation, apoptosis and developmental competence of immature mouse oocytes. METHODS: Immature oocytes from 5- to 6-week-old BDF1 mice were incubated in maturation medium containing S1P with six different doses (10 nM, 50 nM, 100 nM, 500 nM, 1 µM, and 2 µM) for 18-19 h. Fertilization and blastocyst formation was assessed. All blastocysts were stained by anti-caspase antibody. RESULTS: Treatment with 100 nM, 500 nM and 1 µM S1P showed significantly higher blastulation rate [66.0, 62.1 and 66.2%, respectively, p < 0.05 when compared with control (40.0%)]. Blastomere count was similar across six treatment groups, but the percentage of apoptotic blastomere was significantly lower in the 100 nM, 500 nM, and 2 µM S1P-treated groups [5.4, 6.5, and 3.7%, respectively, p < 0.05 when compared with control (10.6%)]. CONCLUSION: Considering the blastulation rate together with the apoptotic event in the blastocysts, adding 100 and 500 nM S1P within oocyte maturation medium could be beneficial in the development of immature mouse oocytes.

Effect of maturation on the expression of aquaporin 3 in mouse oocyte.

This study aimed to investigate whether aquaporin 3 (Aqp3) mRNAs are expressed in immature oocytes and altered during in vitro maturation process. Five- to 6-week-old female ICR mice were primed by gonadotropin for 24 and 48 h. Immature oocytes obtained 48 h after priming were also matured in vitro for 17 to 18 h. In vivo matured oocytes were obtained after 48 h priming followed by hCG injection. Total RNAs were extracted from 80 to 150 oocytes in each experimental group, and the levels of Aqp3 mRNA were quantified by real-time reverse transcriptase polymerase chain reaction. The experiments were repeated twice using different oocytes. The Aqp3 mRNA was expressed in immature oocytes, as well as in in vitro and in vivo matured oocytes. The expression level was higher in immature oocytes obtained 48 h after priming (17.2 ± 8.6, mean ± SD) than those with no priming (5.7 ± 0.8) or obtained 24 h after priming (2.5 ± 0.8). The expression of Aqp3 mRNA decreased after in vitro maturation (1.2 ± 0.5), which was similar to in vivo matured oocytes (1.0 ± 0.0). Our work demonstrated that Aqp3 mRNA expression increased during the development of immature oocyte but decreased after completion of in vitro maturation. The results indicate that AQP3 is certainly needed for the acquisition of immature oocytes' full growing potential within antral follicles.

Association between institutional case volume and mortality following thoracic aorta replacement: a nationwide Korean cohort study.

BACKGROUND: The inverse relationship between case volume and postoperative mortality following high-risk surgical procedures have been reported. Thoracic aorta surgery is associated with one of the highest postoperative mortality. The relationship between institutional case volume and postoperative mortality in patients undergoing thoracic aorta replacement surgery was evaluated. METHODS: All thoracic aorta replacement surgeries performed in Korea between 2009 and 2016 in adult patients were analyzed using an administrative database. Hospitals were divided into low (< 30 cases/year), medium (30-60 cases/year), or high (> 60 cases/year) volume centers depending on the annual average number of thoracic aorta replacement surgeries performed. The impact of case volume on in-hospital mortality was assessed using the logistic regression. RESULTS: Across 83 hospitals, 4867 cases of thoracic aorta replacement were performed. In-hospital mortality was 8.6% (191/2222), 10.7% (77/717), and 21.9% (422/1928) in high, medium, and low volume centers, respectively. The adjusted risk of in-hospital mortality was significantly higher in medium (odds ratio [OR], 1.56; 95% confidence interval [CI], 1.16-2.11, P = 0.004) and low volume centers (OR, 3.12; 95% CI, 2.54-3.85, P < 0.001) compared to high volume centers. CONCLUSIONS: Patients who had underwent thoracic aorta replacement surgery in lower volume centers had increased risk of in-hospital mortality after surgery compared to those in higher volume centers. Our results may provide the basis for minimum case volume requirement or regionalization in thoracic aorta replacement surgery for optimal patient outcome.

Exposing mouse oocytes to necrostatin 1 during in vitro maturation improves maturation, survival after vitrification, mitochondrial preservation, and developmental competence.

Necrostatin 1 (Nec1) is widely used in disease models to examine the contribution of receptor-interacting protein kinase 1 in cell death. The biological actions of Nec1 are blocking necrotic cell death. The purpose of this study was to investigate whether adding Nec1 into in vitro maturation (IVM) media, followed by vitrification procedures, could enhance the survival and developmental competency of oocytes. Germinal vesicle oocytes were matured in IVM medium containing 2 different doses of Nec1 (0.5 and 1 µmol/L). After IVM, the oocytes were vitrified using a 2-step exposure to equilibrium and vitrification solutions. After warming, the rates of survival, fertilization, embryonic development up to blastocyst in vitro, morphology of spindle and chromosome, membrane integrity, mitochondria integrity, and several gene expressions were evaluated. The survival and developmental competency of oocytes were higher in the 1 µmol/L Nec1-treated group than control. The proportion with intact spindles/chromosomes and stable membranes was similar in all the groups. The mitochondrial integrity of all Nec1-treated groups showed a higher score with strong staining. The 1 µmol/L Nec1 showed significantly increased expressions of Mad2, Gdf9, and Bcl2. The Cirp level had a tendency to be downregulated in the 0.5 µmol/L Nec1 but upregulated in the 1 µmol/L Nec1, compared with the control. The Mtgenome expressions were significantly decreased in both Nec1 groups. The supplementation of 1 µmol/L Nec1 into the IVM medium could be beneficial for the survival and development of immature oocytes after vitrification.

Closed vitrification of mouse oocytes using the CryoLogic vitrification method: A modification that improves developmental competence.

OBJECTIVE: To compare the mouse oocyte vitrification outcomes of the CryoLogic vitrification method (CVM) and the conventional open method using a Cryotop. Two CVM methods (original CVM and modified CVM) were tested. METHODS: Mature oocytes obtained from female BDF-1 mice were vitrified by two-step exposure to equilibrium and vitrification solutions. Three vitrification protocols were tested on three groups: the CVM-kit, modified CVM, and Cryotop groups. After exposure to the two solutions, the oocytes were vitrified. After warming, the oocytes were fertilized in vitro, and the embryo development was assessed. Blastomeres positive for caspase were counted using an in situ assay kit. The spindle morphology and chromosome configurations of warmed vitrified oocytes were also assessed. RESULTS: The modified CVM and Cryotop groups showed similar developmental capacities, and similar proportions of cells with intact spindles and chromosome configurations. The modified CVM protocol was superior to the original CVM protocol for developmental competence and intact spindle preservation. However, the CVM group showed a relatively higher number of apoptotic cells in blastocysts. CONCLUSION: Closed vitrification using the modified CVM protocol may be used as an alternative to the conventional open method, but strategies to decrease apoptosis in the blastomere need to be investigated.

The beneficial effects of antifreeze proteins in the vitrification of immature mouse oocytes.

Antifreeze proteins (AFPs) are a class of polypeptides that permit organismal survival in sub-freezing environments. The purpose of this study was to investigate the effect of AFP supplementation on immature mouse oocyte vitrification. Germinal vesicle-stage oocytes were vitrified using a two-step exposure to equilibrium and vitrification solution in the presence or absence of 500 ng/mL of AFP III. After warming, oocyte survival, in vitro maturation, fertilization, and embryonic development up to the blastocyst stage were assessed. Spindle and chromosome morphology, membrane integrity, and the expression levels of several genes were assessed in in vitro matured oocytes. The rate of blastocyst formation was significantly higher and the number of caspase-positive blastomeres was significantly lower in the AFP-treated group compared with the untreated group. The proportion of oocytes with intact spindles/chromosomes and stable membranes was also significantly higher in the AFP group. The AFP group showed increased Mad2, Hook-1, Zar1, Zp1, and Bcl2 expression and lower Eg5, Zp2, Caspase6, and Rbm3 expression compared with the untreated group. Supplementation of the vitrification medium with AFP has a protective effect on immature mouse oocytes, promoting their resistance to chilling injury. AFPs may preserve spindle forming ability and membrane integrity at GV stage. The fertilization and subsequent developmental competence of oocytes may be associated with the modulation of Zar1, Zp1/Zp2, Bcl2, Caspase6, and Rbm3.

Effect of antifreeze protein supplementation in vitrification medium on mouse oocyte developmental competence.

OBJECTIVE: To investigate the effect of antifreeze protein (AFP) supplementation during mouse oocyte vitrification on the survival, fertilization and embryonic development. DESIGN: Animal study. SETTING: University laboratory. ANIMAL(S): BDF-1 mice. INTERVENTION(S): In vivo-matured metaphase II oocytes were vitrified with the use of CryoTop by two-step exposure to equilibrium and vitrification solution supplemented or not with 500 ng/mL AFP III. MAIN OUTCOME MEASURE(S): Postwarming survival, fertilization, embryonic development up to blastocyst in vitro, morphology of spindle and chromosome, membrane integrity, adenosine triphosphate (ATP) contents, and several gene expressions. RESULT(S): In the AFP-treated group, blastocyst formation rate was significantly higher and blastomere count with positive caspase was significantly lower compared with the nontreated group. Rate of intact spindle/chromosome, stable membrane, and ATP contents were significantly higher in AFP group. AFP group showed higher Mad2 and lower Eg5 gene expression. Both vitrification groups showed increased Hsf1, Zar1, and Zp1/Zp2 expression and decreased Hook1 and Zp3 expression compared with fresh control samples. CONCLUSION(S): Supplementation of AFP in vitrification medium has a protective effect on mouse oocytes for chilling injury; it can preserve spindle/membrane integrity and intracellular ATP contents. More stable spindle integrity in the AFP group may be associated with higher Mad2 and lower Eg5 gene expression.