Nitrogen reduction by the Fe sites of synthetic [Mo3S4Fe] cubes.

Nitrogen (N2) fixation by nature, which is a crucial process for the supply of bio-available forms of nitrogen, is performed by nitrogenase. This enzyme uses a unique transition-metal-sulfur-carbon cluster as its active-site co-factor ([(R-homocitrate)MoFe7S9C], FeMoco)1,2, and the sulfur-surrounded iron (Fe) atoms have been postulated to capture and reduce N2 (refs. 3-6). Although there are a few examples of synthetic counterparts of the FeMoco, metal-sulfur cluster, which have shown binding of N2 (refs. 7-9), the reduction of N2 by any synthetic metal-sulfur cluster or by the extracted form of FeMoco10 has remained elusive, despite nearly 50 years of research. Here we show that the Fe atoms in our synthetic [Mo3S4Fe] cubes11,12 can capture a N2 molecule and catalyse N2 silylation to form N(SiMe3)3 under treatment with excess sodium and trimethylsilyl chloride. These results exemplify the catalytic silylation of N2 by a synthetic metal-sulfur cluster and demonstrate the N2-reduction capability of Fe atoms in a sulfur-rich environment, which is reminiscent of the ability of FeMoco to bind and activate N2.

Hyperchloremia Is Not an Independent Risk Factor for Postoperative Acute Kidney Injury in Pediatric Cardiac Patients.

OBJECTIVE: Hyperchloremia recently has been shown to have an association with the development of acute kidney injury (AKI) in critically ill patients. However, there is little information about the prevalence of an abnormal chloride concentration after pediatric cardiac surgery and its association with postoperative AKI. The aim of this study was to determine the prevalence of hyperchloremia and its association with AKI in pediatric patients after cardiac surgery. DESIGN: A retrospective single-center study. SETTING: Referral high-volume pediatric cardiac center in a tertiary teaching hospital. PARTICIPANTS: Patients under 72 months of age with congenital heart disease who underwent cardiac surgery with the use of cardiopulmonary bypass. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The primary outcome was development of AKI diagnosed by Kidney Disease Improving Global Outcomes consensus criteria. The associations of outcomes with the highest serum chloride concentration ([Cl-]max) and time-weighted average chloride concentration ([Cl-]ave) within the first 48 hours after surgery were investigated. Of 521 patients included in the study, 463 patients (88.9%) had hyperchloremia at least 1 time within the first 48 hours after surgery. Postoperative AKI occurred in 205 patients (39.3%). [Cl-]ave and [Cl-]max in the AKI group were significantly higher than those in the non-AKI group (112 [110-114] mEq/L v 111 [109-113] mEq/L, p = 0.001 and 116 [113, 119] mEq/L v 114 [112-118] mEq/L, p = 0.002, respectively). After adjustment for other predictors of AKI by multivariable analyses, neither [Cl-]ave nor [Cl-]max was associated independently with the development of AKI (odds ratio [OR] = 1.040, 95% confidence interval [CI]: 0.885-1.220, p = 0.63; OR = 0.992, 95% CI: 0.874-1.130. p = 0.90). CONCLUSION: Postoperative hyperchloremia was common and was associated with the development of AKI in pediatric patients after congenital cardiac surgery in univariate analysis. After adjustment for predictors of AKI by multivariate analyses, there was no significant relationship between postoperative chloride concentration and AKI.

High Ionized Calcium Concentration Is Associated With Prolonged Length of Stay in the Intensive Care Unit for Postoperative Pediatric Cardiac Patients.

OBJECTIVE: There has been controversy regarding the beneficial effects of calcium on myocardial contractility and the harmful effects on myocardial cells, especially in children. The aim of this study was to investigate an association between ionized calcium concentration (iCa) and outcomes for pediatric patients after cardiac surgery. DESIGN: A retrospective, single-center study from May 2013 to December 2014. SETTING: Referral high-volume pediatric cardiac center in a tertiary teaching hospital. PATIENTS: Patients <72 months old with congenital heart disease who underwent palliative or definitive surgery. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The association between pH-corrected iCa within 24 hours after surgery and intensive care unit (ICU) length of stay (ILOS) was defined as the primary outcome. The highest iCa (iCamax), lowest iCa (iCamin), and time-weighted average iCa (iCaave) were stratified and compared with the outcomes. The authors reviewed 5,468 ionized calcium measurements from 357 consecutive pediatric patients during the study period. One patient died at postoperative day 34 in the ICU. Significant differences in ILOS were observed among patients after cardiopulmonary bypass (CPB) according to iCaave, iCamax, and iCamin but not among patients without CPB. Patients with CPB and an iCaave value of 1.31-to-1.40 mmol/L, 1.41-to-1.50 mmol/L, 1.51-to-1.60 mmol/L, and >1.60 mmol/L stayed in the ICU for 7 (interquartile range [IQR] 4-10) days, 8 (IQR 6-16) days, 10 (IQR 8-14) days, and 19 (IQR 12-38) days, respectively, which was significantly longer than the ILOS of 5 (4-8) days for patients with an iCaave of 1.21-to-1.30 mmol/L. Even after adjustment for other predictors of ILOS using multivariable analyses, there were significant relationships of ILOS with iCaave and iCamin values of >1.50 mmol/L among patients with CPB. CONCLUSIONS: Higher iCa within 24 hours after congenital cardiac surgery using CPB was independently associated with longer LOS in the ICU.

General Anesthesia With Remimazolam During Minimally Invasive Cardiac Surgery for Atrial Septal Defect: A Pediatric Case Report.

Remimazolam is a new ultrashort-acting benzodiazepine sedative, the use of which has not been reported for pediatric cardiac surgery. This case report describes the use of remimazolam in a 6-year-old girl who underwent minimally invasive cardiac surgery with right-sided thoracotomy for an atrial septal defect. Under electroencephalographic monitoring, remimazolam (2-4 mg kg-1 h-1) and remifentanil (0.05 µg kg-1 min-1) were administered with an intercostal nerve block during the procedure. The patient awoke and was extubated promptly after surgery, without any serious adverse events, including intraoperative awareness. Remimazolam may be a viable option for general anesthesia during pediatric cardiac surgery.

Prophylactic endoscopic transpapillary gallbladder stenting to prevent acute cholecystitis induced after metallic stent placement for malignant biliary strictures: a retrospective study in Japan.

BACKGROUND/AIMS: Endoscopic biliary drainage using self-expandable metallic stents (SEMSs) for malignant biliary strictures occasionally induces acute cholecystitis (AC). This study evaluated the efficacy of prophylactic gallbladder stents (GBS) during SEMS placement. METHODS: Among 158 patients who underwent SEMS placement for malignant biliary strictures between January 2018 and March 2023, 30 patients who attempted to undergo prophylactic GBS placement before SEMS placement were included. RESULTS: Technical success was achieved in 21 cases (70.0%). The mean diameter of the cystic duct was more significant in the successful cases (6.5 mm vs. 3.7 mm, p<0.05). Adverse events occurred for 7 patients (23.3%: acute pancreatitis in 7; non-obstructive cholangitis in 1; perforation of the cystic duct in 1 with an overlap), all of which improved with conservative treatment. No patients developed AC when the GBS placement was successful, whereas 25 of the 128 patients (19.5%) without a prophylactic GBS developed AC during the median follow-up period of 357 days (p=0.043). In the multivariable analysis, GBS placement was a significant factor in preventing AC (hazard ratio, 0.61; 95% confidence interval, 0.37-0.99; p=0.045). CONCLUSIONS: GBS may contribute to the prevention of AC after SEMS placement for malignant biliary strictures.

Plain computed tomography for differentiating neoplastic and non-neoplastic pedunculated gallbladder polyps.

AIMS: Surgery is recommended for large pedunculated gallbladder polyps (PGPs), which measure 10 mm or more in size, because they tend to be neoplastic polyps (NPs), such as adenomas and adenocarcinomas. However, after resection, they are often found to be non-neoplastic polyps (non-NPs). This study aimed to evaluate the usefulness of plain CT in distinguishing NPs from non-NPs. METHODS: Of the 80 patients who underwent cholecystectomy for PGPs ( 10 mm between January 2008 and February 2021, 46 who underwent plain and contrast-enhanced CT (CE-CT) before resection were included in this study. We retrospectively assessed the polyp detection rate (PDR) using CT and calculated the difference in the CT values between PGPs and the surrounding bile. RESULTS: Twenty-one patients had NPs (12 adenomas, 5 carcinomas in adenoma, and 4 adenocarcinomas). The others were non-NPs (24 cholesterol polyps and one hyperplastic polyp). The PDR using plain CT was significantly higher in the NP group than in the non-NP group (38% (8/21) vs. 0% (0/25), p <0.01). The sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of NPs were 38%, 100%, 100%, 66%, and 72%, respectively. The difference in the CT values between PGPs and the surrounding bile was significantly larger in the NP group than in the non-NP group (14.12 ± 11.38 HU, 5.04 ± 6.15 HU, p <0.01). CONCLUSIONS: PGPs detected using plain CT had a high probability of being NPs. Plain CT is therefore considered to be useful for differentiating NPs from non-NPs.

Loop technique for guidewire manipulation during endoscopic ultrasound-guided hepaticogastrostomy.

Background and Aim: Endoscopic ultrasound-guided hepaticogastrostomy (EUS-HGS) is widely used in the management of biliary obstructions; however, literature on guidewire manipulation is lacking. This study aimed to assess the utility and optimal conditions of the loop technique for guidewire manipulation during EUS-HGS. Methods: Consecutive patients who underwent EUS-HGS between April 2015 and January 2022 were included in this study. Patient characteristics and procedural details were retrospectively analyzed. Guidewire manipulations were classified as conventional technique or loop technique, based on the shape of the guidewire tip. Results: A total of 52 patients (Median age: 73 years, 38 male and 14 female) underwent EUS-HGS. The median guidewire insertion time was 49 s and the median overall procedure time was 20.5 min. The initial guidewire direction was toward the peripheral side in 23 patients (44%). Technical success rate of the EUS-HGS was 100%. Twenty patients (38%) underwent the procedure using the loop technique and 32 (62%) with the conventional technique. In the logistic regression analysis, an angle between the bile duct and needle of >70° was independently associated with use of the loop technique (OR 9.84; 95% CI: 2.24-43.13; P <0.01). Conclusion: This study revealed the utility of the loop technique in EUS-HGS. This technique is recommended if the bile duct is punctured at an angle >70°.