Theoretical Study on the C-H Activation of Methane by Liquid Metal Indium: Catalytic Activity of Small Indium Clusters.

The mechanism of C-H activation of methane by liquid indium, which is the first step of the dehydrogenative conversion of methane to higher hydrocarbons, was investigated using density functional theory calculations. In the first-principle molecular dynamics trajectory at the experimental temperature (1200 K), low-coordinated indium atoms continuously appear on the disordered liquid surface. The C-H cleavage is endothermic on clean surfaces, while the low-coordinated indium atoms reduce the endothermicity significantly. In small indium clusters, which are models of low-coordinated atoms on a surface, the calculated activation energy is much smaller than that on the clean surface. The energy level of the methane C-H σ* orbital is reduced by the interaction with the indium 5pσ orbitals. In2 shows the lowest activation energy and exothermicity in the C-H bond cleavage.

Ability of minimally invasive surgery to decrease incisional surgical site infection occurrence in patients with colorectal cancer and other gastroenterological malignancies.

Background: Surgical site infection (SSI) is one of the most important complications of surgery for gastroenterological malignancies because it leads to a prolonged postoperative hospital stay and increased inpatient costs. Furthermore, SSI can delay the initiation of postoperative treatments, including adjuvant chemotherapy, negatively affecting patient prognosis. Identifying the risk factors for SSI is important to improving intra- and postoperative wound management for at-risk patients. Methods: Patients with gastroenterological malignancies who underwent surgery at our institution were retrospectively reviewed and categorized according to the presence or absence of incisional SSI. Clinicopathological characteristics such as age, sex, body mass index, malignancy location, postoperative blood examination results, operation time, and blood loss volume were compared between groups. The same analysis was repeated of only patients with colorectal malignancies. Results: A total of 528 patients (330 men, 198 women; mean age, 68 ± 11 years at surgery) were enrolled. The number of patients with diseases of the esophagus, stomach, small intestine, colon and rectum, liver, gallbladder, and pancreas were 25, 150, seven, 255, 51, five, and 35, respectively. Open surgery was performed in 303 patients vs. laparoscopic surgery in 225 patients. An incisional SSI occurred in 46 patients (8.7%). Multivariate logistic regression analysis showed that postoperative hyperglycemia (serum glucose level ≥140 mg/dl within 24 h after surgery), colorectal malignancy, and open surgery were independent risk factors for incisional SSI. In a subgroup analysis of patients with colorectal malignancy, incisional SSI occurred in 27 (11%) patients. Open surgery was significantly correlated with the occurrence of incisional SSI (P = 0.024). Conclusions: Postoperative hyperglycemia and open surgery were significant risk factors for SSI in patients with gastroenterological malignancies. Minimally invasive surgery could reduce the occurrence of incisional SSI.

Clinical impact of lymphocyte/C-reactive protein ratio on postoperative outcomes in patients with rectal cancer who underwent curative resection.

Cancer-related systemic inflammation influences postoperative outcomes in cancer patients. Although the relationship between inflammation-related markers and postoperative outcomes have been investigated in many studies, their clinical significance remains to be elucidated in rectal cancer patients. We focused on the lymphocyte count/C-reactive protein ratio (LCR) and its usefulness in predicting short- and long-term outcomes after rectal cancer surgery. Patients with rectal cancer who underwent curative resection at our institution between 2010 and 2018 were enrolled in this study. We comprehensively compared the effectiveness of 11 inflammation-related markers, including LCR and other clinicopathological characteristics, in predicting postoperative complications and survival. Receiver operating characteristic curve analysis indicated that LCR had the highest area under the curve value for predicting the occurrence of postoperative complications. In the multivariate analysis, male sex (odds ratio [OR]: 2.21, 95% confidence interval [CI] 1.07-4.57, P = 0.031), low tumor location (OR: 2.44, 95% CI 1.23-4.88, P = 0.011), and low LCR (OR: 3.51, 95% CI 1.63-7.58, P = 0.001) were significantly and independently associated with the occurrence of postoperative complications. In addition, multivariate analysis using Cox's proportional hazard regression model for the prediction of survival showed that low LCR (≤ 12,600) was significantly associated with both poor overall survival (hazard ratio [HR]: 2.07, 95% CI 1.03-4.15, P = 0.041) and recurrence-free survival (HR: 2.21, 95% CI 1.22-4.01, P = 0.009). LCR is a useful marker for predicting both short- and long-term postoperative outcomes in rectal cancer patients who underwent curative surgery.

Catalytic Mechanism of Liquid-Metal Indium for Direct Dehydrogenative Conversion of Methane to Higher Hydrocarbons.

There is a great interest in direct conversion of methane to valuable chemicals. Recently, we reported that silica-supported liquid-metal indium catalysts (In/SiO2) were effective for direct dehydrogenative conversion of methane to higher hydrocarbons. However, the catalytic mechanism of liquid-metal indium has not been clear. Here, we show the catalytic mechanism of the In/SiO2 catalyst in terms of both experiments and calculations in detail. Kinetic studies clearly show that liquid-metal indium activates a C-H bond of methane and converts methane to ethane. The apparent activation energy of the In/SiO2 catalyst is 170 kJ mol-1, which is much lower than that of SiO2, 365 kJ mol-1. Temperature-programmed reactions in CH4, C2H6, and C2H4 and reactivity of C2H6 for the In/SiO2 catalyst indicate that indium selectively activates methane among hydrocarbons. In addition, density functional theory calculations and first-principles molecular dynamics calculations were performed to evaluate activation free energy for methane activation, its reverse reaction, CH3-CH3 coupling via Langmuir-Hinshelwood (LH) and Eley-Rideal mechanisms, and other side reactions. A qualitative level of interpretation is as follows. CH3-In and H-In species form after the activation of methane. The CH3-In species wander on liquid-metal indium surfaces and couple each other with ethane via the LH mechanism. The solubility of H species into the bulk phase of In is important to enhance the coupling of CH3-In species to C2H6 by decreasing the formation of CH4 though the coupling of CH3-In species and H-In species. Results of isotope experiments by combinations of CD4, CH4, D2, and H2 corresponded to the LH mechanism.

Essential role of Cav3.2 T-type calcium channels in butyrate-induced colonic pain and nociceptor hypersensitivity in mice.

Given the role of Cav3.2 isoform among T-type Ca2+ channels (T-channels) in somatic and visceral nociceptive processing, we analyzed the contribution of Cav3.2 to butyrate-induced colonic pain and nociceptor hypersensitivity in mice, to evaluate whether Cav3.2 could serve as a target for treatment of visceral pain in irritable bowel syndrome (IBS) patients. Mice of ddY strain, and wild-type and Cav3.2-knockout mice of a C57BL/6J background received intracolonic administration of butyrate twice a day for 3 days. Referred hyperalgesia in the lower abdomen was assessed by von Frey test, and colonic hypersensitivity to distension by a volume load or chemicals was evaluated by counting nociceptive behaviors. Spinal phosphorylated ERK was detected by immunohistochemistry. Cav3.2 knockdown was accomplished by intrathecal injection of antisense oligodeoxynucleotides. Butyrate treatment caused referred hyperalgesia and colonic hypersensitivity to distension in ddY mice, which was abolished by T-channel blockers and/or Cav3.2 knockdown. Butyrate also increased the number of spinal phosphorylated ERK-positive neurons following colonic distension in the anesthetized ddY mice. The butyrate-treated ddY mice also exhibited T-channel-dependent colonic hypersensitivity to intracolonic Na2S, known to enhance Cav3.2 activity, and TRPV1, TRPA1 or proteinase-activated receptor 2 (PAR2) agonists. Wild-type, but not Cav3.2-knockout, mice of a C57BL/6J background, after treated with butyrate, mimicked the T-channel-dependent referred hyperalgesia and colonic hypersensitivity in butyrate-treated ddY mice. Our study provides definitive evidence for an essential role of Cav3.2 in the butyrate-induced colonic pain and nociceptor hypersensitivity, which might serve as a target for treatment of visceral pain in IBS patients.