Photocatalytic CO2 Reduction Using Ti3C2Xy (X = Oxo, OH, F, or Cl) MXene-ZrO2: Structure, Electron Transmission, and the Stability.

CO2 photoreduction using a semiconductor-based photocatalyst is a promising option for completing a new carbon-neutral cycle. The short lifetime of charges generated owing to light energy is one of the most critical problems in further improving the performance of semiconductor-based photocatalysts. This study shows the structure, electron transmission, and stability of Ti3C2Xy (X = oxo, OH, F, or Cl) MXene combined with a ZrO2 photocatalyst. Using H2 as a reductant, the photocatalytic CO formation rate increased by 6.6 times to 4.6 µmol h-1 gcat-1 using MXene (3.0 wt %)-ZrO2 compared to that using ZrO2, and the catalytic route was confirmed using 13CO2 to form 13CO. In clear contrast, using H2O (gas) as a reductant, CH4 was formed as the major product using Ti3C2Xy MXene (5.0 wt %)-ZrO2 at the rate of 3.9 µmol h-1 gcat-1. Using 13CO2 and H2O, 12CH4, 12C2H6, and 12C3H8 were formed besides H212CO, demonstrating that the C source was the partial decomposition and hydrogenation of Ti3C2Xy. Using the atomic force and high-resolution electron microscopies, 1.6 nm thick Ti3C2Xy MXene sheets were observed, suggesting ∼3 stacked layers that are consistent with the Ti-C and Ti···Ti interatomic distances of 0.218 and 0.301 nm, respectively, forming a [Ti6C] octahedral coordination, and the major component as the X ligand was suggested to be F and OH/oxo, with the temperature increasing by 116 K or higher owing to the absorbed light energy, all based on the extended X-ray absorption fine structure analysis.

Exchange of CO2 with CO as Reactant Switches Selectivity in Photoreduction on Co-ZrO2 from C1-3 Paraffin to Small Olefins.

Photocatalytic reduction of CO2 into C2,3 hydrocarbons completes a C-neutral cycle. The reaction pathways of photocatalytic generation of C2,3 paraffin and C2H4 from CO2 are mostly unclear. Herein, a Co0-ZrO2 photocatalyst converted CO2 into C1-3 paraffin, while selectively converting CO into C2H4 and C3H6 (6.0 ± 0.6 µmol h-1 gcat-1, 70 mol%) only under UV-visible light. The photocatalytic cycle was conducted under 13CO and H2, with subsequent evacuation and flushing with CO. This iterative process led to an increase in the population of C2H4 and C3H6 increased up to 61-87 mol%, attributed to the accumulation of CH2 species at the interface between Co0 nanoparticles and the ZrO2 surface. CO2 adsorbed onto the O vacancies of the ZrO2 surface, with resulting COH species undergoing hydrogenation on the Co0 surface to yield C1-3 paraffin using either H2 or H2O (g, l) as the reductant. In contrast, CO adsorbed on the Co0 surface, converted to HCOH species, and then split into CH and OH species at the Co and O vacancy sites on ZrO2, respectively. This comprehensive study elucidates intricate photocatalytic pathways governing the transformation of CO2 into paraffin and CO to olefins.

Even a partial pathological response is associated with lower relapse rates in patients with operable rectal cancer undergoing neoadjuvant chemotherapy.

BACKGROUND: Neoadjuvant chemotherapy to treat locally advanced rectal cancer is an effective therapeutic strategy for the prevention of local recurrence and distant organ metastasis after surgery. OBJECTIVES: To assess the prognostic significance of histopathological tumor response in rectal cancer patients undergoing neoadjuvant chemotherapy. METHODS: This study included patients with operable rectal cancer who received neoadjuvant chemotherapy using the FOLFOX regimen (5-fluorouracil, l-leucovorin, and oxaliplatin) in a hospital between February 2012 and November 2017. The main outcome measure was disease-free survival with respect to histopathological response to neoadjuvant chemotherapy in resected specimens. RESULTS: The median follow-up was 32 months. Of 48 patients treated with neoadjuvant FOLFOX, 24 (50%) were classified as responders, which included two patients with pathological complete response and 22 patients with partial response. The remaining 24 patients (50%) were classified as nonresponders. Responders had a significantly better 3-year disease-free survival than nonresponders (86% vs. 62%, p = .02). CONCLUSIONS: Patients whose surgical specimens show a pathological complete response or partial response have good oncologic outcomes.

Oxaliplatin-induced increase in splenic volume: experiences from multicenter study in Japan.

BACKGROUND: Chemotherapy with oxaliplatin is known to induce sinusoidal obstruction syndrome (SOS). In a previous single-center study, we reported that oxaliplatin-induced increase in splenic volume (SV) is strongly indicative of SOS, and that this increase in SV persisted for > 1 year after completing chemotherapy. The aim of this study was to confirm the oxaliplatin-induced SV change in a multicenter study in patients with stage III colon cancer in Japan. METHODS: We enrolled 59 patients who underwent curative resection for stage III colon cancer in the FACOS study in a phase II multi-center clinical study. Participants received mFOLFOX6 or CAPOX as adjuvant chemotherapy. SV change was assessed three times by computed tomographic volumetry: before surgery, on completion of adjuvant chemotherapy, and 1 year after completing adjuvant chemotherapy. RESULTS: SV on completing and 1 year after chemotherapy was significantly higher than that before surgery (P < 0.001). Oxaliplatin-induced SOS persisted for > 1 year after the completion of adjuvant chemotherapy in half of the patients. There was no difference in 3-year disease-free survival with respect to the presence or absence of increased SV. An increase in SV was observed in 72% of patients treated with mFOLFOX6 and 94% of patients treated with CAPOX (P = 0.13). CONCLUSION: This study can be verified the findings observed in our previous single-center study, oxaliplatin-based adjuvant chemotherapy was associated with an increase in SV. Furthermore, this increase can persist for > 1 year. The continuous presence of SOS may have a negative impact on prognosis in patients that develop recurrent disease.

Determination and analysis of singlet oxygen quantum yields of talaporfin sodium, protoporphyrin IX, and lipidated protoporphyrin IX using near-infrared luminescence spectroscopy.

In photodynamic therapy (PDT), singlet oxygen ([Formula: see text]) is the main species responsible for promoting tumor cell death. The determination of the quantum yield (ΦΔ) of a photosensitizer (PS) is important for dosimetry. The purpose of this paper is to quantify the [Formula: see text] generated by the PS by near-infrared spectroscopy (NIRS). The ΦΔ of different PS species were measured by the detection of near-infrared [Formula: see text] luminescence. From the measurement results, the ΦΔ of talaporfin sodium, protoporphyrin IX (PpIX), and lipidated PpIX (PpIX lipid) were measured as 0.53, 0.77, and 0.87, respectively. In addition, the ΦΔ values of PpIX in a hypoxic and oxic solution were evaluated, since tumors are associated with regions of hypoxia. The measured ΦΔ indicated a same value at high (DO: 20%) and low (DO: 1%) oxygen concentrations. Using the measured ΦΔ, the amount of [Formula: see text] generated by the PSs was estimated using [[Formula: see text]] = D*ΦΔ, where D* is the total excited PS concentration. The generated [Formula: see text] amounts were little different at the high and the low oxygen concentrations, and the generated [Formula: see text] amount for each PS was different depending on each ΦΔ. The NIRS measurement determined the ΦΔ of talaporfin sodium, PpIX, and PpIX lipid. The quantitative evaluation based on the measured ΦΔ will support the development of PDT treatment monitoring and design.

[A Case of Peritoneal Dissemination of Colorectal Cancer in Which Conversion Surgery Could Be Performed after Reduction with CAPOX/Bevacizumab].

A woman in her 60s underwent lower endoscopy due to a positive fecal occult blood test. A type 2 tumor was found in the cecum, and a biopsy resulted in the diagnosis of adenocarcinoma(tub2). Contrast-enhanced CT showed an enlarged paracolonic lymph node but no distant metastasis, so the patient underwent a laparoscopic-assisted ileocolic resection and D3 lymph node dissection for cecum cancer. The pathology was pT3, pN2b, pM0, pStage Ⅲc, and 12 courses of FOLFOX were administered as adjuvant chemotherapy. Twenty-four months after the completion of adjuvant chemotherapy, an elevated CEA was observed, and a PET-CT was performed, which showed multiple peritoneal disseminated nodules with FDG accumulation. Based on this finding, CAPOX/bevacizumab therapy was introduced, and on completion of 4 courses, the PET-CT showed a decrease in the size of the nodules and the disappearance of FDG accumulation. Based on this, the patient underwent resection. A peritoneal dissemination resection and bilateral ovariectomy were laparoscopically performed, and the patient is currently under observation. In patients with metastatic recurrence of peritoneal dissemination who underwent complete resection, treatment with CAPOX/bevacizumab may allow for disease control and provide a long-term prognosis.

Analysis of colorectal cancer-related mutations by liquid biopsy: Utility of circulating cell-free DNA and circulating tumor cells.

We recruited 56 colorectal cancer patients and compared the mutational spectrum of tumor tissue DNA, circulating cell-free DNA (ccfDNA) and circulating tumor cell (CTC) DNA (ctcDNA) to evaluate the potential of liquid biopsy to detect heterogeneity of cancer. Tumor tissue DNA, ccfDNA, and ctcDNA were extracted from each patient and analyzed using next-generation sequencing (NGS) and digital PCR. To maximize yields of CTC, three antibodies were used in the capture process. From 34 untreated patients, 53 mutations were detected in tumor tissue DNA using NGS. Forty-seven mutations were detected in ccfDNA, including 20 not detected in tissues. Sixteen mutations were detected in ctcDNA, including five not detected in tissues. In 12 patients (35.3%), mutations not found in tumor tissues were detected by liquid biopsy: nine (26.5%) in ccfDNA only and three (8.8%) in ctcDNA only. Combination analysis of the two liquid biopsy samples increased the sensitivity to detect heterogeneity. From 22 stage IV patients with RAS mutations in their primary tumors, RAS mutations were detected in 14 (63.6%) ccfDNA and in eight (36.4%) ctcDNA using digital PCR. Mutations not detected in primary tumors can be identified in ccfDNA and in ctcDNA, indicating the potential of liquid biopsy in complementing gene analysis. Combination analysis improves sensitivity. Sensitivity to detect cancer-specific mutations is higher in ccfDNA compared with ctcDNA.

Establishment and characterization of a novel neuroendocrine carcinoma cell line derived from a human ascending colon tumor.

The incidence of rare neuroendocrine tumors (NET) is rapidly increasing. Neuroendocrine carcinoma (NEC) is a NET with poorly differentiated histological features, high proliferative properties and associated poor prognoses. As these carcinomas are so rare and, thus, affect only a small number of patients allowing for few cell lines to be derived from patient biopsies, the histological, immunohistochemical, and clinical characteristics associated with colorectal NEC and NEC in other organs have yet to be clearly defined. Herein, we describe the establishment of a novel NEC cell line (SS-2) derived from a tumor resection of the ascending colon from a 59-year-old Japanese woman. The histological, electron microscopic and immunohistochemical features of chromogranin A (CgA) as well as confirmation of synaptophysin positivity in this tumor were typical of those commonly observed in surgically resected colorectal NEC. Further, the Ki-67 labeling index of the resected tumor was >20% and, thus, the tumor was diagnosed as an NEC of the ascending colon. The SS-2 cell line maintained characteristic features to those of the resected tumor, which were further retained following implantation into subcutaneous tissues of nude mice. Additionally, when SS-2 cells were seeded into ultra-low attachment plates, they formed spheres that expressed higher levels of the cancer stem cell (CSC) marker CD133 compared to SS-2 cells cultured under adherent conditions. SS-2 cells may, therefore, contribute to the current knowledge on midgut NEC biological function while providing a novel platform for examining the effects of colorectal NEC drugs, including CSC.

Liquid Biopsy for the Management of Patients with Colorectal Cancer.

BACKGROUND: Liquid biopsy is a collective term that refers to the analysis of tumor-derived biomarkers isolated from biological fluids of cancer patients. Recently, many authors reported the usefulness of liquid biopsy for the management of malignancy. Summary and Key Messages: The peripheral blood of cancer patients is a pool of cells and/or cell products derived from the primary or metastatic tumor, including circulating tumor cells (CTCs), circulating free (cf) DNA or RNA, and exosomes containing proteins, nucleic acids, and lipids. CTCs are tumor cells that can be isolated from peripheral blood. Free circulating DNA with a tumor-specific mutation is called circulating tumor DNA (ctDNA). Some patients who undergo curative surgery experience recurrent disease, which can be due to the presence of minimal residual disease (MRD). Thus, MRD indicates a high risk of relapse. Detection of ctDNA or CTC after surgery is a direct proof of MRD. Molecular volume (e.g., the number of CTCs and level of ctDNA) might reflect tumor burden, thus high molecular volume may indicate poor prognosis. The most notable application of liquid biopsy in cancer is to understand spatial and temporal heterogeneities. Heterogeneity is one of the causes of refractoriness and hampers prediction of chemotherapeutic effect. Emerging mutations that are not present in primary tumors but are found in their metastases can be detected in ctDNA. Some colorectal cancer patients with wild-type RAS do not respond to epidermal growth factor receptor blockade. In a subset of these patients, RAS mutation is detected in ctDNA, indicating heterogeneity.

In Vivo Study on Mechanism Underlying Increased Pharmacological Effects of Phenobarbital in Rats with Glycerol-Induced Acute Renal Failure.

The mechanism underlying the increased pharmacological effects of phenobarbital in rats with glycerol-induced acute renal failure (ARF) was examined. In the experiments, a surgical cannula was inserted in the lateral ventricle of the rats for phenobarbital infusion, and the ARF induction was performed by intramuscular administration of 50% glycerol. The onset time of anesthesia by phenobarbital was determined with the tail flick method. In addition, cerebral microsomes were prepared from excised cerebral cortices of sham and ARF rats, and the cerebral expression of the γ-aminobutyric acid (GABA)A receptor and two cation-chloride transporters, KCC2 and NKCC1, was evaluated by Western blotting, as their functions are involved in the anesthetic effects of phenobarbital. When phenobarbital was infused in the ventricle, anesthesia was induced 2.2-times faster in ARF rats than in sham rats, and there was no detectable increase in the cerebral expression of the GABAA receptor in ARF rats. It was additionally noted that the cerebral expression of KCC2 decreased, whereas that of NKCC1 was unaltered in ARF rats. These findings indicated that the anesthetic effects of phenobarbital are potentiated in ARF rats, probably due to imbalanced cerebral expression of KCC2 and NKCC1, suggesting that altered cation-chloride handling in nerve cells is associated.

[Effectiveness of Chemoradiotherapy for the Treatment of Local Recurrence in Rectal Cancer-A Case Report].

Chemoradiotherapy(CRT)for locally recurrent rectal cancer can shrink the tumor and permit R0 resection; however, its effectiveness and safety have not been established. Herein, we report a case of a 60s man with locally recurrent rectal cancer invading the surrounding organs who was administered CRT followed by R0 laparoscopic-assisted abdominoperineal resection( APR). Local recurrence was detected 11 months after laparoscopic-assisted low anterior resection(pT3N0M0, pStage Ⅱ). After tumor shrinkage by CRT(capecitabine 3,000mg/day plus 45 Gy/25 Fr), laparoscopic-assisted APR was performed. The pathological findings showed a pathological complete response(pCR). The patient had not experienced recurrent disease at 6 months after the second surgery. CRT may improve the prognosis of patients with locally recurrent rectal cancer, especially those with possibly unresectable tumors.

[Consideration for Prognostic Indicators of Ovarian Metastasis of Colorectal Cancer].

Ovarian metastasis of colorectal cancer is associated with poor prognosis. Recent advances in chemotherapy may improve this prognosis. In this retrospective study, we evaluated indicators of poor prognosis for ovarian metastasis of colorectal cancer. Twenty patients, who were diagnosed with ovarian metastasis of colorectal cancer from April 2000 to December 2017, were enrolled. Oophorectomy was performed in 18 of the 20 patients. Postoperative chemotherapy was provided to 13 patients, and molecular targeting agents were administered in 5 patients. Metastases to other organs besides the ovaries, premenopausal condition, undifferentiated histologic type of the primary tumor, and no resection of ovarian metastases were identified as indicators of poor prognosis. The 3-year survival rate was 15%, and the 5-year survival rate was 0%. In conclusion, oophorectomy can improve the prognosis of patients with ovarian metastasis of colorectal cancer. However, prognostic improvement due to molecular target agents was not shown.

Male sex and history of ischemic heart disease are major risk factors for anastomotic leakage after laparoscopic anterior resection in patients with rectal cancer.

BACKGROUND: Anastomotic leakage (AL) is the most serious and common complication of surgery for rectal cancer, and associated risk factors remain unknown despite developments in laparoscopic surgery. The present study aimed to determine risk factors for AL after laparoscopic anterior resection (AR) of rectal cancer. METHODS: This retrospective cohort study extracted information from a prospective database of all consecutive colorectal resections that proceeded at Nippon Medical School Hospital between January 2011 and December 2015 (n = 865). We identified 154 patients with rectal cancer treated by elective laparoscopic AR with anastomosis using primary double-stapling. Clinical variables and comorbidity, habits, and surgery-related variables were assessed by univariate and multivariate analyses to determine preoperative risk factors for clinical AL. RESULTS: The overall rate of clinical AL was 11.7% (18 of 154 patients), and 5 (27.8%) of 18 patients required revised laparotomy. Data from males were analyzed because AL occurred only in males. Univariate analysis of male patients (n = 100) significantly associated preoperative creatinine values (p = 0.03) and a history of ischemic heart disease (IHD) (p = 0.012) with AL. The frequency of AL tended to increase (p = 0.06) when patients had low AR (p = 0.06) and transanal drainage. Having AL significantly prolonged hospital stays compared with patients without leakage (36.2 vs. 11.1 days; p <  0.01). Multivariate analysis identified a history of IHD (odds ratio [OR], 4.73; 95% confidence interval [CI], 1.27-17.5; p = 0.025] as an independent risk factor for AL. CONCLUSIONS: Male sex and a history of IHD are possible risk factors for AL after elective laparoscopic rectal cancer surgery.

Oxaliplatin-induced increase in splenic volume; irreversible change after adjuvant FOLFOX.

BACKGROUND AND OBJECTIVES: Oxaliplatin can cause hepatic sinusoidal obstruction syndrome (SOS). SOS can cause chemotherapy-related adverse effects or morbidity after liver resection. Conventionally, SOS is diagnosed using liver biopsy. Recently, it was reported that increased splenic volume (SV) can be used to detect SOS. In this study, we evaluated the changes in SV during adjuvant chemotherapy. METHODS: We enrolled 103 consecutive patients with stage III and high-risk stage II colorectal cancer treated with mFOLFOX6 (n = 37) or oral fluorouracil and leucovorin (n = 66) after curative surgery. SV was measured three times; pre-operatively, after chemotherapy, and 1 year after chemotherapy. RESULTS: SV was higher after mFOLFOX6 (median 135.89 mL) than pre-operatively (105.75 mL) (P < 0.001); SV at 1-year after finishing mFOLFOX6 (114.16 mL) returned to the same level as before surgery (P = 0.0015). SV increased in 28 patients (75.7%) treated with mFOLFOX6 (95%CI, 61.8-89.5), but had not recovered in 12 of these cases (42.9%) 1 year after finishing treatment (95%CI, 17.3-47.5). In contrast, oral fluorouracil and leucovorin did not change SV. CONCLUSIONS: SV increased after adjuvant mFOLFOX6, and had not recovered in almost half of cases 1-year after finishing chemotherapy. This increase may indicate continuous SOS, which can adversely affect treatment after recurrence.

[Obstructive Colon Cancer with Triple-Vessel Coronary Artery Disease - A Case Report].

The patient was a 70-year-old woman who was diagnosed with obstructive transverse colon cancer suspected of invading the abdominal wall by abdominal CT imaging. Since the preoperative electrocardiogram showed an ischemic change, echocardiography and coronary angiography were performed. We diagnosed chronic heart failure and angina pectoris because echocardiography showed low cardiac function(left ventricular ejection fraction; LVEF 37%)and coronary angiography indicated triple-vessel disease. We firstly performed coronary artery bypass graft surgery following self-expanding metallic stent placement as a bridge to surgery(BTS), because we judged this patient as a perioperative high-risk case. After improvement of cardiac function(LVEF 49%), expanded right hemicolectomy with partial resection of abdominal wall could be performed without perioperative complications. Colonic stenting as a BTS allowed us to treat comorbidities properly, and perform a radical surgery safely for such a high-risk patient.

[A case of Parkinson's disease with marked head drop after administration of donepezil hydrochloride].

A 76-year-old woman with a 2-year history of Parkinson's disease presented with dropped head, which had developed rapidly after she had been prescribed donepezil hydrochloride (DNP) at 3 |mg/day. After one month of medication, the extent of the head drop reached 90°. Examination revealed hypertrophy of the left sternocleidomastoid muscle, but no weakness of the extensor muscles in the cervical region. Surface electromyography demonstrated co-|contraction of the sternocleidomastoid and splenius capitus muscles during head flexion and extension. DNP was withdrawn, resulting in immediate amelioration of the head drop, and complete resolution was achieved after two months. Although head drop is often seen in patients with Parkinson's disease, few previous reports have documented DNP as a causative factor. If patients with Parkinson's disease develop head drop, it is important to investigate any history of DNP medication.

Effect of sterol composition on the activity of the yeast G-protein-coupled receptor Ste2.

The main sterol of the human cell membrane is cholesterol, whereas in yeast it is ergosterol. In this study, we constructed a cholesterol-producing yeast strain by disrupting the genes related to ergosterol synthesis and inserting the genes related to cholesterol synthesis. The total sterols of the mutant yeast were extracted and the sterol composition was analyzed by GC-MS. We confirmed that cholesterol was produced instead of ergosterol in yeast and subsequently examined the activity of the yeast G-protein-coupled receptor (GPCR) Ste2p. Ste2p signaling was assessed in wild type (WT) with ergosterol and the cholesterol-producing yeast instead of ergosterol to determine whether sterol composition affects the activity of the yeast GPCR. Our results demonstrated that Ste2p could transduce a signal even in the cholesterol-rich membrane, but the maximum signal intensity was weaker than that transduced in the ergosterol-rich original (WT) membrane. This result indicates that sterol composition affects the activity of yeast GPCRs, and thus, this provides new insight into GPCR-mediated transduction using yeast for future fundamental and applied studies on GPCRs from yeast to other organisms.

Current Status of Robotic Gastrointestinal Surgery.

Development of surgical support robots began in the 1980s as a navigation and auxiliary device for endoscopic surgery. For remote surgery on the battlefield, a master-slave-type surgical support robot was developed, in which a console surgeon operates the robot at will. The da Vinci surgical system, which currently dominates the global robotic surgery market, received United States Food and Drug Administration and regulatory approval in Japan in 2000 and 2009 respectively. The latest, fourth generation, da Vinci Xi has a good field of view via a three-dimensional monitor, highly operable forceps, a motion scale function, and a tremor-filtered articulated function. Gastroenterological tract robotic surgery is safe and minimally invasive when accessing and operating on the esophagus, stomach, colon, and rectum. The learning curve is said to be short, and robotic surgery will likely be standardized soon. Therefore, robotic surgery training should be systematized for young surgeons so that it can be further standardized and later adapted to a wider range of surgeries. This article reviews current trends and potential developments in robotic surgery.

Chimeric yeast G-protein α subunit harboring a 37-residue C-terminal gustducin-specific sequence is functional in Saccharomyces cerevisiae.

Despite many recent studies of G-protein-coupled receptor (GPCR) structures, it is not yet well understood how these receptors activate G proteins. The GPCR assay using baker's yeast, Saccharomyces cerevisiae, is an effective experimental model for the characterization of GPCR-Gα interactions. Here, using the yeast endogenous Gα protein (Gpa1p) as template, we constructed various chimeric Gα proteins with a region that is considered to be necessary for interaction with mammalian receptors. The signaling assay using the yeast pheromone receptor revealed that the chimeric Gα protein harboring 37 gustducin-specific amino acid residues at its C-terminus (GPA1/gust37) maintained functionality in yeast. In contrast, GPA1/gust44, a variant routinely used in mammalian experimental systems, was not functional.

Three 4-monosubstituted butyrolactones from a regulatory gene mutant of Streptomyces rochei 7434AN4.

Extensive metabolite analysis of Streptomyces rochei 7434AN4 was performed to discover uncharacterized secondary metabolites. A mutant strain of S. rochei, in which two regulatory genes srrC (a tetR-type repressor) and srrY (SARP-type activator) were inactivated, accumulated three 4-monosubstituted γ-butyrolactones YT02-A, YT02-B, and KH01-A, which were not detected in the parent strain. Their structures were identified as 4,10-dihydroxy-10-methyldodecan-4-olide, 4,10-dihydroxy-10-methylundecan-4-olide, and 4-hydroxy-11-oxo-10-methyldodecan-4-olide. A structural comparison indicated that the three butanolides and the signaling molecules, termed S. rochei butenolides (SRBs), could share common C12 or C13 fatty acids for their biosynthesis intermediates, however, these three butanolides did not induce antibiotic production even at 50 µM concentration (1000-folds of the minimum antibiotic-inducing concentration of SRBs) in S. rochei.