Dioxygen Activation and Mandelate Decarboxylation by Iron(II) Complexes of N4 Ligands: Evidence for Dioxygen-Derived Intermediates from Cobalt Analogues.

The isolation, characterization, and dioxygen reactivity of monomeric [(TPA)MII(mandelate)]+ (M = Fe, 1; Co, 3) and dimeric [(BPMEN)2MII2(µ-mandelate)2]2+ (M = Fe, 2; Co, 4) (TPA = tris(2-pyridylmethyl)amine and BPMEN = N1,N2-dimethyl-N1,N2-bis(pyridin-2-yl-methyl)ethane-1,2-diamine) complexes are reported. The iron(II)- and cobalt(II)-mandelate complexes react with dioxygen to afford benzaldehyde and benzoic acid in a 1:1 ratio. In the reactions, one oxygen atom from dioxygen is incorporated into benzoic acid, but benzaldehyde does not derive any oxygen atom from dioxygen. While no O2-derived intermediate is observed with the iron(II)-mandelate complexes, the analogous cobalt(II) complexes react with dioxygen at a low temperature (-80 °C) to generate the corresponding cobalt(III)-superoxo species (S), a key intermediate implicated in the initiation of mandelate decarboxylation. At -20 °C, the cobalt(II)-mandelate complexes bind dioxygen reversibly leading to the formation of µ-1,2-peroxo-dicobalt(III)-mandelate species (P). The geometric and electronic structures of the O2-derived intermediates (S and P) have been established by computational studies. The intermediates S and P upon treatment with a protic acid undergo decarboxylation to afford benzaldehyde (50%) with a concomitant formation of the corresponding µ-1,2-peroxo-µ-mandelate-dicobalt(III) (P1) species. The crystal structure of a peroxide species isolated from the cobalt(II)-carboxylate complex [(TPA)CoII(MPA)]+ (5) (MPA = 2-methoxyphenylacetate) supports the composition of P1. The observations of the dioxygen-derived intermediates from cobalt complexes and their electronic structure analyses not only provide information about the nature of active species involved in the decarboxylation of mandelate but also shed light on the mechanistic pathway of two-electron versus four-electron reduction of dioxygen.

A staged approach with initial tumor thrombectomy followed by hepatectomy for icteric-type hepatocellular carcinoma: A case report.

INTRODUCTION: Biliary drainage for patients with icteric-type hepatocellular carcinoma (HCC) is sometimes difficult, because the drainage tube makes contact with the tumor thrombus (TT) and effective drainage cannot be achieved due to hemobilia. PRESENTATION OF CASE: We performed endoscopic naso-biliary drainage for an icteric-type HCC patient; however, the serum bilirubin level was not decreased due to bleeding from the TT. Therefore, we performed tumor thrombectomy in the bile duct and transection of the right hepatic bile duct prior to right hepatectomy. After the first operation, the bilirubin level was decreased, and liver function was recovered so that the patient could undergo right hepatectomy 4 months after the first operation. The postoperative course was uneventful after the second operation and the patient was discharged from the hospital on the 30th postoperative day. The patient is well without recurrence 10 years after surgery. CONCLUSION: Biliary drainage is one of the key points for successful treatment of icteric-type HCC patients. A staged approach with initial tumor thrombectomy followed by hepatectomy should be considered as one of the options for icteric-type HCC.

Feasibility study of postoperative adjuvant chemotherapy with S-1 in patients with biliary tract cancer.

BACKGROUND: The role of adjuvant chemotherapy has not yet been established for patients with resected biliary tract cancer. S-1 has been shown to exert activity against advanced biliary tract cancer. Therefore, we evaluated the feasibility of adjuvant chemotherapy with S-1 in patients with resected biliary tract cancer. METHODS: Patients with complete macroscopic resection of intrahepatic/extrahepatic bile duct, gall bladder, or ampullary cancer were eligible. S-1 was administered orally twice daily for 4 weeks every 6 weeks, up to 4 cycles. The treatment was continued up to 24 weeks or until recurrence/appearance of unacceptable toxicity. The primary endpoint was the treatment completion rate, which was defined as the percentage of patients who received a relative dose intensity of ≥ 75%. This trial was registered as UMIN000004051. RESULTS: Thirty-three patients were enrolled between June 2010 and March 2011. The relative dose intensity was ≥ 75% in 27 patients representing a treatment completion rate of 81.8%. The most common grade 3/4 adverse event was neutropenia (18%). Grade 2 nausea or diarrhea was observed in 12%. The 3-year relapse-free survival rate was 39.4%. The 3-year survival rate was 54.5%. CONCLUSION: Adjuvant chemotherapy with S-1 is feasible treatment in patients with resected biliary tract cancer. It is necessary to conduct a phase III study to confirm the efficacy of adjuvant therapy of S-1 in patients with resected BTC.

Achieving One-Electron Oxidation of a Mononuclear Nonheme Iron(V)-Imido Complex.

A mononuclear nonheme iron(V)-imido complex bearing a tetraamido macrocyclic ligand (TAML), [FeV(NTs)(TAML)]- (1), was oxidized by one-electron oxidants, affording formation of an iron(V)-imido TAML cation radical species, [FeV(NTs)(TAML+•)] (2); 2 is a diamagnetic (S = 0) complex, resulting from the antiferromagnetic coupling of the low-spin iron(V) ion (S = 1/2) with the one-electron oxidized ligand (TAML+•). 2 is a competent oxidant in C-H bond functionalization and nitrene transfer reaction, showing that the reactivity of 2 is greater than that of 1.

A Mononuclear Nonheme Iron(V)-Imido Complex.

Mononuclear nonheme iron(V)-oxo complexes have been reported previously. Herein, we report the first example of a mononuclear nonheme iron(V)-imido complex bearing a tetraamido macrocyclic ligand (TAML), [(TAML)FeV(NTs)]- (1). The spectroscopic characterization of 1 revealed an S = 1/2 Fe(V) oxidation state, an Fe-N bond length of 1.65(4) Å, and an Fe-N vibration at 817 cm-1. The reactivity of 1 was demonstrated in C-H bond functionalization and nitrene transfer reactions.

The secondary coordination sphere and axial ligand effects on oxygen reduction reaction by iron porphyrins: a DFT computational study.

Oxygen reduction reaction (ORR) catalyzed by a bio-inspired iron porphyrin bearing a hanging carboxylic acid group over the porphyrin ring, and a tethered axial imidazole ligand was studied by DFT calculations. BP86 free energy calculations of the redox potentials and pK a's of reaction components involved in the proton coupled electron transfer (PCET) reactions of the ferric-hydroxo and -superoxo complexes were performed based on Born-Haber thermodynamic cycle in conjunction with a continuum solvation model. The comparison was made with iron porphyrins that lack either in the hanging acid group or axial ligand, suggesting that H-bond interaction between the carboxylic acid and iron-bound hydroxo, aquo, superoxo, and peroxo ligands (de)stabilizes the Fe-O bonding, resulting in the increase in the reduction potential of the ferric complexes. The axial ligand interaction with the imidazole raises the affinity of the iron-bound superoxo and peroxo ligands for proton. In addition, a low-spin end-on ferric-hydroperoxo intermediate, a key precursor for O-O cleavage, can be stabilized in the presence of axial ligation. Thus, selective and efficient ORR of iron porphyrin can be achieved with the aid of the secondary coordination sphere and axial ligand interactions.

A High-Valent Iron(IV) Peroxo Core Derived from O2.

Dioxygen-tolerant [NiFe] hydrogenases catalyze not only the conversion of H2 into 2 H(+) and 2 e(-) but also the reduction of O2 to H2O. Chemists have sought to mimic such bifunctional catalysts with structurally simpler compounds to facilitate analysis and improvement. Herein, we report a new [NiFe]-based catalyst for O2 reduction via an O2 adduct. Structural investigations reveal the first example of a side-on iron(IV) peroxo complex.

Characterization of Mononuclear Non-heme Iron(III)-Superoxo Complex with a Five-Azole Ligand Set.

Reaction of O2 with a high-spin mononuclear iron(II) complex supported by a five-azole donor set yields the corresponding mononuclear non-heme iron(III)-superoxo species, which was characterized by UV/Vis spectroscopy and resonance Raman spectroscopy. (1)H NMR analysis reveals diamagnetic nature of the superoxo complex arising from antiferromagnetic coupling between the spins on the low-spin iron(III) and superoxide. This superoxo species reacts with H-atom donating reagents to give a low-spin iron(III)-hydroperoxo species showing characteristic UV/Vis, resonance Raman, and EPR spectra.

Phase I clinical trial of multiple-peptide vaccination for patients with advanced biliary tract cancer.

BACKGROUND: The prognosis of patients with advanced biliary tract cancer (BTC) is extremely poor and only a few standard treatments are available for this condition. We performed a phase I trial to investigate the safety, immune response and anti-tumor effect of vaccination with three peptides derived from cancer-testis antigens. METHODS: This study was conducted as a phase I trial. Nine patients with advanced BTC who had unresectable tumors and were refractory to standard chemotherapy were enrolled. Three HLA-A*2402 restricted epitope peptides-cell division cycle associated 1 (CDCA1), cadherin 3 (CDH3) and kinesin family member 20A (KIF20A)-were administered subcutaneously, and the adverse events and immune response were assessed. The clinical effects observed were the tumor response, progression-free survival (PFS) and overall survival (OS). RESULTS: The three-peptide vaccination was well-tolerated up to a dose of 3 mg per peptide (9 mg total). No grade 3 or 4 adverse events were observed after vaccination. Peptide-specific T cell immune responses were observed in all patients and stable disease was observed in 5 of 9 patients. The median PFS and OS were 3.4 and 9.7 months. The Grade 2 injection site reaction and continuous vaccination after PD judgment appeared to be prognostic of OS. CONCLUSIONS: Multiple-peptide vaccination was well tolerated and induced peptide-specific T-cell responses. TRIAL REGISTRATION: This study was registered with the University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR000003229).

Long-term Vaccination with Multiple Peptides Derived from Cancer-Testis Antigens Can Maintain a Specific T-cell Response and Achieve Disease Stability in Advanced Biliary Tract Cancer.

PURPOSE: The prognosis of patients with advanced biliary tract cancer (BTC) is extremely poor and there are only a few standard treatments. We conducted a phase I trial to investigate the safety, immune response, and antitumor effect of vaccination with four peptides derived from cancer-testis antigens, with a focus on their fluctuations during long-term vaccination until the disease had progressed. EXPERIMENTAL DESIGN: Nine patients with advanced BTC who had unresectable tumors and were refractory to standard chemotherapy were enrolled. HLA-A*2402-restricted epitope peptides, lymphocyte antigen 6 complex locus K, TTK protein kinase, insulin-like growth factor-II mRNA-binding protein 3, and DEP domain containing 1 were vaccinated subcutaneously once a week at doses of 0.5, 1, or 2 mg and continued until disease progression. The adverse events were assessed by Common Terminology Criteria for Adverse Events and the immune response was monitored by an enzyme-linked immunospot assay or by flow cytometry. The clinical effects observed were tumor response, progression-free survival (PFS), and overall survival (OS). RESULTS: Four-peptide vaccination was well tolerated. No grade 3 or 4 adverse events were observed. Peptide-specific T-cell immune responses were observed in seven of nine patients and clinical responses were observed in six of nine patients. The median PFS and OS were 156 and 380 days. The injection site reaction and CTL induction seemed to be prognostic factors of both PFS and OS. CONCLUSIONS: Four-peptide vaccination was well tolerated and seemed to provide some clinical benefit to some patients. These immunologic and clinical responses were maintained over the long term through continuous vaccinations.

Axial ligand effects on vibrational dynamics of iron in heme carbonyl studied by nuclear resonance vibrational spectroscopy.

Nuclear resonance vibrational spectroscopy (NRVS) and density functional theory calculation (DFT) have been applied to illuminate the effect of axial ligation on the vibrational dynamics of iron in heme carbonyl. The analyses of the NRVS data of five- (5c) and six-coordinate (6c) heme-CO complexes indicate that the prominent feature of (57)Fe partial vibrational density of state ((57)FePVDOS) at the 250-300 cm(-1) region is significantly affected by the association of the axial ligand. The DFT calculations predict that the prominent (57)FePVDOS is composed of iron in-plane motions which are coupled with porphyrin pyrrole in-plane (ν(49), ν(50), and ν(53)), an out-of-plane (γ(8)) (two of four pyrrole rings include the in-plane modes, while the rest of pyrrole rings vibrate along the out-of-plane coordinate), and out-of-phase carbonyl C and O atom displacement perpendicular to the Fe-C-O axis. Thus, in the case of the 5c CO-heme the prominent (57)FePVDOS shows sharp and intense feature because of the degeneracy of the e symmetry mode within the framework of C(4v) symmetry molecule, whereas the association of the axial imidazole ligand in the 6c complex with the lowered symmetry results in split of the degenerate vibrational energy as indicated by broader and lower intensity features of the corresponding NRVS peak compared to the 5c structure. The vibrational energy of the iron in-plane motion in the 6c complex is higher than that in 5c, implying that the iron in the 6c complex includes stronger in-plane interaction with the porphyrin compared to 5c. The iron in-plane mode above 500 cm(-1), which is predominantly coupled with the out-of-phase carbonyl C and O atom motion perpendicular to Fe-C-O, called as Fe-C-O bending mode (δ(Fe-C-O)), also suggests that the 6c structure involves a larger force constant for the e symmetry mode than 5c. The DFT calculations along with the NRVS data suggest that the stiffened iron in-plane motion in the 6c complex can be ascribed to diminished pseudo-Jahn-Teller instability along the e symmetry displacement due to an increased a(1)-e orbital energy gap caused by σ* interaction between the iron d(z(2)) orbital and the nitrogen p orbital from the axial imidazole ligand. Thus, the present study implicates a fundamental molecular mechanism of axial ligation of heme in association with a diatomic gas molecule, which is a key primary step toward versatile biological functions.

Cytochrome c(552) from Thermus thermophilus engineered for facile substitution of prosthetic group.

The facile replacement of heme c in cytochromes c with non-natural prosthetic groups has been difficult to achieve due to two thioether linkages between cysteine residues and the heme. Fee et al. demonstrated that cytochrome c(552) from Thermus thermophilus, overproduced in the cytosol of E. coli, has a covalent linkage cleavable by heat between the heme and Cys11, as well as possessing the thioether linkage with Cys14 [Fee, J. A. (2004) Biochemistry 43, 12162-12176]. Prompted by this result, we prepared a C14A mutant, anticipating that the heme species in the mutant was bound to the polypeptide solely through the thermally cleavable linkage; therefore, the removal of the heme would be feasible after heating the protein. Contrary to this expectation, C14A immediately after purification (as-purified C14A) possessed no covalent linkage. An attempt to extract the heme using a conventional acid-butanone method was unsuccessful due to rapid linkage formation between the heme and polypeptide. Spectroscopic analyses suggested that the as-purified C14A possessed a heme b derivative where one of two peripheral vinyl groups had been replaced with a group containing a reactive carbonyl. A reaction of the as-purified C14A with [BH(3)CN](-) blocked the linkage formation on the carbonyl group, allowing a quantitative yield of heme-free apo-C14A. Reconstitution of apo-C14A was achieved with ferric and ferrous heme b and zinc protoporphyrin. All reconstituted C14As showed spontaneous covalent linkage formation. We propose that C14A is a potential source for the facile production of an artificial cytochrome c, containing a non-natural prosthetic group.

Intraosseous glomus tumor of the ulna: a case report with radiographic findings and a review of the literature.

Intraosseous glomus tumors of bone are extremely rare. We report a case of an intraosseous glomus tumor of the ulna. The patient was a 25-year-old woman who had a three-month history of a palpable mass in her right forearm with spontaneous pain. Radiographs showed cortical hypertrophy and a shell-like bone formation surrounding the small osteolytic lesion within the cortex of the ulna diaphysis. The differential diagnosis included benign bone-forming tumors, such as osteoid osteoma. The patient was treated with an en-bloc resection and filling with beta-TCP. Up to one year after the operation there has been no evidence of recurrence.

Preoperative biliary drainage for biliary tract and ampullary carcinomas.

We posed six clinical questions (CQ) on preoperative biliary drainage and organized all pertinent evidence regarding these questions. CQ 1. Is preoperative biliary drainage necessary for patients with jaundice? The indications for preoperative drainage for jaundiced patients are changing greatly. Many reports state that, excluding conditions such as cholangitis and liver dysfunction, biliary drainage is not necessary before pancreatoduodenectomy or less invasive surgery. However, the morbidity and mortality of extended hepatectomy for biliary cancer is still high, and the most common cause of death is hepatic failure; therefore, preoperative biliary drainage is desirable in patients who are to undergo extended hepatectomy. CQ 2. What procedures are appropriate for preoperative biliary drainage? There are three methods of biliary drainage: percutaneous transhepatic biliary drainage (PTBD), endoscopic nasobiliary drainage (ENBD) or endoscopic retrograde biliary drainage (ERBD), and surgical drainage. ERBD is an internal drainage method, and PTBD and ENBD are external methods. However, there are no reports of comparisons of preoperative biliary drainage methods using randomized controlled trials (RCTs). Thus, at this point, a method should be used that can be safely performed with the equipment and techniques available at each facility. CQ 3. Which is better, unilateral or bilateral biliary drainage, in malignant hilar obstruction? Unilateral biliary drainage of the future remnant hepatic lobe is usually enough even when intrahepatic bile ducts are separated into multiple units due to hilar malignancy. Bilateral biliary drainage should be considered in the following cases: those in which the operative procedure is difficult to determine before biliary drainage; those in which cholangitis has developed after unilateral drainage; and those in which the decrease in serum bilirubin after unilateral drainage is very slow. CQ 4. What is the best treatment for post-drainage fever? The most likely cause of high fever in patients with biliary drainage is cholangitis due to problems with the existing drainage catheter or segmental cholangitis if an undrained segment is left. In the latter case, urgent drainage is required. CQ 5. Is bile culture necessary in patients with biliary drainage who are to undergo surgery? Monitoring of bile cultures is necessary for patients with biliary drainage to determine the appropriate use of antibiotics during the perioperative period. CQ 6. Is bile replacement useful for patients with external biliary drainage? Maintenance of the enterohepatic bile circulation is vitally important. Thus, preoperative bile replacement in patients with external biliary drainage is very likely to be effective when highly invasive surgery (e.g., extended hepatectomy for hilar cholangiocarcinoma) is planned.

Resonance Raman enhancement of FeIV=O stretch in high-valent iron porphyrins: an insight from TD-DFT calculations.

Density functional theory (DFT) has been applied to explain the origin of resonance Raman enhancement associated with the Fe(IV)=O stretch observed in iron(IV)oxo porphyrins. To accomplish this electronic excitations of the Im-(Por)Fe(IV)=O model were computed in the 1.5-4.0 eV spectral range using time-dependent DFT (TD-DFT). All electronic transitions having dominant pi-->pi* character were analyzed and assigned in terms of one-electron excitations. It was found that the most intense Soret band has a multi-component character, but the pi (a(2u))-->pi*(d(xz),d(yz)) and pi (a(1u))-->pi*(d(xz),d(yz)) electronic excitations are primarily responsible for observed resonance enhancement of the Fe(IV)=O stretch.

Resonance raman investigation of the specific sensing mechanism of a target molecule by gas sensory proteins.

Specific sensing of gas molecules such as CO, NO, and O2 is a unique function of gas sensory hemoproteins, while hemoproteins carry out a wide variety of functions such as oxygen storage/transport, electron transfer, and catalysis as enzymes. It is important in gas sensory proteins that the heme domain not only recognizes its target molecule but also discriminates against other gases having similar molecular structures. Coordination of a target molecule to the heme is assumed to alter the protein conformation in the vicinity of heme, and the conformation change is propagated to the effector domain where substrate turnover, DNA binding, or interaction with a signal transduction protein is performed differently than the binding of other gases. To understand the appearance of such a specificity, we focus our attention on the ligand-protein interactions in the distal side of heme. In practice, the metal-ligand vibrations as well as internal modes of ligand and heme are measured with resonance Raman spectroscopy for wild-type and some mutant proteins with full-length or limited sensory regions. On the basis of such observations together with the knowledge currently available, we discuss the mechanism of specific sensing of a diatomic molecule in gas sensory proteins.