Probing the Electron Accepting Orbitals of Ni-Centered Hydrogen Evolution Catalysts with Noninnocent Ligands by Ni L-Edge and S K-Edge X-ray Absorption

Koroidov, Sergey,Hong, Kiryong,Kjaer, Kasper S.,Li, Lin,Kunnus, Kristjan,Reinhard, Marco,Hartsock, Robert W.,Amit, Das,Eisenberg, Richard,Pemmaraju, C. Das,Gaffney, Kelly J.,Cordones, Amy A. American Chemical Society 2018 Inorganic Chemistry Vol.57 No.21

<P>The valence electronic structure of several square planar Ni-centered complexes, previously shown to catalyze the hydrogen evolution reaction, are characterized using S K-edge and Ni L-edge X-ray absorption spectroscopy and electronic structure calculations. Measurement of the atomic Ni 3d and S 3p contributions enables assessment of the metal-ligand covalency of the electron accepting valence orbitals and yields insight into the ligand-dependent reaction mechanisms proposed for the catalysts. The electron accepting orbital of the Ni(abt)<SUB>2</SUB> (abt = 2-aminobenzenethiolate) catalyst is found to have large ligand character (80%), with only 9% S 3p (per S) character, indicating delocalization over the entire abt ligand. Upon two proton-coupled reductions to form the Ni(abt-H)<SUB>2</SUB> intermediate, the catalyst stores 1.8 electrons on the abt ligand, and the ligand N atoms are protonated, thus supporting its role as an electron and proton reservoir. The electron accepting orbitals of the Ni(abt-H)<SUB>2</SUB> intermediate and Ni(mpo)<SUB>2</SUB> (mpo = 2-mercaptopyridyl-<I>N</I>-oxide) catalyst are found to have considerably larger Ni 3d (46-47%) and S 3p (17-18% per S) character, consistent with an orbital localized on the metal-ligand bonds. This finding supports the possibility of metal-based chemistry, resulting in Ni-H bond formation for the reduced Ni(abt-H)<SUB>2</SUB> intermediate and Ni(mpo)<SUB>2</SUB> catalyst, a critical reaction intermediate in H<SUB>2</SUB> generation.</P><P>The electronic structure of Ni-centered hydrogen evolution catalysts with noninnocent ligands was characterized using S and Ni edge X-ray absorption spectroscopies. The electron-accepting valence orbitals involved in catalysis are found to have high (>50%) ligand character. Ligand-dependent differences in electronic structure provide insight into the previously proposed reaction mechanisms of the catalysts.</P> [FIG OMISSION]</BR>

A Systematic Review of Cervical Cancer Incidence and Mortality in the Pacific Region

Obel, J.,Souares, Y.,Hoy, D.,Baravilala, W.,Garland, S.M.,Kjaer, S.K.,Roth, A. Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.21

This study provides the first systematic literature review of cervical cancer incidence and mortality as well as human papillomavirus (HPV) genotype prevalence among women with cervical cancer in the Pacific Island countries and territories. The cervical cancer burden in the Pacific Region is substantial, with age standardized incidence rates ranging from 8.2 to 50.7 and age standardized mortality rate from 2.7 to 23.9 per 100,000 women per year. The HPV genotype distribution suggests that 70-80% of these cancers could be preventable by the currently available bi- or quadrivalent HPV vaccines. There are only few comprehensive studies examining the epidemiology of cervical cancer in this region and no published data have hitherto described the current cervical cancer prevention initiatives in this region.

Mapping HPV Vaccination and Cervical Cancer Screening Practice in the Pacific Region-Strengthening National and Regional Cervical Cancer Prevention

Obel, J,McKenzie, J,Buenconsejo-Lum, LE,Durand, AM,Ekeroma, A,Souares, Y,Hoy, D,Baravilala, W,Garland, SM,Kjaer, SK,Roth, A Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.8

Objective : To provide background information for strengthening cervical cancer prevention in the Pacific by mapping current human papillomavirus (HPV) vaccination and cervical cancer screening practices, as well as intent and barriers to the introduction and maintenance of national HPV vaccination programmes in the region. Materials and Methods: A cross-sectional questionnaire-based survey among ministry of health officials from 21 Pacific Island countries and territories (n=21). Results: Cervical cancer prevention was rated as highly important, but implementation of prevention programs were insufficient, with only two of 21 countries and territories having achieved coverage of cervical cancer screening above 40%. Ten of 21 countries and territories had included HPV vaccination in their immunization schedule, but only two countries reported coverage of HPV vaccination above 60% among the targeted population. Key barriers to the introduction and continuation of HPV vaccination were reported to be: (i) Lack of sustainable financing for HPV vaccine programs; (ii) Lack of visible government endorsement; (iii) Critical public perception of the value and safety of the HPV vaccine; and (iv) Lack of clear guidelines and policies for HPV vaccination. Conclusion: Current practices to prevent cervical cancer in the Pacific Region do not match the high burden of disease from cervical cancer. A regional approach, including reducing vaccine prices by bulk purchase of vaccine, technical support for implementation of prevention programs, operational research and advocacy could strengthen political momentum for cervical cancer prevention and avoid risking the lives of many women in the Pacific.

Expression analyses of human cleft palate tissue suggest a role for osteopontin and immune related factors in palatal development

Linda P. Jakobsen,Rehannah Borup,Janni Vestergaard,Lars A. Larsen,Kasper Lage,Lisa Leth Maroun,Inger Kjaer,Carsten U. Niemann,Mikael Andersen,Mary A. Knudsen,Kjeld Møllgård,Niels Tommerup 생화학분자생물학회 2009 Experimental and molecular medicine Vol.41 No.2

Cleft lip and/or palate (CL/P) is a common congenital malformation with a complex etiology which is not fully elucidated yet. Epidemiological studies point to different etiologies in the cleft lip and palate subgroups, isolated cleft lip (CL), isolated cleft palate (CP) and combined cleft lip and palate (CLP). In order to understand the biological basis in these cleft lip and palate subgroups better we studied the expression profiles in human tissue from patients with CL/P. In each of the CL/P subgroups, samples were obtained from three patients and gene expression analysis was performed. Moreover, selected differentially expressed genes were analyzed by quantitative RT-PCR, and by immunohistochemical staining of craniofacial tissue from human embryos. Osteopontin (SPP1) and other immune related genes were significantly higher expressed in palate tissue from patients with CLP compared to CP and immunostaining in palatal shelves against SPP1, chemokine receptor 4 (CXCR4) and serglycin (PRG1) in human embryonic craniofacial tissue were positive, supporting a role for these genes in palatal development. However, gene expression profiles are subject to variations during growth and therefore we recommend that future gene expression in CL/P studies should use tissue from the correct embryonic time and place if possible, to overcome the biases in the presented study. Cleft lip and/or palate (CL/P) is a common congenital malformation with a complex etiology which is not fully elucidated yet. Epidemiological studies point to different etiologies in the cleft lip and palate subgroups, isolated cleft lip (CL), isolated cleft palate (CP) and combined cleft lip and palate (CLP). In order to understand the biological basis in these cleft lip and palate subgroups better we studied the expression profiles in human tissue from patients with CL/P. In each of the CL/P subgroups, samples were obtained from three patients and gene expression analysis was performed. Moreover, selected differentially expressed genes were analyzed by quantitative RT-PCR, and by immunohistochemical staining of craniofacial tissue from human embryos. Osteopontin (SPP1) and other immune related genes were significantly higher expressed in palate tissue from patients with CLP compared to CP and immunostaining in palatal shelves against SPP1, chemokine receptor 4 (CXCR4) and serglycin (PRG1) in human embryonic craniofacial tissue were positive, supporting a role for these genes in palatal development. However, gene expression profiles are subject to variations during growth and therefore we recommend that future gene expression in CL/P studies should use tissue from the correct embryonic time and place if possible, to overcome the biases in the presented study.