Studies in Organic Geochemistry

Organic geochemistry is the study of organic matter in geological situations, including contemporary environments. One facet of the subject is the isolation and identification of organic compounds from fossils and sediments. Correlations are then sought between such compounds and the biological compounds present in contemporary organisms, bearing in mind the chemical changes which could have taken place. in this thesis an attempt has been made to relate chemically a living alga, Botryococcus braunii , a derived rubbery deposit called Cocrengite and Torbanite which is a sediment 300 million years in age. The thesis can be divided into six parts, five of which are concerned with organic geochemistry. The Introduction reviews the more significant contributions to organic geochemistry and describes the types of compounds found in sediments, with special reference to alkanes. Some of the various facets of the subject and the possible derivations of geological isoprenoid alkanes ere also discussed. Section I is concerned with the alkanes present in two samples of a young sediment (ca. 30 x 10e6 yrs.) from N. W. Bohemia, Czechoslovakia. The distributions of the normal alkanes are reminiscent of those of the normal alkanes of the surface waxes of most contemporary plants. Furthermore the predominance of triterpene hydrocarbons in the branched-cyclic aIkam fraction is in accordance with the fact that the plant species identified in the sediment are mainly angiosperms. The diterpene hydrocarbon fichtelite was identified in one of the samples. Section II deals with the alkanes of a number of samples from the Scottish Carboniferous Formation (ca. 300 x 10e6 yrs.). The normal alkanes of these samples have smooth distributions in contrast to those found for the young sediment examined (Section I). A number of acyclic isoprenoid hydrocarbons were identified, indicating that the samples have a biological origin. Triterpene hydrocarbons were isolated from one of the samples, viz. the Westwood Shale and their occurrence reflects the difference in source material between this and a closely related sediment called Torbanite. The Westwood Shale is the oldest geological sample from which triterpanes have been isolated in a pure state. Section III describes the hydrocarbons of a rubbery deposit called Coorongite (ca. 40 yrs.) which is the presumed precursor of Torbanite. The unusual hydrocarbon distributions found in Coorongite are thought by the author to be the result of bacterial activity. Three acyclic isopronoid hydrocarbons were identified in the sample examined. Section IV deals with the hydrocarbons of a living alga, Botryococcus braunii, which gives rise to Coorongite. No saturated hydrocarbons were detected in the alga and the hydrocarbon fraction was found to consist almost entirely of two novel hydrocarbons. Approaches to the structural elucidation of these hydrocarbons are described. The Appendix is concerned with the interactions which can take place between a nitro-group and a side chain in orthosubstituted nitrobenzenes . The types of interaction which have been observed are reviewed and two new examples are descried. A mass spectral method for the identification of the N-oxide function in aromatic N-oxides is discussed

ASSESSMENT OF ESSAYS IN A MANAGEMENT SCIENCE COURSE

The ability to communicate a problem statement and an appropriate quantitative business method are important professional skills. This paper presents an analysis of student skill in writing a final exam essay that describes how a specific organization can improve decision making using mathematical programming, the business modeling approach that was the focus of the course. Although performance on assessments of professional writing and the description of a mathematical programming model averaged less than 80% across all essays written, improved writing when students received formative feedback in 2013 suggests that teaching students to identify and articulate the development and use of business tools through written communication is an important area for future business research

A Role for von Hippel-Lindau Protein in Pancreatic β-Cell Function

OBJECTIVE—The Vhlh gene codes for the von Hippel-Lindau protein (VHL), a tumor suppressor that is a key player in the cellular response to oxygen sensing. In humans, a germline mutation in the VHL gene leads to the von Hippel-Lindau disease, a familial syndrome characterized by benign and malignant tumors of the kidney, central nervous system, and pancreas

IGF binding protein‐6 expression in vascular endothelial cells is induced by hypoxia and plays a negative role in tumor angiogenesis

Hypoxia stimulates tumor angiogenesis by inducing the expression of angiogenic molecules. The negative regulators of this process, however, are not well understood. Here, we report that hypoxia induced the expression of insulin‐like growth factor binding protein‐6 (IGFBP‐6), a tumor repressor, in human and rodent vascular endothelial cells (VECs) via a hypoxia‐inducible factor (HIF)‐mediated mechanism. Addition of human IGFBP‐6 to cultured human VECs inhibited angiogenesis in vitro . An IGFBP‐6 mutant with at least 10,000‐fold lower binding affinity for IGFs was an equally potent inhibitor of angiogenesis, suggesting that this action of IGFBP‐6 is IGF‐independent. The functional relationship between IGFBP‐6 and vascular endothelial growth factor (VEGF), a major hypoxia‐inducible angiogenic molecule, was examined. While VEGF alone increased angiogenesis in vitro , co‐incubation with IGFBP‐6 abolished VEGF‐stimulated angiogenesis. The in vivo role of IGFBP‐6 in angiogenesis was tested in flk1 :GFP zebrafish embryos, which exhibit green fluorescence protein in developing vascular endothelium, permitting visualization of developing blood vessels. Injection of human IGFBP‐6 mRNA reduced the number of embryonic inter‐segmental blood vessels by ∼40%. This anti‐angiogenic activity is conserved in zebrafish because expression of zebrafish IGFBP‐6b had similar effects. To determine the anti‐angiogenic effect of IGFBP‐6 in a tumor model, human Rh30 rhabdomyosarcoma cells stably transfected with IGFBP‐6 were inoculated into athymic BALB/c nude mice. Vessel density was 52% lower in IGFBP‐6‐transfected xenografts than in vector control xenografts. These results suggest that the expression of IGFBP‐6 in VECs is up‐regulated by hypoxia and IGFBP‐6 inhibits angiogenesis in vitro and in vivo .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90159/1/26201_ftp.pd

The human side of hypoxia-inducible factor

When humans are exposed to hypoxia, systemic and intracellular changes operate together to minimise hypoxic injury and restore adequate oxygenation. Emerging evidence indicates that the hypoxia-inducible factor (HIF) family of transcription factors plays a central regulatory role in these homeostatic changes at both the systemic and cellular levels. HIF was discovered through its action as the transcriptional activator of erythropoietin, and has subsequently been found to control intracellular hypoxic responses throughout the body. HIF is primarily regulated by specific prolyl hydroxylase-domain enzymes (PHDs) that initiate its degradation via the von Hippel-Lindau tumour suppressor protein (VHL). The oxygen and iron dependency of PHD activity accounts for regulation of the pathway by both cellular oxygen and iron status. Recent studies conducted in patients with rare genetic diseases have begun to uncover the wider importance of the PHD-VHL-HIF axis in systems-level human biology. These studies indicate that, in addition to regulating erythropoiesis, the system plays an important role in cardiopulmonary regulation. This article reviews our current understanding of the importance of HIF in human systems-level physiology, and is modelled around the classic physiological response to high-altitude hypoxia

The impact of pre‐operative intravenous iron on quality of life after colorectal cancer surgery: outcomes from the intravenous iron in colorectal cancer‐associated anaemia (IVICA) trial

Anaemia is associated with a reduction in quality of life, and is common in patients with colorectal cancer . Werecently reported thefindings of the intravenous iron in colorectal cancer-associated anaemia (IVICA) trialcomparing haemoglobin levels and transfusion requirements following intravenous or oral iron replacement inanaemic colorectal cancer patients undergoing elective surgery. In this follow-up study, we compared theefficacy of intravenous and oral iron at improving quality of life in this patient group. We conducted amulticentre, open-label randomised controlled trial. Anaemic colorectal cancer patients were randomlyallocated at least two weeks pre-operatively, to receive either oral (ferrous sulphate) or intravenous (ferriccarboxymaltose) iron. We assessed haemoglobin and quality of life scores at recruitment, immediately beforesurgery and at outpatient review approximately three months postoperatively, using the Short Form 36,EuroQoL 5-dimension 5-level and Functional Assessment of Cancer Therapy–Anaemia questionnaires. Werecruited 116 anaemic patients across seven UK centres (oral iron n=61 (53%), and intravenous iron n=55(47%)). Eleven quality of life components increased by a clinically significant margin in the intravenous irongroup between recruitment and surgery compared with one component for oral iron. Median (IQR [range])visual analogue scores were significantly higher with intravenous iron at a three month outpatient review (oraliron 70, (60–85 [20–95]); intravenous iron 90 (80–90 [50–100]), p=0.001). The Functional Assessment ofCancer Therapy–Anaemia score comprises of subscales related to cancer, fatigue and non-fatigue itemsrelevant to anaemia. Median outpatient scores were higher, and hence favourable, for intravenous iron on theFunctional Assessment of Cancer Therapy–Anaemia subscale (oral iron 66 (55–72 [23–80]); intravenous iron 71(66–77 [46–80]); p=0.002), Functional Assessment of Cancer Therapy–Anaemia trial outcome index (oral iron108 (90–123 [35–135]); intravenous iron 121 (113–124 [81–135]); p=0.003) and Functional Assessment ofCancer Therapy–Anaemia total score (oral iron 151 (132–170 [69–183]); intravenous iron 168 (160–174 [125–186]); p=0.005). Thesefindings indicate that intravenous iron is more efficacious at improving quality of lifescores than oral iron in anaemic colorectal cancer patients

Renal tubular HIF-2α expression requires VHL inactivation and causes fibrosis and cysts.

The Hypoxia-inducible transcription Factor (HIF) represents an important adaptive mechanism under hypoxia, whereas sustained activation may also have deleterious effects. HIF activity is determined by the oxygen regulated α-subunits HIF-1α or HIF-2α. Both are regulated by oxygen dependent degradation, which is controlled by the tumor suppressor "von Hippel-Lindau" (VHL), the gatekeeper of renal tubular growth control. HIF appears to play a particular role for the kidney, where renal EPO production, organ preservation from ischemia-reperfusion injury and renal tumorigenesis are prominent examples. Whereas HIF-1α is inducible in physiological renal mouse, rat and human tubular epithelia, HIF-2α is never detected in these cells, in any species. In contrast, distinct early lesions of biallelic VHL inactivation in kidneys of the hereditary VHL syndrome show strong HIF-2α expression. Furthermore, knockout of VHL in the mouse tubular apparatus enables HIF-2α expression. Continuous transgenic expression of HIF-2α by the Ksp-Cadherin promotor leads to renal fibrosis and insufficiency, next to multiple renal cysts. In conclusion, VHL appears to specifically repress HIF-2α in renal epithelia. Unphysiological expression of HIF-2α in tubular epithelia has deleterious effects. Our data are compatible with dedifferentiation of renal epithelial cells by sustained HIF-2α expression. However, HIF-2α overexpression alone is insufficient to induce tumors. Thus, our data bear implications for renal tumorigenesis, epithelial differentiation and renal repair mechanisms

Drosophila Genome-Wide RNAi Screen Identifies Multiple Regulators of HIF–Dependent Transcription in Hypoxia

Hypoxia-inducible factors (HIFs) are a family of evolutionary conserved alpha-beta heterodimeric transcription factors that induce a wide range of genes in response to low oxygen tension. Molecular mechanisms that mediate oxygen-dependent HIF regulation operate at the level of the alpha subunit, controlling protein stability, subcellular localization, and transcriptional coactivator recruitment. We have conducted an unbiased genome-wide RNA interference (RNAi) screen in Drosophila cells aimed to the identification of genes required for HIF activity. After 3 rounds of selection, 30 genes emerged as critical HIF regulators in hypoxia, most of which had not been previously associated with HIF biology. The list of genes includes components of chromatin remodeling complexes, transcription elongation factors, and translational regulators. One remarkable hit was the argonaute 1 (ago1) gene, a central element of the microRNA (miRNA) translational silencing machinery. Further studies confirmed the physiological role of the miRNA machinery in HIF–dependent transcription. This study reveals the occurrence of novel mechanisms of HIF regulation, which might contribute to developing novel strategies for therapeutic intervention of HIF–related pathologies, including heart attack, cancer, and stroke