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Biomedical subjects

John Hancock

Publications and source records attributed to John Hancock.

8 recordsLinked to original sources
PubMed2025

Establishing the ELIXIR Microbiome Community.

Microbiome research has grown substantially over the past decade in terms of the range of biomes sampled, identified taxa, and the volume of data derived from the samples. In particular, experimental approaches such as metagenomics, metabarcoding, metatranscriptomics and metaproteomics have provided profound insights into the vast, hitherto unknown, microbial biodiversity. The ELIXIR Marine Metagenomics Community, initiated amongst researchers focusing on marine microbiomes, has concentrated on promoting standards around microbiome-derived sequence analysis, as well as understanding the gaps in methods and reference databases, and identifying solutions to the computational overheads of performing such analyses. Nevertheless, the methods used and the challenges faced are not confined to marine microbiome studies, but are broadly applicable to other biomes. Thus, expanding this Marine Metagenomics Community to a more inclusive ELIXIR Microbiome Community will enable it to encompass a broader range of biomes and link expertise across 'omics technologies. Furthermore, engaging with a large number of researchers will improve the efficiency and sustainability of bioinformatics infrastructure and resources for microbiome research (standards, data, tools, workflows, training), which will enable a deeper understanding of the function and taxonomic composition of the different microbial communities.

Computational Biology↗
PubMed2006

Doing the unexpected: proteins involved in hydrogen peroxide perception.

A look back at the early literature on reactive oxygen species (ROS) gives the impression that these small inorganic molecules had a singular defined role, that of host defence in mammalian systems. However, it is now known that their roles also include a major part in cell signalling, in a broad range of organisms from mammals to plants. Similarly, a look back at papers on the proteins now thought to be involved in the perception of hydrogen peroxide (H(2)O(2)) will show that they too had defined functions assigned to them, completely independent to H(2)O(2) signalling. These proteins have disparate roles, in ethylene perception or even major metabolic pathways such as glycolysis. However, the chemistry of H(2)O(2) sensing dictates that the proteins have a commonality, with active thiol groups being potential ROS targets. The challenge now is to determine the full range of proteins which may partake in the role of H(2)O(2) perception, and to determine the mechanisms by which the signal is transmitted to the next players in the signal transduction pathways.

Glyceraldehyde-3-Phosphate Dehydrogenases↗
PubMed2006

Secondary interventions following endovascular repair of abdominal aortic aneurysm.

PURPOSE: To review the outcomes of endovascular abdominal aortic aneurysm repair (EVAR) procedures, to determine the incidence of adverse events, and to assess the need for secondary radiological/surgical interventions. MATERIALS AND METHODS: Data from 57 consecutive patients entered in a prospective EVAR database were studied. In addition to database interrogation, case notes and radiology records were reviewed. Frequency and outcome of complications were evaluated after stent-graft placement (mean follow up 20 months). RESULTS: Overall, 24 adverse events were recorded in 57 patients (42%). The events were endoleaks (14/24), stent migrations (3/24), deployment problems (2/24), limb occlusions (2/24), limb kink (1/24), and femoro-femoral crossover occlusions (2/24). Of all the endovascular patients studied, 23% (13/57) required secondary interventions to maintain aneurysm exclusion. The mean time to secondary intervention in this series was 14 months. CONCLUSION: Over 40% of EVAR procedures were associated with suboptimal clinical outcomes, and more than 20% of the patients required secondary interventions within 5 years of surgery. This high incidence of late secondary intervention is a cause for concern and emphasizes the need for lifelong follow-up.

Aged↗
PubMed2004

Thrombolysis for central venous occlusion causing bilateral chylothorax in a patient with down syndrome.

A 20-year-old woman with Down syndrome (trisomy 21) and acute lymphoblastic leukemia presented with severe respiratory compromise secondary to bilateral chylothorax as a result of central venous thrombosis and extensive upper-limb deep venous thrombosis. The chylothorax was successfully managed by catheter-directed thrombolysis and angioplasty of the venous occlusions. The development of venous thrombosis was likely to have been multifactorial. It is recognized that there is an increased incidence of congenital lymphatic anomalies in Down syndrome, which may have been a contributing factor in the development of chylothorax in this patient. This report illustrates the angiographic findings, demonstrates the successful vascular recanalization, and discusses the etiology and management of central venous thrombosis and chylothorax. The case is also presented to contribute to the expanding evidence in support of catheter-directed venous thrombolysis in selected clinical circumstances.

Adult↗
PubMed2002

A new role for an old enzyme: nitrate reductase-mediated nitric oxide generation is required for abscisic acid-induced stomatal closure in Arabidopsis thaliana.

The plant hormone abscisic acid (ABA), synthesized in response to water-deficit stress, induces stomatal closure via activation of complex signaling cascades. Recent work has established that nitric oxide (NO) is a key signaling molecule mediating ABA-induced stomatal closure. However, the biosynthetic origin of NO in guard cells has not yet been resolved. Here, we provide pharmacological, physiological, and genetic evidence that NO synthesis in Arabidopsis guard cells is mediated by the enzyme nitrate reductase (NR). Guard cells of wild-type Arabidopsis generate NO in response to treatment with ABA and nitrite, a substrate for NR. Moreover, NR-mediated NO synthesis is required for ABA-induced stomatal closure. However, in the NR double mutant, nia1, nia2 that has diminished NR activity, guard cells do not synthesize NO nor do the stomata close in response to ABA or nitrite, although stomatal opening is still inhibited by ABA. Furthermore, by using the ABA-insensitive (ABI) abi1-1 and abi2-1 mutants, we show that the ABI1 and ABI2 protein phosphatases are downstream of NO in the ABA signal-transduction cascade. These data demonstrate a previously uncharacterized signaling role for NR, that of mediating ABA-induced NO synthesis in Arabidopsis guard cells.

Abscisic Acid↗
PubMed2002

Hydrogen peroxide signalling.

Recent biochemical and genetic studies confirm that hydrogen peroxide is a signalling molecule in plants that mediates responses to abiotic and biotic stresses. Signalling roles for hydrogen peroxide during abscisic-acid-mediated stomatal closure, auxin-regulated root gravitropism and tolerance of oxygen deprivation are now evident. The synthesis and action of hydrogen peroxide appear to be linked to those of nitric oxide. Downstream signalling events that are modulated by hydrogen peroxide include calcium mobilisation, protein phosphorylation and gene expression. Calcium and Rop signalling contribute to the maintenance of hydrogen peroxide homeostasis.

Abscisic Acid↗
PubMedDate not supplied

Comparison of cytology proficiency testing: glass slides vs. virtual slides.

OBJECTIVE: To compare proficiency testing in gynecologic cytology using glass slides vs. virtual slides. STUDY DESIGN: To compare performance, a sample of 111 individuals (pathologists = 52, cytotechnologists = 59) from participating in-state laboratories were administered 2 proficiency tests. The annual test of the Maryland Cytology Proficiency Testing Program (MCPTP) was administered to individuals in their laboratories following normal work practice (i.e., using microscopes and equipment with which they were familiar). The other test was CytoView II (Centers for Disease Control and Prevention, Atlanta, Georgia, U.S.A.), a computer-based test composed of virtual slides captured from the MCPTP's glass slides, which test administration personnel transported to the individual's laboratory and administered using 1 of 2 laptop computers. ANOVA was used to compare the performance on the 2 tests and the effect of various potential confounding variables. The slides were evaluated by comparing the performance average for each glass slide to that of the matching virtual slides. All data analysis was performed at the 95% confidence interval. RESULTS: The mean score of the individuals (n = 111) on the MCPTP test was 99.2% (SD = 2.2, range = 90-100%). The mean score of the individuals (n = 111) on CytoView II was 96.8% (SD = 5.8, range = 70-100%). No individual scored < 90% on the glass slide test (pass rate = 100%). Eight individuals (pathologists = 3, cytotechnologists = 5) scored < 90% on the CytoView II (pass rate = 93.8%). Comparison of an individual's performance on the 2 tests demonstrated a significant difference. When virtual slides that did not attain a 90% consensus were excluded from the scoring, a comparison of individual pass rate for the glass slide test (100%) and computer-based test (99.1%) did not demonstrate significant difference. CONCLUSION: Each slide (glass or virtual) must be field validated by cytotechnologists and pathologists. If field validation and Clinical Laboratory Improvement Amendment referencing of virtual slides are comparable to those of glass slides, computer-based testing can be equivalent.

Cell Biology↗