404 research outputs found
Cardiogenic Shock
80% of people developing shock after
myocardial infarction die. This essay is concerned to ask why they die and what can be done
about it.Accordingly it consists of two parts:
the one concerned with the definition and some
relevant aspects of the pathogenesis of cardiogenic shock; the other concerned with therapy,
its difficulties and its future
Are South African doctoral qualifications educating the thinkers we need?
Significance:
The recently completed national review of the doctoral qualifications offered by South African higher education institutions has provided important insights into the national landscape of doctoral education, and raised many questions. One key question is whether our doctoral qualifications educate our students to be the broad and critical thinkers needed to address current and future scientific and societal challenges. In the South African higher education context, we must ask ourselves whether we are providing the academic and intellectual depth required to enable our doctoral graduates to achieve the graduate attributes that we express as our national aspirations, and we need to consider new approaches to doctoral education
Cyclin-dependent kinase inhibitor drugs drive neutrophil granulocyte apoptosis by transcriptional inhibition of the key survival protein MCL-1
The normal physiological response to bacterial infection or wounding with threat
of infection, termed inflammation, has been shown to be dysregulated in certain
human diseases including (but not limited to): idiopathic pulmonary fibrosis, acute
lung injury, arthritis and glomerulonephritis. The earliest arriving and most
abundant cell responding to an inflammatory stimulus is the neutrophil
granulocyte. It has been shown that under inflammatory conditions neutrophil
granulocytes have extended longevity, enhanced responsiveness and upregulated
activation parameters. In the setting of non-infective, or prolonged, ineffectuallycleared
infective disease where resolution of inflammation does not occur then
neutrophil granulocytes may cause tissue damage which is mediated by excessive,
misdirected exocytosis of toxic granule contents or by spillage of the same
products from necrotic or netotic cell carcasses that have lost membrane integrity.
A key process in the resolution of inflammation is the induction of apoptosis in
recruited neutrophils following a successful response to an inflammatory stimulus.
Cellular signalling from apoptotic cells and from professional phagocytes that have
ingested apoptotic cells has been shown to favour resolution of inflammation and
restoration of tissue homeostasis. Additionally, the removal of key inflammatory
cells in a highly regulated, non-phlogistic fashion robustly assists the resolution
process.
Cyclin-dependent kinase (CDK) inhibitor drugs are being developed as anti-cancer
agents as it is hypothesized that they should interfere with the enhanced cellcycling
ability (increased proliferative capacity and extended longevity) which is
such a key feature of cancer cell biology. The CDKs that drive the cell cycle are
CDKs 1, 2, 4 and 6 and consequently agents were designed to have enhanced
specificity for these targets. CDK inhibitor drugs target the ATP-binding domain
of CDKs and as a result usually have activity against more than one CDK. The
CDK inhibitor drug, R-roscovitine which targets CDKs 2, 5, 7 and 9 was shown to promote neutrophil apoptosis and consequently resolution of inflammation. This
thesis aims to investigate the mechanism by which apoptosis is induced in
neutrophil granulocytes by CDK inhibitor drugs.
The first experimental chapter of this thesis explores in detail the time-course and
active concentration range of CDK inhibitor drugs in comparison to known
promoters and inhibitors of neutrophil apoptosis. It then dissects the apoptotic
machinery which is responsible for the effects of CDK inhibitor drugs before
investigating their capacity to promote apoptosis even in the presence of survival
mediators relevant to the context of inflammatory disease. Flow-cytometry, light
and confocal microscopy as well as western blotting for caspases, mitochondrial
dissipation assay, fluorometric caspase assay and the detection of DNA laddering
demonstrate that CDK inhibitor drugs promote classical neutrophil apoptosis by
the intrinsic pathway and show similar kinetics of apoptosis induction to drugs
that inhibit transcription.
The second experimental chapter investigates the key neutrophil survival protein
and bcl-2 homologue Mcl-1. By flow cytometry, western blotting and RT-PCR it is
demonstrated that Mcl-1 is down-regulated at the level of transcription and that
this occurs even in the presence of inflammatory mediators that would normally
promote neutrophil survival. Additionally, it is shown that pro-apoptotic bcl-2
homologues are affected to a lesser degree suggesting an imbalance of bcl-2
proteins is caused by effects at a transcriptional level mediated by CDK inhibitor
drugs.
The third experimental chapter identifies CDKs and their binding partner cyclins in
neutrophil granulocytes and investigates the impact of CDK inhibitor drugs on
CDK protein levels and cellular distribution by differential lysis and western
blotting as well as by confocal microscopy. The key transcriptional enzyme RNA
polymerase II is also identified and the effect of CDK inhibitor drugs on phosphorylation of this enzyme is documented. Western blotting and confocal
microscopy demonstrate the presence of key CDKs 2, 5, 7, 9 and cyclin binding
partners of CDKs 7 and 9. It is shown that the phosphorylation of RNA
polymerase II mediated by CDKs 7 and 9 is inhibited by CDK inhibitor drugs.
This suggests that a key mechanism by which neutrophil apoptosis is induced by
CDK inhibitor drugs is the inhibition of transcription of key proteins and suggests
that neutrophils require survival proteins for functional longevity.
The fourth experimental chapter addresses the production and use of HIV-tat
dominant negative CDK 7 and 9 proteins to knockdown CDKs 7 and 9 in
neutrophil granulocytes in vitro to provide a molecular biology surrogate for the
pharmacological data already presented. The cloning, production, purification and
use of HIV-tat dominant negative CDK proteins are described.
The final chapter describes the use of a more specific pharmacological inhibitor of
CDKs 7 and 9, DRB, in the mouse bleomycin lung injury model. Resolution of
inflammation by a compound specifically targeting CDKs 7 and 9 is described.
This thesis identifies CDKs 7 and 9 as key targets of CDK inhibitor drugs in
neutrophilic inflammation. It shows these drugs acting at the level of transcription
to drive neutrophil apoptosis by exploiting the unique dependency of neutrophils
on the short-lived survival protein Mcl-1. In so doing the presence of functional
and essential transcriptional machinery is identified in neutrophils and the
transcriptional profile of resting, stimulated and inhibited neutrophils is delineated.
These findings suggest novel approaches to the pharmacological promotion of
resolution of inflammation and indicate key new targets for rational drug design. In
future, it will be important to further characterize the effects of CDK inhibitor
drugs on other cell-types including epithelial cells, fibroblasts and mononuclear
cells. This information should prove important to the continued investigation of CDK inhibitor drugs in resolution of inflammation and also to the ongoing
experimental trial of these drugs in idiopathic pulmonary fibrosis
Cardiogenic Shock
DEFINITION AND PATHOGENESISINCIDENCECardiogenic shock is shock occurring after myocardial infarction. It has been variously described as occurring in 6%, 8%, 10%, 12% and 20% of patients with myocardial infarction. Shock accompanies the onset of pain in few eases and most cases occur in the first twenty-four hours after infarction although they may occur several days after.CLINICAL CRITERIAThe criteria for diagnosis of shock may vary with different authors (hence the anomalous 20% above) but, in general, it is agreed that shock is suggested clinically by the following features: cold, clammy extremities, pallor and cyanosis, rapid, thready pulse, anuria or oliguria, anxiety, restlessness or apathy, and prolonged hypotension. The only objective assessment is of blood pressure and this alone does not define shock. Considerable variation may therefore be expected in diagnosis.In view of the difficulties in defining the criteria for diagnosis of shock, the individual criteria and the interpretations placed upon them warrant further discussion.
Chromosomal diversification and karyotype evolution of diploids in the cytologically diverse genus Prospero (Hyacinthaceae)
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited
Management of patients with lower-risk myelodysplastic syndromes.
Myelodysplastic syndromes (MDS) are a heterogeneous group of hematopoietic stem cell disorders characterized by ineffective hematopoiesis with abnormal blood cell development (dysplasia) leading to cytopenias and an increased risk for progression to acute myeloid leukemia (AML). Patients with MDS can generally be classified as lower- (LR-MDS) or higher-risk (HR-MDS). As treatment goals for patients with LR-MDS and those with HR-MDS differ significantly, appropriate diagnosis, classification, and follow-up are critical for correct disease management. In this review, we focus on the diagnosis, prognosis, and treatment options, as well as the prediction of the disease course and monitoring of treatment response in patients with LR-MDS. We discuss how next-generation sequencing, increasing knowledge on mechanisms of MDS pathogenesis, and novel therapies may change the current treatment landscape in LR-MDS and why structured assessments of responses, toxicities, and patient-reported outcomes should be incorporated into routine clinical practice
Analysis of the giant genomes of Fritillaria (Liliaceae) indicates that a lack of DNA removal characterizes extreme expansions in genome size.
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.Plants exhibit an extraordinary range of genome sizes, varying by > 2000-fold between the smallest and largest recorded values. In the absence of polyploidy, changes in the amount of repetitive DNA (transposable elements and tandem repeats) are primarily responsible for genome size differences between species. However, there is ongoing debate regarding the relative importance of amplification of repetitive DNA versus its deletion in governing genome size. Using data from 454 sequencing, we analysed the most repetitive fraction of some of the largest known genomes for diploid plant species, from members of Fritillaria. We revealed that genomic expansion has not resulted from the recent massive amplification of just a handful of repeat families, as shown in species with smaller genomes. Instead, the bulk of these immense genomes is composed of highly heterogeneous, relatively low-abundance repeat-derived DNA, supporting a scenario where amplified repeats continually accumulate due to infrequent DNA removal. Our results indicate that a lack of deletion and low turnover of repetitive DNA are major contributors to the evolution of extremely large genomes and show that their size cannot simply be accounted for by the activity of a small number of high-abundance repeat families.Thiswork was supported by the Natural Environment ResearchCouncil (grant no. NE/G017 24/1), the Czech Science Fou nda-tion (grant no. P501/12/G090), the AVCR (grant no.RVO:60077344) and a Beatriu de Pinos postdoctoral fellowshipto J.P. (grant no. 2011-A-00292; Catalan Government-E.U. 7thF.P.)
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