14 research outputs found
Clinical Management and Evolving Novel Therapeutic Strategies for Patients with Brain Tumors
A dramatic increase in knowledge regarding the molecular biology of brain tumors has been established over the past few years, and this has lead to the development of novel therapeutic strategies for these patients. In this book a review of the options available for the clinical management of patients with these tumors are outlined. In addition advances in radiology both for pre-operative diagnostic purposes along with surgical planning are described. Furthermore a review of newer developments in chemotherapy along with the evolving field of photodynamic therapy both for intra-operative management and subsequent therapy is provided. A discussion of certain surgical management issues along with tumor induced epilepsy is included. Finally a discussion of the management of certain unique problems including brain metastases, brainstem glioma, central nervous system lymphoma along with issues involving patients with a brain tumor and pregnancy is provided
Liver Biopsy
Liver biopsy is recommended as the gold standard method to determine diagnosis, fibrosis staging, prognosis and therapeutic indications in patients with chronic liver disease. However, liver biopsy is an invasive procedure with a risk of complications which can be serious. This book provides the management of the complications in liver biopsy. Additionally, this book provides also the references for the new technology of liver biopsy including the non-invasive elastography, imaging methods and blood panels which could be the alternatives to liver biopsy. The non-invasive methods, especially the elastography, which is the new procedure in hot topics, which were frequently reported in these years. In this book, the professionals of elastography show the mechanism, availability and how to use this technology in a clinical field of elastography. The comprehension of elastography could be a great help for better dealing and for understanding of liver biopsy
Proteomics
Biomedical research has entered a new era of characterizing a disease or a protein on a global scale. In the post-genomic era, Proteomics now plays an increasingly important role in dissecting molecular functions of proteins and discovering biomarkers in human diseases. Mass spectrometry, two-dimensional gel electrophoresis, and high-density antibody and protein arrays are some of the most commonly used methods in the Proteomics field. This book covers four important and diverse areas of current proteomic research: Proteomic Discovery of Disease Biomarkers, Proteomic Analysis of Protein Functions, Proteomic Approaches to Dissecting Disease Processes, and Organelles and Secretome Proteomics. We believe that clinicians, students and laboratory researchers who are interested in Proteomics and its applications in the biomedical field will find this book useful and enlightening. The use of proteomic methods in studying proteins in various human diseases has become an essential part of biomedical research
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Investigating the effects of tau mutations in induced pluripotent stem cell-derived neurons
Microtubule-associated protein tau (MAPT) is a neuronal protein which promotes microtubule
assembly and stabilisation. The MAPT gene is alternatively spliced to give six tau
isoforms: three with 3 microtubule-binding repeats (3R, excluding exon 10) and three with 4
microtubule-binding repeats (4R, including exon 10). MAPT mutations cause the progressive,
degenerative disorder fronto-temporal dementia with Parkinsonism linked to chromosome 17
(FTDP-17T), in which tau becomes abnormally phosphorylated and aggregates. FTDP-17T
related MAPT mutations can either alter exon 10 splicing and the 3R:4R tau isoform ratio
(such as N279K), or affect tau’s biochemical properties (such as P301L and V337M).
In this project, I differentiated induced pluripotent stem cells (iPSCs) derived from control
subjects and people with the N279K or V337M MAPT mutations to monolayer neurons.
There was an increase in the proportion of neurons containing tau phosphorylated at the
AT8 epitope in N279K cultures after 50 days, and more 4R tau was detected earlier in
the N279K cultures than in controls, confirming the action of the N279K mutation. All
monolayer neural cultures matured at similar rates in terms of synapse formation, neuronal
marker expression and astrocyte production, and I did not detect other FTDP-17T-relevant
phenotypes in MAPT-mutant cultures, perhaps due to the time points (50 and 80-100 days)
at which I examined them.
To investigate the effects of the N279K mutation independent of iPSC line genetic
background, I attempted to create isogenic iPSC lines using CRISPR. This was not successful,
but I obtained isogenic control and P301L iPSCs from Axol Bioscience, from which, along
with the patient-derived P301L MAPT-mutant iPSCs, I made cerebral organoids (COs).
Similar amounts of neuronal, astrocyte, and synaptic proteins were detected in the control
and MAPT-mutant COs, as were cortical layer markers indicating a forebrain-like fate.
Phosphorylation at the AT8 epitope was detected in the control and MAPT-mutant COs, as
was tau misfolding, detected using the MC-1 antibody.
In conclusion, some alterations similar to those observed in FTDP-17T brains can be
observed in monolayer iPSC-derived neurons and perhaps in iPSC-derived COs. However,
some phenotypes may be masked by experimental variability which needs to be addressed in
the future.Funded by the MRC-DTP and the Sackler Foundatio
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From chromatin to protein synthesis: the role of glutamate, amyloid beta and tau in Alzheimer’s disease
Alzheimer’s disease (AD) is the most common form of dementia, which is characterised by extracellular Aβ plaques and intracellular neurofibrillary tangles, comprised of fibrils of Aβ42 and tau protein, respectively. A species of tau protein localised to the nucleus has been discovered, but its role in AD is still unclear. Glutamate excitotoxicity, oxidative stress, DNA damage, alteration of the chromatin and nucleolar stress are key features of AD. The early stages of the disease are characterised by minimal neurodegeneration and altered protein synthesis machinery. The culprit (s) and molecular link between these changes and the role of nuclear tau are unclear. This work utilised glutamate stress and Aβ42 oligomers to investigate the involvement of nuclear tau in the chromatin alteration, nucleolar dysfunction, and downstream protein synthesis impairment that occurs in AD. This revealed that glutamate stress in SHSY5Y neuroblastoma cells results in oxidative stress, a nuclear upsurge of phosphorylated tau and delocalisation of nucleolar tau, alongside, DNA damage, heterochromatin loss, nucleolar stress and protein synthesis inhibition, partly through eIF2α phosphorylation. Likewise, short incubation of SHSY5Y cells with Aβ42 oligomers led to significant oxidative stress, with gradual accumulation of nucleolar stress, which resulted in altered transcription and processing of 45S pre-rRNA and decrease in protein synthesis, without DNA damage. Although both glutamate and Aβ ultimately decreased protein synthesis, Aβ incubation led to an increase in heterochromatin formation and a reduction in RNA synthesis without DNA damage, pointing to a different mechanism of toxicity by the Aβ and glutamate stress. To characterise a nuclear role for tau, this work localised tau in the nucleolus and heterochromatin in the SHSY5Y cells and the human brain, where it associates with TIP5 – a key player in heterochromatin formation. Accordingly, tau knockdown destabilises the heterochromatin and increases rDNA transcription, indicating that tau is essential for silencing of the rDNA and heterochromatin stability, similar to TIP5. Overall, this thesis provides evidence that implicates glutamate and Aβ toxicity in some of the changes that occur in the disease and specifically implicates Aβ42 as a key culprit that drives changes in the early stage of the disease. It also reveals a new role for tau in the nucleus and points to its pathological involvement in AD
The Human ARF Tumor Suppressor Regulates Drosha Nucleolar Localization and rRNA Processing Activity
Ribosomes are vital to the survival of a cell, as they are directly responsible for the synthesis of proteins, which perform critical cellular functions. As such, majority of the energy reserves in a proliferating cell are expended towards synthesis of ribosomes. Cancer cells, with their enhanced proliferation rates, tend to upregulate ribosome biogenesis in order to meet the demand for increased protein synthesis necessary to sustain rapid proliferation. Many of the oncogenes and tumor suppressors known to be deregulated in cancers are capable of positively and negatively regulating ribosome biogenesis, respectively. The ARF tumor suppressor strongly suppresses ribosome biogenesis, particularly in presence of oncogenic signaling. Furthermore, ARF is capable of negatively regulating multiple oncogenes capable of driving tumorigenesis partly through the ribosome biogenesis pathway. As ARF loss is a frequent occurrence in cancer cells, delineating the ARF-regulatory network and determining the impact of ARF loss on this network can give significant insight into the biology of ARF-deficient tumor cells. Expression of the RNase III enzyme, Drosha, has been reported to have prognostic value in multiple cancers. However, Drosha expression appears to have a dual nature in tumorigenesis, as both overexpression and loss of Drosha have been reported to have tumorigenic functions. Although the mechanistic basis of this apparent duality are not yet known, gaining a deeper understanding of Drosha\u27s functional capabilities can give us an insight into its role in tumorigenesis. Drosha performs critical functions in biogenesis of multiple RNA species within the cell, including ribosomal RNA (rRNA), micro RNA (miRNA) and messenger RNA (mRNA). Drosha\u27s role in miRNA biogenesis is the most studied and characterized aspect of its functions and can explain the tumor suppressive aspect of its dual nature; a global decrease in miRNAs has been reported to be part of tumor progression, and loss of Drosha has the potential to significantly deplete mature miRNA population within the cell. However, how overexpression of Drosha can drive tumorigenesis remains to be studied. As enhanced ribosome biogenesis is another feature of cancer cells and Drosha has been shown to aid in processing of r RNA, Drosha\u27s role in ribosome biogenesis pathway has the potential to function in an oncogenic manner. Therefore, further characterization of Drosha\u27s role in ribosome biogenesis can significantly enhance our understanding of its contribution to tumorigenesis. Recent studies in mouse cell lines revealed that ARF tumor suppressor is capable of negatively regulating Drosha expression in a translation-dependent manner. Given the entrenched role of ARF in inhibiting ribosome biogenesis, I hypothesized that ARF\u27s ability to regulate Drosha could impact Drosha\u27s functions in ribosome biogenesis pathway. I further hypothesized that Drosha overexpression could function in a pro-proliferative manner through the ribosome biogenesis pathway. The data presented in this Dissertation reveals that human p14ARF is capable of regulating Drosha protein expression in a dynamic and localized fashion; loss of ARF increases over all cellular Drosha protein levels and also the localization of Drosha to the nucleolus. ARF potentially regulates nucleolar localization of Drosha by sequestering it away from nucleolus, as we found that ARF immunoprecipitated with Drosha in RNA-independent manner. Furthermore, loss of ARF enhances ribosome biogenesis both at the level of 47s rRNA transcription and processing. Association of Drosha with precursor rRNAs was also enhanced in absence of ARF, suggesting that enhanced nucleolar localization of Drosha upon ARF loss contributes to rRNA processing. Drosha overexpression by itself was able to increase ribosome biogenesis, with a modest increase in 47s rRNA transcription and a faster accumulation of 28s and 18s rRNAs. Drosha overexpression led to an increase in ARF expression, although this induction of ARF was not sufficient to inhibit Drosha\u27s ability to enhance ribosome biogenesis and cell proliferation. However, overexpression of ARF negated proliferative enhancement induced by Drosha overexpression. These results point towards a cross-regulatory loop between ARF and Drosha, with functional impact on ribosome biogenesis
Mathematical model of interactions immune system with Micobacterium tuberculosis
Tuberculosis (TB) remains a public health problem in the world, because of the increasing prevalence and treatment outcomes are less satisfactory. About 3 million people die each year and an estimated one third of the world's population infected with Mycobacterium Tuberculosis (M.tb) is latent. This is apparently related to incomplete understanding of the immune system in infection M.tb. When this has been known that immune responses that play a role in controlling the development of M.tb is Macrophages, T Lymphocytes and Cytokines as mediators. However, how the interaction between the two populations and a variety of cytokines in suppressing the growth of Mycobacterium tuberculosis germ is still unclear. To be able to better understand the dynamics of infection with M tuberculosis host immune response is required of a model.One interesting study on the interaction of the immune system with M.tb mulalui mathematical model approach. Mathematical model is a good tool in understanding the dynamic behavior of a system. With the mediation of mathematical models are expected to know what variables are most responsible for suppressing the growth of Mycobacterium tuberculosis germ that can be a more appropriate approach to treatment and prevention target is to develop a vaccine. This research aims to create dynamic models of interaction between macrophages (Macrophages resting, macrophages activated and macrophages infected), T lymphocytes (CD4 + T cells and T cells CD8 +) and cytokine (IL-2, IL-4, IL-10,IL-12,IFN-dan TNF-) on TB infection in the lung. To see the changes in each variable used parameter values derived from experimental literature. With the understanding that the variable most responsible for defense against Mycobacterium tuberculosis germs, it can be used as the basis for the development of a vaccine or drug delivery targeted so hopefully will improve the management of patients with tuberculosis. Mathematical models used in building Ordinary Differential Equations (ODE) in the form of differential equation systems Non-linear first order, the equation contains the functions used in biological systems such as the Hill function, Monod function, Menten- Kinetic Function. To validate the system used 4th order Runge Kutta method with the help of software in making the program Matlab or Maple to view the behavior and the quantity of cells of each population
Assessment of histopathological methods of evaluating response to neoadjuvant therapy in oesophageal and gastric adenocarcinoma
Upper gastrointestinal tract (GIT) cancers usually receive neoadjuvant therapy prior to surgery. The histological assessment of this response and if this can be predicted on the pre-treatment biopsy are the subject of this thesis. The first study assessed the inter- and intra-observer variation amongst pathologists in evaluating the degree of regression using the Mandard scoring system. The results showed that the reproducibility of this system was only fair to moderate in both cases of inter- and intra-observer testing. The second study examined the levels of expression of selected tumour markers before and after neoadjuvant chemotherapy. These included markers monitoring apoptosis (p53 and bcl-2), proliferation (Ki-67), angio- and lymphangio-genesis (VEGF, CD-31 and LYVE-1). The levels of expression in these markers were measured in the pre-treatment biopsies, to monitor if they could predict the response to neoadjuvant therapy. It was found that when the panel of chosen markers being used together, delivered a much higher power of prediction rather than adopting only one marker, where the collective power of prediction was 80.6%, whereas individually, the power of prediction ranged between 24.6% (VEGF) and 60.7% (Ki-67). The third study explored the use of digital image analysis in assessing the response to neoadjuvant therapy. It was found that while this technique paralleled the Mandard scoring system, it delivered a more objective and reproducible assessment. On the basis of these results I suggest that image analysis should be used to assess tumour regression especially in the context of clinical trials. In this retrospective study it has been shown that the pre-treatment biopsy can predict the degree of regression