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Search Results: 1 - 10 of 400839 matches for " M Tomlinson "
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Current perspectives on rosuvastatin
Hu M,Tomlinson B
Integrated Blood Pressure Control , 2013,
Abstract: Miao Hu, Brian Tomlinson Department of Medicine and Therapeutics, Chinese University of Hong Kong, Shatin, Hong Kong Abstract: Rosuvastatin is one of the most potent statins available for reducing circulating low-density lipoprotein cholesterol (LDL-C) levels, which enables more high-risk patients to achieve their lipid goals. Its favorable balance of effects on atherogenic and protective lipoproteins and its pleiotropic effects, including anti-inflammatory and antioxidant effects and improvement in endothelial dysfunction, are associated with slowing of progression of atherosclerosis within the artery wall and have been translated into clinical benefits for cardiovascular outcomes. This review provides an update on the safety and the efficacy of rosuvastatin in recent large clinical trials. It appears that rosuvastatin has a beneficial effect on the progression of atherosclerosis across the clinical dosage range of 2.5–40 mg. It reduced cardiovascular events in relatively low-risk subjects with elevated high-sensitivity C-reactive protein and normal low-density lipoprotein cholesterol. As with other statins, rosuvastatin did not show overall benefit in terms of survival in patients with heart failure, but certain clinical or biochemical markers reflecting underlying disease characteristics may help to identify subgroups of patients that benefit from statin therapy. In patients with end-stage renal disease undergoing chronic hemodialysis, rosuvastatin had no effect on reducing cardiovascular events. Although there is a slightly increased risk of incident diabetes with this class of agents, the absolute benefits of statin therapy on cardiovascular events overweigh the risk in patients with moderate or high cardiovascular risk or with documented cardiovascular disease. As with other statins, rosuvastatin is an appropriate therapy in addition to antihypertensive treatment to reduce cardiovascular risk in hypertensive patients. Keywords: atherosclerosis, cardiovascular disease, lipids, rosuvastatin
Suicide ideation, depression and HIV among pregnant women in rural South Africa  [PDF]
Tamsen J. Rochat, Ruth M. Bland, Mark Tomlinson, Alan Stein
Health (Health) , 2013, DOI: 10.4236/health.2013.53A086
Abstract:

Background: Despite public perception to the contrary, pregnancy does not offer a protective effect for suicide ideation. In low and middle income countries (LMIC) multiple concurrent risk factors including unplanned pregnancies, testing for HIV, intimate partner violence and depression may increase suicide risk among pregnant women. We examine suicide ideation among women attending routine antenatal care in rural South Africa. Method: A consecutive series of 109 women in the second half of pregnancy were enrolled in a cross-sectional study at a large primary health care facility in a rural area of KwaZulu-Natal with high HIV prevalence. Using a mixed-methods approach, women were assessed using the Major Depression Section of the Structured Clinical Interview for Depression (SCID) for DSM-IV diagnosis; qualitative interview data were collected on women’s experiences of suicide ideation and plans. Women were assessed two weeks after routine HIV testing as part of Prevention of Mother-to-Child Transmission (PMTCT) screening. Results: Both HIV-positive (49/109) and HIV-negative (60/109) women were assessed. Depression was high (51/109, 46.7%) and equally common amongst HIV-positive and negative women. Suicide ideation was high (30/109, 27.5%) with thoughts of self harm closely linked to suicide plans. Age, previous history of depression and current depression were significantly associated with suicide ideation. Close to equal numbers of HIV-positive and negative women were suicidal. Suicide methods were frequently violent and most women cited family and partnership conflict related to an unplanned pregnancy or their newly HIV-positive status as triggers to their suicide ideation. Conclusions: Rates of suicide ideation among pregnant women testing for HIV are high. Testing HIV-positive causes considerable distress, and among HIV-negative women unplanned and unwanted pregnancies are important risk factors for suicide ideation. Pregnancy brings women into increased contact with the health services with important opportunities for prevention and intervention.

Protein profiling comes of age
Ian M Tomlinson, Lucy J Holt
Genome Biology , 2001, DOI: 10.1186/gb-2001-2-2-reviews1004
Abstract: For the past 10 years there has been considerable interest in the creation of high-density arrays of nucleic acids for use in genomics and 'transcriptomics'. Since the first model experiments in academic laboratories [1], the number of spots on each array has steadily grown whilst the overall size of the arrays has shrunk (see [2,3,4]). Today's DNA microarray is the size of a thumbnail and can contain over 10,000 different oligonucleotides. The pages of scientific journals are peppered with advertisements touting robots for probing DNA microarrays, machines for imaging DNA microarrays, software for analyzing DNA microarrays and, of course, the DNA microarrays themselves; the estimated annual market for the technology is in excess of $527 million [5]. The application of DNA microarrays is equally widespread, ranging from DNA sequencing [6,7] to the genotyping of disease genes [8,9,10].It has long been the goal of molecular biologists to develop a technology that can quantify, in a reliable and reproducible manner, the expression level of every individual protein in a tissue sample. DNA microarrays have been used extensively for the analysis of RNA in cellular extracts, from which the expression of individual proteins can be inferred by assessing the levels of their corresponding mRNAs [11,12,13] (see [14] for a review). Changes at the mRNA level, however, are not necessarily proportional to changes at the protein level because of differences in rates of protein translation and degradation. Furthermore, nucleotide screens are unable to provide information on the post-translational modifications of a protein, which may be critical for a protein's function. After all, it is the protein and not the mRNA that provides cellular function, whether it be for communication, metabolism or building cellular architecture.Although two-dimensional pulse-field gel electrophoresis (2D PFGE) can be used to analyze the proteins expressed in different cellular extracts directly, it requ
A non-linear mathematical model of cell turnover, differentiation and tumorigenesis in the intestinal crypt
Alberto d'Onofrio,Ian P. M. Tomlinson
Quantitative Biology , 2013, DOI: 10.1016/j.jtbi.2006.08.022
Abstract: We present a development of a model of the relationship between cells in three compartments of the intestinal crypt: stem cells, semi-differentiated cells and fully differentiated cells. Stem and semi-differentiated cells may divide to self-renew, undergo programmed death or progress to semi-differentiated and fully differentiated cells respectively. The probabilities of each of these events provide the most important parameters of the model. Fully differentiated cells do not divide, but a proportion undergoes programmed death in each generation. Our previous models showed that failure of programmed death - for example, in tumorigenesis - could lead either to exponential growth in cell numbers or to growth to some plateau. Our new models incorporate plausible fluctuation in the parameters of the model and introduce non-linearity by assuming that the parameters depend on the numbers of cells in each state of differentiation. We find that the model is characterized by bifurcation between increase in cell numbers to stable equilibrium or 'explosive' exponential growth; in a restricted number of cases, there may be multiple stable equilibria. Fluctuation in cell numbers undergoing programmed death, for example caused by tissue damage, generally makes exponential growth more likely, as long as the size of the fluctuation exceeds a certain critical value for a sufficiently long period of time. In most cases, once exponential growth has started, this process is irreversible. In some circumstances, exponential growth is preceded by a long plateau phase, of variable duration, mimicking equilibrium: thus apparently self-limiting lesions may not be so in practice.
Near Maximum-Likelihood Performance of Some New Cyclic Codes Constructed in the Finite-Field Transform Domain
C. Tjhai,M. Tomlinson,R. Horan,M. Ambroze,M. Ahmed
Mathematics , 2005,
Abstract: It is shown that some well-known and some new cyclic codes with orthogonal parity-check equations can be constructed in the finite-field transform domain. It is also shown that, for some binary linear cyclic codes, the performance of the iterative decoder can be improved by substituting some of the dual code codewords in the parity-check matrix with other dual code codewords formed from linear combinations. This technique can bring the performance of a code closer to its maximum-likelihood performance, which can be derived from the erroneous decoded codeword whose euclidean distance with the respect to the received block is smaller than that of the correct codeword. For (63,37), (93,47) and (105,53) cyclic codes, the maximum-likelihood performance is realised with this technique.
Improved Iterative Decoding for Perpendicular Magnetic Recording
E. Papagiannis,C. Tjhai,M. Ahmed,M. Ambroze,M. Tomlinson
Mathematics , 2005,
Abstract: An algorithm of improving the performance of iterative decoding on perpendicular magnetic recording is presented. This algorithm follows on the authors' previous works on the parallel and serial concatenated turbo codes and low-density parity-check codes. The application of this algorithm with signal-to-noise ratio mismatch technique shows promising results in the presence of media noise. We also show that, compare to the standard iterative decoding algorithm, an improvement of within one order of magnitude can be achieved.
GF(2^m) Low-Density Parity-Check Codes Derived from Cyclotomic Cosets
C. Tjhai,M. Tomlinson,R. Horan,M. Ambroze,M. Ahmed
Mathematics , 2005,
Abstract: Based on the ideas of cyclotomic cosets, idempotents and Mattson-Solomon polynomials, we present a new method to construct GF(2^m), where m>0 cyclic low-density parity-check codes. The construction method produces the dual code idempotent which is used to define the parity-check matrix of the low-density parity-check code. An interesting feature of this construction method is the ability to increment the code dimension by adding more idempotents and so steadily decrease the sparseness of the parity-check matrix. We show that the constructed codes can achieve performance very close to the sphere-packing-bound constrained for binary transmission.
Idempotents, Mattson-Solomon Polynomials and Binary LDPC codes
R. Horan,C. Tjhai,M. Tomlinson,M. Ambroze,M. Ahmed
Mathematics , 2005,
Abstract: We show how to construct an algorithm to search for binary idempotents which may be used to construct binary LDPC codes. The algorithm, which allows control of the key properties of sparseness, code rate and minimum distance, is constructed in the Mattson-Solomon domain. Some of the new codes, found by using this technique, are displayed.
On the Weight Distribution of the Extended Quadratic Residue Code of Prime 137
C. Tjhai,M. Tomlinson,M. Ambroze,M. Ahmed
Mathematics , 2008,
Abstract: The Hamming weight enumerator function of the formally self-dual even, binary extended quadratic residue code of prime p = 8m + 1 is given by Gleason's theorem for singly-even code. Using this theorem, the Hamming weight distribution of the extended quadratic residue is completely determined once the number of codewords of Hamming weight j A_j, for 0 <= j <= 2m, are known. The smallest prime for which the Hamming weight distribution of the corresponding extended quadratic residue code is unknown is 137. It is shown in this paper that, for p=137 A_2m = A_34 may be obtained with out the need of exhaustive codeword enumeration. After the remainder of A_j required by Gleason's theorem are computed and independently verified using their congruences, the Hamming weight distributions of the binary augmented and extended quadratic residue codes of prime 137 are derived.
A New Non-Iterative Decoding Algorithm for the Erasure Channel : Comparisons with Enhanced Iterative Methods
J. Cai,C. Tjhai,M. Tomlinson,M. Ambroze,M. Ahmed
Mathematics , 2005,
Abstract: This paper investigates decoding of binary linear block codes over the binary erasure channel (BEC). Of the current iterative decoding algorithms on this channel, we review the Recovery Algorithm and the Guess Algorithm. We then present a Multi-Guess Algorithm extended from the Guess Algorithm and a new algorithm -- the In-place Algorithm. The Multi-Guess Algorithm can push the limit to break the stopping sets. However, the performance of the Guess and the Multi-Guess Algorithm depend on the parity-check matrix of the code. Simulations show that we can decrease the frame error rate by several orders of magnitude using the Guess and the Multi-Guess Algorithms when the parity-check matrix of the code is sparse. The In-place Algorithm can obtain better performance even if the parity check matrix is dense. We consider the application of these algorithms in the implementation of multicast and broadcast techniques on the Internet. Using these algorithms, a user does not have to wait until the entire transmission has been received.
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