Toxicology of Biomedical Polymers

This paper deals with the various types of polymers, used in the fabrication of medical devices, their diversity of applications and toxic hazards which may arise out of their application. The potential toxicity of monomers and the various additives used in the manufacture of biomedical polymers have been discussed along with hazards which may arise out of processing of devices such as sterilization. The importance of quality control and stringent toxicity evaluation methods have been emphasised since in our country, at present, there are no regulations covering the manufacturing and marketing of medical devices. Finally the question of the general and subtle long term systemic toxicity of biomedical polymers have been brought to attention with the suggestion that this question needs to be resolved permanently by appropriate studies

Hybrid Genetic Algorithm for Medical Image Feature Extraction and Selection

AbstractFor a hybrid medical image retrieval system, a genetic algorithm (GA) approach is presented for the selection of dimensionality reduced set of features. This system was developed in three phases. In first phase, three distinct algorithm are used to extract the vital features from the images. The algorithm devised for the extraction of the features are Texton based contour gradient extraction algorithm, Intrinsic pattern extraction algorithm and modified shift invariant feature transformation algorithm. In the second phase to identify the potential feature vector GA based feature selection is done, using a hybrid approach of “Branch and Bound Algorithm” and “Artificial Bee Colony Algorithm” using the breast cancer, Brain tumour and thyroid images. The Chi Square distance measurement is used to assess the similarity between query images and database images. A fitness function with respect Minimum description length principle were used as initial requirement for genetic algorithm. In the third phase to improve the performance of the hybrid content based medical image retrieval system diverse density based relevance feedback method is used. The term hybrid is used as this system can be used to retrieve any kind of medical image such as breast cancer, brain tumour, lung cancer, thyroid cancer and so on. This machine learning based feature selection method is used to reduce the existing system dimensionality problem. The experimental result shows that the GA driven image retrieval system selects optimal subset of feature to identify the right set of images

Epigenetics of a tandem DNA repeat: chromatin DNaseI sensitivity and opposite methylation changes in cancers

DNA methylation and chromatin DNaseI sensitivity were analyzed in and adjacent to D4Z4 repeat arrays, which consist of 1 to ∼100 tandem 3.3-kb units at subtelomeric 4q and 10q. D4Z4 displayed hypomethylation in some cancers and hypermethylation in others relative to normal tissues. Surprisingly, in cancers with extensive D4Z4 methylation there was a barrier to hypermethylation spreading to the beginning of this disease-associated array (facioscapulohumeral muscular dystrophy, FSHD) despite sequence conservation in repeat units throughout the array. We infer a different chromatin structure at the proximal end of the array than at interior repeats, consistent with results from chromatin DNaseI sensitivity assays indicating a boundary element near the beginning of the array. The relative chromatin DNaseI sensitivity in FSHD and control myoblasts and lymphoblasts was as follows: a non-genic D4Z4-adjacent sequence (p13E-11, array-proximal)> untranscribed gene standards > D4Z4 arrays> constitutive heterochromatin (satellite 2; P < 10−4 for all comparisons). Cancers displaying D4Z4 hypermethylation also exhibited a hypermethylation-resistant subregion within the 3.3-kb D4Z4 repeat units. This subregion contains runs of G that form G-quadruplexes in vitro. Unusual DNA structures might contribute to topological constraints that link short 4q D4Z4 arrays to FSHD and make long ones phenotypically neutral

Autoimmune Neuromuscular Disorders in Childhood

Autoimmune neuromuscular disorders in childhood include Guillain-Barré syndrome and its variants, chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), juvenile myasthenia gravis (JMG), and juvenile dermatomyositis (JDM), along with other disorders rarely seen in childhood. In general, these diseases have not been studied as extensively as they have been in adults. Thus, treatment protocols for these diseases in pediatrics are often based on adult practice, but despite the similarities in disease processes, the most widely used treatments have different effects in children. For example, some of the side effects of chronic steroid use, including linear growth deceleration, bone demineralization, and chronic weight issues, are more consequential in children than in adults. Although steroids remain a cornerstone of therapy in JDM and are useful in many cases of CIDP and JMG, other immunomodulatory therapies with similar efficacy may be used more frequently in some children to avoid these long-term sequelae. Steroids are less expensive than most other therapies, but chronic steroid therapy in childhood may lead to significant and costly medical complications. Another example is plasma exchange. This treatment modality presents challenges in pediatrics, as younger children require central venous access for this therapy. However, in older children and adolescents, plasma exchange is often feasible via peripheral venous access, making this treatment more accessible than might be expected in this age group. Intravenous immunoglobulin also is beneficial in several of these disorders, but its high cost may present barriers to its use in the future. Newer steroid-sparing immunomodulatory agents, such as azathioprine, tacrolimus, mycophenolate mofetil, and rituximab, have not been studied extensively in children. They show promising results from case reports and retrospective cohort studies, but there is a need for comparative studies looking at their relative efficacy, tolerability, and long-term adverse effects (including secondary malignancy) in children