CD4+ Cell Development, Function & Dysregulation in Allergy and Autoimmune Diseases
CD4+ Cell Development, Function & Dysregulation in Allergy and Autoimmune Diseases The helper T (TH) cells in the body are central to all branches of the immune system. They are very aggressive cells, due to their role as 'molecular guardians of the body' and so they must be regulated and controlled. If this regulation or self-tolerance breaks down, then this provides a window for the development of allergy, being a "disease following a response by the immune system to an otherwise innocuous antigen" [12], or autoimmunity, where the body's immune system targets self antigens. Before an understanding of the role of different CD4+ cells in immunopathology can be achieved, an appreciation of the different characteristics and interactions of these cells must first be considered. After preparation of antigen onto a major histocompatibility complex-II (MHC-II), an antigen presenting cell (APC), typically a dendritic cell (DC) or macrophage, will present this to a naive TH cell. Depending on what type of pathogen has been encountered, the APC will stimulate the polarisation of the naive cell to one subset of TH cells. This is achieved by the release of specific cytokines from the APC to the TH cell, and the subsets of CD4+ cells are each defined by their unique surface receptors, the cytokines they release and by the types of invaders they target. The first subset to be
Muscular Dystrophy
Muscular Dystrophy Essay Discuss: (a) the way in which a mutation in the gene encoding the protein dystrophin leads to defects in the muscle cell membrane of patients with Duchenne muscular dystrophy; and, (b) the practical issues involved in potential treatments and cures. The dystrophin protein is a large rod shaped protein with a molecular weight of 427 kDa. The gene itself is 2.4 million bp long making it one of the largest in the human genome, the mRNA transcribed from it is reduced to 14 000 bp due to the many exons it is encoded by. The gene is located on the short arm of the X chromosome at position Xp21.2 bestowing upon it sex linked heredity. Muscular dystrophies in general are rarely manifested in females and this is the case with Duchenne Muscular Dystrophy (DMD). In two thirds of all cases a mutated form of the dystrophin gene is passed on to sons from the mother, however, in the remaining third the deficiency is due to a novel mutation. The high mutatation rate (possibly 1 in 10 000) is thought to be a product of the genes extraordinary length and this can cause problems with genetic counselling. Dystrophin is made up of (3700 amino acids (aa's) and has four structural domains: * N-terminal: associates with F-actin in the sub-sarcolemmal cytoskeleton * Rod domain: 25 repeats of 109 aa's in a triple helix * Cysteine rich domain: binds to sarcolemmal
Calcium transport study of SF-9 lepidopteran cells and bull frog sympathetic ganglion cells
Calcium transport study of SF-9 lepidopteran cells and bull frog sympathetic ganglion cells ABSTRACT The intracellular calcium level and the calcium efflux of the bull-frog sympathetic ganglion cells (BSG) and the SF-9 lepidopteran ovarian cells were investigated using a calcium-sensitive fluorescence probe fura-2. It was found that the intracellular calcium levels were 58.2 and 44.7 nM for the BSG cells and SF-9 cells respectively. The calcium effluxes following zero calcium solution were 2.02 and 1.33 fmole·cm-2·s-1 for the BSG cells and SF-9 cells. The calcium effluxes following sodium orthovanadate (Na2VO4) in zero calcium solution were 6.00 and 0.80 fmole·cm-2·s-1 for the BSG cells and the SF-9 cells. The SF-9 cells also lost the ability to extrude intracellular calcium after 2-3 applications of Na2VO4 while the BSG cells showed no apparent lost of calcium extruding abilities for up to 4 applications of Na2VO4. INTRODUCTION Spodoptera frugiperda clone 9 (SF-9) cells are a cultured insect cell line derived from the butterfly ovarian tissue. SF-9 cells are used by molecular biologists for the studies of gene expression and protein processing (Luckow and Summers, 1988). However, there is not much known about these cells' basic biophysiology. Since calcium is involved in many cells' activities such as acting as a secondary messenger, it is important for cells to
To examine the evidence for a link between stress and ill health
This essay is going to examine the evidence for a link between stress and ill health. It will include sections on what stress is, how it is caused and its effects on the body and the mind. This essay is going to look at and evaluate different psychologist's views on stress and the effects it has on the body and mind. There are three main ways at looking at stress. Firstly, as an external stimulus which places a strain on the individual, for example, taking an exam, moving house, divorce or a new job. Secondly, as an internal state of psychological and physiological change in response to a stressor. In this sense stress is something happening inside the person rather than an outside force acting on the person. It is the psychological and physiological changes produced by a stressor. These changes are known as the stress response. Psychological aspects of the stress response may include a state of tension involving emotions such as fear, anxiety and anger. Examples of physiological aspects of the stress response include an increase in heart rate and the release of sugar into the bloodstream. Thirdly, stress can be seen as a transaction between an individual and their environment. This transaction results in a stress response if the individual believes they cannot cope with the demands they see placed upon them, for example, one person may see a divorce as a calamity,
The Ras Superfamily
The Ras Superfamily: Ubiquitous Regulators of Cell Function Monomeric GTPase Ras proteins control many cellular activities and functions. They fluctuate from an inactive GDP containing state to an active GTP containing state, and this activation is lost due to the GTPase activity of the protein. They are very potent transducers of signals, and therefore this ability to transfuse signals is tightly controlled by other adaptor proteins, such as Guanine nucleotide exchange factors (GEFs), and GTPase activating proteins (GAPs). Loss of such control leads to hyperactivation or loss of ability in certain cellular functions, such as cellular growth, migration, and vesicular transport. This has been found commonly in human cancers, and novel treatments may require targeting the pathways and molecules discussed in this dissertation. The Ras superfamily is a group of monomeric GTPase proteins which all share common features in structure and activity with Ras, a protein discovered in 1977 in association with transformed rat cells. The variants then discovered were named H-Ras, and K-Ras, and the third Ras isoform was discovered shortly after in 1983, and was called N-Ras.1-3 These are encoded by 3 proto-oncogenes, H-RAS, K-RAS and N-RAS, and selective cleavage of K-RAS's product gives rise to 2 proteins, K-Ras4A, and K-Ras4B.4-6 There have since been over 150 further 'Ras-like'
The structure and functions of body tissues.
UNIT 2 - Human Physiology Assignment 1 - THE STRUCTURE AND FUNCTIONS OF BODY TISSUES Histology is the name for the study of tissues. A tissue is a group of cells which forms a specialised function. There are many different types of tissue and one type of tissue may be found in many parts of the body. In the body we have four main types of tissue which are: * Epithelial * Connective * Muscle * Nervous All these different types of tissue are needed in order for the body to function. All of these tissues have different characteristics and functions. The first type of tissue to look at is: Epithelial Tissue There are 6 main types of epithelial tissue: * Squamous epithelium * Cubodial epithelium * Columnar epithelium * Ciliated epithelium * Compound transitional epithelium * Glandular epithelium Squamous Epithelium Simple squamous These are usually made up of thin flat scale like cells, which rest on the basement of the membrane. This type of tissue can be found in renal capsules of the kidneys, alveoli of the lungs and blood capillary walls. They are usually found in these areas as the thinness of the cells allows diffusion of materials through them. Therefore the main functions are to reduce friction, and to perform absorption and secretion. Stratified squamous Stratified squamous are made up of several layers of cells. They are like simple sqarmous cells
laboratory equipment - Discuss the principles behind, and the use of - The Embedding Station - The Faxitron
Sandra Richards 01.12.02 AWPL Ass.1 Essay Discuss the principles behind, and the use of: a) The Embedding Station b) The Faxitron Introduction This essay will attempt to explain the scientific, technological principles and the practical uses of the above mentioned pieces of laboratory equipment highlighting health and safety issues where appropriate. The principle of the embedding station is to accurately and precisely orientate a histological specimen into a block of paraffin wax; this will allow the support and firm hold of the tissue sample so that fine cutting of thin sections for histological diagnostic purposes can ensue. The equipment required is the Tissue tek / R A LAMB embedding station, tissue moulds (assorted sizes) and speci-ceps heated forceps. The tissue moulds are of various sizes to allow enough embedding medium to fully surround and support the tissue sample. Heated forceps are used so that any wax coming into contact with them is kept at a molten state which can be easily removed using a paper tissue, cold wax will adhere to the forceps making it very difficult to manoeuvre tissue into the correct orientation as there would be a build up of solid wax. The wax used as the embedding medium in this particular laboratory is paraffin wax. This type of wax is molten above 60oC and is in the solid state at room temperature. Its hardness is ideal
To what extent can autoimmunity be described as the breakdown of self tolerance and how far have animal models contributed to our understanding of human autoimmune disease?
Felicity J Walker-Buckton Magdalen College To what extent can autoimmunity be described as the breakdown of self tolerance and how far have animal models contributed to our understanding of human autoimmune disease? Introduction Autoimmunity is the propagation of adaptive immunity specific for self antigens. The obligation of preventing such an occurrence was recognised by Ehrlich who described the possibility of 'Horror autotoxicus'. In his 'clonal selection' theory, Burnet proposed that tolerance to self antigens is achieved by clonal deletion or inactivation of developing lymphocytes in the thymus or the periphery. In the present day it is realised that this self/non-self reductionism is insufficient to explain a number of characteristics of the immune system; firstly, the content of self changes in host life, for example the production of sperm at puberty in males; secondly, most of self antigens, e.g. heat shock proteins are not absolutely different from non-self structures; thirdly, recognition of self is indeed required for the continued survival of mature lymphocytes; fourthly, antigenic recognition by MHC is promiscuous and imprecise and finally (and perhaps most convincingly); autoreactive T and B cells are present even in healthy individuals. These considerations indicate that antigens (Ag) can reside in a 'no mans land' of the immune system in which they
Contractions in skeletal muscle are regulated by stimulus strength, stimulus frequency, and sarcomere length.
Contractions in skeletal muscle are regulated by stimulus strength, stimulus frequency, and sarcomere length 425-55-6522 BIOL 4161 November 2, 2004 Abstract The electrical responses and muscle contractions of the skeletal muscle of Rana pippiens in response to various stimulus strengths, stimulus frequencies, and muscle stretch were studied in this experiment. We identified the minimum stimulus voltage required to produce a muscle twitch. Electromyogram (EMG) generally increased in response to increasing stimulus strength. Recordings of contraction force and the duration of the muscle twitch showed no distinct pattern over increasing stimulus strength. The time between the stimulus pulse and the start of the contraction decreased with increasing stimulus strength. The time delay from the start of the muscle contraction until the maximum tension was reached generally decreased with increasing stimulus strength. Baseline tension of the muscle increased with increasing frequency of a stimulus pulse. Change in baseline tension of the muscle showed a general increase with increasing muscle stretch up to a certain point. The muscle contraction force also increased with increasing change in muscle length up to a point. In this experiment we learned about skeletal muscle contraction in response to changes in stimulus strength and frequency and sarcomere length.
The clinical skill this reflective assignment will refer to is the measurement of blood pressure which was one of the many skills I had to perform on a daily basis.
Student number: 1103661 Assessment number F03314 Reflective skills report The purpose of this assignment is to reflect on a clinical skill which has been performed whilst out in clinical practice. The clinical skill this reflective assignment will refer to is the measurement of blood pressure which was one of the many skills I had to perform on a daily basis. Being on a rehabilitation ward for my placement gave me the opportunity to perform a variety of clinical skills. To help me reflect and explore my experience of undertaking my chosen skill, I will be using the Gibbs’ model of reflection (Gibbs 1988). A reflective model such as this has been used because, as suggested by Hargreaves (1997), reflective models are a tool that is believed to result in both improvement in patient care and professional development. Gibbs model of reflection incorporates the following: description, feelings, evaluation, analysis, conclusion and an action plan (Gibbs 1988). Throughout this assignment I will be referring to the student guidelines relating to the maintenance of confidentiality, which states that all relevant information gained is accurate and used to the purpose of the assignment only, in this case all personal details of the patient I will be discussing which identifies her will be excluded from the text. Also In accordance with the Nursing and Midwifery Councils (2008) Code