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Example research essay topic: Breast Cancer Ten Minute - 1,507 words

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A lot of work has been done recently to establish a Human Genome Model, a genetic map, physical map and comparative DNA sequence of human chromosomes. This work with the Human Genome Model cannot be achieved without a small part upon the parallel implementation of gene mapping projects in other species. One of these other species which has been associated with the human recently has been the feline (1). With exception to the primates, of the non primate mammalian species with developing comparative gene maps, the feline gene map (Felis Cat) displays the highest level of synthetic conservation with that of the humans gene map. The comparison of the human and feline map has shown many similarities between the human and feline, one of the most important similarities being the analogous relationship between felines and human diseases (2). < b> Her 2 /neu Gene< /b> The human epidermal growth factor receptor 2 (Her 2) /neu proto-oncogene, sometimes seen referred to as c-erbB 2, encodes a 185 kDa transmembrane tyrosine kinase receptor protein with homology to the epidermal growth factor (egfr) receptor (3). The Her 2 /neu gene has an important role in normal cell growth and differentiation (6, 7).

The egfr family of receptors (including the Her 2 /neu gene) is involved in cell-to-cell and cell-to-stroma communication primarily through a process known as signal transduction, in which external growth factors, or ligands, affect the transcription of various genes by phosphorylation or dephosphorylating a series of transmembrane proteins and intracellular signaling intermediates, many of which possess enzymatic activity (4). Receptor activation requires three variables, a ligand, a receptor and a dimerization partner (5). After a ligand binds to a receptor, that receptor must interact with another receptor of identical or related structure in a process known as dimerization in order to trigger phosphorylation and activate signaling cascades (picture 2 b). The activity of Her 2 /neu transmembrane receptor seems to be regulated by a 30 kDa glycoprotein ligand (8).

This phosphorylation and activation of signaling cascades will sometimes cause gene alterations, including gene amplification (9). < b> p 185 Her 2 < /b> All normal cells contain two copies of the her 2 gene and produce low levels of protein, also referred to as p 185 Her 2 (10). It is mostly the gene amplification of the Her 2 /neu gene that has caused p 185 Her 2 protein to overexpression in many cells. This overexpression is almost always the result of gene amplification (6, 11 - 14), an increase in the number of gene copies in the cell, being reported as occuring between 90 and 95 percent of the time (11 - 16). Normal breast cancer cells have 20, 000 - 50, 000 Her 2 receptors, while tumor cells that over express Her 2 -neu can have up to 2, 000, 000 receptors (14). < b> Her 2 /neu in Breast Cancer< /b> Her 2 /neu overexpression occurs in many types of cancers, including breast cancer (11, 14, 17 - 25). Her 2 /neu has been reported to be overexpressed in approximately 20 - 30 % of breast cancer cases. Her 2 /neu overexpression in breast cancer cases has been associated with poor clinical outcome, or poor prognosis, aggressive tumor growth and metastatic activity, which, predicted overall survival (OS) and disease-free survival (DFS) of patients with breast cancer.

This was first reported by Season et al in 1987 (11), and has been confirmed in numerous recent publications. Studies that have sought confirming Seasons assumption of poor clinical outcome have found that overexpression of the p 185 Her 2 protein has actually reported worse clinical outcome (worse OS and DFS) than cases that did not over express the her 2 protein as much, or did not express it at all (11, 26 - 28). Amplification of the Her 2 /neu gene that causes the Her 2 protein overexpression has been an early event in the development of cancer (29). It has therefore recently become a major interest to focus on the role of Her 2 /neu status in breast cancer as a predictor of response or resistance to various forms of systemic therapy. < b> Detection of Her 2 /neu in Breast Cancer< /b> Both morphology-based and molecular-based techniques have been used to measure Her 2 /neu status in breast cancer clinical samples (10 - 11, 20, 22, 24, 26 - 27) ).

Some of the most popular techniques for detecting Her 2 /neu include different two types of blots: fluorescent in situ hybridization (FISH), and immunohistochemistry (IHC). FISH and IHC have become the two most commonly used assays, each having its own specific purpose. FISH specializes in detecting the amplification of the Her 2 gene, whereas IHC specializes in detecting the overexpression of the Her 2 protein (30). Since gene amplification is the most common cause of the protein overexpression, either method is sufficient enough to determine the clinical significance of any tissue sample with over amplified Her 2 /neu or overexpressed p 185 Her 2; however it has been found that IHC has become the more common process of the two used, especially on formalin-fixed paraffin-embedded samples of breast cancer (31 - 34). Numerous studies have reported IHC to be the most commonly used method for evaluating the overexpressed Her 2 /neu protein on formalin-fixed paraffin-embedded samples of breast cancers. However, because various tissue fixation protocols, assay methods, Her 2 /neu antibodies, and scoring systems are in use, variability in Her 2 /neu IHC results has become a matter of legitimate concern.

Despite this concern for variability in results, IHC staining is particularly useful because it reveals Her 2 /neu protein overexpression in individual tumor cells. IHC for Her 2 /neu protein overexpression is also the most attractive routine test based on issues of cost, convenience and biological relevance. IHC uses a combination of reagents with specified anti-protein antibodies to detect the overexpressed protein (30). IHC is understood through a scoring system of passes, ranging from 0 + - 3 +, 0 being the least positive, 3 being the most positive. Due to the significance of the present situation with Her 2 /neu protein overexpression, it is important that methods for decreasing the amount of Her 2 /neu expression in breast cancer be decreased. < b> Objective< /b> The purpose of this experiment is to detect the overexpression of the p 185 Her 2 protein in feline tissue by using the process of immunohistochemistry. This information could possibly lead to a breakthrough in Her 2 /neu research and eventually a method for decreasing the overexpressed Her 2 protein in breast cancer. < b> Materials and Methods< /b> Thirty different cases were collected from the Animal Medical Center Surgical's database; these cases were previous surgical biopsies with records of felines that had breast cancer.

Each case was kept in a formalin-fixed paraffin-embedded wax box, for storage. The histopathological lab of the Animal Medical Center then went ahead and cut 5 m sections of the tissue and put the cuts onto slides. Once the slides are ready, they are prepared for immunohistochemistry. The slides are first put through a preliminary pretreatment. This pretreatment is simply soaking the slides in a solution of 10 X Reveal (Biocare Medical) of pH 6. 0 diluted to 1 X.

The purpose of the pretreatment is to 1) expose the previously wax covered tissue for the run and 2) break the cross links formed by the formalin. The pretreatment consists of a fifteen minute bath in the pH 6. 0; during the fifteen minutes, the slides are pressurized and closed into a de-cloaking chamber (also Biocare Medical) at 120 C (the high temp. breaks the cross links). Following the fifteen minute period comes a 5 minute cool down period in the pH 6. 0 solution, a five minute H 2 O bath at pH 7. 0 and an additional five minute cool down period to let slides cool off.

Once pretreatment is completed, slides are put into the Optimal Plus (BioGenex) IHC machine. Parameters for each slide are set into the machines memory. These parameters (which can be seen in picture 2) include a ten minute incubation of peroxidase (H 2 O 2) block, an hour incubation time of the primary antibody (1), a twenty minute incubation of the secondary antibody (multi-link; 2), a twenty minute incubation of label horse radish peroxidase (HRP; 3), a ten minute incubation time of chromogen di amino benzidine (DAB; 4) and finished with a one minute incubation of counter hematoxylin (4). All of these steps work with each other in order to be able to view the overexpressed p 185 Her 2 under a microscope. When slides are finished in the IHC machine, they are removed and dipped into solutions of 95 % ethanol, 100 % ethanol, and Histo-Clear (clearing agent which leads to the production of high quality tissue slides), and are then cover slipped using Cytoseal XYL.

Once this is all done, the slides are then ready to be looked at and become officially scored.


Free research essays on topics related to: breast cancer, cancer cases, growth factor, ten minute, five minute

Research essay sample on Breast Cancer Ten Minute

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