The complexity of the mast cell is becoming more prominent. From being the cell recognized just to contribute to allergic inflammation it is now also associated with wound healing, protection against tumor growth and in recognition and defense against a wide range of pathogens. The location of the mast cell in the barrier between the external and internal environment of the body enables the cell to quickly respond to invading bacteria, virus and parasites. Diarrhea due to Escherichia coli infection, listeriosis, toxoplasmosis, Newcastle disease and bovine respiratory syncytial virus are examples of mast cell activating diseases that can affect animals in, as well as outside, the agricultural sector. Additionally, ticks and tick-borne diseases are of concern.

Complete tumour regression is the optimal outcome of cancer therapies. There are however types of tumours that naturally regress. Most of these are benign, dermatological and have an early onset in life. This literature study aims to elucidate the mechanisms behind spontaneous tumour regression. In Libechov Melanoblastoma-Bearing minipigs, an animal-model specifically bred to develop malignant melanoma, the tumours usually involute within three months.

Mast cells have for a long time been known to accumulate around tumors (Maltby et al., 2009). Studies show that they may be important and sometimes essential in tumor angiogenesis, tumor growth and metastasis of tumors (Soucek, et al., 2007; Xiang et al., 2010). In an expression array study (Wensman et al, submitted manuscript) performed on mouse mast cells exposed to tumor conditioned medium, the gene 4-1BB was among the most up-regulated genes compared to control medium. 4-1BB codes for a membrane receptor protein of the tumor necrosis factor superfamily and has been shown to be important in T cell regulation in tumor diseases. This study was performed to investigate if human mast cells up-regulate 4-1BB when they get exposed to tumor conditioned medium.

This literature study aims to examine the existence of cancer stem cells in breast cancer. The cancer stem cell theory states that there is a hierarchical organization within a tumour, in which a small subpopulation of the cells can initiate new tumours and maintain tumour growth whilst the bulk of the tumour cannot. These tumour initiating cells have shown to possess many characteristics similar to those of adult stem cells, which is why they are often referred to as cancer stem cells. Both cell types have the capacity of asymmetric division and have shown to possess mechanisms of resistance to both apoptosis and cancer drugs. The cancer stem cell theory elucidates many biological aspects such as the heterogeneity of tumours and the relapse of many cancers after what appeared to be successful treatments.

Tumour development occurs to a large extent because of dysregulation of the cell cycle. Of particular importance are defects occurring in the G1 phase. The reason why G1 is critical is because of the influence of several signals (external signals as well as cyclins and cdks) on this stage. The G1 phase can be divided into two parts, G1pm and G1ps. Each part has its ?own? restriction point which needs to be passed in order to progress to S phase.

Inflammatory airway disease (IAD) is a respiratory disorder that most commonly affects young horses performing at a high level. The clinical signs are often mild but the disorder can cause a marked decrease in performance to a point where the horse has to be taken of training and competing. The aetiology underlying IAD is not yet fully understood. One current theory is that a type I-hypersensitivity reaction due to allergens in the environment is the cause in some horses. The most reliable diagnostic method is a bronchoalveolar lavage (BAL) since it reflects the inflammatory status in the most distal parts of the lungs, which are affected in IAD.

Malt lymphoma is a malignant disease that can arise in a variety of extra nodal sites. Previous studies indicate that tumour arise from more mature B-cells.Our purpose was to examine the presence of clonality and somatic hypermutation of immunoglobulin (IgV?) of MALT lymphomas.Paraffin-embedded tumour samples from13 MALT lymphoma were subjected to rearrangement analysis, by using PCR, heteroduplex gels and sequence analysis.Successful amplification was seen in 10/13 cases and sequences of IgV? genes were obtained in 6/13, all of them were mutated. The percentage of mutation compared to germline sequences was 1,1% to 8,6% monoclonal rearrangemang. It was demonstrated that 5 of 7 clones were derived from the V?3 family, 2 from V?1 and 1 from the V? 4 family..

Determination of serum thymidine kinase 1 (TK-1) activity is used as a tumour marker in both human and veterinary medicine. TK-1 is an intracellular enzyme involved in a salvage pathway of DNA synthesis. The expression of TK-1 is cell cycle dependent and the activity increases markedly after the G1 to S transition in the cell cycle and then declines rapidly in G2. The pronounced proliferative activity in tumour cells result in a higher TK-1 enzyme activity within the cell. The fact that the increased TK-1 activity can be measured in serum makes TK-1 a useful marker in diagnostics of neoplastic diseases and it provides information regarding prognosis and treatment effectiveness. In human medicine a radioactive based test is used to determine the TK-1 serum activity.

Atopic dermatitis (AD) is a complex, often lifelong allergic disease affecting around 10 % of both dogs and humans. The hallmark symptom is severe pruritus, causing a lowered quality of life. Mast cells (MCs) are known to play an important part of the immunopathogenesis, promoting a faulty T helper cell type 2 (Th-2) response which follows by a production of specific immunoglobulin E (IgE) antibodies towards environmental allergens (Ag). To further investigate the role of MCs and its mediators in the progression of AD, a low-calcemic vitamin D3 analog (MC903) was used to induce AD-like symptoms locally on the ears of two different knock-out (KO) mouse strains. The first strain was Wsh-/- mice deficient in MCs.

Basal cell carcinoma (BCC) is the most common non-melanoma skin cancer. It can be divided in different subtypes. The most common type is superficial and is most frequently occurring on the trunk and on the face. In severe cases it can be difficult to differentiate basal cell carcinoma from other skin tumors, therefore a skin biopsy is conclusive diagnostic method. In terms of treatment, curettage is a common non-surgical treatment of basal cell carcinoma.

Pyometra, chronic purulent metritis in metoestrus, is a common disease in intact bitches. About 25% of all bitches in Sweden have contracted the disease before ten years of age. Clinical signs of the disease are varied, and the course may be either slow or acute. The diagnosis is most commonly made by radiographical or ultrasonographical examination of the abdomen in combination with blood biochemical and hematological analyses. The safest and most efficient treatment of pyometra is surgical ovariohysterectomy.There is room for improvement of both diagnostic tools and possible prognostic indicators for pyometra.Mast cells are large leucocytes, with granule that contain inflammatory mediators.

SAMMANFATTNINGDenna litteraturstudie har gjorts med syfte att utöka kunskapen om atopisk dermatit hos hund med fokus på mastcellens roll i immunopatogenesen. Atopisk dermatit är en relativt vanlig sjukdom som kan drabba alla hundar oavsett ras; den är oftast livslång och kräver visst arbete för att diagnosticera och behandla med gott resultat. Förutom att det är ett problem hos hundar, finns även ett nära samband med atopiska sjukdomar hos människa, och hundar fungerar som en bra modell för forskning på humansidan.Trots omfattande forskning, vet man fortfarande inte varför sjukdomen uppkommer. Många teorier finns kring den immunologiska bakgrunden, men stora delar är fortfarande okända. Att mastcellen spelar en nyckelroll är dock allmänt vedertaget.

The cell cycle is the time a cell spends between two cell divisions. The cell cycle includes several parallel processes, all of which must be completed before a cell is mature for dividing. In the first place, all subcomponents (RNA, protein and membrane lipids) need to double in quantity and this occurs continuously through the cell cycle. Furthermore, the genome and some chromosomal proteins must double and this take place during a limited interval in the middle of the cell cycle (S-phase). On either side of the S-phase are two "gaps" which is called G1 and G2. When the cell has passed a point in the G-phase they are irreversibly programmed to progress through the remaining of the cell cycle and will undergo the next cell division. When a cell have passed a point in the G1 phase, approximately four hours after mitosis, a normal cell is in a state of indecision.

The purpose of this study is to describe melanotic tumours and the pathogenesis of these tumours. The focus of this study is on differences between benign and malignant tumours as well as the prognosis one may expect when diagnosing this disease. The mechanisms responsible for the occurrences of the tumours are not yet fully understood. It is believed that factors such as chronic trauma, infections, medications and hormones affect the cell mechanisms in some way. Determinants of the malignancy of the tumour are not completely known.

Jönköping Small Animal Hospital is today the only clinic in Sweden to offer radiation therapy as a treatment of tumours. The body contains of billions of cells that all have to obey the regulations that are established. If a cell is exposed to a harmful substance, for example a chemical, it can be transformed into a tumourcell. Normally the body has a good defence but the tumourcell can survive and start to divide unrestrained. A tumour is starting to develop.