Cells die by one of two mechanisms – necrosis or apoptosis • Two physiologically different processes – Necrosis – death by injury – Apoptosis – death by suicide Appoptosis: Disintegration of cells into membrane-bound particles that are then eliminated by phagocytosis or by shedding.

Oncofoetal antigens are substances that are normally present in the developing fetus but are found in abnormally high quantities in the tissues of certain cancer cells. These antigens are proteins that can be used as markers for the detection of certain types of cancers. The presence of these antigens in cancer cells suggests that the tumor cells have partially reverted to a more primitive, embryonic stage of development.

Explanation for each option:

1. á-Fetoprotein (AFP): This is an oncofoetal antigen. It is a glycoprotein that is produced by the liver cells of the developing fetus. In adults, the production of AFP is usually very low. However, in cases of certain cancers such as hepatocellular carcinoma (primary liver cancer) and some types of testicular cancer, the tumor cells start producing AFP in large amounts. Therefore, high levels of AFP in the blood can be indicative of these cancers.

2. Carcinoembryonic antigen (CEA): CEA is another example of an oncofoetal antigen. It is a glycoprotein that is present in the gastrointestinal tract, pancreas, and sometimes in the respiratory and reproductive systems of a developing fetus. In adults, CEA levels are typically very low. However, in certain types of cancers, such as colorectal cancer, gastric cancer, and some forms of lung, pancreatic, and breast cancer, the tumor cells may start producing large amounts of CEA, which can be detected in the blood and used as a tumor marker for these malignancies.

3. A and B: Both α-fetoprotein and carcinoembryonic antigen are examples of oncofoetal antigens, so this option is correct.

Sarcoidosis is a systemic granulomatous disorder of unknown etiology that can affect any organ in the body. It is characterized by the formation of non-caseating granulomas, which are clumps of inflammatory cells that cluster together in response to an unidentified antigen. The lungs and lymph nodes are most commonly involved. Here's a detailed explanation for each of the options:

1. Dry cough: This is a common symptom of pulmonary sarcoidosis. The cough is usually persistent and non-productive, meaning it does not bring up mucus or phlegm. The presence of a dry cough is not contradicted in the statement "All are true regarding Sarcoidosis except," so this option is not the correct answer.

2. Exertional dyspnoea: Shortness of breath on exertion can occur in individuals with pulmonary sarcoidosis due to the inflammation and granuloma formation in the lungs. This symptom can be a result of the impaired lung function and decreased lung capacity caused by the disease. Therefore, this is also a true statement regarding sarcoidosis.

3. Wheezing: Wheezing is a high-pitched whistling sound that occurs during breathing, typically heard when airways become narrowed or blocked. It can be a symptom of pulmonary sarcoidosis, particularly if the disease involves the bronchi and bronchioles, leading to bronchial obstruction and airflow limitation. However, it is not the primary symptom and may be less common than the other respiratory symptoms mentioned.

4. Hemoptysis: While hemoptysis, or coughing up blood, is not a hallmark symptom of sarcoidosis, it can occur in some cases, particularly when the granulomas are located in the lungs. It is usually mild and self-limited, but severe cases can lead to significant bleeding. This is a true statement regarding sarcoidosis, as it is a possible, although less common, respiratory symptom of the disease.

Since all the options (1, 2, and 4) are true regarding Sarcoidosis

Enlargement of interendothelial junctions: This option refers to the widening of the spaces between endothelial cells, which can occur during inflammation. This enlargement allows leukocytes to pass through the endothelium more easily. This is a significant mechanism in the process of leukocyte transmigration.

Leptospirosis, Malaria, Viral Hepatitis A can produce febrile jaundice