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Rapid intraoperative diagnosis. While patient still under anesthesia. Routine paraffin section takes minimum 2 days. Every type of staining can be done but H&E routine.

Rheumatoid factor is the autoantibody primarily associated with rheumatoid arthritis, indicating an autoimmune response.

The osmotic fragility test is the most relevant investigation for diagnosing hereditary spherocytosis, as it assesses the red blood cells' ability to withstand osmotic stress.

Long-acting beta-agonists (LABAs) can contribute to symptoms of increasing shortness of breath in patients with COPD.

Opsonins are molecules that enhance the phagocytosis of antigens by binding to their surfaces and acting as markers or labels that make them more recognizable to phagocytes.
1. lgG (Fc fragment): Immunoglobulin G (IgG) is the most common antibody isotype in human serum. It plays a crucial role in the secondary immune response. The Fc region of IgG is the fragment that interacts with Fc receptors present on the membrane of phagocytic cells. When an antigen is coated with IgG, the Fc fragments of these antibodies can bind to the Fc receptors, leading to the activation of the phagocytic process. This is known as antibody-dependent phagocytosis, where the antibody acts as an opsonin to facilitate the recognition and engulfment of the antigen by phagocytic cells.

2. C3b of complement cascade: The complement system is a cascade of proteins that can be activated in response to an infection or the presence of foreign substances. C3 is a central protein in this system, and when it is cleaved into C3a and C3b, the latter can bind directly to antigens. C3b acts as an opsonin by coating the surface of pathogens. The presence of C3b on a microbial surface allows it to be recognized by complement receptors on phagocytic cells, such as macrophages. This interaction enhances the efficiency of phagocytosis, as the receptors can recognize the bound C3b and engulf the antigen more readily.

3. IgM (Fc fragment) and C5b of complement cascade: While IgM is the first antibody isotype produced in response to an infection and can also opsonize antigens, it is less efficient than IgG due to its pentameric structure and lower affinity for phagocytic receptors. However, it is not as commonly associated with phagocytosis as IgG. Regarding C5b, it is part of the membrane attack complex (MAC) and is involved in the direct destruction of pathogens rather than acting as a classical opsonin that leads to phagocytosis. The MAC assembles on the surface of the antigen and creates pores, leading to osmotic lysis and destruction of the cell membrane.

Debulking the tumor by surgery makes the tumor cells re-enter the cell cycle and thus become susceptible to drug therapy: This statement is the most accurate. Surgical removal of a tumor (debulking) can indeed lead to the release of tumor cells into the circulation and may also alter the tumor microenvironment. This can make residual tumor cells more susceptible to chemotherapy, as they may re-enter the cell cycle and become more actively dividing, which is when many chemotherapy agents are most effective.