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Objective: The aim of the study was to evaluate the role of vitamin B₁₂ in patients with pernicious anemia. Materials and Methods: This study was conducted prospectively at the Turgut Özal Medical Center, Department of Hematology, between April and November 2002. Absolute numbers and ratio of the surface antigens of T and B lymphocyte subgroups, CD4/CD8 ratio were calculated in order to evaluate changes in leukocyte and lymphocyte numbers; natural killer (NK) cell count, serum C3, C4, and levels of immunoglobulins G, A, and M were also measured to evaluate vitamin B₁₂ effect on immunity. Values obtained before treatment with cyanocobalamin were compared with those found during peak reticulocyte count. Results: In vitamin B₁₂-deficient patients, absolute numbers of CD4+ and especially CD8+ lymphocytes were found to be decreased; CD4/CD8 ratio increased, and NK cell activity was depressed. After cyanocobalamin treatment, absolute numbers and percentage of lymphocyte subgroups were elevated. Increased CD4/CD8 ratio and depressed NK cell activity were restored and levels of C3, C4, and immunoglobulins were elevated. Conclusion: These findings suggest that vitamin B₁₂ has important immunomodulatory effects on cellular immunity, and abnormalities in the immune system in pernicious anemia are restored by vitamin B₁₂ replacement therapy.

Objective: To report a case of arteriovenous fistula (AVF) following bone marrow aspiration and trephine biopsy. Clinical Presentation and Intervention: A 76-year-old man was diagnosed with acute myeloblastic leukemia. Pain and hematoma were detected in his left leg and hip 4 days after bone marrow aspiration and trephine biopsy. A pelvic arteriography was performed, and a diagnosis of AVF was made. Conclusion: This case shows that clinicians should be aware of AVF, especially in cases with refractory bleeding after bone marrow aspiration and trephine biopsy despite normal blood coagulation parameters.

Vincristine, adriamycin, and dexamethasone (VAD) chemotherapy protocol is first-choice treatment in newly diagnosed multiple myeloma patients in many centers. Sudden hearing loss associated with vincristine therapy is a rarely observed event in the VAD protocol. We describe a 69-year old male patient diagnosed with multiple myeloma 7 months ago who developed sudden bilateral hearing loss related to vincristine therapy. This uncommon adverse effect of vincristine is discussed and the literature reviewed.

Vincristine sulfate is a chemotherapeutic agent used in different cancer therapies. It is also the first choice of treatment for peripheral T-cell lymphoma with cyclophosphamide and adriamycin. Sudden hearing loss during vincristine therapy is a very rare event. This is a case of a 16-year old girl who developed sudden bilateral hearing loss related to vincristine therapy.