ABSTRACT
Acute myeloid leukemia (AML) is the most prevalent form of leukemia in adults, with rising global incidence rates. AML usually presents with non-specific clinical features such as pallor, fever, and bleeding. This case report discusses a unique presentation of AML, where a 25-year-old female with a history of hypertension presented with unilateral facial swelling, chest pain, and shortness of breath. Radiologic investigations revealed a mediastinal mass encasing the superior vena cava (SVC), confirming the suspicion of SVC syndrome. Upon testing with a biopsy, the mass was found to be composed of immature myeloid cells confirming the diagnosis of myeloid sarcoma-associated AML. The patient's treatment involved a combination of surgical debridement, induction chemotherapy, supportive care, and management of complications. This case highlights that despite its common occurrence, AML may present with atypical clinical manifestations such as SVC syndrome, posing challenges in its diagnosis and timely management.
ABSTRACT
Deep venous thrombosis (DVT) commonly affects the lower extremities, often as a result of prolonged immobilization. However, upper limb DVT is an atypical presentation, typically associated with risk factors such as the use of a peripherally inserted central catheter (PICC) line. This case report describes an uncommon case of DVT management in a patient with Crohn's disease, a condition more frequently characterized by painful lower gastrointestinal symptoms and chronic diarrhea. A 22-year-old male with a history of Crohn's disease developed swelling and purplish discoloration at the brachial site of a PICC line site. Laboratory results indicated anemia with a hemoglobin level of 9.9 g/dL and a hematocrit of 31.9%. Doppler ultrasound confirmed the DVT in the left long axillary, left subclavian, and left long basilic veins. Given the patient's concurrent lower gastrointestinal bleeding, a cautious approach was required to balance the risks and benefits of anticoagulation. Upon recommendation by Hematology, a prophylactic dose of enoxaparin was initiated and subsequently escalated to a therapeutic dose as tolerated. The patient's condition was closely monitored, and he successfully reached the full therapeutic regimen without complications. This case underscores the importance of individualized DVT treatment strategies in the context of concurrent Crohn's disease, offering insights into managing anticoagulation in the presence of bleeding risks.
ABSTRACT
We have prepared a site-specific mutant of human carbonic anhydrase (HCA) II with histidine residues at positions 7 and 64 in the active site cavity. Using a different isozyme, we have placed histidine residues in HCA III at positions 64 and 67 and in another mutant at positions 64 and 7. Each of these histidine residues can act as a proton transfer group in catalysis when it is the only nonliganding histidine in the active site cavity, except His(7) in HCA III. Using an (18)O exchange method to measure rate constants for intramolecular proton transfer, we have found that inserting two histidine residues into the active site cavity of either isozyme II or III of carbonic anhydrase results in rates of proton transfer to the zinc-bound hydroxide that are antagonistic or suppressive with respect to the corresponding single mutants. The crystal structure of Y7H HCA II, which contains both His(7) and His(64) within the active site cavity, shows the conformation of the side chain of His(64) moved from its position in the wild type and hydrogen-bonded through an intervening water molecule with the side chain of His(7). This suggests a cause of decreased proton transfer in catalysis.
