Propofol increases the rate of albumin-unbound free midazolam in serum albumin solution.

Propofol and midazolam have a synergistic anesthetic action. One of the reasons for this is thought to be the inhibitory effect of propofol on midazolam metabolism. However, because both drugs bind strongly to serum protein, their interaction may not only involve the effects of propofol on midazolam metabolism, but may also involve propofol's effects on serum protein-binding. Against this background, we investigated the characteristics of midazolam binding to serum albumin, and evaluated the effects of both propofol and ketamine on this binding. Midazolam was added to a serum albumin solution with propofol or ketamine, and, after incubation for 1 h, albumin-free solution was separated from the sample and the midazolam concentration was measured using a high-performance liquid chromatography system. The albumin-unbound rate of midazolam was evaluated and compared with the rate in the control solution (only midazolam). Propofol significantly raised the rate of albumin-unbound free midazolam, while ketamine had no effect on the binding of midazolam to serum albumin. These findings suggest that the increase in albumin-unbound free midazolam brought about by propofol is involved in the synergistic effect of these two agents.

[Case of von Hippel-Lindau disease diagnosed by detection of multiple pancreatic endocrine tumors and renal tumor 13 years after bilateral adrenalectomy].

von Hippel-Lindau (VHL) syndrome is an inherited neoplastic syndrome caused by abnormity of the VHL gene found on the short arm of the chromosome 3. We reported a case of VHL disease diagnosed by the detection of multiple pancreatic endocrine tumors and renal tumor 13 years after bilateral adrenalectomy. A 40-year-old man presented with multiple pancreas tumors (maximum size 42 mm in diameter) detected by screening abdominal ultrasonography. A 23 mm renal tumor was detected by contrast computed tomography scan at that time. His past history included left retinal angioma (age 15) and bilateral adrenal pheochromocytoma (age 27). VHL was diagnosed by genetic testing. Endoscopic ultrasound-guided fine-needle aspiration biopsy of the pancreas tumor was performed, and tumor was diagnosed as an endocrine tumor. After diagnosis, distal pancreatectomy (body-tail) was performed. This was a didactic case indicating that we should suspect VHL syndrome based on past history and family history and follow such cases up strictly.

[A case of duodenal gangliocytic paraganglioma with lymph node metastasis].

A 28-year-old man complained of tarry stool. A series of examinations showed a submucosal tumor with bleeding at the papilla of Vater and a swollen # 17b lymph node, both of which indicated a hypervascular tumor. The pathological findings of the enucleated tumor specimens revealed gangliocytic paraganglioma with metastasis to the # 17b lymph node. Additional pancreaticoduodenectomy revealed another # 17b lymph node metastasis 7-mm in diameter. Although the majority of gangliocytic paragangliomas are benign, 7% of reported cases have lymph node metastases, as shown in the present case. These findings are important in treating patients with gangliocytic paraganglioma.