Intramolecular Hiyama Coupling: Synthesis of 1,8,13-Trisubstituted Chiral Triptycenes with Three Different Substituents by Intramolecular Substituent Transfer.

Herein, we describe Hiyama coupling via intramolecular substituent transfer from silicon on one blade of triptycenes to another to yield 1,8,13-trisubstituted chiral triptycenes. This reaction is attributed to the proximity effect of substituents on triptycene, which plays an important role in not only the formation of the oxy-palladacycle but also the activation of the silyl group to facilitate σ-bond metathesis. After bromination and nucleophilic ring opening, the second intramolecular Hiyama coupling provided various 1,8,13-trisubstituted chiral triptycenes. The optical resolution of 1,8,13-triptycene afforded an optically active form for the first time.

Quadruple Role of Pd Catalyst in Domino Reaction Involving Aryl to Alkyl 1,5-Pd Migration to Access 1,9-Bridged Triptycenes.

A Pd-catalyzed domino reaction of 1,8,13-tribromo-9-methoxytriptycenes is reported. Under conventional Suzuki coupling conditions, the triptycenes underwent multiple transformations to give 1,9-bridged triptycenes. Based on mechanistic investigations, a single Pd catalyst functions as Pd0 , PdII and PdIV species to catalyze four distinct processes: (1) aryl to alkyl 1,5-Pd migration, (2) intramolecular arylation, (3) homocoupling of phenylboronic acid and (4) Suzuki coupling. DFT calculations revealed that 1,5-Pd migration likely proceeds via both concerted PdII and stepwise PdIV routes. Asymmetric synthesis of the chiral triptycenes, as well as optical resolution, and further transformation are also reported.

Hepatic contribution to a marked increase in the plasma concentration of baicalin after oral administration of its aglycone, baicalein, in multidrug resistance-associated protein 2-deficient rat.

Baicalin (BG) and its aglycone, baicalein (B), are strong antioxidants and have various pharmacological actions and show unique metabolic fates in the rat. The aim of the present study was to evaluate the contribution of multidrug resistance-associated protein 2 (Mrp2, Abcc2) to the disposition of BG after oral administration of B using the Eisai hyperbilirubinemic rat (EHBR, Mrp2-deficient), in comparison with the Sprague-Dawley rat (SD, the wild-type form of EHBR). When B at a dose of 12.1 mg/kg was administered orally to EHBRs, the area under the concentration curve from time 0 to 24 h (AUC(0-24 h)) and C(max) values of plasma BG, 27.6 + or - 3.5 microM x h and 11.4 + or - 3.9 microM, respectively, were significantly higher at 5-fold and 8-fold, respectively, than those (AUC(0-24 h) value of 5.39 + or - 1.37 microM x h and C(max) value of 1.51 + or - 0.38 microM) in SD rats. In addition, when B at a dose of 1.2 mg/kg was injected into the portal vein of EHBRs, a marked reduction in the biliary excretion of BG (6.59 + or - 5.64 nmol) and a marked increase of BG in the systemic circulation (AUC(0-120 min) of 75.4 + or - 34.5 microM x min) were observed, in comparison with those (biliary excretion of 29.7 + or - 9.3 nmol and AUC(0-120 min) value of 2.42 + or - 1.44 microM x min) in SD rats. Thus, it was clarified that after oral administration of B, the markedly higher concentration of plasma BG in EHBRs than in SD rats was caused mainly by a drastic reduction in the biliary excretion of BG and marked enhancement of its sinusoidal efflux from the liver.

Efflux of baicalin, a flavone glucuronide of Scutellariae Radix, on Caco-2 cells through multidrug resistance-associated protein 2.

Baicalin and its aglycone, baicalein, being are strong antioxidants and have various pharmacological actions. Baicalein has shown a unique metabolic fate in rat intestine, being excreted into the intestinal lumen from mucosal (epithelial) cells following glucuronidation of baicalein absorbed after oral administration. The purpose of this study was to examine the absorption and excretion of baicalin and baicalein in a Caco-2 cell monolayer model to evaluate the disposition of baicalin and baicalein in the human intestine. When baicalein at 5 microM was loaded on the apical side of the Caco-2 cell monolayer, baicalein was not transferred to the basolateral side, but more baicalin was excreted onto the apical side than was being absorbed onto the basolateral side. The amount of baicalin recovered on both sides accounted for more than 90% of the baicalein absorbed from the apical surface. This was supported by the fact that Caco-2 cell microsomes showed UDP-glucuronate glucuronosyltransferase activity towards baicalein to form baicalin. On the other hand, when baicalein was loaded at higher concentrations, baicalin excretion became saturated, and then baicalein was transferred to the basolateral side. Furthermore, baicalin efflux was not inhibited by MDR1/P-glycoprotein substrates such as ciclosporin and vinblastine, but significantly inhibited by multidrug resistance-associated protein 2 (MRP2, ABCC2) substrates such as probenecid and genistein. MRP2 was also detected in Caco-2 cells by Western blotting using specific antibodies. In addition, baicalin, but not baicalein, enhanced dose-dependently the vanadate-sensitive ATPase activity of human MRP2. These results indicated that, in Caco-2 cells, any baicalein absorbed after loading at low concentrations of baicalein was not transferred to the basolateral side, but was first transformed into baicalin in the cells and excreted through the action of MRP2, mainly to the apical side.

Colonic lipoma with florid vascular proliferation and nodule-aggregating appearance related to repeated intussusception.

A unique case of repeatedly intussuscepted colonic lipoma mimicking an epithelial tumor in a 50-year-old man is reported. The tumor was located in the ascending colon and was approximately 5 cm in diameter. Colonoscopic and barium-enema examinations suggested a huge epithelial tumor because of its nodule-aggregating appearance. In contrast, computed tomography examination showed a fatty element in the core of the lesion. The biopsy specimens suggested a primary angiomatous lesion because of its pronounced vascular proliferation. Because the presumed diagnoses based on the examinations were different, the preoperative diagnosis was not confirmed. The tumor was composed of intramural lipoma with a multiple polypoid mucosa overlay. This lesion was unique in that the lipoma appeared to be within the muscularis propria and the multiple polypoid appearance of its covering mucosa. The mucosal changes including florid vascular proliferation, fibromuscular obliteration and epithelial regeneration suggested a reparative process, with ischemic damage due to the effects of intussusception being the most likely event. It should be kept in mind that even a simple lipoma can have a unique appearance reminiscent of epithelial tumor when it repeatedly experiences intussusception.

Enteric excretion of baicalein, a flavone of Scutellariae Radix, via glucuronidation in rat: involvement of multidrug resistance-associated protein 2.

PURPOSE: Baicalin (BG) and its aglycone, baicalein (B), are strong antioxidants and have various pharmacological actions. The purpose of this study was to evaluate efflux of BG from rat intestinal mucosal cell following glucuronidation of B absorbed after oral administration of B. METHODS: The absorption and excretion of BG and B were evaluated in rats using the in situ jejunal loop technique and in vitro jejunal everted sac experiments. BG and B levels were determined by high-performance liquid chromatography with electro-chemical detection to ensure selectivity and high sensitivity. RESULTS: A large amount (30.4% recovery) of BG, but no B, was detected in the intestinal lumens of germ-free rats 4 h after oral administration of B (12.1 mg/kg), in comparison with a substantial recovery (55.1%) of unabsorbed BG 4 h after its administration. During the in situ rat jejunal loop absorption experiment, B disappeared rapidly, and 8% of the lost B was excreted into the loop as BG 20 min after infusing 0.1 mM B. In an in vitro absorption experiment using everted rat jejunal sac, BG also appeared outside the sac, accompanied by the disappearance of B from the outer (mucosal) side. However, very little of B was transferred to the inner (serosal) side of the sac, and only a trace of BG was detected inside the sac. Thus, in both the loop and the everted sac systems, the efflux of BG from the mucosal surface was saturated with the concentration of B added. Moreover, the efflux rate of BG in the everted jejunal sac from Eisai hyperbilirubinemic rat (EHBR) was significantly lower by 56.4% than that from Sprague-Dawley rat. CONCLUSIONS: These results indicate that, in rat, a large proportion of any B absorbed is retained, transformed into BG within the intestinal mucosal cells, and coordinately excreted through multidrug resistance-associated protein 2 (MRP2) into the intestinal lumen.

Acute tumor lysis syndrome caused by palliative radiotherapy in patients with diffuse large B-cell lymphoma.

Acute tumor lysis syndrome (TLS) is a condition that results from the rapid destruction of tumor cells accompanied with a massive release of cellular breakdown products. Acute renal failure resulting from TLS has been reported in cases of hematologic malignancies, spontaneous or treatment induced, the latter especially by chemotherapy. We present the case of a patient with diffuse large B-cell lymphoma who developed radiotherapy-induced TLS and subsequently acute renal failure. He presented with a large mediastinal tumor compressing the airway, thus causing dyspnea. After 6 Gy/3 fractions/3 days of palliative radiotherapy for the tumor, a decrease in urine volume was noted as well as rapid tumor shrinking. Because this patient died despite previous prophylaxic anti-uric acid treatment and hemodialysis, his case illustrates the need to anticipate the development of acute renal failure, even though there may be no remarkable serum uric acid elevation after the initiation of radiotherapy.

Heavily melanotic perivascular epithelioid clear cell tumor of the kidney.

A black-colored and well-circumscribed renal tumor in a 71-year-old woman is reported. The tumor was unique in that it was rich in vasculature and exclusively composed of perivascular epithelioid clear cells. Morphological features were reminiscent of conventional renal cell carcinoma (RCC). However, immunohistochemical examinations showed that the tumor cells did not express any epithelial markers, but diffusely and intensely expressed a melanocytic marker, gp-100/HMB-45. Another striking feature of the tumor was a large amount of cytoplasmic pigment that made the tumor wholly black. The pigment was not stained with Berlin-blue, completely bleached with potassium permanganate, and stained with Fontana-Masson staining, which suggests that the pigment was melanin. Morphological features and immunohistochemical findings indicated that the present tumor was an extreme example of a perivascular epithelioid clear cell tumor with a large amount of melanin, which has not been previously reported. One should be aware of the pure form of perivascular epithelioid clear cell tumor of the kidney because it is sometimes very difficult to differentiate this tumor from conventional RCC. Immunohistochemical examinations and the presence of cytoplasmic melanin can help the differentiation.

Four cases of central nervous system involvement of breast malignant lymphoma.

Although malignant lymphoma of the breast is a rare disease, we recently experienced a high incidence of central nervous system (CNS) involvement. Thus, we retrospectively reviewed clinical records of 921 patients with breast tumors, treated from 1990 to 2002, to examine CNS involvement. Eight patients were found to have malignant lymphomas during this period. Of these, four patients ranging from 46 to 80 years of age had CNS involvement, one with Burkitt type and three with diffuse large B-cell lymphoma. The patients received surgery and/or chemotherapy and/or radiotherapy. The four other patients without CNS involvement are alive without tumor, whereas three of four patients with CNS involvement died of the disease. It should be noted that CNS involvement in breast lymphoma is not so rare. It is difficult, but important, to determine whether malignant lymphoma of the breast originates in the breast or is of systemic origin. Although brain metastasis could be treated effectively by radiotherapy and/or chemotherapy, the prognosis was poor. Further intensive treatment is required for breast malignant lymphoma with CNS involvement.

Lipomatous apocrine mixed tumor of the skin.

The common mesenchymal elements of apocrine mixed tumor of the skin are mucin and chondroid tissue. An apocrine mixed tumor of the skin with extensive adipose content is reported. A 56-year-old Japanese man presented with a subcutaneous mass in the glabella region that was 1 cm in diameter and had developed within the preceding 5 years. Light microscopic examination showed a well-circumscribed and encapsulated subcutaneous tumor composed of tubular structures with apocrine secretion and mucin as well as extensive adipose tissue. This case, in light of another recently reported case, indicates that adipose tissue can be the major mesenchymal element in apocrine mixed tumor of the skin.