Bax interacts with the permeability transition pore to induce permeability transition and cytochrome c release in isolated mitochondria

Cytochrome c release and the mitochondrial permeability transition (PT), including loss of the transmembrane potential (Δψ), play an important role in apoptosis. Using isolated mitochondria, we found that recombinant Bax and Bak, proapoptotic members of the Bcl-2 family, induced mitochondrial Δψ loss, swelling, and cytochrome c release. All of these changes were dependent on Ca²⁺ and were prevented by cyclosporin A (CsA) and bongkrekic acid, both of which close the PT pores (megachannels), indicating that Bax- and Bak-induced mitochondrial changes were mediated through the opening of these pores. Bax-induced mitochondrial changes were inhibited by recombinant Bcl-x_L and transgene-derived Bcl-2, antiapoptotic members of the Bcl-2 family, as well as by oligomycin, suggesting a possible regulatory effect of F₀F₁-ATPase on Bax-induced mitochondrial changes. Proapoptotic Bax- and Bak-BH3 (Bcl-2 homology) peptides, but not a mutant BH3 peptide nor a mutant Bak lacking BH3, induced the mitochondrial changes, indicating an essential role of the BH3 region. A coimmunoprecipitation study revealed that Bax and Bak interacted with the voltage-dependent anion channel, which is a component of PT pores. Taken together, these findings suggest that proapoptotic Bcl-2 family proteins, including Bax and Bak, induce the mitochondrial PT and cytochrome c release by interacting with the PT pores.     

A hairy B cell lymphoproliferative disorder resembling hairy cell leukemia

This case report describes a hairy B cell lymphoproliferative disorder (HBLD) with clinical and hematological features resembling hairy cell leukemia. The patient was a 29-year-old female who demonstrated atypical lymphocytes in her peripheral blood. Physical examination demonstrated splenomegaly, but there were no palpable superficial lymph nodes. Hematological examination showed a leukocyte count of 10.6 x 10(3)/mm3 with 41% atypical lymphocytes. Bone marrow examination showed a normal cellular and an atypical lymphocyte count of 42%. The atypical lymphocytes had microvilli and prominent membranous ruffles on their surfaces. Atypical lymphocytes expressed CD5- CD10- CD11c+ CD19+ CD20+ CD23- CD25- on the surface of the cells on examination by with a fluorescence activated cell sorter. Although these findings were similar to hairy cell leukemia, Japanese variant, the surface marker of the kappa chain and lambda chain was unbiased and studies of immunoglobulin gene rearrangements and expression showed polyclonal proliferation of B cells. Therefore, we diagnosed this patient as having HBLD. Because she did not demonstrate anemia or thrombocytopenia, she is not currently receiving medication. To date, the atypical lymphocyte count has not changed.     

Effects of local administrations of tempol and diethyldithio-carbamic on peripheral nerve activity

We have recently shown that systemic administration of a superoxide dismutase mimetic, tempol, resulted in decreases in mean arterial pressure and heart rate along with a reduction in renal sympathetic nerve activity (RSNA). It has also been shown that these parameters are significantly increased by systemic administration of a superoxide dismutase inhibitor, diethyldithio-carbamic (DETC), indicating a potential role of reactive oxygen species in the regulation of RSNA. In this study, we examined the effects of local administrations of 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (tempol) and DETC on RSNA in anesthetized rats. Either tempol or DETC was directly administered onto the renal sympathetic nerves located between the electrode and ganglion. Local application of tempol (10 microL, 0.17 to 1.7 mol/L, n=6) resulted in dose-dependent decreases in integrated RSNA (by -81+/-6% at 1.7 mol/L) without alterations in mean arterial pressure and heart rate. In contrast, DETC (10 microL, 0.17 to 1.7 mol/L, n=6) increased RSNA dose-dependently. The responses of RSNA to tempol and DETC were significantly greater in spontaneously hypertensive rats than in normotensive rats (n=6, respectively). Local application of sodium nitroprusside (1 mmol/L) or N(G)-nitro-L-arginine methyl ester (0.11 mol/L) altered neither basal RSNA nor tempol-induced reductions in RSNA (n=6 and 5, respectively). A voltage-gated potassium channel blocker, 4-aminopyridine (0.1 mol/L), significantly decreased basal RSNA (by -81+/-1%) and completely prevented DETC-induced increases in RSNA (n=5). These results suggest that reactive oxygen species play a role in the regulation of peripheral sympathetic nerve activity, and that at least part of this mechanism is mediated through voltage-gated potassium channels.     

Terminal-Restriction Fragment Length Polymorphism (T-RFLP) Analysis for Changes in the Gut Microbiota Profiles of Indomethacin- and Rebamipide-Treated Mice

Background/Aims: We investigated the effects of indomethacin and rebamipide on the gut microbiota profiles using terminal restriction fragment polymorphism (T-RFLP) analysis. Materials and Methods: Female C57BL/6J mice were given indomethacin (10 mg/kg, s.c.) once a day and 2.5 mg rebamipide orally 3 times a day. After 7 days, they were sacrificed, and luminal contents were obtained from the ileum and cecum. The gut microbiota communities were analyzed by T-RFLP analysis with BslI digestion. Results: T-RFLP analyses showed that rebamipide and indomethacin had no significant effects on the gut microbiota profiles in the ileum and cecum. In contrast, the combination of rebamipide + indomethacin induced a significant change in the gut microbiota. The changes in the microbiota composition induced by the combination of rebamipide + indomethacin were characterized by the increase in the orders Bifidobacteriales and Lactobacillales, the genera Bacteroides and Prevotella and the family Clostridiaceae. The diversity of the gut microbiota community generated by the combination of rebamipide + indomethacin was significantly higher than those induced by either rebamipide or indomethacin alone. Conclusion: The combination of rebamipide + indomethacin induces remarkable changes in the gut microbiota composition and diversity. The clinical activity of rebamipide on nonsteroidal anti-inflammatory drug-induced intestinal injury may be exerted through a modulation of the gut microbiota.     

Development of follicular lymphoma of the cervical lymph nodes in a postoperative patient with tongue cancer

Patients with head and neck squamous cell carcinoma are at an increased risk of developing second malignancies. Most commonly, these second primary malignancies are squamous cell carcinoma of the head and neck region, but also noted are esophageal cancer or lung cancer. Hematologic malignancies are uncommon second malignancies. Diagnosis can be challenging, particularly when a patient suffers metastases of squamous cell carcinoma to the cervical lymph nodes in addition to synchronous or metachronous malignant lymphoma that originates in the cervical lymph nodes. This article describes a case of primary follicular lymphoma in the cervical region that was discovered during a postoperative follow-up after partial glossectomy and neck dissection for tongue cancer.