Inhibitory effects of metals on ATP-induced current through P2X7 receptor in NG108-15 cells

We investigated the effects of heavy metal ions on the ATP-induced nonselective cation current through P2X7 receptor (I(NS x P2X7)) in NG108-15 cells using the whole-cell patch-clamp technique. Cu2+ inhibited the I(NS x P2X7) most potently among the metal ions investigated. Other metals such as Ni2+, Cd2+, Zn2+ and Co2+ also inhibited the I(NS x P2X7) in concentration-dependent manners. The order of potency was Cu2+ > Ni2+ > Cd2+ > Zn2+ > Co2+ with IC50 values of 16 nM, 0.79 microM, 1.2 microM, 3.0 microM and 4.6 microM, respectively. Fe3+ (10 and 100 microM) and Mn2+ (10 microM) did not affect the INS P2X7. A high concentration of Mn2+ (100 microM) slightly inhibited the I(NS x P2X7). When the concentration-response curve of ATP was obtained in the presence of 3 and 10 nM Cu2+, the maximal response but not the EC50 value appeared to be reduced, suggesting that the inhibition is not competitive. These results suggest that under physiological and toxicological conditions, metal ions, such as Cu2+, Ni2+, Cd2+, Zn2+ and Co2+, may modulate P2X7 receptor channels as inhibitors.     

Effects of anions on ATP-induced [Ca2+], increase in NG108-15 cells

We investigated the effects of anions on different P2 receptors by measuring ATP-induced increase in intracellular Ca2+ concentration ([Ca2+]i) in fura-2-loaded NG108-15 and PC12 cells. In NG108-15 cells, ATP at 100 microM and 1 mM induced a transient and a sustained [Ca2+]i increase, respectively. The former, but not the latter, was inhibited by U-73122, indicating that the former was via the P2Y2 receptor and the latter via the P2X7 receptor. When external Cl- was replaced by other anions, the [Ca2+]i increase mediated by the P2Y2 receptor was not changed, but that mediated by the P2X7 receptor varied in the order of aspartate- > methanesulfonate > Cl- > Br > or = I-. In PC12 cells, transient [Ca2+]i increases mediated by the P2Y2 and P2X2 receptors were not affected by various anions. These results suggest that modulation by anions is unique to the P2X7 receptor and does not occur in P2Y2 and P2X2 receptors. This may be because the mechanism of ATP binding to the P2X7 receptor may be different than that to other P2 receptors.     

Differential effects of bupivacaine enantiomers,ropivacaine and lidocaine on up-regulation of cell surface voltage-dependent sodium channels in adrenal chromaffin cells

In cultured bovine adrenal chromaffin cells, (+/-)-bupivacaine inhibited veratridine-induced 22Na(+) influx (IC(50) 6.8 microM). The IC(50) of (+)-bupivacaine (2.8 microM) was 6.2-, 7.4-, and 17.1-fold lower than those of (-)-bupivacaine (17.3 microM), (-)-ropivacaine (20.6 microM), and lidocaine (47.8 microM). Chronic (i.e. 3-h) treatment of cells with (+/-)-bupivacaine increased cell surface [3H]saxitoxin ([3H]STX) binding capacity by 48% (EC(50) of 233 microM; t(1/2)=7.4 h), without changing the K(d) value. Treatment for 24 h with either (+)- or (-)-bupivacaine, or (-)-ropivacaine elevated [3H]STX binding, whereas 24-h treatment with lidocaine had no effect. The rise of [3H]STX binding by (+/-)-bupivacaine was prevented by cycloheximide, an inhibitor of protein synthesis, or brefeldin A, an inhibitor of cell surface vesicular exit from the trans-Golgi network; however, (+/-)-bupivacaine did not increase Na(+) channel alpha- and beta(1)-subunit mRNA levels. In cells subjected to (+/-)-bupivacaine treatment (1 mM for 24 h) followed by 3-h washout, veratridine-induced 22Na(+) influx was enhanced, even when measured in the presence of ouabain, an inhibitor of Na(+),K(+)-ATPase. Ptychodiscus brevis toxin-3 potentiated veratridine-induced 22Na(+) influx by 2.3-fold in the (+/-)-bupivacaine-treated cells, as in non-treated cells. These results suggest that lipophilic bupivacaine enantiomers or (-)-ropivacaine acutely inhibit Na(+) channel gating, whereas its chronic treatment up-regulates cell surface expression of Na(+) channels via translational and externalization events.     

Hepatocyte growth factor protects functional and histological disorders of HgCl(2)-induced acute renal failure mice

Hepatocyte growth factor (HGF) enhances proliferation of renal epithelial cells as well as hepatocytes. HGF accelerates recovery from acute renal failure (ARF) in animal models. However, pharmacological profiles of HGF including its action mechanism has not been studied in detail. An HgCl(2)-induced ARF mouse was used in this study to evaluate the efficacy of HGF. Single administrations of recombinant human HGF or vehicle were given to ARF mice 30 min after HgCl(2) injection. Renal function was monitored by measuring serum creatinine, blood urea nitrogen and creatinine clearance. In the ARF mice, there was a deterioration of renal function biochemical parameters and histological evidence of renal damage including acute tubular necrosis of proximal tubules. These were both significantly ameliorated by a single HGF administration. The effect of HGF was noticeable in the early phase of ARF (1 day after onset) when there was no histological evidence of increased labeling indexes in renal tubular epithelial cells. Western blot analysis of the c-Met/HGF receptor showed that tyrosine phosphorylation was enhanced immediately after HGF administration indicating direct activation of renal epithelial cells. HGF prevented increase of apoptotic nuclei with DNA fragmentation in renal epithelial cells which suggests cytoprotective activity of HGF on renal epithelial cells in the ARF mice.     

Recent advances in the regulation of matrix metalloproteinase 2 activation: from basic research to clinical implication (Review)

Matrix metalloproteinases (MMPs) play an important role in degradation of extracellular matrix (ECM), which is an essential step in the cascade of metastasis. Various types of MMPs are expressed and activated in head and neck squamous cell carcinoma (HNSCC) as well as other human cancers. MMP-2 is a prominent predictor of poor prognosis. Membrane type 1-MMP (MT1-MMP) was originally identified as an activator of MMP-2. In addition to the original role, recent studies show other important functions of MT1-MMP such as degradation of type I collagen and cleavage of CD44. Tissue inhibitor of MMP-2 (TIMP-2) was identified as an inhibitor of MMP-2 and MT1-MMP. However, TIMP-2 was reported to be essential for cell-mediated activation of MMP-2, and thus the contribution of TIMP-2 to tumor invasion has remained controversial. Some studies also suggested a role of TIMP-2 as a predictor of poor prognosis. Thus, inhibition of MMP activation by TIMPs is not a suitable strategy for suppressing invasion and metastasis. Instead of TIMP-2, various MMP inhibitors (MMPI) such as BB-2516 have been investigated with regard to suppression of tumor progression and improvement of prognosis in patients with advanced cancers, which resulted in no clinical efficacy. MMPs are especially important in the early stage of cancer progression, and thus strategies for future MMPI trials should be reconsidered.     

Complete response in an elderly patient with advanced gastric scirrhous cancer treated with combined chemotherapy of TS-1 and CDDP

A 79-year-old male was diagnosed as having a scirrhous cancer of the stomach. Carcinomatous peritonitis was suspected on abdominal CT examination and the CA19-9 showed a high level of 95 U/ml. The patient was treated with combined chemotherapy of TS-1 and CDDP. TS-1 (100 mg/day) was administered for 14 days followed by 14 days rest as one course. CDDP was administered in 24-h continuous intravenous infusion on day 8. This treatment was done every 4 weeks regularly. After 5 courses, X-ray and endoscopy examinations revealed disappearance of cancerous lesions in the stomach with an improvement in the extensibility. No cancer cell were confirmed by endoscopic biopsy, nor did a CT-scan detect carcinomatous peritonitis. The CA19-9 decreased within the normal limit. Ten months after chemotherapy was started, the patient was very healthy without a recurrence of cancer. This combined chemotherapy has administered in 8 courses, and during this period no high grade toxicities (WHO grade 3 or 4) occurred. This TS-1/CDDP chemotherapy was effective for scirrhous gastric cancer and might be administered safely even for aged patients.     

Retrodental synovial cyst which disappeared after posterior C1-C2 fusion: A case report

Synovial cysts of the cervical spine are extremely rare. We describe an 8-year-old boy with atlantoaxial subluxation and hypoplasia of the dens. Magnetic resonance imaging showed a round lesion, posterior to the odontoid process. This mass was characterized by a low signal intensity on T1-weighted images, and high signal intensity on T2-weighted images. The retrodental synovial cyst disappeared after posterior atlantoaxial arthrodesis.     

Malignant gastrointestinal stromal tumor of the small intestine complicated with pulmonary tuberculosis during treatment with imatinib mesylate

We describe a patient who had a metastatic gastrointestinal stromal tumor (GIST) after previous failed extensive therapy, including multiple surgeries and hepatic artery embolization. Within a few months of starting administration of imatinib mesylate, the patient exhibited a clinical response with grade 3 neutropenia, when pulmonary tuberculosis developed. A c-kit mutation in exon 11 was detected only in metastatic liver specimens. It is unclear whether or not pulmonary tuberculosis may be induced by imatinib mesylate treatment, but caution is warranted in immunocompromised GIST patients. This is the first report of tuberculosis associated with neutropenia during imatinib mesylate treatment.     

Aging of the autonomic nervous system

Aging is associated with structural and functional changes in the autonomic nervous system (ANS), which innervates the whole body, and its altered function may influence almost all body systems. Changes related to aging are found in autonomic nerves and ganglia, and ANS controlled functions including cardiovascular functions. Much of the current knowledge about age-related changes in sympathetic nervous function is derived from studies of circulating catecholamine levels, norepinephrine kinetics and microneurographic recordings from sympathetic nerves of skeletal muscle. Significant evidence suggests that basal plasma noradrenaline levels increase with age. These data indicates that healthy aging is associated with elevated basal sympathetic nervous activity. In contrast, the reactivity of the sympathetic and the parasympathetic nervous activity are reduced with aging.