Asymmetric inhibition of spicule formation in sea urchin embryos with low concentrations of gadolinium ion.

As gastrulation proceeds during sea urchin embryogenesis, primary mesenchyme cells (PMCs) fuse to form syncytial cables, within which calcium is deposited as CaCO3, and a pair of spicules is formed. Earlier studies suggested that calcium, previously sequestered by primary mesenchyme cells, is secreted and incorporated into growing spicules. We examined the effects of gadolinium ion (Gd(3+)), a Ca(2+) channel blocker, on spicule formation. Gd(3+) did not lead to a retardation of embryogenesis prior to the initiation of gastrulation and did not inhibit the ingression of PMCs from the blastula wall or their migration along the inner blastocoel surface. However, when embryos were raised in seawater containing submicromolar to a few micromolar Gd(3+), of which levels are considered to be insufficient to block Ca(2+) channels, a pair of triradiate spicules was formed asymmetrically. At 1-3 µmol/L Gd(3+), many embryos formed only one spicule on either the left or right side, or embryos formed a very small second spicule. Induction of the spicule abnormality required the presence of Gd(3+) specifically during late blastula stage prior to spicule formation. An accumulation or adsorption of Gd(3+) was not detected anywhere in the embryos by X-ray microanalysis, which suggests that Ca(2+) channels were not inhibited. These results suggest that Gd(3+) exerts an inhibitory effect on spicule formation through a mechanism that does not involve inhibition of Ca(2+) channels.

Inhibition of heme oxygenase-1 with an epidermal growth factor receptor inhibitor and cisplatin decreases proliferation of lung cancer A549 cells.

Heme oxygenase-1 (HO-1) is induced by a variety of stress stimuli and by many antitumor agents. We investigated involvement of HO-1 in chemoresistance of cisplatin in human lung epithelial adenocarcinoma cell line, A549, which constitutively expressed HO-1. We found that treatment with cisplatin further augmented HO-1 expression, which was associated with activation of the epidermal growth factor receptor (EGFR) mediated signaling pathway and subsequent nuclear translocation of NF-kappaB. In concordance with the findings, treatment with EGFR-selective tyrosine kinase inhibitor (AG1478) or an Akt inhibitor, which interfere with the post-EGFR signaling pathway, suppressed cisplatin induced HO-1 expression. While either AG1478 or HO-1 siRNA alone did not alter cell viability of A549 cells, both agents significantly augmented cytotoxicity of cisplatin. The similar data also found in large cell carcinoma cell line, H460. Collectively, the results indicate that resistance to cisplatin in A549 cells is associated with HO-1 through EGFR mediated signaling pathway including activation of the PI3k/Akt and NF-kappaB systems. Our data also suggest that the chemosensitivity of A549 cells to cisplatin is restored by EGFR-selective tyrosine kinase inhibitor and an Akt inhibitor.

The efficacy of high-dose penicillin for community-acquired pneumonia diagnosed by pneumococcal urine antigen test.

We analyzed the efficacy of both the Streptococcus pneumoniae urine antigen test as a quick diagnostic tool and the administration of high-dose penicillin in response to a positive S. pneumoniae urine antigen test. We conducted a retrospective analysis of 48 cases of pneumococcal pneumonia, in which the patients were treated with high-dose penicillin. All the cases were diagnosed by a positive urine antigen test. Treatment with high-dose penicillin was effective in 43 of the 48 patients. This treatment was also effective in 12 of 16 culture-confirmed cases with low susceptibility to penicillin. Eleven patients who were positive for the S. pneumoniae urine antigen test but culture-negative showed clinical improvement with high-dose penicillin. Pneumonia caused by S. pneumoniae appeared to be treated safely and effectively with high-dose penicillin based on positive results of the urine antigen test, as penicillin resistance was unlikely to be a problem.

Development of calcium releasing activity induced by inositol trisphosphate and cyclic ADP-ribose during in vitro maturation of sea urchin oocytes.

During fertilization of sea urchin eggs, the cytoplasmic Ca(2+) concentration ([Ca(2+)](i)) transiently increases (Ca(2+) transient). Increased [Ca(2+)](i) results from a rapid release from intracellular stores, mediated by one or both of two signaling pathways; inositol 1,4,5-trisphosphate (IP(3)) and IP(3) receptor (IP(3)R) or cyclic GMP (cGMP), cyclic ADP-ribose (cADPR) and ryanodine receptor (RyR). During fertilization, cGMP and cADPR increase preceding the Ca(2+) transient, suggesting their contribution to this. If the RyR pathway contributed to the Ca(2+) transient, its Ca(2+) releasing activity would develop in parallel with that of the IP(3) system during maturation of oocytes. Sea urchin oocytes were cultivated in vitro and Ca(2+) transients induced by photolysis of caged IP(3) or caged cADPR were measured during maturation. Oocytes spontaneously began to maturate in seawater. More than 50% of oocytes underwent germinal vesicle breakdown within 25 h and the second meiosis within 35 h, but it took more than 24 h until they became functionally identical to in vivo-matured eggs. Both IP(3) and cADPR induced Ca(2+) transients comparable to those of in vivo-matured eggs later than 24 h from the second meiosis. However, cADPR induced a small Ca(2+) transient even before meiosis, whereas IP(3) and sperm almost did not.