Impact of Light Shielding on Photo-Degradation of Dacarbazine during the Preparation Process.

Dacarbazine (DTIC) is converted to the photo-degradation product 4-diazoimidazole-5-carboxamide (Diazo-IC) by light. Diazo-IC production is often responsible for the pain reactions observed during peripheral intravenous infusion of DTIC in clinical settings. Although light shielding during infusion decreases the photo-degradation of DTIC, its usefulness for the preparation of DTIC has not yet been fully clarified. The aim of this study was to investigate the light conditions during the preparation of DTIC solution in the compounding room from the viewpoint of the production amount of Diazo-IC. DTIC solution was prepared in the compounding room. Various light and temperature conditions and dissolving solutions during the preparation were investigated. The amounts of DTIC and Diazo-IC in solutions were determined using an HPLC coupled to UV detection. The photo-degradation of DTIC was estimated by the amount of Diazo-IC. Diazo-IC production in the dissolving solutions increased in a time-dependent manner at 4 and 25°C under light shielding. Light exposure during the dissolving process did not affect the DTIC and Diazo-IC concentrations. Light shielding during dissolution did not alter the Diazo-IC production until 4 h after dilution. In conclusion, short duration light exposure did not affect Diazo-IC production. These findings suggest that light shielding is not needed in the preparation of DTIC in the compounding room from the viewpoint of Diazo-IC production.

Intraoperative Neural Mobility and Postoperative Neurological Recovery in Anterior Cervical Decompression Surgery: Evaluation With Intraoperative Sonography.

STUDY DESIGN: A study using intraoperative sonography (IOS) was conducted for evaluating neural mobility in anterior cervical decompression surgery. OBJECTIVES: To analyze decompression status and mobility of the spinal cord and the nerve root during anterior cervical decompression and to clarify its relevance to the postoperative neurological recovery. SUMMARY OF BACKGROUND DATA: Several papers introduced the usefulness of IOS assessments; however, there have been no reports systematically evaluating the neural mobility in anterior cervical decompression surgery. METHODS: Eighty-four consecutive patients with compressive myelopathy who underwent anterior cervical decompression procedures were studied. The decompression status of the spinal cord was evaluated with IOS and classified into 3 grades according to the restoration pattern of the space ventral to the cord. Pulsatile motion of the spinal cord in cranio-caudal direction was named "sliding pulsation" and graded into 3 groups. The nerve root pulsation was also assessed using the IOS short-axis views. This study analyzed whether those neural mobility in anterior cervical decompression surgery had relevance to postoperative neurological recovery, which was assessed by the Japan Orthopaedic Association score. RESULTS: The mean recovery rate of the Japan Orthopaedic Association score was 59.1% in total. According to the decompression status in IOS, 67 patients who acquired space ventral to the spinal cord indicated 64.3% of the recovery rate which was significantly higher than 36.6% of the other patients on an average. As to the sliding pulsation of the cord, 10 patients who failed to show this particular motion indicated significantly lower recovery rate as 36.9%. In addition, 6 patients who did not exhibit nerve root pulsation indicated just 29.3% of recovery rate, and 4 of them failed to show the cord sliding motion. CONCLUSIONS: Sonographic evaluation during anterior cervical decompression surgery provided very useful information of neural decompression status that had significant correlation with postoperative neurological recovery.

Spatial distributions of and diurnal variations in low molecular weight carbonyl compounds in coastal seawater, and the controlling factors.

We studied the spatial distributions of and the diurnal variations in four low molecular weight (LMW) carbonyl compounds, formaldehyde, acetaldehyde, propionaldehyde, and glyoxal, in coastal seawater. The samples were taken from the coastal areas of Hiroshima Bay, the Iyo Nada, and the Bungo Channel, western Japan. The formaldehyde, acetaldehyde, and glyoxal concentrations were higher in the northern part of Hiroshima Bay than at offshore sampling points in the Iyo Nada and the Bungo Channel. These three compounds were found at much higher concentrations in the surface water than in deeper water layers in Hiroshima Bay. It is noteworthy that propionaldehyde was not detected in any of the seawater samples, the concentrations present being lower than the detection limit (1 nanomole per liter (nM)) of the high performance liquid chromatography (HPLC) system we used. Photochemical and biological experiments were performed in the laboratory to help understand the characteristic distributions and fates of the LMW carbonyl compounds. The primary process controlling their fate in the coastal environment appears to be their biological consumption. The direct photo degradation of propionaldehyde, initiated by ultraviolet (UV) absorption, was observed, although formaldehyde and acetaldehyde were not degraded by UV irradiation. Our results suggest that the degradation of the LMW carbonyl compounds by photochemically formed hydroxyl radicals is relatively insignificant in the study area. Atmospheric deposition is a possible source of soluble carbonyl compounds in coastal surface seawater, but it may not influence the carbonyl concentrations in offshore waters.

Lipid rafts serve as signaling platforms for Tie2 receptor tyrosine kinase in vascular endothelial cells.

The Tie2 receptor tyrosine kinase plays a pivotal role in vascular and hematopoietic development. The major intracellular signaling systems activated by Tie2 in response to Angiopoietin-1 (Ang1) include the Akt and Erk1/2 pathways. Here, we investigated the role of cholesterol-rich plasma membrane microdomains (lipid rafts) in Tie2 regulation. Tie2 could not be detected in the lipid raft fraction of human umbilical vein endothelial cells (HUVECs) unless they were first stimulated with Ang1. After stimulation, a minor fraction of Tie2 associated tightly with the lipid rafts. Treatment of HUVECs with the lipid raft disrupting agent methyl-beta-cyclodextrin selectively inhibited Ang1-induced Akt phosphorylation, but not Erk1/2 phosphorylation. It has been reported that inhibition of FoxO activity is an important mechanism for Ang1-stimulated Tie2-mediated endothelial function. Consistent with this, we found that phosphorylation of FoxO mediated by Tie2 activation was attenuated by lipid raft disruption. Therefore, we propose that lipid rafts serve as signaling platforms for Tie2 receptor tyrosine kinase in vascular endothelial cells, especially for the Akt pathway.

Involvement of MDR1 function in proliferation of tumour cells.

Mdr1 is a multi-drug-resistance protein, a member of the adenosine triphosphate-binding cassette family of drug transporters. Mdr1 is expressed in wide variety of cells and limits absorption of toxicants into the body or tissue; however, it is also expressed in many cancer cells and can render tumour cells resistant to many anti-cancer drugs. Mdr1 is well studied as a multi-drug resistance transporter, but little is known regarding its other role in tumour cells. In the present study, we investigated mdr1 function in tumour cell proliferation. We silenced the mdr1 gene in tumour cells by using an RNA interference method that employed short hairpin RNA. The result showed that knockdown of mdr1 gene suppressed tumour cell proliferation in vitro, and induced the passage of the cell cycle into the G1/G0 phase. Furthermore, in a mice xenograft tumour formation assay, mdr1 knockdown of tumour cells inhibited tumour expansion. These results suggest that Mdr1 plays a role in regulation of tumour cells proliferation.

EphB4 overexpression in B16 melanoma cells affects arterial-venous patterning in tumor angiogenesis.

EphB4 receptor and its ligand ephrinB2 play an important role in vascular development during embryogenesis. In blood vessels, ephrinB2 is expressed in arterial endothelial cells (EC) and mesenchymal supporting cells, whereas EphB4 is only expressed in venous ECs. Previously, we reported that OP9 stromal cells, which support the development of both arterial and venous ECs, in which EphB4 was overexpressed, could inhibit ephrinB2-positive (ephrinB2+) EC development in an embryonic tissue organ culture system. Although the EphB4 receptor is expressed in a variety of tumor cells, its exact function in regulating tumor progression has not been clearly shown. Here we found that overexpression of EphB4 in B16 melanoma cells suppressed tumor growth in a s.c. transplantation tumor model. Histologic examination of these tumors revealed that EphB4 overexpression in B16 cells selectively suppressed arterial ephrinB2+ EC development. By coculturing ephrinB2-expressing SV40-transformed mouse ECs (SVEC) with EphB4-overexpressing B16 cells, we found that EphB4 induced the apoptosis of SVECs. However, ephrinB2 did not induce the apoptosis of EphB4-overexpressing B16 cells. Based on results from these experiments, we concluded that EphB4 overexpression in B16 tumor cells suppresses the survival of arterial ECs in tumors by a reverse signaling via ephrinB2.

Rapid and highly sensitive determination of low-molecular-weight carbonyl compounds in drinking water and natural water by preconcentration HPLC with 2,4-dinitrophenylhydrazine.

The aim of this research was to develop a simple procedure for a highly sensitive determination of low-molecular-weight (LMW) carbonyl compounds in drinking water and natural water. We employed a preconcentration HPLC system with 2,4-dinitrophenylhydrazine (DNPH) for the determination of LMW carbonyl compounds. A C-18 reverse-phase preconcentration column was used instead of a sample loop at the sample injection valve. A 0.1 - 5.0 mL portion of the derivatized sample solution was injected with a gas-tight syringe, and a 15% acetonitrile aqueous solution was pushed through the preconcentration column to remove the unreacted excess DNPH, which caused serious interference in the determination of formaldehyde. The detection limits were 1 - 3 nM with a relative standard deviation of 2 - 5% for 20 nM standard solutions (n = 5). The calibration curves were essentially unaffected by coexisting sea salts. Applications to commercial mineral water, tap water, river water, pond water and seawater are presented.

Preventive effects of a water-soluble derivative of chroman moiety of vitamin E on lipid hydroperoxide-induced cell injuries and DNA cleavages through repressions of oxidative stress in the cytoplasm of human keratinocytes.

ChrCrx (6-hydroxy-2, 5, 7, 8-tetramethyl-chroman-2-carboxylic acid) is a water-soluble analog in which 4', 8', 12'-trimethyltridecyl chain is deleted from an alpha-tocopherol molecule known as a hydrophobic antioxidant. Cell viability of human skin epidermal keratinocytes HaCaT was lowered by treatment with tert-butylhydroperoxide (t-BuOOH) of 50 microM for 48 h, designated as a subacute cytotoxicity, which was prevented by previous administration with ChrCrx in a dose-dependent manner as estimated by mitochondrial function-based WST-1 assay and cell morphological microscopy. In contrast an acute cytotoxicity due to treatment with t-BuOOH as dense as 200 microM for a period as short as 2 h could be also prevented with ChrCrx that was administered before and after, but was eliminated during, treatment with t-BuOOH. In contrast alpha-tocopherol was not cytoprotective against t-BuOOH. DNA strand cleavages were induced with t-BuOOH in the keratinocytes, and could be prevented by ChrCrx more effectively than alpha-tocopherol as assayed by TUNEL stain. The intracellular reactive oxygen species (ROS) was accumulated in a manner dependent on periods of t-BuOOH treatment in the cytoplasm more abundantly rather than the nucleus of keratinocytes, and was markedly diminished by ChrCrx as shown by fluorography using the redox indicator dye. Thus t-BuOOH-induced cell injuries and DNA cleavages of the keratinocytes can be prevented at least in part through efficient diminishment of ROS generated in the cytoplasm, to which the preferred distribution of ChrCrx may be advantageous over to the nucleus or membrane owing to its molecular hydrophilicity relative to alpha-tocopherol.