Handling of doxorubicin by the LLC-PK1 kidney epithelial cell line

The characteristics of doxorubicin handling have been studied in the cultured kidney epithelial cell line LLC-PK1, which has structure and function similar to those of renal tubular cells and expresses P-glycoprotein. The uptake of doxorubicin by LLC-PK1 cells was time dependent, reaching a steady state at about 4 hr, and reduced at low temperature; the initial uptake was saturable. The efflux of doxorubicin from LLC-PK1 cells was also temperature dependent but, even at 37 degrees C, a significant percentage of the drug remained associated with the cells after 180 min, which suggests a strong cellular binding, and the fluorescence microscopy revealed that the drug was concentrated in intracellular organelles. Substances that are substrates for P-glycoprotein, such as verapamil, vinblastine, vincristine and quinidine, significantly increased doxorubicin concentrations in LLC-PK1 cells. Similar results were obtained with the metabolic inhibitors sodium metavanadate and 2,4-dinitrophenol. On the other hand, the uptake was not affected by the classic organic cation transport drugs cimetidine, decynium 22 or decynium 24, nor by the organic anion drug probenecid. These results indicate that, in LLC-PK1 cells, doxorubicin enters by passive diffusion, is trapped in intracellular organelles and then is extruded from cells by a mechanism that probably involves P-glycoprotein. On the contrary, substances that interfere with the renal organic cation or anion secretory system have no effect on doxorubicin net accumulation in these cells.     

美国印刷市场"冷""热"情报

序言 印刷品在各大应用领域的"冷""热"与该领域市场对印刷品的需求直接相关,而需求的增减又依赖于这一市场是景气还是衰退.本文作者是美国印刷界知名的市场"预报员"和推荐者,他认为消费者已经为整体经济增长费用超支,因此零售商为了扩大销售将添加目录、再订购点(ROP)和户外/购买点(POP)宣传所需材料,以便引起消费者的购买欲;此外对海外收入和资金的日益依赖将意味着需要更多多语种(multi-lingual)的广告和包装;同时业务合并也将导致名称的改变,从而掀起一股从商业卡片到户外标识的印刷热浪.     

Phospholipid film in electrolyte-gated organic field-effect transistors

A totally innovative electrolyte-gated field effect transistor, embedding a phospholipid film at the interface between the organic semiconductor and the gating solution, is described. The electronic properties of OFETs including a phospholipid film are studied in both pure water and in an electrolyte solution and compared to those of an OFET with the organic semiconductor directly in contact with the gating solution. In addition, to investigate the role of the lipid layers in the charge polarization process and quantify the field-effect mobility, impedance spectroscopy was employed. The results indicate that the integration of the biological film minimizes the penetration of ions into the organic semiconductor thus leading to a capacitive operational mode as opposed to an electrochemical one. The OFETs operate at low voltages with a field-effect mobility in the 10⁻³ cm² V⁻¹ s⁻¹ range and an on/off current ratio of 10³. This achievement opens perspectives to the development of FET biosensors potentially capable to operate in direct contact with physiological fluids.     

Stimulation of rat peritoneal mast cells induces phagocytosis of adriamycin by rat peritoneal macrophages

Rat and beige mouse peritoneal mast cells, induced to exocytose with the antineoplastic agent adriamycin, extrude their granule remnants in the extracellular medium. These granules are loaded with the fluorescent drug adriamycin and exhibit intense yellow-reddish fluorescent staining. Granules extruded from mast cells were ultimately phagocytosed and could be observed inside the macrophages by fluorescence microscopy. All stages of the internalization process could be followed by electron microscopy. Granules adhering to the cell surface of macrophages were first embraced by short superficial projections, then enveloped by deep surface infoldings, and finally engulfed into the macrophage cytoplasm. Phagocytosis occurred exclusively in macrophages; granules were observed also on the surface of eosinophils and lymphocytes, but never inside these cells. The concentrations of adriamycin in macrophages, measured by spectrofluorimetry, were significantly higher when these cells were incubated with adriamycin and granule remnants in comparison with adriamycin alone. Preincubation with the endocytosis inhibitor cytochalasin B significantly reduced the granule mediated adriamycin uptake. As a consequence of the phagocytosis of adriamycin loaded mast cell granules, macrophages can concentrate the antineoplastic drug. These cells act as reservoirs of adriamycin and could have an important role in both the antitumor and toxic effects of the drug.     

The sinus endothelial cell architecture in the mouse lymph node. Structural peculiarities and close correlation with the fibroblastic reticular cells

We evaluated the performance of a direct Liquid N-geneous HDL-C assay (N-HDL; Genzyme Diagnostics, Cambridge, Mass) and compared it with a Centers for Disease Control and Prevention (CDC) modified reference procedure (M-REF) and phosphotungstic acid (PTA) precipitation method in patients with normotriglyceridemia (triglyceride level, <400 mg/dL) and hypertriglyceridemia (triglyceride level, > or =400 mg/dL). Excellent intra-assay and interassay coefficients of variation were obtained (<2.0%) using the N-HDL assay. The N-HDL and PTA assays correlated well with M-REF in normotriglyceridemic samples. In hypertriglyceridemic samples, however, the N-HDL method exhibited better correlation with M-REF than the PTA assay. In addition, compared with M-REF, the mean absolute percentage bias of N-HDL was lower than the PTA assay in normotriglyceridemic (4.9% vs 5.8%) and hypertriglyceridemic (5.4% vs 12.9%) samples. Hemolysis, ascorbic acid, and bilirubin did not interfere with the N-HDL assay. On the basis of these findings, the N-HDL assay compares favorably with the modified CDC reference method and seems superior to the PTA assay. It also has the advantage of being suited for complete automation and, thus, would prove useful in large clinical laboratories.