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To elucidate the pathophysiology of crescentic glomerulonephritis, we investigated the effects of basic fibroblast growth factor(Bfgf) on cultured rat parietal epithelial cells(PEC). Cultured cells were characterized as PEC by morphologic and immunohistochemical findings. PEC were cultured with or without various concentrations of Bfgf, 1, 5, 25, and 50ng/ml for 0, 24, 48, and 96 hours. We found that Bfgf is mitogenic to PEC in vitro at high concentrations and short-term incubation by direct cell counting and [H]-thymidine incorporation assay. Also, cell viability evaluated by trypan-blue test increased at 5 and 25ng/ml of Bfgf and decreased with time. We utilized the radionuclidelabeled precursors of extracellular matrix(ECM), glycosamine, leucine, and sulfate, for the assay of the utilization of those precursors by PEC. The utilization of [H]-glycosamine showed the tendency of increase with exposed time at higher concentrations although it increased at concentration of 5ng/ml in 24 hours. The utilization of [H]-leucine increased in 24 hours exposure time at concentration of 5ng/ml and in longer time at higher concentrations. Whereas, the utilization of [S]-sulfate increased in 24 hours exposure time to Bfgf at each concentration. Thus, Bfgf may augment PEC proliferation and ECM production by cultured PEC and this could explain the role of Bfgf in the pathophysiology of crescentic glomerulonephritis. The further experiments might be needed to elucidate the role of Bfgf in molecular level.
Attenuation correction is important in producing quantitative positron emission tomography (PET) images. Conventionally, photon attenuation effects are corrected using transmission measurements performed before tracer administration. The pre-injection transmission measurement approach may require a time delay between transmission and emission scans for the tracer studies requiring a long uptake period, about 45 minutes for F-18 deoxyglucose study. The time delay will limit patient throughput and increase the 1ikelihood of patient motion. A technique for performing simultaneous transmission and emission scans (T+E method) after the tracer injection has been validated. The T+E method substracts the emission counts contaminating the transmission measurements to produce accurate attenuation correction coefficients. This method has been evaluated in experiments using a cylindrical phantom filled with background water (5750 cc) containing 0.4 μCi/cc of F-18 fluoride ion and one insert cylinder (276 cc) containing .3 μCi/cc. GE AdvanceTM PET scanner and Ge-68 rotating pin sources for transmission scanning were used for this investigation. Post-injection transmission scan and emission scan were performed alternatively over time. The error in emission images corrected using post-injection transmission scan to emission images corrected using post-injection transmission scan to emission images corrected transmission scan was 2.6% at the concentration of 1.0 μCi/cc. No obvious differences in image quality and noise were apparent between the two images. The attenuation correction can be accomplished with post-injection transmission measurement using rotating pin sources and this method can significantly shorten the time between transmission and emission scans and thereby reduce the likelihood of patient motion and increase scanning throughput in PET.
A series of performance measurements of positron emission tomography (PET) were performed following the recommendations of the Computer and Instrumentation Council of the Society of Nuclear Medicine and the National Electrical Manufacturers Association. We investigated the performance of the General Electric AdvanceTM PET. The measurements include the basic intrinsic tests of spatial resolution, scatter fraction, sensitivity, and count rate losses and randoms. They also include the tests of the accuracy of corrections: count rate linearity correction, uniformity correction, scatter correction and attenuation correction. GE Advance^(TM) PET has bismuth germanate oxide crystals (4.0mm transaxial × 8.lmm axial × 30.0mm radial) in 18 rings, which form 35 imaging planes spaced by 4.25mm. The system has retractable tungsten septa 1mm thick and 12cm long. Transaxial resolution was 4.92mm FWHM in 2D and 5.14mm FWHM in 3D at the center. Average axial resolution in 2D decreased from 3.91mm FWHM at the center to 6.49mm FM at R=20cm. Average scatter fraction of direct and cross slices was 9.57%. Dead-time losses of 50% corresponded to a radioactivity concentration of 4.86μCi/cc and a true count rate of 519 kcps in 2D. The accuracy of count rate linearity correction was 1.84% at the activity of 4.50μCi/cc. Non-uniformity was 2.06% in 2D and 2.93% in 3D. Remnant errors after scatter correction were 0.55% in 2D and 4.12% in 3D. The errors of attenuation correction were 6.21% (air), 0.20% (water), -6.32% (teflon) in 2D and 5.00% (air), 6.94% (water), 3.01% (teflon) in 3D. The results indicate the performance of GE Advance^(TM) PET scanner to be well suited for clinical and research applications.
Effects of plating conditions such as electropolishing, an organic solution in electrolyte and vacuum aging on the wear and corrosion resistance of hard chrome deposits on the AISI 1024 steel were studied to improve the performance of the deposits. For the plating conditions of 0.6A/㎠ at 53℃, electropolishing in the electrolyte with phosphoric acid for 1 minute followed by 30 seconds in plating bath showed the best neutral salt fog spray life among the chrome coatings prepared for this study. The contamination of the plating bath with the phosphoric acid reduced the cathodic current efficiency. Chrome plated in modified Sargent bath containing Formic acid had amorphous structure supersaturated with carbon up to 2.0wt.%, which precipitated as chrome carbide such as Cr_(23)C_6 after vacuum aging above 200℃ for 1 hour. This resulted in improvement of hardness and wear resistance of the chrome layer. Considering the reduction of corrosion resistance due to the thermal effect, optimum vacuum aging condition of the chrome layer was 1 hour at 200℃
The purpose of this study was to determine the relationships between schoolchildren's apolipoprotein levels and coronary or cerebral events in their older family members. Study population consisted of 269 elementary schoolchildren aged 6 to 11 years (145 boys and 124 girls) in Seoul, Korea. We measured the blood concentrations of total cholesterol, apolipoproteins B and A-1, and lipoprotein(a), and questioned parents about coronary or cerebral vascular events in children's older family members. The results were analyzed statistically. Apo B, A-1 and Lp(a) levels showed significant increment with aging. The levels of apo B, A-1, Lp(a) and apo B/apo A-1 ratio were significantly high in the hypercholesterolemic group. The levels of total cholesterol, apo B, Lp(a), and apo B/apo A-1 ratio in the obese group differed significantly from those in the non-obese group. There was a significant difference in the mean concentration of Lp(a)(17.4±3.6g/L) of the children who had positive family histories of coronary or cerebral events in comparison with that(8.6±3.6g/L) of the children with negative history. Family history was an independent and major contributor to high Lp(a) in any cases. In evaluating children's lipid profiles, measurement of Lp(a) may help to identify children and their families at increased risk and may facilitate the targeting of prevention.
For the purpose of evaluating the origin of cultured glomerular epithelial cells(GEC), we applied immunohistochemical(IHC) and electron microscopic (EM) studies to characterize the cultured rat GEC. After isolation by differential sieving method, glomeruli were explanted and maintained in a medium(K1-3T3) consisting of equal parts of a Kl medium and conditioned medium taken from cultures of NIH 3T3 fibroblasts grown in Dulbecco's modified Eagle's mediurn plus 10% fetal calf serum. Morphologically distinct GEC grew out from the isolated glomeruli and they were cultured continuously. The grown GEC(early stage within 7 days after glomerular explantation) and continuously cultured cells were characterized by IHC using primary antibodies, such as, monoclonal antibodies to cytokeratin, desmin, Thy 1.1, and vimentin and EM methods. At the sarne time, their results were compared with those of glomerular epithelium from rat kidney sections. The inverted light microscopic features of continuously cultured GEC were similar to those of primarily cultured GEC. Both prirnarily and continuously cultured GEC stained positive for cytokeratin and negative for desmin, Thy 1.1, and vimentin, which results were identical to the IHC results of parietal cells in situ. On the contrary, visceral epithelial cells in situ stained positive for vimentin and desmin and negative for cytokeratin. These results suggested that rat GEC in primary and continuous culture, expressed IHC characteristics of in situ parietal, not visceral epithelium. We could observe junctional complexes of the desmosome type in cultured GEC which were noted in parietal epithelial cells, not in visceral cells. In conclusion, the cultured epithelial cells might be glomerular parietal epithelial cells by comparing the IHC and EM characteristics of cultured GEC with glomerular epithelium from rat kidney sections. Therefore, we can use these cultured and characterized glomerular parietal epithelial cells (GPEC) for the study of their biologic functions or of the pathophysiology of GPEC-associated diseases, such as, crescentic glomerulonephritis.