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Factor Concentration (factor + concentration)
Selected AbstractsEffects of Time of Collection and Sample Processing on von Willebrand Factor Concentration in Retired Racing GreyhoundsJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 6 2008L.M. Marín Background: Concentrations of von Willebrand factor (vWF) are less than 30% in approximately 10% of Greyhounds. Hypothesis: That sample collection, processing, and storage can affect the concentration of vWF in plasma of Greyhounds. Animals: Nineteen healthy former racing Greyhounds. Methods: Prospective study: Blood samples were obtained from the jugular vein of dogs at 4 times during the day. Samples were divided and processed in each of 3 ways. The 1st tube was centrifuged immediately, the 2nd tube was kept in a household refrigerator, and the 3rd tube was kept at room temperature for 3 hours before centrifugation and processing. Results: There were no significant differences in the vWF concentration between different sample storage and processing (P=5.31). There was no statistically significant diurnal variation in vWF concentration in the samples evaluated (P=.37). Conclusions and Clinical Importance: Time of sample collection and short-term storage temperature do not influence the vWF concentration in retired racing Greyhounds. [source] Thrombin generation in haemophilia A patients with mutations causing factor VIII assay discrepancyHAEMOPHILIA, Issue 4 2010R. GILMORE Summary., Up to 40% of patients with mild haemophilia A have a discrepancy whereby factor VIII (FVIII) measurements by a two-stage chromogenic assay (FVIII:CCH) are disproportionately reduced compared with the FVIII one-stage clotting value (FVIII:C). Which assay best reflects the coagulation potential and clinical phenotype in this patient group is of clinical significance, yet remains unclear. We have assessed the global coagulant ability of haemophilia patients with FVIII assay discrepancy using calibrated automated thrombography (CAT). A total of 18 patients with mutations Arg531His/Cys or Arg698Trp causing FVIII discrepancy were investigated, together with 12 haemophilia patients with concordant FVIII values and 15 normal controls. Factor VIII levels in all patients and controls were measured using both one-stage clotting assay and two-stage chromogenic assay. Thrombin generation was assessed in platelet-poor plasma by CAT using a low tissue factor concentration (1 pm). FVIII:CCH values were below normal in all patients, and in the discrepant group were between 1.5- and 8-fold lower than FVIII:C values. CAT parameters were affected in all haemophilia patients. The endogenous thrombin potential (ETP) was reduced to 58,67% of the mean normal value (1301 nm min,1), whereas peak thrombin was further reduced to 27,30% of the mean normal value (178 nm) in both discrepant and concordant patient groups. Analysis of the discrepant patient group showed the most significant correlation between the one-stage FVIII:C assay and ETP (r2 = 0.44) and peak thrombin parameters (r2 = 0.27). [source] Inhibition of heme oxygenase-1 by zinc protoporphyrin IX reduces tumor growth of LL/2 lung cancer in C57BL miceINTERNATIONAL JOURNAL OF CANCER, Issue 3 2007Kaeko Hirai Abstract Heme oxygenase (HO)-1 is a key player reducing cytotoxicity and enhancing protumoral effects of nitric oxide (NO). We examined zinc protoporphyrin (ZnPP) IX, an HO-1 inhibitor, to affect tumor growth of LL/2 mouse lung cancer cells. ZnPPIX reduced HO-1 expression and HO activity in LL/2 cells, whereas cobalt PPIX (CoPPIX), an HO-1 activator, increased both. LL/2 cells treated with sodium nitropurusside, an NO donor, showed growth inhibition dose-dependently, which was enhanced by ZnPPIX cotreatment, but was reduced by CoPPIX. In mice tumors, ZnPPIX decreased HO-1 expression. LL/2-tumors were found in 88% (7/8) vehicle-treated mice, whereas tumors were found in 38% (3/8) and 25% (2/8) mice treated with 5 and 20 ,g/mouse ZnPPIX, respectively (p = 0.0302). Tumor growth was inhibited dose-dependently by ZnPPIX. Vascular endothealial growth factor concentration in tumors was reduced by ZnPPIX (p = 0.0341). Microvessel density (MVD) in ZnPPIX-treated tumors was lower than that in vehicle-treated tumors (p = 0.0362). Apoptotic cell count in ZnPPIX-treated tumors was higher than that in vehicle-treated tumors (p = 0.0003). In contrast, CoPPIX treatment increased HO-1 expression, enhanced tumorigenicity and MVD and reduced apoptosis. From these findings, inhibition of HO-1 by ZnPPIX provides relevant antitumoral effects. © 2006 Wiley-Liss, Inc. [source] Response of Globodera rostochiensis to exogenously applied hatching factors in soilANNALS OF APPLIED BIOLOGY, Issue 1 2000K J DEVINE Summary The exogenous application of hatching factors (HFs) to soil in the field gave an approximately 50% reduction in the population size of Globodera rostochiensis. This control was found to be due to a combination of suicide hatch and increased in-egg mortality caused presumably by incomplete hatch stimulation. The rates of hatch and emergence of J2s from cysts of G. rostochiensis were found to be dependent on hatching factor concentration in vitro and in the field. Encysted eggs of G. rostochiensis in the field during the first year of rotation after the previous year's potato crop were found to be more sensitive to HF concentration than those in the second year of rotation. [source] Effects of lyophilization on human amniotic membraneACTA OPHTHALMOLOGICA, Issue 4 2009M. Teresa Rodríguez-Ares Abstract. Purpose:, This study aimed to evaluate the effects of lyophilization and cryopreservation on human amniotic membrane (HAM) in terms of histological characteristics and growth factor levels. Methods:, Non-preserved, lyophilized and cryopreserved HAM samples from 13 placentas were investigated. The morphological characteristics of HAM were evaluated using light and electron microscopy. Immunohistochemical methods were also applied to assess the distribution of collagen IV in the basement membrane. Total protein amounts were measured in extracts of intact amniotic membrane from non-preserved, lyophilized and cryopreserved samples. An enzyme-linked immunosorbent assay (ELISA) was used to assay growth factor protein levels for epidermal growth factor, fibroblast growth factor basic, hepatocyte growth factor, keratinocyte growth factor, transforming growth factor-,1 and nerve growth factor. Results:, Histological examination of lyophilized and cryopreserved human amniotic membrane showed similar results. Immunohistochemistry showed presence of collagen IV throughout the basement membrane, both in cryopreserved and lyophilized samples. Total protein amount was higher in cryopreserved samples, without statistical significance. Growth factors ELISA did not show statistically significant differences except for fibroblast growth factor basic, with higher levels in cryopreserved amniotic membrane. Conclusions:, Lyophilization maintains the histological structure of HAM, but seems to cause greater reductions in total protein amount and growth factor concentration than cryopreservation. [source] Time- and dose-dependent mitogenic effect of basic fibroblast growth factor combined with different bone graft materials: an in vitro studyCLINICAL ORAL IMPLANTS RESEARCH, Issue 5 2006Xanthippi E. Dereka Abstract Objectives: In periodontal regeneration, the growth factor concentrations and the delivery system used are of great importance. In an attempt to assess the mitogenic effect of basic fibroblast growth factor (bFGF) on periodontal ligament (PDL) cells combined with different bone replacement materials, two allografts of cortical (DFDBA) and cancellous (DFBA) bone and an anorganic bovine material with a synthetic peptide (ABM P-15) were used. The purpose of this study was to evaluate the in vitro mitogenic effect of different doses of bFGF alone or in combination with DFDBA, DFBA and ABM P-15 on human PDL cells in a time-dependent mode. Material and methods: PDL cell cultures were derived from the mid-root of four maxillary premolars. Cells were grown and reached confluence. On day 2 of quiescence, new medium was added along with (1) 1, 5, 10 and 25 ng/ml of bFGF alone, (2) 10 mg of DFDBA, DFBA and ABM P-15 alone and (3) their combination. The mitogenic effect was determined at 24 and 48 h of culture by using a hemocytometer chamber. The cells were counted under a phase contrast microscope. Results: The results revealed that bFGF at the highest concentrations and after 48 h exerted a significant mitogenic effect on PDL cells, and also DFDBA and DFBA supported cell proliferation. Furthermore, DFDBA and DFBA enriched with bFGF had a significant mitogenic effect after 48 h of culture. ABM P-15 with 10 and 25 ng/ml of bFGF up-regulated PDL cell proliferation after 48 h of incubation. Conclusions: The findings of this study demonstrate the beneficial role of bFGF combined with DFDBA and DFBA as carriers in periodontal repair. [source] Analysis of nodulation kinetics in Frankia,Discaria trinervis symbiosis reveals different factors involved in the nodulation processPHYSIOLOGIA PLANTARUM, Issue 4 2008Luciano Andrés Gabbarini The induction of root nodule development in actinorhizal symbiosis would depend on the concentration of factors produced by the bacteria and the plant. A detailed analysis of nodulation description parameters revealed different factors related to the nodulation process. The initial time for nodulation (t0), the initial nodulation rate (v0) and the total time of nodule development (tNOD) were defined and consequently quantified in different experimental conditions: co-inoculation of Discaria trinervis with increasing concentrations of different non-infective bacteria together with the full compatible infective Frankia strain (the indicator strain) used at a limiting concentration or by changing plant factor(s) concentration. All the above nodulation parameters were modified by changing doses of full compatibility infective strain Frankia BCU110501; v0 appears to be an expression of symbiotic recognition between partners as only fully symbiotic indicator Frankia BCU110501 was able to change it; t0 seems not to reflect symbiotic recognition because it can also be modified by non-infective Frankia but suggest the existence of a basic level of plant microbe recognition. The initial time for nodulation t0, reflecting the time required for the early interactions toward nodulation, is an inverse measure of the ability to establish early interactions toward nodulation. The increase in plant factors concentration also reduces t0 values, suggesting that a plant factor is involved and favors very early interactions. Increases in plant factors concentration also modify the final number of nodules per plant and the nodule cluster profile along the taproot as an expression of the autoregulation phenomenon. Meanwhile, Frankia inoculums' concentration, either infective or not, modified tNOD in an opposite way plant factors did. In conclusion, the analysis of nodulation kinetics appears to be an appropriate tool to investigate factors involved in the symbiotic interaction leading to the formation of nitrogen-fixing nodules. [source] Dual CD system-modified MEEKC method for the determination of clemastine and its impuritiesELECTROPHORESIS, Issue 19 2010Serena Orlandini Abstract A dual system of CDs was used for the first time in MEEKC with the aim of determining clemastine and its three main related impurities in both drug substances and tablets. The addition of methyl-,-cyclodextrin and heptakis(2,6-di- O -methyl)-,-cyclodextrin to the microemulsion pseudo-stationary phase was essential to increase the resolving power of the system to obtain a baseline separation among the compounds. The best microemulsion composition was identified by mixture design and the effects of the factors concentrations of CDs and voltage were investigated by a response surface study applying a Central Composite Design. In both cases, Derringer's desirability function made it possible to find the global optimum, which corresponded to the following combination: microemulsion, 89.8% 10,mM borate buffer pH 9.2, 1.5% n -heptane and 8.7% of SDS/n -butanol in 1:2 ratio; 18,mM methyl-,-cyclodextrin, 38,mM heptakis(2,6-di- O -methyl)-,-cyclodextrin, 17,kV. By applying these conditions, the separation was completed in about 5.5,min. The method was validated following International Conference on Harmonisation guidelines and was applied to a real sample of clemastine tablets. [source] The relationship of the level of circulating antiangiogenic factors to the clinical manifestations of preeclampsiaPRENATAL DIAGNOSIS, Issue 5 2009Young Nam Kim Abstract Objective This study investigated whether the antiangiogenic factors' concentrations differ according to the clinical manifestations of preeclampsia. Methods This study included 62 preeclampsia and compared the soluble fms-like tyrosine kinase-1 (sFlt-1), soluble endoglin (sEng), and placental growth factor (PlGF) concentrations among patients with different clinical manifestations of preeclampsia. We also compared the patients with preeclampsia to 62 controls matched by age, gestational age, and parity after 20 weeks of gestation. Results The sEng concentrations were significantly elevated in early-onset than in late-onset preeclampsia (105.4 ± 37.9 vs 66.3 ± 36.0 ng/mL, p = 0.0008). Moreover, the sEng levels were also higher in severe preeclampsia compared to mild (42.5 ± 31.0 vs 79.2 ± 38.6 ng/mL, p = 0.0013) and in the small for gestational age (SGA) group compared to the group without SGA (68.3 ± 39.3 vs 85.7 ± 38.2 ng/mL, p = 0.0273). The sFlt-1 levels, however, did not reveal significant difference according to the onset-time, severity, and presence of SGA. The antiangiogenic factors' concentrations were not related with the degree of hypertension or proteinuria. Conclusion Altered antiangiogenic factors might be involved in the pathogenesis of preeclampsia with synergistic, but different roles. Especially, sEng may be more related with early and severe preeclampsia. Copyright © 2009 John Wiley & Sons, Ltd. [source] | |||||||||||||