Effects Of Concentrations Research Articles

Effect of BA on Bud Grafting in Grapefruit

Experiments were conducted at Shambat Research Station,Agricultural Research Corporation, Khartoum North, to test the effect ofconcentrations and application methods of benzyladenine (BA), as a pre-budding treatment, on scion bud-break and shoot elongation of grapefruit(Citrus paradisi Macf. cv. “Redblush”). Nine- to twelve- months old sourorange (Citrus aurantium L.) seedlings were used as rootstock. Twoapplication methods of BA (foliar and soaking) were evaluated. Theresults showed that increasing BA concentration increased all parametersmeasured relative to the controls, irrespective of the application method.The highest percentage of bud-break, the largest number of leaves, thelongest scion shoots and the most growth rating values were obtainedwith soaking in 400 mg BA/litre treatment, compared with the control orthe lower or higher BA concentrations tested or plants treated with thefoliar application method. No significant differences were obtainedamong BA concentrations tested or application methods used on scionshoot length. However, soak application method gave high values for allparameters measured compared with the soak application method.Treatment duration had no effect on the efficiency of BA on bud break.

Cryptococcus albidus D24'ten Lipaz Üretimi Üzerindeki En Etkili Besin Maddelerinin Öneminin Belirlenmesi

In this study, the optimization of the medium components used for the production of lipase enzyme from Cryptococcus albidus D24 was performed using the Plackett-Burman statistical design method (PBD), and the most important nutrients affecting the production of lipase enzyme from D24 strain were determined as the first step. According to PBD, the highest lipase activity (19.34 U/ml/min) was obtained with medium including Tween 80 (X2) 2.5% (v/v), and (g/L) Peptone (X4) 8.0, Yeast Extract (X6) 7.5, Beef Extract (X7) 7.5, Malt Extract (X8) 7.5, NH4Cl (X9) 6.0, NaNO3 (X10) 1.5, (NH4)NO3 (X12) 6.0, (NH4)HCO3(X13) 6.0, MgSO4.7H2O (X15) 1.0, and KH2PO4 (X16) 2.0 at the end of 144 h cultivation. Regarding the concentration effect (CE) values obtained from PBD, NH4Cl (CE=7.1587), olive oil (CE=3.5544), (NH4)HCO3 (CE=3.0747), and tryptone (CE=2.1427) were evaluated as the more effective nutrients among the sixteen compounds studied. After that, the optimum concentrations of these effective compounds were experimented with Response Surface Methodology (RSM). Experimental results showed that the medium containing olive oil (X3) 1.5% (v/v), and (g/L) tryptone (X5) 3.0, NH4Cl (X9) 7.5, and (NH4)HCO3 (X13) yielded maximum lipase activity (12.03 U/ml/min) compared to other studied compounds. Although the maximum lipase activity obtained with RSM methodology was lower than that obtained by PBD, the cost of the nutrients used to produce one-unit enzyme is 0.104 Euro in the PBD, while only 0.0277 Euro is spent in RSM. In other words, the production of lipase using compounds coded X3, X5, X9, and X13 provides a cost-effective process.

Mechanical behavior of electrophoretically modified CFRP composites at elevated temperatures: An assessment of the influence of graphene carboxyl bath concentration

AbstractThe study aims at investigating the mechanical behavior of carbon fiber reinforced polymer (CFRP) composites modified with graphene carboxyl at elevated temperature (ET‐110°C) and understanding the effect of electrophoretic deposition bath concentration (0.5 g/L, 1.0 g/L, and 1.5 g/L) on their mechanical behavior at ET. The 1.5 g/L composite has revealed a maximum improvement in energy absorbed before failure of 33.25% at RT and 22.54% at ET for flexural testing and ∼35% at RT for short beam shear testing, over neat CFRP composite. The modified composites have shown an improved flexural strain to failure at both RT and ET, with 1.5 g/L composite exhibiting maximum enhancement of 12.41% at RT and 26.52% at ET over neat composite. However, at ET, modified composites exhibited lower flexural strength and interlaminar shear strength values in comparison to that of neat. Viscoelastic behavior of all composites was studied to understand bath concentration's effect on thermal behavior via dynamic mechanical thermal analysis. Differential scanning calorimetry was employed for governing the glass transition temperature of composites. Fractography of tested samples (both ET and RT) was performed utilizing a scanning electron microscope to determine the prominent failure mode.

EFEK FUNGISTATIS, FUNGISIDAL EKSTRAK KAYU MANIS TERHADAP CANDIDA ALBICANS DAN EFEK BAKTERISTATIS BAKTERISIDAL TERHADAP STAPHYLOCOCCUS AUREUS DARI DENTURE STOMATITIS

Cinnamon is one of the spices that has been used for a long time, even before 2100 BC as an essential material to mummify a king's body and also as addition for foods and drinks to increase the flavours. Cinnamon has three active components such as cinnamaldehyd, eugenol and linalool. Cinnamon has good fungicidal and fungistatic effect against Candida albicans and bacteristatic, bactericidal effect against Staphylococcus aureus. Cinnamon can be used to decrease the amount of Candida albicans and Staphylococcus aureus colonies, so the researcher is interested to examine the fungistatic, fungicidal, bacteristatic dan bactericidal effect against Candida albicans and Staphylococcus aureus. The goal of this research is to determine the effect of different concentrations of cinnamon extract against Candida albicans and Staphylococcus aureus.In this research, the extract's concentrations that are used are 100%, 50%, 25%, 12,5%, 6,25%, 3,125%, 1,56%, 0,78%, 0,39%, 0,195% and also two controls which are formaldehyd and aquadest. The extract used in this research is obtained by extraction method. Dilution technique is used in the test with three times replication. This research is experimental laboratorium type with pretest-postest design. Kruskal-Wallis and Mann-Whitney test is used to analyze the data.The result show that concentration 0,78 % extract has shown fungistatic effect and concentration 25% has shown fungicidal effect against Candida albicans, and concentration 1,562% bacteristatic, concentration 50% bactericidal Staphylococcus aureus. From double comparison table, we can conclude that there are significant difference between each concentration's effect against Candida albicans and Staphylococcus aureus.The result shows that the increase of cinnamon extract's concentration will lessen the remaining colonies of Candida albicans.

Method to Assess Interactivity of Drugs with Nonparallel Concentration‐Effect Relationships

Commonly used methods for analyzing interactivity between drugs (e.g., synergy, antagonism) such as isobologram, combination index, and curve shift are based on the Loewe Additivity principle of dose equivalence and the inherent assumption of similar concentration‐effect (C‐E) including parallel curves and equal maximum effects (Emax), and therefore are not suitable for drugs with dissimilar C‐E. This study describes a new method that is without this limitation and has the additional advantage of enabling statistical analysis. The method comprises two steps. First, based on the dose equivalence principle, the experimentally obtained C‐E of one drug was used to calculate the equally effective C‐E of the other drug at no interactivity; the resulting two zero‐interactivity C‐E formed the upper and lower boundaries of Additivity Envelope. Next, 95% confidence intervals calculated from experimental data were added to Additivity Envelope to obtain Uncertainty Envelope (UE). Experimentally observed effects of drug combinations (C‐Ecomb,observed) located within UE indicate additivity whereas C‐Ecomb,observed located above or below UE indicate statistically significant (p<0.05) synergy or antagonism, respectively. Additional in silico studies demonstrated the shape and size of Additivity Envelope, which determine the ability to detect drug interactivity, depended on the Drug A‐to‐B concentration ratios and the ratios of their C‐E curve shape parameter. Analyses of experimental results of combinations of drugs with nonparallel C‐E and/or unequal Emax indicate UE was more versatile and provided more information, compared to earlier methods. UE is a broadly applicable method for analysis, including statistical significance assessment, of drug interactivity.Support or Funding InformationThis research is supported in part by the National Institutes of Health, National Institute of General Medical Sciences [Grant R01GM100487]; and National Cancer Institute [Grant R01CA163015].

Inhibitory effect of RNA interference targeting human telomerase reverse transcriptase against hepatoblastoma cells

Objective To construct a recombinant retrovirus vector expressing small interfering RNA (siRNA) targeting human telomerase reverse transcriptase (hTERT), and assess its effect on proliferation and apoptosis of human hepatoblastoma cells. Methods The sequences of the siRNA targeting hTERT, U6 promoter and enhanced green fluorescent protein (EGFP) gene were amplified by polymerase chain reaction (PCR) and inserted into the mammalian retroviral expression vector pLXSN. The PCR method was used to amplify hTERT-siRNA, EGFP, DNA fragment of U6+ 27. The retroviral expression vector pLXSN-EGFP-U6-siTERT was constructed and subjected to enzyme digestion identification. The recombinant retroviral vector pLXSN-EGFP-U6-siTERT was constructed. The vector was then used to infect human hepatoblastoma cell HepG2. The telomerase activity of the infected cells was detected by telomerase repeat amplification protocol-silver staining, and the cell apoptosis was examined using flow cytometry. The inhibition rate of HepG2 cell proliferation was analyzed by methyl thiazol tetrazolium (MTT) assay. Results hTERT-siRNA retroviral expression vectors were successfully prepared. In the control group, the telomerase activity was 2 143.06±198.69. At 24, 48 and 72 h after colony forming units (CFU) recombinant virus infection the telomerase activity was 1 632.02±116.28, 899.38±126.11 and 321.25±25.25 respectively. As compared with before infection, the telomerase activity was respectively decreased by 23.84%, 58.03% and 85.01%. There was significant difference among different time groups (P=0.046, 0.024 and 0.008). The results of flow cytometry showed that there was significant difference in the cell apoptosis rate between the experimental group and the control group with different titer of recombinant virus infection, and there was a concentration-dependent relationship. At 24 h after 1×105 CFU recombinant virus infection, the apoptosis rate was 29.05%. MTT results showed that apoptosis rate was 29.05% at 24 h after recombinant virus infection, the tumor cell death was significant, and with the increase in virus titer and prolongation of time, cell death also gradually increased. At 24, 48 and 72 h after virus infection of 6.0×105 CFU, the results of MTT assay were 0.29±0.14, 0.20±0.13 and 0.18±0.11 respectively. At 24, 48 and 72 h after virus infection of 3.0×105 CFU, MTT results were 0.32±0.11, 0.26±0.12 and 0.25±0.10. At 24, 48 and 72 h after virus infection of 1.0×105 CFU, results of MTT assay were 0.33±0.12, 0.26±0.13 and 0.26±0.12. At 24, 48 and 72 h after virus infection of 1.0×104 CFU, the results of MTT assay were 0.43±0.14, 0.35±0.10 and 0.33±0.15. At 24, 48 and 72 h after virus infection of 1.0×103 CFU, the results of MTT assay were 0.52±0.11, 0.44±0.13 and 0.44±0.10. At 24, 48 and 72 h after virus infection of 1.0×102 CFU, the results of MTT assay were 0.65±0.13, 0.61±0.15 and 0.60±0.16. In the negative control group, the results of MTT assay were 0.69±0.11, 1.01±0.14 and 2.98±0.16 respectively at 24, 48 and 72 h. There existed the concentration-effect and time-effect relationship (P=0.037, 0.034 and 0.028). Conclusion hTERT-siRNA can effectively silence hTERT gene and suppress the telomerase activity and proliferation of HepG2 cells. Key words: RNA interference; Human telomerase reverse transcriptase; Hepatoblastoma; Apoptosis

Structural and optical properties of strontium/copper co-doped lithium borate glass system

There is continuous search for materials having superior optical and structural properties in glass photonics, thermoluminescence dosimetry and phosphors fields. A new series of copper (Cu)/strontium (Sr) co-doped lithium borate glasses (LB:Sr, Cu) of composition (85−x)H3BO3–15Li2CO3–2SrCO3–xCu2O, where x=0.005 to 0.1mol% were prepared using melt quenching method. Synthesized glasses are characterized to determine the concentration's effect of copper ions (Cu2+) on modification of the structural and optical properties. XRD patterns confirmed the amorphous nature and FESEM verified the homogeneous surface morphology. EDX spectra authenticated the accurate elemental traces. Glasses are thermally stable with Hurby parameter ~0.5. Glass density decreases with the increasing Cu2+ concentration. FTIR peaks in the range of 698–1070cm−1 attribute to trigonal and tetrahedral stretching vibrations of BO3 and BO4 units. The direct/indirect band gap and Urbach energy vary from 3.1–2.8eV/2.94–2.84eV and 1.2–2.18eV, respectively. The observed increase in refractive index ascribed to the conversion of BO4 into BO3 units. PL spectra under 280nm excitations display two peaks centered at 482 and 526nm accompanied by slight peak shift towards the lower wavelength. Excellent structural and spectroscopic characteristics of the present glass compositions indicate prospects for various photonic devices.

Abstract 3485: Uncertainty envelope to evaluate drug interactivity with statistical analysis

Abstract Introduction. Development of new therapies for cancer and infections frequently involves combinations of two or more drugs. Existing methods to quantify drug interactivity are suitable for analyzing drugs with parallel concentration-effect curves and similar maximum drug effects. This study established a method for the remaining situations. Methods. Equations describing zero-interactivity effects of combination therapy were developed based on the principle that a drug cannot interact with itself (i.e., additivity only). These equations were used to convert the concentration-effect (C-E) curve of the combination to C-E curve for each of the two drugs in the combination as if they were used as single agents (single agent-equivalent curves). Confidence intervals (CI) of these curves were generated using the error propagation method. Effect data of drug combinations were analyzed by the new and existing methods. Results. The calculated single agent-equivalent curves plus 95% CI defined the boundaries of an envelope for additive drug effects (Uncertainty Envelope). The Envelope shape and size were determined by differences in the shapes of single agent C-E curves. The nature of drug interactivity is indicated by the location of experimental data points of the combination; data points located within the Envelope indicate additivity, whereas points above and below the Envelope respectively indicate statistically significant synergy and antagonism. In comparison with the existing methods, the Envelope method yielded more conservative results (additivity vs. synergy or antagonism). Conclusion. Uncertainty Envelope method enables the interactivity analysis between drugs with nonparallel C-E curves and unequal maximal effect, with statistical confidence. Citation Format: Liang Zhao, Jessie L.-s. Au, M. Guill Wientjes. Uncertainty envelope to evaluate drug interactivity with statistical analysis. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3485. doi:10.1158/1538-7445.AM2015-3485

Why does necking ignore notches in dynamic tension?

Recent experimental work has revealed that notched tensile specimens, subjected to dynamic loading, may fail by growing a neck outside of the notched region. This apparent lack of sensitivity to a classical stress concentration case was reported but not explained or modeled.The present paper combines experimental and numerical work to address this issue. Specifically, it is shown that the dynamic tensile failure locus is dictated by both the applied velocity boundary condition and the material mechanical properties, specifically strain-rate sensitivity and strain-rate hardening.It is shown that at sufficiently high impact velocities, the flows stress in the notch vicinity becomes quite higher than in the rest of the specimen, so that while the former resists deformation, it transfers the load to the latter. The result will be the formation of a local neck and failure away from the notch.This effect is shown to be active when the material properties are perturbed only at the local level, as in the case of machining of the notch, which in itself may again be sufficient to stabilize the structure under local failure until a neck forms elsewhere.While the physical observations are quite counterintuitive with respect to the engineering views of stress concentrator's effect, the present work rationalizes those observations and also provides information for the designers of dynamically tensioned structures that may contain notches or similar flaws.

Why does necking ignore notches in dynamic tension?

Recent experimental work has revealed that necking of tensile specimens, subjected to dynamic loading, is a deterministic phenomenon, governed by the applied boundary conditions. Furthermore it was shown that the potential sited, dictated by the boundary conditions, may prevail even in the presence of a notch, thus necking may occur away of the notched region. The present paper combines experimental and numerical work to address this issue. Specifically, it is shown that the dynamic tensile failure locus is dictated by both the applied velocity boundary condition and the material mechanical properties, specifically strain-rate sensitivity and strain-rate hardening. It is shown that at sufficiently high impact velocities, the flows stress in the notch vicinity becomes quite higher than in the rest of the specimen, so that while the former resists deformation, it transfers the load to the latter, resulting in the formation of a local neck and failure away from the notch. Small local perturbations in the material properties are shown to be sufficient to stabilize the structure under local failure until a neck forms elsewhere. While the physical observations are quite counterintuitive with respect to the engineering views of stress concentrator's effect, the present work rationalizes those observations and also provides information for the designers of dynamically tensioned structures that may contain notches or similar flaws.

The Power of Phase I Studies to Detect Clinical Relevant QTc Prolongation: A Resampling Simulation Study

Concentration-effect (CE) models applied to early clinical QT data from healthy subjects are described in the latest E14 Q&A document as promising analysis to characterise QTc prolongation. The challenges faced if one attempts to replace a TQT study by thorough ECG assessments in Phase I based on CE models are the assurance to obtain sufficient power and the establishment of a substitute for the positive control to show assay sensitivity providing protection against false negatives. To demonstrate that CE models in small studies can reliably predict the absence of an effect on QTc, we investigated the role of some key design features in the power of the analysis. Specifically, the form of the CE model, inclusion of subjects on placebo, and sparse sampling on the performance and power of this analysis were investigated. In this study, the simulations conducted by subsampling subjects from 3 different TQT studies showed that CE model with a treatment effect can be used to exclude small QTc effects. The number of placebo subjects was also shown to increase the power to detect an inactive drug preventing false positives while an effect can be underestimated if time points around t max are missed.

Comparative characteristics of Lupinus albus L. and Lupinus luteus L. under allelopathic effect of Sorghum halepense L. (Pers.)

Allelopathic effects of aqueous extracts of Sorghum halepense L. (Pers.) on seed germination and primary seedling growth and development of two lupine species was studied. Lupinus albus and Lupinus luteus showed different levels of susceptibility to the allelopathic effect of weed extracts. Increasing concentrations (1.25, 2.50, 5.00 and 10.00%) of extracts from aboveground and belowground biomass suppressed seed germination of L. luteus from 53.2 to 74.7%. The germination of L. albus seeds was unaffected, except by the highest concentration of 10.00%. Fresh biomass accumulation in the initial germ of L. luteus was inhibited by 3.8-40.3% under the effect of concentrations of 2.50, 5.00 and 10.00%, which made the species susceptible to S. halepense extracts. L. albus was tolerant as it was not found to sustain a significant allelopathic effect of the extracts.

Effects of sevoflurane and isoflurane on blockade of adult type nicotinic acetylcholine receptors of skeletal muscle of rats by rocuronium

Objective To investigate the effects of sevotlurane and isoflurane on blockade of adult nicotinic acetylcholine receptor (e-nAChR) of skeletal muscle of rats by rocuronium.Methods HEK293 cell line was provided by Molecular Biology Laboratory,Chonqing Medical University and cultured in DMEM liquid culture medium containing 10％ bovine calf serum at 37 ℃in incubator filled with 5％ CO2.e-nAChR was expressed heterologously in HEK293 cell using liposome transfection technology.The whole cell patch clamp technology was used to establish the concentration-effect curves for inhibition of acetylcholine (ACh)-induced current.The 5％ inhibitory concentration values ( IC5 ),25 ％ inhibitory concentration values ( IC25 ) and 50％ inhibitory concentration values (IC50) for sevoflurane,isoflurane and rocuronium were calculated.Firstly the inhibitory effect of rocuronium at a concentration of IC25 was studied in the presence of sevoflurane and isoflurane at concentrations of IC5,IC25 and IC50.Subsequently the inhibitory effect of rocuronium at concentrations of IC5,IC25 and IC50 was studied in the presence of sevoflurane and isoflurane at a concentration of IC25.Inhibition of ACh-induced current amplitude was recorded.Results At the concentrations of IC5,IC25 and IC50 sevoflurane or isoflurane had synergistical inhibitory effect on the current amplitude of e-nAChR with rocuronium at the concentrations of IC5 and IC25,while had addition inhibitory effect on the current amplitude of e-nAChR with rocuronium at the concentration of IC50.The inhibitory effect of sevoflurane at the concentration of IC5 on the current amplitude of e-nAChR with rocuronium at the concentration of IC25 was weaker than that of isoflurane,while the inhibitory effect of sevoflurane at the concentration of IC50 on the current amplitude of e-nAChR with rocuronium at the concentration of IC25 was stronger than that of isoflurane.The inhibitory effect of sevoflurane at the concentration of IC25 on the current amplitude of e-nAChR with rocuronium at the concentration of IC5 was weaker than that of isoflurane.Conclusion Either sevoflurane or isoflurane has synergistical blocking effect on e-nAChR with low concentration of rocuronium,while has addition blocking effect with high concentration of rocuronium.Potentiation of blocking effect of rocuronium on e-nAChR by low concentration of sevoflurane is weaker than that by isoflurane,while the potentiation by sevoflurane at high concentration is stronger than that by isoflurane. Key words: Isoflurane; Androstanols; Receptors, nicotinic; Muscle, skeletal; Sevoflurane

Premature abscission of phaseolus bean pods: The role of plant growth substances

A 2x5 factorial experiment was conducted to study the effect of concentrations of 6-benzyladenine (BA) applied at five post anthesis stages on pod development of Phaseolus vulgaris L., especially in relation to abscission. The terminal raceme of a five-node cultivar (cv 344) was used for the study. There were no significant differences between treated plants and controls with respect to numbers of flowers that opened and those that developed into pods. BA not only delayed the onset of pod abscission but also slowed it down, giving it a protracted duration. The cytokinin was effective in reducing pod abscission when application commenced between anthesis and six days after anthesis. BA affected pod retention on the distal triad of the terminal raceme where normally all pods drop off. All treated racemes had significantly (P <0.01) more seeds at the time of harvest than controls, the overall increase in seed number being due to increased seed number in pods borne on the medial and distal triads of the raceme. BA increased pod retention and seed yield without any significantly effect on the number of pods on other nodes, and dry matter of the stem and leaves. When BA was applied beginning at the time of anthesis and using the higher dosage (400 ppm), normally abscising fruits on the distal triad were retained with full seed development.

Population Pharmacodynamic Parameter Estimation from Sparse Sampling: Effect of Sigmoidicity on Parameter Estimates

The objective of this stimulation study was to evaluate effect of simoidicity of the concentration-effect (C-E) relationship on the efficiency of population parameter estimation from sparse sampling and is a continuation of previous work that addressed the effect of sample size and number of samples on parameters estimation from sparse sampling for drugs with C-E relationship characterized by high sigmoidicity (gamma > 5). The findings are based on observed C-E relationships for two drugs, octreotide and remifentanil, characterized by simple E (max) and sigmoid E (max) models (gamma = ~2.5), respectively. For each model, C-E profiles (100 replicates of 100 subjects each) were simulated for several sampling designs, with four or five samples/individual randomly obtained from within sampling windows based on EC(50)-normalized plasma drug concentrations, PD parameters based on observed population mean values, and inter-individual and residual variability of 30% and 25%, respectively. The C-E profiles were fitted using non-linear mixed effect modeling with the first-order conditional estimation method; variability parameters were described by an exponential error model. The results showed that, for the sigmoid E (max) model, designs with four or five samples reliably estimated the PD parameters (EC(50), E (max), E (0), and gamma), whereas the five-sample design, with two samples in the 2-3 E (max) region, provided in addition more reliable estimates of inter-individual variability; increasing the information content of the EC(50) region was not critical as long as this region was covered by a single sample in the 0.5-1.5 EC(50) window. For the simple E (max) model, because of the shallower profile, enriching the EC(50) region was more important. The impact of enrichment of appropriate regions for the two models can be explained based on the shape (sigmoidicity) of the concentration-effect relationships, with shallower C-E profiles requiring data enrichment in the EC(50) region and steeper curves less so; in both cases, the E (max) region needs to be adequately delineated, however. The results provide a general framework for population parameter estimation from sparse sampling in clinical trials when the underlying C-E profiles have different degrees of sigmoidicity.

Effects of stanozolol on collagen synthesization of cultured growth plate chondrocytes from pubertal female rat treated with GnRHa in vitro

Objective To observe the effects of stanozolol on collagen I1 and X synthesization of cul- tured growth plate ehondrocytes from pubertal female rat treated with GnRHa in vitro. Methods Primary Chon-drocytes from 6 female rats were divided into two groups ( time-effect groups and concentration-effect groups). immunohistochemical staining of collagen Ⅱ, X were conducted. Results the results of type Ⅱ collagen synthe- sization demonstrated stanozolol enhanced the proliferation of the chondrocytes, time-course studies had shown that the proliferation were maximally stimulated by stanozolol after 3 days of incubation and decreased again after longer periods of incubation. Stanozolol did not stimulated type X collagen synthesization from 10-11 M-10-8 M, but experiments showed that type X collagen was already stimulated after incubation in stanozolol (10-7-10-5 M). Time-course studies had shown those type X collagen synthesizations were stimulated by stanozolol after 4-5 days of incubation. Conclusion Stanozoiol enhances the proliferation of ehondrocytes of pubertal female rat treated with GnRHa in vitro( time-course-dependent and concentration-dependent). Key words: Chondrocyte; Epiphyseal growth plate; Stanozolol; Collagen

Fracture performance of clay/epoxy nanocomposites with clay surface-modified using 3-aminopropyltriethoxysilane

It is known that the mechanical properties of clay-reinforced nanocomposites are significantly affected by the dispersion of clay particles in the matrix. This study investigated the clay concentration's effect on the fracture behavior of surface-modified MMT/epoxy nanocomposites. For this purpose, fracture tests were performed using samples with four different clay concentration levels. After the fracture tests, scanning electron microscopy analysis was performed on the fracture surfaces to examine the fracture mechanism depending on the clay concentration level. The analysis found that MMT modification using 3-aminopropyltriethoxysilane produces good dispersion of MMT in the epoxy and increases the intercalation effect. Fracture toughness decreased up to 4wt% of MMT and increased at 6wt%, followed by another decrease at 10wt%. This occurs due to the nanocomposite's increased brittleness and increased debondings between MMT and epoxy, as well as voids.

Graded α-adrenoceptor activation of arteries involves recruitment of smooth muscle cells to produce ‘all or none’ Ca2+signals

Confocal laser scanning microscopy and Fluo-4 were used to visualize Ca2+transients within individual smooth muscle cells (SMC) of rat resistance arteries during α1-adrenoceptor activation. The typical spatio-temporal pattern of [Ca2+] in an artery after exposure to a maximally effective concentration of phenylephrine (PE, 10.0μM) was a large, brief, relatively homogeneous Ca2+transient, followed by Ca2+waves, which then declined in frequency over the course of 5min and which were asynchronous in different SMC. Concentration–Effect (CE) curves relating the concentration of PE (range: 0.1μM to 10.0μM) to the effects (fraction of cells producing at least one Ca2+wave, and number of Ca2+waves during 5min) had EC50values of ∼0.5μM and ∼1.0μM respectively. The initial Ca2+transient and the subsequent Ca2+waves were abolished in the presence of caffeine (10.0μM). A repeated exposure to PE, 1.5min after the first had ended, elicited fewer Ca2+waves in fewer cells than did the initial exposure. Caffeine-sensitive Ca2+stores were not depleted at this time, however, as caffeine alone was capable of inducing a large release of Ca2+1.5min after PE. In summary, the mechanism of a graded response to graded α1-adrenoceptor activation is the progressive ‘recruitment’ of individual SMC, which then respond in ‘all or none’ fashion (viz. asynchronous Ca2+waves). Ca2+signaling continues in the arterial wall throughout the time-course (at least 5min) of activation of α1-adrenoceptors. The fact that the Ca2+waves are asynchronous accounts for the previously reported fall in 'arterial wall [Ca2+]' (i.e. spatial average [Ca2+] over all cells).

Interactions among Localized Corrosion Sites Investigated with Electrode Arrays

Interactions among local pit sites were investigated using an array of 25 electrodes. The 5 x 5 array consisted of closely spaced, flush-mounted 316 stainless steel wires polarized in 0.05 M NaCl solution. Two types of interactions occurred when either singl e or rows of actively corroding pits existed while the remaining electrodes were initially passive. Inhibition of pitting on near by electrodes occurred due to ohmic potential drop near active pre-existing pits. Enhancement of pitting was observed due to alteratio ns in the local solution composition near just deactivated pits. The former effect was stronger than the latter, but the concentrat ion effect could persist after pit deactivation.

Pharmacokinetics and concentration-effect relationship after propofol infusion.

We investigated the pharmacokinetics (PK) and concentration-effect relationship after an infusion of propofol in order to obtain a model which can predict the time to eye opening. Anaesthesia was induced and maintained with propofol in 34 patients using a Computer Controlled Infusion Pump. Arterial blood samples were taken during recovery and a new model describing the PK was derived. The model was then used to predict the concentration of propofol at the time of eye opening to command. The central volume of distribution was 0.228 L/kg, and the inter-compartment transfer rate constants (min-1) were: k10 0.166, K12 0.091, k13 0.124, k21 0.045, and k31 0.0098. The predicted concentration at which 50% of the patients responded to command was 0.98 microgram/ml. PK parameters predicting propofol concentration during anaesthesia differ from those describing recovery. The PK of propofol during recovery following an infusion are similar to those following a bolus dose. Real time estimation of blood propofol concentration serves as a useful additional monitor of recovery from anaesthesia.