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101.
102.
103.
Transpiration rate, leaf area, the content of nitrogen and saccharides decreased with the decrease in soil moisture content
from 90 % to 30 % of full field capacity. Stomatal frequency, fresh and dry matter and the chlorophyll and carotenoid contents
of lupine or safflower remained more or less unaffected. After spraying with the antitranspirant (PMA) the saccharide contents
were raised. As concern the lipids content and the contents of Ca, Mg and P, treated plants exhibited variable response to
both drought stress and spraying with various PMA concentrations. 相似文献
104.
The solubilizing and absorption enhancer properties towards nimesulide (ND) of tromethamine (Tris) and polyvinylpyrrolidone
(PVP) have been investigated. Solid binary systems were prepared at various drug-polymer ratios by mixing or coprecipitation,
characterized by differential scanning calorimetry, X-ray diffractometry, and Fourier transform infrared spectroscopy, and
tested for dissolution behavior. Both carriers improved drug dissolution and their performance depended on concentration of
the hydrophilic carrier in coprecipitates. Tris was more effective than PVP, despite the amorphizing power of PVP as revealed
by solid state analyses. Complete drug amorphiztion was attained at 1∶3 (wt/wt) drug: PVP, 25% (wt/wt) ND in PVP. According
to thermal behavior of ND and Tris, ND-Tris systems present a eutectic behavior. The eutectic composition was 30% ND-70% Tris
at ∼129°C. Amorphous ND-PVP and eutectic ND-Tris mixtures showed an improvement of 5.55 and 6.6 times of drug dissolution
efficiency, respectively. In vivo experiments in mice demonstrated that administration of 60 mg/kg of drug coprecipitated
with PVP or Tris resulted, respectively, in a 50% and 94% reduction of acetic acid-induced writhings in comparison with pure
drug, which, instead, was statistically ineffective as compared with the control group. Moreover, the eutectic mixture of
ND-Tris demonstrated antiwrithing potency 1.88 times higher than amorphous ND-PVP coprecipitate. Thus, the solubilizing power,
dissolution-enhancing effect, and analgesic effect enhancer ability toward the drug make Tris particularly suitable for developing
a reduced-dose, fast-release solid oral dosage form of nimesulide.
Published: August 10, 2007 相似文献
105.
El Ashry el SH Abdel-Rahman A Rashed N Awad LF Rasheed HA 《Nucleosides, nucleotides & nucleic acids》2006,25(3):299-305
Nucleophilic displacement of the tosyloxy group in 7-(2-hydroxy-3-p-toluenesulfonyloxypropyl)theophylline (1) with azide anion afforded 7-(3-azido-2-hydroxypropyl)theophylline (2). Reduction of the 3-azido group in 2 with Ph3P/Py/NH4OH afforded the 3-amino derivative 4, alternatively obtained by regioselective amination of 7-(2,3-epoxypropyl)theophylline (3). Selective acetylation of 4 gave the N-acetyl derivative 5. 1,3-Dipolar cycloaddition of the azide group in 2 with N1-propargyl thymine (6) afforded the regioisomeric triazole 7. 相似文献
106.
107.
Elnakish MT Awad MM Hassona MD Alhaj MA Kulkarni A Citro LA Sayyid M Abouelnaga ZA El-Sayed O Kuppusamy P Moldovan L Khan M Hassanain HH 《American journal of physiology. Heart and circulatory physiology》2011,301(3):H868-H880
Rac1-GTPase activation plays a key role in the development and progression of cardiac remodeling. Therefore, we engineered a transgenic mouse model by overexpressing cDNA of a constitutively active form of Zea maize Rac gene (ZmRacD) specifically in the hearts of FVB/N mice. Echocardiography and MRI analyses showed cardiac hypertrophy in old transgenic mice, as evidenced by increased left ventricular (LV) mass and LV mass-to-body weight ratio, which are associated with relative ventricular chamber dilation and systolic dysfunction. LV hypertrophy in the hearts of old transgenic mice was further confirmed by an increased heart weight-to-body weight ratio and histopathology analysis. The cardiac remodeling in old transgenic mice was coupled with increased myocardial Rac-GTPase activity (372%) and ROS production (462%). There were also increases in α(1)-integrin (224%) and β(1)-integrin (240%) expression. This led to the activation of hypertrophic signaling pathways, e.g., ERK1/2 (295%) and JNK (223%). Pravastatin treatment led to inhibition of Rac-GTPase activity and integrin signaling. Interestingly, activation of ZmRacD expression with thyroxin led to cardiac dilation and systolic dysfunction in adult transgenic mice within 2 wk. In conclusion, this is the first study to show the conservation of Rho/Rac proteins between plant and animal kingdoms in vivo. Additionally, ZmRacD is a novel transgenic model that gradually develops a cardiac phenotype with aging. Furthermore, the shift from cardiac hypertrophy to dilated hearts via thyroxin treatment will provide us with an excellent system to study the temporal changes in cardiac signaling from adaptive to maladaptive hypertrophy and heart failure. 相似文献
108.
Hamdy AA 《Current microbiology》2000,41(4):239-245
New biosorbent material derived from ubiquitous marine algae has been examined in packed-bed flow for Pb2+ removal through sorption columns. Mixed biomass of marine algae has been used, consisting of representative species of the
following algae: Ulva lactuca (green algae), Jania rubens (red algae), and Sargassum asperifolium (brown algae). A mixture of these three species showed a promising removal capacity for Pb2+ from aqueous solution. Lead uptake up to 281.8 mg/g dry algal mixture was observed. Equilibrium was achieved after 120 min.
No significant effect of changing the flow rate on the removal capacity was noticed. It was found that Langmuir model expresses
the system at pH 4. Mineral acids exhibited good elution properties (a mean of 93%) for recovery of sorbed biomass ions as
compared with the tested alkalies (about 60%).
Received: 21 December 1999 / Accepted: 24 April 2000 相似文献
109.
Mohamed S. Abdel-Rahman Duck H. Suh Abdelrazak M. Kadry Gloria A. Skowronski 《人类与生态风险评估》1999,5(5):985-996
Risk assessors routinely use the reference dose (RfD) approach for non-cancer risk assessment. In this approach, No-Observed-Adverse-Effect-Level (NOAEL) is divided by the product of uncertainty factors (UFs) and, occasionally, an additional modifying factor (MF), each usually employed by default as factors of 10. In the present investigation, kinetic and dynamic data have been used in order to reduce uncertainties when establishing exposure guidelines for examples of chemicals representing four classes of pesticides (warfarin, lindane, carbaryl and parathion). An intensive search of databases was conducted for these pesticides, and toxicokinetic and toxicodynamic parameters in inter- and intra-species were evaluated. The kinetic and dynamic subfactors were less than the proposed values of Renwick and the International Programme on Chemical Safety (IPCS). The composite factors for all the examined pesticides were less than 100. The present study indicated that in setting exposure levels it is important to incorporate kinetic and dynamic data, as they become available, rather than rely on default uncertainty factors, which are imprecise in many cases. 相似文献
110.
Fraser C Rothwell J Power M Hobson A Thompson D Hamdy S 《American journal of physiology. Gastrointestinal and liver physiology》2003,285(1):G137-G144
We investigated the effects of water swallowing, pharyngeal stimulation, and oropharyngeal anesthesia on corticobulbar and craniobulbar projections to human swallowing musculature. Changes in pathway excitability were measured via electromyography from swallowed intraluminal pharyngeal and esophageal electrodes to motor cerebral and trigeminal nerve magnetic stimulation. After both water swallowing and pharyngeal stimulation, pharyngoesophageal corticobulbar excitability increased (swallowing: pharynx = 59 +/- 12%, P < 0.001; esophagus = 45 +/- 20%, P < 0.05; pharyngeal stimulation: pharynx = 76 +/- 19%, P < 0.001; esophagus = 45 +/- 23%, P = 0.05), being early with swallowing but late with stimulation. By comparison, craniobulbar excitability increased early after swallowing but remained unaffected by pharyngeal stimulation. After anesthesia, both corticobulbar (pharynx =-24 +/- 10%, P < 0.05; esophagus = -28 +/- 7%, P < 0.01) and craniobulbar excitability showed a late decrease. Thus swallowing induces transient early facilitation of corticobulbar and craniobulbar projections, whereas electrical stimulation promotes delayed facilitation mainly in cortex. With removal of input, both corticobulbar and craniobulbar projections show delayed inhibition, implying a reduction in motoneuron and/or cortical activity. 相似文献