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1.
Natural wetlands play an important role in the global carbon cycle, and loss of dissolved carbon through water has been indicated as one of the most important carbon sources for riverine ecosystems. During the last century, a large natural wetland area was reported to be converted to other land use types such as rice paddy land around the world. In this study, we explored the dynamics of dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) in two natural freshwater wetlands and a rice paddy field, which was reclaimed from the natural wetlands in the Sanjiang Plain, Northeastern China, during the growing season (May–October) of 2009. The DOC and DIC concentrations in the two ecosystems were significantly different (P < 0.05). The mean DOC concentrations during the growing season in the surface water of the Deyeuxia angustifolia and Carex lasiocarpa wetlands were 49.88 ± 5.44 and 27.97 ± 1.69 mg/L, respectively, while it was only 8.63 ± 2.54 mg/L in the rice paddy field. Specific ultra-violet light absorption at 254 nm (SUVA254) of DOC increased by an average of 19.54% in the surface water from the natural wetlands to rice paddy, suggesting that DOC mobilized in the natural wetlands was more aromatic than that in the rice paddy field. The mean DIC concentration in surface water of the rice paddy was 5.25 and 5.04 times higher than that in the natural D. angustifolia and C. lasiocarpa wetlands, respectively. The average ratio of DIC to dissolved total carbon (DTC) for the water sampled from the artificial drainage ditch in the rice paddy field was 61.82%, while it was 14.75% from the nearby channel of natural wetlands. The significant differences in dissolved carbon concentration in surface water and channels originating from different land use types suggested that reclamation of natural wetlands to rice paddy field would reduce DOC runoff and increase the DIC concentration to adjacent watersheds. Our study results for the changed pattern in dissolved carbon after the natural wetland was transformed to paddy field could have important implications for studying the impacts of the large-scale land use change to carbon cycle and management.  相似文献   

2.
The aim of this study was to assess H-reflex plasticity and activation pattern of the plantar flexors during a sustained contraction where voluntary EMG activity was controlled via an EMG biofeedback. Twelve healthy males (28.0 ± 4.8 yr) performed a sustained isometric plantar flexion while instructed to maintain summed EMG root mean square (RMS) of gastrocnemius lateralis (GL) and gastrocnemius medialis (GM) muscles fixed at a target corresponding to 80% maximal voluntary contraction torque via an EMG biofeedback. Transcutaneous electrical stimulation of the posterior tibial nerve was evoked during the contraction to obtain the maximal H-reflex amplitude to maximal M-wave amplitude ratio (Hsup/Msup ratio) from GL, GM and soleus (SOL) muscles. Neuromuscular function was also assessed before and immediately after exercise. Results showed a decrease in SOL activation during sustained flexion (from 65.5 ± 6.4% to 42.3 ± 3.8% maximal EMG, p < 0.001), whereas summed EMG RMS of GL and GM remained constant (59.7 ± 4.8% of maximal EMG on average). No significant change in the Hsup/Msup ratio was found for SOL, GL and GM muscles. Furthermore, it appears that the decrease in maximal voluntary contraction torque (?20.4 ± 2.9%, p < 0.001) was related to both neural and contractile impairment. Overall, these findings indicate that the balance between excitation and inhibition affecting the motoneuron pool remains constant during a sustained contraction where myoelectrical activity is controlled via an EMG biofeedback or let free to vary.  相似文献   

3.
4.
The effects of ammonium in a chemically defined maturation medium on oocyte nuclear maturation and subsequent embryonic development of pigs after in vitro fertilization (IVF) and parthenogenetic activation (PA) were examined. Cumulus–oocyte complexes were matured in Purdue Porcine Medium (PPM) supplemented with 0 mM, 0.02 mM, 0.2 mM, 2 mM, or 20 mM ammonium chloride, or TCM199 with 10% porcine follicle fluid (TCM + pFF; positive control) at 38.7 °C in 7% CO2 in air for 40–44 h. No significant difference (P > 0.05) in nuclear maturation was found between oocytes matured in TCM + pFF or PPM with 0 mM, 0.02 mM and 0.2 mM ammonium chloride. However, nuclear maturation was decreased (P < 0.05) in oocytes matured in PPM with 2 mM or 20 mM ammonium. After IVF, oocytes matured in PPM with 20 mM ammonium resulted in embryos with reduced (P < 0.05) embryonic cleavage and blastocyst development than all other treatment groups. After PA, oocytes matured in PPM with 20 mM ammonium resulted in embryos with lesser (P < 0.05) embryonic cleavage compared to TCM + pFF. However, PA embryos derived from oocytes matured in PPM with both 2 mM and 20 mM ammonium had reduced (P < 0.05) blastocyst development compared with TCM + pFF. These results demonstrate the detrimental effect of ammonium during in vitro oocyte maturation on nuclear progression to metaphase II. Additionally, the presence of ammonium during in vitro maturation negatively influences subsequent embryonic development, although PA embryos appear to be more sensitive to the negative effects of ammonium during oocyte maturation than do IVF embryos.  相似文献   

5.
《Theriogenology》2009,71(9):1560-1568
The objectives of this study were to assess the effects of induced testicular degeneration in Bos taurus indicus (Nellore) bulls on changes in seminal characteristics and fertilizing ability of sperm. Four Nellore bulls (30–36-month-old, 500–550 kg) with good seminal quality (>80% motile and morphologically normal sperm) had scrotal insulation applied for 5 d. Semen was collected by electroejaculation and cryopreserved at the pre-insulation moment, and 7, 14, and 21 d after insulation was removed. Gross motility, vigor of sperm movement (1–5), acrosome integrity, sperm morphology (phase-contrast microscopy), nuclear vacuoles and abnormal chromatin (Feulgen-stain) were determined after sperm preparations for in vitro fertilization (IVF). Prior to IVF, sperm were separated using a Percoll gradient (45% and 90%). Normal sperm decreased (P < 0.05) 14 and 21 d after insulation was removed. On 14 and 21 d, the incidence of head defects (9.7 ± 0.6 and 17.0 ± 0.8, respectively; mean ± S.E.M.) was higher (P < 0.05) in agreement with the incidence of nuclear vacuoles (14.0 ± 5.0 and 12.3 ± 2.3) and abnormal chromatin (24.4 ± 7.2 and 30.8 ± 2.8). Although the frequency of cleaved oocytes decreased only on 21 d (P < 0.05), blastocyst rates were lower (P < 0.05) than pre-insulation on 14 and 21 d. In regression analyses, only nuclear vacuoles, head defects and intact acrosome accounted for differences in cleavage (R2 = 0.38, 0.48, and 0.30, respectively) and blastocyst rates (R2 = 0.35, 0.37, and 0.44). Abnormal chromatin was associated only with blastocyst rates (R2 = 0.35). In conclusion, blastocyst rate was more sensitive than cleavage rate and the assessment of nuclear integrity is recommended to predict the fertilizing ability of bull sperm.  相似文献   

6.
It is unknown if females and males use jaw muscles similarly during exercise. This pilot study assessed jaw elevator muscle duty factors (DFs = time of muscle activity/total recording time) at repeated sessions to test if DFs are reliable and different between sexes during exercises in two environments. Ten female and seven male subjects recruited from university soccer teams provided informed consent. Surface electromyography was recorded from masseter and temporalis muscles during biting and leg-extension laboratory exercises. Average activities to produce 20 N bite-forces for each muscle and subject determined thresholds (5–80%·T20 N) for subject-specific DF calculations during exercises performed in laboratory and natural environments. Subjects self-recorded via portable electromyography equipment during in-field leg-extension and weight-lifting exercises. Effects of variables on DFs were assessed via ANOVA (α = 0.05) and simple effects testing (Bonferroni-adjusted p  0.012). All subjects used jaw muscles during exercises in both environments. DFs between laboratory sessions were reliable (R = 0.84). During laboratory exercises, male temporalis DFs were significantly higher than female DFs from both muscles (p  0.001). During in-field exercises females had higher DFs during weight-lifting while males had higher DFs during leg-extensions. In-field sex differences were significant at most thresholds and showed larger effect sizes for leg-extension compared to weight-lifting exercises.  相似文献   

7.
《Cryobiology》2013,66(3):319-325
The present study aimed to evaluate the effect of methyl-β-cyclodextrin (MβCD) as a cholesterol loader to change oocyte plasma membrane and increase its tolerance toward cryopreservation. The first and second experiments were conducted to investigate if MβCD could improve nuclear and cytoplasmic maturation after oocyte exposure to cold stress for 10 or 30 min, respectively. No differences (P > 0.05) in either experiment in the metaphase II (MII) rate of oocytes exposed to MβCD and cold stress; but these oocytes presented lower maturation rates than control groups. In the second experiment, a lower percentage of oocytes showed degenerated chromatin (P < 0.05) after exposure to 2 mg/mL of MβCD compared to the group exposed to 0 mg/mL. However, no differences among treatments were observed in cytoplasmic maturation. Groups exposed to cold stress demonstrated a lower (P < 0.05) capacity for embryonic development compared to the control groups. In the third experiment immature oocytes were exposed to MβCD and then, vitrified (cryotop). After warming, we observed that the ability to reach MII and chromatin degeneration were altered (P < 0.05) by MβCD. The blastocysts rate (P < 0.05) on D7 was higher in the 2 mg/mL MβCD group, but an identical finding was not observed on D8 (P > 0.05). Chromatin degeneration was higher in the vitrification groups. We conclude that MβCD improved nuclear maturation by reducing oocyte degeneration after cold stress or vitrification; however, more studies are required to clarify the usefulness of MβCD use in oocyte cryopreservation.  相似文献   

8.
Aim: Extracellular matrix metalloproteinase inducer (EMMPRIN) has been shown to promote tumor invasion and metastasis via stimulating matrix metalloproteinase synthesis in neighboring fibroblasts, to enhance angiogenesis via vascular endothelial growth factor, to induce chemoresistant tumor cells via the production of hyaluronan, and to confer resistance of cancer cells to anoikis through inhibition of Bim. The purpose of this study was to investigate the expression of EMMPRIN in human primary bladder cancer and to evaluate its prognostic value. Methods: EMMPRIN expression patterns were detected by immunohistochemistry. In order to determine its prognostic value, overall survival (OS) and progression-free survival (PFS) were evaluated using the Kaplan–Meier method, and multivariate analysis was performed using the Cox proportional hazard analysis. Results: Of the 101 cases with bladder cancers, 68 (67.3%) cases were positive for EMMPRIN expression. When categorized into negative vs. positive expression, EMMPRIN was associated with the stage (p = 0.006), the grade (p = 0.002), carcinoma in situ (p = 0.01), the recurrence (p = 0.009), the progression (p = 0.009), and the death (p = 0.01) of patients with bladder cancer. Moreover, positive EMMPRIN expression clearly predicted poorer PFS (p = 0.008) and OS (p = 0.006). In the multivariate analysis, positive EMMPRIN expression was an independent prognostic factor for PFS (p = 0.03) and OS (p = 0.03). Conclusion: EMMPRIN expression was greater in bladder cancers than in the adjacent normal tissues and may be a useful prognostic marker for patients with bladder cancer.  相似文献   

9.
《Process Biochemistry》2014,49(10):1664-1672
Hydroxysafflor yellow A (HSYA) is a potent natural antioxidant that displays important neuroprotective activity. Inhibition of acetaldehyde dehydrogenase 1 (ALDH1) has attracted the attention of researchers due to its overexpression in several types of cancers. We studied the effects of HSYA on ALDH1 by evaluating the inhibitory kinetics based on its antioxidant properties and performing computational simulation integrating methods. HSYA reversibly inhibited human recombinant ALDH1 via non-competitive inhibition (Ki = 0.267 ± 0.024 mM). We also investigated the tertiary structural changes via measuring intrinsic and ANS-binding fluorescence. The results indicated that the inactivation induced by HSYA was associated with structural changes. To obtain further information, we simulated the 3D structure of ALDH1 and conducted computational docking simulations as well as molecular dynamics simulations. The results indicated that 4 rings of HSYA interact with several residues near the ALDH1 active site. Our study provides insight into the inhibition of ALDH1 accompanied by structural changes. Based on its ALDH1-inhibiting effect and its potential as a natural antioxidant, HSYA is a potential agent for treating ALDH1-associated cancers.  相似文献   

10.
Hildegardia species are an important resource for fiber industry. This investigation was conducted to develop a plant regeneration protocol for Hildegardia populifolia (Roxb.) Schott & Endl. via indirect organogenesis Callus was obtained from leaf, internode and petiole explants, among these explants internode explant gave best result on MS medium supplemented with different concentrations of 2,4-Dichlorophenoxy acetic acid (2,4-D). The highest percentage (100%) of regeneration was obtained with benzyladenine (BA) (2.0 mg/l) + indole-3-acetic acid (IAA) (0.1 mg/l) + glutamine (25 mg/l) + thidiazuron (TDZ) (0.5 mg/l) from internode explants. Shootlets were highly rooted on MS medium supplemented with 3.0 mg/l indole-3-butyric acid (IBA). In vitro rooted seedlings were successfully acclimatized. This in vitro regeneration system will facilitate further development of reliable procedures for this genus.  相似文献   

11.
Lipase from Thermomyces lanuginosus (TLL) was immobilized on mesoporous hydrophobic poly-methacrylate (PMA) particles via physical adsorption (interfacial activation of the enzyme on the support). The influence of initial protein loading (5–200 mg/g of support) on the catalytic properties of the biocatalysts was determined in the hydrolysis of olive oil emulsion and synthesis of isoamyl oleate (biolubricant) by esterification reaction. Maximum adsorbed protein loading and hydrolytic activity were respectively ≈100 mg/g and ≈650 IU/g using protein loading of 150 mg/g of support. The adsorption process followed the Langmuir isotherm model (R2 = 0.9743). Maximum ester conversion around 85% was reached after 30 min of reaction under continuous agitation (200 rpm) using 2500 mM of each reactant in a solvent-free system, 45 °C, 20% m/v of the biocatalyst prepared using 100 mg of protein/g of support. Apparent thermodynamic parameters of the esterification reaction were also determined. Under optimal experimental conditions, reusability tests of the biocatalyst (TLL-PMA) after thirty successive cycles of reaction were performed. TLL-PMA fully retained its initial activity up to twenty two cycles of reaction, followed by a slight decrease around 8.6%. The nature of the product (isoamyl oleate) was confirmed by attenuated total reflection Fourier transform infrared (ATR-FTIR), proton (1H NMR) and carbon (13C NMR) nuclear magnetic resonance spectroscopy analyses.  相似文献   

12.
Patent Reports     
We synthesized a hydroquinone glucoside (HG) as a potential skin-whitening agent using Leuconostoc mesenteroides (B-1299CB BF563) dextransucrase with hydroquinone (HQ) as an acceptor and sucrose as a donor. The product was purified using butanol partitioning and silica gel column chromatography. The structure of the purified HG was determined by nuclear magnetic resonance and the ionic product was observed at m/z 295 (C12, H16, O7 Na)+. HG was identified as 4-hydroxyphenyl-α-d-glucopyranoside. The optimum condition of HG synthesis, determined using a response surface methodology, was 450 mM HQ, 215 mM sucrose, and 0.55 U/mL dextransucrase; the final HG produced was 544 mg/L. The IC50 of diphenylpicryl-hydrazyl scavenging activity was 3.85 mM indicating a higher antioxidant activity compared to β-arbutin (IC50 = 6.04 mM). HG-mediated inhibition of lipid peroxidation was 3.51% that of HQ (100%) and much higher than that of β-arbutin (0.81% of HQ). In addition the IC50 value of nitrite-scavenging activity was 14.76 mM showing a superior scavenging activity to that of β-arbutin (IC50 = 27.09 mM).  相似文献   

13.
14.
One of the most attractive segments in food and cosmetic industries is that of natural pigments. Since some synthetic pigments have been reported to be hazardous for humans, natural pigments obtained through biotechnological processes represent an attractive alternative. Our research group has previously worked on the development of an aqueous two-phase system (ATPS)-based prototype process for the recovery of B-phycoerythrin (BPE), a natural high-value pigment obtained from Porphyridium cruentum. Detailed studies describing the scaling up of ATPS processes from bench scale to pilot plant facilities are not common. In this paper experiences derived from the scale-up of a previously developed process for production and recovery of highly purified (purity defined as the absorbance ratio A545/A280 > 4) BPE are described, where a scale-up factor of 850× was implemented. Characterization of cell disruption with a pilot-scale bead mill allowed efficient BPE release at 2900 rpm, 10% (w/v) sample load, 60% (v/v) bead load and 0.5 mm glass beads and 22 min of residence time with a yield of 1.35 mg BPE/g of wet biomass. BPE was recovered and purified using a strategy comprising isoelectric precipitation, aqueous two-phase fractionation and ultrafiltration. A 54% global BPE recovery yield, with final purity of 4.1, was achieved under optimal process conditions. Considering total costs for raw materials and energy expenditures for one batch, it was determined that the production cost of BPE was of $1.17 USD/mg, which is underneath the commercial price of a BPE standard (>$30 USD/mg).  相似文献   

15.
The synthesis of oligo(ethylene glycol)-alkene substituted theophyllines in positions 7 and/or 8 is described. The binding activity at adenosine receptors of selected derivatives was studied. Compound 2 showed high affinity for human A2B receptor (Ki = 4.16 nM) with a selectivity KiA2A/KiA2B of 24.1, and a solubility in water of 1 mM. The alkenyl substituent in some of the theophylline derivatives allows for covalent attachment of them onto hydrogen-terminated silicon substrate surfaces via hydrosilylation. Alternatively, an azido group was incorporated to an oligo(ethylene glycol)theophylline derivative as an anchor for tethering the molecules on ethynyl presenting surfaces via click reaction.  相似文献   

16.
Biological screening of a library of synthesized benzo[c]chromene-7,10-dione natural products against human farnesyltransferase (FTase) has identified tecomaquinone I (IC50 of 0.065 ± 0.004 μM) as being one of the more potent natural product inhibitors identified to date. Anti-plasmodial screening of the same library against a drug-resistant strain of Plasmodium falciparum identified the structurally-related dichromenol tectol as a moderately active growth inhibitor with an IC50 3.44 ± 0.20 μM. Two novel series of analogues, based on the benzo[c]chromene-7,10-dione scaffold, were subsequently synthesized, with one analogue exhibiting farnesyltransferase inhibitory activity in the low micromolar range. A preliminary structure–activity relationship (SAR) study has identified different structural requirements for anti-malarial activity in comparison to FTase activities for these classes of natural products. Our results identify tecomaquinone I as a novel scaffold from which more potent inhibitors of human and parasitic FTase could be developed.  相似文献   

17.
《Small Ruminant Research》2009,85(1-3):108-115
Seventy full lactations of Payoya dairy goats were used to study the effect of two different kid-rearing systems, natural or artificial, on milk yield, composition, hygiene-sanitary quality, kid growth and rearing cost. Two animal groups were established, one with goats under natural rearing (NS) and the other under artificial rearing (AR). In the NS group, the kids had free access to goat milk 18–20 h a day and were suckled up to 5 weeks of age and then the dams were milked twice daily. Dams in the AR were separated from their kids at 48 h post-partum; then, kids were reared artificially, and the dams were milked twice daily. The number of animals used in each type of rearing system was 35 (23 goats giving birth to twins and 12 goats giving birth to a single kid). Each week during suckling phase the volume of milk produced was measured, and individual samples were taken. From 5th week and until 210 days lactation, test-day yields recorded at intervals of 30 ± 3 days were obtained. The chemical composition of the milk, the bacteriology, and the somatic cell count was analyzed. The kids of both sexes were assigned to two groups, natural suckling (NS, n = 58) and ad libitum artificial rearing (AR, n = 58). Within each treatment, two groups of kids were formed depending on prolificacy: first group with kids from single birth (n = 12) and the second with twin kids (n = 46). Birth weight and weight every week upto the 4th week of life were recorded. During the 5 weeks of lactation the total milk yield per goat was higher for the NS group (140.2 L vs. 95.4 L; P < 0.001), although the total amount of marketable milk was greater for the AR group, with a difference of some 21 L (P < 0.05). Throughout the entire lactation the milk yield was higher in the group of natural rearing (total yield of 508 L vs. 400 L; P < 0.05). Although a significant effect of prolificacy was found during suckling phase (P < 0.001), during 30 weeks of lactation this factor did not affect milk yield (P > 0.05). For the milk composition and hygiene-sanitary quality there were no effects on the type of rearing system or the type of birth (P > 0.05). No significant effect was observed either for the feeding system or the sex or the prolificacy on the live weight of the kids at 28 days and the postnatal growth rate from birth to 28 days (P > 0.05). Natural rearing system had higher cost per kid comparing with artificial rearing system (€18.63/kid vs. €14.70/kid, respectively). However, when comparing total incomes during a full lactation, goats with natural rearing system had a higher income because of increment of total milk production (€29.95/kid).  相似文献   

18.
IntroductionTo assess interobserver variability for biological target volume (BTV) delineation and to compare the reproductibility of different semiautomatic segmentation methods in pretreatment 18-fluorodeoxyglucose positron emission tomography (PET/CT) of head and neck squamous cell carcinoma (HNSCC).Patients and methodsPatients with histologically proved HNSCC referred to the nuclear medicine service in Brest for pretreatment PET/CT were prospectively included from February 2009 to June 2010. Three nuclear medicine physicians (two specialized in oncology) delineated manually and independently BTV on each primary tumor. Four semiautomatic segmentation methods have been studied; three using a fixed threshold and one applying an adaptive threshold based on the signal-to-background ratio (Daisne). The variability between κ observers and/or methods has been assessed. The concordance between the various BTV intersections and unions has been also assessed.ResultsThirty patients (29M; 1F) were included. The primary site location was oropharynx in six patients, oral cavity in 10 patients, hypopharynx in five patients and larynx in nine patients. A statistically significant global interobserver variability (P = 0.01) was showed, but without statistically difference between the two experienced oncologists (P = 0.15). The maximal concordance of the two experienced observers with the semiautomatic methods was found for the Daisne method (CI = 61.5%; κ = 0.68), expressing a good agreement according to the Landis and Koch criteria, better than with the segmentation method using a fixed threshold with 40% of maximal signal intensity (CI = 52.1%; κ = 0.53).ConclusionOur results suggest the feasibility of achieving HNSCC BTV delineation by PET/CT using semiautomatic methods, in particular those which apply an adaptative threshold but under the supervision of an experienced operator.  相似文献   

19.
Due to their less expensive, environment friendly nature, and their natural abundance of cobalt have attained more significant attention for the synthesis of cobalt nanoparticles. In the present study, we report the facile synthesis of cobalt nanoparticles using a straight forward chemical reduction approach of cobalt chloride with sodium borohydride and capping of sulfadimidine. sulfadimidine has strong capping eligibility on the surface of nanoparticles due to its chemical stability and is an applicable as stabilizer due to the existence of an amine bond. The as-synthesized sulfadimidine stabilized cobalt nanoparticles (Co-SD NPs) were characterized by using various spectroscopic and microscopic analysis like UV–Visible spectroscopy (UV–Vis), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), High-Resolution Transmission electron microscopy (HR-TEM), and Fourier-transform infrared spectroscopy (FT-IR). The XRD analysis exhibited the triclinic crystal structure of the as-synthesized cobalt nanoparticles and FT-IR analysis confirmed the capping of sulfadimidine via monodentate interaction. The HR-TEM analysis displayed the size of the cobalt nanoparticles approximately 3–5 nm. The antibacterial properties of the sulfadimidine stabilized cobalt nanoparticles (Co-SD NPs) were tested against various bacterial strains such as Klebsiella pneumonia (KP), Escherichia coli (EC) and Pseudomonas syringae (PS) by using agar disc diffusion approach. The results of sulfadimidine capped cobalt nanoparticles displayed the enhanced biological properties against the tested gram-negative bacteria.  相似文献   

20.
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