Detection of Antibiotic Resistance in Feline-Origin ESBL Escherichia coli from Different Areas of China and the Resistance Elimination of Garlic Oil to Cefquinome on ESBL E. coli.

The development of drug-resistance in the opportunistic pathogen Escherichia coli has become a global public health concern. Due to the share of similar flora between pets and their owners, the detection of pet-origin antibiotic-resistant E. coli is necessary. This study aimed to detect the prevalence of feline-origin ESBL E. coli in China and to explore the resistance elimination effect of garlic oil to cefquinome on ESBL E. coli. Cat fecal samples were collected from animal hospitals. The E. coli isolates were separated and purified by indicator media and polymerase chain reaction (PCR). ESBL genes were detected by PCR and Sanger sequencing. The MICs were determined. The synergistic effect of garlic oil and cefquinome against ESBL E. coli was investigated by checkerboard assays, time-kill and growth curves, drug-resistance curves, PI and NPN staining, and a scanning electronic microscope. A total of 80 E. coli strains were isolated from 101 fecal samples. The rate of ESBL E. coli was 52.5% (42/80). The prevailing ESBL genotypes in China were CTX-M-1, CTX-M-14, and TEM-116. In ESBL E. coli, garlic oil increased the susceptibility to cefquinome with FICIs from 0.2 to 0.7 and enhanced the killing effect of cefquinome with membrane destruction. Resistance to cefquinome decreased with treatment of garlic oil after 15 generations. Our study indicates that ESBL E. coli has been detected in cats kept as pets. The sensitivity of ESBL E. coli to cefquinome was enhanced by garlic oil, indicating that garlic oil may be a potential antibiotic enhancer.

Intracellular location of aquaporin-2 serine 269 phosphorylation and dephosphorylation in kidney collecting duct cells.

Aquaporin-2 (AQP2) is a vasopressin-regulated water channel protein responsible for water reabsorption by the kidney collecting ducts. Under control conditions, most AQP2 resides in the recycling endosomes of principal cells, where it answers to vasopressin with trafficking to the apical plasma membrane to increase water reabsorption. Upon vasopressin withdrawal, apical AQP2 retreats to the early endosomes before joining the recycling endosomes for the next vasopressin stimulation. Prior studies have demonstrated a role of AQP2 S269 phosphorylation in reducing AQP2 endocytosis, thereby prolonging apical AQP2 retention. Here, we studied where in the cells S269 was phosphorylated and dephosphorylated in response to vasopressin versus withdrawal. In mpkCCD collecting cells, vacuolar protein sorting 35 knockdown slowed vasopressin-induced apical AQP2 trafficking, resulting in AQP2 accumulation in the recycling endosomes where S269 was phosphorylated. Rab7 knockdown, which impaired AQP2 trafficking from the early to recycling endosomes, reduced vasopressin-induced S269 phosphorylation. Rab5 knockdown, which impaired AQP2 endocytosis, did not affect vasopressin-induced S269 phosphorylation. Upon vasopressin withdrawal, S269 was not dephosphorylated in Rab5 knockdown cells. In contrast, S269 dephosphorylation upon vasopressin withdrawal was completed in Rab7 or vacuolar protein sorting 35 knockdown cells. We conclude that S269 is dephosphorylated during Rab5-mediated AQP2 endocytosis before AQP2 joins the recycling endosomes upon vasopressin withdrawal. While in the recycling endosomes, AQP2 can be phosphorylated at S269 in response to vasopressin before apical trafficking.

Rab7 involves Vps35 to mediate AQP2 sorting and apical trafficking in collecting duct cells.

Aquaporin-2 (AQP2) is a vasopressin-regulated water channel protein responsible for osmotic water reabsorption by kidney collecting ducts. In response to vasopressin, AQP2 traffics from intracellular vesicles to the apical plasma membrane of collecting duct principal cells, where it increases water permeability and, hence, water reabsorption. Despite continuing efforts, gaps remain in our knowledge of vasopressin-regulated AQP2 trafficking. Here, we studied the functions of two retromer complex proteins, small GTPase Rab7 and vacuolar protein sorting 35 (Vps35), in vasopressin-induced AQP2 trafficking in a collecting duct cell model (mpkCCD cells). We showed that upon vasopressin removal, apical AQP2 returned to Rab5-positive early endosomes before joining Rab11-positive recycling endosomes. In response to vasopressin, Rab11-associated AQP2 trafficked to the apical plasma membrane before Rab5-associated AQP2 did so. Rab7 knockdown resulted in AQP2 accumulation in early endosomes and impaired vasopressin-induced apical AQP2 trafficking. In response to vasopressin, Rab7 transiently colocalized with Rab5, indicative of a role of Rab7 in AQP2 sorting in early endosomes before trafficking to the apical membrane. Rab7-mediated apical AQP2 trafficking in response to vasopressin required GTPase activity. When Vps35 was knocked down, AQP2 accumulated in recycling endosomes under vehicle conditions and did not traffic to the apical plasma membrane in response to vasopressin. We conclude that Rab7 and Vps35 participate in AQP2 sorting in early endosomes under vehicle conditions and apical membrane trafficking in response to vasopressin.

Low-dose phloretin alleviates diabetic atherosclerosis through endothelial KLF2 restoration.

We investigated whether low-dose phloretin served as daily dietary supplements could ameliorate diabetic atherosclerosis and the role of kruppel-like factor 2 (KLF2). HUVECs cultured in high glucose medium were treated with different concentrations of phloretin and KLF2 mRNA, and protein level was detected. Diabetes was induced using streptozotocin in Apoe-/- mice after which they were fed a high-cholesterol diet for 8 weeks. Diabetic mice injected with KLF2 shRNA-lentivirus or control virus were treated with 20 mg/kg phloretin. Glucose, lipid profile, aortic atheroma, and endothelial nitric oxide synthase (eNOS) expression were detected. Phloretin retained endothelial function by KLF2-eNOS activation under hyperglycemia. Low-dose phloretin helped with lipid metabolism, and blocked the acceleration of atherosclerosis in STZ-induced diabetic mice since the early stage, which was diminished by KLF2 knockdown. Low-dose phloretin exhibited athero-protective effect in diabetic Apoe-/- mice dependent on KLF2 activation. This finding makes phloretin for diabetic atherosclerosis.

Transcription Factor Elf3 Modulates Vasopressin-Induced Aquaporin-2 Gene Expression in Kidney Collecting Duct Cells.

Aquaporin-2 (AQP2) is a molecular water channel protein responsible for water reabsorption by the kidney collecting ducts. Many water balance disorders are associated with defects in AQP2 gene expression regulated by the peptide hormone vasopressin. Here, we studied roles of Elf3 (E26 transformation-specific (Ets)-related transcription factor 3) in AQP2 gene expression in the collecting duct cells (mpkCCD). Vasopressin increased AQP2 mRNA and protein levels without affecting AQP2 mRNA degradation, indicative of transcriptional regulation. Elf3 knockdown and overexpression, respectively, reduced and increased AQP2 gene expression under basal and vasopressin-stimulated conditions. However, the vasopressin-to-basal ratios of AQP2 gene expression levels remained constant, indicating that Elf3 does not directly mediate vasopressin response but modulates the level of AQP2 gene expression inducible by vasopressin. The Elf3-modulated AQP2 gene expression was associated with AQP2 promoter activity, in line with Elf3's ability to bind an Ets element in the AQP2 promoter. Mutation in the Ets element reduced both basal and vasopressin-stimulated AQP2 promoter activity, again without affecting vasopressin-to-basal ratios of the AQP2 promoter activity. Lithium chloride reduced both Elf3 and AQP2 mRNA in the mpkCCD cells as well as in mouse kidney inner medulla. We conclude that Elf3 modulates AQP2 promoter activity thereby gauging vasopressin-inducible AQP2 gene expression levels. Our data provide a potential explanation to lithium-induced nephrogenic diabetes insipidus where lithium reduces Elf3 and hence AQP2 abundance.

Dose response and time course of manganese-enhanced magnetic resonance imaging for visual pathway tracing in vivo.

Axonal tracing is useful for detecting optic nerve injury and regeneration, but many commonly used methods cannot be used to observe axoplasmic flow and synaptic transmission in vivo. Manganese (Mn(2+))-enhanced magnetic resonance imaging (MEMRI) can be used for in vivo longitudinal tracing of the visual pathway. Here, we explored the dose response and time course of an intravitreal injection of MnCl2 for tracing the visual pathway in rabbits in vivo using MEMRI. We found that 2 mM MnCl2 enhanced images of the optic nerve but not the lateral geniculate body or superior colliculus, whereas at all other doses tested (5-40 mM), images of the visual pathway from the retina to the contralateral superior colliculus were significantly enhanced. The images were brightest at 24 hours, and then decreased in brightness until the end of the experiment (7 days). No signal enhancement was observed in the visual cortex at any concentration of MnCl2. These results suggest that MEMRI is a viable method for temporospatial tracing of the visual pathway in vivo. Signal enhancement in MEMRI depends on the dose of MnCl2, and the strongest signals appear 24 hours after intravitreal injection.

Antiviral activities of 15 dengue NS2B-NS3 protease inhibitors using a human cell-based viral quantification assay.

The dengue virus is a mosquito-borne pathogen responsible for an estimated 50-100 million human dengue infections annually. There are currently no approved drugs against this disease, resulting in a major unmet clinical need. The dengue viral NS2B-NS3 protease has been identified as a plausible drug target due to its involvement in viral replication in mammalian host cells. In the past decade, at least 20 dengue NS2B-NS3 protease inhibitors have been reported in the literature with a range of inhibitory activities in protease assays. However, such assays do not shed light on an inhibitor's ability to penetrate human cell membranes where the viral protease resides. In this study, we investigated the antiviral activities of 15 small-molecule and peptide-based NS2B-NS3 inhibitors on dengue serotype 2-infected HuH-7 human hepatocarcinoma cells. Experimental results revealed anthraquinone ARDP0006 (compound 5) to be the most potent inhibitor which reduced dengue viral titer by more than 1 log PFU/mL at 1 µM in our cell-based assays involving HuH-7 and K562 cell lines, suggesting that its scaffold could serve as a lead for further medicinal chemistry studies. Compound 5 was also found to be non-cytotoxic at 1 µM over 3 days incubation on HuH-7 cells using the Alamar Blue cellular toxicity assay.

[Effect of fertilization levels on soil microorganism amount and soil enzyme activities].

Field experiments were conducted in Shangluo pharmaceutical base in Shaanxi province to study the effect of nitrogen, phosphorus and potassium in different fertilization levels on Platycodon grandiflorum soil microorganism and activities of soil enzyme, using three-factor D-saturation optimal design with random block design. The results showed that N0P2K2, N2P2K0, N3P1K3 and N3P3K1 increased the amount of bacteria in 0-20 cm of soil compared with N0P0K0 by 144.34%, 39.25%, 37.17%, 53.58%, respectively. The amount of bacteria in 2040 cm of soil of N3P1K3 increased by 163.77%, N0P0K3 increased the amount of soil actinomycetes significantly by 192.11%, while other treatments had no significant effect. N2P0K2 and N3P1K3 increased the amounts of fungus significantly in 0-20 cm of soil compared with N0P0K0, increased by 35.27% and 92.21%, respectively. N3P0K0 increased the amounts of fungus significantly in 20-40 cm of soil by 165.35%, while other treatments had no significant effect. All treatments decrease soil catalase activity significantly in 0-20 cm of soil except for N2P0K2, and while N2P2K0 and NPK increased catalase activity significantly in 2040 cm of soil. Fertilization regime increased invertase activity significantly in 2040 cm of soil, and decreased phosphatase activity inordinately in 0-20 cm of soil, while increased phosphatase activity in 2040 cm of soil other than N1P3K3. N3P0K0, N0P0K3, N2P0K2, N2P2K0 and NPK increased soil urease activity significantly in 0-20 cm of soil compared with N0P0K0 by 18.22%, 14.87%,17.84%, 27.88%, 24.54%, respectively. Fertilization regime increased soil urease activity significantly in 2040 cm of soil other than N0P2K2.

[Responses of Scutellaria baicalensis Georgi yield and root baicalin content to the fertilization rates of nitrogen, phosphorus, and potassium].

A field experiment with three-factor (N, P, and K) and quadratic saturation D-optimal design was conducted to evaluate the effects of the fertilization rates of N, P, and K on the yield and root baicalin content of Scutellaria baicalensis Georgi at harvesting time. A ternary quadratic polynomial mathematical model was built, in which, the N, P, and K fertilization rates were independent variables, and the yield and root baicalin content were the target functions. Through the analysis of the model, the optimum fertilization pattern was obtained. The results showed that the fertilization rates of N and P had significant effects on the yield of S. baicalensis. Under low fertilization level, the yield increased with increasing N and P fertilization rates; after exceeding definite fertilization range, no obvious effects were observed. N, P, and K fertilization all had significant effects on the root baicalin content. With increasing fertilization rates of N and K, the root baicalin content rates decreased after an initial increase. Under low fertilization level, the root baicalin content increased with increasing P fertilization rate first, and kept stable then. There existed interactive effects between the fertilization rates of N and P, N and K, and P and K on the yield and root baicalin content of S. baicalensis. Under our experimental conditions, the optimum fertilization model for obtaining over 4000 kg x hm(-2) of S. baicalensis yield and > 14% of root baicalin content was 90.5-104.7 kg x hm(-2) of N, 163.9-199.9 kg x hm(-2) of P2O5, and 84.1-140.8 kg x hm(-2) of K2O, with an N:P2O5:K2O ratio of approximately 1:1.86:1.15.

Clinical characteristics of hepatitis B virus infection in middle school students born after the universal infant vaccination program in Shanghai, China.

The aim of this study was to investigate the prevalence of hepatitis B surface antigen (HBsAg) and clinical characteristics of middle school students infected with hepatitis B virus (HBV) after initiation of the HBV immunization program in China. A total of 82,156 serum samples were collected from students in 33 junior schools and 25 senior schools. HBsAg was tested by ELISA. Samples from HBsAg-positive students were collected and analyzed for HBV serum markers, alanine aminotransferase (ALT), HBV DNA levels, and HBV genotypes. The overall prevalence of HBsAg was 1.11% in middle school students in Shanghai, China. The prevalence of HBsAg in students born during the immunization program to HBsAg-positive mothers was significantly higher than that in students born during the universal vaccination program (1.47% vs 0.78%, P < 0.01). Only HBV genotypes B and C were found in these infections, and genotype C was the dominant one. Twenty-one (13.0%) of 162 HBsAg-positive students had active hepatitis B, and 18 were hepatitis B e antigen (HBeAg) positive. The universal infant vaccination program has reduced the prevalence of HBsAg significantly. HBeAg-positive hepatitis B, however, needs to be monitored among the students in whom vaccination failed.

[Seedling index of Salvia miltiorrhiza and its simulation model].

Through the correlation analysis on the quantitative traits and their ratios of Salvia miltiorrhiza seedlings and seedling quality, a series of representative indices reflecting the seedling quality of the plant species were determined, and the seedling index suitable to the S. miltiorrhiza seedlings was ascertained by correlation degree analysis. Meanwhile, based on the relationships between the seedling index and the air temperature, solar radiation and air humidity, a simulation model for the seedling index of S. miltiorrhiza was established. The experimental data of different test plots and planting dates were used to validate the model. The results showed that the root diameter, stem diameter, crown dry mass, root dry mass, and plant dry mass had significant positive relationships with the other traits, and could be used as the indicators of the seedling's health. The seedling index of S. miltiorrhiza could be calculated by (stem diameter/root diameter + root dry mass/crown dry mass) x plant dry mass. The stem diameter, root dry mass, crown dry mass and plant dry mass had higher correlations with the seedling index, and thus, the seedling index determined by these indicators could better reflect the seedling's quality. The coefficient of determination (R2) between the predicted and measured values based on 1:1 line was 0.95, and the root mean squared error (RMSE) was 0.15, indicating that the model established in this study could precisely reflect the quantitative relationships between the seedling index of S. miltiorrhiza and the environmental factors.

[Clinical significance of heterozygosity loss at Mfn2 gene in hepatocellular carcinoma].

OBJECTIVE: To investigate the loss of heterozygosity (LOH) at mitofusin-2 (Mfn2) gene in hepatocellular carcinoma (HCC) and its clinicopathological significance. METHODS: Four high polymorphic microsatellite markers flanking Mfn2 were selected for LOH analysis in 29 cases of HCC. RESULT: The frequencies of LOH on D1S2667, D1S2740, D1S434 and D1S228 were 21%, 23%, 21% and 22%, respectively. LOH at Mfn2 was closely correlated with tumor size, age, capsule, differentiation and t HBV infection (P<0.05), not with gender, thrombosis, cirrhosis and serum AFP levels (P>0.05). CONCLUSION: LOH at Mfn2 gene in HCC is associated with the clinicopathological features of patients.

[Effects of nitrogen, phosphorus and potassium application on growth and active ingredient of Astragalus membranaceus].

OBJECTIVE: To study the effects of fertilizers with the different proportional of nitrogen, phosphorus and potassium on growth and active ingredient of Astragalus membranaceus. METHOD: Field experiment was conducted based on the D-saturation optimal design with three factors of nitrogen, phosphorus and potassium. The effects on growth and active ingredient of A. membranaceus were analyzed. RESULT: Fertilization promoted the seedling growth and provided abundant supply of nutrition for growth of root, yield and accumulation of active ingredient at the later growth stage, and increased the accumulation of dry matter of stem-leaf and root system. The effect of nitrogen, phosphorus and potassium application on the total dry matter accumulation of A. membranaceus was as following: nitrogen > potassium > phosphorus; the effect on the stem-leaf dry matter accumulation was as following: nitrogen > phosphorus > potassium; the effect on the root dry matter accumulation was as following: nitrogen > potassium > phosphorus. Nitrogen, phosphorus and potassium fertilizer increased the root yield of A. membranaceus. Obviously, the effect on the root yield was as following: nitrogen > potassium > phosphorus. The application of different proportional with nitrogen, phosphorus and potassium increased the content of polysaccharide and astragaloside, but had no distinct effect on the content of total flavonoids. The effect on the content of polysaccharide was as following: potassium > phosphorus > nitrogen, but the effect on the conten,t of astragaloside was as following: nitrogen > potassium > phosphorus. CONCLUSION: Nitrogen and potassium fertilizer application had more important effect on growth, yield and the contents of polysaccharide and astragaloside in A. membranaceus. During medicinal plants cultivation process, it should pay attention to the application of nitrogen fertilizer and potassium fertilizer and make balance application of nitrogen, phosphorus and potassium fertilizer.

Effects of grape seed proanthocyanidin extracts on peripheral nerves in streptozocin-induced diabetic rats.

Diabetic peripheral neuropathy (DPN) is one of the most common diabetic chronic complications. The aim of this study was to clarify whether grape seed proanthocyanidins extracts (GSPE) are therapeutic agents against DPN. In this study, we used streptozocin (STZ) to induce diabetic rats. GSPEs (250 mg/kg body weight/d) were administrated to diabetic rats for 24 wk. Motor nerve conductive velocity (MNCV) and mechanical hyperalgesia were determined in the rats. Serum glucose, glycated hemoglobin, advanced glycation end products (AGEs), and tissue malondialdehyde (MDA) and superoxide dismutase (SOD) were determined. Light and electron microscopy were used to observe the changes of nerval ultrastructure.GSPE significantly increased the MNCV, mechanical hyperalgesia and SOD of diabetic rats (p<0.05) and reduced the AGEs and MDA of diabetic rats (p<0.05). After being treated by GSPE, the severe segmental demyelination was decreased and Schwann cells were improved. In conclusion, GSPE plays an important role against DPN. With the decreasing of AGEs and MDA, it can ameliorate oxidation-associated nerval damage. This study may provide a new recognition of natural medicine for the treatment of DPN.

[Determination of mineral elements in different part of Astragalus membranaceus(Fisch.) by FAAS].

Having digested the root and shoot of Astragalus membranaceus (Fisch.) with the mixture of nitric acid and perchloride acid (4 : 1) under the condition of the bolling point and the normal pressure, the contents of the five mineral elements necessary to humanity, potassium, copper, zinc, iron and manganese in root and shoot of Astragalus membranaceus (Fisch.) were determined by flame atomic absorption spectroscopy (FAAS), and the results were analyzed in statistics. The correlative coefficient of the standard curve in this method is 0.997 3-0.999 9, the recovery of standard addition was 92.88%-109.25% and the relative standard deviation (RSD, n = 5) was 0.393 5%-3.175 2%. The method is simple and the results were accurate and reliable. The contents of K, Fe, Zn, Mn, Cu in the root and shoot of Astragalus membranaceus (Fisch.) were compared. The results showed that the sequence of the content of metal elements is as follows in all samples: K > Fe > Zn > Mn > Cu. However, the distribution of elements in shoot and root is not uniform, and the content of Fe, Zn and Cu in root is richer than in shoot. There are abundant Fe, Zn and Cu in root, for example, the content of Fe in root is 1.54 times that in shoot. In addition, there are also abundant mineral elements in the shoot, especially in K and Mn, for example, the content of K in shoot is 1.63 times that in root. The contents of K, Fe, Zn, Mn and Cu in shoot are in agreement with the medical effects of Astragalus membranaceus (Fisch.). The results should provide useful data for investigating the distribution of mineral element in Astragalus membranaceu body and the correlation between the mineral element content and the effect of medicine in Astragalus membranaceus (Fisch.).

[Study on difference of biological characteristics and resistance to powdery mildew of different Astragalus populations].

OBJECTIVE: To study difference among populations which belong to Astragalus membranaceus and A. membranaceus var. mongholicus on morphology, habit, characteristics of physiology and resistance to powdery mildew, and classify them in order to provide theoretical basis for breeding and improving varieties. METHOD: Morphology, habits, isozyme and soluble protein electrophoretograms were compared among the populations. They were categorized by cluster analysis based on those electrophoretograms. Different ability of resistance to powdery mildew was also studied through comparing disease indices among six populations. RESULT: The results showed A. membranaceus var. mongholicus was distinctly different from A. membranaceus. There was a special type in colonies of A. membranaceus, which showed hairy upper epidermis of leaflets and later florescence. CONCLUSION: Astragalus for medicine could be categorized in three types A. membranaceus var. mongholicus, A. membranaceus early florescence type and A. membranaceus late florescence type. Among them A. membranaceus var. mongholicus is most resistant to powdery mildew, while A. membranaceus is easily infected, and the early florescence type is even more easily infected.

Study of two-dimensional barcode prescription system for pharmacists' activities of NHI contracted pharmacy.

To lower the cost and enhance the quality of healthcare service, the Taiwan government launched National Health Insurance (NHI) in 1995 and the System of Separation of Medicine and Pharmacy in 1997. After the separation of dispensing and prescribing (SDP), pharmacists in NHI-contracted pharmacies have the right to fill prescriptions from a clinic. This means that pharmacists in NHI-contracted pharmacies have four more activities than previously. How to improve the additional activities remains an issue to be solved. Today, in most countries, patients deliver a written prescription to the pharmacy of their choice. The pharmacist validates the prescription and dispenses the drug. In this paper, we describe an automatic data collection system, the two-dimensional barcode prescription system (2DBPS) for pharmacists. The system allows patients to deliver a paper prescription with a 2D barcode issued by a clinic to the pharmacy of their choice. The pharmacist scans in the 2D barcode, validates the prescription, and dispenses the drug. Evaluation of the 2DBPS showed that most pharmacists use it to execute additional activities and it was more efficient than before. Moreover, the easy-to-use 2DBPS is accepted and appreciated by pharmacists. We can thus conclude that the aim of the 2DBPS is to reduce the workload of pharmacist in data processing. It will help pharmacists to expand their role beyond simple dispensing and data processing to providing pharmaceutical care services.

Yellow fever virus NS3 protease: peptide-inhibition studies.

A recombinant form of yellow fever virus (YFV) NS3 protease, linked via a nonapeptide to the minimal NS2B co-factor sequence (CF40-gly-NS3pro190), was expressed in Escherichia coli and shown to be catalytically active. It efficiently cleaved the fluorogenic tetrapeptide substrate Bz-norleucine-lysine-arginine-arginine-AMC, which was previously optimized for dengue virus NS2B/3 protease. A series of small peptidic inhibitors based on this substrate sequence readily inhibited its enzymic activity. To understand the structure-activity relationship of the inhibitors, they were docked into a homology model of the YFV NS2B/NS3 protease structure. The results revealed that the P1 and P2 positions are most important for inhibitor binding, whilst the P3 and P4 positions have much less effect. These findings indicate that the characteristics of YFV protease are very similar to those reported for dengue and West Nile virus proteases, and suggest that pan-flavivirus NS3 protease drugs may be developed for flaviviral diseases.

[Study on accumulation of dry matter and aborption of N, P and K of Astragalus membranaceus].

OBJECTIVE: To study Astragalus membranaceus absorption characteristic of nitrogen, phosphorus and potassium at different growth stages. METHOD: Through the field experiment and the sampling analysis, the absorbing capacity of nitrogen, phosphorus and potassium as well as the growth of plant at different growth stages in A. membranaceus were analyzed. RESULT: The dry matter accumulation reached 88.22% of the total accumulation in 100-163 days after seedling emergence, The content of N, P, K in the stem was higher than that in the root system. Nitrogen, phosphorus and potassium absorbing capacity in the stem, the leaf and the root systems was N > K > P. In the whole growth period, nitrogen accumulation reached the highest, and followed with the accumulation of potassium, and the accumulation of phosphorus was the lowest. In the last phase of the exuberant growth period, the accumulation intensity of nitrogen, phosphorus and potassium reduced. During the harvesting time, the accumulation intensity of nitrogen and potassium increased, and the accumulation intensity of phosphorus remained stable. CONCLUSION: The dry matter accumulation reached the maximum in 100-163 days after seedling emergence. The absorption strength of nitrogen, phosphorus and potassium in aerial part reached the maximum in 100-132 days after seeding emergence, the maximum absorption comes earlier than that of phosphorus and potassium, at that time the needs of nutrients reach the highest. For producing of 100 kg A. membranaceus 2.32 kg N, 0.323 kg P2O5, 1.62 kg K2O are needed to be absorbed from soil and fertilizer.

Peptide inhibitors of West Nile NS3 protease: SAR study of tetrapeptide aldehyde inhibitors.

A series of inhibitors related to the benzoyl-norleucine-lysine-arginine-arginine (Bz-nKRR) tetrapeptide aldehyde was synthesized. When evaluated against the West Nile virus (WNV) NS3 protease, the measured IC(50) ranges from approximately 1 to 200 microM. Concurrently, a modeling study using the recently published crystal structure of the West Nile NS3/NS2B protease complex (pdb code 2FP7) was conducted. We found that the crystal structure is relevant in explaining the observed SAR for this series of tetrapeptides, with the S1 and S2 pockets being the key peptide recognition sites. In general, a residue capable of both pi-stacking and hydrogen bonding is favored in the S1 pocket, while a positively charged residue is preferred in the S2 pocket. This study not only confirms the importance of the NS2B domain in substrate-based inhibitor binding of WNV, it also suggests that the crystal structure would provide useful guidance in the drug discovery process of related Flavivirus proteases, given the high degree of homology.