首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   58篇
  免费   5篇
  2024年   1篇
  2023年   3篇
  2022年   2篇
  2021年   5篇
  2020年   6篇
  2019年   9篇
  2018年   3篇
  2017年   2篇
  2016年   4篇
  2015年   2篇
  2013年   3篇
  2012年   8篇
  2011年   2篇
  2010年   4篇
  2009年   1篇
  2008年   1篇
  2007年   3篇
  2005年   2篇
  2001年   1篇
  1996年   1篇
排序方式: 共有63条查询结果,搜索用时 31 毫秒
21.
Early detection of colorectal cancer and monitoring the progress in colon carcinogenesis stages is essential to reduce mortality. Therefore, there is continuous search for noninvasive biomarkers with high stability and good sensitivity and specificity. miRNAs have attracted attention as promising biomarkers as they are stably expressed in circulation. The aim of our study is to evaluate the aberrant expression of circulating miRNAs during the stepwise progress of colitis-associated colon cancer. This was accomplished through assessing the expression levels of five miRNAs (miR-141, miR-15b, miR-17-3p, miR-21, and miR-29a) in serum and their corresponding tissue samples through the different cycles of colorectal carcinogenesis cascade using the azoxymethane/dextran sulfate sodium murine model. We also compared the diagnostic performance of these selected miRNAs with the conventional tumor biomarkers CEA and CA 19-9. The results of our study revealed that the expression levels of those miRNAs were dynamically changing in accordance with the tumor development state. Moreover, their aberrant expression in serum was statistically correlated with that in tissue. Our data also revealed that serum miR-15b, miR-21, and miR-29a showed the best performance in terms of diagnostic power. Our findings highlight the efficiency of these circulating miRNAs not only for early diagnostics purposes, but also for monitoring progress in the colorectal carcinogenesis process, and therefore encouraging integrating these noninvasive biomarkers into the clinical diagnostic settings beside the traditional diagnostic markers for accurate screening of the early progress of colon carcinogenesis.  相似文献   
22.
Preimplantation genetic diagnosis (PGD) is usually performed on blastomeres. In Germany, the only possibility to perform PGD is by analysis of polar bodies. We performed PGD using polar bodies in a woman who is a carrier of hemophilia A. Multiplex PCR followed by nested fluorescent PCR for five linked polymorphic markers was established. From 11 analyzed polar bodies, only 1 showed alleles linked to the mutation. The corresponding oocyte was transferred and no pregnancy was established. As seen in other investigations, the rate of heterozygous first polar bodies is surprisingly high.  相似文献   
23.
The effects of different fertilizers [the control with no fertilizer (C), inorganic fertilization (I), combined inorganic and organic fertilizer (IOHumax1) and (IOHumax2)] on yield and nutrients contents of two spinach varieties (“Balady and Virofly”) were investigated. Significant effects of variety were observed on vegetative growth and nutrients contents. While Virofly had significantly higher leaf area (236.96 cm2), stem diameter (7.43 mm) and fresh weight of vegetative and radical parts (15.05 and 0.96 g, respectively), Balady had significantly higher chlorophyll and carotene contents (0.0023 and 0.0018 g/g fw, respectively). No significant impacts of variety on vitamin C, nitrite, nitrate and oxalates contents were observed. IOHumax2 treatment (4 g/l of Humax + 100 mg/l of NH4NO3 per plant fertigation?1) enhanced stem diameter and root growth and significantly improved the yield by produced plants with higher stem length, leaf number and surface area. This treatment improved the quality of plant by increasing vitamin C content and reducing nitrite and oxalates contents. No significant effects of different fertilizers were observed on NO3 ? content. A fairly balanced yield/NO3 ? and oxalates content can be achieved with combined inorganic and organic fertilizer (IOHumax1) and (IOHumax2).  相似文献   
24.
25.
Nano-structure Cu(II) complex [Cu(AMAB)2]Cl2 with Schiff base (AMAB) derived from the condensation between 4-(dimethylamino)benzaldehyde and amoxicillin trihydrate was prepared. (AMAB) Schiff base and its Cu(II) complex were identified and confirmed by different physicochemical techniques. The Schiff base (AMAB) was coordinated to copper ion through carbonyl oxygen and imine nitrogen donor sites. X-ray powder diffraction shows a cubic crystal system of the Cu(II) complex. The density functional theory was used to optimize the structure geometries of the investigated compounds. The molecular docking of the active amino acids of the investigated proteins' interactions with the tested compounds was evaluated. The bactericidal or bacteriostatic effect of the compounds was screened against some bacterial strains. The activity of Cu-chelate against Gram-negative bacteria was mainly more effective than its (AMAB) ligand and vice versa in the case of Gram-positive bacteria. The biological activity of the prepared compounds with biomolecules calf thymus DNA (CT-DNA) was determined by electronic absorption spectra and DNA gel electrophoresis technique. All studies revealed that the Cu-chelate derivative exhibited better binding affinity to both CT-DNA than the AMAB and amoxicillin itself. The anti-inflammatory effect of the designed compounds was determined by testing their protein denaturation inhibitory activity spectrophotometrically. All obtained data supported that the designed nano-Cu(II) complex with Schiff base (AMAB) is a potent bactericide against H. pylori, and exhibits anti-inflammatory activity. The dual inhibition effects of the designed compound represent a modern therapeutic approach with extended spectrum of action. Therefore, it can act as good drug target in antimicrobial and anti-inflammtory therapies. Finally, H. pylori resistance to amoxicillin is absent or rare in many countries, thus amoxicillin nanoparticles may be beneficial for countries where amoxicillin resistance is reported.  相似文献   
26.
Hyperforin is an important antidepressant constituent of Hypericum perforatum (St. John's wort). Cell cultures of the related species H. calycinum were found to contain the homologue adhyperforin and to a low extent hyperforin, when grown in BDS medium in the dark. Adhyperforin formation paralleled cell culture growth. Cell-free extracts from the cell cultures contained isobutyrophenone synthase activity catalyzing the condensation of isobutyryl-CoA with three molecules of malonyl-CoA to give phlorisobutyrophenone, i.e. the hyperforin skeleton. The formation of the hyperforins during cell culture growth was preceded by an increase in isobutyrophenone synthase activity. The cell cultures also contained benzophenone synthase and chalcone synthase activities which are involved in xanthone and flavonoid biosyntheses, respectively. The three type III polyketide synthases were separated by anion exchange chromatography.  相似文献   
27.
The main task of the present work is to search for fungal strains isolated from agricultural soil with the potential to produce cellulases/xylanase enzyme preparation for bio-finishing of textiles. The most potent fungal strain (SAF6) was subjected to molecular identification using 18 SrRNA and was identified as Penicillium sp. SAF6 with the novel accession number of KM222497. Factors affecting the produced mixed enzyme activity were investigated. The optimum conditions for achieving maximum activity of the cellulases (FPase, CMCase and β-glucosidase) in addition to xylanase were the initial culture pH media 5, yeast extract (1.5gN/L), medium-to-air ratio (1:5) for FPase and CMCase and (1:10) for β-glucosidase, at 30?°C for 8 days incubation period. Potential application of the prepared crude enzyme in bio-finishing of cellulosic substrates, namely, bleached cotton, linen and indigo dyed fabrics were explored. Using the multi-component enzyme at appropriate dosage and conditions brought about a significant improvement and surface modification of the treated cotton substrates.  相似文献   
28.
Hepatitis C virus (HCV) infection is a major public health problem, having a high prevalence in Egypt. Leukemia and lymphoma have been associated with HCV infection. MicroRNA-155 (miR-155) has been reported to play a regulatory role in cancer, inflammation, and immune response to infection. The expression level of miR-155 in HCV viremic patients is controversial; although high miR-155 levels were demonstrated in HCV genotypes 1,2, and 3, low levels of miR-155 were detected in Egyptian patients with HCV genotype 4. Several studies have investigated the correlation between the levels of miRNA-155 and the replication of HCV, others have evaluated miRNA-155 as a prognostic biomarker in different types of cancer. No studies have investigated the impact of miRNA-155 knockdown on HCV pediatric patients associated with childhood acute lymphoblastic leukemia (ALL). We knocked-out the miR_155a in cultured polymorphonuclear cells (PBMCs) obtained from 60 children with ALL; 30 were associated with HCV-4 infection and 30 were HCV negative. The miR_155a, HCV viral load, and cell proliferation werre assessed in treated and untreated cells using TaqMan assay quantitative polymerase chain reaction. We found that miRNA-155 was significantly upregulated by seven folds in the HCV-4 associated ALL group; while being linked to high HCV viral load and leukemic burden, miR_155a knock-out can improve the disease outcome. We conclude that miR-155 is a critical miRNA that is considered a therapeutic target in pediatric HCV leukemic patients.  相似文献   
29.
Introduction and aimConsidering the magnitude of giardiasis problem, the side-effects of the used anti-giardia drugs and the resistance posed against them, the current study aimed to evaluate the in-vivo giardicidal effect of Psidium guajava leaf extract (PGLE).MethodsFor fulfilling this aim, five Swiss-albino mice groups were included; GI: non-infected, GII: Giardia-infected and non-treated, GIII: Giardia-infected and metronidazole-treated, GIV: Giardia-infected and PGLE-treated, and GV: Giardia-infected and treated with both metronidazole and PGLE. Treatment efficacy was assessed via; Giardia cyst viability and trophozoite count, trophozoite electron microscopic ultrastructure, duodenal histopathological scoring, immunohistochemistry for TNF-α and duodenal scanning electron microscopy. Moreover, mice serum liver enzymes, total bilirubin, albumin, lipid profile including; total cholesterol, HDL, LDL and triglycerides were assessed. Additionally, hepatic oxidative stress markers including; malondialdehyde (MDA), nitric oxide (NO), reduced glutathione (GSH) and superoxide dismutase (SOD) were measured.ResultsResults showed that PGLE whether alone or combined with metronidazole has induced significant trophozoite count reduction and major architectural changes. Duodenal histological improvement, and local protective anti-inflammatory effect were confirmed. PGLE has also helped in healing of Giardia-induced gut atrophy. Thus, offered a comprehensive therapy for both the pathogen and the resultant pathological sequalae. Serum markers showed favorable hepatoprotective effect. Total cholesterol, LDL and triglycerides levels were less in PGLE-treated group than in metronidazole-treated group. Hepatic oxidative stress markers revealed the promising extract antioxidant effect. This study highlights, the promising in-vivo giardicidal PGLE activity, that was comparable to metronidazole, thus, the extract would be an ideal strongly recommended treatment for giardiasis. When combined with metronidazole, the extract potentiated its therapeutic effect. Besides, having hepatoprotective, anti-inflammatory, and antioxidant properties, the extract can combat the major side effects of metronidazole therapy.  相似文献   
30.
We used a mixture of surrogates (Acinetobacter baumannii, Mycobacterium terrae, hepatitis A virus, and spores of Geobacillus stearothermophilus) for bioagents in a standardized approach to test environmental surface disinfectants. Each carrier containing 10 μl of mixture received 50 μl of a test chemical or saline at 22 ± 2°C. Disinfectant efficacy criteria were ≥6 log10 reduction for the bacteria and the spores and ≥3 log10 reduction for the virus. Peracetic acid (1,000 ppm) was effective in 5 min against the two bacteria and the spores but not against the virus. Chlorine dioxide (CD; 500 and 1,000 ppm) and domestic bleach (DB; 2,500, 3,500, and 5,000 ppm) were effective in 5 min, except for sporicidal activity, which needed 20 min of contact with either 1,000 ppm of CD or the two higher concentrations of DB.Disinfectant testing with a single type of organism does not represent field conditions, where bioagents or other pathogens may be mixed with other contaminants. Such an approach also cannot predict the true spectrum of microbicidal activity of a given chemical, while the identity of the target pathogen(s) is often unknown. We used a mixture of Acinetobacter baumannii, Mycobacterium terrae (15), hepatitis A virus (HAV) (4), and the spores of Geobacillus stearothermophilus as surrogates for infectious bioagents, with an added soil load on disks (1 cm in diameter; 0.75 mm thick) of brushed stainless steel (AISI no. 430; Muzeen & Blythe, Winnipeg, MB, Canada), to better simulate environmental surface disinfection (1, 11). Table Table11 gives details on the microbial strains, media used for their culture and recovery, and methods for preparing working stocks. The quantitative carrier test (QCT) method, ASTM standard E-2197 (1), was used to test the organisms singly and in a mixture. Each 200 μl of the inoculum contained 34 μl each of the four organisms, 40 μl of bovine mucin, 14 μl of yeast extract, and 10 μl of bovine serum albumin stocks.

TABLE 1.

Organisms in the mixture and their growth/recovery media and titers
Organism (ATCC no.)Growth/recovery medium or host cell lineProcedure for culture and prepn of stockViability titer in stock
Mycobacterium terrae pBEN genetically modified in-house (ATCC 15755)Middlebrook 7H11 agar, OADC,a and kanamycin (10 μg/ml); incubation 20 days at 36 ± 1°C7H9 broth with ADCb and glycerol; cells washed and resuspended in deionized water (8 ml) in a Bijoux bottle (Wheaton, Millville, NJ) with glass beads (Sigma-Aldrich; 3 mm in diam; catalog no. Z143928) and stored at 4°C3.7 × 109 CFU/ml
Geobacillus stearothermophilus (ATCC 12980)Trypticase soy agar plates incubated at 56°C for 48 hSpores heat shocked at 100°C for 45 min, washed in deionized H2O, and stored at 4°C1.5 × 108 CFU/ml
Acinetobacter baumannii (ATCC 19606)Trypticase soy agar plates incubated at 36 ± 1°C for 24 hInoculated into Trypticase soy broth and incubated for 24 h at 36 ± 1°C, broth centrifuged, and pellet resuspended in deionized H2O and stored at 4°C1.2 × 109 CFU/ml
Hepatitis A virus (ATCC VR-1402)FRhK-4 cells (CRL-1688) infected and incubated for 6 daysCells grown in MEMc with 7% (vol/vol) fetal bovine serum (Fisher; M33-500) and 1% nonessential amino acids (Gibco; 11140) at 36 ± 1°C, monolayers infected and incubated at 36 ± 1°C for 7 days in medium with no antibiotics, flasks frozen and thawed (thrice), cell lysate centrifuged, and supernatant aliquoted for storage at −80°C8 × 108 PFU/ml
Open in a separate windowaOADC, oleic acid-albumin-dextrose-catalase.bADC, albumin dextrose-catalase.cMEM, minimal essential medium.Disinfectants tested were peracetic acid (PAA; 500 and 1,000 ppm), chlorine dioxide (CD; 500 and 1,000 ppm), and domestic bleach (DB; 2,500, 3,300, and 5,000 ppm). Buffered saline (pH 7.2) was the control fluid, eluent, and diluent. Hard water (400 ppm CaCO3) was the diluent for disinfectants (1).Each disk received 10 μl of the inoculum, dried and covered with 50 μl of test substance, or saline at 22 ± 2°C. At the end of the contact time, each disk was eluted in a neutralizer and the eluates were assayed (1, 9, 11, 12). The neutralizer consisted of 1% dextrose (Difco), 0.7% lecithin (Alfa Aesar), 0.25% sodium bisulfite (J. T. Baker), 0.1% sodium thioglycolate (Sigma), 0.6% sodium thiosulfate (Analar), 0.2% l-cysteine (Sigma), 0.5% tryptone (Oxoid), and 0.1% Tween 80 (Bioshop) in buffered saline (pH 7.2). In each experiment, three control and three test carriers were used, and all experiments were repeated thrice. The performance criteria for the tested substances were ≥3.0 log10 reduction in PFU of the virus and ≥6.0 log10 reductions in the CFU for the other three organisms. When the mixture of test organisms was used, the components were separated by first passing the mixture through a membrane filter (0.22-μm pore diameter) to retain all the organisms except the virus. The filtrate was subjected to plaque assays for HAV in FRhK-4 cells. For the three bacteria, separate filters were placed on appropriate agar plates (Table (Table1)1) and incubated.The data for 5-min contact are given in Table Table2.2. All levels of the disinfectants tested met the criterion for M. terrae and A. baumannii when tested individually or in mixture. Only 1,000 ppm of PAA was effective against the spores. Both levels of PAA were ineffective against HAV, while the other disinfectants could reduce its titer between 3.5 and 4 log10. Only 1,000 ppm of PAA could consistently meet the criterion for sporicidal activity after 10 min (data not shown). Extending the contact time to 20 min allowed both levels of PAA and DB to meet the criterion for sporicidal activity, while 500 ppm of CD failed to do so; CD at 1,000 ppm barely met the criterion when tested alone against the spores but could not do so in the mixture (Fig. (Fig.11).Open in a separate windowFIG. 1.Reductions of G. stearothermophilus spores by the test formulations after 20 min of contact, individually and in a mixture at 22 ± 2°C.

TABLE 2.

Reductions by the test formulations in 5 min at 22 ± 2°C when tested against each organism individually and in a mixture
Disinfectant (concn [ppm])Mean log10 reduction ± SD of:
M. terrae
A. baumannii
G. stearothermophilus
Hepatitis A virus
IndividualMixtureIndividualMixtureIndividualMixtureIndividualMixture
Peracetic acid (500)8.18 ± 0.197.33 ± 0.167.19 ± 0.036.33 ± 0.034.03 ± 0.084.45 ± 0.98Not tested0.30 ± 0.01
Peracetic acid (1,000)8.18 ± 0.197.33 ± 0.167.19 ± 0.036.33 ± 0.038.03 ± 0.287.21 ± 0.590.58 ± 0.220.68 ± 0.09
Chlorine dioxide (500)8.18 ± 0.197.72 ± 0.217.22 ± 0.036.37 ± 0.131.47 ± 0.450.69 ± 0.054.30 ± 0.183.97 ± 0.19
Chlorine dioxide (1,000)8.18 ± 0.197.72 ± 0.217.22 ± 0.036.37 ± 0.133.07 ± 0.091.27 ± 0.054.30 ± 0.183.97 ± 0.19
Domestic bleach (2,500)8.18 ± 0.197.72 ± 0.217.22 ± 0.036.37 ± 0.130.27 ± 0.030.25 ± 0.024.41 ± 0.233.97 ± 0.29
Domestic bleach (3,500)8.18 ± 0.197.72 ± 0.217.22 ± 0.036.37 ± 0.130.27 ± 0.030.25 ± 0.024.41 ± 0.233.45 ± 0.09
Domestic bleach (5,000)8.18 ± 0.197.72 ± 0.217.22 ± 0.036.37 ± 0.130.28 ± 0.010.25 ± 0.024.41 ± 0.233.97 ± 0.29
Open in a separate windowThe study showed the feasibility of testing liquid chemicals against a mixture of suitable surrogates for infectious bioagents. This approach allowed standardized and simultaneous assessment of the spectrum of microbicidal activities of the test formulations under identical conditions that better simulate field conditions and that can be readily adapted to test foams and gaseous chemicals on other carrier materials. The surrogates selected covered the spectrum of microbicide resistances of all currently known classes of infectious bioagents.A. baumannii is among the more environmentally stable and microbicide-resistant vegetative bacteria known (7, 13). M. terrae represented pathogens with generally higher resistance to microbicides (3) and possibly drug-resistant Mycobacterium tuberculosis and category C agents (6). HAV, a small, nonenveloped virus known for its stability and microbicide resistance (9), represented select agents (CBW, biological weapons classification, 2001 [http://www.selectagents.gov/Select%20Agents%20and%20Toxins%20List.html]) and also food- and waterborne pathogens listed as biothreats (2, 10). The spores of G. stearothermophilus may be more resistant to oxidizing chemicals than the spores of Bacillus anthracis (8); their thermophilic nature made them safer to handle and easy to separate from the mixtures.The disinfectants were selected for their commercial availability and broad-spectrum and relatively rapid action (5, 14). The last criterion excluded all but oxidizers because other common active agents are limited as microbicides and/or require hours of contact for sporicidal action.For PAA tests, the recovery of infectious HAV in the absence of any viable spores is somewhat anomalous but not surprising. While we do not believe HAV to be more resistant than bacterial spores, the small size of the virus in the dried inocula likely afforded it significant protection. Compared to HAV, the mycobacterium proved more susceptible to all the disinfectants tested. This highlights a serious weakness in the traditional rankings of disinfectant susceptibility, where mycobacteria are often considered more resistant than nonenveloped viruses (5, 14).In the initial trials with the mixtures, the titer of A. baumannii dropped sharply; using virus pools without antibiotics resolved the issue. The ability of A. baumannii to grow on 7H11 agar and thus interfere with the recovery of M. terrae was addressed by replacing the standard strain of M. terrae with one containing a kanamycin resistance gene (15). Incorporation of enough kanamycin in 7H11 suppressed the growth of A. baumannii while allowing the mycobacterium to grow.Using a mixture of surrogates in QCT not only proved feasible but also highlighted the need to review certain long-held concepts about the relative sensitivities of classes of pathogens to disinfectants. The details reported should allow extension of the work to CL-3 and possibly CL-4 agents to confirm that the results obtained with the carefully chosen surrogates are indeed applicable to various classes of infectious bioagents.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号