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1.
Ajai K. Tripathi Umed V. Ramani Amrutlal K. Patel Dharamshibhai N. Rank Chaitanya G. Joshi 《Applied biochemistry and biotechnology》2013,169(2):688-694
Myostatin (MSTN) belongs to the transforming growth factor (TGF)-β superfamily and is a potent negative regulator of skeletal muscle development and growth. Dysfunction of MSTN gene either by natural mutation or induced through genetic manipulation (knockout or knockdown) has been reported to increase the remarkable muscle mass in mammalian species. RNA interference (RNAi) is the most promising method for inhibition of gene expression that can be utilized for MSTN gene knockdown by developing short hairpin RNA (shRNA) construct against it. We utilized three antisense RNA expressing vectors with six constructs to knockdown MSTN gene in in vitro caprine myoblast cell culture system. We observed that all six shRNA constructs were successful in MSTN silencing with efficiency ranging from 7 to 46 % by quantitative real-time PCR and up to 19 % by western blotting. The significant upregulation of interferon response gene OAS1 (5- to 11-fold) in cells transfected with shRNA constructs were indicative of induction of interferon response. This RNAi-based method of increasing muscle mass could provide an alternative strategy to gene knockout methods for improving the production traits and economic properties of livestock. 相似文献
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Elena Genova Maura Apollonio Giuliana Decorti Alessandra Tesser Alberto Tommasini Gabriele Stocco 《Molecules (Basel, Switzerland)》2021,26(12)
Interferonopathies are rare genetic conditions defined by systemic inflammatory episodes caused by innate immune system activation in the absence of pathogens. Currently, no targeted drugs are authorized for clinical use in these diseases. In this work, we studied the contribution of sulforaphane (SFN), a cruciferous-derived bioactive molecule, in the modulation of interferon-driven inflammation in an immortalized human hepatocytes (IHH) line and in two healthy volunteers, focusing on STING, a key-component player in interferon pathway, interferon signature modulation, and GSTM1 expression and genotype, which contributes to SFN metabolism and excretion. In vitro, SFN exposure reduced STING expression as well as interferon signature in the presence of the pro-inflammatory stimulus cGAMP (cGAMP 3 h vs. SFN+cGAMP 3 h p value < 0.0001; cGAMP 6 h vs. SFN+cGAMP 6 h p < 0.001, one way ANOVA), restoring STING expression to the level of unstimulated cells. In preliminary experiments on healthy volunteers, no appreciable variations in interferon signature were identified after SFN assumption, while only in one of them, presenting the GSTM1 wild type genotype related to reduced SFN excretion, could a downregulation of STING be recorded. This study confirmed that SFN inhibits STING-mediated inflammation and interferon-stimulated genes expression in vitro. However, only a trend towards the downregulation of STING could be reproduced in vivo. Results obtained have to be confirmed in a larger group of healthy individuals and in patients with type I interferonopathies to define if the assumption of SFN could be useful as supportive therapy. 相似文献
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Rebecca L. Hartman Nathalie A. Desrosiers Allan J. Barnes Keming Yun Karl B. Scheidweiler Erin A. Kolbrich-Spargo David A. Gorelick Robert S. Goodwin Marilyn A. Huestis 《Analytical and bioanalytical chemistry》2014,406(2):587-599
3,4-Methylenedioxymethamphetamine (MDMA) is an illicit phenethylamine ingested for entactogenic and euphoric effects. Although blood is more commonly submitted for forensic analysis, previous human MDMA pharmacokinetics research focused on plasma data; no direct blood–plasma comparisons were drawn. Blood and plasma specimens from 50 healthy adult volunteers (33 males, 17 females, 36 African-American) who ingested recreational 1.0 and 1.6 mg/kg MDMA doses were quantified for MDMA and metabolites 4-hydroxy-3-methoxymethamphetamine (HMMA), 3,4-methylenedioxyamphetamine (MDA), and 4-hydroxy-3-methoxyamphetamine (HMA) by two-dimensional gas chromatography–mass spectrometry. Specimens were collected up to 3 h post-dose and evaluated for maximum concentration (C max), first detection time (t first), time of C max (t max), and 3-h area under the curve (AUC0–3 h); as well as blood metabolite ratios and blood/plasma ratios. Median blood MDMA and MDA C max were significantly greater (p?<?0.0005) than in plasma, but HMMA was significantly less (p?<?0.0005). HMA was detected in few blood specimens, at low concentrations. Nonlinear pharmacokinetics were not observed for MDMA or MDA in this absorptive phase, but HMMA C max and AUC0–3 h were similar for both doses despite the 1.6-fold dose difference. Blood MDA/MDMA and MDA/HMMA significantly increased (p?<?0.0001) over the 3-h time course, and HMMA/MDMA significantly decreased (p?<?0.0001). Blood MDMA C max was significantly greater in females (p?=?0.010) after the low dose only. Low-dose HMMA AUC0–3 h was significantly decreased in females’ blood and plasma (p?=?0.027) and in African-Americans’ plasma (p?=?0.035). These data provide valuable insight into MDMA blood–plasma relationships for forensic interpretation and evidence of sex- and race-based differential metabolism and risk profiles. Figure
Median (interquartile range) blood/plasma 3,4-methylenedioxymethamphetamine (MDMA) (a), 4-hydroxy-3-methoxymethamphetamine (HMMA) (b), and 3,4-methylenedioxyamphetamine (MDA) (c) ratios for 3 h after controlled MDMA administration. Changes over time were significant after the 1.6 mg/kg dose for HMMA and MDA (p?=?0.013 and p?=?0.021), but not for MDMA. No changes over time were significant after the 1.0 mg/kg dose. Note: y-axes do not begin at 0. *p ?<?0.05 (low vs. high) 相似文献
5.
Ya-Ching Hsu Bud-Gen Chen Shu-Ching Yang Yu-Shan Wang Shiao-Ping Huang Mei-Han Huang Tai-Jui Chen Hsu-Chun Liu Dong-Liang Lin Ray H. Liu A. Wayne Jones 《Analytical and bioanalytical chemistry》2013,405(12):3921-3928
Methadone (MTD) is widely used for detoxification of heroin addicts and also in pain management programs. Information about the distribution of methadone between blood, plasma, and alternative specimens, such as oral fluid (OF), is needed in clinical, forensic, and traffic medicine when analytical results are interpreted. We determined MTD and its metabolite 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) in blood, plasma, blood cells, and OF by gas chromatography–mass spectrometry (GC-MS) after adding deuterium-labeled internal standards. The analytical limits of quantitation for MTD and EDDP by this method were 20 and 3 ng/mL, respectively. The amounts of MTD and EDDP were higher in plasma (80.4 % and 76.5 %) compared with blood cells (19.6 % and 23.5 %) and we found that repeated washing of blood cells with phosphate–buffered saline increased the amounts in plasma (93.6 % and 88.6 %). Mean plasma/blood concentration ratios of MTD and EDDP in spiked samples (N?=?5) were 1.27 and 1.21, respectively. In clinical samples from patients (N?=?46), the concentrations of MTD in plasma and whole blood were highly correlated (r?=?0.92, p?<?0.001) and mean (median) plasma/blood distribution ratios were 1.43 (1.41). The correlations between MTD in OF and plasma (r?=?0.46) and OF and blood (r?=?0.52) were also statistically significant (p?<?0.001) and the mean OF/plasma and OF/blood distribution ratios were 0.55 and 0.77, respectively. The MTD concentration in OF decreased as salivary pH increased (more basic). These results will prove useful in clinical and forensic medicine when MTD concentrations in alternative specimens are compared and contrasted. 相似文献
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Vel Berzin Michael Kiriukhin Michael Tyurin 《Applied biochemistry and biotechnology》2012,168(6):1384-1393
Acetogen strain Clostridium sp. MT1121 produced 300?mM acetate (p?<?0.005) and 321?mM ethanol (p?<?0.005) from synthesis gas (syngas) blend 60?% CO and 40?%?H2. Clostridium sp. MT1121 was metabolically engineered to eliminate production of either acetate or acetaldehyde during syngas fermentation. We used Cre-lox66/lox71-based gene removal system to eliminate either phosphotransacetylase (pta), or acetaldehyde dehydrogenase (aldh). The resulted biocatalyst with eliminated pta increased ethanol yield to 610?mM (p?<?0.005). Inactivation of pta rendered only 502?mM of ethanol (p?<?0.005). The acetogen biocatalyst with eliminated aldh produced 450?mM acetate (p?<?0.005). The role of cell energy pool preservation for re-directed carbon flux is discussed. This is the first report on time- and cost-efficient gene elimination in acetogens using lox66/lox71 gene elimination system. 相似文献
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Saba Shahin Vineet Prakash Singh Ritesh K. Shukla Alok Dhawan Ravi Kumar Gangwar Surya Pal Singh Chandra Mohini Chaturvedi 《Applied biochemistry and biotechnology》2013,169(5):1727-1751
The present experiment was designed to study the 2.45 GHz low-level microwave (MW) irradiation-induced stress response and its effect on implantation or pregnancy in female mice. Twelve-week-old mice were exposed to MW radiation (continuous wave for 2 h/day for 45 days, frequency 2.45 GHz, power density?=?0.033549 mW/cm2, and specific absorption rate?=?0.023023 W/kg). At the end of a total of 45 days of exposure, mice were sacrificed, implantation sites were monitored, blood was processed to study stress parameters (hemoglobin, RBC and WBC count, and neutrophil/lymphocyte (N/L) ratio), the brain was processed for comet assay, and plasma was used for nitric oxide (NO), progesterone and estradiol estimation. Reactive oxygen species (ROS) and the activities of ROS-scavenging enzymes— superoxide dismutase, catalase, and glutathione peroxidase—were determined in the liver, kidney and ovary. We observed that implantation sites were affected significantly in MW-irradiated mice as compared to control. Further, in addition to a significant increase in ROS, hemoglobin (p?<?0.001), RBC and WBC counts (p?<?0.001), N/L ratio (p?<?0.01), DNA damage (p?<?0.001) in brain cells, and plasma estradiol concentration (p?<?0.05), a significant decrease was observed in NO level (p?<?0.05) and antioxidant enzyme activities of MW-exposed mice. Our findings led us to conclude that a low level of MW irradiation-induced oxidative stress not only suppresses implantation, but it may also lead to deformity of the embryo in case pregnancy continues. We also suggest that MW radiation-induced oxidative stress by increasing ROS production in the body may lead to DNA strand breakage in the brain cells and implantation failure/resorption or abnormal pregnancy in mice. 相似文献
9.
Nathalie A. Desrosiers Allan J. Barnes Rebecca L. Hartman Karl B. Scheidweiler Erin A. Kolbrich-Spargo David A. Gorelick Robert S. Goodwin Marilyn A. Huestis 《Analytical and bioanalytical chemistry》2013,405(12):4067-4076
Oral fluid (OF) offers a noninvasive sample collection for drug testing. However, 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) in OF has not been adequately characterized in comparison to plasma. We administered oral low-dose (1.0 mg/kg) and high-dose (1.6 mg/kg) MDMA to 26 participants and collected simultaneous OF and plasma specimens for up to 143 h after dosing. We compared OF/plasma (OF/P) ratios, time of initial detection (t first), maximal concentrations (C max), time of peak concentrations (t max), time of last detection (t last), clearance, and 3,4-methylenedioxyamphetamine (MDA)-to-MDMA ratios over time. For OF MDMA and MDA, C max was higher, t last was later, and clearance was slower compared to plasma. For OF MDA only, t first was later compared to plasma. Median (range) OF/P ratios were 5.6 (0.1–52.3) for MDMA and 3.7 (0.7–24.3) for MDA. OF and plasma concentrations were weakly but significantly correlated (MDMA: R 2?=?0.438, MDA: R 2?=?0.197, p?<?0.0001). Median OF/P ratios were significantly higher following high dose administration: MDMA low?=?5.2 (0.1–40.4), high?=?6.0 (0.4–52.3, p?<?0.05); MDA low?=?3.3 (0.7–17.1), high?=?4.1 (0.9–24.3, p?<?0.001). There was a large inter-subject variation in OF/P ratios. The MDA/MDMA ratios in plasma were higher than those in OF (p?<?0.001), and the MDA/MDMA ratios significantly increased over time in OF and plasma. The MDMA and MDA concentrations were higher in OF than in plasma. OF and plasma concentrations were correlated, but large inter-subject variability precludes the estimation of plasma concentrations from OF. Figure
Oral fluid and plasma 3,4-methylenedioxymethamphetamine (MDMA) concentrations in all simultaneously collected paired-positive specimens collected ?0.25 to 143 h after 1.0 and 1.6 mg/kg oral MDMA administration to 26 adult participants 相似文献
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Vel Berzin Michael Tyurin Michael Kiriukhin 《Applied biochemistry and biotechnology》2013,169(3):950-959
Acetogen Clostridum sp. MT1962 produced 287 mM acetate (p?<?0.005) and 293 mM ethanol (p?<?0.005) fermenting synthesis gas blend 60 % CO and 40 %?H2 in single-stage continuous fermentation. This strain was metabolically engineered to the biocatalyst Clostridium sp. MTButOH1365. The engineered biocatalyst lost production of ethanol and acetate while initiated the production of 297 mM of n-butanol (p?<?0.005). The metabolic engineering comprised Cre-lox66/lox71-based elimination of phosphotransacetylase and acetaldehyde dehydrogenase along with integration to chromosome synthetic thiolase, 3-hydroxy butyryl-CoA dehydrogenase, crotonase, butyryl-CoA dehydrogenase, butyraldehyde dehydrogenase, and NAD-dependent butanol dehydrogenase. This is the first report on elimination of acetate and ethanol production genes and expression of synthetic gene cluster encoding n-butanol biosynthesis pathway in acetogen biocatalyst for selective fuel n-butanol production with no antibiotic support for the introduced genes. 相似文献
11.
S. Ya. Istomin E. V. Antipov Yu. S. Fedotov S. I. Bredikhin N. V. Lyskov S. Shafeie G. Svensson Y. Liu Z. Shen 《Journal of Solid State Electrochemistry》2014,18(5):1415-1423
Novel complex oxides Sr2Ga1+x In1?x O5, x?=?0.0–0.2 with brownmillerite-type structure were prepared in air at T?=?1,273 K, 24 h. Study of the crystal structure of Sr2Ga1.1In0.9O5 refined using X-ray powder diffraction data (S.G. Icmm, a?=?5.9694(1) Å, b?=?15.2091(3) Å, c?=?5.7122(1) Å, χ 2?=?2.48, R F 2? =?0.0504, R p?=?0.0458) revealed ordering of Ga3+ and In3+ cations over tetrahedral and octahedral positions, respectively. A partial replacement of Sr2+ by La3+ according to formula Sr1?y La y Ga0.5In0.5O2.5+y/2, leads to the formation of a cubic perovskite (a?=?4.0291(5) Å) for y?=?0.3. No ordering of oxygen vacancies or cations was observed in Sr0.7La0.3Ga0.5In0.5O2.65 as revealed by electron diffraction study. The trace diffusion coefficient (D T) of oxygen for cubic perovskite Sr0.7La0.3Ga0.5In0.5O2.65 is in the range 2.0?×?10?9–6.3?×?10?8 cm2/s with activation energy 1.4(1)?eV as determined by isotopic exchange depth profile technique using secondary ion mass spectrometry at 973–1,223 K. These values are close to those reported for Ca-doped ZrO2. High-temperature electrical conductivity of Sr0.7La0.3Ga0.5In0.5O2.65 studied by AC impedance was found to be nearly independent on oxygen partial pressure. Calculated values of activation energy at T?<?1,073 K for hole and oxide-ion conductivities are 0.96 and 1.10 eV, respectively. 相似文献
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A. S. Pradeep G. J. Nagaraju P. Sarita A. Durga Prasada Rao B. Seetharami Reddy G. Bhagya Rao S. Bhuloka Reddy 《Journal of Radioanalytical and Nuclear Chemistry》2012,294(2):271-276
A number of essential trace elements play a major role in various metabolic pathways and in many diseases like autoimmune, neurological and psychiatric. This study is undertaken with an aim to evaluate the levels of different trace elements in the scalp hair samples of patients suffering from alcohol induced psychosis by particle induced X-ray emission technique (PIXE). It is observed that Fe (p?<?0.0005), Cu (p?<?0.001) are significantly higher in the hair samples of alcohol induced psychosis patients compared to those in normals while concentrations of Mn (p?<?0.005) and Zn (p?<?0.0001) are lower. The concentrations of Co and Ni in the hair samples are found to be in consonance with the concentrations in the normals. 相似文献
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Amaneh Javid Shahin Ahmadian Ali Akbar Saboury Seyed Mehdi Kalantar Saeed Rezaei-Zarchi Sughra Shahzad 《Applied biochemistry and biotechnology》2014,173(1):36-54
Magnetite nanoparticles are particularly attractive for drug delivery applications because of their size-dependent superparamagnetism, low toxicity, and biocompatibility with cells and tissues. Surface modification of iron oxide nanoparticles with biocompatible polymers is potentially beneficial to prepare biodegradable nanocomposite-based drug delivery agents for in vivo and in vitro applications. In the present study, the bare (10 nm) and polyethylene glycol (PEG)–(3-aminopropyl)triethoxysilane (APTES) (PA) modified (17 nm) superparamagnetic iron oxide nanoparticles (SPIO NPs) were synthesized by coprecipitation method. The anticancer drugs, doxorubicin (DOX) and paclitaxel (PTX), were separately encapsulated into the synthesized polymeric nanocomposites for localized targeting of human ovarian cancer in vitro. Surface morphology analysis by scanning electron microscopy showed a slight increase in particle size (27?±?0.7 and 30?±?0.45 nm) with drug loading capacities of 70 and 61.5 % and release capabilities of 90 and 93 % for the DOX- and PTX-AP-SPIO NPs, respectively (p?<?0.001). Ten milligrams/milliliter DOX- and PTX-loaded AP-SPIO NPs caused a significant amount of cytotoxicity and downregulation of antiapoptotic proteins, as compared with same amounts of free drugs (p?<?0.001). In vivo antiproliferative effect of present formulation on immunodeficient female Balb/c mice showed ovarian tumor shrinkage from 2,920 to 143 mm3 after 40 days. The present formulation of APTES–PEG-SPIO-based nanocomposite system of targeted drug delivery proved to be effective enough in order to treat deadly solid tumor of ovarian cancer in vitro and in vivo. 相似文献
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Vel Berzin Michael Kiriukhin Michael Tyurin 《Applied biochemistry and biotechnology》2012,167(2):338-347
Acetogen strain Clostridum sp. MT653 produced acetate 273?mM (p?<?0.005) and ethanol 250?mM (p?<?0.005) from synthesis gas blend mixture of 64?% CO and 36?%?H2. Clostridum sp. MT653 was metabolically engineered to the biocatalyst strain Clostridium sp. MTEtOH550. The biocatalyst increased ethanol yield to 590?mM with no acetate production during single-stage continuous syngas fermentation due to expression of synthetic adh cloned in a multi-copy number expression vector. The acetate production was eliminated by inactivation of the pta gene in Clostridium sp. MTEtOH550. Gene introduction and gene elimination were achieved only using Syngas Biofuels Energy, Inc. electroporation generator. The electrotransformation efficiencies were 8.0?±?0.2?×?106 per microgram of transforming DNA of the expression vector at cell viability ~15?%. The frequency of suicidal vector integration to inactivate pta was ~10?5 per the number of recipient cells. This is the first report on elimination of acetate production and overexpression of synthetic adh gene to engineer acetogen biocatalyst for selective biofuel ethanol production during continuous syngas fermentation. 相似文献
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Y. H. Ren F. Q. Zhao J. H. Yi K. Z. Xu H. X. Ma R. Z. Hu J. R. Song 《Journal of the Iranian Chemical Society》2012,9(3):407-414
A new ionic compound (3-ATz)+ (NTO)?C was synthesized by the reaction of 3-amino-1,2,4-triazole (3-ATz) with 3-nitro-1,2,4-triazol-5-one (NTO) in ethanol. The single crystals suitable for X-ray diffraction measurement were obtained by crystallization at room temperature. The crystal is monoclinic, space group p 2(1)/c with crystal parameters of a?=?0.6519(2)?nm, b?=?1.9075(7)?nm, c?=?0.6766(2)?nm, ???=?94.236(4)°, R 1?=?0.0305 and wR 2?=?0.0789. The thermal behaviors were studied, and the apparent activation energy and pre-exponential constant of the exothermic decomposition stage were obtained by Kissinger??s method and Ozawa??s method. The self-accelerating decomposition temperature is 505.40?K, and the critical temperature of the thermal explosion is obtained as 524.90?K. The specific heat capacity was determined with Micro-DSC method and the theoretical calculation method, and the standard molar specific heat capacity is 221.31?J?mol?1?K?1 at 298.15?K. The Gibbs free energy of activation, enthalpy of activation, and entropy of activation are 151.55?kJ?mol?1, 214.52?kJ?mol?1 and 122.44?J?mol?1?K?1. The adiabatic time-to-explosion of the compound was estimated to be a certain value between 5.0 and 5.2?s, and the detonation velocity (D) and pressure (P) were also estimated using the nitrogen equivalent equation according to the experimental density. 相似文献
17.
Victor Starov 《Colloid and polymer science》2013,291(2):261-270
A theory of contact angle hysteresis on smooth, homogeneous solid substrates is developed in terms of shape of disjoining/conjoining pressure isotherm and quasi-equilibrium phenomena. It is shown that all contact angles, θ, in the range θ r?<?θ?<?θ a, which are different from the unique equilibrium contact angle θ?≠?θ e, correspond to the state of slow “microscopic” advancing or receding motion of the liquid if θ e ?<?θ?<?θ a or θ r?<?θ?<?θ e, respectively. This “microscopic” motion almost abruptly becomes fast “macroscopic” advancing or receding motion after the contact angle reaches the critical values θ?=?θ a or θ r?=?θ, correspondingly. The values of the static receding, θ r, and static advancing, θ a, contact angles in cylindrical capillaries were calculated earlier, based on the shape of disjoining pressure isotherm. It is shown that an advancing contact angle of a droplet on a solid substrate depends on the drop volume and is not a unique characteristic of the liquid–solid system. The suggested mechanism of contact angle hysteresis has direct experimental confirmation. 相似文献
18.
Prasant Kumar Jena Shilpa Singh Bhumika Prajapati G. Nareshkumar Tejal Mehta Sriram Seshadri 《Applied biochemistry and biotechnology》2014,172(8):3810-3826
The objective of present investigation was to study the effect of gut microbiota alteration by oral administration of targeted delivery of pH sensitive cefdinir microspheres to high-fructose-fed (HFD) rats. Rats were fed with a high-fructose diet with or without cefdinir microsphere administration for 30 days. The fecal microbiota community, oral glucose tolerance, the markers of liver injury, plasma and hepatic lipids profile, and histological evaluation were investigated. The levels of blood glucose, liver injury markers, lipid profile in plasma and liver, and fat tissue were significantly increased in high-fructose-fed rats. However, after pH-sensitive cefdinir microsphere administration, the elevation of these parameters was significantly suppressed. Cef EL significantly lowered the increased AST (p?<?0.05) and ALT (p?<?0.001) levels in HFD group. There is a significant lower (p?<?0.01) AUCglucose level in Cef EL group than HFD group The histological changes in the liver and the small and large intestines were more profound in HFD group as compared to cefdinir-treated HFD and control groups. Feeding of cefdinir microsphere sustained lactobacilli and bifidobacteria and significantly decreased (p?<?0.05) the number of Enterobacteriaceae induced by HFD. Experimental evidences demonstrated that the effectiveness of pH-specific cefdinir microsphere on reducing insulin resistance and development of metabolic changes in high-fructose-fed rats and suggested that it may be a promising therapeutic agent in treating type 2 diabetes. Intestinal-targeted antibiotic delivery needs to be further explored for its therapeutic applications. 相似文献
19.
Effects of low-level gamma irradiation on the characteristics of fermented pork sausage during storage 总被引:1,自引:0,他引:1
I.S. KimC. Jo K.H. LeeE.J. Lee D.U. AhnS.N. Kang 《Radiation Physics and Chemistry》2012,81(4):466-472
The effect of gamma irradiation (0.5, 1, 2, and 4 kGy) on the quality of vacuum-packaged dry fermented sausages during refrigerated storage was evaluated. At Day 0 of irradiation, the pH, redness (CIE a?), yellowness (CIE b?), 2-thiobarbituric acid-reactive substances (TBARS) and volatile basic nitrogen (VBN) values of samples irradiated at 2 and 4 kGy were higher (p<0.05), but the CIE L? values (lightness) were lower than those of the non-irradiated control (p<0.05). At<1 kGy irradiation, however, the pH, CIE L?, CIE a? and CIE b?-value of samples were not significantly influenced by irradiation. The CIE a?, and CIE b?-values of samples irradiated at 2 and 4 kGy decreased with the increase of storage time. The VBN, TBARS, and CIE L?-values of samples irradiated at 4 kGy were not changed significantly during refrigerated storage for 90 days (p>0.05). The total plate counts (TPC) and lactic acid bacteria (LAB) in the samples irradiated at 4 kGy were significantly lower (p<0.01) than those with lower irradiation doses. At the end of storage, the TPC, coliform, and LAB in the samples were not increased after irradiation at 1, 0.5 and 1 kGy, respectively. TPC and LAB were not detected in samples irradiated at 4 kGy at Day 90. In addition, no coliform bacteria were found in samples irradiated at 1 kGy during refrigerated storage. Sensory evaluation indicated that the rancid flavor of samples irradiated at 4 kGy was significantly higher, but aroma and taste scores were lower than those of the control at Day 3 of storage. Irradiation of dry fermented sausages at 2 kGy was the best conditions to prolong the shelf-life and decrease the rancid flavor without significant quality deterioration. 相似文献
20.
Márta Kraszni Attila Marosi Cynthia K. Larive 《Analytical and bioanalytical chemistry》2013,405(17):5807-5816
In exploring the capability of nuclear magnetic resonance (NMR) spectroscopy for pomegranate juice analysis, the eight aromatic singlet resonances of α- and β-punicalagin were clearly identified in the 1H NMR spectra of juice samples. The four downfield resonances were found to be sensitive to small pH changes around pH 3.50 where the NMR spectra of the juice samples were recorded. To understand this unusual behavior, the 1H and 13C resonance assignments of the punicalagin anomers were determined in aqueous solution and pH titrations with UV and 1H NMR detection carried out to characterize the acid–base properties of punicalagin over the pH range 2–8. Simultaneous fitting of all of the pH-sensitive 1H NMR signals produced similar but significantly different pK a values for the first two deprotonation equilibria of the gallagic acid moiety of the punicalagin α- (pK a1?=?4.57?±?0.02, pK a2?=?5.63?±?0.03) and β- (pK a1?=?4.36?±?0.01, pK a2?=?5.47?±?0.02) anomers. Equivalent pK a values, (α?:?6.64?±?0.01, β?:?6.63±?0.01) were measured for the third deprotonation step involving the ellagic acid group, in good agreement with a prior literature report. The punicalagin anomer equilibrium readjusts in parallel with the proton dissociation steps as the pH is raised such that β-punicalagin becomes the most abundant anomer at neutral pH. The unusual upfield shifts observed for the glucose H3 and H5 resonances with increasing pH along with the shift in the α/β anomer equilibrium are likely the consequence of a conformational rearrangement. Figure
Titration of the punicalagin phenolate protons over the pH range 2–8 results in changes in the aromatic proton chemical shifts and a readjustment of the anomer equilibrium. 相似文献