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1.
Infrared absorption spectra for a number of polysaccharides and their nitrated derivatives have been obtained. The frequency range 730–960 cm?1 is useful for identification of the polysaccharides, and the region 900–1350 cm?1 is more suitable for distinguishing the nitrated materials. The strong intensity of the nitrate bands limits the interpretation of spectra below 960 cm?1, but above this frequency the absorption bands of nitrated polysaccharides are generally sharper and more clearly defined than the corresponding bands of the parent polysaccharides. Data on the COC bridge, CC ring, CO, and COH frequencies and on the CH deformation and stretching frequencies have been obtained. The use of i.r. spectroscopy for the quantitative determination of nitrate groups in nitrated polysaccharides is discussed.  相似文献   

2.
Summary We have investigated the short-term effects of hydrocortisone (60 mg/kg per day) and placebo on basal and stimulated pancreatic secretion in the conscious rat. Volume and enzyme secretion were determined; fine structural changes were examined simultaneously.The pancreatic and bile ducts were cannulated separately; pancreatic juice was drained via an isolated fistula, and bile was recirculated into the duodenum. The application of hydrocortisone led to an almost complete inhibition of the secretory response of the exocrine pancreas when stimulated with 0.25 U secretin in combination with 5 × 10-8 g caerulein per h. It strongly affected the secretion rates of volume, protein, lipase, chymotrypsin, trypsin and carboxypeptidase, whereas the secretion rate of alpha-amylase continued to show a slight increase after stimulation.After stimulation with secretin and caerulein, the hydrocortisone-treated animals showed a higher density of zymogen granules in the acinar cell and an increase in the number of autophagic vacuoles in comparison to the equally stimulated placebo-treated rats.It is concluded that the short-term inhibition of pancreatic secretion by hydrocortisone occurs largely as a result of an inhibition of cellular enzyme discharge.Supported by the Deutsche Forschungsgemeinschaft, Ga 279  相似文献   

3.
4.
Aims: The purpose of this study was to investigate the efficacy of continuous ohmic heating for reducing Escherichia coli O157:H7, Salmonella Typhimurium and Listeria monocytogenes in orange juice and tomato juice. Methods and Results: Orange juice and tomato juice were treated with electric field strengths in the range of 25–40 V cm?1 for different treatment times. The temperature of the samples increased with increasing treatment time and electric field strength. The rate of temperature change for tomato juice was higher than for orange juice at all voltage gradients applied. Higher electric field strength or longer treatment time resulted in a greater reduction of pathogens. Escherichia coli O157:H7 was reduced by more than 5 log after 60‐, 90‐ and 180‐s treatments in orange juice with 40, 35 and 30 V cm?1 electric field strength, respectively. In tomato juice, treatment with 25 V cm?1 for 30 s was sufficient to achieve a 5‐log reduction in E. coli O157:H7. Similar results were observed in Salm. Typhimurium and L. monocytogenes. The concentration of vitamin C in continuous ohmic heated juice was significantly higher than in conventionally heated juice (P < 0·05). Conclusions: Continuous ohmic heating can be effective in killing foodborne pathogens on orange juice and tomato juice with lower degradation of quality than conventional heating. Significance and Impact of the Study: These results suggest that continuous ohmic heating might be effectively used to pasteurize fruit and vegetable juices in a short operating time and that the effect of inactivation depends on applied electric field strengths, treatment time and electric conductivity.  相似文献   

5.
Bile and pancreatic juice vary in their trypsin inhibitor content. Activation of bile-pancreatic juice mixtures (1:1) occurred when the combined trypsin inhibitory capacity was low. No activation was seen with bile having a high trypsin inhibitor content. Pancreatic juice activated faster where more trypsin inhibitor complex was present. With calcium (25 mM), pancreatic secretions activated in a similar order as with the trypsin-inhibitor-free bile. We propose that activation occurs more readily where large amounts of the trypsin-inhibitor complex are present in pancreatic juice as a result of carcinoma or other etiologies.  相似文献   

6.
The i.r. spectra for aqueous solutions of sulfated glycosaminoglycans and model compounds in the transmittance “window” region of the solvent (1400-950 cm?1) are dominated by the strong and complex absorption centered at ~1230 cm?1 and associated with the antisymmetric stretching vibrations of the SO groups. Primary and secondary O-sulfate groups absorb at somewhat higher frequencies (1260-1200 cm?1) than N-sulfates (~1185 cm?1). Each sulfate band lends itself to quantitative applications, especially within a given class of sulfated polysaccharide. Laser-Raman spectra of heparin and model compounds have been obtained in aqueous solution and in the solid state. The most-prominent Raman peak (at ~1060 cm?1) is attributable to the symmetrical vibration of the SO groups, with N-sulfates emitting at somewhat lower frequencies (~1040 cm?1) than O-sulfates. The Raman pattern in the 950-800 cm?1 region (currently used in the i.r. for distinguishing between types of sulfate groups) also involves vibrations that are not localized only in the COS bonds.  相似文献   

7.
Impurity injection into plasma caused by the sputtering of the wall coating in the L-2M stellarator during auxiliary electron cyclotron resonance heating leads to a change in the level of plasma density fluctuations with frequencies above 0.25 MHz: suppression of long-wavelength (k = 2 cm–1) density fluctuations in the edge plasma, intensification of short-wavelength (k = 30 cm–1) and long-wavelength (k = 1 cm–1) fluctuations at the midradius of the plasma column, and intensification of short-wavelength fluctuations (k = 20 cm–1) in the plasma center (including the gyroresonance region). At the same time, the level of fluctuations with frequencies below 0.25 MHz remains unchanged. In the edge plasma, a decrease in the plasma potential and suppression of its fluctuations is observed during impurity injection, which also causes an increase in MHD activity.  相似文献   

8.
1. The secretory responses of bile and exocrine pancreas were studied in various aged piglets. 2. At 3 days old the bile and exocrine pancreas could be reacted by various stimulations. The response by secretin was the same as that in the 28 day old. 3. Protein concentration in pancreatic juice by CCK-8 increased steeply after 6 days old, but the ratio of amylase to protein rose abruptly at 28 days old. 4. These findings indicate that (1) the secretory capacity of bile and pancreatic juice developed predominantly at an early period of postnatal life; (2) the formation of bile acids and pancreatic digestive enzymes developed gradually during the suckling period.  相似文献   

9.
Raman studies of conformational changes in model membrane systems   总被引:2,自引:0,他引:2  
Laser Raman spectra of concentrated samples of phosphatidyl choline and phosphatidyl ethanolamine were taken at approximately 10° intervals over a temperature range of 90°–19°C. The spectral region from 30 to 3300 cm?1 was investigated. Several new spectral features were discovered which are correlated to phospholipid liquid crystalline structure. It is shown that 1) frequency shifts occur in the PO2? symmetric stretch band which suggest a change in exposure of the PO2 group to the solvent upon melting, 2) the frequency of the translational hydrocarbon mode around 150 cm?1 appears to indicate the degree to which the hydrocarbon chain is extended, 3) the methyl and methylene stretch bands at 2890 and 2850 cm?1 very clearly demonstrate hydrocarbon chain melting, and 4) the 720 cm?1 band, previously assigned to the symmetric OPO diester stretch, appears to be due instead to the symmetric CN stretch of choline.  相似文献   

10.
The effect of continuous ultrasonic treatment on the development of early embryos of common frog Rana temporaria was studied. Intact embryos at the blastula stage were exposed to ultrasound of various frequencies (0.88 and 2.64 MHz) and intensities (0.05 to 1.0 W/cm2) for various periods (1 to 15 min). The increase in ultrasound intensity to 0.7–1.0 W/cm2 and exposure time to 5–15 min resulted in nearly complete mortality. Development of the embryos exposed to ultrasound of medium intensity (0.2–0.7 W/cm2) for 1–5 min was virtually similar to the control. Treatment at a frequency of 2.64 MHz and intensity of 0.05–0.7 W/cm2 for 1–5 min had no effect on the development of amphibian embryos and their survival rate. The increase in intensity of the ultrasound of this frequency to 1 W/cm2 and the exposure time to 5 min decreased the number of normally developing embryos by 35%.  相似文献   

11.
The aim of this study was to determine the resistance mechanisms of chili induced by the Bacillus subtilis strain D604 using synchrotron FTIR microspectroscopy (SR-FTIR). In this study, the strain D604 reduced anthracnose disease severity in chili plants by approximately 31.10%. The SR-FTIR spectral changes from the epidermis and mesophyll leaf tissue revealed higher integral areas for the C=O ester from lipids, lignin, or pectin (1770–1700?cm?1) as well as polysaccharides (1200–900?cm?1) in the treated samples of D606 and distilled water and then challenge inoculation with chili anthracnose pathogen, Colletotrichum acutatum. The secondary structure of the Amide I protein failed to convert from alpha helices (centered at 1650?cm?1) to beta sheets (centered at 1600?cm?1) in the mesophyll of samples not treated with D604. This study suggested that the strain D604 induced resistance against anthracnose pathogen in chili by inducing cellular changes related to defense compounds involved in plant defense mechanism.  相似文献   

12.
The structure of sodium salts of arabinogalactan (AG) sulfates obtained by sulfating AG of larch wood with a sulfamic acid–urea mixture in 1,4-dioxane was studied by the methods of Raman spectroscopy, X-ray diffraction (XRD) phase analysis, scanning electron microscopy (SEM), and atomic force microscopy (AFM). The introduction of sulfate groups into the structure of arabinogalactan was confirmed by the appearance in the Raman spectra of new absorption bands related to the deformation vibrations δ (SO3) at 420 cm–1 and δ (О=S=O) at 588 cm–1, stretching vibrations ν (C–O–S) at 822 cm–1, symmetrical stretching vibrations νs (O=S=O) at 1076 cm–1, and asymmetric stretching vibrations of νas (O=S=O) at 1269 cm–1. According to the XRD data, the amorphization of arabinogalactan structure occurs during the sulfation process. The SEM method revealed a significant difference in the morphology of the sulfated and starting arabinogalactan. The starting AG consists of particles of predominantly globular shape with a size of 10 to 90 μm; arabinogalactan sulfates, of particles of various shapes with sizes of 1–8 μm. According to the AFM, the surface of sulfated arabinogalactan film consists of rather homogeneous spherical particles about 70 nm in size. The root-mean-square value of the surface roughness is 33 nm. The surface of sulfated AG film does not contain impurities.  相似文献   

13.
Laser-Raman spectra of L-α-dimyristoylphosphatidylcholine (DMPC) liposomes in the spectral range 1000–1200 cm?1 were obtained as a function of temperature from ?80 to +50°C. The triplet found in this spectral region was resolved into Lorentzian components by means of an iterative computer program. The peak intensities, band widths, and band areas of the resolved 1062 cm?1 and 1130 cm?1 bands, assigned to CC stretching vibrations of trans segments, were evaluated as a function of temperature. While the peak intensities of the bands decrease substantially with temperature, the band widths show a considerable increase. The change in band areas is therefore smaller than the change in peak heights. Experiments with all trans carboxylic acids showed that in these compounds the area of the Raman bands at 1062 cm?1 and 1130 cm?1 is proportional to the number of trans bonds. The variation with temperature of the number of trans and gauche bonds in the studied phospholipid is reflected by the change of the area of the 1130 cm?1 Raman band.  相似文献   

14.
New experimental data on the laser irradiation of low-density porous materials in the Mishen facility are presented and discussed. A wide set of optical and X-ray diagnostics was used to analyze the physical processes in porous media with different microstructures and specific densities of 1–30 mg/cm3 exposed to laser pulses with λ=1.054 µm, τ=3 ns, and I=1013–1014 W/cm2. The features of laser absorption and scattering and the processes of energy transfer in porous media were investigated for different average densities, thicknesses, and microstructures of the targets and different incidence angles of the laser beam. It was found that the material microstructure (chaotic or quasi-ordered) significantly affected the formation and dynamics of a plasma produced inside the irradiated samples that model the components of the advanced targets used in inertial confinement fusion research.  相似文献   

15.
The aim of this paper is to review and discuss the results obtained by fluorescence and absorption spectroscopy of bacterial chromatophores excited with picosecond pulses of varying power and intensity. It was inferred that spectral and kinetic characteristics depend essentially on the intensity, the repetition rate of the picosecond excitation pulses as well as on the optical density of the samples used. Taking the different experimental conditions properly into account, most of the discrepancies between the fluorescence and absorption measurements can be solved. At high pulse repetition rate (>106 Hz), even at moderate excitation intensities (1010–1011 photons/cm2 per pulse), relatively long-lived triplet states start accumulating in the system. These are efficient (as compared to the reaction centers) quenchers of mobile singlet excitations due to singlet-triplet annihilation. The singlet-triplet annihilation rate constant in Rhodospirillum rubrum was determined to be equal to 10-9 cm3 s-1. At fluences >1012 photons/cm2 per pulse singlet-singlet annihilation must be taken into account. Furthermore, in the case of high pulse repetition rates, triplet-triplet annihilation must be considered as well. From an analysis of experimental data it was inferred that the singlet-singlet annihilation process is probably migration-limited. If this is the case, one has to conclude that the rate of excitation decay in light-harvesting antenna at low pumping intensities is limited by the efficiency of excitation trapping by the reaction center. The influence of annihilation processes on spectral changes is also discussed as is the potential of a local heating caused by annihilation processes. The manifestation of spectral inhomogeneity of light-harvesting antenna in picosecond fluorescence and absorption kinetics is analyzed.Abbreviations LHA light-harvesting antenna - RC reaction center  相似文献   

16.
This article examines the applicability of Fourier Transform Infrared (FTIR) spectroscopy to detect the applied virus medium volume (i.e., during sample filling), to evaluate the virus state and to distinguish between different vaccine doses in a freeze dried live, attenuated vaccine formulation. Therefore, different formulations were freeze dried after preparing them with different virus medium volumes (i.e., 30, 100, and 400 µl) or after applying different pre‐freeze‐drying sample treatments (resulting in different virus states); i.e., (i) as done for the commercial formulation; (ii) samples without virus medium (placebo); (iii) samples with virus medium but free from antigen; (iv) concentrated samples obtained via a centrifugal filter device; and (v) samples stressed by 96h exposure to room temperature; or by using different doses (placebo, 25‐dose vials, 50‐dose‐vials and 125‐dose vials). Each freeze‐dried product was measured directly after freeze‐drying with FTIR spectroscopy. The collected spectra were analyzed using principal component analysis (PCA) and evaluated at three spectral regions, which might provide information on the coated proteins of freeze dried live, attenuated viruses: (i) 1700–1600 cm?1 (amide I band), 1600–1500 cm?1 (amide II band) and 1200–1350 cm?1 (amide III band). The latter spectral band does not overlap with water signals and is hence not influenced by residual moisture in the samples. It was proven that FTIR could distinguish between the freeze‐dried samples prepared using different virus medium volumes, containing different doses and using different pre‐freeze‐drying sample treatments in the amide III region. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:1107–1118, 2015  相似文献   

17.
This study explored the potential of using the gene therapy approach, based on adenovirus-mediated expression of pancreatic lipase in the hepatobiliary tract, to increase lipid digestion in the intestinal lumen and promote lipid absorption through the gastrointestinal tract. Recombinant adenovirus containing the human pancreatic lipase cDNA (AdPL) was shown to transduce and mediate pancreatic lipase biosynthesis in rat IEC-6 epithelial cells in vitro. Retrograde infusion of recombinant adenovirus (3 x 10(8) plaque-forming units) containing the bacterial LacZ gene (AdLacZ) into the bile duct of rats resulted in positive X-gal reaction products in the periportal liver cells 7 days after AdLacZ infusion. A high level of human pancreatic lipase was detected in bile after retrograde bile duct infusion of rats with AdPL but not in the bile of animals infused with AdLacZ. Triglyceride hydrolytic activity in the bile of AdPL-infused rats was equivalent to that present in pancreatic juice. In contrast, serum obtained from these animals did not contain any detectable pancreatic lipase activity. These results suggest that ectopic expression of pancreatic enzymes in the hepatobiliary tract may be an alternative therapeutic strategy for treating fat malabsorption due to pancreatic insufficiency.  相似文献   

18.
Patel  R.  Yago  M.D.  Mañas  M.  Victoria  E.M.  Shervington  A.  Singh  J. 《Molecular and cellular biochemistry》2004,261(1):83-89
This study investigated the effects of cholecystokinin-octapeptide (CCK-8) on pancreatic juice flow and its contents, and on cytosolic calcium (Ca2+) and magnesium (Mg2+) levels in streptozotocin (STZ)-induced diabetic rats compared to healthy age-matched controls. Animals were rendered diabetic by a single injection of STZ (60 mg kg–1, I.P.). Age-matched control rats obtained an equivalent volume of citrate buffer. Seven weeks later, animals were either anaesthetised (1 g kg–1 urethane; IP) for the measurement of pancreatic juice flow or humanely killed and the pancreas isolated for the measurements of cytosolic Ca2+ and Mg2+ levels. Non-fasting blood glucose levels in control and diabetic rats were 92.40 ± 2.42 mg dl–1 (n= 44) and >500 mg dl–1 (n= 27), respectively. Resting (basal) pancreatic juice flow in control and diabetic anaesthetised rats was 0.56 ± 0.05 ul min–1 (n= 10) and 1.28 ± 0.16 ul min–1 (n= 8). CCK-8 infusion resulted in a significant (p < 0.05) increase in pancreatic juice flow in control animals compared to a much larger increase in diabetic rats. In contrast, CCK-8 evoked significant (p < 0.05) increases in protein output and amylase secretion in control rats compared to much reduced responses in diabetic animals. Basal [Ca2+]i in control and diabetic fura-2-loaded acinar cells was 109.40 ± 15.41 nM (n= 15) and 130.62 ± 17.66 nM (n= 8), respectively. CCK-8 (10–8M) induced a peak response of 436.55 ± 36.54 nM (n= 15) and 409.31 ± 34.64 nM (n= 8) in control and diabetic cells, respectively. Basal [Mg2+]i in control and diabetic magfura-2-loaded acinar cells was 0.96 ± 0.06 nM (n= 18) and 0.86 ± 0.04 nM (n= 10). In the presence of CCK-8 (10–8) [Mg2+]i in control and diabetic cells was 0.80 ± 0.05 nM (n= 18) and 0.60 ± 0.02 nM (n= 10), respectively. The results indicate that diabetes-induced pancreatic insufficiency may be associated with derangements in cellular Ca2+ and Mg2+ homeostasis. (Mol Cell Biochem 261: 83–89, 2004)  相似文献   

19.
The aim of the present work was to study the endogenous contribution of the exocrine pancreatic and biliary secretions to the total endogenous nitrogen production in the pig. Three growing Large White pigs weighing 45 +/- 2.5 kg were fitted with permanent fistulae in the pancreatic duct, the bile duct and the duodenum. They were adapted to a semi-synthetic casein diet for 14 d before surgery. In a 7-d post-operative period and an 8-d experimental period, they were fed the same diet. Secretion rates were recorded, total nitrogen and TCA (trichloroacetic acid) insoluble nitrogen were determined in representative pancreatic juice and bile samples. Daily pancreatic juice and bile flow rates were very similar: 1,850 and 1,820 ml, respectively. The amount of endogenous total nitrogen secreted in the intestinal lumen was 3.6 g per day: 1.9 g N through pancreatic secretion and 1.7 g N through bile secretion. Pancreatic nitrogen increased after meal intake, whilst the kinetics of nitrogen production in the bile were not affected. Throughout the experiment, the mean percentage of TCA insoluble nitrogen was 78.1% in pancreatic juice and 72.3% in bile.  相似文献   

20.
《Carbohydrate research》1987,163(1):9-14
Laser-Raman spectra of Na+ kappa-carrageenan, Na+ neocarrabiose 4-sulphate, and neocarrabiose in the region 700–1500 cm−1 are reported for solutions in H2O and D2O. The C-1-H-1α vibration, coupled with COH related modes, is assigned to a band at 840 cm−1, close to the maximum of the symmetrical COS stretching (∼850 cm−1). The symmetrical SO stretch is proposed to occur near 1040 cm−1 and is probably coupled with COH vibrations which give rise to strong bands in the region 1000–1100 cm−1. The intense band in the region 730–740 cm−1 is ascribed to a complex ring vibration.  相似文献   

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