共查询到20条相似文献,搜索用时 15 毫秒
1.
Epperly MW Epperly LD Niu Y Wang H Zhang X Franicola D Greenberger JS 《Radiation research》2007,168(5):560-566
We determined whether manganese superoxide dismutase (MnSOD)-plasmid liposome (PL) transfection of C57BL/ 6NHsd mouse bone marrow protected cells irradiated at room temperature (24 degrees C) or in the cryopreserved state. MnSOD-overexpressing hematopoietic progenitor 2C6 cells were radioresistant compared to the parent 32D cl 3 cells when irradiated frozen or at 24 degrees C. Fresh whole marrow from mice injected intravenously with MnSOD-PL prior to explant as well as explanted marrow single cell suspensions transfected in vitro were irradiated at 24 degrees C or -80 degrees C. In vivo or in vitro transfection of marrow with MnSOD-PL produced significant radiation protection of irradiated marrow progenitor cells compared to controls at 24 degrees C or -80 degrees C. (in vivo transfection D(0) 2.19 +/- 0.21 at 24 degrees C, D(0) 2.10 +/- 0.07 at -80 degrees C compared to control D(0) 1.56 +/- 0.06 or 1.66 +/- 0.04, P = 0.047 and 0.017 respectively; in vitro transfection D(0) 2.35 +/- 0.11 at 24 degrees C, D(0) 3.42 +/- 0.13 at -80 degrees C compared to D(0) 1.81 +/- 0.01 or 2.53 +/- 0.05, P = 0.0087 and 0.0026, respectively). Thus the MnSOD transgene product protects frozen marrow cells as well as marrow cells irradiated at 24 degrees C. 相似文献
2.
The authors tested preserving properties of three concentrations of dimethylsulphoxide (15%, 10% and 7.5%) in preservation of rat bone marrow cells at -150 degrees C. Cells of rat bone marrow were frozen at 1 degree C/min to -20 degrees C, 5 degrees C/min to -80 degrees C and then placed directly at -150 degrees C and held at such temperature for 6 months. Vitality of cells was checked monthly for a period of 6 months by means of several vitality tests with dyes (eosin and trypane blue), autoradiography and erythrophagocytosis. It was found that cells capable of cleavage could be equally preserved at such low temperature with all the three DMSO concentrations while mature cells (granulocytes, reticular cells) revealed considerably higher erythrophagocytic activity when preserved at 15% DMSO and lower activity at 10% and 7.5% DMSO. 相似文献
3.
Ilouga PE Winkler D Kirchhoff C Schierholz B Wölcke J 《Journal of biomolecular screening》2007,12(1):21-32
The appropriate storage conditions for a compound file are a crucial factor for the success of drug discovery projects. In this study, 778 highly diverse compounds dissolved in 100% DMSO were stored under 3 industry-wide accepted storage conditions, and the compound integrity was monitored for a period of 6 months. The storage conditions selected were (1) under argon at +15 degrees C, (2) under argon at -20 degrees C, and (3) under ambient atmosphere at -20 degrees C. Each sample was assessed every 4 weeks by liquid chromatography coupled to mass spectrometry (LC/MS). Based on the resulting experimental data, a statistical projection of compound integrity over a period of 4 years for each of the 3 storage conditions was generated applying a linear mixed-effects model. A moderate loss of compound integrity of 12% was calculated for storage at -20 degrees C under argon, a loss of 21% for storage at -20 degrees C under ambient atmosphere, and a strong decrease of 58% for storage at +15 degrees C under argon over this period. The initial purity of the compounds does also influence the rate of compound degradation. Compounds with an initial purity of 50% to 75% degraded faster than compounds with an initial purity of more than 75%. The results of the study enable the prediction of the point in time, when the purity of a compound population falls below a predefined threshold that would trigger the resolubilization or retirement of the compound population represented by the analyzed samples. 相似文献
4.
A new bone banking technique to maintain osteoblast viability in frozen human iliac cancellous bone 总被引:2,自引:0,他引:2
The aim of this study was to develop a new cryopreservation technique to maintain the osteoblast viability in frozen iliac bone and to prove cell viability using cell culture techniques.Human iliac cancellous bones were frozen with and without 10% Me(2)SO at -80 degrees C. The tubes were kept in a -80 degrees C freezer for at least 2 days. After the storage period, the frozen bone was thawed by placing the tube in a 37 degrees C water bath. A serial enzymatic digestion technique using 0.2% collagenase was employed to isolate osteoblast-like cells from the bone. The cells that were released were inoculated into tissue culture flasks containing DMEM supplemented with 10% FCS. They were incubated at 37 degrees C in a humidified atmosphere of 95% air and 5% CO(2). Cells of the second passage were plated at a density of 5 x 10(3)cells/cm(2) in a 24-well plate and used for characterization. For characterization, WST-1 assay, determination of alkaline phosphatase, Type I collagen assay, osteocalcin assay, and von Kossa staining were used. The assays were performed at 3, 6, 9, and 12 days after plating the cells. Based on the results of this study, we conclude that the osteoblast-like cells in the frozen bone can survive, only when the bone is frozen with cryoprotectants to prevent injury during freezing and thawing. 相似文献
5.
Comparison of stem cell viability of bone marrow cryopreserved by two different methods 总被引:5,自引:1,他引:5
Two different cryogenic methods were used to study the preservation of murine bone marrow cells. Compared to the classical methods, in which separated mononuclear marrow cells in 10% dimethyl sulfoxide (DMSO) were cryopreserved in liquid nitrogen (-196 degrees C), a modified technique was carried out by cryopreservation of unfractionated marrow cells in a mixed protectant of 5% DMSO and 6% hydroxyethyl starch (HES) at -80 degrees C. Samples that were separately thawed after storage for 1, 4, 8, and 12 weeks were assayed for cell viability and recovery of CFU-GM and CFU-S. No macroscopic clumping of cells was noted either in fractionated or in unfractionated marrow cell cryopreservations. A mild damage, about 25% reduction of stem cells, was found at 1 week and did not deepen further. It seems that the greatest loss of stem cells occurred in the process of cryopreservation itself. Compared to prefreeze values, both a high number of cells that excluded trypan blue (87 +/- 3.4%) and a high recovery of CFU-GM (75 +/- 9.8%) and CFU-S (74 +/- 11.2) were observed in unfractionated marrow samples cryopreserved with the DMSO/HES mixture at -80 degrees C for 3 months and these results were very similar to those obtained from fractionated mononuclear marrow cells cryopreserved at -196 degrees C. The DMSO/HES protectant provides a simplified bone marrow cryopreservation technique that should be favorable to clinical application because of its high stem cell recovery and avoidance of cell-separation manipulation. 相似文献
6.
Mølbak L Sommer HM Johnsen K Boye M Johansen M Møller K Leser TD 《Current issues in intestinal microbiology》2006,7(1):29-34
Terminal-restriction fragment length polymorphism (T-RFLP) was used to evaluate how to store intestinal specimens for bacterial community analysis. Bacterial communities are increasingly often described by means of DNA-based methods and it is common practice to store intestinal or faecal specimens either at -20 degrees C or -80 degrees C. In this study, samples of intestines from five different pigs were stored at -80 degrees C and -20 degrees C, respectively and a thawing and freezing procedure was carried out three times for each intestinal per pig per temperature. The cumulative sum of the T-RFLP peak heights (T-RF intensities) decreased as the temperature decreased. The composition of the bacterial community changed when stored at -80 degrees C compared to the samples stored at -20 degrees C. Thus it is recommended from this study that samples of intestinal content are stored at -20 degrees C before use for bacterial community analysis, instead of the current practice at -80 degrees C. 相似文献
7.
Dog platelets were frozen with 6% dimethyl sulfoxide at 2-3 degrees C per minute in a -80 degrees C mechanical freezer. The frozen platelets were stored at -80 degrees C for as long as 39 months. After storage at -80 degrees C for less than 1 year, platelet in vitro freeze-thaw-wash recovery values were 70%, and in vivo survival values 1 to 2 hr after transfusion were 40% those of fresh platelets. After 2 years or longer storage, in vitro freeze-thaw-wash recovery values were 60%, and in vivo survival values 1 to 2 hr after transfusion were 20% those of fresh platelets. These results indicate that significant deterioration of the dog platelets occurred between the first and second year of storage at -80 degrees C. Platelets that were stored frozen at -80 degrees C for less than 1 year and washed before transfusion into lethally irradiated thrombocytopenic dogs were hemostatically effective. 相似文献
8.
Survival of Botrytis cinerea conidia was studied after storage without pretreatments at different temperatures (-80 degrees C, -20 degrees C, 4 degrees C and 21 degrees C). Germination tests performed during 3 years showed that viability at 21 degrees C was completely lost after 1 month. Conidia stored for 30 months at -80 degrees C, -20 degrees C and 4 degrees C were able to germinate, respectively, at 79%, 8% and 0.2%. Changes in adenylate level, energy charge and respiration (O(2) consumption) made on each set of conidia were correlated to the germination rate. The 30-month-old stored conidia showed differences in pathogenicity tests on apples. While the pathogenic aggressiveness of conidia stored at -80 degrees C was almost the same as for fresh conidia, it decreased with increasing temperature of storage. An ultrastructural study made on conidia stored for 30 months at -80 degrees C has shown the emergence of a new wall layer in a retraction zone of the cytoplasm by comparison to fresh conidia. However, the integrity of the cytoplasmic content was maintained. The effects of low temperature storage, maintenance of cell integrity and pathogenicity of conidia of B. cinerea are discussed. 相似文献
9.
A detailed circular dichroic (CD) study of the conformational flexibility of the melanin-concentrating hormone core [MCH(5-14)] is reported. Variable pH (2-10) and temperature (-80 degrees to +80 degrees C) in aqueous media reveal that CD contributions from tyrosine, disulphide bridge and the amide backbone can be discriminated. Only below -10 degrees C does a preferred -S-S-conformation (P chirality, dihedral angle phi = 90 +/- 10 degrees) dominate. The amide backbone CD contribution varies over all temperatures (-80 degrees to +80 degrees C) providing evidence for a type-II beta-turn at low temperatures, with the emergence of a type-I beta-turn at higher temperatures. Tyrosine exhibits a special behaviour at pH 7. These conclusions are in broad agreement with published NMR studies. Nevertheless, the MCH(5-14) core is seen to be conformationally flexible in aqueous solution at ambient temperatures. Conformation differences are observed in a non-aqueous environment. 相似文献
10.
This study was undertaken to investigate whether part of the ammonia formed during muscular exercise was excreted with the sweat. Male medical students volunteered for the experiment. They exercised 30 min on a bicycle ergometer at 80 and 40% of the predetermined maximal O2 uptake (VO2max). Exercise at 80% VO2max was performed twice, at room temperature (20 degrees C) and in a cold room (0 degrees C), whereas exercise at 40% was performed only at room temperature (20 degrees C). Blood was collected from the antecubital vein immediately before and after exercise. Sweat was collected from the hypogastric region by use of gauze pads. It was shown that the plasma ammonia level was elevated after exercise at 80% VO2max and remained stable after exercise at 40% VO2max. The volume of sweat produced during exercise at 80% VO2max at 20 degrees C was 428 +/- 138 ml and at 0 degrees C 245 +/- 86 ml and during exercise at 40% VO2max was 183 +/- 69 ml. The ammonia concentration in the sweat after exercise at 80% VO2max at 20 degrees C was 7,140 mumol/l and at 0 degrees C 11,816 mumol/l. After exercise at 40% VO2max, it was 2,076 mumol/l. The total ammonia lost through the sweat during exercise at 80% VO2max was similar at both temperatures, despite the difference in the sweat volume (at 20 degrees C, 3,360 +/- 2,080 mumol; at 0 degrees C, 3,310 +/- 1,250 mumol). During exercise at 40% VO2max, it was 350 +/- 230 mumol. These results show that part of ammonia formed during exercise is lost with sweat. The amount lost increases with increased work rate and the plasma ammonia concentration. 相似文献
11.
Numerous changes occur post-mortem in fish, affecting its chemical composition and nutritional quality. In the present paper we describe the effect of storage on ice or at -30 degrees C or -80 degrees C on 10 species of Mediterranean fish. Water and lipid soluble antioxidants, lipid pattern and products of oxidative attack on lipids, proteins and DNA were quantified for 7 consecutive days on homogenates of fish light muscle. The earliest events were oxidation of ubiquinol and vitamin C, which disappeared almost completely within 48 hours. Ubiquinol oxidation gave rise to an initial increase of ubiquinone, which peaked at the second day: thereafter ubiquinone itslef decreased, more rapidly and to a greater extent than vitamin E. The decrease in antioxidants was accompanied by significant oxidative damage to lipids, proteins and DNA. TBARS significantly increased beginning from the third day of storage in all species and were linked to a significant reduction in the n-3 PUFA of triglycerides (TG) and phospholipid fractions (PL). A remarkable elevation of protein carbonyls and 8OHdG occurred approximately 24 hours later than PUFA oxidation. For SOD, GPX and GSH significant depletions occurred for all species only at 6th or 7th day, but the final values were always higher than 50% compared to the initial ones. Deep-freezing of the same species at -30 degrees C and -80 degrees C for up to 12 months did not significantly affect the levels of enzymatic antioxidants, the redox couple GSH/GS-SG, n-3 and n-6 PUFA of TG and PL fractions of the light muscle. The only antioxidants, which at -30 degrees C and -80 degrees C appeared to be degraded after 6 and 12 months were ubiquinol and vitamin C. As expected their degradation was higher at -30 degrees C than at -80 degrees C. In fact the average decrease for ubiquinol at -80 degrees C was 42% at 6 and 12 months respectively, whereas at -30 degrees C the decrease was 61% and 87% For vitamin C the average decrease at -80 degrees C was 36% and 67% at 6 and 12 months respectively, and at -30 degrees C it was 61% and 82%. Vitamin E was considerably more stable than ubiquinol and vitamin C. The relative stability of the antioxidants, with the exceptions of ubiquionols, vitamin C and, to a certain extent, vitamin E, was accompanied by a very limited increase in oxidation products. In addition no significant hydrolysis of TG and PL fractions were observed throughout the storage time. The dynamics of lipid, protein and DNA oxidation is discussed in the light of depletion of the various antioxidant systems. 相似文献
12.
Free-living bacteria must respond to a wide range of temperature changes, and have developed specific mechanisms to survive in extreme environments. In this work we describe a remarkable resistance of mesophilic bacterium Caulobacter crescentus to several cycles of freezing at -80 degrees C, which was able to grow at low temperatures. Exponentially growing cells and late stationary-phase cells presented higher freezing resistance at both -20 and -80 degrees C than early stationary-phase cells. Cryotolerance was observed when log-phase cultures grown at 30 degrees C were preincubated at 5, 15 or 20 degrees C before freezing at -20 degrees C. A transposon library was screened to identify mutants sensitive to freezing at -80 degrees C and three strains presenting <10% survival were isolated. Identification of genes disrupted in each mutant showed that they encoded an AddA family DNA helicase, a DEAD/DEAH box RNA helicase and a putative RND (resistance, nodulation, cell division) efflux system component. These strains showed longer generation times than wild-type cells when growing at 15 degrees C, with the RNA helicase mutant presenting a severe growth defect. These analyses suggest that the singular intrinsic resistance to freezing of C. crescentus is in fact a consequence of several independent traits, especially the maintenance of a proper degree of supercoiling of nucleic acids. 相似文献
13.
Binding of 125I-labeled granulocyte colony-stimulating factor to normal murine hemopoietic cells 总被引:13,自引:0,他引:13
The binding of granulocyte colony-stimulating factor (G-CSF) to murine bone marrow cells was investigated using a radioiodinated derivative of high specific radioactivity which retained full biological activity. The binding was time- and temperature-dependent, saturable and highly specific. The apparent dissociation constant for the reaction was 60-80 pM at 37 degrees C and 90-110 pM at 4 degrees C, similar to that found for the binding of G-CSF to murine leukemic cells (WEHI-3B D+) and significantly higher than the concentration of G-CSF required to stimulate colony formation in vitro. Autoradiographic analysis confirmed the specificity of binding since granulocytic cells were labeled but lymphocytes, erythroid cells and eosinophils were not. Blast cells and monocytic cells were partially labeled, the latter at low levels. In the neutrophilic granulocyte series, grain counts increased with cell maturity, polymorphs being the most heavily labeled but all cells showed considerable heterogeneity in the degree of labeling. Combination of Scatchard analysis of binding with autoradiographic data indicated that mature granulocytes from murine bone marrow exhibited 50-500 G-CSF receptors per cell. 相似文献
14.
Importance of storage conditions for the stability of zinc- and cadmium-induced metallothionein 总被引:2,自引:0,他引:2
We examined the storage stability of metallothionein (MT), a cysteine-rich protein that has diagnostic potential as a cancer marker and in the assessment of Zn status and heavy-metal toxicity. MT was rapidly degraded in samples of rat whole liver at -20 degrees C or -70 degrees C. MT in supernatants from heat-treated rat liver homogenates stored as 1:5 dilutions of liver from Zn- or Cd-induced rats were stable (recovery >98%) for 100 d at temperatures of -70 degrees C and -196 degrees C but not at -20 degrees C, regardless of the presence of dithiothreitol (DTT) or argon. The variability of MT measurement by the 109Cd-hemoglobin affinity assay was however greatest in samples from Zn-induced rats stored without DTT. The integrity of the MT protein in supernatants of heat-treated homogenates stored for 100 d was demonstrated by Sephadex G-75 chromatography. When heat-treated supernatants were stored as dilute solutions (1:125 of liver), MT was unstable regardless of treatment or storage temperature. Our findings show that liver MT is stable for at least 4 mo as a supernatant of a heat-treated homogenate (1:5 dilution of liver) when stored at or below -70 degrees C and in the presence of DTT. 相似文献
15.
Enzymes of energy metabolism were tested for stability depending on different storage conditions (-20, -80 degrees C). To avoid problems due to the different fiber type composition of human muscle, we selected two muscles from rabbit. The m. psoas consists almost exclusively of type 2B fibers, and the m. soleus consists almost exclusively of type 1 fibers. Enzyme activities were measured from small aliquots of these muscles at various time points up to 1 year after sacrificing the animal. Enzymes from anaerobic metabolism were stable for more than 1 year, independent of whether the muscle was stored at -20 or -80 degrees C. Oxidative enzymes, such as succinate dehydrogenase, citrate synthetase, or cytochrome c oxidase (COX) decrease in activity at -20 degrees C and, to a lesser degree, at -80 degrees C. In addition, mitochondria were isolated from freshly taken muscle and stored at -80 degrees C. Oxidative enzymes were surprisingly stable for more than 1 year, with the exception of COX which decreased by 60% of its original activity in mitochondria from m. soleus. 相似文献
16.
A novel thermostable xylanase from Thermomonospora sp.: influence of additives on thermostability 总被引:1,自引:0,他引:1
An alkalothermophilic Thermomonospora sp. producing high levels of xylanase was isolated from self-heating compost. The culture produced 125 IU/ml of xylanase when grown in shake flasks at pH 9 and 50 degrees C for 96 h. The culture filtrate also contained cellulase (23 IU/ml), mannanase (1 IU/ml) and beta-xylosidase (0.1 IU/ml) activities. The xylanase was active at a broad range of pH (5-9) and temperature (40-90 degrees C). The optimum pH and temperature were 7 and 70 degrees C, respectively. The enzyme was stable in the pH range 5-8 and was thermostable with half-lives of 8 and 4 h at 60 degrees C and 70 degrees C, respectively, but only 9 min at 80 degrees C. The effects of a variety of compounds to enhance the stability of xylanase at 80 degrees C was studied. Addition of sorbitol, mannitol and glycerol increased the thermostability of xylanase in proportion to the number of hydroxyl groups per polyol molecule. Glycine also offered protection against thermoinactivation. Xylan, trehalose, gelatin and trehalose-gelatin mixture had marginal effect on the thermostability of xylanase at 80 degrees C. 相似文献
17.
The aim of this study was to compare the viability of human osteoblasts cryopreserved with Me2SO to that of fresh human iliac cancellous bone using cell culture techniques. Osteoblasts were obtained by spontaneous outgrowth of human iliac cancellous bone specimens in experiment I. In experiment II, human iliac cancellous bone was frozen with 10% Me2SO at -80 degrees C for 2 weeks and osteoblasts grew spontaneously after thawing at 37 degrees C by removing Me2SO with sucrose. The cells were grown in culture flasks containing DMEM as a culture medium, supplemented with 10% fetal calf serum. They were kept at 37 degrees C in a humidified atmosphere of 95% air and 5% CO2. Cells from the second passage were plated at a density of 5 times 10(3) cells/cm2 in 24-well plates. For detection of viability and differentiation, WST-1 assay, determination of alkaline phosphatase activity, concentration of procollagen I peptide, concentration of osteocalcin, and indirect immunofluorescence for osteopontin, collagen type I, integrin beta1, and fibronectin were applied. Experiments were conducted at four stages of confluence (days 4, 7, 14, and 21 after plating the cells). Based on the results of this study, we conclude that osteoblast-like cells survived cryopreservation and synthesized a range of markers that were consistent with this cell type. 相似文献
18.
Small-angle neutron scattering (SANS) measurements were performed on a solution of single-strand DNA, 5'-ATGCTGATGC-3', in sodium phosphate buffer solution at 10 degrees C temperature increments from 25 degrees C to 80 degrees C. Cylindrical, helical, and random coil shape models were fitted to the SANS measurements at each temperature. All the shapes exhibited an expansion in the diameter direction causing a slightly shortened pitch from 25 degrees C to 43 degrees C, an expansion in the pitch direction with a slight decrease in the diameter from 43 degrees C to 53 degrees C, and finally a dramatic increase in the pitch and diameter from 53 degrees C to 80 degrees C. Differential scanning calorimeter scans of the sequence in solution exhibited a reversible two-state transition profile with a transition temperature of 47.5 +/- 0.5 degrees C, the midpoint of the conformational changes observed in the SANS measurements, and a calorimetric transition enthalpy of 60 +/- 3 kJ mol(-1) that indicates a broad transition as is observed in the SANS measurements. A transition temperature of 47 +/- 1 degrees C was also obtained from ultraviolet optical density measurements of strand melting scans of the single-strand DNA. This transition corresponds to unstacking of the bases of the sequence and is responsible for the thermodynamic discrepancy between its binding stability to its complementary sequence determined directly at ambient temperatures and determined from extrapolated values of the melting of the duplex at high temperature. 相似文献
19.
We recently identified phosphatidylethanol (Pet) in tissues from ethanol-treated rats. Since phosphatidyl esters are formed artefactually during freezing in plants we wanted to examine if PE was elevated during freezing in animal tissues. Rats were treated with 3 g/kg of ethanol, killed after 3 h and PE was isolated from kidneys at once or after storage at 0, -5, -10, -15, -20 and -80 degrees C for 7 days. Kidneys analyzed at once or after storage at -80 degrees C had Pet equivalent to 0.02 mumol Pet/g. Storage at -10 degrees C and -15 degrees C resulted in increases of Pet to 1.5 mumol Pet/g and 1.2 mumol Pet/g, respectively. Thus, Pet is artefactually elevated during storage of tissues from ethanol-treated rats at lower freezing temperatures, reflecting considerable changes in composition of acidic phospholipids. 相似文献
20.
As a series of studies on postmortem changes in the fine structure of porcine muscle, activity of two mitochondrial marker enzymes, succinate dehydrogenase (SDH) and magnesium dependent adenosine triphosphatase (Mg-ATPase), was measured and localized in cardiac, red and white muscles stored at 4 degrees C, -18 degrees C or -80 degrees C. The postmortem loss of SDH activity was most remarkable in cardiac muscle. The variation of SDH activity was proportional to the amount of absolute activity. The postmortem change of Mg-ATPase was more variable than SFH, though the activity was well preserved up to 15 weeks in all three types of porcine muscle stored at -80 degrees C. The loss of Mg-ATPase was most remarkable in red muscle stored at -18 degrees C or -80 degrees C. Cytochemical localization of SDH was between the outer and the inner mitochondrial membranes while that of Mg-ATPase was on the inner surface or matrix side of the inner membrane. Those localization was not altered by the difference in temperature and the duration of storage. 相似文献