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1.
There is now strong evidence that the chorioretinal degeneration associated with ornithine-delta-aminotransferase (OAT) deficiency is a consequence of hyperornithinemia. Therefore development of a metabolic system for clearing ornithine from the circulation is being pursued as a potential treatment. The skin is considered an attractive location for such a metabolic system because autologous cells can be safely and easily utilized. This study was undertaken to determine the ornithine metabolizing capacity of epidermal keratinocytes expressing normal and superphysiologic amounts of OAT. The data show that overexpression of OAT in keratinocytes cultured from a gyrate atrophy patient restores ornithine metabolism and results in a rate of ornithine disappearance from the medium that is significantly higher than the rate of disappearance from the medium bathing normal keratinocytes. In addition, OAT activity determined in soluble protein prepared from sonicates suggests that the capacity to maintain plasma ornithine within the normal range is contained within an accomplishable graft of keratinocytes overexpressing OAT. However, the actual rate of ornithine disappearance from the media was significantly less than predicted from enzyme activity assays. Following ornithine metabolite production by intact cells suggests that ornithine metabolism is limited primarily by clearance of downstream metabolites, as opposed to substrate delivery.  相似文献   

2.
Women in whom a hereditary increased risk of breast cancer is established are often moved by anxiety to ask a surgeon for intensive periodical checking of the breasts or prophylactic resection breast tissue. This article contains a consensus on the relevant policy reached by surgeons from the two cancer centres and eight university hospitals in the Netherlands. Intensive follow-up is indicated only when the risk of breast cancer is twice as high as in women from the population in general. The age from which check-up examinations are carried out is from 25 years or from 5 years before the age at which the youngest relative developed breast cancer. For female gene carries from families with hereditary breast cancer, whether or not identified, the risk of death from breast cancer in spite of intensive follow-up is 7-20%. Preventive bilateral mastectomy is recommended only in case of a demonstrated gene mutation or a life-long risk of breast cancer in excess of 50%. Even after preventive surgical treatment, women should report annually for examination, because frequently a little mammary tissue remains behind.  相似文献   

3.
Experimental conditions are described for the in vitro study of explanted eyes from embryos of Xenopus laevis and of retinas from older larvae. When eyes are explanted from embryos of stages 25-34, a rapid outgrowth of fibroblast-like and pigment cells is observed, upon which a neuritic outgrowth is eventually superimposed. Outgrowth from the retina of later stage tadpoles (50-54) is not seen until about a week following explantation and resembles the mixed cell outgrowth observed in whole eye explants from early stage embryos. If, however, the optic nerve of an older tadpole is cut 7 days prior to explantation, a purely neuritic outgrowth is seen from the previously denervated retina within 1-3 days.  相似文献   

4.
In a direct ion selective electrode method for determining nitrite in smoked fish, the nitrite extracted from the sample is converted to nitrous acid with a measured addition of an acid buffer. The released nitrous acid is measured by a nitrogen oxide electrode. A known addition procedure is used to accurately measure the amount of nitrite in solution and the nitrite concentration is determined directly from Gran's plot paper. Recoveries of nitrite from spiked smoked chub samples ranged from 94.0 to 100.0% with an average of 96.7 and a relative standard deviation of +/-1.9% at the 100 ppm level. Results from the ion selective method were comparable with those from the official first action AOAC method 24.037-24.038.  相似文献   

5.
A model for calculating the variation in output of symmetric, asymmetric and irregularly shaped wedged radiotherapy fields is presented. The variation in output from the treatment head when a wedge is used is calculated by dividing the output into a primary component and one due to scattered radiation. The scatter component is then further subdivided into contributions from elements which have a 1 cm x 1 cm cross-sectional area at the isocentre. The scatter from each element is determined as the contribution from the head scatter component modified by the presence of the wedge and a contribution due to additional scattered radiation from the wedge. The relative intensity of the scattered radiation from the wedge is modelled using a simple first scatter approximation. In this approximation the magnitude of the scatter is given by a t exp(-mu t) function where t is the thickness of the wedge for the selected element. The magnitude of the primary component and the relative intensity of scatter from each element are then obtained by an iterative fit to measured data. The technique has been applied to two different internally mounted wedge designs, for a standard treatment head, two asymmetric treatment heads and two similar multileaf collimators, over a range of energies between 4 and 20 MV. Calculations agree with measured values over a range of field sizes and shapes to within 1.5%.  相似文献   

6.
IBC Advanced Technologies’ Molecular Recognition Technology(MRT) SuperLig products selectively and rapidly bind with target species enabling their selective removal from solutions.The MRT process can produce a high purity separation product of maximum added value at a competitive cost.SuperLig products have high selectivity for many target species which can include metal ions,anions,and neutral molecules.In operation,the SuperLig product is first placed in a packed column.A solution containing a mixture of the target species and other chemical species is then passed through the column.The target species is removed selectively by the SuperLig product,the column is washed to remove residual feed solution,and the target species is recovered by a minimal quantity of eluent.The result is a pure and concentrated species that can be kept for its value or disposed of safely.The process is environmentally and ecologically friendly with no organic solvents being used.This paper provides a review of some examples of applications of MRT to separations of interest to the Chinese metallurgical industry.Included are several applications of MRT,including Pd separations from Pt metal refinery streams and low-grade spent catalyst wastes,Rh recovery from spent auto catalyst and other feeds,Re removal from selected impurity ions,Cd removal from Co electrolyte,Bi removal from Cu electrolyte,In and Ge separations from difficult matrices,and removal of bivalent first transition series and other metal ions from acid mine drainage(Berkeley Pit,Montana).Finally,the potential application of MRT to separations involving the recovery of rare earth metals and Li from low-level waste solutions and end-of-life products is discussed.  相似文献   

7.
An open reservoir for the collection and evacuation of anaesthetic gases permits leakage to room air. The use of a closed reservior for the removal of overspill gas from anaesthetic circuits is described. Calibrated gas evacuation is carried out through an ejector flowmeter from the anesthetic circuit or from a closed reservoir, where the gas is collected via a relief valve. In order to eliminate the risk of high or low pressure in the reservoir employed, a relief valve and a dumping valve is included in the system.  相似文献   

8.
Measurement of cerebral blood flow (CBF) using a 133Xe inhalation technique requires monitoring the clearance rate of the radioisotope from the head using externally situated detectors and also from arterial blood using a detector to monitor the expired air activity. The end-tidal concentration function is assumed to be proportional to the arterial concentration function and this has to be deconvoluted from the clearance functions obtained from the head to enable CBF to be calculated. A digital computer is generally considered to be essential for this. In this paper a procedure using three-dimensional nomograms is derived and tested. It is shown that results obtained using the nomograms do not differ significantly from results obtained using a full deconvolution procedure, and so it is not essential to use a computer to calculate CBF by the inhalation technique.  相似文献   

9.
High-pressure chromatography on Spheron 300 BTD and Spheron 1000 was used to separate tobacco mosaic virus from other components of an extract from infected tobacco leaves, including F1, a protein having a molecular weight of 0.58 X 10(6). Comparative experiments have shown that the virus is not adsorbed by the carrier and is eluted in the free volume of the column; the virus is free from contamination by vegetable-juice components and is regained quantitatively. The virus can be separated partially, but distinctly, from the F1 protein by using a column of microgranular Spheron 300. Polyhydric phenols in the vegetable extract are adsorbed on Spheron and eluted from the column after a delay.  相似文献   

10.
The signal flow diagram is a graphic method used to represent complex data that is found in the field of biology and hence the field of medicine. The signal flow diagram is analyzed against a table of data and a flow chart of data and evaluated on the clarity and simplicity of imparting this information. The data modeled is from previous clinical studies and nontraditional medicine from Africa, China, and South America. This report is a development from previous presentations of the signal flow diagram.1-4  相似文献   

11.
Embutramide is a general anesthetic having a strong narcotic effect on the central nervous system where it paralyzes the brain center that controls respiration. It is a constituent of T61, a veterinary euthanasia drug. This paper describes a gas chromatographic procedure using nitrogen-phosphorus detection for the determination of embutramide in biological matrices. The drug and the internal standard (ambucetamide) are extracted with dichloromethane under alkaline conditions. The method is linear from 100 to 3000 ng/ml. The within-day and day-to-day coefficients of variation range from 5.1 to 5.7% and from 9.1 to 10.0%, respectively. The recovery is above 80% while the minimum detectable level under the conditions described is 40 ng/ml analyzing a 1-ml or a 1-g aliquot of a sample (blood or tissue). The method is also applied to different samples from dogs euthanized with T61.  相似文献   

12.
Two beta-lactamase genes from Aeromonas sobria, strain 163a, have been cloned and sequenced, one encoding a typical class C cephalosporinase, designated CepS, the other a class D penicillinase, designated AmpS. CepS is predicted to be a mature protein of 38 kDa with a pI value of 7.0. The amino acid sequence of CepS is most similar to that of AmpC from Pseudomonas aeruginosa (54.7%). AmpS is predicted to be a mature protein of 27 kDa with a pI value of 7.9 that mostly closely resembles BLAD from Klebsiella pneumoniae (42.2%), and OXA-1 from Escherichia coli (36.6%), beta-lactamases that are encoded by genes carried on multiresistant transposons. AmpS differs significantly from the other class D beta-lactamases in that it hydrolyses cloxacillin poorly and is inducible. Both genes exhibit a high overall GC content and possess a high NNC and NNG codon preference, similar to that of genes from Pseudomonas spp.  相似文献   

13.
The mitochondrial processing peptidase (MPP) is a heterodimeric enzyme that forms part of the cytochrome c reductase complex from higher plants. Mitochondria from mammals and yeast contain two homologous enzymes: (i) an active MPP within the mitochondrial matrix and (ii) an inactive MPP within the cytochrome c reductase complex. To elucidate the evolution of MPP, the cytochrome c reductase complexes from lower plants were isolated and tested for processing activity. Mitochondria were prepared from the staghorn fern Platycerium bifurcatum, from the horsetail Equisetum arvense, and from the colorless algae Polytomella, and cytochrome c reductase complexes were purified by a micro-isolation procedure based on Blue-native polyacrylamide gel electrophoresis and electroelution. This is the first report on the subunit composition of a respiratory enzyme complex from a fern or a horsetail. The cytochrome c reductase complexes from P. bifurcatum and E. arvense are shown to efficiently process mitochondrial precursor proteins, whereas the enzyme complex from Polytomella lacks proteolytic activity. An evolutionary model is suggested that assumes a correlation between the presence of an active MPP within the cytochrome c reductase complex and the occurrence of chloroplasts.  相似文献   

14.
The recovery of radium and EDTA from a leach solution used to extract radium from uranium mill solids is described. Ion-exchange is shown to effectively remove radium from the leach solutions. A relationship for the distribution of radium and other ions between the ion-exchange resin and the aqueous phase is developed. The EDTA is recovered in a two-stage process: lime treatment and acid precipitation. The total recovery of EDTA is about 95%. An outline of a process to recover radium and recycle EDTA is given.  相似文献   

15.
Animal agriculture is increasingly regarded as a source of pollutants such as gases, odours and particulates which may be both aggravating and ecologically harmful. An overview of the origin, number and quantity of pollutants emitted from animal housing and from manure stores is presented and possible means of preventing or reducing them are discussed. Of the 136 trace gases in the air of animal houses ammonia (NH3), methane (CH4) and nitrous oxide (N2O) present the greatest risk to the environment. The gases and particulates are emitted principally from freshly deposited and stored excreta, from animal feed, from litter and from the animals themselves. Total NH3 emissions from animal production in Germany are estimated as approximately 750,000 t/a. It is calculated that the average of which is higher than the average "critical loads" for most natural habitats. However, there is still a shortage of satisfactory information on the extent of emissions, in particular on those from naturally ventilated animal houses. NH3 has a direct effect on the trees in the vicinity of animal houses and is also transported long distances through the air contributing to eutrophication and acidification of water and soil. This frequently results in changes in plant ecology, hence reducing plant diversity. CH4 and N2O contribute to the "greenhouse effect". Emissions of CH4 from animal husbandry in Germany are estimated at about 1.5 Mt/a. This corresponds to 0.2% of the assumed global emission from all sources. There is still little knowledge about the quantities of N2O released from agricultural animals. The concentration of airborne microorganisms in livestock housing is between some 100 and several 1000 per liter of air.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

16.
The Z-score of a protein is defined as the energy separation between the native fold and the average of an ensemble of misfolds in the units of the standard deviation of the ensemble. The Z-score is often used as a way of testing the knowledge-based potentials for their ability to recognize the native fold from other alternatives. However, it is not known what range of values the Z-scores should have if one had a correct potential. Here, we offer an estimate of Z-scores extracted from calorimetric measurements of proteins. The energies obtained from these experimental data are compared with those from computer simulations of a lattice model protein. It is suggested that the Z-scores calculated from different knowledge-based potentials are generally too small in comparison with the experimental values.  相似文献   

17.
IBC Advanced Technologies' Molecular Recognition Technology (MRT) SuperLig(r) products selectively and rapidly bind with target species enabling their selective removal from solutions. The MRT process can produce a high purity separation product of maximum added value at a competitive cost. SuperLig(r) products have high selectivity for many target species which can include metal ions, anions, and neutral molecules. In operation, the SuperLig(r) product is first placed in a packed column. A solution containing a mixture of the target species and other chemical species is then passed through the column. The target species is removed selectively by the SuperLig(r) product, the column is washed to remove residual feed solution, and the target species is recovered by a minimal quantity of eluent. The result is a pure and concentrated species that can be kept for its value or disposed of safely. The process is environmentally and ecologically friendly with no organic solvents being used. This paper provides a review of some examples of applications of MRT to separations of interest to the Chinese metallurgical industry. Included are several applications of MRT, including Pd separations from Pt metal refinery streams and low-grade spent catalyst wastes, Rh recovery from spent auto catalyst and other feeds, Re removal from selected impurity ions, Cd removal from Co electrolyte, Bi removal from Cu electrolyte, In and Ge separations from difficult matrices, and removal of bivalent first transition series and other metal ions from acid mine drainage (Berkeley Pit, Montana). Finally, the potential application of MRT to separations involving the recovery of rare earth metals and Li from low-level waste solutions and end-of-life products is discussed.  相似文献   

18.
Curvature and Bending Moments from Inclinometer Data   总被引:1,自引:0,他引:1  
Bending moments in excavation support walls and deep foundations are frequently estimated using curvature derived from inclinometer surveys. The basic idea involves fitting a curve or a series of curves to the inclinometer data. The curvature is then estimated as the second difference of the displacement profile. Although many methods are available to estimate curvature, there is a lack of a consistent standard in deducing curvature from inclinometer readings. Twelve methods for estimating curvature that lend themselves well to spreadsheet or programmable calculations are reviewed. They are then applied to 60 sets of inclinometer readings obtained from a variety of walls and drilled shafts. Included are six laterally load tested drilled shafts which were monitored using both inclinometers and strain gauges. A direct comparison of curvatures from inclinometers with those from strain gauges was performed. The comparisons show that a piecewise cubic polynomial curve fitting a moving window of five successive inclinometer data points provide curvature values that are in good agreement with those from strain gauges, and is proposed as a reasonable method for estimating bending moments from inclinometer data.  相似文献   

19.
Alkaline-fermented foods constitute a group of less-known food products that are widely consumed in Southeast Asia and African countries. They can be made from different raw ingredients. For instance, Japanese natto, Thai thua-nao, and kinema are made from cooked soybeans, dawadawa from African locust beans, ogiri from melon seeds, ugba from African oil beans, kawal from fresh legale leaves, owoh from cotton seeds, and pidan from fresh poultry eggs. In alkaline-fermented foods, the protein of the raw materials is broken down into amino acids and peptides; ammonia is released during the fermentation, raising the pH of the final products and giving the food a strong ammoniacal smell. Most alkaline fermentations are achieved spontaneously by mixed bacteria cultures, principally dominated by Bacillus subtilis. In other cases, pure cultures can be used. For example, Japanese natto is inoculated with a pure culture of B. subtilis var natto. Pidan is a special example of alkaline fermentation. Instead of using microorganisms, pidan is made using an alkali-treated fermentation. Sodium hydroxide (NaOH) is produced from the reaction of sodium carbonate (Na2CO3), water (H2O), and calcium oxide (CaO) of pickle or coating mud. NaOH penetrates into the eggs, causing the physicochemical changes, color changes, and gelation. The appearance of pidan differs from fresh eggs in that the white becomes a semitransparent tea-brown color, and the yolk is solid or semisolid with a dark-green color. The nutritional value of pidan is slightly decreased compared with fresh eggs, but pidan has an extremely long shelf life and a pleasant, fragrant taste that is preferred by most people in Southeast Asian countries. In a small-scale laboratory study conducted by the authors, B. subtilis was not found in pidan. Four Staphylococcus spp. (S. cohnii, S. epidermidis, S. haemolyticus, and S. warneri) and two strains of Bacillus spp. (B. cereus and B. macerans) were isolated from pidan. Staphylococcus spp. did not contribute to the fermentation and were considered contaminants.  相似文献   

20.
The relative contribution to household dust of lead particles from a mining waste superfund site and lead-based paint is investigated. Automated individual particle analysis (IPA) based on scanning electron microscopy (SEM) and X-ray energy spectroscopy (EDX) is used to develop a classification algorithm for determining lead particle source contribution in household dust vacuum bags. On a volume basis the proportion derived from the mining waste is found to be 26%, the proportion derived from a paint source is 16%, and the proportion from soil is 37%. In 15% of the lead particles identified a specific originating source could not be determined. Using a weighting method accounting for the lead concentration per particle rather than volume the contributions were similar for mining waste and paint, 21% and 23%, respectively, but the soil contribution was reduced to 8%, and the source for 29% of the lead could not be identified. These results suggested that the contribution of waste piles to the lead present in household dust is at least as important a source as paint. There is evidence to suggest that a large percentage of lead in the soil also originated from the waste piles and the overall contribution, therefore, of the waste piles may be greater than the contribution from paint.  相似文献   

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