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991.
Changes in sugar composition (sucrose, glucose and fructose) of medium, callus, stem and leaves of in vitro proliferating explants of Actinidia deliciosa C.F. Liang, Hayward were analyzed together with explant growth at 0, 15, 30, 45 and 60 days of culturing. Autoclaving hydrolyzes a small part of the initial sucrose of the medium into glucose and fructose. In presence of Actinidia explants the initial sucrose decreased to 32% after 15 days of culturing, to 4% after 30 days and to 0.08% at the end of the culture period (60 days). Sucrose increase in the explants did not parallel with its decrease in the medium. Sucrose presence in the explants was evident only during the last month of culturing. After 15 days of culturing a large increase of glucose and fructose was found in the medium but it did not equal the hydrolyzed sucrose. The level of these two monosaccharides remained stable in the medium until the 30th day, then significantly decreased in the second month of culture; neither were completely exhausted at the end of the culture. In the whole explant the highest amount of glucose and fructose was reached after 30 days of culturing.The balance of the three sugars in the medium-explant system, as % distribution of carbon atoms, showed a utilization throughout the whole culture period.Qualitative analyses performed on medium, callus and leaves at 0, 15, and 30 days of culturing revealed the presence of glucose and fructose only and no significant amounts of other hexoses or pentoses. Starch accumulation in the leaves was also observed throughout the culturing.Paper No. 724  相似文献   
992.
The role of so called balanced translocations in human morphogenesis remains puzzling. An eleven month old hispanic female was referred for neurological evaluation. The major dysmorphic features include: epicanthal folds, flat nasal bridge, small mouth, micrognathia, low set ears and cleft-palate. The cytogenetic findings by multiple banding techniques revealed an apparent balanced translocation involving chromosomes 9p and 11p i.e. 46,XX,t(9;11)(p21.2;p14.2) which, according to the authors, has not been previously reported.  相似文献   
993.
4-hydroxynonenal (HNE) is one of the major breakdown products of cellular lipid peroxidation. Its effects on proliferation, ornithine decarboxylase (ODC) activity and DNA synthesis have been investigated in leukemic cell lines. The cells were incubated for 1 hour with different aldehyde concentrations, then washed and resuspended in medium with fresh foetal calf serum. HNE concentrations ranging from 10-5 to 10-6 M significantly inhibited ODC activity when induced by addition of fresh foetal calf serum both in K562 and HL-60 cells. 3H-Thymidine incorporation in K562 cells was also inhibited from 6 to 12 hours after the treatment. The same HNE concentrations did not inhibit ODC activity when added to cytosol, thus a direct action on the enzyme can be excluded. Moreover, HNE did not affect the half-life of ODC, so that a specific effect on ODC synthesis may be supposed. These data indicate a reduction of proliferative capacity of the cells and are consistent with the possibility that HNE, at concentrations close to those found in normal cells, plays a role in the control of cell proliferation.  相似文献   
994.
Synopsis The purpose of the present investigation was to determine at what stages of embryonic development the sodium pump (Na+,K+-activated ATP phosphohydrolase, EC 3.6.1.3) appears and whether the ontogeny of the sodium pump plays a role in the matrotrophic viviparity ofSebastes. Early larval stages (stages 1–14) had embryonic tissues nearly devoid of Na, K-ATPase activity. After epiboly, tissues from embryos taken from both species,S. schlegeli andS. taczanowskii, had significant levels of enzymatic activity coincident with the appearance of neuronal tissue in the head fold (stages 15–20). Maximal levels of specific activities of the enzyme were reached with the onset of the vascular circulation and the opening of the buccal cavity together with maturation of the midgut and hindgut regions of the intestinal tract (stages 26 and 28). Ouabain, a specific inhibitor of Na, K-ATPase, was used to measure survival of embryos placed in different seawater concentrations under in vitro conditions. The most sensitive stages to external ouabain were 26–30. These findings support the hypothesis that the intestinal tract is functional prior to gestation and could be transporting important nutritive material found in maternal ovarian fluid.  相似文献   
995.
Two-dimensional stress-strain relationship for canine pericardium   总被引:2,自引:0,他引:2  
Two-dimensional pseudoelastic mechanical properties of the canine pericardium were investigated in vitro. The pericardium was assumed to be orthotropic. The material symmetry axis was determined a priori and aligned with the stretching axis. Various biaxial stretching tests were then performed and a set of data covering a wide range of strains was constructed. This complete data set was fitted to a new exponential type constitutive model, and a set of true material constants was determined for each specimen. Using the constitutive model and the true material constants, the results from constant lateral force tests and constant lateral displacement tests were predicted and compared with experiment.  相似文献   
996.
997.
A capsid mutant of X174 is capable of forming replicative form and synthesizing single strands at the restrictive temperature in a dnaB mutant of Escherichia coli. Under similar conditions, the wild-type bacteriophage is incapable of either step in viral synthesis.  相似文献   
998.
999.
1000.
Context: The classification of flat non-neoplastic urothelial lesions has been evolved through the years in the attempt to better define a spectrum of morphologic entities with somewhat overlapping features. Differentiating these lesions is important because of differences in patient management and clinical outcome.

Materials and methods and objective: A systematic review of the literature has been carried out in order to (1) assess the most striking clinical features of each lesion and (2) identify those morphological traits and immunophenotypical markers which may aid in the differential diagnosis.

Results and conclusion: Our results point out the importance of a proper definition of flat non-neoplastic urothelial lesions in order to predict clinical behaviour and allow tailored patient management; therefore, we attempted to construct a novel and “easy to use” algorithm for a clear, standardized and evidence-based pathological diagnosis.  相似文献   

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