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1.
Subacute dose of 0,0-diisopropyl phosphorofluoridate (DFP), a potent organophosphorus ester capable of producing delayed neurotoxicity (OPIDN), did not produce any significant change in the levels of lysosomal and mitochondrial marker enzymes of brain, liver and serum at any time after treatment in hens protected with atropine. The results suggest the absence of any involvement of mitochondrial and lysosomal enzymes at any stage in the development of OPIDN in susceptible species by treating with DFP.  相似文献   

2.
E. D. Hodby  J. Hirsh  C. Adeniyi-Jones 《CMAJ》1972,106(5):562-564
Although physical incompatibility between heparin and a number of drugs has been reported we did not discover any evidence of such incompatibility when heparin was mixed with 11 commonly used drugs in therapeutic concentrations.Furthermore, there was no detectable change in the anticoagulant activity in the presence of any of these drugs, nor was there any change in the biological activity of the antibiotics tested.  相似文献   

3.
The cerebral cortex of normal oxygenated and of asphyxiated mice has been studied by freeze-fracturing technique with a twofold purpose. First, to investigate changes, if any, in the molecular organization of the plasma membrane of any specific cell type(s) that could be correlated with permeability changes thought to take place as a consequence of asphyxiation. Secondly, to attempt characterization of plasma membranes on the basis of the organization of their fractured faces. The decrease in the extracellular material in asphyxiated cerebral cortex seen in electron micrographs of thin sections could not be correlated with change(s), if any, in the molecular organization of the plasma membrane of any particular cell type. Plasma membranes of various types could be characterized on the basis of the arrangement of particles on the fractured faces. Some of these types correspond to identifiable cell processes, while others have not yet been identified with certainty. Fusion of synaptic vesicles with the presynaptic membrane is mediated through clustering of 100-150 A membrane-associated particles.  相似文献   

4.
Automated statistical analysis of microbial enumeration by dilution series   总被引:9,自引:1,他引:8  
Equations are formulated for the standard error and confidence interval for the MPN estimate of microbial density from a general dilution series. A statistical test of homogeneity is presented. This tests whether a handling error in the dilution series may have occurred which would invalidate the density estimate. The analysis may be automated using a Basic computer program which contains a fast algorithm for the solution of the general MPN equation. This allows the calculation of the MPN, standard error, 95% confidence interval and test statistic for any dilution series, with any degree of replication at each dilution level, with variable sample volumes at each dilution level, with variable dilution ratio between levels, and with any number of levels.  相似文献   

5.
The cerebral cortex of normal oxygenated and of asphyxiated mice has been studied by freeze-fracturing technique with a twofold purpose. First, to investigate changes, if any, in the molecular organization of the plasma membrane of any specific cell type(s) that could be correlated with permeability changes thought to take place as a consequence of asphyxiation. Secondly, to attempt characterization of plasma membranes on the basis of the organization of their fractured faces. The decrease in the extracellular material in asphyxiated cerebral cortex seen in electron micrographs of thin sections could not be correlated with change(s), if any, in the molecular organization of the plasma membrane of any particular cell type. Plasma membranes of various types could be characterized on the basis of the arrangement of particles on the fractured faces. Some of these types correspond to identifiable cell processes, while others have not yet been identified with certainty. Fusion of synaptic vesicles with the presynaptic membrane is mediated through clustering of 100–150 Å membrane-associated particles.  相似文献   

6.
In order to carry out non-conservative tests in the general two-sample problem with ties, we want to know all possible sample-values of the used test statistics and their occurrence probabilities as well. But this knowledge can be acquired only after very protracted attempts. In the present paper we depict a simple technique for obtaining that without any exertion in the case of the Wald-Wolfowitz test statistic. With that, we then are able to lead the Wald-Wolfowitz test easily and effortlessly in any manner conservative or non-conservative and in the existence of any number and any length of ties.  相似文献   

7.
The adoptive transfer of antigen-specific cytotoxic T lymphocytes (CTLs) is a promising therapeutic approach for a number of diseases. To overcome the difficulty in generating specific CTLs, we established stable artificial antigen-presenting cells (AAPCs) that can be used to stimulate T cells of any patient of a given human leukocyte antigen (HLA) type. Mouse fibroblasts were retrovirally transduced with a single HLA-peptide complex along with the human accessory molecules B7.1, ICAM-1, and LFA-3. These AAPCs consistently elicit strong stimulation and expansion of HLA-restricted CTLs. Owing to the high efficiency of retrovirus-mediated gene transfer, stable AAPCs can be readily engineered for any HLA molecule and any specific peptide.  相似文献   

8.
Interactions of DNA binding ligands with PNA-DNA hybrids.   总被引:1,自引:1,他引:0       下载免费PDF全文
The interactions of two representative mixed-sequence (one with an AT-stretch) PNA-DNA duplexes (10 or 15 base-pairs) and a PNA2/DNA triplex with the DNA binding reagents distamycin A, 4',6-diamidino-2-phenylindole (DAPI), ethidium bromide, 8-methoxy-psoralen and the delta and lambda enantiomers of Ru(phen)2-dppz2+ have been investigated using optical spectroscopic methods. The behaviour of these reagents versus two PNA-PNA duplexes has also been investigated. With triple helical poly(dA)/(H-T10-Lys-NH2)2 no significant intercalative binding was detected for any of the DNA intercalators, whereas DAPI, a DNA minor groove binder, was found to exhibit a circular dichroism with a positive sign and amplitude consistent with minor groove binding. Similarly, a PNA-DNA duplex containing a central AATA motif, a typical minor groove binding site for the DNA minor groove binders distamycin A and DAPI, showed binding for both of these drugs, though with strongly reduced affinity. No important interactions were found for any of the ligands with a PNA-DNA duplex consisting of a ten base-pair mixed purine-pyrimidine sequence with only two AT base-pairs in the centre. Nor did any of the ligands show any detectable binding to the PNA-PNA duplexes (one containing an AATT motif). Various PNA derivatives with extentions of the backbone, believed to increase the flexibility of the duplex to opening of an intercalation slot, were tested for intercalation of ethidium bromide or 8-methoxypsoralen into the mixed sequence PNA-DNA duplex, however, without any observation of improved binding. The importance of the ionic contribution of the deoxyribose phosphate backbone, versus interactions with the nucleobases, for drug binding to DNA is discussed in the light of these findings.  相似文献   

9.
10.
Summary In an attempt to identify pancreatic islet cells emitting formaldehyde-induced fluorescence (FIF), the pancreatic islets of the domestic fowl were studied by combined fluorescence, ultrastructural, silver-impregnation and immunohistochemical methods in the same section or in consecutive semi-thin and ultra-thin sections. The results indicate that islet cells emitting intense FIF exhibit a strongly argyrophil reaction with the Grimelius' silver method and also immunohistochemical reaction with anti-glucagon serum, but not with anti-5-HT serum. Therefore, the fowl islet A cell, a peptide hormone-producing cell, stores simultaneously catecholamine as biogenic amine. The islet B and D cells did not display any FIF, any argyrophil reaction with the Grimelius' silver method, or any immunoreactivity with anti-glucagon or anti-5-HT sera. The fluorescent but non-argyrophil cells dispersed in the exocrine acinus may well be PP cells.  相似文献   

11.
Mandrioli M  Manicardi GC 《Hereditas》2003,138(2):129-132
In order to go in depth into the analysis of holocentric chromosome structure, atomic force microscopy (AFM) was applied to metaphase plates of the aphid Megoura viciae. AFM showed that aphid chromatids adhere to one another without any prominent structure detectable between them and without any evidence of chromosomal constrictions. AFM thus provided new and reliable evidences at a nanomolecular level concerning the holocentric structure of aphid chromosomes, without any of the artefacts due to sample staining or coating that are usually associated with electron microscopy.  相似文献   

12.
S Mabrey  I M Klotz 《Biochemistry》1976,15(1):234-242
The conformation of the gonadotropin releasing hormone (Gn-RH), whose primary sequence is pGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-GlyNH2, and of several of its structural analogues has been studied by circular dichroism, optical rotatory dispersion, and fluorescence spectroscopy. The effects of pH, guanidine, and temperature on fluorescence emission have also been examined. Titration data demonstrate that the histidine and tyrosine residues are free of any mutual interactions. The similarity of emission spectra in water and in guanidine hydrochloride solutions precludes significant interactions between the fluorescent groups and other residues. Neither the temperature nor the pH profiles of the emission intensities of either tyrosine or tryptophan reveal any fixed secondary structure in Gn-RH. Both the extent of alkaline quenching and the distance of 10-11 A calculated from F?rster energy transfer theory are in accord with a randomly coiled structure with only one residue between tyrosine and tryptophan. Furthermore, the circular dichroism spectrum and optical rotatory dispersion do not exhibit any contributions from peptide bonds in an ordered structure, although there is a perturbation of the peptide absorption region due to overlapping bands from side-chain chromophores. Gn-RH, therefore, appears to behave as a random coil polypeptide in water devoid of any intrachain residue interactions. This nonordered structure in Gn-RH and the lack of any significant differences in the physical-chemical properties of the hormone analogues indicate that a predetermined solution conformation is not required for biological activity. In contrast to its behavior in water, Gn-RH in trifluoroethanol exhibits a conformational transition, with the formation of a beta structure. Differences in conformational changes exhibited by several analogues in trifluoroethanol may be relevant to their relative biological activities at the receptor site.  相似文献   

13.
Waghmare SK  Caputo V  Radovic S  Bruschi CV 《BioTechniques》2003,34(5):1024-8, 1033
Sophisticated genome manipulation requires the possibility to modify any intergenic or intragenic DNA sequence at will, without leaving large amounts of undesired vector DNA at the site of alteration. To this end, a series of vectors was developed from a previous gene knockout plasmid system to integrate nonselectable foreign DNA at any desired genomic location in yeast, with a minimum amount of residual plasmid DNA. These vectors have two mutated Flp recognition targets (FRT) sequences flanking the KanMX4 gene and multiple sites for subcloning the DNA fragment to be integrated. The selectable marker can be recycled by Flp site-specific excision between the identical FRTs, thereby allowing the integration of further DNA fragments. With this system, the NLS-tetR-GFP and DsRed genes were successfully integrated at the thr1 locus, and the RVB1 gene was tagged at the C-terminus with the V5-epitope-6-histidine tag. This plasmid system provides for a new molecular tool to integrate any DNA fragment at any genome location in [cir+] yeast strains. Moreover, the system can be extrapolated to other eukaryotic cells in which the FLP/FRT system functions efficiently.  相似文献   

14.
Lactulose has profound health benefits by way of increasing bifidobacterial flora in the intestine of infants thereby protecting them against enteric infection, constipation and systemic encephalopathy. In the present study to assess the sub chronic toxicity of lactulose syrup, the rats were fed on a basal feed supplemented with lactulose syrup at 0.5, 1.0, 2.0 and 5.0% for a period of 21 weeks. Monitoring of food consumption, gain in body weight and physical observations did not reveal any treatment-related toxicity in any of the group of rats. Terminal autopsy also did not reveal any signs of toxicity. Further, no significant alterations in relative organ weight, serum biochemistry and urinalysis were observed up to 1% lactulose supplementation level. The results suggest that supplementation of lactulose in the diet does not produce any toxicity at the doses tested.  相似文献   

15.
Aspiration of vomitus is one of the leading causes of anesthetic deaths. These deaths can be prevented only by proper evaluation of the patient preoperatively and assuming that any patient dealt with in emergency has a full stomach until proven otherwise. Preliminary observations on the incidence of "silent regurgitation and aspiration" in a series of patients anesthetized for elective operation indicated that by obtaining a smooth induction and preventing any respiratory obstruction during anesthesia, regurgitation and aspiration can be minimized.  相似文献   

16.
Mass spectrometry-based quantitative proteomics has become an important component of biological and clinical research. Although such analyses typically assume that a protein's peptide fragments are observed with equal likelihood, only a few so-called 'proteotypic' peptides are repeatedly and consistently identified for any given protein present in a mixture. Using >600,000 peptide identifications generated by four proteomic platforms, we empirically identified >16,000 proteotypic peptides for 4,030 distinct yeast proteins. Characteristic physicochemical properties of these peptides were used to develop a computational tool that can predict proteotypic peptides for any protein from any organism, for a given platform, with >85% cumulative accuracy. Possible applications of proteotypic peptides include validation of protein identifications, absolute quantification of proteins, annotation of coding sequences in genomes, and characterization of the physical principles governing key elements of mass spectrometric workflows (e.g., digestion, chromatography, ionization and fragmentation).  相似文献   

17.
We have developed a novel version of the Achilles' Cleavage (AC) reaction in which virtually any restriction site on DNA of any size can be converted to a unique cleavage site. We first polymerized RecA protein on a synthetic oligodeoxyribonucleotide (oligo) in the presence of a nonhydrolyzable ATP analogue to generate oligo:RecA nucleoprotein filaments. These filament were then incubated with plasmid or intact chromosomal DNA from Saccharomyces cerevisiae to form stable complexes in the yeast LEU2 gene at the target sequence identical (or complementary) to that of the oligo. When HhaII (HinfI) methyltransferase (M.HhaII) was added, all of the recognition sites for HhaII with the exception of the one protected by the RecA filament were methylated and thus no longer cleaved by the cognate restriction endonuclease (HinfI). After inactivation of the RecA and the M.HhaII, HinfI was used to efficiently cleave the plasmid or chromosome specifically at the targeted restriction site. Since oligos specific for any sequence can be easily synthesized and the other reagents necessary to perform RecA-mediated AC (RecA-AC) reactions on both plasmids and intact chromosomes are readily available, this procedure can be applied immediately to the precise dissection and analysis of genomic DNA from any source and to any other research problem requiring efficient, highly specific cleavage of DNA at predetermined sites.  相似文献   

18.
The cumulant generating function and first two moments are derived for the stochastic distribution of units in a general irreversiblen-compartment model with time-dependent transition probabilities. In this model, a unit in the first compartment can transfer to any one of the remainingn−1 compartments and a unit in the second compartment can transfer to any of the remainingn−2 compartments and so on. In addition, a unit can enter or leave the system through any compartment. The work is related to previous research and a numerical example is given.  相似文献   

19.
Antiviral and antiproliferative activities of three naturally occurring components of leukocyte-derived human interferon (HuIFN-α) separated by concanavalin A-agarose affinity chromatography were studied in a variety of neoplastic cell lines. Significant differences were seen with these different components. The results strongly suggest that careful consideration must be given while selecting any one component of HuIFN-α for any of the antiviral or antiproliferative studies. There is no clear evidence that glycosylation of HuIFN-α has any significant influence on its in vitro antiviral or antiproliferative activities, although apparently glycosylated and non-glycosylated components gave different antiviral and antiproliferative responses in different tumor cells.  相似文献   

20.
We extend the concept of neighborhood invader strategy (NIS) to finite-dimensional matrix games and compare this concept to the evolutionarily stable strategy (ESS) concept. We show that these two concepts are not equivalent in general. Just as ESS's may not be unique, NIS's may also not be unique. However, if there is an ESS and a NIS then these strategies must be the same. We show that an ESNIS (an ESS and NIS) for any matrix game is unique and that a mixed ESS with full support is a NIS. Thus a mixed ESS with full support is not invadable by any pure or mixed strategy and it can invade any pure or mixed strategy. An ESS which is an ESNIS, therefore, has better chance of being established evolutionarily through dynamic selection.  相似文献   

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