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1.
A stable subunit of Maackia amurensis leukoagglutinin (MMAL) was prepared by the selective reduction of disulfide bridges between the subunits followed by alkylation with 4-vinylpyridine. MMAL failed to precipitate fetuin, whereas it retained its ability to bind to the same glycoprotein coated on a plastic plate, indicating the monovalency of this derivative. This binding to immobilized fetuin was inhibited by a haptenic sugar, Neu5Ac alpha 2-3lactose, with the same inhibitory potency as against the native M. amurensis leukoagglutinin. Microscopic observation as well as flow cytometric analyses showed that Chinese hamster ovary cells were clearly stained with fluorescein isothiocyanate-labeled MMAL without any detectable agglutination. This staining was inhibited by the addition of fetuin or by the sugar chains of fetuin. Differences in the types of sialylated glycoconjugates on the cell surface of several cell lines were detected by the combined use of fluorescein isothiocyanate-labeled MMAL and the monomeric derivative of elderberry bark lectin (specific for the Neu5Ac alpha 2-6Gal/GalNAc sequence) by flow cytometry. These results demonstrate the usefulness of these monovalent derivatives of sialylated oligosaccharide-specific lectins as probes for the analysis of cell surface glycoconjugates containing sialic acid by the technique of flow cytometry. 相似文献
2.
KL Gatford TP Fletcher IJ Clarke PC Owens KJ Quinn PE Walton PA Grant BJ Hosking AR Egan EN Ponnampalam 《Canadian Metallurgical Quarterly》1996,74(6):1314-1325
The effects of sex and age on patterns of circulating somatotropin (ST) concentration and plasma IGF-I, IGF-II, insulin, and IGF binding protein-3 (IGFBP-3) were studied in ram, wether, and ewe lambs (n = 7 or 8) sampled at mean ages of 81 (I1) and 158 d (I2). Between 81 and 158 d of age, rams grew more rapidly than wethers (P < .01), and wethers grew more rapidly than ewes (P < .01). The sex differences in growth were reflected in empty body weight at slaughter: rams > wethers > ewes (P < .05). Mean plasma ST concentrations, ST pulse amplitude, and integrated plasma ST concentrations were greater (P < .05) in rams than in ewes at I1 and I2. Characteristics of the ST plasma profile in wethers were generally intermediate between those of rams and ewes. The interpulse interval was greater in ewes than in wethers at I2. The IGF-I and IGFBP-3 concentrations were greater in rams than in ewes at both sampling times. Plasma IGF-II was greater in ewes than in rams at I2. Mean plasma ST was approximately two thirds less at I2 than at I1 regardless of sex. Mean plasma ST and IGF-I at both ages were positively correlated with growth. Mean plasma ST at I2 was negatively correlated with fatness at slaughter. Sex and age significantly affected patterns of circulating ST and concentrations of IGF-I and IGFBP-3 in prepubertal growing lambs, under conditions for which growth rates and composition were also sexually dimorphic. 相似文献
3.
JJ Bull MR Badgett HA Wichman JP Huelsenbeck DM Hillis A Gulati C Ho IJ Molineux 《Canadian Metallurgical Quarterly》1997,147(4):1497-1507
Replicate lineages of the bacteriophage phiX 174 adapted to growth at high temperature on either of two hosts exhibited high rates of identical, independent substitutions. Typically, a dozen or more substitutions accumulated in the 5.4-kilobase genome during propagation. Across the entire data set of nine lineages, 119 independent substitutions occurred at 68 nucleotide sites. Over half of these substitutions, accounting for one third of the sites, were identical with substitutions in other lineages. Some convergent substitutions were specific to the host used for phage propagation, but others occurred across both hosts. Continued adaptation of an evolved phage at high temperature, but on the other host, led to additional changes that included reversions of previous substitutions. Phylogenetic reconstruction using the complete genome sequence not only failed to recover the correct evolutionary history because of these convergent changes, but the true history was rejected as being a significantly inferior fit to the data. Replicate lineages subjected to similar environmental challenges showed similar rates of substitution and similar rates of fitness improvement across corresponding times of adaptation. Substitution rates and fitness improvements were higher during the initial period of adaptation than during a later period, except when the host was changed. 相似文献
4.
5.
Activated calpain I immunoreactivity (76 kDa band) was detected in membranes prepared from rat brain hippocampal slices using a polyclonal antiserum raised against an N-terminus peptide of the cleaved subunit of calpain I. While basal levels of activated calpain I were stable over incubation times, 1 nM dopamine (DA) produced an initial 32% increase (5 min) in the 76 kDa protein followed by a 53% decrease in this band at 20 min of incubation. The DA-induced changes in activated calpain I immunoreactivity were blocked by the calpain inhibitor peptide, N-acetyl-Leu-Leu-norleucinal(100 microM) or by EGTA. Basal levels of the 76 kDa band were not affected by the calpain inhibitor. These changes in activated calpain I, elicited by DA, are in accord with the DA-induced decreases in the levels of the calpain substrate, gamma PKC (Yurko-Mauro and Friedman; J Cell Biochem [Abstr] 180:80, 1994; J Neurochem 65: 1622-1630, 1995) and suggest that DA activates this Ca(++)-dependent protease in its regulation of neuronal signal transduction. 相似文献
6.
ME Mendelsohn DH Abramson T Madden W Tong HT Tran IJ Dunkel 《Canadian Metallurgical Quarterly》1998,116(9):1209-1212
OBJECTIVES: To investigate the concentrations of carboplatin and etoposide achieved in the aqueous and vitreous humors after intravenous infusion in nonhuman primates, and to investigate whether local administration of carboplatin might result in higher concentrations in the vitreous humor. METHODS: Macaca fascicularis primates were treated with 1 of 3 regimens: (1) intravenous carboplatin (18.7 mg/kg), etoposide (5 mg/kg), and vincristine sulfate (0.05 mg/kg), (2) peribulbar carboplatin (10 mg/mL), or (3) episcleral balloon carboplatin (10 mg/mL). Concentrations of chemotherapeutic agents were measured in the plasma and in the aqueous and vitreous humors. RESULTS: No measurable amount of etoposide was detected in the aqueous or vitreous humor after intravenous administration. Mean measured peak vitreous concentration of carboplatin after intravenous administration was 0.31 microg/mL, which was 1% of the peak plasma value. Mean measured peak vitreous concentrations of carboplatin after peribulbar or episcleral balloon administration were 2.38 microg/mL and 2.95 microg/mL, respectively, which represent 7.68- and 9.52-fold increases over the concentration achieved after intravenous administration. No serious toxic effect was observed in any animal. CONCLUSIONS: Peribulbar and episcleral balloon administration of carboplatin seemed to be safe and resulted in higher vitreous concentrations than intravenous administration in this model. These results suggest that these alternate routes of delivery should be explored in children with vitreous seeding of retinoblastoma. 相似文献
7.
A prospective clinical trial comparing adverse postmyelographic effects and myelographic quality of metrizamide and iohexol was conducted. Using a predetermined, randomized assignment, 24 horses exhibiting neurologic signs were administered either metrizamide (180 mgl/ml) or iohexol (180 mgl/ml) via cerebellomedullary puncture. Each horse was evaluated postmyelographically for adverse effects. Myelographic quality was assessed by a numerical scoring method. Adverse effects were observed more frequently with metrizamide (21) compared with iohexol (6) myelography (p < 0.05). Seizures, intensification of preexisting neurologic signs and prolonged anesthetic recovery were the most common complications after myelography. There was no difference in myelographic quality (p > 0.05). We conclude that iohexol is safer than metrizamide for equine myelography and that quality myelograms can be obtained with either contrast medium. 相似文献
8.
High concentrations of Zn2+ are found in presynaptic terminals of excitatory neurons in the CNS. Zn2+ can be released during synaptic activity and modulate postsynaptic receptors, but little is known about the possibility that Zn2+ may enter postsynaptic cells and produce dynamic changes in the intracellular Zn2+ concentration ([Zn2+]i). We used fura-2 and magfura-2 to detect the consequences of Zn2+ influx in cultured neurons under conditions that restrict changes in intracellular Ca2+ and Mg2+ concentrations. The resulting ratio changes for both dyes were reversed completely by the Zn2+ chelator, N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine, indicating that these dyes are measuring changes in [Zn2+]i. We found that fura-2 was useful in measuring small increases in [Zn2+]i associated with exposure to Zn2+ alone that may be mediated by a Na+/Ca2+ exchanger. Magfura-2, which has a lower affinity for Zn2+, was more useful in measuring larger agonist-stimulated increases in [Zn2+]i. The coapplication of 300 microM Zn2+ and 100 microM glutamate/10 microM glycine resulted in a [Zn2+]i increase that was approximately 40-100 nM in magnitude and could be inhibited by the NMDA receptor antagonist, MK-801 (30 microM), or extracellular Na+. This suggests that Zn2+ influx can occur through at least two different pathways, leading to varying increases in [Zn2+]i. These findings demonstrate the feasibility of measuring changes in [Zn2+]i in neurons. 相似文献
9.
10.
V. I. Ivashchenko P. E. A. Turchi A. Gonis L. A. Ivashchenko P. L. Skrynskii 《Metallurgical and Materials Transactions A》2006,37(12):3391-3396
We have carried out numerical ab initio calculations of the elastic constants for several cubic ordered structures modeling titanium carbonitride (TiCxN1−x) alloys. The calculations were performed using the full-potential linear augmented plane-wave method (FPLAPW) to calculate
the total energy as functions of volume and strain, after which the data were fit to the traditional Murnaghan equation of
state and to a polynomial function of strain to determine the formation energy; the bulk modulus; and the elastic constants
C
11, C
12 and C
44. The predicted equilibrium lattice parameters are slightly higher than those found experimentally (on average by 0.2 pct).
The computed formation energy indicates that the alloys are stable in the entire range of the carbon concentration x and the maximum stability is obtained for 0.5≤x≤0.75. The computed bulk modulus, the shear modulus G, and the Young’s modulus E are within approximately 2, 1, and 2 pct of the experimentally measured characteristics, respectively. The maximum deviation
is observed for TiC and TiN. The moduli G, E, and Poisson’s ratio reach a maximum value at approximately the middle of the concentration range, which is due to the fact
that the shear modulus C
44 shows a maximum value for a valence electron concentration (VEC) in the range of 8.25 to 8.5. The other shear modulus (C
11−C
12)/2 does not exhibit any maximum overall concentration range and instead has a flat dependence in the range mentioned previously.
Such a concentration behavior of the elastic constants is related to specific changes in the band structure of TiCxN1−x alloys caused by the orthorhombic and monoclinic strains that determine the shear moduli (C
11−C
12)/2 and C
44, respectively.
This article is based on a presentation made in the symposium entitled “Fourth International Alloy Conference”, which occurred
in Kos, Greece, from June 26 to July 1, 2005, and was sponsored by Engineering Conferences International (ECI) and co-sponsored
by Lawrence Livermore National Laboratory and Naval Research Laboratory, United Kingdom. 相似文献