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Chromium metabolism of lactating women was evaluated by measuring diet, breast milk, urine, and serum chromium in 17 subjects 60 d postpartum. Breast milk chromium concentration was similar for the 3 d of collection with a mean +/- SE concentration of 3.54 +/- 0.40 nmol/L (0.18 ng/mL). Dietary intake and urinary chromium values were also similar for each of the 3 collection days. Total chromium intake of lactating mothers (0.79 +/- 0.08 mumol/d) was greater than that of reference female subjects (0.48 +/- 0.02). There was a significant correlation (r = 0.84) between serum chromium and urinary chromium excretion. If a breast milk volume of 715 mL is assumed, chromium intake of exclusively breast-fed infants is < 2% of the estimated safe and adequate daily intake of 10 micrograms. In summary, breast milk chromium content is independent of dietary chromium intake and serum or urinary chromium values. Chromium intake also did not correlate with serum or urine chromium but there was a significant relationship between serum and urinary chromium concentrations. 相似文献
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During the BOF process for the production of crude steel, the specific amount of dust emitted is of the order of 2 % of the steel weight at turn down. The process gas conveys the dust through the boiler system into the primary and secondary dust catchers. The transportation of dust particles is influenced by blowing parameters; physical properties of process gas and of dust phases; and, type and layout of the converter and the filter system. In this work, a numerical simulation model is developed that simulates the pneumatic conveyance and sedimentation of primarily coarse dust particles in the BOF gas cleaning system. Comparison is then made of predicted coarse dust characteristics with values for dust sampled from an existing plant in order to verify the plausibility of the developed model. 相似文献
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MB Spellerberg CJ Chapman CI Mockridge DA Isenberg FK Stevenson 《Canadian Metallurgical Quarterly》1995,6(2):52-56
The VH4-21 (V4-34) gene segment, a member of the VH4 family, is expressed early in B-cell maturation and is utilized by approximately 6% of normal adult B lymphocytes. This prevalence indicates an importance of VH4-21 in the B-cell repertoire. The gene also encodes certain autoantibodies being mandatory for pathological IgM anti-red cell antibodies directed against the I/i antigen, and also capable of encoding anti-DNA antibodies. Recognition of I/i antigen or DNA appears to be via two distinct sites on VH, with I/i binding mediated by sequences in the framework region, and DNA binding correlating with the presence of positively charged amino acids in complementarity-determining region 3. However, these positively charged residues appear to suppress the ability of the framework region to interact with I/i, rendering a single sequence monospecific for I/i or DNA. The IgM anti-DNA antibodies also recognize bacterial lipid A, whereas the anti-I/i antibodies do not, indicating that CDR3 may be involved in binding the negatively charged lipid A. Structural similarities between the DNA backbone and lipid A provide a possible explanation for this cross-reactivity. This dual recognition of bacterial antigen and autoantigen provides a potential link between infection and autoimmunity. 相似文献
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T Smith AK Hewson CI Kingsley JP Leonard ML Cuzner 《Canadian Metallurgical Quarterly》1997,150(6):1909-1917
Acute, monophasic experimental allergic encephalomyelitis (EAE) in the Lewis rat shows pathological similarities to the human disease multiple sclerosis (MS). Rats that recover from EAE are essentially resistant to disease reinduction, unlike MS in which relapses are frequently associated with common bacterial and viral infections. As macrophage-derived interleukin (IL)-12 is a critical component of innate resistance to bacterial infection and appears to directly activate encephalitogenic T cells in vivo, the ability of this cytokine to reinduce paralysis in EAE was examined. Paralytic disease was exacerbated by intraperitoneal IL-12 administration and could be reinduced up to 1 week after recovery from the primary clinical episode. Concomitant with worsening of initial clinical signs and relapse was an increase in the ratio of macrophages to T cells in brain stem perivascular cuffs and the expression of inducible nitric oxide synthase in cells with both macrophage and microglial morphology. These findings suggest that IL-12 may contribute to macrophage-mediated disease exacerbation and relapse in patients with MS. 相似文献
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Variation in repeated nucleotide sequences (RNSs) at the level of entire families assayed by Southern blot hybridization is remarkably low within species and is a powerful tool for scrutinizing the origin of allopolyploid taxa. Thirty-one clones from RNSs isolated from different Triticeae genera were used to investigate the genome constitution of South American Elymus. One of these clones, pHch2, preferentially hybridized with the diploid H genome Hordeum species. Hybridization of this clone with a worldwide collection of Elymus species with known genome formulas showed that pHch2 clearly discriminates Elymus species with the H genome (StH, StHH, StStH, and StHY) from those with other genome combinations (StY, StStY, StPY, and StP). Hybridization with pHch2 indicates the presence of the H genome in all South American Elymus species except Elymus erianthus and Elymus mendocinus. Hybridization with additional clones that revealed differential restriction fragments (marker bands) for the H genome confirmed the absence of the H genome in these species. Differential restriction fragments for the Ns genome of Psathyrostachys were detected in E. erianthus and E. mendocinus and three species of Leymus. Based on genome constitution, morphology, and habitat, E. erianthus and E. mendocinus were transferred to the genus Leymus. 相似文献
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