Four rumen and duodenum cannulated, Holstein lactating cows were used in a change-over design to determine the effects of NaOH, formaldehyde (HCHO) or urea treated barley on disappearance of dry matter (DM), crude protein (CP), amino acids (AA), NDF, ADF and starch of barley in the rumen, post-abomasal (PAT) and total tract by the mobile nylon bag technique. Experimental treatments were coarse milled barley, barley treated with 35 g NaOH/kg, barley treated with 4 g formaldehyde/kg and barley treated with 35 g urea/kg, in which all chemical treated barley was milled coarse before feeding.
NaOH treatment reduced concentrations of lysine and cystine in the barley grain. All chemical treatments decreased rumen disappearances of barley CP but only NaOH and formaldehyde treatments also decreased total AA and some of the AA disappearances in the rumen. All chemical treatments increased DM, OM, CP, starch, NDF and ADF disappearance of barley in the PAT, but only NaOH and formaldehyde treatments increased total AA and most individual AA disappearances in the PAT. Chemical treatments increased disappearance of starch, methionine and glycine in the total tract (P<0.05).
Rumen disappearance of TAA was lower than for CP but PAT disappearance of TAA was more than for CP and finally total tract disappearance of TAA was more than for CP. Individual AA in barley disappeared at different rates in the rumen and PAT. Consequently, the proportion of digesta CP and AAs of barley, entering the intestine were changed by the chemical treatments. We concluded that, appropriate treatment of barley with NaOH or HCHO were provided substantial protection of CP and individual AA from rumen digestion and increased disappearance of most of barley nutrients in PAT, but, NaOH treatment reduced the AA quality of barley. Consequently, formaldehyde can therefore be considered better than NaOH and urea for treatment of barley grain. 相似文献
The human D5 monoclonal antibody binds to the highly conserved hydrophobic pocket on the N-terminal heptad repeat (NHR) trimer of HIV-1 gp41 and exhibits modest yet relatively broad neutralization activity. Both binding and neutralization depend on residues in the complementarity determining regions (CDRs) of the D5 IgG variable domains on heavy chain (VH) and light chain (VL). In an effort to increase neutralization activity to a wider range of HIV-1 strains, we have affinity matured the parental D5 scFv by randomizing selected residues in 5 of its 6 CDRs. The resulting scFv variants derived from four different CDR changes showed enhanced binding affinities to gp41 NHR mimetic (5-helix) which correlated to improved neutralization potencies by up to 8-fold. However, when converted to IgG1s, these D5 variants had up to a 12-fold reduction in neutralization potency over their corresponding scFvs despite their slightly enhanced in vitro binding affinities. Remarkably, D5 variant IgG1s bearing residue changes in CDRs that interact with epitope residues N-terminal to the hydrophobic pocket (such as VH CDR3 and VL CDR3) retained more neutralization potency than those containing residue changes in pocket-interacting CDRs (such as VH CDR2). These results provide compelling evidence for the existence of a steric block to an IgG that extends to the gp41 NHR hydrophobic pocket region, and can be a useful guide for developing therapeutic antibodies and vaccines circumventing this block. 相似文献
Wood samples (Picea jezoensis Carr.) were treated with aqueous NaOH solutions (0-0.20 concentration fraction, 12 conditions), and bending tests were performed to measure stress relaxation. The relationship between mechanical properties and NaOH concentration is discussed. The relaxation modulus and relaxation rate were divided into three concentration ranges. Both decreased slightly for NaOH concentrations less than 0.10, decreased drastically for concentrations between 0.11 and 0.14, and decreased slightly for concentrations greater than 0.15. The change in relaxation behavior upon NaOH treatment was due to an increase in molecular chain mobility in non-crystallized regions along the microfibril longitudinal axis in wood as well as lignin swelling. Furthermore, the molecular chain response in this region required time; thus, the dependence of crystallinity on the relaxation rate was apparent in the long time region. 相似文献
ABSTRACT Knowledge of the distribution and pathology of West Nile virus (WNV) in black bears is a necessary tool that allows wildlife managers to implement a management plan, set harvest quotas, and relocate nuisance bears. We studied the presence and significance of WNV titers in free-roaming black bears (Ursus americanus) in northeastern Wisconsin between February 2003 and March 2005. Serum neutralizing antibodies to WNV, with confirmation by plaque-reduction neutralization test to both WNV and Saint Louis encephalitis, identified exposure in 13 of 74 (17.6%) bears. This compares with a 6% infection rate in black bears in Virginia and 22% in European brown bears (Ursus arctos). Pathologic effects from exposure to WNV were not seen in any of the black bears studied. 相似文献
Hepatitis C virus (HCV) heterogeneity accounts for the failure of effective vaccine development and the lack of successful anti-viral therapy in some patients. Little is known about the immune response to HCV peptides and the region or race specific genotypes in China. The objective of this study was to characterize HCV antibody immune response to HCV peptides and HCV genotypes in different regions and races of China. A total of 363 serum samples were collected from HCV carriers in 6 regions in China. The immune response to HCV peptides was evaluated by ELISA. HCV genotypes were examined using nested RT-PCR. We found that the anti-HCV antibody neutralization rates were significantly different among the serum samples from different areas or from different races in the same area. For samples from Tibet and Sinkiang, the rates of neutralization by HCV peptides were only 3.2% and 30.8%, respectively. The genotypes of samples from Tibet and Sinkiang were apparently heterogeneic and included type I, II, III and multiple types (I/II/III, I/II, I/III, II/III). One specific sample with multiple-genotype (I/II/III) HCV infection was found to consist of type I, II, III, II/III and an unclassified genotype. These studies indicate that the anti-HCV antibody immune response to HCV peptides varied across regions and among races. The distribution of HCV genotypes among Tibetans in Tibet and Uighurs in Sinkiang was different from that in the inner areas of China. In addition, a “master” genotype, type II, was found to exist in HCV infection with multiple HCV genotypes. 相似文献