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431.
432.
The prevalence of oral colonization with C. albicans was studied in 40 children with acute lymphoblastic leukaemia (ALL) and 40 matched normal children. Colonization was more common in the ALL group (25% colonized) than the normal group (7.5% colonized). Total saliva IgA levels were lower in the ALL group, but low levels did not correlate with oral colonization. The three normal children with oral colonization all had anti-C. albicans IgA in their saliva, as had seven of the ten colonized ALL patients. 相似文献
433.
Kym Eden Ryan Morris Jay Gillam Cait?E. MacPhee Rosalind?J. Allen 《Biophysical journal》2015,108(3):632-643
Kinetic measurements of the self-assembly of proteins into amyloid fibrils are often used to make inferences about molecular mechanisms. In particular, the lag time—the quiescent period before aggregates are detected—is often found to scale with the protein concentration as a power law, whose exponent has been used to infer the presence or absence of autocatalytic growth processes such as fibril fragmentation. Here we show that experimental data for lag time versus protein concentration can show signs of kinks: clear changes in scaling exponent, indicating changes in the dominant molecular mechanism determining the lag time. Classical models for the kinetics of fibril assembly suggest that at least two mechanisms are at play during the lag time: primary nucleation and autocatalytic growth. Using computer simulations and theoretical calculations, we investigate whether the competition between these two processes can account for the kinks which we observe in our and others’ experimental data. We derive theoretical conditions for the crossover between nucleation-dominated and growth-dominated regimes, and analyze their dependence on system volume and autocatalysis mechanism. Comparing these predictions to the data, we find that the experimentally observed kinks cannot be explained by a simple crossover between nucleation-dominated and autocatalytic growth regimes. Our results show that existing kinetic models fail to explain detailed features of lag time versus concentration curves, suggesting that new mechanistic understanding is needed. More broadly, our work demonstrates that care is needed in interpreting lag-time scaling exponents from protein assembly data. 相似文献
434.
435.
S. F. Eden 《Journal of Zoology》1985,205(3):325-334
The breeding biology of magpies in an adjacent urban and rural area in the same year was compared. Breeding commenced earlier in the urban habitat. This was attributed to the earlier availability of invertebrate food in the urban habitat as a result of higher urban ambient temperature. Hatching success and the amount of nest predation were lower in the urban area than in the rural area. Low levels of nest predation in urban areas were due to reduced human predation and probably to the relatively low numbers of many natural predators. Differences in the nest tree species utilized also influenced the probability of human predation. Despite these differences in the causes of egg and chick mortality, the number of young reared to 14 days of age per nest was similar in both habitats. 相似文献
436.
437.
Michael J. Eden 《Human ecology: an interdisciplinary journal》1993,21(2):145-166
Ecological aspects of traditional swidden cultivation by Bine- speaking groups in wetland areas of lowland southwest Papua New Guinea are examined. A notable feature of the area is the coexistence of extensive, polycultural forest cultivation and more intensive, specialized savanna cultivation. Both agrosystems occur on soils of inherently similar properties. The savanna vegetation is secondary in character and, once established, is better suited to more intensive swidden cultivation based on taro (Colocasia esculenta). The agrosystems in question represent stages in the local development of agriculture, and, although multiple causes of intensification may be involved, the study confirms that lowland, as well as highland, areas of New Guinea have provided development opportunities for traditional cultivators. 相似文献
438.
Abstract The non-secretor phenotype was significantly associated with the occurrence of renal scarring among patients with recurrent pyelonephritis. Girls ( n = 77) with recurrent pyelonephritis were followed from the first known episode of infection for up to twelve years with repeated radiological investigations. They were divided into two categories: those with renal scars ( n = 35) and those who did not develop scars ( n = 42). There was a significant over-representation of non-secretors among the patients with scarring, (14/35, 40%) compared to the healthy controls (21.8%, P < 0.05). The frequency of non-secretors among the girls who did not develop scars in spite of repeated episodes of acute pyelonephritis was not significantly different from the healthy controls (9/42, 21%, n.s.). This study provides a basis for analysis of the influence of secretor state on host-parasite interaction in the urinary tract. 相似文献
439.
Transient electric birefringence measurements of the rotational diffusion constant of five short restriction fragments of the plasmid pBR322 show that the hydrodynamic length is independent of sodium ion concentration in the range of 0.2 to 2.5 mM. The fragments are too stiff to be modeled as wormlike molecules. The rotational relaxation times of the fragments, which range from 64 to 124 base pairs, have been used to calculate the rise per base pair using six different theoretical expressions for the length dependence of the rotational diffusion coefficient of straight cylinder. The best estimate for the rise per base pair of Na-DNA in solution is 3.3 ± 0.1 Å. 相似文献
440.
Berent Prakken Marca Wauben Peter van Kooten Steve Anderton Ruurd van der Zee Wietse Kuis Willem van Eden 《Biotherapy》1998,10(3):205-211
Adjuvant Arthritis (AA) can be induced in Lewis rats by immunisation with mycobacterial antigens. The disease can be passively
transferred with T cell clone A2b, which recognises the 180–188 amino acid sequence in mycobacterial heat shock protein 60
(hsp60) and which crossreacts with crude cartilage proteoglycans. We succeeded to induce peripheral tolerance to this AA-associated
T cell epitope following nasal administration of a peptide containing this epitope (mycobacterial hsp60 176–190). In rats
treated nasally with 176–190 and immunised with mycobacterial hsp60, proliferative responses to 176–190 were reduced. AA was
inhibited nasally with 176–190 treated rats and not in rats nasally treated with a control mycobacterial hsp60 peptide (211–225).
Moreover, nasal 176–190 led to similar arthritis protective effects in a non-microbially induced experimental arthritis (avridine
induced arthritis).
In a subsequent study we tried to prevent and to treat AA through nasal administration of mycobacterial hsp60 peptide 180–188
and a peptide analogue of 180–188, 180–188L183->A (Alanine 183), which has been shown to have an increased MHC-binding affinity for rat RT1 B1 and an increased capacity to inhibit the proliferative A2b responsein vitro.
We found that nasal administration of 180–188 had a moderate arthritis suppressive effect in AA, whereas its analogue peptide
Alanine 183, had a strong suppressive effect. This strong arthritis suppressive effect was only partly due to the higher MHC-binding
affinity for rat RT1 B1. Furthermore, it was possible to passively transfer nasal Alanine 183 induced disease protection. The present findings may
in our view offer novel prospects for immunotherapy through nasal administration of (analogue) peptides, with a mimicry relationship
with joint specific cartilage proteoglycan epitopes. 相似文献