782 research outputs found
No association between islet cell antibodies and coxsackie B, mumps, rubella and cytomegalovirus antibodies in non-diabetic individuals aged 7â19 years
Viral antibodies were tested in a cohort of 44 isletcell antibody-positive individuals age 7â19 years, and 44 of their islet cell antibody-negative age and sex-matched classmates selected from a population study of 4208 pupils who had been screened for islet cell antibodies. Anti-coxsackie B1-5 IgM responses were detected in 14 of 44 (32%) of the islet cell antibody-positive subjects and in 7 of 44 (16%) control subjects. This difference did not reach the level of statistical significance. None of the islet cell antibody-positive subjects had specific IgM antibodies to mumps, rubella, or cytomegalovirus. There was also no increase in the prevalence or the mean titres of anti-mumps-IgG or IgA and anti-cytomegalovirus-IgG in islet cell antibody-positive subjects compared to control subjects. These results do not suggest any association between islet cell antibodies, and possibly insulitis, with recent mumps, rubella or cytomegalo virus infection. Further studies are required to clarify the relationship between islet cell antibodies and coxsackie B virus infections
Toolbox model of evolution of metabolic pathways on networks of arbitrary topology
In prokaryotic genomes the number of transcriptional regulators is known to
quadratically scale with the total number of protein-coding genes. Toolbox
model was recently proposed to explain this scaling for metabolic enzymes and
their regulators. According to its rules the metabolic network of an organism
evolves by horizontal transfer of pathways from other species. These pathways
are part of a larger "universal" network formed by the union of all
species-specific networks. It remained to be understood, however, how the
topological properties of this universal network influence the scaling law of
functional content of genomes. In this study we answer this question by first
analyzing the scaling properties of the toolbox model on arbitrary tree-like
universal networks. We mathematically prove that the critical branching
topology, in which the average number of upstream neighbors of a node is equal
to one, is both necessary and sufficient for the quadratic scaling. Conversely,
the toolbox model on trees with exponentially expanding, supercritical topology
is characterized by the linear scaling with logarithmic corrections. We further
generalize our model to include reactions with multiple substrates/products as
well as branched or cyclic metabolic pathways. Unlike the original model the
new version employs evolutionary optimized pathways with the smallest number of
reactions necessary to achieve their metabolic tasks. Numerical simulations of
this most realistic model on the universal network from the KEGG database again
produced approximately quadratic scaling. Our results demonstrate why, in spite
of their "small-world" topology, real-life metabolic networks are characterized
by a broad distribution of pathway lengths and sizes of metabolic regulons in
regulatory networks.Comment: 34 pages, 9 figures, 2 table
Determination of Cr, Fe, Co, Ni, Cu, Zn, As and Pb in liquid chemical waste by energy dispersive X-ray fluorescence
Evolution under Fluctuating Environments Explains Observed Robustness in Metabolic Networks
A high level of robustness against gene deletion is observed in many organisms. However, it is still not clear which biochemical features underline this robustness and how these are acquired during evolution. One hypothesis, specific to metabolic networks, is that robustness emerges as a byproduct of selection for biomass production in different environments. To test this hypothesis we performed evolutionary simulations of metabolic networks under stable and fluctuating environments. We find that networks evolved under the latter scenario can better tolerate single gene deletion in specific environments. Such robustness is underlined by an increased number of independent fluxes and multifunctional enzymes in the evolved networks. Observed robustness in networks evolved under fluctuating environments was âapparent,â in the sense that it decreased significantly as we tested effects of gene deletions under all environments experienced during evolution. Furthermore, when we continued evolution of these networks under a stable environment, we found that any robustness they had acquired was completely lost. These findings provide evidence that evolution under fluctuating environments can account for the observed robustness in metabolic networks. Further, they suggest that organisms living under stable environments should display lower robustness in their metabolic networks, and that robustness should decrease upon switching to more stable environments
Natural gaits of the non-pathological flat foot and high-arched foot
There has been a controversy as to whether or not the non-pathological flat
foot and high-arched foot have an effect on human walking activities. The 3D
foot scanning system was employed to obtain static footprints from subjects
adopting a half-weight-bearing stance. Based upon their footprints, the
subjects were divided into two groups: the flat-footed and the high-arched. The
plantar pressure measurement system was used to measure and record the
subjects' successive natural gaits. Two indices were proposed: distribution of
vertical ground reaction force (VGRF) of plantar and the rate of the footprint
areas. Using these two indices to compare the natural gaits of the two subject
groups, we found that (1) in stance phase, there is a significant difference
(p<0.01) in the distributions of VGRF of plantar; (2) in a stride cycle, there
is also a significant difference (p<0.01) in the rates of the footprint areas.
Our analysis suggests that when walking, the VGRF of the plantar brings greater
muscle tension to the flat-footed while a smaller rate of the footprint areas
brings greater stability to the high-arched.Comment: 8 pages, 4 figure
Evaluation of PCR on Bronchoalveolar Lavage Fluid for Diagnosis of Invasive Aspergillosis: A Bivariate Metaanalysis and Systematic Review
BACKGROUND: Nucleic acid detection by polymerase chain reaction (PCR) is emerging as a sensitive and rapid diagnostic tool. PCR assays on serum have the potential to be a practical diagnostic tool. However, PCR on bronchoalveolar lavage fluid (BALF) has not been well established. We performed a systematic review of published studies to evaluate the diagnostic accuracy of PCR assays on BALF for invasive aspergillosis (IA). METHODS: Relevant published studies were shortlisted to evaluate the quality of their methodologies. A bivariate regression approach was used to calculate pooled values of the method sensitivity, specificity, and positive and negative likelihood ratios. Hierarchical summary receiver operating characteristic curves were used to summarize overall performance. We calculated the post-test probability to evaluate clinical usefulness. Potential heterogeneity among studies was explored by subgroup analyses. RESULTS: Seventeen studies comprising 1191 at-risk patients were selected. The summary estimates of the BALF-PCR assay for proven and probable IA were as follows: sensitivity, 0.91 (95% confidence interval (CI), 0.79-0.96); specificity, 0.92 (95% CI, 0.87-0.96); positive likelihood ratio, 11.90 (95% CI, 6.80-20.80); and negative likelihood ratio, 0.10 (95% CI, 0.04-0.24). Subgroup analyses showed that the performance of the PCR assay was influenced by PCR assay methodology, primer design and the methods of cell wall disruption and DNA extraction. CONCLUSIONS: PCR assay on BALF is highly accurate for diagnosing IA in immunocompromised patients and is likely to be a useful diagnostic tool. However, further efforts towards devising a standard protocol are needed to enable formal validation of BALF-PCR
Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV
The performance of muon reconstruction, identification, and triggering in CMS
has been studied using 40 inverse picobarns of data collected in pp collisions
at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection
criteria covering a wide range of physics analysis needs have been examined.
For all considered selections, the efficiency to reconstruct and identify a
muon with a transverse momentum pT larger than a few GeV is above 95% over the
whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4,
while the probability to misidentify a hadron as a muon is well below 1%. The
efficiency to trigger on single muons with pT above a few GeV is higher than
90% over the full eta range, and typically substantially better. The overall
momentum scale is measured to a precision of 0.2% with muons from Z decays. The
transverse momentum resolution varies from 1% to 6% depending on pseudorapidity
for muons with pT below 100 GeV and, using cosmic rays, it is shown to be
better than 10% in the central region up to pT = 1 TeV. Observed distributions
of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO
Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV
The performance of muon reconstruction, identification, and triggering in CMS
has been studied using 40 inverse picobarns of data collected in pp collisions
at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection
criteria covering a wide range of physics analysis needs have been examined.
For all considered selections, the efficiency to reconstruct and identify a
muon with a transverse momentum pT larger than a few GeV is above 95% over the
whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4,
while the probability to misidentify a hadron as a muon is well below 1%. The
efficiency to trigger on single muons with pT above a few GeV is higher than
90% over the full eta range, and typically substantially better. The overall
momentum scale is measured to a precision of 0.2% with muons from Z decays. The
transverse momentum resolution varies from 1% to 6% depending on pseudorapidity
for muons with pT below 100 GeV and, using cosmic rays, it is shown to be
better than 10% in the central region up to pT = 1 TeV. Observed distributions
of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO
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