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321.
322.
Guglietta S Beghetto E Spadoni A Buffolano W Del Porto P Gargano N 《Microbes and infection / Institut Pasteur》2007,9(2):127-133
Human infection with Toxoplasma gondii is generally asymptomatic in immunocompetent adults while it causes significant morbidity in congenitally infected children. Cell mediated immunity plays the main role in host resistance to T. gondii infection and a Th1 cytokine profile is necessary for protection and control of infection. The present work focused on comparing the helper T cell response to the GRA1 antigen of the parasite between children with congenital toxoplasmosis and healthy adults with acquired infection. We demonstrated that in young children with congenital infection the specific T cell response to parasite antigens is impaired and that such hypo-responsiveness is restored during childhood. Also, we provided clear evidence that in individuals with congenital toxoplasmosis the acquisition of functional helper T cell responses is disease-unrelated and indistinguishable in terms of strength, epitope specificity, and cytokine profile from the corresponding responses in immunocompetent adults with asymptomatic acquired T. gondii infection. 相似文献
323.
Porto TS Pessôa-Filho PA Neto BB Filho JL Converti A Porto AL Pessoa A 《Journal of industrial microbiology & biotechnology》2007,34(8):547-552
In order to reduce the toxicity of Clostridium perfringens fermentation broths used in vaccine preparation, we developed two-phase aqueous systems for removal of toxin-activating proteases.
Removal of the proteases inhibits the conversion of protoxin to active toxin. In order to establish the conditions under which
the phase separation occurs, binodal curves, formed by poly(ethylene glycol) (PEG) and sodium citrate, were investigated at
different values of pH and PEG molar mass. A 24-experimental design was used to evaluate the influence of PEG molar mass and concentration, citrate concentration and pH
on protease partition coefficient, removal factor and protease removal yield. It has been found that simultaneous increase
in PEG molar mass and decrease in citrate concentration remarkably improved the removal factor, whereas the protease removal
yield showed an opposite trend. The best conditions for the system under consideration (removal factor of 2.69 and yield of
116%) were obtained at pH 8.0 using PEG molar mass of 8000 g mol−1 and concentrations of PEG and citrate of 24 and 15%, respectively. 相似文献
324.
Marcelo Filonzi Laís C Cardoso Maristela T Pimenta Daniel BC Queiróz Maria CW Avellar Catarina S Porto Maria FM Lazari 《Reproductive biology and endocrinology : RB&E》2007,5(1):29
Background
Relaxin is the endogenous ligand of the G-protein coupled receptor RXFP1, previously known as LGR7. In humans relaxin can also activate, but with lower affinity, the closely related receptor for the insulin-like peptide from Leydig cells, RXFP2, previously known as LGR8. The lack of relaxin impairs male fertility but the precise distribution and the function of relaxin receptors in the male reproductive tract is not known. We investigated the distribution of Rxfp1 and Rxfp2 in the reproductive tract of the male rat and the function of relaxin in the vas deferens, a tissue with high expression of both receptors. 相似文献325.
Groups of genes that produce exopolysaccharide with a N-acetyl-D-glucosamine monomer are in the genome of several pathogenic bacteria. Chromobacterium violaceum, an opportunistic pathogen, has the operon hmsHFR-CV2940, whose proteins can synthesize such polysaccharide. In this work, multiple alignments among proteins from bacteria that synthesize such polysaccharide were used to verify the existence of amino acids that might be critical for pathogen activity. Three-dimensional models were generated for spatial visualization of these amino acid residues. The analysis carried out showed that the protein HmsR preserves the amino acids D135, D228, Q264 and R267, considered critical for the formation of biofilms and, furthermore, that these amino acids are close to each other. The protein HmsF of C. violaceum preserves the residues D86, D87, H156 and W115. It was also shown that these residues are also close to each other in their spatial arrangement. For the proteins HmsH and CV2940 there is evidence of conservation of the residues R104 and W94, respectively. Conservation and favorable spatial location of those critical amino acids that constitute the proteins of the operon indicates that they preserve the same enzymatic function in biofilm synthesis. This is an indicator that the operon hmsHFR-CV2940 is a possible target in C. violaceum pathogenicity. 相似文献
326.
Lenilson C. Rocha Hercules V. Ferreira Eli F. Pimenta Roberto G. S. Berlinck Mirna H. R. Seleghim Darci C. D. Javaroti Lara D. Sette Rafaella C. Bonugli André L. M. Porto 《Biotechnology letters》2009,31(10):1559-1563
The asymmetric reduction of 2-chloro-1-phenylethanone (1) by seven strains of marine fungi was evaluated and afforded (S)-(-)-2-chloro-1-phenylethanol with, in the best case, an enantiomeric excess of 50% and an isolated yield of 60%. The ability
of marine fungi to catalyse the reduction was directly dependent on growth in artificial sea water-based medium containing
a high concentration of Cl− (1.2 M). When fungi were grown in the absence of artificial sea water, no reduction of 1 by whole cells was observed. The biocatalytic reduction of 1 was more efficient at neutral rather than acidic pH values and in the absence of glucose as co-substrate. 相似文献
327.
Restriction-map variation with the yellow-achaete-scute region in five populations of Drosophila melanogaster 总被引:9,自引:0,他引:9
It has been proposed that the degree of recombination for a genomic region
will affect the level of both nucleotide heterozygosity and the density of
transposable elements. Both features of genomic diversity have been
examined in a number of recent reports for regions undergoing relatively
normal levels of recombination in Drosophila melanogaster. In this study
the genomic variation associated with yellow-achaete- scute loci located at
the tip of the X chromosome is examined by six- cutter restriction mapping.
In this region, as usual for regions adjacent to telomeres, crossing-over
is dramatically reduced, and published studies of visible mutants indicate
extremely little restriction-map variation. Eight six-cutter restriction
endonucleases were used to locate sequence variation in 14- and 16.5-kb
regions in 109 lines sampled from North America, Africa, and Europe. The
overall level of heterozygosity is estimated as 0.29%. Nine large
insertions, all presumed to be transposable elements, were observed.
Base-pair heterozygosity appears to be reduced compared with regions having
normal levels of recombination. The estimated heterozygosity is much higher
than reported in earlier studies of restriction-map variation among visible
mutations in the complex. The incidence of large insertions is not elevated
compared with that in other regions of the genome. This suggests that
asymmetric synapsis and exchange is not an important mechanism for the
elimination of transposable elements.
相似文献
328.
We have attempted to elucidate the natural history of pulmonary aspergillus intracavitary colonization (PAIC) based on more than 350 cases of the disease observed in the last 11 years and on data collected from the literature. The data indicate that PAIC is a dynamic process consequent to the continual growth and death of fungal elements and also with their relationships to the anatomic features of the cavity (valvular mechanisms, vascular alteration). The clinical presentations reflect immunological changes in the host. Metabolites produced by the species of Aspergillus involved affect the clinical presentation of the syndrome. 相似文献
329.
Graça Porto Helena Alves Pedro Rodrigues José M Cabeda Cristina Portal Anunciação Ruivo Benvindo Justiça Roger Wolff Maria De Sousa 《Immunogenetics》1998,47(5):404-410
The present study is an analysis of the frequencies of HFE mutations in patients with different forms of iron overload compared with the frequencies found in healthy subjects from
the same region. The frequencies of HLA-A and -B antigens and HLA haplotypes were also analyzed in the same subjects. The study population included: 71 healthy individuals; 39 genetically
and clinically well-characterized patients with genetic hemochromatosis (HH); and 25 patients with non-classical forms of
iron overload (NCH), excluding secondary hemochromatosis. All subjects were HLA-typed and HFE-genotyped by the oligonucleotide ligation assay (OLA). The gene frequencies found for the C282Y and H63D mutations of HFE were respectively: 0.03 and 0.23 in healthy individuals, 0.86 and 0.04 in HH patients, and 0.08 and 0.48 in NCH patients.
An expected significant association between HH and HLA-A3 was observed, which was found to be in linkage disequilibrium with
the C282Y mutation. A new association was seen, however, between HLA-A29 and NCH, in linkage disequilibrium with the H63D
mutation. Again as expected, the HLA-B antigen B7 was associated with HH in linkage disequilibrium with HLA-A3. In addition,
the HLA-B antigen B44 was found to be associated with NCH but not in linkage disequilibrium with either A29 or the H63D mutation.
In conclusion, a new association of the HFE H63D mutation with forms of hemochromatosis other than HH and a new association between the HLA phenotype A29 and the HFE H63D mutation were found in the same patients. These findings reinforce evidence for the involvement of the major histocompatibility
class I in iron metabolism, supporting the notion of a physiological role for the immunological system in the regulation of
iron load.
Received: 11 June 1997 / Revised: 29 October 1997 相似文献
330.
Six cases of pulmonary paracoccidioidomycosis diagnosed only by transthoracic fine needle aspiration are presented. The clinical
and radiological presentation is varied. The most frequent use of this technique will permit the diagnosis of early lesions
of mycosis.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献