Determinação das forças retentivas de bases de dentaduras de alumínio e resinas acrílicas

Apresentação de um trabalho de pesquisa, para determinação das diferenças entre os valores retentivos apresentados por bases de dentaduras confeccionadas de diferentes materiais. Ditos valores foram deterrninados e comparados sob diferentes condições. As bases de dentaduras foram confeccionadas de três materiais diferentes a partir de dois modelos diferentes quanto à características de superfície e para dois pacientes diversos. Como líquido intermediário utilizou-se saliva humana e água com diversos valores de tensão superficial, determinados. Os resultados trouxeram à luz vãrios fatores, tanto na bôca de pacientes como em modelos de laboratório, qüe influenciam a quantidade de rètenção apresentada pelas bases de dentaduras. Um estudo subseqüente de certos aspectos do problema de retenção de dentaduras completas é necessário para esclarecer alguns dos pontos abordados e discutidos neste trabalho.

An associated process for the purification of immuno globulin G, catalase, superoxide dismutase and albumin from haemolysed human placenta blood

The human placenta is a rich raw material for production of many biopharmaceutical products. Here we describe a co-purification process for the production of four different proteins from haemolysed human placenta blood: IgG, catalase (Cat), superoxide dismutase (Sod) and albumin (Alb). The process can be divided in two parts: the common steps and the specific separation techniques for each protein. The common steps are: extraction, haemoglobin precipitation, concentration/diafiltration and the first Q-Sepharose chromatography step. At this chromatography step the process is branched: while IgG and Cat were recovered in the flow-through, Sod and Alb were eluted separately. IgG and Cat were separated in a second Q-Sepharose chromatography step during which IgG was recovered in the flow-through, whereas Cat bound to the resin. IgG was purified by S-Sepharose chromatography, followed by selective precipitation with n-octanoic acid, yielding about 0.4 g of IgG per kg of placenta. Cat was eluted at the second Q-Sepharose chromatography step and was purified by Blue Sepharose chromatography. A total of 1.8 x 10(6) units of Cat were recovered/kg of placenta, with a specific activity of 45000 units/mg of protein. Sod was further purified by S-Sepharose and Phenyl-Sepharose chromatography steps and recovered in the non-adsorbed fractions. The yield of Sod was 2.1 x 10(5) units/kg of placenta, with a specific activity of 1194 units/mg of protein. Alb purification was followed by a combined process including thermocoagulation and treatment with activated charcoal. The final step was Phenyl-Sepharose chromatography. The process yielded 3.1 g of Alb/kg of placenta. The described methodology was designed to be easily scaled-up for industrial production.

The contribution of 700,000 ORF sequence tags to the definition of the human transcriptome

Open reading frame expressed sequences tags (ORESTES) differ from conventional ESTs by providing sequence data from the central protein coding portion of transcripts. We generated a total of 696,745 ORESTES sequences from 24 human tissues and used a subset of the data that correspond to a set of 15,095 full-length mRNAs as a means of assessing the efficiency of the strategy and its potential contribution to the definition of the human transcriptome. We estimate that ORESTES sampled over 80% of all highly and moderately expressed, and between 40% and 50% of rarely expressed, human genes. In our most thoroughly sequenced tissue, the breast, the 130,000 ORESTES generated are derived from transcripts from an estimated 70% of all genes expressed in that tissue, with an equally efficient representation of both highly and poorly expressed genes. In this respect, we find that the capacity of the ORESTES strategy both for gene discovery and shotgun transcript sequence generation significantly exceeds that of conventional ESTs. The distribution of ORESTES is such that many human transcripts are now represented by a scaffold of partial sequences distributed along the length of each gene product. The experimental joining of the scaffold components, by reverse transcription-PCR, represents a direct route to transcript finishing that may represent a useful alternative to full-length cDNA cloning.

A soxRS-constitutive mutation contributing to antibiotic resistance in a clinical isolate of Salmonella enterica (Serovar typhimurium)

The soxRS regulon is activated by redox-cycling drugs such as paraquat and by nitric oxide. The >15 genes of this system provide resistance to both oxidants and multiple antibiotics. An association between clinical quinolone resistance and elevated expression of the soxRS regulon has been observed in Escherichia coli, but this association has not been explored for other enteropathogenic bacteria. Here we describe a soxRS-constitutive mutation in a clinical strain of Salmonella enterica (serovar Typhimurium) that arose with the development of resistance to quinolones during treatment. The elevated quinolone resistance in this strain derived from a point mutation in the soxR gene and could be suppressed in trans by multicopy wild-type soxRS. Multiple-antibiotic resistance was also transferred to a laboratory strain of S. enterica by introducing the cloned mutant soxR gene from the clinical strain. The results show that constitutive expression of soxRS can contribute to antibiotic resistance in clinically relevant S. enterica.

Identification of human chromosome 22 transcribed sequences with ORF expressed sequence tags

Transcribed sequences in the human genome can be identified with confidence only by alignment with sequences derived from cDNAs synthesized from naturally occurring mRNAs. We constructed a set of 250,000 cDNAs that represent partial expressed gene sequences and that are biased toward the central coding regions of the resulting transcripts. They are termed ORF expressed sequence tags (ORESTES). The 250,000 ORESTES were assembled into 81,429 contigs. Of these, 1, 181 (1.45%) were found to match sequences in chromosome 22 with at least one ORESTES contig for 162 (65.6%) of the 247 known genes, for 67 (44.6%) of the 150 related genes, and for 45 of the 148 (30.4%) EST-predicted genes on this chromosome. Using a set of stringent criteria to validate our sequences, we identified a further 219 previously unannotated transcribed sequences on chromosome 22. Of these, 171 were in fact also defined by EST or full length cDNA sequences available in GenBank but not utilized in the initial annotation of the first human chromosome sequence. Thus despite representing less than 15% of all expressed human sequences in the public databases at the time of the present analysis, ORESTES sequences defined 48 transcribed sequences on chromosome 22 not defined by other sequences. All of the transcribed sequences defined by ORESTES coincided with DNA regions predicted as encoding exons by genscan. (http://genes.mit.edu/GENSCAN.html).

The genome sequence of the plant pathogen Xylella fastidiosa. The Xylella fastidiosa Consortium of the Organization for Nucleotide Sequencing and Analysis

Xylella fastidiosa is a fastidious, xylem-limited bacterium that causes a range of economically important plant diseases. Here we report the complete genome sequence of X. fastidiosa clone 9a5c, which causes citrus variegated chlorosis--a serious disease of orange trees. The genome comprises a 52.7% GC-rich 2,679,305-base-pair (bp) circular chromosome and two plasmids of 51,158 bp and 1,285 bp. We can assign putative functions to 47% of the 2,904 predicted coding regions. Efficient metabolic functions are predicted, with sugars as the principal energy and carbon source, supporting existence in the nutrient-poor xylem sap. The mechanisms associated with pathogenicity and virulence involve toxins, antibiotics and ion sequestration systems, as well as bacterium-bacterium and bacterium-host interactions mediated by a range of proteins. Orthologues of some of these proteins have only been identified in animal and human pathogens; their presence in X. fastidiosa indicates that the molecular basis for bacterial pathogenicity is both conserved and independent of host. At least 83 genes are bacteriophage-derived and include virulence-associated genes from other bacteria, providing direct evidence of phage-mediated horizontal gene transfer.

[Evaluation of an instrument for the classification of patients in four levels of dependency on nursing care]

This study presents the process of validation of a tool that classifies patients in four levels of dependence to the nursing care delivered at a University Hospital. The research gave to participants an opportunity to analyse patients' needs, showing the instrument as an efficient tool for nursing practice.

Albumin purification from human placenta

Albumin is the human protein used mainly for therapeutic purposes. Besides the traditionally used plasma, blood from placenta is an alternative source for albumin purification. We describe here an industrial process for purification of albumin from human placenta. The proposed albumin-purification process, for 50 kg of placentas, comprises: (i) extraction of haemolysed blood with saline and solid/liquid separation by basket centrifugation; (ii) selective precipitation of haemoglobin by ethanol/chloroform and precipitate removal by filtration in a press filter; (iii) concentration/diafiltration of the filtrate in a 30 kDa cross-flow ultrafiltration (CFUF) membrane; (iv) thermo-coagulation at 70 degrees C with sodium octanoate/EDTA; (v) treatment with activated charcoal at pH 3; (vi) concentration/diafiltration of the filtrate in a 30 kDa CFUF membrane; (vii) anion-exchange chromatography Q-Sepharose; (viii) hydrophobic-interaction chromatography with phenyl-Sepharose; and (ix) conditioning and pasteurization. The process yields an average of 4.5 g of albumin/kg of placenta with a purity of 97.1% and A(403) of 0.05 (1% protein). The final product passes pyrogen and toxicity tests in vivo and it does not contain polymers or aggregates, even after the accelerated stability test, as judged by gel filtration, as required by the Brazilian Pharmacopoeia.

Efficacy of the nocturnal bite plate in the control of bruxism for 3 to 5 year old children

Bruxism occurs in nearly 60% of children between 3 and 5 years, with important repercussions to the different components of the stomatognathic system. Nevertheless, there is little information in the literature about this topic. The aim of this study was to compare two groups of children with bruxism. One group was not submitted to treatment, serving as a control. To the other group, nocturnal bite plate was made. Cast models were made for both groups, to evaluate the progression of wear facets, during 8 months. The results are as follows: The 4 children of the control group displayed increased wear facets during the study period. On the other hand, of the 5 children that used nocturnal bite plate, showed no increase of wear facets, even after the removal of the device. From this study, we can conclude that the use of nocturnal bite plate is efficient against bruxism in 3- to 5-year-old children.

[The effect of sugar on the process of cicatrization of infected surgical incisions]

This is an experimental research based on microbiological analysis. Our aim was to evaluate the influence of sugar on the healing process of infected surgical wounds in 25 patients. On the dehiscences, there have been identified gram positive and gram negative bacteria, and fungi as well. Every patient was administered systemic antibiotics and had the wounds treated locally with crystal sugar three times a day. Statistics showed, by Person's correlation, that sugar did not influence on the healing process of infected surgical wounds in undernourished, overweight and elderly individuals.

Crystallization and preliminary X-ray diffraction studies of human catalase

The enzyme catalase (H(2)O(2)-H(2)O(2) oxidoredutase; E.C. 11.1.6) was purified from haemolysate of human placenta and crystallized using the vapour-diffusion technique. Synchrotron-radiation diffraction data have been collected to 1.76 A resolution. The enzyme crystallized in the space group P2(1)2(1)2(1), with unit-cell dimensions a = 83.6, b = 139.4, c = 227.5 A. A molecular-replacement solution of the structure has been obtained using beef liver catalase (PDB code 4blc) as a search model.

Oxidative stress induces activation of a cytosolic protein responsible for control of iron uptake

A cytosolic protein, named iron-responsive element-binding protein (IRE-BP), is sensitive to cellular iron concentration. At low cytosolic iron level, IRE-BP is activated and binds to stem-loop untranslated regions (IRE regions) of transferrin and ferritin mRNAs, activating and inhibiting their translations, respectively. This concerted mechanism permits a fine control of iron homeostasis in the cell. The activity of IRE-BP can be measured by its binding to IRE regions, using a protein band-shift electrophoretic assay. Damage to cells by oxidative stress is known to be mediated by iron. We observed that IRE-BP is rapidly activated by exposure of V79 Chinese hamster ovary cells to H2O2. However, if cell extracts are exposed to H2O2 IRE-BP activation is not observed. Therefore, the activation is not a direct consequence of the H2O2 attack to IRE-BP. The in vivo IRE-BP-activation by H2O2 is not prevented by hydroxyl radical scavengers or by the iron chelator 1,10-phenanthroline, indicating that Fenton reaction is not involved in the process. In fact, simultaneous exposure of cells to H2O2 and 1,10-phenanthroline produces an even stronger activation than exposure to H2O2 alone. The interpretation of the mechanism of IRE-BP activation by oxidative stress is hampered by the fact that the mechanism of IRE-BP modulation by cytosolic iron has not been established. It has been recently shown that the iron-sulfur cluster in IRE-BP must be completely disassembled in order for activation to occur and that this is triggered by low iron in the cell. It is likely that IRE-BP senses Fe(II) and that its oxidation to Fe(III) by H2O2 or chelation by 1,10-phenanthroline set up a program for increasing iron uptake. The physiological consequences of this activation still has to be assessed.

[Teacher-student communication across the Tizadora pedagogical problem]

Report of experience in the use of a social-cultural approach during the development of a work done by graduate students of Ribeiräo Preto School of Nursing-USP. As a form of reference for the didactic strategy, it was used the scheme of arch proposed by Charles Maguerez and presented by BORDENAVE, in an attempt to systematize the communication teacher-student talking about "Aspects related to the Undergraduate Teaching Problems".

Cellular DNA damage by hydrogen peroxide is attenuated by hypotonicity

Chinese hamster fibroblasts (line V79) withstand well exposure for 30 min to hypotonic medium, corresponding to 25% physiological phosphate-buffered saline (PBS). Under these conditions, the cells become resistant to two effects of H2O2: DNA damage and inhibition of cell clone formation. The normal sensitivity to the DNA-damaging action of H2O2 is restored if, after exposure to hypotonic PBS, the cells are incubated in isotonic cell-culture medium. However, restoration of sensitivity is not observed on incubation in isotonic PBS. The normal sensitivity to H2O2 is also restored if one of the following reducing agents is added to hypotonic PBS: ascorbate, NADH and NADPH, in this order of decreasing efficiency. The recovery of sensitivity to H2O2 by ascorbate is completely inhibited by 1,10-phenanthroline, indicating that ascorbate is mediating the reduction of Fe(III). The decrease in the sensitivity to the DNA-damaging action of H2O2 is not a peculiarity of hypotonic PBS, since it appears to be caused by hypo-osmolarity in general: it is also observed in culture medium of 25% the isotonic concentration, and in 0.07 M sucrose. One explanation for this phenomenon is that hypotonic stress leads to a depletion of reducing species, in particular ascorbate. Under these conditions Fe(II) tends to be oxidized to Fe(III) and the Fenton chemistry is mitigated. However, other possibilities are that hypotonicity brings about structural modifications in the chromatin, rendering it less accessible to H2O2, or that it attenuates the Ca(2+)-activation of endonuclease, induced by oxidative stress.

Oxidative stress by menadione affects cellular copper and iron homeostasis

Menadione produces DNA strand breaks (DNA sb) in cultured Chinese hamster fibroblasts which are, to a great extent, mediated by OH radical. A reasonable hypothesis is that H2O2, a product of menadione metabolism, reacts with nuclear iron and produces OH radical in situ. Consistent with that, 1,10-phenanthroline (PHEN) prevents menadione-induced DNA sb at low (< 200 microM) concentrations of the chelator. However, at higher PHEN concentrations, the effect is reversed and an enhancement of DNA sb is observed. The PHEN-induced enhancement of DNA sb becomes more evident at high (> 60 microM) menadione concentrations and is strongly prevented by neocuproine (NEO), an efficient copper chelator. However, NEO offers only a slight protection against DNA sb caused by menadione alone. The results are consistent with the following events: (i) the products of menadione metabolism causes copper ion release from some cellular compartment; (ii) in the presence of PHEN, a Cu(PHEN)2 complex is formed; (iii) the Cu(PHEN)2 complex is known to be very clastogenic, inducing DNA damage in a reducing environment. Evidence is also presented that menadione metabolism causes an increase in intracellular chelatable iron: in the presence of a constant 2,2'-dipyridyl concentration, the DNA sb produced by increasing concentrations of menadione become progressively less susceptible to inhibition by the chelator. Therefore the DNA damage originated from menadione metabolism seems to be caused by two conjugated and synergistic events, viz., the production of reactive oxygen species and the release of copper and iron from a cellular storage site into a 'free' form pool, capable of catalyzing DNA damaging reactions.

Menadione-resistant Chinese hamster cell variants are cross-resistant to hydrogen peroxide and exhibit stable chromosomal and biochemical alterations

We have investigated the antioxidant properties of V79 Chinese hamster cells rendered resistant to menadione by chronic exposure to increasing concentrations of this quinone. MD1, a clone of resistant cells, was compared to the parental M8 cells; the former showed increased activity of catalase (3 fold), glutathione peroxidase (1.6 fold) and DT-diaphorase (2.6 fold), as well as an increase in glutathione (3.2 fold). Although one of the products of menadione metabolism is superoxide anion, no changes in total superoxide dismutase activity was observed in MD1 cells. MD1 menadione resistant cells were also resistant to killing by hydrogen peroxide and contained tandem duplication of chromosome 6. A similar duplication of chromosome 6 was seen in several independently derived menadione resistant clones and therefore seems closed linked to the establishment of the resistance. Upon removal of menadione from the medium, some of these properties of MD1 cells, viz., resistance to menadione, elevated glutathione levels, and glutathione peroxidase activity, were lost and the cells resembled M8 cells. However, resistance to H2O2, elevated catalase activity and the duplicated chromosome remained stable for more than 40 cell passages in the absence of menadione. The increase in catalase activity was correlated with an increase in catalase mRNA content and a 50% amplification of catalase gene, as determined, respectively, by Northern and Southern blot analysis. The role of the chromosome 6 duplication in resistance to oxidative stress remains to be established. It is not responsible directly for elevated catalase levels since the catalase gene is on chromosome 3.

Role of antioxidants in protecting cellular DNA from damage by oxidative stress

We have previously derived 2 V79 clones resistant to menadione (Md1 cells) and cadmium (Cd1 cells), respectively. They both were shown to be cross-resistant to hydrogen peroxide. There was a modification in the antioxidant repertoire in these cells as compared to the parental cells. Md1 presented an increase in catalase and glutathione peroxidase activities whereas Cd1 cells exhibited an increase in metallothionein and glutathione contents. The susceptibility of the DNA of these cells to the damaging effect of H2O2 was tested using the DNA precipitation assay. Both Md1 and Cd1 DNAs were more resistant to the peroxide action. In the case of Md1 cells it seems clear that the extra resistance is provided by the increase in the two H2O2 scavenger enzymes, catalase and glutathione peroxidase. In the case of Cd1 cells the activities of these enzymes as well as of superoxide dismutases (Cu/Zn and Mn) are unaltered as compared to the parental cells. The facts that parental cells exposed to 100 microM Zn2+ in the medium exhibit an increase in metallothionein but not in glutathione and that these cells become more resistant to the DNA-damaging effect of H2O2 suggest that this protein might play a protective role in vivo against the OH radical attack on DNA.

DNA damage and lethal effects of hydrogen peroxide and menadione in Chinese hamster cells: distinct mechanisms are involved

Menadione (Md)-resistant variants of V79 Chinese hamster cells were derived by culturing cells in progressively higher concentrations of this drug. Along with Md resistance these cells acquired cross-resistance to H2O2, which was retained when cells were cultured back in the absence of Md for 18 cell passages. This indicates that some stable alteration is responsible for the modification and may suggest that the toxicity of Md is mediated by oxygen activation. In agreement with the latter a 2.8-fold increase in catalase activity and a 1.5-fold increase in glutathione content were observed in Md-resistant cells as compared to parental cells, whereas superoxide dismutase and glutathione peroxidase remained unaltered. The use of inhibitors of Fenton reaction, inhibitors of enzymatic and nonenzymatic lipid peroxidation and OH radical scavengers, indicated that both DNA damage and cytotoxic effects of H2O2 and Md are mediated by OH radical, without intervention of lipid peroxides. However whereas the catalysis by iron was required for toxicity of extracellular H2O2, it was not involved in Md-induced toxicity. Possible explanations for this difference have been considered, one of them assuming that an excess of the semiquinone form of Md in the cell might replace iron II as a H2O2 reductant, producing OH radical by an organic Fenton reaction.

Iron-mediated induction of sister-chromatid exchanges by hydrogen peroxide and superoxide anion

When Chinese hamster fibroblasts were exposed to hydrogen peroxide or to a system consisting of xanthine oxidase and hypoxanthine, which generates superoxide anion plus hydrogen peroxide, sister-chromatid exchanges (SCEs) were formed in a dose-dependent manner. When the iron-complexing agent o-phenanthroline was present in the medium, however, the production of these SCEs was completely inhibited. This fact indicates that the Fenton reaction: Fe2+ + H2O2----OH0 + OH- + Fe3+ is responsible for the production of SCEs. When O2- and H2O2 were generated inside the cell by incubation with menadione, the production of SCE was prevented by co-incubation with copper diisopropylsalicylate, a superoxide dismutase mimetic agent. The most likely role of O2- is as a reducing agent of Fe3+: O2- + Fe3+----Fe2+ + O2, so that the sum of this and the Fenton reaction, i.e., the iron-catalyzed Haber-Weiss reaction, provides an explanation for the active oxygen species-induced SCE: H2O2 + O2(-)----OH- + OH0 + O2. According to this view, the OH radical thus produced is the agent which ultimately causes SCE. These results are discussed in comparison with other mechanisms previously proposed for induction of SCE by active oxygen species.

Effect of insulin on the size of skeletal muscle fibers of fetal rhesus monkey

Increased body weight of insulin-treated fetuses is largely attributed to increased muscle mass. Skeletal muscle from fetal rhesus monkeys was analyzed for differences in the sizes of muscle fibers from monkeys treated in utero with high or low doses of insulin and compared to control (non-insulin-treated) animals. The results indicate no significant difference among the various groups studied and suggest that hyperplasia, not hypertrophy, of skeletal muscle fibers is responsible for the observed increase in muscle mass.