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Biomedical subjects

C A Pereira

Publications and source records attributed to C A Pereira.

At least 19 recordsLinked to original sources
PubMed2005

Mouse hepatitis virus 3 binding to macrophages correlates with resistance to experimental infection.

Mouse hepatitis virus 3 (MHV3) infection of A/J and BALB/c mice has been used as a model of resistance/susceptibility. A/J mice recover from a mild disease after 4-6 days of infection and the BALB/c mice develop an acute hepatitis and die after 3-4 days of infection. In view of studying the MHV3 binding to cells or cell extracts, we performed an enzyme-linked immunosorbent assay-like virus-binding assay, preparing microplates with L929 cells, A/J or BALB/c mouse macrophages and also with proteins extracted from these cells. Higher MHV3 bindings were observed to proteins of BALB/c macrophages than to the A/J ones. The interferon-gamma (IFN-gamma) activation led to a reduction of MHV3 binding only to proteins of resistant A/J mouse macrophages. Our experiments contribute to the hypothesis that IFN-gamma activation of macrophages plays an important role against MHV3 infection by downregulating the expression of viral receptors.

Animals↗
PubMed2004

Gene expression in IFN-gamma-activated murine macrophages.

Macrophages are critical for natural immunity and play a central role in specific acquired immunity. The IFN-gamma activation of macrophages derived from A/J or BALB/c mice yielded two different patterns of antiviral state in murine hepatitis virus 3 infection, which were related to a down-regulation of the main virus receptor. Using cDNA hybridization to evaluate mRNA accumulation in the cells, we were able to identify several genes that are differently up- or down-regulated by IFN-gamma in A/J (267 and 266 genes, respectively, up- and down-regulated) or BALB/c (297 and 58 genes, respectively, up- and down-regulated) mouse macrophages. Macrophages from mice with different genetic backgrounds behave differently at the molecular level and comparison of the patterns of non-activated and IFN-gamma-activated A/J or BALB/c mouse macrophages revealed, for instance, an up-regulation and a down-regulation of genes coding for biological functions such as enzymatic reactions, nucleic acid synthesis and transport, protein synthesis, transport and metabolism, cytoskeleton arrangement and extracellular matrix, phagocytosis, resistance and susceptibility to infection and tumors, inflammation, and cell differentiation or activation. The present data are reported in order to facilitate future correlation of proteomic/transcriptomic findings as well as of results obtained from a classical approach for the understanding of biological phenomena. The possible implication of the role of some of the gene products relevant to macrophage biology can now be further scrutinized. In this respect, a down-regulation of the main murine hepatitis virus 3 receptor gene was detected only in IFN-gamma-activated macrophages of resistant mice.

Animals↗
PubMed2004

Rabies virus production in high vero cell density cultures on macroporous microcarriers.

The purpose of the study was to investigate the rabies virus multiplication in Vero cell cultures performed on porous microcarriers, MCs (cellulose-Cytopore and gelatin-Cultispher G), which provide higher available surface area compared with solid (nonporous) MCs (DEAE-Cytodex 1). In a set of experiments performed at the same MC concentration (MCs per milliliter), cell densities regularly obtained in porous MC cultures were comparable, but almost twice as high as those in solid MC cultures. In addition, 41.1 +/- 3.9-, 35.2 +/- 2-, and 19.6 +/- 5.8-fold increases in cell concentration, relative to the initial cell number, along with maximum rabies virus titers of 6.3 +/- 0.3 x 10(4), 5 +/- 0.1 x 10(4), and 4.3 +/- 0.2 x 10(4) FFD(50)/mL were observed in Cytopore, Cultispher G, and Cytodex 1 MC cultures, respectively. When higher concentrations of MCs were employed, lower performances of virus production and MC-cell occupation (cells per MC or cells per square millimeter) were observed. Cell attachment to MCs was shown to be faster for Cytopore MCs and Cytodex 1 MCs than for Cultispher G MCs. Concerning the kinetics of cell multiplication on MCs, exponential cell growth, at similar specific cell growth rates, took place on Cytopore, Cultispher G, and Cytodex 1 MCs. In addition, cell densities as high as 2.1 +/- 0.2 x 10(6) cells/mL on Cytopore MCs, 1.8 +/- 0.1 x 10(6) cells/mL on Cultispher G MCs, and 1 +/- 0.3 x 10(6) cells/mL on Cytodex 1 MCs were regularly obtained in batch cultures. Optical as well as scanning and transmission electron microscopy studies carried out to analyze MC structure, MC cell occupation, and cell permissivity to virus infection demonstrated that there was uniform cell distribution in the external and internal areas of the MCs, suggesting an efficiency of virus synthesis. Our results indicate the usefulness of these supports for rabies virus antigen production, as well as possibilities for further optimization.

Animals↗
PubMed2003

Resource utilization and cost of episodes of febrile neutropenia in children with acute leukemias and lymphomas.

The resource utilization and cost of 51 episodes of febrile neutropenia in children with leukemia and lymphomas who were admitted to the Pediatric Oncology Institute (GRAAC) of the Federal University of São Paulo were analyzed. Patients aged 60 days to 21 years with confirmed diagnoses of acute myeloid leukemia, acute lymphoid leukemia, non-Hodgkin lymphoma, or Hodgkińs disease who presented axillary temperature above 38 degrees C at least once episode, or between 37.5 degrees C and 38 degrees C on three occasions during a 24-h period, neutrophil count below 500/mm(3), or between 500/mm(3)and 1,000/mm(3) but expected to fall below 500/mm(3) were included in the study. The patients' ages varied between 1 and 15.6 years, and 67% of the patients were male. The median cost per treated episode was US dollars 2,660 (2,039). Hospitalization costs accounted for 62% of the total cost of the treatment, antibacterials accounting for 23%. Episodes in patients with documented infections had a higher median direct cost than episodes in patients with fever of unknown origin (P=0.018). There was a trend for a higher median direct cost in episodes among patients with a worse prognostic factor, such as type of underlying disease, presence of documented infection, and longer duration of neutropenia. This is the first study to evaluate the economics of febrile neutropenia episodes in Brazil, and serves as a basis for resource utilization and costs incurred in the treatment of such patients in this country.

Adolescent↗
PubMed2001

Higher production of rabies virus in serum-free medium cell cultures on microcarriers.

Rabies virus suspensions were obtained from VERO cells cultivated on solid microcarriers in a bioreactor after infection with the Pasteur rabies virus strain (PV). Virus production-serum free medium (VP-SFM) or Leibovitz 15 (L15) medium supplemented or not with fetal calf serum (FCS) were used to cultivate the VERO cells, before and after virus infection. The cell growth was shown to reach higher densities (1.6 x 10(6) cellsmol(-l)), when VP-SFM supplemented with 1% of FCS was used during the cell growth phase of culture, and then replaced by VP-SFM alone for the virus multiplication phase. In the cultures performed from the beginning with VP-SFM, lower densities accompanied by an altered cell morphology and detachment from the microcarriers were always observed. In rabies virus infected cultures, kinetic studies showed that higher virus yields (10(4.7) FFD(50) per 0.05 ml) were always obtained in cultures performed initially on VP-SFM supplemented with 1% FCS and after infection on VP-SFM alone. In agreement with that, rabies virus production, as measured by the average of virus titers in harvests obtained at different times after infection were shown to be 5.5 times higher in the cell cultures using initially VP-SFM+1%FCS and, following infection, VP-SFM alone. Besides the advantages of using media with a well-controlled composition, these data indicate the usefulness of serum free media also in terms of virus productivity.

Animals↗
PubMed2001

Inhaled budesonide for adults with mild-to-moderate asthma: a randomized placebo-controlled, double-blind clinical trial.

CONTEXT: Budesonide is an inhaled corticosteroid with high topical potency and low systemic activity recommended in the treatment of chronic asthma. OBJECTIVE: This study was conducted to determine the efficacy and safety of inhaled budesonide via a breath-activated, multi-dose, dry-powder inhaler. TYPE OF STUDY: Multicenter randomized parallel-group, placebo-controlled, double-blind, clinical trial. SETTING: Multicenter study in the university units. PARTICIPANTS: Adult patients with mild-to-moderate asthma that was not controlled using bronchodilator therapy alone. PROCEDURES: Comparison of budesonide 400 microg administered twice daily via a breath-activated, multi-dose, dry-powder inhaler with placebo, in 43 adult patients (aged 15 to 78 years) with mild-to-moderate asthma (FEV1 71% of predicted normal) that was not controlled using bronchodilator therapy alone. MAIN MEASUREMENTS: Efficacy was assessed by pulmonary function tests and asthma symptom control (as perceived by the patients) and the use of rescue medication. RESULTS: Budesonide 400 microg (bid) was significantly more effective than placebo in improving morning peak expiratory flow (mean difference: 67.9 l/min; P < 0.005) and FEV1 (mean difference: 0.60 l; P < 0.005) over the 8-week treatment period. Onset of action, assessed by morning peak expiratory flow, occurred within the first two weeks of treatment. CONCLUSIONS: Budesonide via a breath-activated, multi-dose, dry-powder inhaler results in a rapid onset of asthma control, which is maintained over time and is well tolerated in adults with mild-to-moderate asthma.

Administration, Inhalation↗
PubMed2001

Arginine kinase of the flagellate protozoa Trypanosoma cruzi. Regulation of its expression and catalytic activity.

In epimastigotes of Trypanosoma cruzi, the etiological agent of Chagas' disease, arginine kinase activity increased continuously during the exponential phase of growth. A correlation between growth rate, enzyme-specific activity and enzyme protein was observed. Arginine kinase-specific activity, expressed as a function of enzyme protein, remains roughly constant up to 18 days of culture. In the whole range of the culture time mRNA levels showed minor changes indicating that the enzyme activity is post-transcriptionally regulated. Arginine kinase could be proposed as a modulator of energetic reserves under starvation stress condition.

Animals↗
PubMed2001

Prospective comparison of arm veins and greater saphenous veins as infrageniculate bypass grafts.

OBJECTIVES: to compare arm and saphenous veins for infrageniculate bypass grafting. DESIGN: prospective non-randomised study. MATERIALS: two hundred patients, of which 197 had ischaemic tissue loss or rest pain. METHODS: two hundred and eleven infrageniculate vein bypass procedures using 176 greater saphenous veins and 35 arm veins. RESULTS: the cumulative primary graft patency rate at 1-month and 2 years was 80% and 61% for saphenous vein and 89% and 42% for arm vein. The corresponding rates for secondary patency were 84.5% and 68%, and 91% and 57%, respectively. These results corresponded to a relative risk of secondary failure of 1.53 (95% CI 0.71, 3.31) for arm vein grafts. In subgroup analyses, this estimate was 0.93 and 2.1 for primary vs secondary bypasses and 0.38 and 2.06 for single-vein vs spliced-vein bypasses. Among arm veins, cephalic vein grafts performed better than basilic vein grafts. Early mortality was 14% for arm vein and 10% for saphenous vein. CONCLUSION: in the setting of infrageniculate bypass grafting, arm vein grafts are not equivalent to greater saphenous vein grafts, but contribute importantly to a policy of using autologous veins. The possibility of equivalence remains for the arm vein graft that uses a cephalic vein or is a primary procedure.

Aged↗
PubMed2001

Effects of lead and/or zinc exposure during the second stage of rapid postnatal brain growth on delta-aminolevulinate dehydratase and negative geotaxis of suckling rats.

Lead has been shown to produce cognitive and motor deficits in young rats that could be mediated, at least in part, by inhibition of the zinc-containing heme biosynthetic enzyme delta-aminolevulinate dehydratase (ALA-D). In the present study we investigated the effects of lead and/or zinc treatment during the second stage of rapid postnatal brain development on brain, kidney and blood ALA-D specific activity, as well as the negative geotaxis behavior of rats. Eight-day-old Wistar rats were injected intraperitoneally with saline, lead acetate (8 mg/kg) and/or zinc chloride (2 mg/kg) daily for five consecutive days. Twenty-four hours after treatment, ALA-D activity was determined in the absence and presence of DL-dithiothreitol (DTT). The negative geotaxis behavior was assessed in 9- to 13-day-old rats. Treatment with lead and/or zinc did not affect body, brain or kidney weights or brain- or kidney-to-body weight ratios of the animals. In spite of the absence of effect of any treatment on ALA-D specific activity in brain, kidney and blood, the reactivation index with DTT was higher in the groups treated with lead or lead + zinc than in the control group, in brain, kidney and blood (mean +/- SEM; brain: 33.33 +/- 4.34, 38.90 +/- 8.24, 13.67 +/- 3.41; kidney: 33.50 +/- 2.97, 37.60 +/- 2.67, 15.80 +/- 2.66; blood: 63.95 +/- 3.73, 56.43 +/- 5.93, 31.07 +/- 4.61, respectively, N = 9-11). The negative geotaxis response behavior was not affected by lead and/or zinc treatment. The results indicate that lead and/or zinc treatment during the second stage of rapid postnatal brain growth affected ALA-D, but zinc was not sufficient to protect the enzyme from the effects of lead in brain, kidney and blood.

Animals↗
PubMed2000

Down-regulation of Bgp1(a) viral receptor by interferon-gamma is related to the antiviral state and resistance to mouse hepatitis virus 3 infection.

Together with the evidence that the reduced virus growth and the antiviral state induced by interferon (IFN)-gamma, occurring only in macrophages from resistant animals, correlated with the decrease of MHV3 binding to macrophage membrane proteins, we show here the expression of cellular and viral genes in resistant (A/J) and susceptible (BALB/c) mouse macrophages after IFN-gamma activation/infection. The expression of interferon response gene 47 and interferon regulatory factor 1 genes takes place after IFN-gamma activation in both macrophages, indicating their activation. The expression of the biliary glycoprotein 1(a) (Bgp1(a), the main virus receptor) decreased only in IFN-gamma-activated A/J mouse macrophages, in contrast to the expression of the Bgp2 (alternative receptor), which was not influenced by IFN-gamma activation. The synthesis of both viral mRNA and virus particles was delayed only in IFN-gamma-activated A/J mouse macrophages compared with susceptible BALB/c macrophages. Besides the evidence that IFN-gamma may modulate the expression of the Bgp1(a) isoform of carcinoembryonic antigen family, these data show that IFN-gamma, which induces resistance against MHV3 infection, may be involved in the down-regulation of the main viral receptor expression, a key step forward in our understanding of the molecular basis of resistance against virus infection.

Animals↗
PubMed2000

Molecular characterization of canine parvovirus in Brazil by polymerase chain reaction assay.

Canine parvovirus (CPV) was first isolated in 1978 in the USA. Analysis of CPV isolates by monoclonal antibodies and restriction enzymes have shown that after the first emergence of CPV (CPV-2) it evolved to give rise to new antigenic types, which were designated CPV type 2a and type 2b. These new types have replaced the original CPV type 2, although the proportions of each of the new antigenic types vary in different countries. In Brazil, CPV-like infections were first observed in 1979, however, there has been no information concerning the antigenic types of CPV prevailing in South America. In this study, we designed a PCR assay to type canine parvovirus strains in fecal samples collected from symptomatic dogs during 1980 through 1986 and 1990 through 1995. Our data showed that the CPV epizootic in Brazil followed the same pattern observed in the USA of emergence of CPV-2 followed by replacement by the variants CPV-2a and 2b. The predominant strain found during 1980 was CPV-2a, which was substantially replaced by CPV-2b from 1990 to 1995.

Animals↗
PubMed2000

Trypanosoma cruzi arginine kinase characterization and cloning. A novel energetic pathway in protozoan parasites.

This work contains the first description of a guanidino kinase in a flagellar unicellular parasite. The enzyme phosphorylates L-arginine and was characterized in preparations from Trypanosoma cruzi, the ethiological agent of Chagas' disease. The activity requires ATP and a divalent cation. Under standard assay conditions (1 mM L-arginine), the presence of 5-fold higher concentrations of canavanine or histidine produced a greater than 50% enzyme inhibition. The base sequence of this enzyme revealed an open reading frame of 357 amino acids and a molecular weight of 40,201. The amino acid sequence shows all of the characteristic consensus blocks of the ATP:guanidino phosphotransferase family and a putative "actinin-type" actin-binding domain. The highest amino acid identities of the T. cruzi sequence, about 70%, were with arginine kinases from Arthropoda. Southern and chromosome blots revealed that the kinase is encoded by a single-copy gene. Moreover, Northern blot analysis showed an mRNA subpopulation of about 2.0 kilobases, and Western blotting of T. cruzi-soluble polypeptides revealed a 40-kDa band. The finding in the parasite of a phosphagen and its biosynthetic pathway, which are totally different from those in mammalian host tissues, points out this arginine kinase as a possible chemotherapy target for Chagas' disease.

Amino Acid Sequence↗
PubMed2000

Diffuse panbronchiolitis in Latin America.

Diffuse panbronchiolitis (DPB) is a unusual form of bronchiolar disease that has been reported almost exclusively in Asians. We describe DPB in a non-Asian Brazilian citizen who has never traveled outside the country. The clinical, radiographic, and histologic features of this case resemble those described in Japanese patients. The present case shows that DPB, although rare in Western countries, is not a disease restricted to Asia. It always should be considered in the differential diagnosis of nodular radiographic opacities associated with airflow limitation, especially in non-smokers with a history of chronic sinusitis.

Adult↗
PubMed2000

Evaluation of the short-form 36-item questionnaire to measure health-related quality of life in patients with idiopathic pulmonary fibrosis.

OBJECTIVE: To validate the use of the 36-item short-form questionnaire (SF-36) for measuring health-related quality of life (HRQL) in patients with idiopathic pulmonary fibrosis (IPF). DESIGN: : Observational data at a single point in time. SETTING: : A specialized outpatient respiratory clinic. PARTICIPANTS: Thirty-four patients (mean +/- SE age, 58.29 +/- 1.87 years) with IPF and no significant comorbidity. A matched control group for HRQL measurements was composed of 34 normal subjects (mean age, 58.00 +/- 1.89 years). MEASUREMENTS AND RESULTS: Dyspnea was measured by the baseline dyspnea index (BDI). Respiratory function evaluation included FVC, FEV(1), and resting arterial blood gases. IPF patients showed a mean BDI score of 5.21 +/- 0.46. The mean FVC and FEV(1) values were 62.41 +/- 2.96% and 66.41 +/- 3.33%, respectively. The mean PaO(2) was 67 +/- 2.51 mm Hg, and the mean PaCO(2) was 37 +/- 1. 05 mm Hg. Patients scored significantly worse than control subjects with respect to the SF-36 domains of physical functioning, physical role, general health perceptions, vitality, social functioning, emotional role, and mental health index. BDI scores were significantly correlated with five SF-36 components, and FVC and FEV(1) were significantly correlated with two SF-36 components. Significant negative correlations were found between arterial pH and four SF-36 domains. CONCLUSIONS: Patients with IPF have a significant impairment of HRQL in both physical and psychological functioning. Dyspnea is the most important factor influencing the quality of life in these subjects. The SF-36 questionnaire is a valid instrument to evaluate HRQL in IPF patients.

Adaptation, Psychological↗
PubMed1999

Parameters influencing human mu opioid receptor over-expression in baculovirus-infected insect cells.

The cDNA encoding the human mu opioid receptor (hMOR) was cloned in the baculovirus Autographa californica (AcMNPV) under the control of the polyhedrin promoter. We investigated the influence of different molecular constructions on receptor expression levels: the receptor was fused either to an amino- or a carboxy-terminal histidine tag (hMOR-N-His and hMOR-C-His respectively), or to the cleavable sequence signal of the baculovirus gp64 glycoprotein (gp-hMOR and gp-hMOR-C-His). Two cell lines, Spodoptera frugiperda (Sf9) and Trichoplusia ni (BTI-TN-5B1-4), in combination with three different culture media were also tested for their ability to produce maximal protein expression. Molecular constructions and culture conditions were both shown to influence substantially protein production. The best results were obtained using cells adapted to serum-free medium combined with constructions in fusion with the endogenous signal sequence of the baculovirus gp64 protein. Those conditions led to maximal expression and shortened the time required for receptor production. We also showed that an amino-terminal location of a hexahistidine tag was more detrimental to the expression level than a carboxy-terminal position.

Animals↗
PubMed1999

Biaxial mechanical/structural effects of equibiaxial strain during crosslinking of bovine pericardial xenograft materials.

We have investigated the effect of biaxial constraint during glutaraldehyde crosslinking on the equibiaxial mechanical properties of bovine pericardium. Crosslinking of cruciate samples was carried out with: (i) no applied load, (ii) an initial 25 g ( approximately 30 kPa) equibiaxial load, or (iii) an initial 200 g (approximately 250 kPa) equibiaxial load. All loading during crosslinking was done under a defined initial equibiaxial load and subsequently fixed biaxial strain. Load changes during crosslinking were monitored. Mechanical testing and constraint during crosslinking were carried out in a custom-built biaxial servo-hydraulic testing system incorporating four actuators with phase-controlled waveform synthesis, high frame-rate video dimension analysis, and computer-interfaced data acquisition. The paired biaxial stress strain responses under equibiaxial loading at 1 Hz (before and after treatment) were evaluated for changes in anisotropic extensibility by calculation of an anisotropy index. Scanning electron microscopy (SEM) was performed on freeze-fractured samples to relate collagen crimp morphology to constraint during crosslinking. Fresh tissue was markedly anisotropic with the base-to-apex direction of the pericardium being less extensible and stiffer than the circumferential direction. After unconstrained crosslinking, the extensibility in the circumferential direction, the stiffness in the base-to-apex direction, and the tissue's anisotropy were all reduced. Anisotropy was preserved in the tissue treated with an applied 25 g load; however, tissue treated with an applied 200 g load became extremely stiff and nearly isotropic. SEM micrographs correlated well with observed extensibility in that the collagen fibre morphology changed from very crimped (unconstrained crosslinking), to straight (200 g applied load). Biaxial stress-fixation may allow engineering of bioprosthetic materials for specific medical applications.

Animals↗
PubMed1999

HIV-1 long terminal repeat modulation by glucocorticoids in monocytic and lymphocytic cell lines.

Glucocorticoid gene regulation can be carried out through direct binding of glucocorticoid receptor to glucocorticoid responsive elements (GRE), regulating directly gene transcription and modulating some signaling pathways. The human immunodeficiency virus type 1 (HIV-1) expression can be activated by different immunomodulators through binding of particular nuclear factors to its long terminal repeat (LTR). In order to investigate the effect of glucocorticoids in pathways that activate HIV-1 expression, we transfected promonocyte (U937) and T lymphocyte (CEM-T4) cell lineages with a plasmid containing the chloramphenicol acetyl transferase (CAT) reporter gene under the control of the HIV-1 LTR. In U937 cells, dexamethasone (DEX) downregulates CAT expression induced by either phorbol myristate acetate (PMA), tumor necrosis factor alpha (TNFalpha) or granulocyte/macrophage-colony stimulating factor (GM-CSF). In CEM-T4 cells the CAT activity was slightly upregulated by DEX following the induction by either PMA or TNFalpha. Interestingly, in both cell lines transactivation of this reporter gene by transactivator protein (TAT) was downregulated by DEX. When the CAT gene was under control of HIV-1 enhancer isolated from its LTR background, the CAT activity induced by PMA was not affected by the presence of glucocorticoids. In all experiments, comparable data were obtained when DEX was replaced by hydrocortisone (HC). Our results show that, depending on the cell line, glucocorticoids can differently affect HIV-1 expression, probably by interfering in cellular pathways involved in virus expression. Moreover, the target of this regulation in LTR is probably not the enhancer region itself.

Cell Line↗