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Biomedical subjects

S Pereira

Publications and source records attributed to S Pereira.

At least 19 recordsLinked to original sources
PubMed2005

Repercussions of castration and vasectomy on the ductal system of the rat ventral prostate.

Diseases, such as cancer and benign prostatic hyperplasia, are related to disruption of the mechanism regulating the balance between cell proliferation and apoptosis in prostatic cells. Since castration and vasectomy might alter that balance, this study evaluates the cell proliferation, apoptosis and height of the secretory epithelium of the ventral-prostate ductal system post-castration and vasectomy. Immunohistochemical (PCNA and Ki67), cytochemical (Fuelgen reaction) and morphometric investigation have been carried out. Cell proliferation indices decreased significantly in both regions of the ventral-prostate ductal system after castration compared to the sham-operated group. The apoptotic index increased significantly after 48 h, declining 7 days post-castration. The cell proliferation indices did not differ after 48 h significantly; however, they increased 7 days post-vasectomy in both regions. The apoptotic index did not differ significantly in either time post-vasectomy. Castration caused an imbalance in favor of apoptosis, whereas vasectomy caused an imbalance in favor of cell proliferation.

Animals↗
PubMed2005

Organ-specific distribution and subcellular localisation of ascorbate peroxidase isoenzymes in potato (Solanum tuberosum L.) plants.

Ascorbate peroxidase (EC 1.11.1.11), a heme-containing homodimeric protein, is a hydrogen peroxide-scavenging enzyme, playing an important role in plants in order to protect them from oxidative stress, thus adverting cellular damage. Several ascorbate peroxidase isoenzymes have been reported but the understanding of their physiological role still depends on a better knowledge of their precise localisation within plant organs. Immunocytochemistry techniques were performed in order to elucidate the peroxisomal and cytosolic ascorbate peroxidase distribution within tissues of leaves and sprouts of potato plants. The peroxisomal isoenzyme was found to have a broad distribution in sprouts, but a differential one in leaves, being restricted to the spongy parenchyma. This differential expression may be associated to the mesophyll asymmetry and the diverse physiological processes that occur in it. The cytosolic isoenzyme was not detected in leaves under the used conditions, probably because it is present in low amounts in these tissues. The results obtained in sprouts were at least curious: cytosolic ascorbate was found to be adjacent to the amyloplasts. Given these results, it is possible to state that apart from their similarity, these two isoenzymes reside in different organelles and seem to take part in different physiological processes as suggested by their organ- and tissue-specific distribution.

Ascorbate Peroxidases↗
PubMed2005

Crohn's disease: increased mortality 10 years after diagnosis in a Europe-wide population based cohort.

BACKGROUND: No previous correlation between phenotype at diagnosis of Crohn's disease (CD) and mortality has been performed. We assessed the predictive value of phenotype at diagnosis on overall and disease related mortality in a European cohort of CD patients. METHODS: Overall and disease related mortality were recorded 10 years after diagnosis in a prospectively assembled, uniformly diagnosed European population based inception cohort of 380 CD patients diagnosed between 1991 and 1993. Standardised mortality ratios (SMRs) were calculated for geographic and phenotypic subgroups at diagnosis. RESULTS: Thirty seven deaths were observed in the entire cohort whereas 21.5 deaths were expected (SMR 1.85 (95% CI 1.30-2.55)). Mortality risk was significantly increased in both females (SMR 1.93 (95% CI 1.10-3.14)) and males (SMR 1.79 (95% CI 1.11-2.73)). Patients from northern European centres had a significant overall increased mortality risk (SMR 2.04 (95% CI 1.32-3.01)) whereas a tendency towards increased overall mortality risk was also observed in the south (SMR 1.55 (95% CI 0.80-2.70)). Mortality risk was increased in patients with colonic disease location and with inflammatory disease behaviour at diagnosis. Mortality risk was also increased in the age group above 40 years at diagnosis for both total and CD related causes. Excess mortality was mainly due to gastrointestinal causes that were related to CD. CONCLUSIONS: This European multinational population based study revealed an increased overall mortality risk in CD patients 10 years after diagnosis, and age above 40 years at diagnosis was found to be the sole factor associated with increased mortality risk.

Adolescent↗
PubMed2005

Analysis of the dinucleotide repeat polymorphism in the epidermal growth factor receptor (EGFR) gene in head and neck cancer patients.

BACKGROUND: Epidermal growth factor receptor (EGFR) overexpression is associated with poor prognosis in head and neck cancer. The first intron of EGFR gene is polymorphic (9-23 CA repeats) and transcription declines when the number of repeats increases. PATIENTS AND METHODS: EGFR polymorphism (fluorescent genotyping) and expression (ligand-binding assay) were analyzed in tumors and normal tissues from 112 patients (100 men, 12 women; mean age 60 years). RESULTS: The number of CA repeats varied from 15 to 22. Allelic distribution was trimodal (predominance of 16, 20 and 18 CA repeats). EGFR concentrations were significantly higher (P=0.02) in homozygous tumors as compared with heterozygous. Considering homozygous tumors, or classifying genotypes as short/long/intermediary (two alleles <17 versus two alleles > or =17 versus others), no relationship was observed between tumoral EGFR genotype and expression. In the 76 tumors exhibiting at least one 16-CA allele, the length of the remaining allele was inversely correlated to EGFR expression (P=0.047). Tumoral EGFR expression, performance status (WHO criteria) and node involvement were independent predictors of specific survival (P <0.01). Tumoral or normal tissue EGFR genotype did not influence survival. CONCLUSIONS: Intron 1 EGFR polymorphism may be implicated in the regulation of EGFR expression in head and neck tumors.

Adult↗
PubMed2003

PIP2 binding residues of Kir2.1 are common targets of mutations causing Andersen syndrome.

BACKGROUND: Mutations in KCNJ2, the gene encoding the inward-rectifying K+ channel Kir2.1, cause the cardiac, skeletal muscle, and developmental phenotypes of Andersen-Tawil syndrome (ATS; also known as Andersen syndrome). Although pathogenic mechanisms have been proposed for select mutations, a common mechanism has not been identified. METHODS: Seventeen probands presenting with symptoms characteristic of ATS were evaluated clinically and screened for mutations in KCNJ2. The results of mutation analysis were combined with those from previously studied subjects to assess the frequency with which KCNJ2 mutations cause ATS. RESULTS: Mutations in KCNJ2 were discovered in nine probands. These included six novel mutations (D71N, T75R, G146D, R189I, G300D, and R312C) as well as previously reported mutations R67W and R218W. Six probands possessed mutations of residues implicated in binding membrane-associated phosphatidylinositol 4,5-bisphosphate (PIP2). In total, mutations in PIP(2)-related residues accounted for disease in 18 of 29 (62%) reported KCNJ2 -based probands with ATS. Also reported is that mutation R67W causes the full clinical triad in two unrelated males. CONCLUSIONS: The novel mutations corresponding to residues involved in Kir2.1 channel-PIP2 interactions presented here as well as the overall frequency of mutations occurring in these residues indicate that defects in PIP2 binding constitute a major pathogenic mechanism of ATS. Furthermore, screening KCNJ2 in patients with the complex phenotypes of ATS was found to be invaluable in establishing or confirming a disease diagnosis as mutations in this gene can be identified in the majority of patients.

Abnormalities, Multiple↗
PubMed2003

Neovascularisation is a prognostic factor of early recurrence in T1/G2 urothelial bladder tumours.

BACKGROUND: Of patients with superficial bladder cancer, a group are still at risk of disease recurrence, progression and death from their cancer after curative treatment. Angiogenesis is a crucial pathogenic mechanism for this type of urothelial cell carcinoma (UCC), and is a potential therapeutic target. However, the selection of the appropriate patients remains a dilemma. PATIENTS AND METHODS: Vascular endothelial growth factor (VEGF) expression and the presence of angiogenesis and occurrence of CD31, CD34, endoglin and factor VIII immunoexpression, were evaluated in 66 superficial papillary UCCs of the bladder and were correlated with classical histopathological factors and disease outcome. RESULTS: VEGF immunoreactivity was observed in 100% of cases, and more intensely in the luminal surface. The presence of microvessel clusters independently of a fibrovascular core was observed in 22.7% of cases. Of these, the T1/G2 subgroup had an independent and significantly lower recurrence-free survival (P = 0.0002). CONCLUSIONS: These results indicate that the presence of angiogenesis in tumour urothelium is a potential prognostic factor in superficial UCC, particularly in T1/G2 tumours, and may be used to select patients for anti-angiogenic treatments.

Antigens, CD↗
PubMed2003

The role of adherence in tuberculosis HIV-positive patients treated in ambulatory regimen.

Adherence to antituberculosis treatment, a major determinant of outcome, is of special concern in human immunodeficiency virus (HIV)-positive patients. However, tuberculosis death in HIV-positive patients remains higher than in HIV-negative patients, regardless of adherence. To assess determinants for an unfavourable tuberculosis outcome (defined as no cure or death), and determinants for nonadherence to antituberculosis treatment, 70 HIV-positive patients with tuberculosis referred to an outpatient centre were studied. Patient outcome was compared according to HIV risk factors, other opportunistic diseases, antiretroviral drugs use, current i.v. drugs use, a methadone programme participation, tuberculosis features, treatment characteristics and adherence. Adherent and non-adherent patient characteristics were also compared. An unfavourable outcome occurred in 22.9% of patients and 32.9% were nonadherent with therapy. Nonadherence was the only independent determinant for an unfavourable outcome. Adherence was independently associated with current i.v. drug use, treatment complications and use of methadone. This study confirms that human immunodeficiency virus-infected patients, treated as outpatients, have high rates of nonadherence and that adherence is the strongest determinant for tuberculosis outcome. Independently of the current use of drugs, a methadone programme improves adherence to treatment.

Adult↗
PubMed2001

Comparison of virologic, immunologic, and clinical response to five different initial protease inhibitor-containing and nevirapine-containing regimens.

CONTEXT: The effectiveness of different protease inhibitors (PIs) and non-nucleoside reverse transcriptase inhibitors outside the setting of clinical trials has not been well described. OBJECTIVES: To compare five different PI-and nevirapine (NVP)-containing regimens on virologic, immunologic, and clinical outcomes and treatment discontinuation. DESIGN AND SETTING: Observational cohort study based on an HIV clinic in London. PATIENTS: A total of 690 patients who received either saquinavir hard gel (SQV HG) (n = 183), indinavir (IDV) (n = 189), nelfinavir (NFV) (n = 109), ritonavir (RTV) (n = 42), ritonavir with saquinavir hard gel (RTV/SQV HG) (n = 45), or NVP (n = 122) as part of an initial PI-or NVP-containing treatment regimen between November 1994 and December 1998. A total of 351 (51%) patients had prior exposure to nucleoside reverse transcriptase inhibitors (NRTIs). MAIN OUTCOME MEASURES: The main outcome measures were virologic undetectability, subsequent virologic rebound, CD4 cell count rise, development of AIDS, and treatment discontinuation. All analyses were stratified for year of initiation of the PI-or NVP-containing regimen. RESULTS: Overall, 63% of patients attained an undetectable viral load (VL) within 6 months of starting their PI or NVP regimen. The adjusted relative hazard (95% confidence interval [CI]) for an undetectable VL relative to SQV HG was (in rank order): 2.77 (CI: 1.84-4.17) for NFV, 2.54 (CI: 1.81-3.57) for IDV, 2.43 (CI: 1.52-3.87) for RTV, 2.08 (CI: 1.28-3.37) for RTV/SQV HG, and 1.96 (CI: 1.35-2.85) for NVP. Forty-nine percent of patients experienced VL rebound within 12 months of initial attainment of undetectability, but relative to SQV HG, this did not differ significantly across the different PI and NVP regimens. The CD4 cell count response and rate of AIDS events were also similar across the different regimens. No independent predictors of VL undetectability were identified, but prior NRTI exposure was associated with VL rebound, and a lower baseline VL and CD4 cell count were associated with a reduced CD4 count response. The frequency (95% CI) of treatment discontinuation differed across the regimens; at 6 months, it was lowest for NFV (18% [CI: 13%-24%]), IDV (25% [CI: 22%-29%]), and NVP (28% [CI: 22%-34%]) and highest for RTV (41% [CI: 31%-52%]) and SQV HG (52% [CI: 48%-57%]). CONCLUSIONS: Although PI- and NVP-containing regimens were similar in their CD4 cell count response and rates of subsequent VL rebound, differences were observed in time to VL undetectability and discontinuation rates relative to SQV HG. SQV HG was consistently inferior to the other PIs and NVP. The use of NFV and IDV was associated with the highest rates of undetectability, and together with NVP, the lowest rates of discontinuation.

Adult↗
PubMed2001

Resting murine neutrophils express functional alpha 4 integrins that signal through Src family kinases.

There is mounting evidence that alpha(4) (CD49d) integrins are involved in neutrophil recruitment and function during inflammatory responses. We report that all resting murine neutrophils derived from bone marrow or peripheral blood express easily detectable levels of alpha(4) integrins on their surface. These alpha(4) integrins were functional, as demonstrated by stimulation of respiratory burst when neutrophils adhered to surfaces coated with the murine vascular cell adhesion molecule-1 (mVCAM-1). Adhesion occurred via alpha(4) integrins, as preincubation of neutrophils with an anti-alpha(4)-specific Ab inhibited attachment to mVCAM-1. Direct cross-linking of the alpha(4) integrin subunit by surface-bound mAbs also elicited superoxide release and release of the secondary granule marker, lactoferrin. The functional responses that occurred downstream of alpha(4) integrin cross-linking required signaling by Src family kinases. Neutrophils derived from hck(-/-)fgr(-/-)lyn(-/-) triple-knockout or hck(-/-)fgr(-/-) double-knockout mice failed to undergo respiratory burst when plated on mVCAM-1. Triple mutant neutrophils were also defective in release of both superoxide and lactoferrin when plated on surfaces coated with mAbs directed against alpha(4). Correlated with impaired alpha(4)-induced functional responses, triple-mutant neutrophils also failed to spread and tightly adhere to anti-alpha(4) mAb-coated surfaces. This is the first direct evidence that functional alpha(4) integrins are expressed by murine PMNs, and that these surface molecules can mediate cellular responses such as tight adhesion, spreading, sustained respiratory burst, and specific granule release in vitro. Moreover the alpha(4) integrins, like all other integrins tested, use the Src family kinases to transduce intracellular signals.

Animals↗
PubMed2001

Isolation of the melanoma-associated antigen p23 using antibody phage display.

The general responsiveness of human melanoma to immunotherapy has been well established, but active immunotherapy of melanoma has been hampered by insufficient information on the immunogenicity of melanoma-associated Ags in patients. In this study, we isolated a recombinant phage-Fab clone (A10-5) from a phage-Fab library derived from the B cells of a melanoma patient in remission after immunotherapy. Purified A10-5 Fab bound at high levels to cultured melanoma cell lines and to tissue sections of metastatic and vertical growth phase primary melanoma, but not to radial growth phase primary melanoma, nevi, or normal skin. A10-5 Fab bound to both the surface and the cytoplasm of cultured melanoma cells, but only to the cytoplasm of cultured fibroblasts. Western blot analysis revealed A10-5 Fab reactivity with a 33- and a 23-kDa glycoprotein under nonreducing conditions, and with a 23-kDa protein only under reducing conditions. A cDNA with an open reading frame predicted to encode a 23-kDa protein was cloned by screening a melanoma cell cDNA library with A10-5 Fab. This protein (p23) is the human homologue of the murine tumor transplantation Ag P198 that interacts with the cytoplasmic domain of ErbB-3 expressed by melanoma cells. Thus, the Ab phage display method has identified a novel, stage-specific melanoma-associated Ag that may have therapeutic and diagnostic value.

Animals↗
PubMed2001

Quantitation of cyclosporin A in whole blood by liquid chromatography/stable isotope dilution electrospray ionization mass spectrometry.

Therapy with cyclosporin A (CsA) for immunosuppression after organ transplantation requires monitoring of its levels in blood owing to the narrow therapeutic index of the drug and to the high inter-individual variability of the drug absorption and metabolism. We describe the preparation of CsA labelled with stable isotopes ((13)C and (2)H) with an isotopic enrichment of about 99% using labelled glucose and its use as internal standard for quantification of CsA blood levels by isotope dilution/electrospray ionization mass spectrometry. The method was found to be linear in the tested range (1-1000 ng) with and without the matrix. The accuracy of the bracketting calibration curves prepared using 100 ng ml(-1) labelled CsA was within +/-1.7% (bias). The results confirmed the usefulness of the procedure as a reference method for the external quality assessment of the field methods for the evaluation of CsA blood concentration, the imprecision (relative standard deviation) and accuracy (bias) being <2%.

Chromatography, High Pressure Liquid↗
PubMed2001

Appropriateness of emergency department visits in a Portuguese university hospital.

STUDY OBJECTIVE: There are no studies in Portugal supporting a common claim that most emergency department visits are inappropriate. The aim of this study was to determine the prevalence of and to evaluate factors associated with an appropriate ED visit in a major public hospital. METHODS: A cross-sectional prospective study was performed at a public university hospital ED. Data for demographic variables, duration of complaint, transfer from other medical sources, and previous medical care for the same complaints were collected by interviewing all patients who arrived at the ED within a consecutive period of at least 24 hours. Data for diagnostic tests, treatment performed, and final patient destination were collected by triage records review. An appropriate ED visit was defined by explicit criteria: interhospital transfer, patient death at the ED, hospitalization, and diagnostic tests or treatments performed. RESULTS: The study included 5,818 adult patients. The prevalence of an appropriate ED visit, by use of our criteria, was 68.7%. Sex was an effect modifier. According to this study, determinants of an appropriate visit for men and women were age 60 years or older and complaints of 24 hours or less and in women but not in men, retired from work and with arrival between midnight and 8 AM. CONCLUSIONS: In a university hospital in Oporto, the majority of ED visits were appropriate according to explicit criteria. Some variables may be associated with appropriateness of ED visits. A duration of the complaint 24 hours or less along with an arrival between midnight and 8 AM in women and age 60 years or older in men were the most important determinants.

Adult↗
PubMed2001

Laparoscopic cryoablation of a metastatic carcinoid tumor.

Carcinoid tumors are rare, slow-growing neuroendocrine neoplasms that can cause a carcinoid syndrome. The majority of carcinoid syndromes are the result of multiple hepatic metastases and are usually unresectable. Medical therapy has not proven effective and often causes intolerable side effects. Cryoablation has emerged as a promising treatment for various hepatic lesions when resection is not an option and medical therapy has been exhausted. With the addition of laparoscopy, surgeons now possess a new technique to treat primary and various secondary liver lesions. We report for the first time laparoscopic cryoablation for the treatment of a carcinoid metastatic to the liver.

Aged↗
PubMed2001

Identification of clinical staphylococcal isolates from humans by internal transcribed spacer PCR.

The emergence of coagulase-negative staphylococci not only as human pathogens but also as reservoirs of antibiotic resistance determinants requires the deployment and development of methods for their rapid and reliable identification. Internal transcribed spacer-PCR (ITS-PCR) was used to identify a collection of 617 clinical staphylococcal isolates. The amplicons were resolved in high-resolution agarose gels and visually compared with the patterns obtained for the control strains of 29 staphylococcal species. Of the 617 isolates studied, 592 (95.95%) were identified by ITS-PCR and included 11 species: 302 isolates of Staphylococcus epidermidis, 157 of S. haemolyticus, 79 of S. aureus, 21 of S. hominis, 14 of S. saprophyticus, 8 of S. warneri, 6 of S. simulans, 2 of S. lugdunensis, and 1 each of S. caprae, S. carnosus, and S. cohnii. All species analyzed had unique ITS-PCR patterns, although some were very similar, namely, the group S. saprophyticus, S. cohnii, S. gallinarum, S. xylosus, S. lentus, S. equorum, and S. chromogenes, the pair S. schleiferi and S. vitulus, and the pair S. piscifermentans and S. carnosus. Four species, S. aureus, S. caprae, S. haemolyticus, and S. lugdunensis, showed polymorphisms on their ITS-PCR patterns. ITS-PCR proved to be a valuable alternative for the identification of staphylococci, offering, within the same response time and at lower cost, higher reliability than the currently available commercial systems.

DNA, Bacterial↗
PubMed2001

Transesophageal echocardiography in the assessment of patients presenting with ischemic cerebral events without previous evidence of a cardiac source of emboli.

UNLABELLED: Transesophageal echocardiography (TEE) is accepted as a valuable tool in the evaluation of ischemic stroke patients, particularly in the young and in cases of unknown cause. However, the real clinical impact of additional TEE data remains to be defined. PURPOSE: The aim of this study was to present our experience with TEE in ischemic stroke patients without previous evidence of a cardiac source of emboli. METHODS: From March 1991 to June 2000 we studied 172 patients (80 males, 92 females, mean age 43 +/- 12 years presenting with a transient ischemic attack or a recent cerebral infarction who had no previous evidence by clinical assessment, electrocardiogram and transthoracic echocardiography of a cardiac of emboli source. The population was divided into two groups: Group A--age < or = 45 years, n = 101 (43 males, 58 females, mean age 34 +/- 7 years) and Group B--age > 45 years, n = 71 (36 males, 35 females, mean age 54 +/- 7 years). Information was gathered from clinical records. In every case TEE included Doppler color flow imaging and multiple contrast injections (agitated saline) with and without Valsalva maneuver. RESULTS: A potential cardiac of emboli source was found in 29% of the patients, with a higher prevalence in the older group (group A--25%, Group B--35%, ns). Atrial septal abnormalities accounted for most of the detected findings (23 patent foramen ovale, 17 atrial septal aneurysms and two atrial septal defects, representing altogether 71% of the findings). The other detected anomalies were distributed as follows: aortic plaques--six, mitral valve prolapse--five vegetations--four, thrombus in left atrial appendage--two. Only six patients (3.5%) had abnormalities which in themselves determined a specific approach, which were found mostly in the older group (Group A--two vegetations; Group B--two vegetations, two thrombi). CONCLUSIONS: TEE identified additional findings with possible embolic potential in a considerable number of cases, the majority of which were of a debatable cause-effect relation. A higher diagnostic yield and clinical relevance was found in older patients, which argues against age being used as a selective criterion for it. Our experience suggests that routine TEE in this setting is of questionable value and has little impact on clinical management, for which reason TEE referral should be decided on an individual patient basis.

Brain Ischemia↗
PubMed2000

Identification of sulfonylureas in serum by electrospray mass spectrometry.

Identification of sulfonylureas in serum is important in the diagnosis of hypoglycemic crisis of unknown origin. Methods based on HPLC with UV or fluorescence detection may give false positive results. Mass spectrometry may successfully avoid this problem. The described method allows the simultaneous identification and quantification of tolbutamide, chlorpropamide, glibenclamide, and glipizide in human serum using one of the tested sulfonylureas as the internal standard. Serum purification is carried out by solid-phase extraction with ENVI-C18 cartridges and samples are analyzed by liquid chromatography-electrospray mass spectrometry. For all drugs, the limit of detection and the limit of quantification are about 2 and 10 ng/ml, respectively.

Calibration↗