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Biomedical subjects

S Pereira

Publications and source records attributed to S Pereira.

At least 37 records · Page 2Linked to original sources
PubMed2000

Light propagation through birefringent, nonlinear media with deep gratings

We present a theory that includes birefringence in the description of one-dimensional photonic band-gap materials with a Kerr nonlinearity. The Bloch functions in the absence of nonlinearity completely characterize the linear problem, for deep as well as shallow gratings, and the method of multiple scales is used to include the effects of nonlinearity and finite optical pulse length. We derive two sets of equations appropriate in different frequency regimes, a set of coupled mode equations and a set of coupled nonlinear Schrodinger equations; we investigate the connections between these equations and where their regimes of validity overlap. Finally, we use our results to describe energy exchange between polarization modes in a birefringent medium.

Journal Article↗
PubMed2000

[Isolated infective endocarditis of pulmonary valve in patient with interventricular septal defect].

A case of isolated infective endocarditis of the pulmonary valve in a patient with known subpulmonary interventricular septal defect that had, as major complication pulmonary septic embolization, was reported by the authors. The disease followed an insidious course, diagnosed by the presence of vegetations in the echocardiogram, some of them larger than 1 cm. They were found in the right ventricular infundibulum and in the pulmonary valve leaflets. The isolation of Estreptococcus viridans in blood cultures has confirmed the diagnosis. In spite of appropriate antimicrobial therapy, according to the antibiogram data (with Ampicillin and Gentamicin), fever lasted for more than three weeks. This event suggested medical treatment failure and the possibility of surgery was considered. However, the endocarditis eventually healed with medical therapy alone, and this unusual course with prolonged fever was presumed to be caused by lung metastatic infection secondary to septic embolization. This complication is relatively common, but lung involvement is usually a subclinical event, not responsible for such persistent fever, as happened in the case now reported. We emphasize the rarity of this case, the unusual clinical course and the discussion concerning the therapeutic options.

Adult↗
PubMed1999

Diagnosis of fibromatosis colli by fine needle aspiration (FNA) cytology.

This study presents eight cases of fibromatosis colli accurately diagnosed by FNA cytology. Fibromatosis colli is a rare fibroblastic lesion that manifests in the sternocleidomastoid muscle during the first to second months after birth. The tumours varied in size from 1 to 3 cm and engaged the lower, middle as well as the upper part of the sternocleidomastoid muscle. The FNA cytology smears showed mostly mature fibroblasts in a background of pink granular material and fragments of striated muscle fibres with degeneration. The cytological presentation together with the typical clinical setting will allow a definitive and accurate diagnosis, avoiding surgery.

Biopsy, Needle↗
PubMed1999

Impaired arterial baroreceptor sensitivity before tilt-induced syncope.

Autonomic dysfunction seems to play a central role in the pathophysiology of neurocardiogenic syncope (NCS) but conflicting data have recently become available. We evaluated autonomic nervous system (ANS) function (heart rate variability (HRV), systolic blood pressure variability (SBPV) and baroreceptor gain (BRG)) and non-invasive haemodynamics (cardiac output and total peripheral resistance) in patients with neurocardiogenic syncope. Retrospectively, we evaluated 12 NCS patients (positive head-up tilt without pharmacological provocation) in the basal state and at initial tilt, 12 non-NCS patients with tilt-negative syncope and 12 aged-matched normal controls. Prospectively, we evaluated 16 NCS patients to analyse the haemodynamics and ANS activity throughout the tilt test (beginning of tilt and before syncope occurs). HRV and SBPV were accessed by fast Fourier transforms (FFT) and spontaneous BRG by temporal sequences, slope and a index. Modelflow was used to quantify the non-invasive haemodynamics. None of the autonomic and haemodynamic parameters at baseline or in the first 10 min of tilt was different among the respective NCS, non-NCS syncope and normal control groups, except for SBP, which was higher at baseline in controls. Throughout the tilt test in the prospective NCS group, the heart rate increased (88-95 beats x min(-1), P<0.05), systolic blood pressure decreased (123-109 mmHg, P<0.01), and arterial baroreceptor gain was reduced (7.6 to 5.5 ms mmHg(-1), P<0.01) and the absolute high frequency component of HRV (HF HRV) decreased (150-80 ms(-2), P<0.05), before syncope occurred. There was no change in the low frequency component of HRV (LF HRV), SBPV, cardiac output (CO) or total peripheral resistance (TPR). Tilt-induced syncope could not be predicted by non-invasive haemodynamic or autonomic parameters at rest or in the initial minutes of tilt. The decrease in arterial baroreceptor gain could be a precocious expression of the transient autonomic dysfunction that characterizes the occurrence of neurocardiogenic syncope.

Adult↗
PubMed1998

Transforming growth factor beta 1 binding and receptor kinetics in fetal mouse lung fibroblasts.

TGFbeta1 inhibits fetal lung maturation in vitro. As TGFbeta1 is present in fetal lung, mechanisms must exist to overcome this inhibition and allow late gestation maturation to progress. We studied the ontogeny of TGFbeta1 binding, and TGFbeta receptor kinetics and subtypes in primary cultures of fetal mouse lung fibroblasts from Day 16 to Day 18 of gestation. TGFbeta1 specific binding in fetal lung fibroblasts declined with advancing gestation. The decrease occurred earlier, and was more pronounced in female fibroblasts (50% decrease) than in the male fibroblasts (29% decrease). Dihydrotestosterone treatment of Day 18 female fibroblasts resulted in a dose-dependent increase in TGFbeta1 binding. Scatchard analysis revealed a decline in receptor number with advancing gestation (Day 16 female Bmax: 7.3 x 10(-16); Day 18 female Bmax: 5.5 x 10[-16]) whereas binding affinities remained constant. Affinity labeling followed by chemical cross-linking and autoradiography showed the three known TGFbeta receptor subtypes at both Days 16 and 18 of gestation. The relative abundance of nonsignaling Type III receptors in comparison to signaling Type II and Type I receptors was increased at Day 18 versus Day 16. Incorporation of [3H]thymidine into DNA after treatment with TGFbeta1 changed from Day 16 to Day 18, consistent with changes previously reported between fetal and adult lung fibroblasts. We conclude that as fetal mouse lung maturation progresses, TGFbeta receptor number decreases in fibroblasts, the relative proportion of nonsignaling versus signaling receptor types increases, and the response to TGFbeta1 stimulation changes. These changes may contribute to overcoming TGFbeta1 inhibition of lung maturation.

Animals↗
PubMed1998

[The initial loss of consciousness in spontaneous subarachnoid hemorrhage. What does it mean?].

BACKGROUND AND PURPOSE: Poor outcome and rebleeding, after admission to hospital of patients with spontaneous subarachnoid hemorrhage (SAH) has been found to be predicted by loss of consciousness at ictus (LOCi). In this study, we assessed the clinical and neuro-radiological significance of the LOCi in non-traumatic SAH. PATIENTS AND METHODS: The authors retrospectively studied 102 patients with SAH admitted to S. João Hospital between January 1, 1989 and December 31, 1992, who were divided into two groups with and without LOCi and compared according to clinical and imaging features. RESULTS: Loss of consciousness at ictus was statistically associated with an age over 52 years (odds ratio, 2.9; 95% confidence interval, 1.1-7.8); a Hunt and Hess Scale score > ou = 3 (4.4; 1.6-12.3); finding of subarachnoid blood on initial cranial CT scan (5.5; 1.4-26.3); existence of aneurysm (3.4; 1.3-8.9); a Glasgow Outcome Scale score > ou = 3 (4.69; 1.6-14.1). A poor clinical condition on admission (5.2;1.8-14.5) and existence of aneurysm (4.1; 1.6-10.6) were the only two findings shown to have an independent power of significant association with loss of consciousness at ictus, using logistic regression analysis, with LOCi as a dependent variable. CONCLUSIONS: In this study, LOCi has independent predictive power for a poor neurologic condition on admission and for the finding of aneurysm on angiogram. Loss of consciousness at ictus may be explained by the direct impact of the initial hemorrhage on the brain from a large tear in the aneurysmal wall, causing a quick rise in intracranial pressure (with LOCi) but a relatively short bleeding time.

Brain↗
PubMed1998

[Fatal liver necrosis due to allopurinol].

Allopurinol hypersensitivity syndrome (AHS) is a severe reaction which is potentially lethal. Exanthematous rash, fever, eosinophilia, and other severe reactions such as toxic epidermal necrolysis, acute vasculitis, and severe hepatic and renal dysfunctions are manifestations of this syndrome. The authors report a case of lethal massive hepatic necrosis due to allopurinol in a patient with the asymptomatic hyperuricemia. They also describe the risk factors most frequently associated with the development of AHS and the strategy for its prevention and consequent reduction of the mortality associated with this syndrome.

Aged↗
PubMed1997

Cytotoxic T-cell clone against rectal carcinoma induced by stimulation of a patient's peripheral blood mononuclear cells with autologous cultured tumor cells.

In an effort to establish cytolytic T lymphocytes (CTLs) against colorectal carcinoma (CRC) by stimulating patients' lymphocytes with autologous tumor cells, we used peripheral blood mononuclear cells (PBMC) from a patient with minimal residual rectal carcinoma following removal of the primary lesion and involved regional lymph nodes as a source to generate CTLs in culture. A CTL line and clone were established from the patient's PBMC following stimulation of PBMC with autologous, cultured tumor cells and interleukin-2. The CTL line and the clone consisted predominantly of CD4+ lymphocytes. The CTL clone expressed two T-cell receptor variable alpha chains (V alpha11 and V alpha22) and one beta chain (Vbeta14). The cytokine secretion pattern of the CTL line was of the Th1-type. Both the CTL line and the clone lysed the autologous rectal carcinoma cells, but not the allogeneic, partially human lymphocyte antigen (HLA)-matched or nonmatched CRC cells, autologous Epstein-Barr virus-transformed B cells, K562 (natural killer target) cells or Daudi (lymphokine-activated killer target) cells. Lysis of autologous tumor cells most likely was HLA class I-restricted. Our unique success in generating CTLs against this tumor type may rest in the inclusion of a patient with minimal residual, rather than advanced, disease.

Amino Acid Sequence↗
PubMed1997

A model system for detection and isolation of a tumor cell surface antigen using antibody phage display.

To establish a screening procedure for tumor cell-surface reactive Fabs, we used a model antigen/antibody system including the epidermal growth factor receptor (EGF-R) and the anti-EGF-R monoclonal antibody 425. The 425 Fab was displayed on the surface of M13 filamentous phage. In a screening assay for 425 phage binding to tumor cell surfaces, biotinylated 425-phage bound specifically to EGF-R-positive A431 epidermoid carcinoma cells and not to K562 non-expressor erythroleukemia cells. With a model library, the sensitivity of phage enrichment by phage binding to cell surfaces was one 425-phage in 20,000 unrelated phages after 4 rounds of panning on A431 cells. In a phage tissue screening assay, 425-phage, but not unrelated phage, bound specifically to melanoma cells expressing EGF-R. Epitope and idiotope specificity of 425-phage was demonstrated in phage competition assays, using as targets A431 cells and anti-idiotypic antibodies to monoclonal antibody 425, respectively. Finally, the EGF-R protein was directly isolated from A431 cell extracts, using biotinylated 425-phage. The data obtained with the 425 model library system demonstrate the usefulness of antibody phage display for the rapid identification and isolation of tumor or other disease-related cell surface antigens.

Adenocarcinoma↗
PubMed1997

Prenatal diagnosis of partial trisomy 2q. Case report.

A case of partial trisomy 2(q21q33) detected by cordocentesis at 27 weeks' gestation in a polymalformed fetus is described. This is the second case of a prenatally detected de novo duplication of 2q and the first involving the region referred to above.

Adult↗
PubMed1997

Missense mutation R1066C in the second transmembrane domain of CFTR causes a severe cystic fibrosis phenotype: study of 19 heterozygous and 2 homozygous patients.

We report the clinical features of 21 unrelated cystic fibrosis (CF) patients from Portugal and Spain, who carry the mutation R1066C in the CFTR gene. The current age of the patients was higher in the R1066C/any mutation group (P < 0.01), as compared to the deltaF508/deltaF508 group. Poor values for lung radiological involvement (Chrispin-Norman) and general status (Shwachman-Kulcycki) were observed in the R1066C/any mutation group (P < 0.005 and P < 0.0004). A slightly, but not significantly worse lung function was found in the R1066C/any mutation group when compared with the deltaF508/deltaF508 patients. No significant differences were detected regarding the age at diagnosis, sweat Cl-values, or percentiles of height and weight between the two groups. Neither were significant differences observed regarding sex, meconium ileus (4.7% vs. 11.1%), dehydration (10.5% vs. 14.7%), or pancreatic insufficiency (PI) (100% vs. 97.8%). The proportion of patients with lung colonization by bacterial pathogens was slightly, but not significantly higher in the R1066C/any mutation group (70.0%), as compared with the deltaF508/deltaF508 group (57.5%). Other clinical complications were significantly more frequent in the R1066C/any mutation patients(P < 0.02) than in the deltaF508/deltaF508 group. The two homozygous R1066C/R1066C patients died at the ages of 3 months and 7 years. The data presented in this study clearly demonstrate that the R1066C mutation is responsible for a severe phenotype similar to that observed in homozygous deltaF508 patients. The poor clinical scores and complications of patients with the R1066C mutation are probably related to their slightly longer survival.

Adolescent↗
PubMed1997

Cardosin A, an abundant aspartic proteinase, accumulates in protein storage vacuoles in the stigmatic papillae of Cynara cardunculus L.

The function of aspartic proteinases (EC 3.4.23) present in flowers of Cynara species is still unknown. Cardosin A, as a highly abundant aspartic proteinase from Cynara cardunculus L., a relative of the artichoke, is synthesised as a zymogen and subsequently undergoes proteolytic processing, yielding the mature and active enzyme. Here we report the study of the expression and localization of cardosin A, as a first approach to address the question of its physiological relevance. A polyclonal antibody specific for cardosin A was raised against a synthetic peptide corresponding to an amino acid sequence of the enzyme. This antibody was used to study the organ-specific, tissue-specific and subcellular localization of cardosin A by immunoblotting, tissue printing and immunogold electron microscopy. The results showed that expression of cardosin A is highly restricted to the pistils, and that the enzyme accumulates mainly in protein storage vacuoles of the stigmatic papillae. Cardosin A is also present, although much less abundantly, in the vacuoles of the cells of the epidermis of the style. In view of these results, the possible physiological roles of cardosin A are discussed, namely an involvement in defense mechanisms or pollen-pistil interaction, as well as in flower senescence.

Amino Acid Sequence↗
PubMed1997

Cytomegalovirus enteritis in a premature infant.

BACKGROUND/PURPOSE: Up to 2.5% of newborn infants are cytomegalovirus (CMV) positive at birth. Five percent will be symptomatic at birth, including cytomegalic inclusion disease. Symptoms such as hearing loss and mental retardation will ultimately develop in 15%. METHODS: The authors describe a case of CMV enteritis in a 2.2-kg newborn that presented as necrotizing enterocolitis (NEC) and subsequently developed a colonic stricture. RESULTS: There are four reports of neonatal CMV enteritis in the nonEnglish-language literature. Cytomegalovirus enteritis has become prevalent among the immunosuppressed pediatric and adult patient population. CONCLUSIONS: We propose the addition of CMV to the list of pathogens responsible for NEC. A review of neonatal CMV infection is provided.

Cytomegalovirus Infections↗
PubMed1997

Combinatorial antibodies against human malignant melanoma.

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 antigens in patients. We have attempted to identify melanoma-associated antigens recognized by patients' B cells using an antibody phage display approach. Antibody display on filamentous phages allows direct screening of cDNA libraries for expression of cell-surface-reactive antibodies, without the need for antibody production and purification using bacteria or eukaryotic cell systems. This approach was used to identify melanoma-associated cell-surface antigens recognized by patients' B cells. Antibodies produced by the B cells of a melanoma patient (in remission for > 7 years following periodic vaccination with allogeneic melanoma cell vaccine) were displayed as Fabs on the surfaces of filamentous phages. A library of 10(8) phages was absorbed to normal melanocytes, followed by phage binding to and elution from melanoma cells (human lymphocyte antigen nonmatched and vaccine melanoma cells). Phages were further selected for reactivities with tunicamycin-treated melanoma cells. These procedures resulted in a > 10(6)-fold enrichment of tumor-specific phages from the original phage library. One phage-Fab bound to melanoma cells, other tumor cells, and a few normal cells in cultured cell lines and in tissue sections.

Antibodies, Neoplasm↗
PubMed1997

A survey of the attitudes of chronic psychiatric patients living in the community toward their medication.

Because non-compliance with antipsychotic drug therapy is both common and associated with a substantially increased risk of acute relapse, depot medication must be preferred for most schizophrenic out-patients. Yet there is a perception that depot medication is unpopular among patients. In the survey of out-patients reported here, the great majority of patients receiving either oral or depot neuroleptics (with or without oral augmentation) would, given a free choice, elect to continue with their present dose form (94% and 87%, respectively). In virtually all cases, the choice of route was made by the treating physician and readily accepted by the patient. These findings suggest that physicians should more often recommend and prescribe depot medication when antipsychotic maintenance therapy is indicated.

Administration, Oral↗
PubMed1997

Does pulmonary tuberculosis change with ageing?

SETTING: In most low prevalence countries, tuberculosis has become a disease of the aged; it has recently been suggested that the elderly may present a specific pattern. OBJECTIVE: To compare clinical, bacteriological and radiological features of pulmonary tuberculosis between young and elderly populations in a high incidence country. PARTICIPANTS AND METHODS: We retrospectively studied 337 consecutive pulmonary tuberculosis patients without confirmed HIV infection, hospitalised from 1989 to 1993. The clinical, bacteriological and radiological features of the two age groups considered, young adults (< 60 years) and elderly (> or = 60 years), were compared. RESULTS: Thoracic pain (16.3% vs 32.7%) and fever (27.2% vs 50.6%) were significantly less frequent in the elderly, while the frequency and duration of other symptoms before hospitalisation were similar. After admission, fever remained longer in young patients (P < 0.05). No significant differences were found regarding the general health status at hospitalisation, or associated illnesses (83.7% vs 73.5%; P = 0.068). Radiological lesions not related to the present diagnosis (14.1% vs 2.0%; P < 0.05), and a presumed diagnosis of tuberculosis (11.7% vs 4.1%; P = 0.02) were more frequent in the elderly. CONCLUSION: This study showed no specific clinical, bacteriological or radiological features between age groups, and does not support the hypothesis of any age-related patterns in pulmonary tuberculosis.

Adolescent↗
PubMed1996

Mutagenic activity of glycine upon nitrosation in the presence of chloride and human gastric juice: a possible role in gastric carcinogenesis.

The mutagenic activity of glycine upon nitrosation was studied in the Ames tester strains TA98, TA100, TA102, and TA104. The results obtained show that glycine at acidic pH values and in the presence of Cl- can react with nitrite giving rise to genotoxic compounds to the tester strains used. When these experiments were carried out in the presence of gastric juice the genotoxicity observed was associated with the Cl- concentration in the different gastric juice samples. The nature and the mechanism of genetic lesion induced by the ultimate genotoxicant arising from the nitrosation of glycine are not fully understood. Primary amines (e.g., amino acids) have been described as potential alkylating agents after nitrosation. However, in our experimental conditions these alkylating activities were not detected, suggesting that other mechanisms could be involved in the genetic lesion induced by nitrosated glycine. The influence of Cl- in the genotoxic activity of glycine and other primary amines upon nitrosation and its possible involvement in the etiology of gastric cancer are discussed.

Chlorides↗