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Biomedical subjects

A Albuquerque

Publications and source records attributed to A Albuquerque.

15 recordsLinked to original sources
PubMed2005

Physical chemistry of nanostructured molecular sieves by the study of phase diagrams: the case of the cetyltrimethylammonium bromide-tetramethylammonium silicate-water system.

A phase diagram for the system cetyltrimethylammonium bromide (CTAB)/tetramethylammonium silicate (TMASi)/water has been constructed in order to better understand the interactions between these precursors of the MCM-41 mesoporous molecular sieves. Three different CTAB concentration regions were analyzed: the dilute and semidilute regions, where simple surfactant species, such as monomers and spherical and nonspherical CTAB micelles, are found, and the concentrated region, involving liquid-crystalline phases. In the dilute and semidilute regions, the formation of a white nanostructured solid, having a hexagonal array similar to that found in MCM-41 materials, was observed. Precipitation of this solid requires some degree of surfactant monomer aggregation, which is favored by the presence of silicate anions. If micelles have already been formed, the material can be obtained at any CTAB concentration above a threshold concentration of silicate anions. These facts suggest that silicate anions have an important role in changing the aggregation and/or the shape of the surfactant aggregates. In the concentrated region, precipitation of the solid was not observed, but the presence of the silicate anions alter the characteristics of the liquid-crystalline phase formed by the surfactant. The system shows very complex and rich behavior and its investigation may be very useful in understanding the processes of nanostructured solid formation.

Journal Article↗
PubMed2001

Interleukin 8 as a vaso-occlusive marker in Brazilian patients with sickle cell disease.

Sickle cell disease has a worldwide distribution and is a public health problem in Brazil. Although vaso-occlusive crisis (VOC) is one of the most important clinical features of the disease, there are still several steps of its pathogenesis which are unknown. The increase of the chemotactic factor interleukin 8 (IL-8) has been reported to be involved in sickle cell disease crisis, but this has not been demonstrated conclusively. In the present study we analyzed serum IL-8 levels by ELISA and hematological parameters and hemoglobin patterns by standard techniques in 23 (21 SS and 2 SC) Brazilian patients with sickle cell syndromes during VOC caused by different inducing factors, 22 (21 SS and 1 SC) sickle cell patients out of crisis, and 11 healthy controls. Increased IL-8 levels were observed in 19 of 23 VOC patients (79.2%), 3 of them with more than 1,000 pg/ml. Seventeen of 22 (77.3%) non-crisis patients showed low IL-8 levels (less than 15 pg/ml). Healthy controls had low IL-8 levels. A significant difference in serum IL-8 levels was observed between crisis and non-crisis sickle cell patients (P<0.0001). There was no correlation between IL-8 levels and hematological data or hemoglobin patterns. High serum IL-8 levels were observed in VOC patients independently of the crisis-inducing factor. We conclude that in the studied population, IL-8 concentration may be a useful VOC marker, although the mechanism of the pathogenic process of sickle cell VOC syndromes remains unclear.

Adolescent↗
PubMed2001

[Arterial blood pressure behavior during the administration of intravenous streptokinase, in patients with acute myocardial infarction].

OBJECTIVE: To evaluate the effect on blood pressure (BP) of intravenous (i.v.) streptokinase (SK) in patients (PTS) with acute myocardial infarction (AMI). DESIGN: Retrospective study with analysis of BP registers ten minutes before and during SK infusion. SETTING: PTS admitted to the Coronary Care Unit (CCU) of Santo António Hospital, Oporto. PATIENTS: Thirty-eight male PTS, average ages of 54, ranging from 38 to 67, AMI confirmed, and criteria to thrombolytic therapy. One patient was excluded on account of persistent hypotension since admission. MATERIAL AND METHODS: I.v. infusion of 1.500.000 U of SK over 60 minutes, preceded by 200 mg i.v. of prednisolone. BP and heart rate (HR) were evaluated with Datascope Accutorr 1A set. The lowest value of the systolic BP (SBP) recorded ten minutes before SK infusion was considered the baseline value. We valued the reduction of SBP above 15%, defining its fall as the difference between the baseline value and the minimum value of SBP recorded during the infusion. Hypertension was defined to SBP values below 90 mmHg. MAIN RESULTS: The fall was 40.4 +/- 22.1 mmHg (range 9 to 102, having been recorded the minimum value at 22.9 +/- 10.9 minutes. It was accompanied by diastolic BP (DBP) fall of 30.6 +/- 18.9 mmHg (range -2 to 76) and by a HR increasing from 76.2 +/- 13.7 beats/min. to 80.8 +/- 14.1 beats/min. (p < 0.01). In 86% of the PTS this fall was transient, lasting 8.9 +/- 6.3 minutes, and was corrected by slowing or stopping the infusion for a few minutes and placing the patient in Trendelenburg position. Two PTS needed sympaticomimetic amines because of persistent BP reduction despite the previous measures. 92% of the PTS had a SBP fall higher than 15% in relation to the baseline value. The SBP was kept over 90 mmHg in 20 PTS (54%); hypotension was recorded in the remaining 14 PTS (38%), and in 10 (27%) of these the SBP fell below 80 mmHg. We couldn't prove that the infarction and the extension of the ischemic lesion had influenced this BP fall. CONCLUSIONS: The BP reduction during treatment with high doses of SK deserves some attention because, although transient and easily reversible, it is frequent and sometimes significative. It demands then careful monitoring in order to avoid the hypoperfusion to the ischemic myocardium, that could jeopardize the potential benefits of reperfusion in the reduction of infarction area, the main objective of the thrombolytic treatment.

Adult↗
PubMed2000

Loss of heterozygosity in P53, BRCA1, and estrogen receptor genes and correlation to expression of p53 protein in ovarian epithelial tumors of different cell types and biological behavior.

Loss of heterozygosity (LOH) of tumor suppressor genes (TSGs) in ovarian epithelial tumors of differing cell types and biological behavior has not been thoroughly investigated. Moreover, there have been conflicting reports correlating LOH of the p53 gene to overexpression of p53 protein. This study evaluated 34 formalin-fixed, paraffin-embedded ovarian epithelial tumors for LOH by polymerase chain reaction (PCR) for the following microsatellite markers: TP53(17p13.1/p53 gene), D17S579(17q/BRCA1 gene), and ESR (6q24-27/estrogen receptor gene). LOH of the TP53 marker was detected in 4 (44%) of 9 informative serous cystadenocarcinomas (SCa) but in 0 of 4 informative clear cell carcinomas (CCa) and 0 of 5 informative serous tumors of low malignant potential (SLMP). LOH of the BRCA1 marker was detected in 5 (83%) of 6 informative SCa, but in 1 (13%) of 8 informative CCa and 1 (14%) of 7 informative SLMP. LOH of the ESR marker was detected in 4 (50%) of 8 informative SCa, but in 0 of 4 informative CCa and 1 (16%) of 6 informative SLMP. p53 protein overexpression was present in 8 of 12 SCa but did not correlate to TP53 LOH. LOH for TP53, D17S579/ BRCA1, and ESR is common in ovarian SCa, and is observed in primary tumors as well as metastases. In contrast, these genetic alterations are less common in CCa and in the biologically less aggressive SLMP tumors. These data suggest different mechanisms of oncogenesis in ovarian epithelial tumors of different cell types and biological behavior.

Adenocarcinoma, Clear Cell↗
PubMed1999

The use of microsatellite instability in the distinction between synchronous endometrial and colonic adenocarcinomas.

The association of endometrial carcinoma with other gynecologic neoplasms, especially ovarian and fallopian tube carcinoma, has been well documented and is usually interpreted as a result of a field defect. Sporadic synchronous primary carcinomas occurring in the endometrium and colon are extremely rare, especially in the absence of the familial genetic abnormalities seen in hereditary nonpolyposis colorectal carcinoma (HNPCC) syndrome, and may present a diagnostic dilemma. Two cases of synchronous adenocarcinomas of the endometrium and colon were studied for genetic abnormalities and differences to test for the presence of two primary tumors. Primary tumors, metastases, and normal tissues were microdissected from formalin-fixed, paraffin-embedded tissues. PCR amplification was performed for microsatellite DNA markers on chromosome 17q and 11q13. The colonic tumors were moderately and poorly differentiated, invasive, nonmucinous adenocarcinomas, whereas one uterine tumor was endometrioid adenocarcinoma and the other was papillary serous carcinoma. Although microsatellite instability, as evidenced by changes in the lengths of the amplified PCR products, was detected at 17q and 11q13 loci in the uterine and colonic neoplasms, the patterns of instability differed between the two primary tumor sites. Moreover, the lymph node metastasis in one colonic tumor had genetic alterations that differed from that of the primary tumor. In both patients, the molecular studies suggested the presence of two synchronous primary tumors. Molecular techniques may assist in distinguishing two separate primaries by determining the contraction and expansion of microsatellite regions in DNA obtained by microdissection from the primary tumors and associated metastases.

Adenocarcinoma↗
PubMed1997

Identical clonality of both components of mammary carcinosarcoma with differential loss of heterozygosity.

The histogenesis of carcinosarcomas is controversial, specifically with respect to clonality and cell of origin. To answer these questions, tumor cells from both epithelial and spindle-cell components were microdissected from three cases each of mammary carcinosarcoma and its postulated precursor, carcinoma with spindle-cell metaplasia. Clonality was assessed using the principle of X chromosome inactivation. Loss of heterozygosity (LOH) was evaluated at seven chromosomal loci to assess shared and distinctive genetic alterations for the two components in each tumor. All of the six cases demonstrated identical clonality of the carcinomatous and spindle-cell components, identical to a focus of ductal carcinoma in situ present in one case. LOH for NM23 was detected in both components in one carcinosarcoma, whereas LOH for INT-2 was detected in both components in one metaplastic carcinoma. Differential LOH for D11S904 was present in only the mesenchymal components of these two cases. We conclude that the two components of carcinosarcoma and its precursor are clonal and that the sarcomatous and spindle-cell components arise from mutation of the carcinoma. Presence of differential LOH at D11S904 in only the spindle-cell components suggests that this mutation might be critical to the development of this second phenotype.

Breast Neoplasms↗
PubMed1995

Substituted thiazolidinediones and thio-imidazolidinones: synthesis, structural study and pharmacological activity.

Synthesis and physico-chemical properties of six 3-(4-bromophenacyl)-5-arylidene-thiazolidine-2,4-diones and eight 3-(4-chlorobenzyl)-5-arylidene-4-thio-imidazolidine-2-ones are described. These products were synthesized by an aldolisation-crotonisation reaction from aromatic aldehydes and 3-substituted thiazolidine-2,4-diones or 4-thio-imidazolidine-2-ones. Hypoglycemic and peripheral antinociceptive activities were investigated for these compounds.

Alkylation↗
PubMed1992

3-D computer animation of electrophysiological responses.

Traditional methods for displaying electrophysiological data, that use time as the axis on a plot, are inadequate for displaying data from simultaneous multi-channel recordings. New methods proposed here plot the instantaneous value of the data on a third axis over a 2-dimensional spatial map of the tissue. The resulting 3-D computer-generated surfaces are animated over time to reveal simultaneous coherent waves of activity over the entire slice. This method was implemented for displaying multi-channel evoked potential data from rat hippocampal and human cortical slices. In rat hippocampal slice, stimulation of the Schaffer collateral-commissural pathway in stratum radiatum (SR) near CA2 elicited evoked extracellular responses along the length of CA1 from the alveus to stratum lacunosum moleculare (SLM). 3-D plotting and subsequent animation of these responses translated differential latencies of activation elicited across the slice into coherent moving patterns. These evoked waves of extracellular activity appeared to propagate along hippocampal laminae and were not readily visible in the individual plots. Human temporal cortical slices were stimulated in the white matter and evoked responses recorded in an array format. Upon plotting and animation, activity was seen to propagate vertically to the pial surface and thereafter move radially away from the stimulation site. Animation of 3-D plots of electrophysiological activity can provide instantaneous visual information on correlated changes in amplitude and latency over an entire brain slice. This means of displaying data can reduce a large number of complex wave forms to simple events and allow the simultaneous visualization of general patterns of activity in a large group of neurons.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

[Value of transesophageal echocardiography in the diagnosis of acute aortic dissection].

We describe our experience of six patients with clinical suspicion of acute aortic dissection (AAD) who were studied consecutively by transesophageal echocardiography (TEE) from April to July of 1991. All of them were previously submitted to transthoracic echocardiogram. The diagnosis was correctly established by TEE in five cases, confirmed by aortography and/or surgery (four cases), or by autopsy (one case). In one patient the diagnosis of AAD was excluded by TEE, and posteriorly by nuclear magnetic resonance. Four patients had a Stanford type A, and one patient a type B dissection. The site of entry was identified in three cases; the intimal entry tear of the type B dissection, not observed by TEE, was localized in the aortic arch by aortography. In three of the four type A dissection cases, a thrombus in the false lumen and an aortic regurgitation were found. No other noninvasive methods were used after the diagnosis of AAD by TEE. The surgical repair was successful in three cases, one of which, without previous necessity of aortography. In our experience, TEE increased extraordinarily the diagnosis efficacy of AAD, making possible an earlier therapeutic approach, and probably contributing to the improvement of the prognosis of this pathology.

Acute Disease↗
PubMed1991

[Transcutaneous pacemaker in cardiovascular emergencies].

UNLABELLED: OBJECTIVES AND DESIGN OF THE STUDY: Retrospective study to evaluate the efficacy and tolerance of the transcutaneous cardiac pacemaker in the urgent treatment of asystole or severe bradycardia. SETTING: Coronary Care Unit (CCU) and emergency area of the central reference Hospital. PATIENTS: 24 patients, 20 males and four females, aged between 57 and 84 years (mean 70.4 +/- 7.9). Five pts were in asystole and 19 in severe bradycardia. INTERVENTIONS: The transcutaneous pacemaker used, was the "Cardio Aid Zoll NTP" model. The intensity of the electrical stimulation was increased progressively, until electrical capture or intolerable discomfort by the patients was achieved. We defined by electric efficacy, the visualization of pacing spike followed by a deflection due to ventricular depolarization; and by hemodynamic efficacy, the evidence of myocardial contraction, defined as a palpable pulse, synchronous with the pacing artefact. MAIN RESULTS: Stimulation threshold ranged from 30 to 140 mA (mean 67.7 +/- 23.4). The duration of pacing was from 15 minutes to 13 hours, being more than one hour in only four situations. From the 20 conscious patients, or the ones who got conscious, 15 (75%) tolerated well the stimulation. It was intolerable in five pts (25%). No significative side effects due to the use of transcutaneous pacemaker were observed. CONCLUSIONS: The transcutaneous pacemaker was efficient in the electric and hemodynamic stabilization in the majority of patients. It was generally well tolerated and without important side effects. We think that it may be a valid alternative to transvenous pacing technics in the treatment of asystole and severe bradycardia situations.

Aged↗
PubMed1991

[Indirect criteria of coronary reperfusion and permeability in patients with acute myocardial infarction who have received thrombolytic therapy].

OBJECTIVE: To evaluate the value of some indirect reperfusion signs (IRS) as markers of coronary artery patency in patients (PTS) with acute myocardial infarction (AMI) submitted to intravenous (IV) thrombolytic therapy (TT). DESIGN: Retrospective study, with analysis of the sensibility (S), specificity (SP) and predictive value (PV) of three IRS: 1. Pain and ST resolution in the first three hours; 2. Peak CK in the first 13 hours; 3. accelerated idioventricular rhythm (AIVR) in the first three hours. SETTING: Coronary Care Unit (CCU) of the Santo António Hospital and Hemodynamic Laboratory of the S. João Hospital, Oporto. PATIENTS: Sixty seven PTS (mean age 53.4 +/- 10.6 years) with confirmed AMI, 62 male and five female, 34 with anterior and 33 with inferior infarction, TT started in the first three hours of the beginning of symptoms in 34 PTS and from three to six hours in 33 PTS, all submitted to coronary angiography in the hospital setting (7.6 +/- 5.9 days after AMI). INTERVENTIONS: IV administration of 1,500,000 U of streptokinase (SK) in 47 PTS and 30 U of APSAC in 20 PTS, preceded by 200 mg IV prednisolone and oral 100 mg acetilsalicylic acid, and followed by IV heparin therapy. Continuous electrocardiographic monitoring, and serial 12 leads ECG and enzymatic assays (at start and 1, 3, 7, 13 and 25 hours of TT). Analysis of the correlation of the three IRS (isolated and in association) with coronary artery patency (TIMI 2 or 3). MEASUREMENTS AND RESULTS: The total patency rate was 79.1%; there was no statistically significant difference with regard to AMI location, time of symptoms onset (0-3 vs 3-6 hours) or thrombolytic agent (SK vs APSAC). The first and second IRS had a high S and a low SP; together S = 79.2%, SP = 64.3% and PV = 89.4%. The third IRS with the first and/or the second one had a low S (about 25%) but SP and PV of 100%. The coronary patency rate of PTS without IRS was always greater than 50%. CONCLUSIONS: The analysed IRS although not very reliable are useful when considered in association. It is possible to assess PTA with high probability of reperfusion if AIVR is present. The absence of IRS does not exclude coronary artery patency. There is still missing more reliable no-invasive reperfusion markers.

Adult↗
PubMed1989

[Behavior of arterial pressure during administration of intravenous streptokinase, in patients with acute myocardial infarct].

OBJECTIVE: To evaluate the effect on blood pressure (BP) of intravenous (IV) streptokinase (SK) in patients (PTS) with acute myocardial infarction (AMI). DESIGN: Retrospective study with analysis of BP registers ten minutes before and during SK infusion. SETTING: PTS admitted to the Coronary Care Unit (CCU) of Santo António Hospital, Oporto. PATIENTS: Thirty-eight male PTS, average ages of 54, ranging from 38 to 67, AMI confirmed, and criteria to thrombolytic therapy. One patient was excluded on account of persistent hypotension since admission. MATERIAL AND METHODS: IV infusion of 1,500,000 U of SK over 60 minutes, preceded by 200 mg IV of prednisolone. BP and heart rate (HR) were evaluated with a Datascope Accutorr 1A set. The lowest value of the systolic BP (SBP) recorded ten minutes before SK infusion was considered the baseline value. We valued the reduction of SBP above 15%, defining its fall as the difference between the baseline value and the minimum value of SBP recorded during the infusion. Hypotension was defined to SBP values below 90 mmHg. MAIN RESULTS: The SBP fall was 40.4 +/- 22.1 mmHg (range 9 to 102), having been recorded the minimum value at 22.9 +/- 10.9 minutes. It was accompanied by diastolic BP (DBP) fall of 30.6 +/- 18.9 mmHg (range -2 to 76) and by a HR increasing from 76.2 +/- 13.7 beats/min. to 80.8 +/- 14.1 beats/min. (p less than 0.01). In 86% of the PTS this fall was transient, lasting 8.9 +/- 6.3 minutes, and was corrected by slowing or stopping the infusion for a few minutes and placing the patient in Trendelenburg position. Two PTS needed sympaticomimetic amines because of persistent BP reduction despite the previous measures. 92% of the PTS had a SBP fall higher than 15% in relation to the baseline value. The SBP was kept over 90 mmHg in 20 PTS (54%); hypotension was recorded in the remaining 14 PTS (38%), and in 10 (27%) of these the SBP fell below 80 mmHg. We couldn't prove that the infarction location and the extension of the ischemic lesion had influenced this BP fall. CONCLUSION: The BP reduction during treatment with high doses of SK deserves some attention because, although transient and easily reversible, it is frequent and sometimes significative. It demands then careful monitoring in order to avoid the hypoperfusion to the ischemic myocardium, that could jeopardize the potential benefits of reperfusion in the reduction of infarction area, the main objective of the thrombolytic treatment.

Adult↗