Search PubMed⌕ Search

Biomedical subjects

P Matos

Publications and source records attributed to P Matos.

14 recordsLinked to original sources
PubMed2000

Small GTPase Rac1: structure, localization, and expression of the human gene.

Rac1 is a member of the Rho family of small GTPases involved in signal transduction pathways that control proliferation, adhesion, and migration of cells during embryonic development and invasiveness of tumor cells. Here we present the complete structure of the human RAC1 gene and characterize its expression. The gene comprises 7 exons over a length of 29 kb and is localized to chromosome 7p22. The GC-rich gene promoter shows characteristics of a housekeeping gene and Northern blot studies revealed ubiquitous expression of two rac1 transcripts, 1.2 and 2.5 kb in size. The two transcripts are expressed in tissue-specific ratios, reflecting competition between two alternative polyadenylation sites. The RAC1 but not RAC2 gene contains an additional exon 3b that is included by alternative splicing into the variant Rac1b, a constitutively active mutant which induces the formation of lamellipodia in fibroblasts. These data indicate that the RAC1 gene encodes two signaling GTPases. The gene structure reported here will enable studies on the regulation of RAC1 expression during tumorigenesis and development.

5' Untranslated Regions↗
PubMed2000

Four novel MSH2 / MLH1 gene mutations in portuguese HNPCC families.

Hereditary non-polyposis colorectal cancer (HNPCC) is considered to be determined by germline mutations in the mismatch repair (MMR) genes, especially MSH2 and MLH1. While screening for mutations in these two genes in HNPCC portuguese families, 3 previously unreported MSH2 and 1 MLH1 mutations have been identified in families meeting strict Amsterdam criteria. Hum Mutat 15:116, 2000.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Eleven novel APC mutations identified in Portuguese FAP families.

Germline mutations of the adenomatous polyposis coli (APC) gene are responsible for familial adenomatous polyposis (FAP), an autosomal dominant predisposition to colorectal cancer. In the present study we screened all of the exons of the APC gene in individuals belonging to 85 Portuguese FAP families. We here report eleven novel mutations which are predominantly frameshifts or single base substitutions, resulting in premature stop codons. Hum Mutat 16:178, 2000.

Adenomatous Polyposis Coli↗
PubMed1998

Creatinine reabsorption by the newborn rabbit kidney.

Plasma creatinine levels are elevated in the first postnatal days, and the highest plasma creatinine values are observed in the most premature infants. These high plasma creatinine levels remain "elevated" beyond the period in which the high plasma creatinine levels can be explained by maternal transfer of creatinine. To better define the renal handling of creatinine by the immature kidney, creatinine and inulin clearances were simultaneously measured in two groups of neonatal and one group of adult anesthetized, ventilated rabbits. In the adult animals the ratio of the creatinine and inulin clearance was as expected more than one (1.21), indicating an overestimation of the true GFR due to tubular secretion of creatinine. The creatinine and inulin clearance ratio in the first group of newborn animals, who received an exogenous creatinine infusion to achieve plasma creatinine levels comparable to those in the adult animals (84.1 +/- 1.0 mumol/L; 0.95 +/- 0.01 mg/dL), was 0.84. When in the second group of neonatal animals the plasma creatinine level was artificially doubled to 155.0 +/- 3.9 mumol/L (1.33 +/- 0.17 mg/dL), no significant difference between both clearance values was found (ratio: 0.96). These data show that in the newborn rabbit creatinine is reabsorbed along the tubule, an observation that can best be explained by the back-leak of creatinine across leaky immature tubules.

Absorption↗
PubMed1992

[Civil aviation and cardiology. Admission rules and follow-up of the technical flying personnel of TAP-Air Portugal].

The authors, based in European and American rules, consensus positions of Clinical Aerospace Congresses and their own experience, marked admission and follow-up rules of conduct for TAP Air Portugal aircrew. They stressed the importance of modern technology in arterial pressure ambulatory diagnosis and pointed the necessity of arterial pressure treatment in the other cardiovascular risk factors context. They relief ischemic myocardial disease because it is incompatible with flying safety, even in those submitted to coronary angioplasty or bypass graft surgery. For those with arrhythmias, valvular heart disease, myocarditis, cardiomyopathy and adult life congenital heart disease, we emphasize admission and follow-up rules.

Aerospace Medicine↗
PubMed1990

[Mitral prostheses with and without dysfunction: evaluation using 2-D Doppler echocardiography].

STUDY OBJECTIVE: To evaluate the flow characteristics of normal and abnormal functioning mechanical and bioprosthetic (B) mitral valves. DESIGN: Prospective study in patients submitted to mitral valve replacement. SETTING: Laboratory of Echocardiography at Santa Marta Hospital. PATIENTS: 61 consecutive and asymptomatic patients with normally functioning mitral prosthesis (prt)--37 Bjork-Shiley (B-S), 11 Carpentier-Edwards (C-E), 5 Hancok (HAN), 7 Ionescu-Shiley (I-S) and 1 Wessex--and 15 pts with abnormal prosthetic function (6 B-S, 5 Hall-Kaster, 2 C-E, 1 I-S and 1 HAN). INTERVENTION: Prosthetic mitral flow record, using 2D-Doppler echocardiography, to analyse: peak velocity (PV), peak gradient (PG), mean gradient (MG), pressure half time (PHT), area (A) and presence of regurgitation (R). RESULTS: Normally functioning prosthetic valves--PV ranged from 88 to 186 cm/s (134.6 +/- 24.3) in B-S prt and 133 to 198 cm/s (157.4 +/- 18.8) in B, p less than 0.0001. The prt B-S showed a greater PG (10.3 +/- 2.5 vs 7.6 +/- 2.6 mmHg), MG (3.1 +/- 1.1 vs 2.6 +/- 1 mmHg) and smaller area (2.3 +/- 0.4 vs 2.5 +/- 0.4 cm2) then Bioprosthetic ones, p less than 0.0001, p = 0.003, p = 0.003 respectively. There was a significant correlation between PG and MG: r = 0.84, r = 0.87, r = 0.84 respectively in B-S prt, Bioprosthesis and both, p less than 0.001. Mild regurgitation was present in 8 pts with prt B-S and 4 with B. Malfunctioning prosthetic valves--The mean of PV was 238.5 +/- 29.2 cm/s in prt B-S compared to 265.48.2 +/- 48.2 cm/s in B. Significant regurgitation, was detected by Doppler technic in 100% of B and 72% of mechanical prt. PV greater than 2 m/s has a 100% sensitivity and specificity to separate normal from abnormal prosthesis function. CONCLUSIONS: These data may be useful as reference values to the follow-up of pts with these types of prt. The prt B-S seems to have more optimal hemodynamics profile than B ones. Protodiastolic transprosthetic PV greater than 2 m/s suggest abnormal functioning valve. PG is a significant determinant of MG.

Adult↗
PubMed1989

[Flow patterns of a normally functioning monocuspid aortic prosthesis evaluated using Doppler echocardiography].

STUDY OBJECTIVE: Flow analysis in normally functioning eccentric monocuspid aortic prosthetic valves, to obtain a reference data list. DESIGN: To analyse, using 2D-Doppler Echocardiography, aortic flow velocity and systolic time intervals in clinically normal patients (pts), by physical examination. SETTING: Referred pts to the Echocardiographic Laboratory at Santa Marta Hospital--HCL. PATIENTS: Sequential sample of 61 pts with aortic prosthesis (41 Bjork-Shiley and 20 Hall-Kaster) without clinical evidence of either cardiac failure or significant aortic regurgitation. Patients with bad quality record were also excluded. INTERVENTIONS: Doppler Echocardiography was used to record transaortic flow, and the following indexes were analysed: instantaneous peak velocity (pv) and gradient (pg), presence of regurgitation, systolic time intervals and both preejection period/ejection time (PEP/ET) and acceleration time/ejection time (AT/ET). RESULTS: Pv ranged from 1.1 to 4 m/sec (mean 2.4 +/- 0.2. The prosthesis size 19 and 21 showed a greater pg compared to the larger ones: 46.3 +/- 14.4 mmHg against 12.6 +/- 6.4 mmHg (p less than 0.001). Occasionally a pg over 50 mmHg was found in the prosthesis size 19 and 21. The correlation between prosthesis size and pg was also significant (r = -0.62; p less than 0.001). PEP interval was 60 +/- 10 milisec in prosthesis no. 19 and 90 +/- 13 milisec in no. 27 (p less than 0.01). AT ranged from 77 +/- 14 to 88 +/- 14 milisec (mean 82 +/- 13). ET was 294 +/- 5.4 milisec in valves size 19 and 257 +/- 34 millisec in no. 25 (p less than 0.05); there was also a significant difference between prosthesis size 19 and 27 (p less than 0.05). Mild regurgitation was detected in 32.7% of cases. CONCLUSIONS: These data may be particularly useful as reference values to the follow-up of pts these types of prosthesis. Significant differences were found in pg between different valve sizes and this should be remembered when proceeding to standard evaluation by 2D-Doppler Echocardiography. Regurgitation is frequently detected in normally functioning prosthesis, not deeper than 2 cm in the left ventricle.

Adult↗
PubMedDate not supplied

P73 expression in neuroblastoma: a role in the biology of advanced tumors?

p73, a recently identified gene showing high homology to p53 and mapping to 1p36.33, was presented as a candidate gene for neuroblastoma. In this study the authors evaluate the levels and allelic nature of p73 expression in primary neuroblastomas using reverse transcription-polymerase chain reaction-restriction fragment length polymorphism strategies based on intragenic polymorphisms. From 32 neuroblastoma patients, 11 were heterozygous for the p73 polymorphisms analyzed. p73 expression was found to be low in the correspondent tumors and while all 6 stages 1 and 2 tumors presented biallelic expression, 4 out of the 5 stage 4 tumors showed only one active p73 allele. Analysis of blood samples from 8 healthy donors and 4 neuroblastoma patients revealed much higher levels of p73 expression, and exclusively of biallelic nature. These results are supportive of a role for p73 in the biology of neuroblastoma, particularly in some advanced tumors. Nevertheless, the G81A/C91T polymorphism, previously implicated in regulating the expression of p73, did not show any significant association with neuroblastoma development.

Adolescent↗
PubMedDate not supplied

Sex preselection in New York City: who chooses which sex and why.

With its increasing success, sex preselection has become a matter of general concern, and interest in it is growing. Three aspects of sex preselection in New York City were considered. Who is choosing the sex? Which sex is being chosen? Why have the choices been made? In this investigation, 178 couples were studied and all 57 non-American couples chose boys; however, 120 American couples chose boys and girls with equal frequency depending upon the gender of the children at home. Non-American couples chose boys for economic and business reasons (40%), cultural reasons (30%), and personal reasons (30%). Sex preselection is valuable in preventing sex-linked genetic disorders. Many are fearful of a sudden change in sex ratios should sex preselection be successfully and inexpensively carried out.

Cultural Diversity↗