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Biomedical subjects

L Lopes

Publications and source records attributed to L Lopes.

35 records · Page 2Linked to original sources
PubMed1998

Enhanced human cell engraftment in mice deficient in RAG2 and the common cytokine receptor gamma chain.

Xenotransplantation of human cells into immunodeficient mice has been used to develop models of human haemopoiesis and lymphoid cell function. However, the utility of existing mouse strains can be limited by shortened life-spans, spontaneous production of functional lymphocytes with ageing, and residual innate immunity leading to variable levels of engraftment. Mice with a deletion of the common cytokine receptor gamma chain (gamma c) gene have reduced numbers of peripheral T and B lymphocytes, and absent natural killer cell (NK) activity. A genetic cross with a recombinase activating gene 2 (RAG2)-deficient strain produced mice doubly homozygous for the gamma c and RAG2 null alleles (gamma c-/RAG2-). These mice have a stable phenotype characterized by the absence of all T lymphocyte. B lymphocyte and NK cell function. Injection of human B-lymphoblastoid cells resulted in earlier fatal metastatic lymphoproliferative disease than in NOD/LtSz-scid controls. This was particularly evident in animals injected intravenously, possibly because of residual NK activity in NOD/LtSz-scid mice. Levels of engraftment with peripheral-blood-derived human lymphocytes were also increased and associated with higher CD4/CD8 ratios. These findings demonstrate that this new strain of immunodeficient mice has significant advantages over existing strains for engraftment of human cells, and may be useful for study of adoptive immunotherapy and novel therapies for GvHD and HIV infection.

Animals↗
PubMed1997

[Blood pressure normal values in children and adolescents according to age and height].

The assessment of blood pressure in children and adolescents is of great importance in order to gain a better understanding of its pattern of evolution. The authors publish the normal values of blood pressure in Portuguese children and adolescents, according to age and sex, as well as the mean values of the 90th percentile, which are very important to separate normal children from those with high blood pressure. In this study the fifth Korotkoof sound is used to define diastolic blood pressure in all ages. New blood pressure tables are also published, for children and adolescents, that now include the height percentile for age and blood pressure. These new charts have been developed to guide practising clinicians in antihypertensive drug therapy, when indicated.

Adolescent↗
PubMed1997

[Blood pressure in a population of youngsters and adults observed after 17 years].

Many studies have assessed the blood pressure tracking among children and adolescents, but the results have been controversial. This study assessed the blood pressure tracking in 224 Portuguese school children and young adults following them for 17 years. The correlations obtained for systolic and diastolic blood pressure in both sexes are not very high, although positive and statistically significant. On the other hand, there was a stronger correlation between anthropometric variables and blood pressure and indices of obesity.

Adolescent↗
PubMed1997

Effects of a self-etching primer on enamel shear bond strengths and SEM morphology.

PURPOSE: To study a dental adhesive system containing a self-etching primer, by evaluating the enamel shear bond strengths and comparing the SEM interfacial morphology. MATERIALS AND METHODS: 100 flat enamel bonding sites were prepared to 600-grit on proximal surfaces of caries-free human molars. The bonding surfaces were treated with Clearfil Liner Bond 2 as recommended by the manufacturer, or combined with various acidic etchants. A composite rod (Clearfil Photo Anterior) was applied to the bonding area in two increments in a Teflon mold and polymerized for 100 s. After 24 h of water storage, the specimens were thermocycled and the shear bond strengths measured using an Instron testing machine. Forty extra molar crowns were roughened and treated with Clearfil Liner Bond 2 and alternative etchants, as described. A low-viscosity resin was bonded to the occlusal surfaces of these crowns, which were further demineralized and deproteinized. Field-Emission SEM examinations were carried out to evaluate the effects of different treatments on enamel surfaces. RESULTS: The mean shear bond strengths were in the range of 18.1 MPa to 25.9 MPa, without significant differences between pairs of means. The failures were predominantly of the adhesive type. The use of alternative etchants resulted in the deepest etching patterns. The use of Clearfil Liner Bond 2, according to manufacturer's directions, resulted in a poorly-defined etching pattern. Regardless of the alternative etchant used, the use of the self-etching primer did not affect the mean enamel shear bond strength.

Acid Etching, Dental↗
PubMed1995

Prenatal diagnosis of GM2-gangliosidosis B1 variant.

Prenatal diagnosis in a pregnancy at risk for a juvenile B1 variant of GM2-gangliosidosis was carried out. The biochemical study of the cultured amniocytes and the affected fetal brain is reported. The results obtained show that the sulphated artificial substrate can be used in the diagnosis of B1 variant, but not the neutral one. The accumulation of GM2-ganglioside in the fetal brain of the B1 juvenile form and an infantile form of GM2-gangliosidosis (0 variant) was compared.

Amniocentesis↗
PubMed1995

Towards the development of a fluorescent in situ hybridization based genotoxicologic assay for aneuploidy detection in sperm.

Fluorescent in situ hybridization (FISH) is a molecular cytogenetic technique which allows an analysis of chromosome copy number in interphase cells. The cytological examination of spermatozoa is routinely performed as part of semen analysis. While this analysis is only a component of the evaluation of an infertile male, the aetiology of many cases of infertility remains unknown. FISH on semen smears can yield information on chromosome-specific aneuploidy due to constitutional and acquired chromosomal abnormalities as found with cancer or exposure to genotoxic substances. The ability to analyse germ cells directly is a useful adjunct to GTG-banding analysis of meiotic chromosomes, an invasive and extremely labour-intensive procedure. The work of 2 years in developing and optimizing a FISH-based assay in routinely processed semen smears is described.

Aneuploidy↗
PubMed1994

Influence of the method of purification on some solution properties of welan gum.

The origin and some consequences of the presence of aggregates and impurities (deriving from the fermentation procedure) on the solution properties of welan gum have been studied. For this purpose, a method of purification was developed for a fermentation welan broth. It was verified that this method is ineffective for the dissociation of aggregates in the commercial product. This demonstrates the irreversible nature of the intermolecular interactions of welan samples isolated by precipitation in the presence of impurities. The purified products were characterized (Mw, [eta], kH) and the results were compared to those obtained from commercial samples of welan. The influence of the method of purification on the rheological properties was analysed.

Carbohydrate Conformation↗
PubMed1994

Perinatal outcomes of a large cohort of extremely low gestational age infants (twenty-three to twenty-eight completed weeks of gestation).

OBJECTIVES: To determine gestational age (GA)-specific mortality rates; the effects of GA, birth weight, sex, and multiple gestation on mortality rates; short-term morbidity for infants born at 23 to 28 weeks GA; and impairment rates at a corrected chronologic age of 18 months for those born at 23 to 25 weeks GA. METHODS: A data base analysis was performed with a linked obstetric and a neonatal database. GA was determined by obstetric data and confirmed by early ultrasonography (available in 88%) on all births < 30 weeks GA at British Columbia's tertiary perinatal center from 1983 to 1989. RESULTS: Of 1024 births occurring between 23 and 28 weeks GA, 911 were live born. The mortality rate decreased with increasing GA: 84% at 23 weeks; 57% at 24 weeks; 45% at 25 weeks; 37% at 26 weeks; 23% at 27 weeks; and 13% at 28 weeks GA. For each GA, mortality rate versus birth weight plots showed a decreasing mortality rate with increasing birth weight, except for infants who were large for GA. Male infants had a higher mortality rate than female infants (odds ratio, 1.8; confidence interval, 1.4 to 2.5). Twins fared worse than singletons with a decreasing effect from 24 weeks GA (odds ratio, 10.3) to no effect at 28 weeks GA. The median number of days supported by mechanical ventilation and the length of stay in the neonatal intensive care unit decreased markedly with increasing GA. Eighteen-month outcome of survivors between 23 and 25 weeks GA with 93% follow-up rate revealed an overall impairment rate of 36%, but 6 of the 9 surviving 23-week infants had major impairments. CONCLUSIONS: The GA-specific perinatal outcome results of this large cohort provide information to assist in perinatal management decision making and for counseling parents prenatally.

Adolescent↗
PubMed1994

A unified approach to the design of clinical reporting systems.

Computer-based Clinical Reporting Systems (CRS) for diagnostic departments that use structured data entry have a number of functional and structural affinities suggesting that a common software architecture for CRS may be defined. Such an architecture should allow easy expandability and reusability of a CRS. We report the development methodology and the architecture of SISCOPE, a CRS originally designed for gastrointestinal endoscopy that is expandable and reusable. Its main components are a patient database, a knowledge base, a reports base, and screen and reporting engines. The knowledge base contains the description of the controlled vocabulary and all the information necessary to control the menu system, and is easily accessed and modified with a conventional text editor. The structure of the controlled vocabulary is formally presented as an entity-relationship diagram. The screen engine drives a dynamic user interface and the reporting engine automatically creates a medical report; both engines operate by following a set of rules and the information contained in the knowledge base. Clinical experience has shown this architecture to be highly flexible and to allow frequent modifications of both the vocabulary and the menu system. This structure provided increased collaboration among development teams, insulating the domain expert from the details of the database, and enabling him to modify the system as necessary and to test the changes immediately. The system has also been reused in several different domains.

Artificial Intelligence↗
PubMed1993

The correlation between round cells and white blood cells in the semen.

It is generally recognized that white blood cells in semen are detrimental to sperm function and fertility. Traditionally, pyospermia has been suspected if greater than 10 round cells per high power field or more than 1 million round cells per ml. were identified in the semen. Since immature germ cells and white blood cells appear as round cells under wet mount light microscopy, the relationship between increased numbers of round cells in semen and true pyospermia was examined. Semen analyses were performed on specimens from 627 infertility patients. The numbers of round cells per high power field and the number of round cells per ml. of semen were recorded. Specimens from 57 patients (9%) persistently demonstrated greater than 10 round cells per high power field or more than 1 million round cells per ml. and they were subjected to immunohistochemical staining against white blood cell surface antigens. Greater than 1 million white blood cells per ml. were identified in only 20 patients (35%) and only 8 samples demonstrated more than 3 million white blood cells per ml. Of the patients with greater than 1 million white blood cells per ml. 65% had motilities of less than 60% compared to 49% of the patients with less than this amount of pyospermia. This difference was not statistically significant. Round cells counted on a per milliliter basis correlated better with results of immunohistochemical staining than did round cells counted on a per high power field basis. These data demonstrate that the majority of patients with excess round cells in the semen do not have pyospermia and, therefore, empiric antibiotic therapy without further testing will likely be unproductive.

Humans↗
PubMed1993

Formal representation of a conceptual data model for the patient-based medical record.

We present a general architecture for the patient-based medical record as it is being developed for the SAMS, a private social security system. The conceptual data model is described in a convenient formal notation, the entity-relationship diagram. Although following the original formulation of the problem-oriented medical record (POMR), the data model was designed with a level of generalization that, functionally, makes structural differences between conventional and POMR no longer apparent. The main features of this model are its adaptability to individual work practices and its problem-oriented structure, including the representation of problems' evolution. This structure will enable physicians to organize the data, mostly collected elsewhere, by explicitly relating the facts that constitute a particular patient record, which is a simple way to store context information and clinical knowledge that is not part of patient data.

Database Management Systems↗
PubMed1989

[Methods for preparing and preserving skin allografts from live donors following the operation].

Three methods of processing allografts from live donors after plastic operations when excess skin remains are presented. Such possibilities arise in reducing mammaplasty and venter propendens. Processing takes place with a device, constructed by the authors, and with apparatus for dermatome treatment of skin in decolman, introduced by I. Chervenkov et al. Processed skin allografts is stored for short-term usage at +4 degrees C or at -30 degrees C for six months.

Equipment Design↗
PubMed1986

The impact of a drug information sheet on the understanding and attitude of patients about drugs.

A proposed Food and Drug Administration program to require written information with prescription drugs could cost $500 million annually; the American Medical Association has implemented a similar, voluntary program costing more than $3 million. However, the educational impact of written drug information has not been studied. We evaluated one-page drug information sheets using an objective examination. The baseline score of 71 patients was 3.9 of 6.0. Patients tested before and one day after receiving the drug sheet improved their score by +1.4. In the second phase, patients randomized to receive the drug sheet improved their score after one month by +1.1; those not given the sheet had no improvement. Changes in attitudes and incidence of reported adverse effects seemed to be random and unrelated to the information sheet. Thus, a drug information sheet may be a useful adjunct to patient education.

Attitude↗