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Biomedical subjects

M García

Publications and source records attributed to M García.

At least 289 records · Page 16Linked to original sources
PubMed1990

Regulation, clinical and biological significance of cathepsin D in breast cancer.

The lysosomal protease, pro-cathepsin D, is overexpressed and secreted by human breast cancers. In estrogen-responsive breast cancer cell lines, estrogens and growth factors stimulate cathepsin D expression through distinct mechanisms. Clinical studies indicate that high cathepsin D concentration in primary breast cancers is correlated with an increased risk of metastasis and particularly useful to orientate node-negative tumors towards an adjuvant therapy.

Breast Neoplasms↗
PubMed1990

Kerosene-induced asthma.

Clinical evaluation of 286 asthmatic women showed 15.5% of those who improved clinically had contact with kerosene, while 43.9% of those who failed to improve used kerosene as fuel for cooking. In 16 women the onset of asthma occurred soon after they began to use kerosene. Kerosene can cause and aggravate asthma.

Asthma↗
PubMed1990

[Transfusion management of a patient with multiple anti-erythrocyte antibodies (anti-c + anti-K + anti-Fyb + anti-Jkb) subjected to a valvular reoperation using extracorporeal circulation].

A woman with multiple anti-red cell antibodies (anti-c, anti-K, anti-Jkb, anti-Fyb) due to previous transfusions was admitted to the hospital for valvular replacement. To ensure enough transfusional supply, a high number of packed red cell units was typed and screened prior to previous operation. Haemorrhagic complications developing during surgery led to transfusion of 32 blood units, 20 of them compatible. Besides this, measures directed to prevent complications derived from haemolytic disease were instituted. These included intravenous fluids and diuretics to maintain circulatory integrity and improve renal cortical blood flow. High-dose gammaglobulin was also administered in an attempt to decrease extravascular haemolysis. Despite therapy, severe adult distress respiratory syndrome caused patient's death nine days after surgery. We remark the need of storing frozen blood of low-frequency phenotypes in blood banks to face significant transfusional problems, providing sufficient numbers of antibody-compatible blood.

Agglutinins↗
PubMed1989

Human papillomavirus infection and cervical cancer in Latin America.

To evaluate a possible association between infection with human papillomavirus (HPV) and cervical cancer, we performed a multicenter case-control study in Latin America of 759 cases of invasive cervical cancer and 1467 randomly selected age-matched controls. Demographic, sexual, behavioral, and other clinical data were obtained by interview, and HPV DNA was assayed in cervical-swab specimens with use of filter in situ hybridization. Cervical infection with HPV 16 or 18 or both was strongly associated with cervical cancer. HPV DNA was detected in 62 percent of the cases but only 32 percent of the controls, and the relative risk of cancer increased from 2.1 (95 percent confidence interval, 1.6 to 2.8) to 9.1 (6.1 to 13.6) with hybridization reactions of increasing strength. Although the number of sexual partners, age at first intercourse, number of live births, and Pap-smear history were also significant risk factors, the strong associations between infection with HPV 16 or 18 or both and cervical cancer persisted after we adjusted for these variables. These observations are consistent with the hypothesis that genital infection with HPV 16 or 18 may have a role in the pathogenesis of cervical cancer. Other well-known risk factors were also identified in the study, but they did not affect the association between HPV and cervical cancer.

Adult↗
PubMed1989

Nucleolar structures in chromosome and SC preparations from human oocytes at first meiotic prophase.

We describe a comparative study of the behavior of nucleolar structures and their relationship with nucleolar chromosomes and synaptonemal complexes at first meiotic prophase of human oocytes in an attempt to elucidate the nature of this cellular organization and to learn more about maternal nondisjunction. The number of main nucleoli varies along the different stages of prophase I and is usually low. It shows an increase from leptotene to pachytene and a decrease from pachytene to diplotene related to a decrease and an increase of main nucleoli volume, respectively. The methodology employed has enabled us to analyze in detail dark bodies, round bodies, dense bodies, and main nucleoli in chromosome or synaptonemal complex spreads. The relationship between nucleolar chromosomes or synaptonemal complexes and the nucleoli implies the existence, in a very reduced space, of chromosomal regions that contain homologous sequences and that are often unpaired. This situation may facilitate the production of heterologous pairing and chromosomal exchanges between nonhomologous chromosomes and finally result in aneuploidy. Thus, the situation explained above together with the differences between the oocyte and spermatocyte NOR cycles could be one of the reasons for the higher incidence of aneuploidies of maternal origin at meiosis I.

Cell Nucleolus↗
PubMed1989

Mitochondrial cytochrome b genes with a six-nucleotide deletion or single-nucleotide substitutions confer resistance to antimycin A in the yeast Kluyveromyces lactis.

Extrachromosomal mutants resistant to antimycin, from the yeast Kluyveromyces lactis, have been isolated, genetically characterized, and assigned to two specific genetic loci (Brunner et al., 1987). In the present work the cytochrome b nucleotide sequence from six of these mutants was determined. Five mutants had single point mutations, corresponding to transversions. In one mutant, a six-base-pair deletion, beginning at nucleotide 689, was observed. The amino acid sequence derived from the coding strand showed that, in three independent antimycin-resistant mutants, a change of asparagine 31 into lysine took place (two of these mutants are also resistant to diuron). Two other mutants showed a change from lysine 228 into isoleucine (or methionine). Leucine 230, isoleucine 231, and threonine 232, were lost in the deletion mutant and were replaced by serine.

Amino Acid Sequence↗
PubMed1989

[Recurrent thrombotic thrombocytopenic purpura and pregnancy].

Two women are presented who were diagnosed of thrombotic thrombocytopenic purpura (TTP) during their first pregnancies, leading in both cases to spontaneous abortion. Both patients improved after plasma exchange or fresh plasma infusion. Two new pregnancies on each patient, closely watched on gynaecological and haematological grounds, led to TTP reactivation. Obstetrical and haematological management was similar for the two women (fresh-frozen plasma administration) but it yielded different results, since, although the risks for the mothers were controlled, one of the patients gave birth successfully on two occasions while the other developed stillborns on two occasions as well. These observations suggest the inter-relationship between TTP and pregnancy, and point to some pathophysiological aspects of the foetal deth repeteadly presented by one of the patients. A review of the literature is presented on the basis of these cases of PTT associated to pregnancy.

Adult↗
PubMed1989

AIDS in Colombia.

Between January 1984 and December 1987 a total of 178 AIDS cases were reported to the Colombian Ministry of Health. The location of these cases suggests that the human immunodeficiency virus (HIV) is widely distributed in Colombia. Most of those afflicted (97%) have been adult males. HIV seroprevalence studies of selected population groups revealed the highest antibody prevalence (5.65% in females, 22.5% in males) among individuals involved in high-risk behaviors who participated in a free AIDS testing program. High prevalences (from 0.6% to 3.9% in females, and 14.6% to 15.9% in males) were also found in patients (primarily female prostitutes and male homosexuals) attending clinics for sexually transmitted diseases in several urban areas. The number of AIDS cases in Colombia has doubled or tripled annually since reporting began in 1984, a pattern similar to that observed worldwide.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Kinetic study of the transient phase of a chemical reaction system coupled to an enzymatically catalyzed step. Application to the oxidation of epinine by tyrosinase.

The present work deals with epinine oxidation by mushroom tyrosinase and sodium metaperiodate. Intermediates produced within short reaction times were characterized by repetitive scanning spectrophotometry and the stoichiometry of the appearance of the respective aminochrome was established. The oxidation pathway from epinine to aminochrome had the following steps: epinine----o-quinone-H+----o-quinone----leukoaminochrome----aminoc hrome. The stoichiometry for the conversion of o-quinone-H+ into the aminochrome of epinine followed the equation: 2 o-quinone-H+----epinine+aminochrome. A transient phase kinetic study has been developed for the system of chemical reactions coupled to an enzymatically catalyzed step, these taking place when epinine is oxidized by mushroom tyrosinase. Rate constants for the implied chemical steps at different temperature and pH values were calculated from analysis of the progress curves of aminochrome accumulation with time. The thermodynamic activation parameters of the chemical steps were also calculated.

Basidiomycota↗