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Biomedical subjects

A Carrera

Publications and source records attributed to A Carrera.

10 recordsLinked to original sources
PubMed1992

Thymic selection.

The ability of T cells to recognize foreign antigens, distinguish them from self antigens, and regulate immune responses depends largely on which of the vast array of different T-cell receptors they display on their surface, the so called T-cell repertoire. Two selection processes, positive and negative selection, operate on developing T cells and allow only a subset of all possible T cells to differentiate. New developments in transgenic mouse technology and the study of T-cell signalling are unravelling these fascinating processes.

Animals↗
PubMed1991

Purification and initial characterization of the lymphoid-cell protein-tyrosine kinase p56lck from a baculovirus expression system.

The lymphocyte-specific protein-tyrosine kinase p56lck has been purified 90-fold to approximately 30% purity in 30% yield from a baculovirus expression system by a two-column purification procedure. At least two forms of p56lck were isolated, differing in the extent of phosphorylation and migrating as 56- and 59-kDa species on SDS/PAGE but as a single 56-kDa band after treatment with potato acid phosphatase. Autophosphorylation of purified p56lck occurred at a rate of 25 fmol/min to a maximum incorporation of approximately 2 mol of phosphate per mol of p56lck with tyrosine-394 (but not tyrosine-505) and other, unidentified tyrosine residue(s) being the major sites of phosphorylation in vitro. Phosphorylation of tyrosine-containing peptides was monitored using an automated HPLC system. Although peptide substrate Km values were in the 1-5 mM range, the Vmax for the 13-amino acid peptide RRLIEDAEYAARG (modified p60src autophosphorylation site) was 120 min-1 (350 min-1 when adjusted for p56lck purity), suggesting that the enzyme purified from recombinant baculovirus-infected Sf9 cells has a high catalytic turnover compared with other tyrosine kinases.

Amino Acid Sequence↗
PubMed1990

[Effect of smoking on hematologic parameters in healthy people].

In a cross-sectional study we investigated the effect of smoking on hematological parameters in 507 apparently healthy individuals. A positive association was found between smoking and leukocyte count, hemoglobin concentration, packed red cell volume, mean corpuscular volume, and mean corpuscular hemoglobin. By contrast, erythrocyte sedimentation rate was significantly lower in smokers. The number of red blood cells and mean corpuscular hemoglobin concentration were not associated with smoking. When health examinations are carried out, and whenever laboratory studies of healthy or ill persons are evaluated, the effect of smoking on hematological parameters should be considered.

Adult↗
PubMed1986

Active defence of retinal temperature during hypothermia of the eye in cats.

The first objective was to determine how large changes in externally applied cooling influence intraocular temperature. The second objective was to determine whether vasoactive changes in the choroidal circulation influence retinal temperature. Temperature in the conjunctiva was decreased down to 6 degrees C by direct cooling of the cat's eye and the temperatures along the visual axis were measured with thermocouple probes. Temperature in the retina was maintained fairly constant showing thus an active resistance to cooling of the eye, but temperatures in the anterior chamber and lens were dependent on external temperature changes. Administration of vasoconstrictor drugs in the retrobulbar space resulted in drop of retinal temperature presumably by reducing choroidal blood flow during eye cooling. The experiments showed that the eye is provided with vasoactive mechanisms that allow temperature preservation in critical areas, such as the retina, even in the presence of extreme temperature changes. However, other ocular regions show passive resistance to cooling of the eye.

Animals↗
PubMed1975

Glucose phosphate isomerase deficiency with hereditary hemolytic anemia in a Spanish family: clinical and familial studies.

A new case of glucose phosphate isomerase deficiency associated with cogenital nonspherocytic hemolytic anemia is described in a 12-year-old girl of Spanish origin. The parents exhibited erythrocyte glucose phosphate isomerase activity between 50 and 60% of normal. The enzyme of the propositus had normal Michaelis-Menten constants both for F-6-P and G-6-P, but abnormal pH optimum and decreased heat stability at 48 degrees C. On starch-gel electrophoresis the father's enzyme was normal but the mother's showed a cathodic migrating band in addition to the normal one. The enzyme from the propositus exhibited only one band with cathodal mobility of 116% of the main band found in normal subjects. It is postulated that the propositus is double heterozygous for two abnormal alleles, and the mother contributes a mutant allele with abnormal electrophoretic mobility and thermolability at 48 degrees C whereas the father contributes an allele without enzymatic activity.

Alleles↗