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Biomedical subjects

A Gabriel

Publications and source records attributed to A Gabriel.

At least 109 records · Page 6Linked to original sources
PubMed1994

Image plate detectors for macromolecular neutron diffractometry.

Neutron diffraction studies of macromolecules require large position sensitive detectors. It is proposed that such a device can be based on image plate technology, which relies on re-usable photostimuable phosphors, combined with a neutron to gamma-ray converter. Design parameters such as the best wavelength for the neutron radiation and the optimum sample to detector distance are discussed, and a design for a cylindrical detector is outlined. Presently a prototype of such a detector is being built, and the very first test-recording of an X-ray diffraction pattern from a protein crystal is presented.

Journal Article↗
PubMed1994

[Selected elements of biological activity of circulating immune complexes in serum of patients with atopic diseases. I. Ability to injure guinea pig tissue by injecting atopic patient plasma].

Serum level was measured of circulating complexes (SpA binding method-CIC/SpA) in pollen and house dust mite sensitive patients during specific immunotherapy. Histopathological changes in guinea pigs skin after the intradermal injection of patients serum have been studied. Differences were demonstrated in the observed patho-morphological changes in relation to CICs/SpA serum concentrations.

Allergens↗
PubMed1993

Mice with a null mutation of the TGF alpha gene have abnormal skin architecture, wavy hair, and curly whiskers and often develop corneal inflammation.

Mice homozygous for a disrupted transforming growth factor alpha (TGF alpha) gene are healthy and fertile, although some older mice show evidence of corneal inflammation. In contrast with TGF alpha +/- and +/+ animals, TGF alpha -/- mice have a pronounced waviness of the coat. Histological examination of the skin from TGF alpha -/- mice reveals a dramatic derangement of hair follicles. Mice with a disrupted TGF alpha gene also have curly whiskers, first evident on the day of birth. The phenotype of TGF alpha -/- mice is remarkably similar to that of the mouse mutant waved-1 (wa-1). Offspring resulting from crosses between TGF alpha -/- and wa-1 mice display the curly whisker-coat phenotype, indicating that the basis of the wa-1 phenotype is a mutation in the TGF alpha gene. These observations suggest that TGF alpha plays a pivotal role in determining skin architecture and in regulating hair development.

Animals↗
PubMed1993

Improved cardiac performance and reduced pulmonary vascular constriction by epinephrine administration via a left atrial catheter in cardiac surgical patients.

Diminished left ventricular contractility and increased right ventricular afterload are issues in cardiac surgery. The usual administration of catecholamines (epinephrine) via the central venous (CV) catheter increases cardiac output, but also may increase pulmonary vascular constriction. Epinephrine was, therefore, administered via the left atrial (LA) catheter or the CV catheter in 8 cardiac surgery patients, each serving as his or her own control. The LA administration of epinephrine has an advantage with its immediate effect on the coronary circulation, while avoiding associated pulmonary vasoconstriction by passing through the systemic capillary bed before reaching the lung. It was found in this study that administration of epinephrine via an LA catheter increased the average cardiac output by 1.05 L/min, which was significantly (P < 0.05) greater than with administration via the CV catheter. With LA administration of epinephrine, systemic arterial pressure (systolic arterial pressure and diastolic arterial pressure) (SAP, DAP) were also elevated to a greater extent than by CV administration. On the other hand, pulmonary arterial pressures (systolic pulmonary arterial pressure and diastolic pulmonary arterial pressure) (SPAP, DPAP) were less elevated than by administration via the CV catheter. This produced increased coronary perfusion and a smaller increase in pulmonary vascular tone by LA administration in contrast to CV administration of epinephrine. It is concluded that epinephrine administration via an LA catheter improved myocardial performance and pulmonary perfusion due to direct entry of the agent into the coronary circulation and partial metabolism while passing through the systemic capillary bed before reaching the lung.

Blood Pressure↗
PubMed1993

The gene for C10, a member of the beta-chemokine family, is located on mouse chromosome 11 and contains a novel second exon not found in other chemokines.

C10 is a recently described member of the beta-chemokine subfamily of the chemokine superfamily of cytokine proteins. Genomic clones encoding murine C10 were isolated and sequenced. The other members of the beta-chemokine family have a three-exon genomic structure containing, among other sequence similarities, four cysteines spaced in a highly conserved manner. In each of these genes, the second exon contains the first three of the four conserved cysteines, and the third exon contains the last. In contrast to this genomic structure, the C10 gene has four exons, with a novel second exon of 48 nucleotides. Exons 3 and 4 of C10 contain four cysteines distributed in the same manner as in exons 2 and 3 of other beta-chemokine family members. The novel second exon codes for a large number of charged amino acids, and this exon shows no homology to any previously described sequences in computer databases. Linkage studies showed that the C10 gene (Scya6) is closely linked to the Scya2 locus on mouse chromosome 11, indicating that the C10 gene is located in the same region of mouse chromosome 11 as other members of the beta-chemokine family. Thus, although the C10 gene contains a novel exon not found in any other members of the chemokine superfamily, its chromosomal location and conservation of cysteine residues and other structural features suggest that it evolved from the same ancestral gene as other members of the beta-chemokine family.

Amino Acid Sequence↗
PubMed1992

Transplantation of fetal mouse colon under the kidney capsule of an adult mouse: a model for the study of colonic development.

Fourteen-day fetal mouse colon was transplanted under the kidney capsule of an adult mouse to determine whether this system could be used as a model of embryonic colonic development. The 14-day fetal colon was transplanted and left for a period of 7 days. Comparisons of the normal one day postnatal colon and the transplanted colon were made morphologically and morphometrically. It was found that the transplanted fetal colon resembled its postnatal counterpart with respect to morphology; the cell types seen in the transplanted colon were similar to those observed in the in situ colon of the same age. However, morphometric analysis showed that the transplanted colon was significantly smaller than its postnatal counterpart, suggesting that conditions in the host were not optimal to support the full growth of the colon. In spite of this, it appears that the fetal colon can differentiate normally under the kidney capsule and this model can be used to study both epithelial-mesenchymal interactions and the role of hormones in fetal colonic development.

Animals↗
PubMed1992

Non-invasive vs. invasive beat-to-beat monitoring of blood pressure.

The present study focuses on the accuracy in tracing fast beat-to-beat changes in blood pressure using a non-invasive technique. The measurements using a commercially available apparatus (Finapres, Ohmeda, USA) were compared to ipsilateral intra-arterial radial pressure. Eight patients were studied at rest, during deep breathing with a fixed rate of 6 breaths min-1, and during an exercise test on an ergometer cycle. A total of 900 systolic pressure values were included for statistical evaluation, covering a pressure range of 86-266 mmHg. On average the systolic correlation coefficient for the whole material was 0.97, with a range of 0.94-0.996. For mean pressure the correlation coefficient was on average 0.97, and for diastolic pressure 0.93. No systematic difference between the non-invasive and the invasive method was found, although for each individual patient a difference between direct and indirect measured blood pressure existed that could be relatively large (systolic pressure: average difference = 0.8 mmHg, SD = 16 mmHg). We found the method easy to handle and consider it excellently suited to track relative changes in blood pressure.

Aged↗
PubMed1992

[The role of antiglobulin antibodies in pathophysiology of various internal diseases].

Antiglobulins are a heterogenous group of antibodies specific for a large number of antigenic determinants on the heavy chains of various classes and on light chains. They are capable of reacting with hidden antigenic determinants of gamma globulins after they have been exposed by the action of proteolytic enzymes or after antigen-antibody reaction during which changes occur in the spatial configuration of the Fc fragments of immunoglobulin causing that they assume immunogenic properties. Antiglobulin antibodies against episomes in the Pab fragment of other antibodies have a strong regulatory influence on the immune response in view of their ability of specific interference with the response to a specific antigen. Antiglobulin antibodies may exert a protective effect but also a pathogenic effect. The latter has been demonstrated in atopic diseases, in IgA glomerulonephritis, in rheumatoid arthritis, in infectious mononucleosis, cryoglobulinaemia, in patients with IgA deficiency associated with presence of antiglobulin antibodies to IgA after transfusion of plasma or intravenous infusion of gamma globulins containing IgA.

Antibodies, Anti-Idiotypic↗
PubMed1991

Reverse transcriptase encoded by a human transposable element.

L1 elements are highly repeated mammalian DNA sequences whose structure suggests dispersal by retrotransposition. A consensus L1 element encodes a protein with sequence similarity to known reverse transcriptases. The second open reading frame from the human L1 element L1.2A was expressed as a fusion protein targeted to Ty1 virus-like particles in Saccharomyces cerevisiae and shown to have reverse transcriptase activity. This activity was eliminated by a missense mutation in the highly conserved amino acid motif Y/F-X-D-D. Thus, L1 represents a potential source of the reverse transcriptase activity necessary for dispersion of the many classes of mammalian retroelements.

Base Sequence↗
PubMed1991

Reverse transcriptase encoded by a retrotransposon from the trypanosomatid Crithidia fasciculata.

The long interspersed nuclear element (LINE)-like elements are a distinct family of eukaryotic transposons that contain a long open reading frame with limited sequence homology to retroviral reverse transcriptases. Unlike many retrotransposons, they lack long terminal repeats. The mechanism by which LINE-like elements move within the genomes of their hosts remains speculative. We have used an unusual approach to express and detect enzymatic activities associated with Crithidia retrotransposable element 1 (CRE1), a site-specific LINE-like element found in the insect trypanosomatid Crithidia fasciculata. A chimeric gene fusing the yeast retrotransposon Ty1 and the CRE1 open reading frame is constructed and then overexpressed in yeast. Fusion proteins are packaged into virus-like particles, which can be partially purified and directly analyzed for enzymatic activity. Here we demonstrate that CRE1 encodes an RNA-directed DNA polymerase. These data provide direct biochemical evidence that this widely distributed class of retrotransposons encodes reverse transcriptase and sets the stage for a detailed understanding of the mechanisms involved in LINE-like element transposition.

Animals↗