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Biomedical subjects

J Sanchez

Publications and source records attributed to J Sanchez.

At least 109 records · Page 6Linked to original sources
PubMed1995

A novel exocytoplasmic endonuclease from Streptomyces antibioticus.

A new exocytoplasmic, nutritionally controlled endodeoxyribonuclease (EC 3.1.21.-) was purified to homogeneity from Streptomyces antibioticus. The enzyme showed an apparent molecular mass of 29 kDa (being active in the monomeric form) and a pI of approximately 7.8. The nuclease hydrolysed endonucleolytically double-stranded circular and linear DNA. The enzyme makes nicks in one strand of the DNA in G-rich regions, leaving either 5' or 3' short, single-stranded overhangs with 3'-hydroxy and 5'-phosphate termini. Breaks in the DNA occur when two nicks in opposite strands are close together. The enzyme had an optimum pH of 7.5 and an absolute requirement for bivalent cations and > or = 100 mM NaCl in the reaction buffer. Activity was greatly diminished in the presence of phosphate, Hg2+ or iodoacetate and was stimulated by dimethyl sulphoxide. Single-stranded DNA was a much poorer substrate than double-stranded DNA. The nuclease hydrolyses sequences of three or preferably more (dG).(dC) tracts in the DNA. The initial specificity shifts to other sequences (including sequences shorter than those initially hydrolysed) during the course of the reaction, giving the changing pattern of bands observed in agarose gels. 5-Methylcytosine-hemimethylated DNA is not hydrolysed by the nuclease. The properties of this novel enzyme suggest a relationship with class II restriction endonucleases and also with some eukaryotic nucleases.

Base Sequence↗
PubMed1995

Control of contact activation on end-point immobilized heparin: the role of antithrombin and the specific antithrombin-binding sequence.

The uptake and activation of FXII from blood plasma was studied in small-diameter polyethylene tubing, surface-modified by end-point immobilization of heparin. Two preparations of heparin were used to modify the contact-activating properties of the plastic tubing: unfractionated, functionally active heparin and low-affinity heparin, lacking the specific antithrombin-binding sequence and virtually devoid of anticoagulant activity. The uptakes of FXII on the two heparin surfaces were similar. No activated FXII could be demonstrated on the unfractionated heparin surface, whereas on the low-affinity heparin surface nearly all FXII underwent spontaneous activation. The suppression of FXII activation on the unfractionated heparin surface was investigated by using plasma depleted of antithrombin, complement C1 esterase inhibitor, or both. The removal of antithrombin resulted in extensive activation of FXII, whereas the depletion of C1 esterase inhibitor had only a minor effect. Experiments with recalcified plasma showed rapid clot formation during exposure to the low-affinity heparin surface. After depletion of antithrombin, but not complement C1 esterase inhibitor, the recalcified plasma clotted in contact with the unfractionated heparin surface as well. We conclude that antithrombin and the antithrombin-binding sequence in the surface-immobilized heparin are essential for the prevention of surface activation of FXII and triggering of the intrinsic coagulation system.

Animals↗
PubMed1995

Time trends in acute childhood asthma in Basque Country, Spain.

To investigate recent changes in the epidemiology of acute asthma in children in a hospital setting, data from the Basque region of Bizkaia, Spain were reviewed for the period between 1987 and 1992. Over this period there was a 18% drop in hospital emergency visits for asthma in children aged 2-14 years from 1,697/100,000 to 1,382/100,000. It was associated with a decline in the number of annual episodes per patient and in the number of patients needing further hospital treatment for the same episode. Paradoxically, hospital admission rates rose by 35.9% from 298/100,000 to 405/100,000. A trend toward decreasing length of hospital stay, a fall in the number of intensive care unit admissions, and an absence of in-hospital deaths were observed. Comparing data from September 1987 with those of September 1992, a trend has been noticed toward greater intensity of emergency room treatment with increases in the number of doses of nebulized beta 2-agonists administered and in courses of oral prednisolone given. In September 1992 more patients were on maintenance "anti-inflammatory" inhaled therapy than in 1987.

Acute Disease↗
PubMed1995

Optimal timing of granulocyte colony-stimulating factor (G-CSF) administration after bone marrow transplantation. A prospective randomized study.

The positive role of G-CSF in hastening the myeloid recovery of patients undergoing allogeneic bone marrow transplantation (ALLO-BMT) or autologous bone marrow transplantation (ABMT) has recently been established. Considerable knowledge about adequate doses and route of administration has been accumulated in the past few years. Nonetheless, the optimal time to start growth-factor administration remains undetermined. We have performed a stratified study according to the source of hematopoietic progenitors (ALLO-BMT or ABMT), underlying disease and its stage, and acute graft-versus-host disease (GVHD) prophylaxis regimen and randomized patients in two arms: group A, which started G-CSF on day 0 (36 patients), and group B, which started on day +7 post-BMT (39 patients). The same dose (5 micrograms/kg/day) and route of administration were employed in both groups. We found no significant differences in the time to reach an absolute neutrophil count (ANC) of 0.1, 0.5, and 1 x 10(9)/l and 50 x 10(9) platelets/l (medians: 10 and 11, 14.5 and 14, 17 and 16, 23 and 24 days, respectively, in groups A and B). We did not find differences in the days of fever or days on antibiotic treatment with less than 1 x 10(9)/l ANC, rate of bacteriemia, or days of hospitalization in both groups. In contrast, a considerable saving of G-CSF in B group was found (mean days of infusion in group A, 18, versus 11 in group B) (p < 0.0001). This is equivalent to a saving of 1120 $US per patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Ultrastructural co-localisation of vimentin and cytokeratin in visceral glomerular epithelial cells of dogs with glomerulonephritis.

The expression of cytokeratin and vimentin was studied in the glomerular epithelial cells of canine kidneys with and without glomerular abnormalities. Using ultrastructural, immunogold single and double labelling techniques, cytokeratin and vimentin were found together in the visceral glomerular epithelial cells (vGECs) of abnormal kidneys. In normal kidneys, the vGECs expressed only vimentin, and cytokeratin was found exclusively in parietal glomerular epithelial cells (pGECs). These results confirm previous findings in the same animals, obtained by immunohistological staining techniques.

Animals↗
PubMed1995

Administration of hepatitis A vaccine to a military population by needle and jet injector and with hepatitis B vaccine.

Military personnel are an important target population for hepatitis A immunization. Soldiers are often given vaccines by jet injector and may be required to receive multiple vaccines at one time. Formalin-inactivated hepatitis A vaccine containing 360 ELISA units of antigen was evaluated at Fort Campbell. Volunteers received vaccine at 0, 1, and 6 months as follows: group 1, hepatitis A vaccine by needle; group 2, hepatitis A vaccine by jet injector; group 3, hepatitis B vaccine by needle; and group 4, both hepatitis vaccines by needle in separate arms. Immune response and reactogenicity were evaluated. After two doses, recipients of vaccine administered by jet injector had a higher prevalence of antibody than those who received vaccine by needle (93% vs. 79%). By the 8th month, the vaccine was 100% immunogenic by either route or with hepatitis B vaccine. No interaction between hepatitis A and B vaccines was detected.

Adult↗
PubMed1995

Histological changes in the uterus during postpartum in the mare.

An histological study of the postpartum period in 29 mares was carried out. Uterine biopsies were taken daily during the first 10 days postpartum in a total of 87 samples. At day 0, equine endometrium was characterized in the surface by the presence of regularly ordered microcaruncles; the stratum spongiosum was oedematous and contained distended and scarce glands. Degenerative changes in microcaruncles and endometrial glands were present on day 1 postpartum. The epithelium of the microcaruncles from 2 to 5 days postpartum showed cytoplasmic vacuolization, karyorrhexis and an inflammatory reaction with neutrophils and phagocitic cells. On day 7 postpartum, the histology of the endometrium was similar to the normal proestrus with cuboidal luminal epithelium and an oedematous stromal tissue. The changes are usually completed within days 9 and 10 postpartum with the histologically typical appearance of estrus in mares.

Animals↗
PubMed1995

Molecular heterogeneity in childhood precursor B acute lymphoblastic leukemia with immunoglobulin heavy chain gene in germline configuration.

Four childhood acute leukemias with morphological, cytochemical and immunological characteristics correlating to precursor B lymphocyte and with germline configuration of the immunoglobulin heavy chain joining region were studied for the organization of the C mu segment. Two of the four lymphoblast samples retained the germline configuration of both JH and C mu regions. The other two samples showed delection of the entire JH region resulting in the rearrangement of the C mu region. In contrast to patients with C mu rearrangement, patients with C mu in germline form were not able to achieve complete remission after induction therapy. Study of the C mu region in patients with JH segment in germline configuration could separate subgroups in childhood precursor B acute lymphoblastic leukemia with different prognoses.

Adolescent↗
PubMed1995

Short report: an outbreak of trichinosis in Navarra, Spain.

Trichinosis is an infection contracted by ingestion of meat containing viable larvae of the nematode Trichinella spiralis. This report concerns an outbreak of infections with this parasite in Navarra, Spain that was associated with home-prepared pork products. After the detection of a person with trichinosis, a study of all subjects that had ingested meat from the presumably infected pork was carried out. Forty-four members of eight families were enrolled in the study. Ten had symptoms suggestive of trichinosis, 20 had hypereosinophilia, and 15 had positive serologic test results for anti-Trichinella antibodies. Three groups could be distinguished according to the kind of product each subject had ingested (pork sausage, blood pudding, and loin). Twelve months later, all had a normal eosinophil count and a negative serology.

Animals↗
PubMed1995

Surface modification with functionally active heparin.

Efforts to improve the blood compatibility of artificial materials have involved coating the surfaces with heparin. However, the anticoagulation activity of heparin is based on its binding to antithrombin, and if the specific structure involved in this interaction is compromised by the coating procedure, then the activity is lost. Surface modification with end-point-immobilized heparin has been found to be successful in inhibiting coagulation factors and minimizing complement activation.

Antithrombin III↗
PubMed1995

[Metrology of airborne particles carrying the principal air allergens].

The relationship between exposure to aeroallergens and the acquisition of allergy and asthma has been shown over the past ten years. Thanks to new developments for detecting major allergens amongst the principle aeroallergens, in future it will be possible to measure their airborne concentration and to determine the particle size of particles carrying them. We report the results obtained from three studies in which we have shown that airborne mites Group I and II and cockroaches Bla g 1 and Bla g 2 allergens have a broadly similar airborne behaviour. That is to say that they are not measurable unless the atmosphere is artificially disturbed and they are carried principally on particles of > 10 microns. On the other hand, 30-40% of cat allergens are carried on particles < 5 microns and measurable in the air without any artificial disturbance. According to our data and those of the literature, we propose a different classification for aeroallergens according to characteristic aerodynamics. Although some progress in the standardisation of techniques for sampling airborne allergens may have been accomplished, other studies are required to improve their reliability in order that airborne measurements can become a marker of allergic exposure in both domestic and occupational environment.

Air↗
PubMed1994

Coagulation inhibition capacities of low-molecular mass and unfractionated heparin, as determined by thrombin generation.

The common unfractionated heparin preparations (UFH) accelerate inhibition of most of the enzymes in the coagulation cascade, while low-molecular mass heparin (LMMH) mainly accelerates inhibition of activated coagulation factor X (FXa). The present study addresses the question of whether LMMH may be a weaker anticoagulant than UFH when the two preparations are added to plasma with equal FXa inhibitory activities. Normal and coagulation factor VIII (FVIII)-deficient plasma was used. Thrombin generation was determined by assaying the formation of the thrombin-antithrombin complexes (TAT) and of fibrinopeptide A (FPA), two parameters that showed a strong positive correlation. At a heparin concentration of 0.5 or 1.0 FXa-inhibiting IU/ml, the formation of TAT and FPA was substantial and always much more increased with LMMH than with UFH. At 4.0 FXa-inhibiting IU/ml, no FPA was generated, but traces of thrombin were. In recalcified FVIII-deficient plasma (one of the batches containing FVIII antibodies), more TAT was formed with 0.1 FXa-inhibiting IU/ml LMMH than with UFH with the same FXa-inhibiting activity. It is concluded that LMMH is a weaker anticoagulant than UFH, partly because of a poor thrombin inhibition capacity which facilitates acceleration of coagulation by FVIII activation and partly because of a poor inhibition of enzymes preceding the prothrombinase stage, both mechanisms leading to increased enzymatic activity above the prothrombin stage. As judged from the higher degree of thrombin generation with LMMH than with UFH, there is no support for the assumption that LMMH is as good an antithrombotic agent as UFH is, without reducing the haemostatic capacity as much as UFH does.

Antithrombin III↗
PubMed1994

The effect of plasma antithrombin concentration on thrombin generation and fibrin gel structure.

Congenital deficiency of antithrombin (AT) is associated with thrombotic events and AT consumption occurs in some severe disorders and after treatment with heparin. The aim of this study was to investigate whether variations in the level of plasma AT modify thrombin generation and the fibrin formation process after the intrinsic coagulation mechanism is triggered. Normal plasma was depleted of AT by immunoadsorption on CNBr-Sepharose coupled with the anti-AT-IgG fraction of antiserum. The AT-depleted plasma was reconstituted with AT (between 0.3 and 1.5 AT units per ml). Thrombin generation was measured as the development of thrombin-antithrombin complexes (TAT). The lag phase preceding fibrin formation depended on the concentration of AT. The short lag phase was seen in completely AT-depleted plasma and the long in plasma with 1.5 AT units per ml. TAT generation, determined in parallel consecutive samples, showed that the rate at which thrombin was generated was inverse to the AT concentration in plasma. The network structure of hydrated fibrin gels in the clotted plasma was studied by measuring the wavelength dependence of gel turbidity. The mass/length ratio value, -i.e. the thickness of fiber strands and porosity of the gel increased with increasing AT concentrations. It is concluded that plasma AT regulates the rate of prothrombin-thrombin conversion, the clotting time and the consequently network structure of the fibrin gel.

Antithrombin III↗