Search PubMed⌕ Search

Biomedical subjects

B Sanchez

Publications and source records attributed to B Sanchez.

At least 19 recordsLinked to original sources
PubMed1992

Bilateral distribution of aminopeptidase activities in selected structures of a photoneuroendocrine circuit and other rat brain areas.

Provided that soluble aminopeptidases, the most abundant proteolytic enzymes found in brain, are involved in the metabolism of several neuropeptides, their activity could be a reflect of neuropeptide function. Therefore, in order to analyze their rate of participation, we have measured 4 soluble aminopeptidase activities: leucine aminopeptidase, arginine aminopeptidase, aspartate aminopeptidase, and pyroglutamate aminopeptidase, using arylamide derivatives as substrates, in selected structures integrating the photoneuroendocrine circuit related to the melatonin rhythm generating system and other rat brain areas. The regional distribution of all the activities was heterogenous: a 3-fold (leucine-, arginine- and aspartate-aminopeptidase) and 5-fold (pyroglutamate aminopeptidase) difference was observed between the regions with the highest and lowest activity. Significant differences were displayed between the left and right retina for pyroglutamate aminopeptidase and arginine aminopeptidase activities. High levels of pyroglutamate aminopeptidase were evident in the retina and adenohypophysis, which is consistent with a role for thyrotropin releasing hormone in photoreceptive mechanisms, and support its well established role in controlling thyrotropin releasing hormone in anterior pituitary. The presence of a high activity rate of aspartate aminopeptidase in adenohypophysis implies an active participation of angiotensin peptides at this level.

Aminopeptidases↗
PubMed1992

A human monoclonal autoantibody to a nucleolar structure.

Peripheral blood lymphocytes from a scleroderma patient (CDC) were isolated, transformed with Epstein-Barr virus and fused to the heteromyeloma SHM-D33. Supernatants from cultures were screened for autoantibody production against nucleoprotamine by ELISA. Positive wells were cloned by limiting dilution. After cloning, supernatants from two wells were positive for the nucleoprotamine assay. One named CDC-1 has been studied in our laboratory. CDC-1 recognized a nucleolar antigen by indirect immunofluorescence. By using an ELISA with purified recombinant antigens, CDC-1 reacted against Ro/SS-A, U1 (RNP) and Sm. By immunoblotting using a lysate of MOLT-4 cell line, CDC-1 was able to react against a structure of 60 kD. When the antigen recognized by CDC-1 was purified, SDS-PAGE under reducing conditions with purified antigen and subsequent silver staining of the gel allowed us to detect three bands at 60, 55 and 39 kD, respectively. A screening by ELISA with previously characterized antisera against our purified antigen demonstrated reactivity of the CDC-1 antigen with those antisera able to recognize Ro/SS-A.

Antibodies, Antinuclear↗
PubMed1992

Production of heterohybridomas secreting autoreactive and polyreactive human monoclonal antibodies.

Peripheral blood lymphocytes from two polytransfused renal dialysis patients were transformed by Epstein-Barr virus, fused to a heteromyeloma and cloned. Eight human monoclonal antibodies from the resulting clones were tested for their binding to a variety of antigens by ELISA, indirect immunofluorescence and immunoblotting. Antigens tested included B-cell lines, T and B lymphocytes, red blood cells, chronic lymphocytic leukaemic B cells, IgG, ssDNA, dsDNA, histones, nucleoprotamine, sperm nuclei, thymus and spleen extracts, MOLT4 cell lysates, affinity purified autoantigens, tetanus toxoid, bacterial lipopolysaccharide, insulin, and a tissue section screen. These human monoclonal antibodies reacted with more than one antigen to varying degrees and were autoreactive and polyreactive. One of these heterohybridoma cell lines exhibited cytoplasmic staining with an anti-CD5 monoclonal. Our findings support the concept that in adult individuals a subset of B cells produce heterogeneous IgM antibodies which can bind to a variety of different autoantigens and also to foreign antigens. These monoclonals were different from the autoantibodies usually seen in renal dialysis patients in the sense that they were not lymphocytotoxic.

Antibodies↗
PubMed1992

Perinatal prevalence of B hepatitis markers.

The present investigation describes the prevalence of markers detected in immunoenzymatic methods, for infection by the hepatitis B virus in sera of mothers and newborn umbilical cord blood in Merida, Venezuela. The sample population was composed of 500 mothers who attended the Obstetrics Department, University Hospital of los Andes, for their delivery between May and October 1990. The global prevalence figure of 11.8% showed a balanced distribution for surface antigen and its antibody. Prevalence for the urban area was 13.49% (RR = 1.49) and 11.80% for mothers from the rural zones (RR = 0.67), 95%, IC 0.63 to 1.9). A statistical difference was found between mothers with two or more live children (14 cases) and those with one or no children (7 cases) for anti-HBs (X2 = 7.62, p < 0.05, RR = 1.43, CI 0.47 to 2.86). Mothers with a history of several sexual partners showed a prevalence of 18.0%, RR = 1.5, CI 0.58 to 2.44, while those who were students, 18.3%, RR = 1.64, CI 0.94 to 2.5. These data may be indicating that sexual transmission mechanisms are of utmost importance, yet more precise investigations are required to confirm this hypothesis. Blood samples from umbilical cord were all negative for surface antigen.

Biomarkers↗
PubMed1992

[An unusual pericardial tumor: bronchogenic cyst].

The authors report the case of an intrapericardial bronchogenic cyst in a 42 year old woman with no cardiac symptoms. Despite extensive investigation, the final diagnosis was made only at anatomopathological examination. A pericardial localisation of this embryological tumour is very rare and a number of features of the condition are described. In this case, the carbohydrate antigen (CA 19-9) was a veritable marker of this tumour. This association, described for the first time, between a simple biological marker and an intrapericardial bronchogenic cyst, could be a valuable diagnostic aid in a pathology in which surgery could reasonably be deferred should the diagnosis of bronchogenic cyst be certain.

Adult↗
PubMed1991

Cloning of human heterohybridoma cell lines using chronic lymphocytic leukemia B cells as a feeder layer.

B cells from the peripheral blood of chronic lymphocytic leukemia patients were isolated by gradient density centrifugation and used without irradiation as a feeder layer in the cloning of human heterohybridoma cell lines by limiting dilution. Cloning efficiencies were high with all the cell lines tested. These feeder leukemia B cells could also be successfully used after having been stored in liquid nitrogen.

Animals↗
PubMed1991

Pinocembrine: a bioactive flavanone from Teloxys graveolens.

Bioactivity directed fractionation of the acetone extract of Teloxys graveolens (Willd.) Weber (Chenopodiaceae), using the brine shrimp lethality test, led to the isolation of 5,7-dihydroxyflavanone (pinocembrine) (LC50 = 4.25 micrograms/ml) as the only active compound. Pinocembrine also exhibited fasciolicide, ovicide and larvicide activities on newly excysted Fasciola hepatica, on infective eggs of Ascaridi galli and on stage three larvae of Stomoxys calcitrans, respectively.

Animals↗
PubMed1991

Triiodothyronine-receptor complex in rat brain: effects of thyroidectomy, fasting, food restriction, and diabetes.

In vitro saturation analysis combined with quantification of T3, by an isotopic equilibrium technique or RIA, were used to examine the effects of thyroidectomy, fasting, diabetes, and food restriction on T3 concentration and specific binding in cerebral cortex and cerebellum. Fasting and food restriction did not affect the T3 binding parameters in the brain areas studied. Both thyroidectomy and diabetes were accompanied by a reduction in T3 content in nuclei from both cerebral cortex and cerebellum, but a decrease in T3 binding sites was only observed in both brain areas of diabetic animals. No significant differences in the binding affinity values among the experimental groups were seen. The diabetes-induced decrease in T3 content and receptor number were completely reversed by insulin treatment. Studies with fractionated nuclei from cerebral cortex and cerebellum showed that diabetes resulted in a reduction in T3 content and the number of receptors in glial nuclei from both brain areas. Although T3 content was also decreased in neuronal nuclei, the receptor concentration in these nuclear preparations did not change in concentration or affinity under the same conditions. These observations indicate that glial cells, not only have T3-binding characteristics similar to those of neuronal cells, but the T3 receptor number is decreased in the diabetes state.

Animals↗
PubMed1991

Diurnal variation and left-right distribution of pyroglutamyl peptidase I activity in the rat brain and retina.

The thyroliberin and luliberin contents exhibit a diurnal rhythm within the brain and an asymmetrical distribution of both neuropeptides has been demonstrated in the hypothalamus. Since they have been described as substrates of pyroglutamyl peptidase I, this activity was analysed in several rat brain regions and other structures, in order to investigate its putative diurnal variations and changes in relation to the distribution of these neuropeptides and/or other susceptible substrates. Fluorometric activity was assayed in the retina, pituitary gland, superior cervical ganglia, pineal gland, some selected brain regions, and serum of adult male rats at six different time points of a 12:12 h light:dark cycle, using pyroglutamyl-beta-naphthylamide as substrate. A significant circadian rhythm was demonstrated in the retina, the hypothalamus, and the intermediate-posterior pituitary lobe. In addition, a small but significant asymmetrical distribution of this activity, at certain time points, was disclosed: The activity was higher in the left than in the right retina at 10 h of the light period, whereas it was predominant in the right side at 01 h of the dark period. Furthermore, the activity was higher in the left anterior than in the right hypothalamic area at 13 and 01 h. These results could be indicative of a role of this enzymatic activity in the control of the functional status of its endogenous substrates.

Animals↗
PubMed1990

Mn2(+)-activated aspartate aminopeptidase activity, subcellular localization in young and adult rat brain.

The levels of soluble and membrane-bound aminopeptidase activities were assayed in subcellular fractions from young (4 weeks old) and adult (20 weeks old) rat brains, using Asp-2-naphthylamide as substrate. The young rats showed the highest soluble and membrane-bound levels of activity in the microsomal fraction but no differences among fractions were found at 20 weeks of age. The membrane-bound activity was significantly higher than the soluble one in all subcellular fractions of young rats. Soluble activity of the homogenate and the mitochondrial fraction was significantly increased in adult animals when compared to that of younger ones.

Aging↗
PubMed1990

Characterization of three human monoclonal antibodies specific for polymorphic class I and class II HLA antigens.

Three human monoclonal antibodies were derived from a single polytransfused patient awaiting renal transplantation. In microcitotoxicity assays, the patient's serum displayed strong positive reactions against greater than 90% of a panel of cells representing the known HLA specificities. The donor's peripheral blood lymphocytes were infected with Epstein-Barr virus, cloned, and supernatants of the virus transformed cultures were screened for the presence of IgG antilymphocyte reactivity utilizing an enzyme-linked immunosorbent assay method. Positive cultures were recloned and fused with the human-mouse heteromyeloma SHM. Supernatants from three clones were selected for alloreactivity and characterized by indirect immunofluorescent staining and fluoroactivated cell sorter analysis on homozygous typing cells, including those from the Tenth International Histocompatibility Workshop core panel and on cell lines derived from selected families. Data obtained demonstrate that two human monoclonal antibodies have DQw1 specificity, one of them being reactive against several DQw7-positive cell lines, while one monoclonal antibody is specific for the A2 + A28 class I MHC antigens. Anti-DQw1 antibodies were of different light-chain subtypes.

Antibodies, Monoclonal↗
PubMed1990

Neurologic complications of axillary and brachial catheter arteriography in atherosclerotic patients: predictive factors.

Catheter arteriography by the axillary or brachial route can be responsible for central neurologic complications. The objectives of this prospective study were to define the predictive factors of these complications and determine their incidence. This report is based on 288 consecutive arteriography sessions performed between January 1985 and June 1987. All patients had arterial atheromatous pathology. Ten central neurologic complications (3.5%) occurred, two of which (0.7%) were permanent. Four factors were significantly associated with increased incidence of central neurologic complications: antecedent transient ischemic attack (p less than 0.001); tight (greater than 80%) stenosis of at least one internal carotid artery (p less than 0.02); angina pectoris (p less than 0.05); age over 80 years old (p less than 0.001). Seldinger's or Dos Santos' techniques are preferable to axillary or brachial catheter techniques for investigation of the lower limbs and the abdominal aorta. The former obviates the need to catheterize the aortic arch and reduces the risk of embolism to the supraaortic arteries. Digital venous arteriography is an alternative to aortic arch catheterization when investigating the supraaortic arteries in the presence of risk factors.

Age Factors↗
PubMed1990

[Protection and reperfusion of the myocardium by cardioplegia with blood enriched in aspartate and glutamate. Technique and initial results. Report of 60 cases].

From 1st November 1987 to 30th September 1988, 27 patients with recent myocardial infarction and 33 patients at high risk of postoperative circulatory failure were operated according to the same protocol. In each case, myocardial protection, at the time of aortic clamping, consisted of an intra-coronary injection of a cardioplegic solution of blood enriched with aspartate and glutamate, administered in 3 phases (normothermic induction, hypothermic induction, normothermic reperfusion) according to the protocol described by Buckberg et al. The operative mortality was 11.6% (7/60) and 46.6% (28/60) of patients did not develop any postoperative complications. It is difficult to draw any conclusions concerning the superiority of the method on the basis of a non-comparative clinical study, but its simple application and its safety appear to be clearly demonstrated.

Adult↗
PubMed1990

Learning to learn.

Explore the source record for details and available documents.

Administrative Personnel↗
PubMed1989

[Intra-aortic balloon counterpulsation. Percutaneous insertion at surgical units. Apropos of 170 cases].

From 1st January 1985 to 31st December 1987, an intra-aortic balloon counterpulsation device (IABCP) was inserted in 170 patients: 166 balloons were inserted percutaneously and 4 surgically after failure of the percutaneous route. The indications for insertion of IABCP are classified into 3 categories. Category 1 (N = 28) consists of non-operated patients, category 2 (N = 60) consists of patients in whom IABCP balloons were inserted by necessity before, during of after a surgical operation under cardiopulmonary bypass (CPB) and category 1 (N = 82) consists of patients in whom the IABCP balloons were inserted prophylactically prior to an operation under CPB in patients at high risk. Sixteen patients with a percutaneous IABCP balloon developed a major complication related to the balloon (9.6 +/- 2.3%). The early mortality for the entire population was 49.4 +/- 3.8% (84/170). The mortality was 89 +/- 6% (25/28), 65 +/- 6% (39/60) and 24 +/- 5% (20/80) respectively in categories 1, 2 and 3. In category 3, 56 IABCP balloons (68.3%) were retrospectively considered to be necessary (group A). Nineteen patients in group A died (34 +/- 6%). The mortality observed in the 30 patients in category 2 in whom an IABCP balloon was required during the intra- or post-operative period (group B) was 76.6 +/- 7.7% (23/30). It was significantly higher than that observed in group A (p less than 0.001). However, the retrospective nature of this study prevented any formal conclusions concerning the benefit provided by prophylactic IABCP.

Adult↗
PubMed1988

HLA-Dw14 and HLA-DR3 haplotypes share a functional determinant recognized by a human alloreactive T-cell clone.

In the process of studying the fine specificity of HLA class II molecules, we identified an alloreactive T-cell clone raised to a HLA-Dw14 homozygous cell line that was specifically stimulated by Dw14+ homozygous typing cells but negatively with cells expressing the HLA-Dw4,-Dw10, -Dw13, and -Dw15 subspecificities of DR4. Of interest, this clone was also equivalently activated by stimulation with all DR3 cells and cell lines tested. Negative responses were obtained using a panel of 87 non-DR3 and non-Dw14 cells, including cell lines of the Tenth Histocompatibility Workshop. A monoclonal antibody inhibition study revealed the relevant stimulating determinant to be on HLA-DR molecules in both Dw14- and DR3-positive cells. A comparison of the DR beta 1-chain-inferred amino acid sequences suggests that formation of a topologically equivalent stimulating determinant would involve the participation of two noncontiguous regions of the third diversity region of DR beta 1. The putative recognition conformation detected by the clone is most probably specified by the presence of a valine at position 86 and a nonnegatively charged residue at positions 70, 71, and 74, since these are the only residues where DR3 and Dw14 are distinguishable from all other HLA-DR types. These findings illustrate that the functional ability of class II molecules is not necessarily either illustrated or predicted by serologic typing or by simple considerations of amino acid sequence.

Amino Acid Sequence↗
PubMed1988

Autologous fibrin tissue adhesive: factors influencing bonding power.

Bonding power of Autologous Fibrin Tissue Adhesive (AFTA) is directly related to its fibrinogen concentration. By increasing the ammonium sulfate concentration 100% during fibrinogen precipitation, the bonding power of two glued 1-cm2 pieces of human dura almost doubled. No relationship between blood fibrinogen level and bonding power was demonstrated. Comparing AFTA with Fibrin Sealant, the commercial fibrin tissue adhesive, shearing strength between two glued pieces of human dura with AFTA was less 10 minutes and greater 30 minutes after gluing. Gluing a TORP (Richards) to a 1-cm2 piece of human dura yielded generally somewhat greater bonding power when using Fibrin Sealant. Autologous Fibrin Tissue Adhesive provides bonding power adequate for middle-ear surgery, eliminates transmission of viral diseases and, unlike Fibrin Sealant, AFTA is available in the United States.

Ammonium Sulfate↗