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Biomedical subjects

J M Alonso

Publications and source records attributed to J M Alonso.

At least 19 recordsLinked to original sources
PubMed1992

[Adrenal pheochromocytoma and metastatic intestinal carcinoid tumor in the liver. A purely accidental association?].

A patient with hepatic metastasis of an intestinal cancer tumor is presented. Six years previously the patient had been diagnosed of HTA secondary to pheochromocytoma of the left adrenal gland and surgery. The clinical findings are described and the results of scintigraphy with 123I-MIBG used for tumor detection are analyzed. The literature was revised and this unique presentation confirmed following the study and exclusion of a possible association with pluriglandular adenomatosis. Finally, following the poor results obtained with different therapeutic procedures in metastatic cancer tumors, the systematic, periodic determination of 5-HIAA, among other investigations, is suggested as a useful alternative in the early diagnosis and potential surgical treatment patients diagnosed of pheochromocytoma.

Adrenal Gland Neoplasms↗
PubMed1992

Inability of IL-2 and IL-10 to counteract B cell clonal deletion.

The B cell antigen receptor (BCR) delivers inhibitory signals in nascent B cells leading to the establishment of tolerance via clonal deletion or clonal anergy depending upon the type of antigen to which the B cells are exposed. In previous work, it has been demonstrated that activated Th2 cells, as well as some recombinant lymphokines, prevent the inhibition of growth and subsequent cell death induced through the BCR in model B cell lymphomas. Herein, we extend this work to another Th2 lymphokine, IL-10, that in contrast to IL-4 does not interfere with the deletion promoted by IgM crosslinking. The effect of individual lymphokines has also begun to be analyzed in a transgenic model of B cell clonal deletion. To this end, we have administered a recombinant vaccinia virus producing human IL-2 to mice expressing an autoreactive H-2Kk,b-specific transgenic IgMk and found that IL-2 does not abrogate B cell deletion in vivo.

Animals↗
PubMed1992

Swine leukocyte antigen and macrophage marker expression on both African swine fever virus-infected and non-infected primary porcine macrophage cultures.

Swine leukocyte antigens (SLA) and a macrophage specific marker were monitored on porcine macrophages cultured with or without macrophage colony stimulatory factor (M-CSF) and on cells infected with African swine fever virus (ASFV). SLA expression was maximal either in the total cell extract or on the cell surface at 3-4 days of culture; after 4 days these values began to decrease. Fluorescence analyses of immunostained macrophages cultured with or without M-CSF indicated a major upward shift in the number of SLA Class I molecules on individual macrophages whereas for SLA Class II both a novel expression of Class II and an upward shift in the number of molecules per cell were evident. Infection of 3-day-old macrophage cultures with three different isolates of ASFV resulted in minor changes in surface expression of SLA Class I, SLA Class II, and macrophage markers. No differences in infection with ASFV was observed whether macrophages were SLA Class II positive or negative, nor was there blocking by anti-SLA Class I or Class II monoclonal antibodies of ASFV infection of cultured macrophages.

African Swine Fever↗
PubMed1992

Bispecific anti-human red blood Rhesus-D antigen x anti Fc gamma RI targeted antibody-dependent cell-mediated cytotoxicity and phagocytosis by mononuclear leucocytes.

The Fc receptor mediated antibody-dependent cell-mediated cytotoxicity (ADCC) and phagocytosis induced by bispecific antibody (BsAb) to the high-affinity Fc receptor for IgG (Fc gamma RI) and to human red blood group antigen RhD were studied in vitro, using human mononuclear leucocytes as effector cells. The results were compared with those obtained by using a human monoclonal IgG1 anti-RhD used alone and a reference human polyclonal anti-RhD antibody. The effect of non-specific human IgG on FcR-mediated functions by mononuclear leucocytes was checked. The results demonstrate that BsAb presents a high resistance of Fc-mediated function to blockade by non-specific human IgG compared with that of both polyclonal and monoclonal anti-RhD antibodies. These results further encourage possible clinical application of bispecific antibody in passive immunotherapy.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1992

Responses of visual single cells in the superior colliculus of the albino rat to bright bars.

We studied the responses of 57 visual cells of the superior colliculus of the albino rat to bright sweeping and stationary flashing bright bars to determine the properties of their receptive fields. We observed that 9% (8% in superficial and 11% in deep layers) of the studied cells presented orientation preference and 16% showed direction selectivity (13% in superficial and 22% in deep layers). According to their responses to a flashed bright bar they were classified in OFF-type (19%) and ON-OFF-type (81%). No ON-type cells were found. All cells were driven by the contralateral eye, and only in three cases was single cell activation from the ipsilateral eye possible. Twenty-one per cent (22% in superficial and 18% in deep layers) showed end-stopping when they were tested with bright bars of several lengths.

Action Potentials↗
PubMed1991

Glucosidase II from rat liver microsomes. Kinetic model for binding and hydrolysis.

Glucosidase II is an enzyme involved in glycoprotein biosynthesis, releasing both alpha-1,3-linked glucose residues from the protein-linked oligosaccharide Glc2Man9GlcNAc2-R in the processing of N-glycans. We studied the kinetic properties of the enzyme, purified to homogeneity and, for the first time, we have been able to demonstrate the occurrence of two active sites in this enzyme and to establish the mechanisms of binding and hydrolysis of the physiological substrate at its active site(s). The analyses of data fitting to single and double hyperbolic equations and the Eadie-Hofstee profile, together with the inhibition kinetics, demonstrate that the enzyme has two different active sites. The Km and Vmax. values for the high-affinity site (site 1) were 0.78 mM and 437 munits/mg respectively, whereas the values for the low-affinity site (site 2) were 481 mM and 13797 munits/mg respectively, for the p-nitrophenyl alpha-D-glucopyranoside substrate. The Vmax./Km ratios, which indicate the efficacy of an active site for a substrate, were 560 and 28.7 ml/min per g for active sites 1 and 2, respectively. The inhibition type, with respect to site 1, for glucose, maltose, D-glucone-delta-lactone, CaCl2 and MgCl2 was pure-competitive, partial-competitive, parabolic, non-competitive and non-competitive respectively. Ki values for glucose, maltose, CaCl2 and MgCl2 were 6.75, 2.05, 10.60 and 14.20 mM respectively. Thus glucose would bind to active site 1, maltose to site 2 (and near to site 1) and D-glucone-delta-lactone to either site 1 or 2. The following hydrolysis mechanism for the physiological substrate (Glc2Man9GlcNAc2-protein) of glucosidase II may be concluded from all the foregoing kinetic evidence: the external glucose would be the first released residue, at active site 2, thereafter producing Glc1Man9GlcNAc2-protein; the remaining glucose would be released at active site 1, delivering the Man9GlcNAc2-protein product, which would leave the enzyme.

Animals↗
PubMed1991

Selective expansion of T cells bearing the gamma/delta receptor and expressing an unusual repertoire in the synovial membrane of patients with rheumatoid arthritis.

In a study of 7 patients with rheumatoid arthritis (RA), we characterized the T cell population present in the synovial membrane, thought to be the location where T cells trigger the disease. Synovial membrane lymphocytes from the RA patients were found to have a selective expansion of gamma/delta T cells (8.8% in synovial membrane versus 4% in peripheral blood). Expansion of the gamma/delta T cell subset was not found in the synovial membrane of patients with osteoarthritis. We characterized the gamma/delta T cell repertoire using monoclonal antibodies Ti gamma A, BB3, and delta TCS1, which recognize the gene products encoded by V gamma 9, V delta 2, and V delta 1-J delta 1, respectively. The majority of the synovial gamma/delta T cells did not express the repertoire encoded by these genes, which is found in nearly 100% of the peripheral blood gamma/delta T cells of healthy volunteer donors and in the thymus at early stages of development. We conclude that the synovial membrane of patients with RA displays a selective expansion of a specific population of gamma/delta T cells expressing a clonotypic receptor not yet serologically defined, which might be implicated in the development of the disease.

Adult↗
PubMed1991

Highly efficient expression of proteins encoded by recombinant vaccinia virus in lymphocytes.

Using a recombinant vaccinia virus (VV) that expresses E. coli beta galactosidase (beta-Gal) to infect lymphocytes, we show that enzymometrically or immunologically detectable beta-Gal expression is less pronounced among T cells than among B cells. VV infection caused growth inhibition of B cells, but barely affected T-cell proliferation in vitro. Moreover, the production of infectious viral particles was less pronounced in T lymphocytes. Kinetic studies revealed that after an initial dose-dependent growth inhibition, T cells continued to proliferate without the doubling time being affected by VV infection. Nonetheless, the T cells do express proteins encoded by recombinant VV, such as beta-Gal, or secrete soluble proteins such as interleukin-4, though at a lower efficiency at the per cell level than B lymphocytes. In conclusion, the physiology of T cells appears to be less perturbed by VV than that of B cells, although the virus is capable of directing expression of recombinant genes to T lymphocytes.

Animals↗
PubMed1991

Glucosidase II from control and ethanol-treated rats. Purification and properties.

Liver glucosidase II from control and ethanol-treated rats was purified and its physical and catalytic properties studied. No significant variation was found in the purification and properties of the enzyme from either source (ethanol-treated and control rats), except for activity after storage. Glucosidase II was purified to electrophoretic homogeneity from liver microsomes by solubilization, protamine sulphate precipitation, and anion exchange (DEAE-Sephacel) and affinity (Con A-Sepharose-4B) chromatographies. The native enzyme molecule is a tetramer (Mr 425 +/- 10 kDa) with identical subunits (Mr 106 +/- 3 kDa). Km values, determined at pH 6.8 for the p-nitrophenyl-glucosidase activity of glucosidase II from control and ethanol-treated rats, were 1.20 +/- 0.12 and 1.14 +/- 0.13 mM, respectively. The Arrhenius plot was linear, and the value for the apparent activation energy, calculated from this plot, was 56.64 kJ/mol. The p-nitrophenyl-glucosidase activity of glucosidase II from control and ethanol-treated rats was inhibited to the same extent by NH4+, by the divalent cations Ca2+ and Mg2+, and by methanol, ethanol, 2-propanol, n-propanol, isobutanol and n-butanol.

Alcoholism↗
PubMed1991

Contrast responses to bright slits of visual cells in the superior colliculus of the albino rat.

Contrast is the most effective stimulus in the visual system. The response of single cells to changes in stimulus contrast has been studied in a large variety of animals and the contrast response function determined. In the rat, studies on responses to contrast have been focused primarily in the geniculocortical pathway and there are relatively few in subcortical structures. We report here for the first time the contrast response function of single units located in the superior colliculus (SC) of the albino rat to several stimulus contrast. Cells in the SC require a relatively high contrast to elicit a reliable response and the dynamic response range is restricted to a short contrast interval.

Animals↗
PubMed1990

Ontogenic characterization of thymic B lymphocytes. Analysis in different mouse strains.

We have characterized a population of murine B lymphocytes present in the thymus (TBL). They are a minor subset (0.2%-1% of total thymocytes), present from perinatal periods onwards and constituted by activated cells with a high proportion of Ig-secreting cells. They represent the first B lymphocytes detected that secrete IgG after birth. Functional analysis reveals that the frequency of lipopolysaccharide-responding cells in TBL is 5- to 10-fold lower than in the spleen. TBL from adult mice did not show any significant difference in their VH repertoire expression when compared to peripheral B lymphocytes. Furthermore, we have been able to isolate a subpopulation of B220+IgM-CD3- thymocytes whose putative B cell precursor potential needs to be directly analyzed. These and other findings support the intrathymic resident characteristics of TBL and suggest new ways of elucidating its physiological role in the complex selective processes occurring inside the thymus.

Aging↗
PubMed1990

Lateral-posterior and pulvinar reaching cells--comparison with parietal area 5a: a study in behaving Macaca nemestrina monkeys.

In a previous study we have demonstrated the existence of pulvinar (puv) cells which were optimally activated when a monkey executed reaching movements with his limbs (Acuña et al 1983). We now describe further observations in four Macaca nemestrina monkeys trained to perform goal directed reaching movements aimed at four different positions in space. Extracellular unit activity in the lateralis posterior (lp) and puv nuclei, together with electrooculograms were recorded during the execution of the task. Seven hundred and sixty neurons were studied in the lp-puv complex. One hundred and twenty three cells (16%) showed changes in activity related to the reaching movements. Reaching related cells fell into two categories: goal direction sensitive (28/123 = 23%) and pandirectional (95/123 = 77%). Goal direction sensitive cells showed different responses depending on the direction of the goal relative to the starting point of the movement. The responses of the pandirectional cells were independent of goal direction. The activity of the remaining cells (637/760) could not be correlated with reaching movements. In a smaller number of area 5a (PE) cells (n = 109) studied in one monkey, 82 (75%) were classified as reaching related cells. Of these, 76% (62/82) were goal direction sensitive and 24% (20/82) pandirectional. The lp-puv cells were more dependent on the intentionality of movement than area 5a cells, and not reliably activated by passive manipulation of the limb. After injection of HRP-WGA in area 5a, where the reaching cells were recorded, labeled cells and terminals were located in the lp-puv zones where reaching cells were also found.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

[Evaluation of ceftazidime monotherapy in Pseudomonas aeruginosa bacteremias. Prospective study].

Twenty-six episodes of Pseudomonas aeruginosa bacteremia treated with intravenous ceftazidime, 4-6 g/day were evaluated. Treatment was begun within the first 24 hours after the isolation of the microorganism and was maintained for 10-12 days. In two patients with neutropenia amikacin was added during the initial 48-72 hours until the susceptibility to ceftazidime was known. All isolates were sensitive to ceftazidime. The most common underlying diseases were neoplasia (12), diabetes with stroke (4), neurosurgical and vascular procedures (4), rheumatoid arthritis (2), burns (2), cor pulmonale (1), and hypertension (1). The origins of bacteremia were urinary (12), pulmonary (9), and unknown (5). The infection was hospital-acquired in 77% and community-acquired in 23%. A critical clinical status and the presence of complications were significantly (p less than 0.01) associated with an increased mortality rate. Clinical outcome was good in 18/26 (70%), with a 30% mortality rate. The microbiological evolution showed 14 eradications, 6 persistences, 3 relapses and 3 colonizations. Resistance did not develop during therapy. Ceftazidime may be a good alternative therapy for these severe infections, although wider comparative studies are required for a better evaluation.

Adult↗
PubMed1989

Isolation and characterization of (gamma, delta) CD4+ T cell clones derived from human fetal liver cells.

Lymphocytes isolated from human fetal liver and expanded in vitro in IL-2-containing media reveal the existence of CD4+ gamma, delta T cells. These cells display differential features of double-negative and CD8+ gamma, delta T cells as well as of CD4+ alpha, beta T cells. Thus, they failed to lyse targets in lectin-mediated killing assays and to perform classical helper functions. These results add new information necessary for a better understanding of the physiological role of the gamma, delta T cells.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1989

Does the pulvinar-LP complex contribute to motor programming?

Extracellular unit recording studies in the pulvinar lateral posterior complex (Pul-LP) of behaving monkeys have shown a response property not previously reported. In monkeys performing aimed arm reaching movements towards frontally located targets some cells showed a change in activity beginning 495 +/- 84 ms before the onset of the reaching movement. This change in frequency precedes that observed in primary motor and parietal posterior cortex for reaching movements. These findings seem to indicate the involvement of the Pul-LP in motor functions and suggest its possible contribution to motor programming.

Action Potentials↗