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Biomedical subjects

A Goday

Publications and source records attributed to A Goday.

At least 55 records · Page 3Linked to original sources
PubMed1989

Islet-cell antibodies: markers of a more severe insulin-dependent diabetes mellitus?

The aim of the present study was to analyze if an association exists between metabolic condition, C-peptide secretion and islet-cell antibody (ICA) presence in insulin-dependent diabetes mellitus (IDDM) at the clinical onset of the disease. Two hundred and nine IDDM patients were studied at diagnosis. 89% of the subjects showed residual C-peptide secretion that correlated inversely with blood glucose and glycosylated hemoglobin at diagnosis and with insulin requirement at discharge. Islet-cell antibodies were detected in 68.6% of the patients, complement-fixing ICA in 30% and insulin autoantibodies in 17.3%. Islet-cell antibody positive patients had a lower glucagon stimulated C-peptide than ICA negative subjects (0.41 +/- 0.22 versus 0.54 +/- 0.25 nmol/l, p = 0.005). However patients with high titers of ICA expressed in JDF units (JDF greater than 20) showed similar C-peptide secretion than ICA positive patients with a low level of JDF (JDF less than 20). When acid-base condition was analyzed patients on ketoacidosis at diagnosis had significant higher insulin requirement, lower C-peptide secretion and higher prevalence of ICA compared to patients that were not ketotic at diagnosis. Our findings suggest that residual beta-cell secretion plays a role on metabolic condition at diagnosis of IDDM and that ICA may be the markers of a more severe form of IDDM.

Adolescent↗
PubMed1988

The use of two-dimensional gel electrophoresis in the analysis of organ-specific maize proteins.

Two-dimensional gel electrophoresis with non-equilibrium pH gradient electrophoresis in the first dimension and sodium dodecyl sulfate-polyacrylamide gels in the second dimension has been used for the analysis of organ-specific proteins in maize. The method has been used to study the whole protein pattern of developing organs and adult leaves as well as protein patterns of in vitro translation. Examples of two-dimensional immunoblotting and in vitro translation of endosperm-specific proteins are also shown. Two-dimensional gel electrophoresis appears as an essential analytical step in the identification of organ-specific proteins and for the detection of the protein products related to organ-specific genes identified by other means.

Chloroplasts↗
PubMed1988

Gene Expression in Developing Zea mays Embryos: Regulation by Abscisic Acid of a Highly Phosphorylated 23- to 25-kD Group of Proteins.

We have earlier identified a set of proteins of 23 to 25 kilodaltons (kD), covering an isoelectric point (pI) range of 6.2 to 8.2, which accumulate gradually during normal embryogenesis of Zea mays and disappear in early germination. These polypeptides can be induced prematurely in immature embryos by abscisic acid (ABA) treatment. We report here that the more acidic protein forms are due to post-translational phosphorylation of at least two polypeptides of 23 kD, pI 8.2 and 25 kD, pI 8.0. A polyclonal antiserum was obtained which recognizes all forms of both the 23-kD and 25-kD polypeptides. Recovery of cDNA clones corresponding to these proteins was accomplished by hybridization with cDNA made from size-selected mRNA enriched for these sequences. Hybrid selection experiments demonstrate that clone MA12 specifically hybridizes with mRNAs encoding the 23-kD and 25-kD protein set which are recognized by the antiserum. By Northern hybridization analysis, the RNA encoded by clone MA12 is shown to accumulate in mature embryos and to be induced in young embryos upon ABA incubation.

Journal Article↗
PubMed1988

Erythromelalgia associated with acute diabetic neuropathy: an unusual condition.

Erythromelalgia is a syndrome characterized by erythema, burning pain and increased skin temperature of the affected extremities. It can be either primary (idiopathic) or secondary, but both forms require a critical temperature between 32-36 degrees C to provoke the crisis. Among the secondary forms, its association with diabetes mellitus is infrequent and its significance is little known. The histological studies have been fundamentally performed in patients with this syndrome affected by thrombocythemia; vascular thrombosis and fibromuscular intimal arteriolar proliferation were the prominent findings not corroborated in patients with the primary form. We studied one patient with acute diabetic neuropathy who developed erythromelalgia. We noted the absence of histopathological lesions, suggesting a disorder in vascular motility regulation favored by the severe neuropathy, without being able to discount a possible immunomediated mechanism. We describe the favourable evolution of the patient after treatment with aspirin and methysergide.

Acute Disease↗
PubMed1987

Transient immunologic defect in a case of Listeria rhombencephalitis.

We report a case of Listeria rhombencephalitis in a previously healthy 60-year-old man. Listeria rhombencephalitis is a rare but well-defined clinical syndrome of lower brain-stem involvement caused by Listeria monocytogenes. Contrary to other listerioses, rhombencephalitis has been mainly observed in patients without predisposing conditions. In our case, however, findings of a detailed immunologic study, performed three months and one year, respectively, after clinical onset of Listeria rhombencephalitis manifestations, showed a transient cellular immunity defect, not associated with any other apparent disease.

Encephalitis↗
PubMed1985

Human B lymphocytes and thymocytes but not peripheral blood mononuclear cells accumulate high dATP levels in conditions simulating ADA deficiency.

Inherited adenosine deaminase (ADA) deficiency is associated with a lymphospecific cytotoxicity affecting both dividing and non-dividing cells. The metabolic basis for this was investigated using different cell types and the potentially toxic metabolite 2'-deoxyadenosine (dAR) in short-term experiments under physiological conditions simulating ADA deficiency (1 mM Pi 8.7 microM dAR). In the uncultured cells, [8-14C] dAR alone was metabolized almost completely only by thymocytes and tonsil-derived B-lymphocytes. The greater percentage of counts (greater than 75%) were in the medium (deoxyinosine, hypoxanthine). Cellular counts were predominantly in adenine nucleotides, and to a lesser extent guanine nucleotides. Interestingly, both thymocytes and tonsil-derived B-lymphocytes, and a partially ADA deficient B lymphoblast line, accumulated detectable amounts of dATP even in the absence of ADA inhibition. Peripheral blood lymphocytes (PBMs) did not, and showed little dAR metabolism. In experiments simulating ADA deficiency varying amounts of 2'-deoxycoformycin (2'dCF) were needed to completely inhibit ADA (20-60 microM), with thymocytes requiring the highest amount. ADA inhibited thymocytes and tonsillar B-lymphocytes accumulated very high dATP levels, which were sustained to an equal extent by both over a 60-min period; PBMs accumulated the lowest values. Results in cultured cells reflected findings in previous studies. Some counts were also found in ATP by a route excluding ADA or PNP. These results again question the hypothesis that B-cells are more resistant than T-cells to the toxic effects of dAR because of an inability to accumulate and sustain elevated dATP levels and underline the lack of comparability between enzyme activity in intact as distinct from lysed cells. They cast doubt on the validity of cultured cells as a model for ADA deficiency and suggest the observed toxicity in some instances might result from altered ATP or GTP pools through inadequate ADA inhibition. They indicate that combined immunodeficiency in ADA deficiency could relate to an equal sensitivity of B-cells and T-cell precursors to the toxic effects of dATP accumulation.

Adenosine Deaminase↗
PubMed1985

Superoxide radicals, immunodeficiency and xanthine oxidase activity: man is not a mouse!

The importance of intact adenosine deaminase (ADA) activity in the generation of superoxide anion by xanthine oxidase has been disputed in studies using human neutrophils or mouse macrophages. The latter demonstrated a positive correlation between ADA activity and superoxide production during phagocytosis. The immunodeficiency in inherited ADA deficiency was related to a defect in this process. Since there is considerable interspecies variation in the tissue distribution of xanthine oxidase, the metabolism of [8-14C]deoxyadenosine (dAR), the toxic metabolite which accumulates in inherited ADA deficiency, was investigated in human peritoneal macrophages. Evaluation of the distribution of radiolabel in both cell and medium demonstrated that human macrophages with intact ADA metabolize dAR under physiological conditions to deoxyinosine and hypoxanthine exclusively. The hypoxanthine is further metabolized within the cell to ATP and GTP, via IMP. No xanthine or uric acid could be detected, confirming that in human macrophages xanthine oxidase activity is insignificant, as it is in most other human cells and tissues, except liver and intestinal mucosa. Thus production of superoxide radicals in such cells via this route would be impossible, and consequently unaffected either by ADA deficiency or the xanthine oxidase inhibitor allopurinol.

Deoxyadenosines↗
PubMed1985

EHNA is a poor inhibitor of deoxyadenosine catabolism in cultured human lymphocytes.

Erythro-9-(2-hydroxy-3-nonyl)-adenine (EHNA) has been used by many workers as enzyme inhibitor in vitro to simulate the in vivo situation in inherited adenosine deaminase (ADA) deficiency. In this study the metabolism of 8-14C deoxyadenosine (dAR) has been followed in cultured lymphocytes from patients deficient in enzymes associated with the catabolism and salvage of dAR, in the absence and presence of 10 microM EHNA. The results show that EHNA, at these concentrations, does not prevent the catabolism of dAR and thus does not provide a valid model for investigating the toxicity to the immune system in inherited ADA deficiency.

Adenine↗
PubMed1984

Metabolism of deoxynucleosides by lymphocytes in long-term culture deficient in different purine enzymes.

The metabolism of 8-14C-labelled 2'-deoxyadenosine (dAR) and 2'-deoxyguanosine (dGR) has been investigated using lymphocytes in long-term culture transformed by Epstein-Barr (EB) virus (B-cells) from eight patients with different inherited purine enzyme defects. The use of such lines enabled accurate mapping of the route of metabolism by acting as a 'trap' for the radiolabel at specific points. With either substrate (25 microM) most of the label was recovered in the medium. Using dAR, less than 30% of the radiolabel was incorporated into cellular nucleotides. For dGR, values were less than 18%. Studies with dAR alone confirmed the principal route of metabolism was to hypoxanthine, with further metabolism (by lines with intact salvage pathways) to ATP and GTP in the ratio of approximately 4:1. Lack of accumulation of deoxyinosine in the purine nucleoside phosphorylase (PNP) deficient line, or hypoxanthine in the hypoxanthine guanine phosphoribosyltransferase (HGPRT) deficient line, using dAR together with the adenosine deaminase (ADA) inhibitor 2'-deoxycoformycin (dCF) at 10 microM, confirmed the effectiveness of ADA inhibition. Nevertheless, some ATP was still formed by all lines in the presence of dCF by a route as yet unknown. Only the ADA deficient lines formed dATP with dAR alone. However, some dATP was formed by all lines in the presence of dCF. A partially HGPRT deficient line formed extremely high dATP levels, well in excess of those formed by the T-cell line CEM. Studies with dGR revealed some interesting differences, a large proportion of the substrate being metabolized predominantly to xanthine by most enzyme deficient lines. In the PNP deficient line most of the substrate remained unmetabolized, but some dGTP was formed. No other enzyme deficient line formed any dGTP--with or without the PNP inhibitor 8-aminoguanosine (8-NH2GR)--with one exception. Again this was the partially HGPRT deficient line, which with the inhibitor again formed more dGTP than the T-cell line. Within the cells most of the substrate was metabolized to GTP, except in the PNP, and totally HGPRT deficient lines. Levels of GTP formed were not altered by the inhibitor, reflecting the lack of effective PNP inhibition by 8-NH2GR. Some counts were also found in ATP and IMP, confirming the existence of this route in mammalian cells of lymphoid origin. The results also support previous studies by us using cell lines with intact purine pathways, which demonstrated that, contrary to current beliefs, some B-cell lines are capable of accumulating high levels of deoxynucleotides.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenosine Deaminase Inhibitors↗