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Biomedical subjects

B García

Publications and source records attributed to B García.

At least 19 recordsLinked to original sources
PubMed1998

Molecular characterization of the phenylacetic acid catabolic pathway in Pseudomonas putida U: the phenylacetyl-CoA catabolon.

Fourteen different genes included in a DNA fragment of 18 kb are involved in the aerobic degradation of phenylacetic acid by Pseudomonas putida U. This catabolic pathway appears to be organized in three contiguous operons that contain the following functional units: (i) a transport system, (ii) a phenylacetic acid activating enzyme, (iii) a ring-hydroxylation complex, (iv) a ring-opening protein, (v) a beta-oxidation-like system, and (vi) two regulatory genes. This pathway constitutes the common part (core) of a complex functional unit (catabolon) integrated by several routes that catalyze the transformation of structurally related molecules into a common intermediate (phenylacetyl-CoA).

Acetyl Coenzyme A↗
PubMed1997

Platanus pollen as an important cause of pollinosis.

OBJECTIVE: The existence of Platanus pollinosis is not generally accepted despite the production of very large quantities of airborne Platanus pollen in many cities of the United States and Europe. The aim of this study was to investigate if Platanus pollen really contributes to the symptoms of the patients with pollinosis in the Madrid area. METHODS: We carried out systematic skin prick testing with Platanus pollen extract on 47 patients seen in our allergy center with spring-summer pollinosis symptoms. Each patient maintained symptom score diaries before, during, and after the Platanus pollination season. The average symptom scores were calculated and compared with the Platanus pollen counts. Measurements of specific IgE by ELISA and immunoblotting also were performed in each patient. RESULTS: The Platanus skin tests were positive in 33 of the 39 patients first seen with seasonal symptoms during Platanus pollen season and only in three of the eight patients without symptoms during Platanus exposure (Fisher's exact test; p < 0.05). Twenty-two of the 33 Platanus-positive skin test patients also had a positive ELISA result. Furthermore, the average 24-hour rhinitis symptom scores of the 39 patients first seen with seasonal symptoms during March through April showed significant correlation with Platanus pollen counts (r(s) = 0.57, p < 0.05). The immunoblot results suggest that a 17 kd pollen protein could be a major allergen in patients with Platanus pollinosis. CONCLUSIONS: Platanus pollen is an important cause of pollinosis in Madrid. A protein with a molecular weight of 17 kd appeared to be its major allergen.

Adolescent↗
PubMed1997

Norepinephrine potentiates the mitogenic effect of growth factors in quiescent brown preadipocytes: relationship with uncoupling protein messenger ribonucleic acid expression.

Rat brown preadipocytes cultured in low serum conditions increase DNA synthesis and proliferate in response to serum and a variety of growth factors and hormones. Epidermal growth factor, platelet-derived growth factor, and acidic and basic fibroblast growth factors stimulate DNA synthesis in a dose-dependent manner and induce at least a 5-fold increase in [3H]thymidine incorporation after 40 h of exposure. The physiological activator of brown adipose tissue, norepinephrine, has a low mitogenic effect per se, but increases DNA synthesis stimulation exerted by serum, epidermal growth factor, basic fibroblast growth factor, and the neuropeptide vasopressin. The addition of vasopressin plus norepinephrine greatly potentiates the mitogenic effect of growth factors to levels comparable to the effect of 10% serum. Preadipocytes cultured in the presence of these mitogen combinations (growth factor, vasopressin, and norepinephrine) express a differentiation marker, the uncoupling protein. Thus, our results show 1) that a variety of growth factors and hormones induce DNA synthesis in a synergistic fashion in brown preadipocytes in primary culture; and 2) there is evidence for a role of norepinephrine in the regulation of brown adipocyte proliferation, potentiating the action of serum and mitogens, besides its role in uncoupling protein messenger RNA expression.

Adipocytes↗
PubMed1996

Molecular cloning and expression in different microbes of the DNA encoding Pseudomonas putida U phenylacetyl-CoA ligase. Use of this gene to improve the rate of benzylpenicillin biosynthesis in Penicillium chrysogenum.

The gene encoding phenylacetyl-CoA ligase (pcl), the first enzyme of the pathway involved in the aerobic catabolism of phenylacetic acid in Pseudomonas putida U, has been cloned, sequenced, and expressed in two different microbes. In both, the primary structure of the protein was studied, and after genetic manipulation, different recombinant proteins were analyzed. The pcl gene, which was isolated from P. putida U by mutagenesis with the transposon Tn5, encodes a 48-kDa protein corresponding to the phenylacetyl-CoA ligase previously purified by us (Martínez-Blanco, H., Reglero, A. Rodríguez-Aparicio, L. B., and Luengo, J. M. (1990) J. Biol. Chem. 265, 7084-7090). Expression of the pcl gene in Escherichia coli leads to the appearance of this enzymatic activity, and cloning and expression of a 10.5-kb DNA fragment containing this gene confer this bacterium with the ability to grow in chemically defined medium containing phenylacetic acid as the sole carbon source. The appearance of phenylacetyl-CoA ligase activity in all of the strains of the fungus Penicillium chrysogenum transformed with a construction bearing this gene was directly related to a significant increase in the quantities of benzylpenicillin accumulated in the broths (between 1.8- and 2.2-fold higher), indicating that expression of this bacterial gene (pcl) helps to increase the pool of a direct biosynthetic precursor, phenylacetyl-CoA. This report describes the sequence of a phenylacetyl-CoA ligase for the first time and provides direct evidence that the expression in P. chrysogenum of a heterologous protein (involved in the catabolism of a penicillin precursor) is a useful strategy for improving the biosynthetic machinery of this fungus.

Adenosine Monophosphate↗
PubMed1995

Involvement of nitric oxide in bone marrow-derived natural suppressor activity. Its dependence on IFN-gamma.

Bone marrow (BM)-derived natural suppressor (NS) cells are strong inhibitors of lymphoproliferative responses. In this study we have assessed the involvement of nitric oxide (NO) in BM-derived NS activity, as detected in cocultures of BM and spleen cells stimulated with B cell (LPS) or T cell (Con A) mitogens. The results indicate that NS activity is readily inhibited by NG-monomethyl-L-arginine, a competitive inhibitor of NO synthase, or N-acetylcysteine, a free radical-scavenging thiol compound. High amounts of nitrite, a stable end product of NO, are detected only in supernatants of Con A- or LPS-stimulated spleen cells cocultured with BM cells enriched in NS activity (Fr3 cells). These amounts (15 to 55 microM) are strongly antiproliferative for both Con A and LPS responses, as was established with a nitrite curve made with a NO donor (sodium nitroprusside). Fr3 cells cultured alone release large quantities of NO and express inducible NO synthase (iNOS) mRNA upon LPS stimulation, but require spleen cells in cultures stimulated with Con A. Anti-IFN-gamma-neutralizing Abs blocked both NO production and NS activity, irrespective of the mitogen used; yet, only exogenous IFN-gamma is unable to promote successful NO production by Fr3 cells, but does induce detectable iNOS mRNA expression in these cells. Taken together the results indicate that: 1) NO is the major mediator of BM-derived NS activity; 2) BM cells enriched in NS activity produce large amounts of NO through an IFN-gamma-dependent iNOS induction.

Acetylcysteine↗
PubMed1993

Febrile ulceronecrotic Mucha-Habermann disease.

Febrile ulceronecrotic Mucha-Habermann disease in an 18-year-old man is reported. This disease is a severe form of pityriasis lichenoides et varioliformis acuta (PLEVA) and is characterized by the sudden onset of diffuse coalescent ulcerations associated with high fever and systemic symptoms. In the present case the disease was preceded by typical PLEVA. Histologically, a leukocytoclastic vasculitis was seen in addition to the usual features of PLEVA. Findings of laboratory studies revealed an elevated erythrocyte sedimentation rate, a high white blood cell count, and a mild increase in liver enzymes. No systemic involvement was detected. Findings of T cell receptor gene analysis in skin and peripheral blood showed no abnormality. The patient was treated with PUVA and methotrexate with a good response. We review the eight previously reported cases of febrile ulceronecrotic Mucha-Habermann disease.

Adolescent↗
PubMed1993

[The stability of antibiotics administered in and with a parenteral nutrition mixture enriched with branched-chain amino acids. I. Amikacin and gentamycin].

The combined infusion of antibiotics and parenteral nutrition makes it possible to maintain plasmatic nutrient concentrations over time, in turn facilitating the administration of the antibiotics in the dilution and infusion time recommended according to their pharmacokinetic parameters. On the other hand, this type of administration has care benefits for the patient, reducing the risk of infections, and adding to comfort. The technique is also cost-effective, reducing the cost of drug administration, saving on administrative personnel and nursing staff time. The stability of amikacin and gentamicin are determined in vitro at therapeutic concentrations jointly infused with a mixture of parenteral nutrition with polyols and enriched in ramified chain amino acids. A microbiological stability analysis was carried out of the antibiotics in the parenteral nutrition, along with an HPLC aminogram, in order to determine the concentration of amino acids in the combined infusion with the antibiotic. pH measurements were also taken, along with osmolarity and colour change. Both of the antibiotics and the parenteral nutrition employed, and of the combined infusion mixtures. Amikacin and Gentamicin are stable at a concentration of 5 mg/ml and 1.6 mg/ml respectively in a parenteral nutrition mixture enriched in ramified chain amino acids.

Amikacin↗