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J B García

Publications and source records attributed to J B García.

10 recordsLinked to original sources
PubMed2003

HPLC studio: a novel software utility to perform HPLC chromatogram comparison for screening purposes.

A new tool, HPLC Studio, was developed for the comparison of high-performance liquid chromatography (HPLC) chromatograms from microbial extracts. The new utility makes it possible to create a virtual chromatogram by mixing up to 20 individual chromatograms. The virtual chromatogram is the first step in establishing a ranking of the microbial fermentation conditions based on either the area or diversity of HPLC peaks. The utility was used to maximize the diversity of secondary metabolites tested from a microorganism and therefore increase the chances of finding new lead compounds in a drug discovery program.

Algorithms↗
PubMed2000

Genetic diversity of the Junin virus in Argentina: geographic and temporal patterns.

RNA was purified from 39 strains of cell-cultured Junin virus (JUN) from central Argentina, which included both human- and rodent-derived isolates (a total of 26 and 13, respectively), as well as from 2 laboratory JUN strains, XJ Cl3 and XJ #44. JUN-specific primers were used to amplify a 511-nucleotide (nt) fragment of the nucleocapsid protein gene and a 495-nt fragment of the glycoprotein 1 (GP1) gene. Genetic diversity among JUN strains studied was up to 13% at the nt level and up to 9% at the amino acid (aa) level for the GP1 gene and up to 9% (nt) and 4% (aa) for the NP gene. Phylogenetic analyses of both genes revealed three distinct clades. The first clade was composed of the JUN strains from the center of the endemic area and included the majority of JUN strains analyzed in the current study. The second clade contained 4 JUN strains isolated between 1963 and 1971 from Cordoba Province, the western-most edge of the known endemic area. The third clade contained 4 JUN strains that originated from Calomys musculinus trapped in Zarate, the northeastern edge of the known endemic area. Certain JUN sequences, which were obtained from GenBank and identified as XJ, XJ #44, and Candid #1 strains, appeared to form a separate clade. Over 400 nt of the GP1 and GP2 genes were additionally sequenced for 7 JUN strains derived from patients with different clinical presentations and outcomes of Argentine hemorrhagic fever. Analysis of the corresponding aa sequences did not allow us to attribute any particular genetic marker to the changing severity or clinical form of the human disease.

Animals↗
PubMed2000

Screening of basidiomycetes for antimicrobial activities.

As a part of a screening programme developed to evaluate the antimicrobial activity of basidiomycetes, 317 isolates representing 204 species collected in Spain were screened against a range of human clinical pathogens and laboratory controls. Extracts from 45% of the isolates, representing 109 species, showed antimicrobial activity. Antibacterial activity was more pronounced than antifungal activity. The proportion of extracts from basidiomycetes showing antimicrobial activity was similar to or above that obtained for representative orders of Ascomycetes, such as Pezizales and Xylariales, but lower than that produced by members of the orders Diaporthales, Eurotiales, Hypocreales, Leotiales and Sordariales. Suprageneric taxa (orders and families) did not show pronounced differences in their antimicrobial activities though such differences were observed at the genus level, suggesting that the ability to produce these bioactive compounds is not homogenously distributed amongst the basidiomycetes. Isolates from some species showed large differences in their ability to produce metabolites with antimicrobial activity, possibly reflecting genetic differences at the infraspecific level.

Anti-Bacterial Agents↗
PubMed1988

Effect of superior cervical ganglionectomy on insulin release by murine pancreas slices.

The effect of superior cervical ganglionectomy (SCGx) on basal and glucose-stimulated insulin release in vitro was examined in pancreas slices of BALB/c mice subjected to surgery 14-96 h earlier. Fourteen or 20 h after SCGx a significant increase of insulin response to 11 mM glucose was detectable, while 96 h after SCGx a depression in response was found. Perifused pancreas slices obtained from mice subjected to SCGx 7 days earlier showed a decreased in vitro insulin response to glucose during both phases of insulin secretion. In sham-operated mice, injection of the beta-adrenoceptor blocker propranolol or of the cholinergic muscarinic antagonist atropine decreased basal and glucose-stimulated insulin release, while the alpha-adrenoceptor blocker phenoxybenzamine did not affect it significantly. In mice subjected to SCGx 14 h earlier, propranolol treatment decreased basal insulin release and impaired the release elicited by glucose to values similar to those found in controls, phenoxybenzamine injection increased the basal and amplified the enhanced glucose-stimulated insulin release, and atropine injection, although unable to affect basal insulin release, impaired partially the amplification of response detectable after surgery. Our results support the existence of significant effects of SCG neurons on insulin release in mice.

Animals↗
PubMed1987

Increase in insulin secretion induced by plasma from mice injected with allogeneic lymphocytes.

Plasma from BALB/c mice bled 90 minutes after allogeneic lymphocyte injection significantly rises glucose induced insulin secretion. This rise is observed in pancreas either from non-treated or from allogeneized mice. This rise is time and dose-dependent. An 1/40 dilution is enough to bring about a significant increase on insulin secretion. This effect is seen when mice are bled between 60 and 180 minutes after injection with a maximum effect at 90-120 minutes. Plasma from BALB/c mice injected with C57BL/6 J lymphocytes rises insulin secretion from BALB/c, C57BL/6 J, C3h and C57BL/KsJ mice pancreas. Plasma from streptozotocin diabetic BALB/c mice and from genetically diabetic C57BL/KsJ mdb-mdb mice injected with allogeneic lymphocytes stimulates glucose induced insulin secretion but to a lesser extent than plasma from normal non-diabetic mice does.

Animals↗
PubMed1986

Insulin secretion stimulated by allogeneic lymphocytes in an inbred strain of mice.

Effects of intraperitoneal injection of allogeneic lymphocytes on insulin secretion were studied in incubated pancreas slices from BALB/c mice. Injection of allogeneic lymphocytes from C57BL/6J (H2b) mice increased insulin secretion, both in basal and 11-mM glucose-stimulated conditions. This effect was only present when at least 5 X 10(6) or 1 X 10(6) cells were injected (in basal and stimulated conditions, respectively). Glucose-induced insulin secretion (3.3-27.5 mM) was significantly increased in pancreata from mice injected with allogeneic lymphocytes. No effect was observed when glucose was not included in the incubation medium. Intraperitoneal injection of Dextran 70 produced no change in glucose-elicited insulin secretion. There were no differences in glucagon and somatostatin (SRIF) secretion obtained from pancreas of mice injected with allogeneic or syngeneic lymphocytes. Injection of allogeneic cells increases insulin secretion (basal and both phases of 11 mM glucose-stimulated secretion). Puromycin significantly inhibited the second phase of insulin secretion. These results suggest that: Injection of allogeneic lymphocytes raises both basal and glucose-stimulated insulin secretion. This effect seems to be connected with the major histocompatibility complex, and to be related to the number of allogeneic cells injected. Injection of allogeneic lymphocytes seems to sensitize the beta cell response to glucose stimulus. Neither glucagon nor SRIF secretion are altered by alloantigen injection. The stimulatory effect of allogeneic lymphocytes is related, at least in part, to insulin synthesis.

Animals↗
PubMed1986

Insulin secretion induced by allogeneic lymphocytes in genetically diabetic mice C57BL/KsJ mdb.

Insulin and somatostatin (SRIF) secretion induced by alloantigen were studied in genetically diabetic mice from the C57BL/KsJ mdb-mdb strain. Diabetic (db) mice injected with allogeneic lymphocytes (A.L.) did not show any increase in their second phase of 27.5 mM glucose stimulated secretion and slightly increased their first phase. Normal A.L. injected mice showed a significant increase in both phases of 27.5 mM glucose stimulated secretion. SRIF secretion of A.L. injected normal and diabetic mice did not significantly differ from that obtained when injected with syngeneic lymphocytes. Lymphocytes from db mice injected into allogeneic mice caused an insulin secretion similar to that produced by allogeneic lymphocytes from non-diabetic mice. Lymphocytes from db mice injected into normal syngeneic mice caused an insulin secretion which was not significantly different from the one caused by syngeneic lymphocytes from non-diabetic mice, and is smaller than the secretion caused by A.L. injection. In summary, db mice showed an impaired hormone response to alloantigenic stimulus, while their lymphocytes maintained their alloantigenic action.

Animals↗