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P Burgos

Publications and source records attributed to P Burgos.

6 recordsLinked to original sources
PubMed2003

Near-field scanning optical microscopy probes: a comparison of pulled and double-etched bent NSOM probes for fluorescence imaging of biological samples.

Bent near-field optical probes for biological applications have been fabricated using a combination of a two-step chemical etching method and focused ion beam milling to create a well-defined aperture. The transmission efficiencies have been evaluated as a function of laser wavelength (lambda) and aperture size (D) for both large and small core fibres. The probe transmission behaviour follows a (D/lambda)3 relationship. The double-etched probes are compared to pulled probes fabricated from highly GeO2-doped dispersion compensating fibre and a standard single-mode optical fibre. The transmission efficiencies of both types of pulled probes are approximately two orders of magnitude lower than double-etched probes with similar aperture sizes. To demonstrate the utility of the various probes, their imaging performance has been evaluated for samples of polymer beads and phase-separated phospholipid monolayers of dipalmitoylphosphatidylcholine or cholesterol/phosphatidylcholine/sphingomyelin mixtures. Both pulled and double-etched probes are suitable for fluorescence imaging of polymer spheres. However, pulled probes are rapidly damaged at the higher input laser intensities required for fluorescence imaging of monolayer samples doped with < 1% of a fluorescent dye-labelled lipid. The images obtained with the double-etched probes show excellent spatial resolution and signal/noise, illustrating the potential of such probes for imaging of biological samples.

Microscopy, Atomic Force↗
PubMed2002

Antiribosomal P protein antibodies in Chilean SLE patients: no association with renal disease.

The objective of this work was to determine the frequency and clinical associations of anti-ribosomal P protein antibodies (Anti-P) in a cohort of Chilean patients with systemic lupus erythematosus (SLE). Between 1996 and 1998, 141 consecutive patients with SLE were examined prospectively according with a standard protocol. Disease activity was measured by MEX-SLEDAI in 138 patients. Anti-P positivity was determined by double immune diffusion or Western blot and ELISA. Anti-P was found in 21 (15%) patients. In the Anti-P positive patients recent onset SLE (disease duration of 1 year or less) was more frequent (P = 0.018). Anti-P was found in 23% of 83 patients with active SLE vs 4% of the 55 patients with inactive SLE (Yates corrected P = 0.00479). An association with anti-dsDNA antibodies by Farr assay was observed. Anti-P positive patients had a median Farr of 65 IU/ml (1.4-1240) and Anti-P negative of 12 IU/ml (1.4-992; P-value = 0.0084). During the study only two patients had lupus psychosis and they were Anti-P positive. No association was found with liver disease (six patients, two with Anti-P antibodies) or active glomerulonephritis (22 patients four with Anti-P). Our data shows that the presence of Anti-P antibodies supports the clinical diagnosis of lupus psychosis.

Adolescent↗
PubMed2000

Increased expression of c-rel, from the NF-kappaB/Rel family, in T cells from patients with systemic lupus erythematosus.

OBJECTIVE: To explore the role of the NF-kappaB/Rel transcription factor family in autoimmunity, we investigated whether peripheral blood mononuclear cells (PBMC) and T cells from the blood of patients with systemic lupus erythematosus (SLE) exhibit abnormal expression of c-rel, both when recently isolated and/or during in vitro activation. METHODS: Total RNA and protein extracts were prepared from PBMC and T cells isolated by immunoadsorption with magnetic beads. The relative concentrations of c-rel mRNA and of c-Rel protein were determined by semiquantitative assays of competitive reverse transcriptase-polymerase chain reaction and chemiluminescent immunoblots, respectively. Activity of NF-kappaB/Rel was studied by electrophoretic mobility shift assay of nuclear extracts. RESULTS: Significantly increased levels of c-rel mRNA were found (1) in PBMC from SLE patients (n = 48; p<0.0000001), even during inactive disease (n = 11; p<0.001), compared to controls (n = 54), and (2) in T cells isolated from a subgroup of these patients (n = 11; p<0.00002) and controls (n = 12). c-Rel protein was found increased in the cytosol but not in the nucleus of PBMC of patients with SLE (n = 12; p<0.02) compared to controls (n = 12). No evidence of NF-kappaB/Rel nuclear activity was detected. In vitro stimulation of T cells by incubating PBMC with concanavalin A showed that less c-Rel entered the nucleus in lupus cells than healthy cells, correlating with lower interleukin 2 production. However, the same stimulating conditions provoked an increase in c-rel mRNA to higher levels in lupus cells from 2 patients compared with 2 controls. Increased levels of both IkappaB alpha and IkappaB beta could account for c-Rel cytosolic retention. CONCLUSION: Our data suggest that T cells from patients with SLE possess altered regulatory mechanisms of c-rel expression and nuclear import that might potentially determine conditions for developing autoimmunity. Other cells present in the PBMC could also be affected.

Adolescent↗
PubMed1997

Portacaval shunt control animals: physiological consequences derived from the sham operation.

The portacaval shunt in the rat is a frequently used experimental model of portosystemic encephalopathy. Among other consequences of this surgical preparation is an important decrease in hepatic and testicular volume. Different sham-operation methods including a laparotomy were used as controls in each case. Given that the liver volume varies greatly in comparison to body weight in the sham-operated animals, this paper aims to evaluate the possible consequences of the sham operation. It concludes that control animals without manipulation, in addition to the respective controls of portacaval shunt, should be used in every case.

Analysis of Variance↗
PubMed1994

Structural dimorphism in the mammillary bodies of the rat.

Diverse structures of the CNS show sexual differences in the anatomical and functional organization. In particular, many dimorphic nuclei have been found in the hypothalamus: the preoptic area, suprachiasmatic nucleus and ventromedial hypothalamus. Our investigation has shown a statistically significant difference in relation to volume of the medial mammillary and left lateral nuclei, and the number of glial cells of the medial mammillary nucleus. The volume and glial cell population is greater in the male than in the female. Thus, the existence of dimorphic functions in which this structure could be involved are discussed herein.

Animals↗