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Biomedical subjects

L Fuentes

Publications and source records attributed to L Fuentes.

At least 19 recordsLinked to original sources
PubMed2006

Lipid peroxidation in ischemia-reperfusion oxidative injury of the graft preserved in Celsior and University of Wisconsin solutions on a pig pancreas transplantation model.

BACKGROUND: Graft pancreatitis (GP) is one the main technical problems associated with pancreas transplant (PT). It occurs in 20% of patients representing a risk factor for thrombosis and cause of graft loss. GP is related to oxidative effects from oxygen-derived free radicals (OFR) in ischemia-reperfusion injury. We evaluated lipid peroxidation by the OFR in the PT of pig organs preserved with either Celsior or Wisconsin solutions. METHODS: In Landrace pigs we performed 24 pancreas allografts, which were preserved 18 or 24 hours: 12 with Celsior solution (CS) and 12 with Wisconsin solution (UW). No immunosuppression was administered. The oxidative effects were determined by quantification of malondialdehyde (MDA) and 4-hydroxyalkenals (4-HDA) and of the carbonyl groups of proteins in our pancreatic tissue samples and measured at different times: (A) baseline in the donor, (B) after perfusion of the graft, (C) after the ischemia period, and (D) 30 minutes after ischemia-reperfusion of the graft. RESULTS: The MDA and 4-HDA values were similar in conditions A, B, and C, but showed an extraordinary increase after ischemia-reperfusion in D, among both the 18- or 24-hour preserved grafts and in the same proportion with CS and UW. The carbonyl groups of the proteins rose in conditions B and C (cold ischemia), but less so in state D (reperfusion). CONCLUSIONS: The oxidative injury of a pancreatic graft preserved for 18 or 24 hours occurs during reperfusion, with an extraordinary intensity, but similarly with CS and UW, an observation that may help to explain graft pancreatitis.

Adenosine↗
PubMed2005

Effects of trace elements on membrane fluidity.

According to the Fluid Mosaic Model, a biological membrane is a two-dimensional fluid of oriented proteins and lipids. The lipid bilayer is the basic structure of all cell and organelle membranes. Cell membranes are dynamic, fluid structures, and most of their molecules are able to move in the plane of the membrane. Fluidity is the quality of ease of movement and represents the reciprocal value of membrane viscosity. Fluid properties of biological membranes are essential for numerous cell functions. Even slight changes in membrane fluidity may cause aberrant function and pathological processes. Several evidences suggest that trace elements, e.g., iron, copper, zinc, selenium, chromium, cadmium, mercury and lead may influence membrane fluidity. The interaction of heavy metals with cellular membranes may contribute to explain, at least partially, the toxicity associated with these metals.

Cell Membrane↗
PubMed2005

Human immunodeficiency virus 1 (HIV-1) envelope-dependent cell-cell fusion modulation by HIV-positive sera is related to disease progression.

Fusion of CD4+ cells by HIV-1 envelope proteins (Env) is a mechanism of virus spread and cell damage. Production of antibodies able to influence cell-cell fusion in vivo may affect the course of the infection. The effect of sera from 49 HIV-1-positive patients was tested on an in vitro fusion assay using Env-expressing and normal Jurkat T cells labelled with DiI and DiO dyes, and flow cytometry for quantification of cell-cell fusion. Sera varied in their activity on fusion: 69.4 % inhibited, 24.5 % had no effect and 6.1 % enhanced cell fusion. Fusion activity correlated positively with the CD4+ T-cell count and inversely with the viral load. Removal of IgG or IgM from sera reduced or eliminated inhibition and enhancing activities, respectively. Antibodies with inhibitory activity predominate in early and intermediate stages of infection, whereas loss of inhibition or enhancement of fusion correlates with progression to AIDS.

Cell Fusion↗
PubMed2005

Nosocomial transmission of Mycobacterium tuberculosis in a children's hospital.

An infant was admitted for evaluation of respiratory distress and tracheomalacia. After several weeks of hospitalization, both the infant and her mother were diagnosed with culture-positive pulmonary tuberculosis (TB). Sixteen pediatric patients and 293 health care workers were evaluated for exposure to Mycobacterium tuberculosis. Tuberculin skin test conversions occurred in 6.7% of patients and 1.9% of pediatric health care workers. While nosocomial transmission of TB is relatively rare in children's hospitals, this report highlights the differences between TB control efforts in pediatric vs. adult facilities, including the importance of screening the adult visitors of children admitted with suspected TB.

Contact Tracing↗
PubMed2001

Effect of 4-trifluoromethyl derivatives of salicylate on nuclear factor kappaB-dependent transcription in human astrocytoma cells.

1. The effect of two derivatives of salicylate, 2-hydroxy-4-trifluoromethylbenzoic acid (HTB) and 2-acetoxy-4-trifluoromethylbenzoic acid (triflusal), on the expression of several proteins displaying pro-inflammatory activities the regulation of which is associated to the transcription factor NF-kappaB, was assayed in the human astrocytoma cell line 1321N1. 2. Tumour necrosis factor-alpha (TNF-alpha) activated NF-kappaB as judged from both the appearance of kappaB-binding activity in the nuclear extracts, the degradation of IkappaB proteins in the cell lysates, and the activation of IkappaB kinases using an immunocomplex kinase assay with glutathione S-transferase (GST)-IkappaB proteins as substrates. 3. HTB up to 3 mM did not inhibit the nuclear translocation of NK-kappaB/Rel proteins as judged from electrophoretic mobility-shift assays; however, HTB inhibited the degradation of IkappaBbeta without significantly affecting the degradation of both IkappaBalpha and IkappaBepsilon. 4. In keeping with their inhibitory effect on IkappaBbeta degradation in the cell lysates, both HTB and triflusal inhibited the phosphorylation of GST-IkappaBbeta elicited by TNF-alpha, without affecting the phosphorylation of GST-IkappaBalpha. 5. The effect of both HTB and triflusal on kappaB-dependent trans-activation was studied by assaying the expression of both cyclo-oxygenase-2 (COX-2) and vascular cell adhesion molecule-1 (VCAM-1). HTB and triflusal inhibited in a dose-dependent manner the expression of COX-2 and VCAM-1 mRNA and the induction of COX-2 protein at therapeutically relevant concentrations. 6. These findings show the complexity of the biochemical mechanisms underlying the activation of NF-kappaB in the different cell types and extend the anti-inflammatory effects of HTB and triflusal to neural cells.

Astrocytoma↗
PubMed2000

Specific subgroup B adenovirus diagnosis by PCR of the fibre gene.

OBJECTIVE: A highly sensitive and specific PCR assay targeting regions of the fibre gene was developed for the identification of subgroup B adenovirus strains. This is critical, since these adenovirus strains are frequently associated with severe respiratory infections in infants and new-borns. METHODS: Clinical samples from nasopharyngeal aspirates were analysed by PCR using several sets of primers corresponding to sequences of the gene coding for the fibre protein. RESULTS: The assay allowed the detection and identification of all the genotypes of adenovirus subgroup B, based on the size of the amplified product when analysed on polyacrilamide gel electrophoresis. Specifically, one set of primers was able to amplify DNA of subgroup B but not subgroup C and E viruses. CONCLUSION: The detection of adenovirus and the genotyping can be done on a routine basis by a PCR assay using the fibre gene as a target. The assay allows the identification of ADV subgroup B, including genotype 7h, which is the single most important viral pathogen associated with respiratory diseases in infants and young children in the southern part of South America.

Adenovirus Infections, Human↗
PubMed1999

Distribution of lithium in different CNS areas and other tissues of adult male and female vizcacha (Lagostomus maximus maximus).

In a previous study (1) we demonstrated that lithium administration (1.0 mmol/kg b.wt., per day for 4 weeks) in intact vizcacha (Lagostomus maximus maximus) leads to significant histological alterations in the kidneys, ovarie and testicles, while these three tissues were not damaged in rats. Male vizcachas died within 4 days when administered LiCl 3 mmol/kg b.wt., while females were not affected. The lithium renal clearance presented no changes in either males or females. The 1.0 mmol/kg b.wt. dose was used in the experiments (2). In this study we examined the distribution of lithium in various tissues of male and female vizcacha (Lagostomus maximus maximus) administered LiCl by injection (1 mmol/kg b.wt.) for one day (Group I) and thirty days (Group II). Blood sample was obtained after 24 hours (Group I) and 30 days (Group II). The tissues investigated were: pituitary, hypothalamus, cerebral cortex, cerebellum, corpus callous, small and large intestine, kidney and suprarenal. The concentration of lithium in tissues and serum was determined by atomic absortion spectrometry (3,4). In Group I a significant lithium concentration increment (mumol/g of tissue) was observed in all the tissues of male vizcachas as compared to female vizcacha. A similar distribution was obtained in animals treated for 30 days. In the pituitary, however this difference between males and females was not significant. The male lithium serum levels were significantly higher than those of female animals. In conclusion, we suggest that the particular structure of the cell membrane (e.g., number and characteristic of sodium channels) of each tissue and/or the intracellular mechanisms of transport, elimination and metabolism might explain the unequal lithium distribution and the difference recovery from the damage produced. The results suggest that the vizcacha could be a useful model for the study of lithium toxicity.

Adrenal Glands↗
PubMed1986

Ecological study of Rocky Mountain spotted fever in Costa Rica.

Since Rocky Mountain spotted fever (RMSF) was recognized in Costa Rica, ecological studies have been undertaken to discern its distribution and the natural cycle of Rickettsia rickettsii. The population of ticks parasitizing animals and vegetation was scarce. Rickettsiae were not isolated from pools of ticks nor from spleens of the animals studied. However, the active circulation of rickettsiae was evidenced through the demonstration of spotted fever group antibodies in humans, dogs, and wild rabbits. These findings concur with those in a number of fatal human cases as well as with the isolation of R. rickettsii from wild rabbit ticks.

Animals↗
PubMed1985

Isolation and identification of Rickettsia rickettsii from the rabbit tick (Haemaphysalis leporispalustris) in the Atlantic zone of Costa Rica.

During the ecological studies done in Costa Rica on Rocky Mountain spotted fever, we have been able to isolate 2 strains of rickettsiae from the rabbit tick Haemaphysalis leporispalustris, indistinguishable from R. rickettsii isolated from humans in our country. Moreover, serological evidence of this agent was demonstrated in convalescent guinea pigs and in the sera of the wild rabbit (Sylvilagus braziliensis).

Animals↗