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Biomedical subjects

Javier García

Publications and source records attributed to Javier García.

At least 19 recordsLinked to original sources
PubMed2006

New concept for the separation of an anomeric mixture of alpha/beta-D-nucleosides through regioselective enzymatic acylation or hydrolysis processes.

An efficient and high yield protocol for the synthesis and separation of 3'- and/or 5'-protected alpha-2'-deoxynucleosides has been developed through regioselective acylation/deacylation processes catalyzed by enzymes. Pseudomonas cepacia lipase (PSL-C) was found to be highly chemo- and regioselective toward the 3'-position of the beta-2'-deoxynucleoside derivatives, whereas PSL-C displayed opposite selectivity toward the 5'-position for the corresponding alpha-anomer. The successful application of this protocol was demonstrated by a convenient separation of an alpha/beta-mixture of thymidine derivatives from an industrial waste stream. Furthermore, this technique was also applied for the separation of an anomeric mixture of 2'-deoxy-2'-fluoro-alpha/beta-arabinonucleosides that are useful building blocks for the antisense constructs.

Acylation↗
PubMed2006

Renal pro-inflammatory cytokine gene expression in diabetic nephropathy: effect of angiotensin-converting enzyme inhibition and pentoxifylline administration.

BACKGROUND: Recent studies have shown a role for inflammation in the pathogenesis of diabetic nephropathy (DN). Tumor necrosis factor (TNF)-alpha, interleukin (IL)-1 and IL-6 are cytokines with a prevalent pro-inflammatory activity. Our objective was to study the renal gene expression of TNF-alpha, IL-1 and IL-6 in DN and their relationship with renal damage assessed by urinary albumin excretion (UAE). In addition, we also investigated the effect of angiotensin-converting enzyme inhibition and pentoxifylline (PTF) administration on these parameters. METHODS: After streptozotocin-induced diabetes, rats received either no treatment or therapy with enalapril (EN) or PTF for 8 weeks. Renal expression of pro-inflammatory cytokines was evaluated by real-time polymerase chain reaction. Urinary cytokine excretion and albuminuria were also evaluated. RESULTS: Renal cortical mRNA expression for TNF-alpha, IL-1 and IL-6 in untreated diabetic rats was 2.4-, 1.2- and 3.4-fold higher than in non-diabetic rats. Kidney weight and UAE were significantly associated with renal mRNA expression of TNF-alpha and IL-6. Both EN and PTF administration virtually abrogated the overexpression of TNF-alpha, IL-1 and IL-6, which was associated with a reduction in kidney weight and urinary albumin excretion. CONCLUSION: The renal expression of the main pro-inflammatory cytokines TNF-alpha, IL-1 and IL-6 is increased in DN, which is significantly associated with UAE. EN and PTF administration prevented this enhanced expression, leading to a decrease in urinary cytokine excretion and a reduction in albuminuria. These findings provide novel insight into the pathogenic mechanisms of DN, supporting the hypothesis that inflammatory mechanisms play a role in the renal injury secondary to diabetes mellitus.

Albuminuria↗
PubMed2006

Joint transform correlator with spatial code division multiplexing.

A joint transform correlator may suffer from overlapping of the zero diffraction order of the output, which does not contain relevant information, and the correlation peaks that appear in the first diffraction orders if objects are not sufficiently separated. Such overlapping significantly reduces the signal-to-noise ratio of the identification process. We propose a novel approach based on code division multiplexing technique in which the contrast of the identification peaks is significantly enhanced. The approach does not include placing the two objects side by side but rather includes code multiplexing them. Moreover, the code division multiplexing technique allows the space-bandwidth product to be improved. Optical implementation results are given.

Journal Article↗
PubMed2006

Urinary tumour necrosis factor-alpha excretion independently correlates with clinical markers of glomerular and tubulointerstitial injury in type 2 diabetic patients.

BACKGROUND: Inflammation is a potential factor in the development and progression of diabetic nephropathy. The aim of this study was to analyse the relationship between the pro-inflammatory cytokine tumour necrosis factor-alpha (TNFalpha) and clinical markers of glomerular and tubulointerstitial damage [urinary albumin excretion (UAE) and urinary N-acetyl-beta-glucosaminidase (UNAG), respectively] in a large group of type 2 diabetic patients. METHODS: A total of 160 diabetic patients and 32 healthy controls were included in the study. High-sensitive C-reactive protein (hs-CRP) as well as serum and urinary levels of TNFalpha were measured. UAE and UNAG were determined by 24-h urine collection. RESULTS: Serum hs-CRP and TNFalpha were significantly higher in diabetic than in control subjects, as well as UAE and UNAG. Diabetic patients had increased urinary TNFalpha compared to non-diabetics [14.5 (2-29) vs 4 (0.8-12), P < 0.001]. Serum hs-CRP and TNFalpha in diabetics with increased UAE were elevated compared to diabetics having normoalbuminuria. Urinary TNFalpha was also higher in diabetic subjects with micro- or macroalbuminuria than in patients with normal UAE [10.5 (4-20) and 18 (9-29) vs 7 (2-18) pg/mg, P < 0.0001, respectively]. Multiple regression analysis showed that urinary TNFalpha (P < 0.0001), hs-CRP (P < 0.0001), serum TNFalpha (P < 0.01) and HbA1c (P < 0.05) were independent of and significantly associated with UAE, whereas duration of diabetes (P < 0.001), urinary TNFalpha (P < 0.01), HbA1c (P = 0.01), hs-CRP (P < 0.05) and serum creatinine (P < 0.05) were associated with UNAG. CONCLUSIONS: In patients with type 2 diabetes, urinary TNFalpha excretion is elevated and correlates with severity of renal disease in terms of both glomerular and tubulointerstitial damage, suggesting a significant role for TNFalpha in the pathogenesis and progression of renal injury in diabetes mellitus.

Biomarkers↗
PubMed2006

Three-dimensional object detection under arbitrary lighting conditions.

A novel method of 3D object recognition independent of lighting conditions is presented. The recognition model is based on a vector space representation using an orthonormal basis generated by the Lambertian reflectance functions obtained with distant light sources. Changing the lighting conditions corresponds to multiplying the elementary images by a constant factor and because of that, all possible lighting views will be elements that belong to that vector space. The recognition method proposed is based on the calculation of the angle between the vector associated with a certain illuminated 3D object and that subspace. We define the angle in terms of linear correlations to get shift and illumination-invariant detection.

Algorithms↗
PubMed2006

Plasmodium falciparum merozoite surface protein 6 (MSP-6) derived peptides bind erythrocytes and partially inhibit parasite invasion.

This work shows that Plasmodium falciparum merozoite surface protein-6 (MSP-6) peptides specifically bind to membrane surface receptor on human erythrocytes. Three high activity binding peptides (HABPs) were found: peptides 31175 (41MYNNDKILSKNEVDTNIESN60) and 31178 (101YDIQATYQFPSTSGGNNVIP120) in the amino terminal region and 31191 (361EIDSTINNLVQEMIHLFSNNY380) at the carboxy terminal. Their binding to erythrocytes was saturable. HABPs 31191 and 31178 recognized 56 and 26 kDa receptors on erythrocyte membrane and inhibited in vitro Plasmodium falciparum merozoite invasion of erythrocytes by between 27% and 46% at 200 microg ml(-1) concentration, suggesting that these MSP-6 protein peptides play a possible role in the invasion process.

Amino Acid Sequence↗
PubMed2006

Isolation of human serum immunoglobulins with a new salt-promoted adsorbent.

In this work a highly acetylated-ethylenediamine-Novarose (HA-EDA-Novarose) gel was synthesized and used as a new agarose-based salt-promoted adsorption chromatography (SPAC) matrix to effectively isolate serum immunoglobulins without the need of denaturing conditions. Samples of human serum in 0.5 M Na2SO4, 10 mM 3-(N-morpholino)-propane-sulfonic acid (MOPS), pH 7.6 were applied to a chromatographic column packed with the SPAC gel. Immunoglobulins (Igs) with affinity for the HA-EDA ligands were specifically adsorbed to the matrix, non-bound serum proteins were readily removed by washing the column with the same feed solution buffer. Bound Igs were effectively and very gently eluted by simply removing the salt from the feed solution buffer. The elution buffer consisted thus of only 10 mM MOPS, at pH 7.6 and no salt. The salt-dependent adsorption capacity of this system was estimated to be 7.3 mg/ml with protein recovery of about 93%. Sodium dodecyl sulfate-polyacrylamide gel (SDS-PAGE) electrophoresis analysis, radial immunodiffusion and enzyme-linked immunosorbent assays showed that immunoglobulins G, M and A (IgG, IgM and IgA) were the main components present in the elution fraction. The new SPAC adsorbent was used to purify Igs from human serum and IgG and IgA from non-pure commercially available Igs preparations in a very gentle single step.

Adsorption↗
PubMed2006

Superresolved imaging of remote moving targets.

We present a superresolving approach that allows one to exceed the diffraction limit and recover highly resolved contours of moving targets from a sequence of low-resolution images. The presented approach is suitable for remote sensing applications. The resolution decoding algorithm that is used to recover the high-resolution features of the target can be run partially via optical means and that way can be used to reduce the required computational complexity.

Algorithms↗
PubMed2006

Superresolved imaging in digital holography by superposition of tilted wavefronts.

A technique based on superresolution by digital holographic microscopic imaging is presented. We used a two dimensional (2-D) vertical-cavity self-emitting laser (VCSEL) array as spherical-wave illumination sources. The method is defined in terms of an incoherent superposition of tilted wavefronts. The tilted spherical wave originating from the 2-D VCSEL elements illuminates the target in transmission mode to obtain a hologram in a Mach-Zehnder interferometer configuration. Superresolved images of the input object above the common lens diffraction limit are generated by sequential recording of the individual holograms and numerical reconstruction of the image with the extended spatial frequency range. We have experimentally tested the approach for a microscope objective with an exact 2-D reconstruction image of the input object. The proposed approach has implementation advantages for applications in biological imaging or the microelectronic industry in which structured targets are being inspected.

Journal Article↗
PubMed2006

Determination of foscarnet (trisodium phosphonoformate) in pharmaceutical preparations by high-performance liquid chromatography with ultraviolet detection.

An isocratic high-performance liquid chromatographic method with UV detection has been developed and validated for the quantitative determination of foscarnet in isoosmotic sodium chloride aqueous solution. The mobile phase consisted of mixture of methanol:water (30:70 v/v), containing 1 mm tetrahexylammonium hydrogen sulphate at pH 5.80. The analyte was separated on a reversed-phase C(18) column packed with 4 microm spherical particles of octadecylsilane. Hydrochlorothiazide was used as internal standard. UV detection at 232 nm allowed a quantification limit of 50 microg/mL. The assay was linear from 50 to 4000 microg/mL. The coefficient of variation was < or =2.52% for intra-assay precision and < or =3.49% for inter-assay precision. The deviation from the nominal value ranged from -0.57 to 0.47% for the same-day accuracy and from -0.75 to 3.06% for day-to-day accuracy.

Chromatography, High Pressure Liquid↗
PubMed2006

Synthetic aperture superresolution with multiple off-axis holograms.

An optical setup to achieve superresolution in microscopy using holographic recording is presented. The technique is based on off-axis illumination of the object and a simple optical image processing stage after the imaging system for the interferometric recording process. The superresolution effect can be obtained either in one step by combining a spatial multiplexing process and an incoherent addition of different holograms or it can be implemented sequentially. Each hologram holds the information of each different frequency bandpass of the object spectrum. We have optically implemented the approach for a low-numerical-aperture commercial microscope objective. The system is simple and robust because the holographic interferometric recording setup is done after the imaging lens.

Journal Article↗
PubMed2006

[Influence of shear stress on in-stent restenosis: in vivo study using 3D reconstruction and computational fluid dynamics].

INTRODUCTION AND OBJECTIVES: Local factors may influence neointimal proliferation following conventional stent implantation. In this study, the relationship between wall shear stress and luminal loss after coronary stenting was assessed using a combination of angiography, intravascular ultrasound, and computational fluid dynamics. PATIENTS AND METHOD: Seven patients with de novo right coronary lesions treated with conventional (i.e., bare metal) stents were included. Realistic three-dimensional geometric reconstructions were generated offline from angiographic and intravascular ultrasound data both immediately after stenting and at 6-month follow-up. A finite-volume model was used to calculate local wall shear stress within the stent and 4 mm proximally and distally to the stent. The mean coronary ostium entry flow velocity was assumed to be 25 cm/s in all cases. RESULTS: The mean neointimal thickness was 0.29 (0.21) mm. In five cases, weak negative correlations between wall shear stress and neointimal thickness were found: maximum r value = -0.34, minimum r value = -0.11 (P < .001). The neointimal thickness in segments in which the level of wall shear stress was in the lowest quartile was greater than that in segments in which it was in highest quartile, at 0.34 (0.21) mm and 0.27 (0.24) mm (P < .001) for quartiles 1 and 4, respectively. CONCLUSIONS: Low wall shear stress after stenting favors neointimal proliferation both within the stent and at the stent's edges.

Adult↗
PubMed2005

Spatial information transmission using orthogonal mutual coherence coding.

We use the coherence of a light beam to encode spatial information. We apply this principle to obtain spatial superresolution in a limited aperture system. The method is based on shaping the mutual intensity function of the illumination beam in a set of orthogonal distributions, each one carrying the information for a different frequency bandpass or spatial region of the input object. The coherence coding is analogous to time multiplexing but with multiplexing time slots that are given by the coherence time of the illumination beam. Most images are static during times much longer than this coherence time, and thus the increase of resolution in our system is obtained without any noticeable cost.

Journal Article↗
PubMed2005

Identifying putative Mycobacterium tuberculosis Rv2004c protein sequences that bind specifically to U937 macrophages and A549 epithelial cells.

Virulence and immunity are still poorly understood in Mycobacterium tuberculosis. The H37Rv M. tuberculosis laboratory strain genome has been completely sequenced, and this along with proteomic technology represent powerful tools contributing toward studying the biology of target cell interaction with a facultative bacillus and designing new strategies for controlling tuberculosis. Rv2004c is a putative M. tuberculosis protein that could have specific mycobacterial functions. This study has revealed that the encoding gene is present in all mycobacterium species belonging to the M. tuberculosis complex. Rv2004c gene transcription was observed in all of this complex's strains except Mycobacterium bovis and Mycobacterium microti. Rv2004c protein expression was confirmed by using antibodies able to recognize a 54-kDa molecule by immunoblotting, and its location was detected on the M. tuberculosis surface by transmission electron microscopy, suggesting that it is a mycobacterial surface protein. Binding assays led to recognizing high activity binding peptides (HABP); five HABPs specifically bound to U937 cells, and six specifically bound to A549 cells. HABP circular dichroism suggested that they had an alpha-helical structure. HABP-target cell interaction was determined to be specific and saturable; some of them also displayed greater affinity for A549 cells than U937 cells. The critical amino acids directly involved in their interaction with U937 cells were also determined. Two probable receptor molecules were found on U937 cells and five on A549 for the two HABPs analyzed. These observations have important biological significance for studying bacillus-target cell interactions and implications for developing strategies for controlling this disease.

Amino Acid Sequence↗
PubMed2005

Additive antiproteinuric effect of pentoxifylline in patients with type 2 diabetes under angiotensin II receptor blockade: a short-term, randomized, controlled trial.

Despite the beneficial effects of blockade of the renin-angiotensin system in diabetic nephropathy (DN), albuminuria and progression of renal disease are not completely halted by these agents. Therefore, it is necessary to explore potential antiproteinuric and renoprotective effects of innovative therapeutic approaches. This study tested the hypothesis that the combination of pentoxifylline (PTF) with angiotensin II receptor blockers in normotensive patients with type 2 diabetes produces an additive antiproteinuric effect. Sixty-one patients with DN and residual albuminuria despite treatment with the recommended doses of ARB for >1 yr were randomly assigned to receive the addition of 1200 mg of PTF daily (n = 30) or to a control group (n = 31). Baseline characteristics were similar between groups, and correlation analysis showed a significant association between urinary albumin excretion (UAE) and urinary TNF-alpha (R = 0.53, P < 0.001). After 4 mo, albuminuria showed a significant decrease in patients who received PTF, from 900 mg/24 h (466 to 1542 mg/d) to 791 mg/24 h (309 to 1400 mg/d; P < 0.001), whereas no significant changes were observed in the control group: 920 mg/24 h (450 to 1489 mg/d) at baseline, and 900 mg/24 h (428 to 1800 mg/d) at the end of the study. The mean percentage variation of UAE in the treatment and control groups was -16.7 and 5.5%, respectively (between-group comparison, P < 0.001). This additive antiproteinuric effect was not dependent on changes in BP or metabolic control. However, both serum and urinary levels of TNF-alpha also decreased in patients who received PTF, from 6.4 pg/ml (2.1 to 9.7) and 16 pg/mg (8 to 29) at baseline to 4.6 pg/ml (0.4 to 9) and 14.2 pg/mg (3 to 26) at the end of the study, respectively (P < 0.01), without significant variations in control patients. Moreover, regression analysis at the end of the study showed a correlation between the change in UAE and the change in urinary TNF-alpha in patients who were treated with PTF (R = 0.49, P < 0.001). In conclusion, administration of PTF to patients who have type 2 diabetes and are under long-term treatment with an ARB produces a significant additive antiproteinuric effect associated with a reduction of urinary TNF-alpha excretion.

Aged↗
PubMed2005

Identifying Plasmodium falciparum merozoite surface protein-10 human erythrocyte specific binding regions.

Receptor-ligand interactions between synthetic peptides and normal human erythrocytes were studied to determine P. falciparum merozoite surface protein-10 (MSP-10) regions specifically binding to membrane surface receptors on human erythrocytes. Three MSP-10 protein High Activity Binding Peptides (HABPs) were identified, whose binding to erythrocytes became saturable and sensitive on being treated with neuraminidase, trypsin and chymotrypsin. Some of them specifically recognised a 50 kDa erythrocyte membrane protein. Some HABPs inhibited in vitro P. falciparum merozoite invasion of erythrocytes by 70%, suggesting that MSP-10 protein's possible role in the invasion process probably functions by using similar mechanisms to those described for other MSP family antigens. In addition to above results, the high homology in amino-acid sequence and superimposition of both MSP-10, MSP-8 and MSP-1 EGF-like domains and HABPs 31132, 26373 and 5501 suggest that tridimensional structure could be playing an important role in the invasion process and in designing synthetic multi-stage anti-malarial vaccines.

Amino Acid Sequence↗
PubMed2005

Mycobacterium tuberculosis Rv2536 protein implicated in specific binding to human cell lines.

The gene encoding the Mycobacterium tuberculosis Rv2536 protein is present in the Mycobacterium tuberculosis complex (as assayed by PCR) and transcribed (as determined by RT-PCR) in M. tuberculosis H37Rv, M. tuberculosis H37Ra, M. bovis BCG, and M. africanum strains. Rabbits immunized with synthetic polymer peptides from this protein produced antibodies specifically recognizing a 25-kDa band in mycobacterial sonicate. U937 and A549 cells were used in binding assays involving 20-amino-acid-long synthetic peptides covering the whole Rv2536 protein sequence. Peptide 11207 (161DVFSAVRADDSPTGEMQVAQY180) presented high specific binding to both types of cells; the binding was saturable and presented nanomolar affinity constants. Cross-linking assays revealed that this peptide specifically binds to 50 kDa U937 cell membrane and 45 kDa A549 cell membrane proteins.

Amino Acid Sequence↗