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V Rodriguez

Publications and source records attributed to V Rodriguez.

At least 19 recordsLinked to original sources
PubMed2006

Significant enhancement of the optical second harmonic generation in a poled azopolymer thin grating.

Nonlinear optical properties of an electrically poled surface relief grating inscribed on a thin film of azopolymer have been investigated. The linear and nonlinear optical far-field diffraction patterns of the grating are compared, and they show a clear angular separation of the fundamental (lambda = 1.064 mum) and second harmonic generated beams that are diffracted at different angles. The intensity of the zero order transmitted second harmonic generation (SHG) beam from inscribed surface relief grating (SRG) areas has been recorded using the Maker fringe technique and compared to the response from flat areas that were only poled. Poled gratings exhibit a sharp second harmonic generation enhancement for coupling angles of theta(i) = +/-52 degrees due to a quasi-phase matching process. A simple phenomenological model allows one to explain both the second harmonic intensity generated from the thin polar film and the dispersion curve observed under "pp" polarization due to the mismatch of the angular coupling condition: this gives us a good indication of the intensity enhancement of the SHG beam in the forward direction.

Letter↗
PubMed2006

Use of prophylactic anticoagulation and the risk of hepatic veno-occlusive disease in patients undergoing hematopoietic stem cell transplantation: a systematic review and meta-analysis.

Hepatic veno-occlusive disease is a serious regimen-related toxicity in patients undergoing hematopoietic stem cell transplantation. We performed a systematic review and meta-analysis of the literature on the effect of anticoagulation in preventing veno-occlusive disease. Several databases and online journals were searched for randomized controlled trials and cohort studies. Twelve studies (2782 patients) were eligible. Anticoagulation prophylaxis was associated with a statistically nonsignificant decrease in risk of veno-occlusive disease (pooled relative risk (RR), 0.90; 95% confidence interval (CI), 0.62-1.29). Results of one of three randomized controlled trials may have been affected by delayed introduction of anticoagulation. A second trial enrolled patients who received conventional chemoradiotherapy for early-stage disease (RR, 0.18; 95% CI, 0.04-0.78). The third trial was a pilot study with a small sample size (RR, 0.74; 95% CI, 0.53-1.04). Significant heterogeneity and methodologic weaknesses preclude drawing a meaningful conclusion from the pooled analysis. Despite some limitations, results of two of three eligible randomized controlled trials suggest that prophylactic anticoagulation may help prevent veno-occlusive disease. However, a large randomized controlled trial is needed for confirmation. Additionally, in future studies, owing to the wide spectrum of severity of veno-occlusive disease, outcomes such as 100-day mortality should strongly be considered.

Anticoagulants↗
PubMed2005

Contamination of the nebulization systems used in the prophylaxis with amphotericin B nebulized in lung transplantation.

The contamination of nebulizer may be the origin of respiratory infections. The aim of this study was to determine the incidence of contamination in nebulizers used to nebulize amphotericin B in lung transplant (LT) patients and the relationship with bacterial isolation in sputum culture. A prospective, cross-sectional study was conducted with 41 LT patients who were administered amphotericin B with a jet nebulizer. Samples were taken from the nebulizers (prior to nebulization). Sputum culture was carried out and patients were asked whether or not they followed a cleaning and disinfection protocol (washing and brushing with soap and water followed by subsequent disinfection with the Milton method after each nebulization). Contamination was defined as such when potentially pathogenic bacteria were isolated in the nebulizer. Seventeen of the 41 nebulizers (41.4%) were contaminated. In 7 of the 17 cases (41.1%) contamination was polymicrobial. The most common microorganism was Pseudomonas aeruginosa. Fourteen of the 41 patients (34.1%) presented positive sputum cultures, most common was P aeruginosa. In 10 patients (24.3%) pathogenic bacteria was isolated both in the nebulizer and in the sputum. In four of these patients (9.7%) the species was the same. The cleaning and disinfection protocol was carried out by 16 of the 41 patients (39.0%). In 2 of the 16 patients (12.5%) who were following the protocol the nebulizer was contaminated, compared to 15 of 25 patients (60.0%) whose nebulizer was not contaminated (P < .05). Two of the 16 patients (12.%) who were following the protocol presented positive sputum culture compared to 12 of 25 (48.0%) who did not (P < .05). In conclusion, the contamination of the nebulizing systems is frequent when no strict cleaning and disinfection protocol is followed. Patients who did not follow the protocol presented a greater isolation of pathogenic bacteria in the sputum.

Amphotericin B↗
PubMed2005

Intracranial haemorrhage as initial presentation of severe haemophilia B: case report and review of Mayo Clinic Comprehensive Hemophilia Center experience.

A neonate who had intracranial haemorrhage (ICH) at birth received a diagnosis of severe haemophilia B at 6 months of age. ICH had been the initial presentation of his bleeding disorder. His family history was negative for haemophilia. Review of our institutional experience as well as the literature indicates that intracranial bleeding as the initial presentation of haemophilia is rare.

Factor IX↗
PubMed2005

Clindamycin-resistant Fusobacterium varium bacteremia and decubitus ulcer infection.

Bacteremia due to Fusobacterium spp. is unusual (<10% of cases of anaerobic bacteremia), and the isolation of Fusobacterium varium is especially uncommon. The most probable sources of Fusobacterium bacteremia are the respiratory, the gastrointestinal, and the genitourinary tracts. A.-M. Bourgault et al. (Clin. Infect. Dis. 25[Suppl. 2]:181-183) described 40 patients with Fusobacterium bacteremia; only 3 had Fusobacterium varium, and no one had decubitus scars as the portal of entry. In another published series (S. Henry, A. De Maria, and W. R. McCabe, Am. J. Med. 75:225-231, 1983) of 26 cases, two patients had concomitant pulmonary lesions and decubitus ulcers but there was no identification to the species level mentioned. We report a case of Fusobacterium varium bacteremia and infected sacral decubitus ulcer in an elderly patient.

Aged↗
PubMed2005

Orientation distribution functions based upon both (P1), (P3) order parameters and upon the four (P1) up to (P4) values: application to an electrically poled nonlinear optical azopolymer film.

The most probable orientational distribution functions of rod-like polar molecules contained in a noncentrosymmetric uniaxial system are established using the first-rank and third-rank Legendre polynomials, (P1(cos theta)) and (P3(cos theta)) order parameters, and the maximum entropy method. Emphasis is put on the different domains of existence in the ((P1), (P3)) plane for the various shapes of the distributions: it is thus shown that, for any positive (P1(cos theta)) value and for decreasing (P3(cos theta)) values, the distribution function may exhibit either a distorted oblate form with an intense maximum at 0 degrees, or a three-leaved rose curve with maxima at 60 degrees, 180 degrees, and 300 degrees, and finally another markedly oblate shape with a strong maximum at 180 degrees. As an illustrative example, we have considered the azobenzene molecular orientations in an electrically poled p(DR1M) homopolymer thin film after a thermal process and several relaxation periods. We have made use not only of the (P1) and (P3) parameters determined from polarized second-harmonic generation (SHG) measurements, but also of the (P2) values extracted from UV-visible spectra and of the (P4) values adjusted according to the information entropy theory. In such a thin film with very large nonlinear properties (d33 coefficients were varying from 437.0 to 117.0 pm/V at 1064 nm) it is evidenced that a strong polar order is maintained even after a long relaxation period of 42 days. So, the distribution functions demonstrate that the poling treatment was quite efficient and they emphasize the importance in the determination of both couples of odd and even order parameters in such uniaxially oriented optical elements.

Algorithms↗
PubMed2004

Wilms' tumor and neuroblastoma.

Significant differences exist between the European and North American treatment protocols for Wilms' tumor and neuroblastoma. There are variations in biopsy technique, timing and extent of initial surgery, chemotherapy protocols and dosage routines, as well as the type of salvage therapy. With the consolidation of the two major North American study groups into a single entity (Children's Oncology Group), the European and North American study groups represent the only remaining large-scale venues for treatment comparison. It is important to study and understand the variation in treatment protocols in order to maintain an open forum of scientific investigation that will lead to improving the care and outcome of children with cancer. It is anticipated that the unification of the North American groups will lead to greater interest and scientific cooperation with the European study group. This paper will serve as a forum for such a discussion at a local level.

Clinical Protocols↗
PubMed2002

Guillain-Barré syndrome after allogeneic hematopoietic stem cell transplantation.

Guillain-Barré syndrome is a rare complication in the setting of hematopoietic stem cell transplantation. We report three children with T cell lymphoma/leukemia in whom this syndrome developed soon after they received unrelated donor transplants. The rapid onset of symptoms raises the concern that the bone marrow transplant conditioning regimen (ie, total body irradiation, cyclophosphamide and cytosine arabinoside) might have precipitated the clinical syndrome of ascending polyneuropathy. Although central nervous system toxicity has been well described with high-dose cytosine arabinoside therapy, peripheral neuropathy of the Guillain-Barré type has been reported only infrequently. We review possible factors contributing to the development of this syndrome in these three patients.

Adolescent↗
PubMed2002

Haemorrhage into a popliteal cyst: an unusual complication of haemophilia A.

A 7(1/2)-year-old boy with severe haemophilia A had increasing discomfort and pain in his left knee after sledding on ice and landing on his knees. Left knee pain persisted for days despite recombinant factor VIII replacement. Imaging studies showed that by day 10 a popliteal cyst had ruptured, with diffusion of blood into the calf muscles. This case illustrates another possible bleeding complication in patients with a bleeding disorder and a popliteal cyst.

Accidental Falls↗
PubMed2001

Essential role of the conformational flexibility of helices 1 and 5 on the lipid binding activity of apolipophorin-III.

It has been recently postulated that the conformational flexibility of helices 1 and 5 of Locusta migratoria apoLp-III could play an important role in early steps of binding of this apolipoprotein to a lipid surface (Soulages, J. L., and Arrese, E. L. (2000) J. Biol. Chem. 275, 17501-17509). To test this model, we have designed a double Cys mutant in which a disulfide bond linking helices 1 and 5 could be formed, resulting in an apolipoprotein with reduced conformational flexibility of its N- and C-terminal helices. Substitution of Thr(18) and Ala(147) by Cys residues provided a protein that under nonreducing conditions was fully oxidized. The far-UV CD spectra of this mutant in the reduced and oxidized states indicated that their secondary structures were identical to the structure of the wild type recombinant apoLp-III, which contains no Cys residues. Near-UV CD studies confirmed the formation of a disulfide bond and the absence of structural perturbations. The lipid binding activity of the reduced mutant, as determined by its ability to form discoidal lipoproteins, was nearly identical to that of the wild type protein. Contrarily, the disulfide form of the mutant was not able to form discoidal lipoproteins with liposomes of either dimirystoylphosphatidylcholine or dimyristoylphosphatidylglycerol. It is concluded that the separation of the helices 1 and 5 constitutes one of the key steps along the complex pathway for the formation of the final apolipoprotein lipid-bound state. It is inferred that the conformational flexibility of helices 1 and 5 is a key property of apoLp-III, allowing the exposure of hydrophobic protein regions and the interaction of the hydrophobic faces of the amphipathic alpha-helices with the lipoprotein lipid surface.

Animals↗
PubMed2000

Major liver resection for carcinoma in jaundiced patients without preoperative biliary drainage.

BACKGROUND: The role of preoperative biliary drainage (PBD) before liver resection in the presence of obstructive jaundice remains controversial. Our patients with proximal duct carcinoma undergo noninvasive assessment followed by rapid laparotomy without PBD if the lesion is deemed resectable. HYPOTHESIS: Our aim was to report operative outcome of these patients and to analyze their specific features by comparison with patients without biliary obstruction who underwent major liver resection. DESIGN: A case-comparison study. SETTING: A tertiary care university hospital in a metropolitan area. PATIENTS: Twenty consecutive jaundiced patients underwent major liver resection without PBD. The jaundiced patients were matched with 27 nonjaundiced patients with normal underlying liver selected from a computer bank of 261 patients undergoing liver resections and identical for age, tumor size, type of liver resection, and vascular occlusion. MAIN OUTCOME MEASURE: Postoperative course including mortality, morbidity, transfusion rates, and results of liver function tests. RESULTS: Seventeen jaundiced patients (85%) and 13 nonjaundiced patients (48%) received blood transfusions (P = .03). Morbidity was 50% in jaundiced and 15% in nonjaundiced patients (P = .006), mainly resulting from subphrenic collections and bile leaks occurring only in jaundiced patients. In contrast, there were no significant differences for mortality (5% vs 0%) and liver failure (5% vs 0%). Postoperative changes in liver function test results were comparable between groups. CONCLUSIONS: Major liver resections without PBD are safe in most patients with obstructive jaundice. Recovery of hepatic synthetic function is identical to that of nonjaundiced patients. Transfusion requirements and incidence of postoperative complications, especially bile leaks and subphrenic collections, are higher in jaundiced patients. Whether PBD could improve these results remains to be determined.

Adult↗
PubMed2000

Microwave ablation using a spiral antenna design in a porcine thigh muscle preparation: in vivo assessment of temperature profile and lesion geometry.

INTRODUCTION: Theoretical studies have suggested that microwave energy can increase the depth of heating compared with radiofrequency energy. A spiral microwave antenna design may have advantages over previous designs using smaller designs because the resulting power deposition pattern is considerably larger than the catheter diameter. We tested the efficacy of a spiral antenna using microwave energy in a porcine thigh muscle preparation. METHODS AND RESULTS: In five anesthetized pigs, the thigh muscle was exposed and bathed in heparinized bovine blood (36 degrees to 37 degrees C). A helical microwave catheter with a fiberoptic thermometer attached to the distal end was positioned perpendicular to the thigh muscle. The antenna-tissue interface and tissue temperatures at depths of 3.0 and 6.0 mm were measured. A 915-MHz microwave generator delivered energy at one of three power outputs (50, 100, or 150 W) for 60 seconds. Seventy lesions were created: 50 W (n = 23), 100 W (n = 24), and 150 W (n = 23). The mean depths at 50, 100, and 150 W were 4.3 +/- 1.8 mm, 7.2 +/- 1.7 mm, and 9.4 +/- 0.9 mm, respectively. Lesion depth (R = 0.96, P = 0.05), maximum surface dimension (R = 0.99, P = 0.06), and volume (R = 0.99, P = 0.04) were closely correlated to the power applied. CONCLUSION: Power is an important determinant of lesion size using a spiral microwave antenna. A novel, spiral microwave antenna design can create lesions of significant depth that may be applicable for the ablative therapy of ventricular tachycardia.

Animals↗
PubMed2000

Isolation of mycobacteria from frozen fish destined for human consumption.

Mycobacteria were isolated from defrost water and tissue of sole (Solea solea), hake (Merluccius merluccius), cod (Gadus morhua), ling (Genypterus blacodes), and monkfish (Lophius piscatorius) on Löwenstein-Jensen medium after incubation at different temperatures. Samples of frozen fish were obtained under sterile conditions inside a refrigeration chamber (-18 to -22 degrees C) in a wholesale market from which these products are distributed to shops for retail sale and human consumption.

Animals↗
PubMed1999

Testing non-linearity and directedness of interactions between neural groups in the macaque inferotemporal cortex.

Information processing in the visual cortex depends on complex and context sensitive patterns of interactions between neuronal groups in many different cortical areas. Methods used to date for disentangling this functional connectivity presuppose either linearity or instantaneous interactions, assumptions that are not necessarily valid. In this paper a general framework that encompasses both linear and non-linear modelling of neurophysiological time series data by means of Local Linear Non-linear Autoregressive models (LLNAR) is described. Within this framework a new test for non-linearity of time series and for non-linearity of directedness of neural interactions based on LLNAR is presented. These tests assess the relative goodness of fit of linear versus non-linear models via the bootstrap technique. Additionally, a generalised definition of Granger causality is presented based on LLNAR that is valid for both linear and non-linear systems. Finally, the use of LLNAR for measuring non-linearity and directional influences is illustrated using artificial data, reference data as well as local field potentials (LFPs) from macaque area TE. LFP data is well described by the linear variant of LLNAR. Models of this sort, including lagged values of the preceding 25 to 60 ms, revealed the existence of both uni- and bi-directional influences between recording sites.

Action Potentials↗
PubMed1999

Epidemiologic aspects of American visceral leishmaniasis in an endemic focus in Eastern Venezuela.

An endemic focus of American visceral leishmaniasis (AVL) in eastern Venezuela has been evaluated in terms of patients (n = 48), immunologic reactivity to Leishmania in household contacts (n = 187) and neighborhood controls (n = 170), detection of Leishmania (L. donovani complex) in dogs and wild animals by the polymerase chain reaction (PCR) and characteristics of the sandfly population. The male:female ratio of patients was 1.18:1; 89.6% were < or =12 years old. Serologic reactivity was significantly higher in household contacts than in controls (P = 0.0008), as was the size of leishmanin reactions in contacts < or =10 years of age (P = 0.0141). Leishmania donovani complex-specific PCRs were positive in dogs, an opossum (Didelphis marsupialis), and a black rat (Rattus rattus). Lutzomyia longipalpis and Lu. evansi, both implicated in the transmission of AVL, were identified among the 386 sand flies examined. These observations provide the bases for an active control program as well as further studies of reservoirs and vector-host relationships in this area.

Adolescent↗
PubMed1998

European retirees on the Costa del Sol: a cross-national comparison.

"This paper studies northern European retired immigrants, using data generated by a questionnaire survey of 300 respondents and in-depth interviews with 20 people in 13 municipalities. Reasons for moving to Spain, the advantages and disadvantages reported of living there, and the perceived impacts on the local region were analysed, paying particular attention to cross-national differences between British, German, Benelux and Nordic retirees. The results show that sociodemographic and economic features of the settlers tend to be quite similar, whilst reasons for moving, stated advantages and disadvantages, and consequences and impacts exhibit some cross-national differentiation."

Adult↗
PubMed1998

Use of scavenger beads to remove excess labeling reagents from capillary zone electrophoresis samples.

In many cases, samples for capillary zone electrophoresis (CZE) are derivatized with a chromophore or fluorophore to enhance their detectability. To ensure efficient labeling, a large excess of labeling agent is often used, which leads to the presence of a large peak for unreacted reagent. Here we report that excess reagent can be reacted with "scavenger beads" carrying an appropriate functional group to remove it from the sample solution. We present examples of removal of aminonaphthalene mono-, di-, and trisulfonic acid from mixtures in which they were used to label mono- or oligosaccharides by reductive amination. Aldehyde-containing scavenger beads were made by oxidizing Sephadex G-50 beads with sodium periodate. These were added to the labeling reaction mixtures after the reductive amination of the sugars was complete. Almost complete elimination of the peak from the labeling agent could be achieved.

Aldehydes↗