Biomedical subjects

E Velasco

Publications and source records attributed to E Velasco.

At least 19 recordsLinked to original sources

PubMed2003

Prospective evaluation of the epidemiology, microbiology, and outcome of bloodstream infections in hematologic patients in a single cancer center.

Bloodstream infections (BSIs) have an important impact on the outcome of cancer patients. A prospective cohort study was undertaken at a referral cancer center in order to describe the clinical and microbiological characteristics of patients with hematologic malignancies and BSIs and to identify independent predictors associated with mortality. The study enrolled 110 consecutive BSI episodes during an 18-month period. Patients were monitored for 30 days after the last positive blood culture. There were 10.24 BSI episodes per 1,000 patient-days. The median age of the patients was 25 years. Most patients had acute leukemia ( n=72). The origin of the BSI was unknown in 43.6% of the episodes and was associated with known sites in 32.7%. There were 58 concomitant infectious sites (lungs, 43%, and soft tissue, 22.4%) and 195 noninfectious comorbid factors (poor performance status, 30.2%; undernourishment, 14.3%). The median neutrophil count was 215 cells/mm(3). Indwelling catheters were present in 70% of the episodes. The majority of isolates obtained within the first 48 h of the BSI episode (61%) were gram-negative rods. Overall mortality was 24.5%. Multivariate analysis using logistic regression showed relapsed leukemia, poor performance status, recent weight loss, and ventilatory failure requiring ventilatory support as independent predictors of mortality. Hematologic cancer patients with BSIs should be regarded as a distinct group of patients at high risk of death. The knowledge of variables amenable to intervention would help diminish or prevent serious medical complications.

Bacteremia↗

PubMed2002

Density-functional study of the nematic-isotropic interface of hard spherocylinders.

The Somoza-Tarazona density-functional theory is applied to the isotropic-nematic interface of hard spherocylinders with length (L)-to-diameter (D) ratios in the range L/D=5-20. Properties such as the density and orientational order-parameter profiles and the variation of interfacial tension with bulk nematic tilt angle agree qualitatively with results of previous studies at larger values of L/D using both computer simulation and the Onsager second-virial approximation. The minimum interfacial tension is obtained at a tilt angle of 90 degrees. For values of L/D approximately 5, it is found that the Onsager approximation predicts a spurious minimum in the interfacial tension at small tilt angles.

Journal Article↗

PubMed2001

Self-consistent nonperturbative theory for classical systems.

We construct a self-consistent nonperturbative theory for the structure and thermodynamics of a classical system of particles that goes beyond the usual approaches based on perturbation theory. Our theory, which gives accurate predictions for the phase diagram, is based on two ingredients: first, use is made of an exact expression for the free energy of a many-body system in terms of a reference system and a coupling integral connecting the latter to the final system; second, correlation functions may be very accurately approximated using a number of sum rules relating the radial distribution function with thermodynamic quantities. Consistency between the coupling integral expression and the sum rules may be achieved by means of a self-consistent process.

Journal Article↗

PubMed2001

Layering at free liquid surfaces.

We show that simple liquids, with appropriate choices of the isotropic pair interaction, may exhibit surface layering above the melting temperature. Results for the liquid surface have been obtained by Monte Carlo simulations in slab geometry. Surface layering appears at temperatures below approximately one-third of the critical temperature for very different choices of pair interaction. The high melting temperature of the Lennard-Jones crystal preempts the observation of the oscillatory density at the free liquid interface, while model pair interaction potentials, built to reproduce some properties of mercury and the alkali metals, have low melting temperature, uncovering the region of surface layering.

Journal Article↗

PubMed2000

Epidemiology of bloodstream infections at a cancer center.

CONTEXT: Cancer patients are at unusually high risk for developing bloodstream infections (BSI), which are a major cause of in-hospital morbidity and mortality. OBJECTIVE: To describe the epidemiological characteristics and the etiology of BSI in cancer patients. DESIGN: Descriptive study. SETTING: Terciary Oncology Care Center. PARTICIPANTS: During a 24-month period all hospitalized patients with clinically significant BSI were evaluated in relation to several clinical and demographic factors. RESULTS: The study enrolled 435 episodes of BSI (349 patients). The majority of the episodes occurred among non-neutropenic patients (58.6%) and in those younger than 40 years (58.2%). There was a higher occurrence of unimicrobial infections (74.9%), nosocomial episodes (68.3%) and of those of undetermined origin (52.8%). Central venous catheters (CVC) were present in 63.2% of the episodes. Overall, the commonest isolates from blood in patients with hematology diseases and solid tumors were staphylococci (32% and 34.7%, respectively). There were 70 episodes of fungemia with a predominance of Candida albicans organisms (50.6%). Fungi were identified in 52.5% of persistent BSI and in 91.4% of patients with CVC. Gram-negative bacilli prompted the CVC removal in 45.5% of the episodes. Oxacillin resistance was detected in 26.3% of Staphylococcus aureus isolates and in 61.8% of coagulase-negative Staphylococcus. Vancomycin-resistant enterococci were not observed. Initial empirical antimicrobial therapy was considered appropriate in 60.5% of the cases. CONCLUSION: The identification of the microbiology profile of BSI and the recognition of possible risk factors in high-risk cancer patients may help in planning and conducting more effective infection control and preventive measures, and may also allow further analytical studies for reducing severe infectious complications in such groups of patients.

Adolescent↗

PubMed2000

Complex phase behavior induced by repulsive interactions

For a solid in which the interactions have a hard core plus a simple soft repulsive tail we show, using a perturbation theory, that the possible stable crystalline structures give rise to a rich phase behavior. We find two concomitant critical points each corresponding to phase transitions separating bcc and fcc structures, respectively, and the occurrence of a transition between fcc and bcc phases without change in density. This novel phenomenology may be relevant to the behavior of some metallic systems, colloids, and to water.

Journal Article↗

PubMed2000

Myoneurin, a novel member of the BTB/POZ-zinc finger family highly expressed in human muscle.

Initially characterized as Drosophila developmental regulators, the BTB/POZ and zinc finger proteins (BTB/POZ-ZF) constitute a growing family of proteins with gene expression regulatory functions since they have been shown to be involved in both transcriptional activation and repression of various genes in a broad range of species, including mammals. Here we report the cloning of a novel human transcript, coding for a 68-kDa deduced BTB/POZ-ZF protein. This molecule, called myoneurin on the basis of its prevalent expression in the neuromuscular system, contains an amino-terminal BTB/POZ domain and eight tandemly repeated zinc-finger motifs of the C(2)H(2) type. The murine myoneurin, identified in the mouse embryo, is highly homologous to the human protein.

Aging↗

PubMed2000

Density-functional theory of inhomogeneous systems of hard spherocylinders

The smectic-A phase boundaries of a hard-spherocylinder fluid are calculated using a density-functional theory based on one proposed earlier by Somoza and Tarazona [Phys. Rev. A 41, 965 (1990)]. Our calculations do not employ the translation-rotation decoupling approximation used in previous density-functional theories. The calculated phase boundaries agree well with computer simulation results up to aspect ratios L/D approximately 5 and are in better agreement with the simulations than are previous theories. We generalize the model fluid by including long-range interactions with quadrupolar orientational symmetry, which are taken into account by mean-field approximation. For sufficiently large strength, these interactions produce a smectic-C phase, which undergoes either a continuous or weakly first-order transition to the smectic-A phase. The theory and numerical methods discussed here can be applied to the analysis of interfacial phenomena.

Journal Article↗

PubMed1999

HIV-associated pityriasis rubra pilaris responsive to triple antiretroviral therapy.

HIV-associated pityriasis rubra pilaris (PRP) or PRP type VI designates a new distinctive entity reported in HIV patients. It is characterized by cutaneous lesions of PRP and variable association with lesions of acne conglobata, hidradenitis suppurativa and lichen spinulosus. We report a patient with HIV-associated PRP which was treated by triple antiretroviral therapy (zidovudine, lamivudin and saquinavir) with complete response. The patient has remained free from symptoms for 20 months of follow-up. We review the clinical features, pathology, evolution, treatment and possible aetiology of this recently described entity.

Acquired Immunodeficiency Syndrome↗

PubMed1999

Basal cell carcinoma of the scrotum.

An 80-year-old man with a 7 year history of a slowly enlarging, asymptomatic scrotal nodule is presented. He had a negative history for sexually transmitted disease, trauma to the area, radiotherapy and chemical or arsenic exposure. The lesion was excised with a margin of 0.8 cm of normal skin. Examination of the specimen revealed a basal cell carcinoma.

Aged↗

PubMed1999

Phase behavior of binary hard-sphere mixtures from perturbation theory.

Using a first-order perturbation theory, we have studied the phase diagram of a binary mixture of hard spheres for different values of the size ratio. Recent models for the two-body depletion potential between large spheres are used to take into account the role of the small spheres. The theory predicts a complex phase diagram including a fluid-solid transition at high packing fraction of small spheres, metastability of fluid-fluid demixing, an isostructural solid-solid transition at high packing fraction of the large spheres for sufficiently small values of the size ratio q of the spheres, and the tendency to sticky-sphere behavior in the limit q-->0. The agreement with recent simulation results is quite good. We also show that this phenomenology was already implicit in the pioneering work of Asakura and Oosawa.

Journal Article↗

PubMed1999

Comparison of the toxicity of amphotericin B in 5% dextrose with that of amphotericin B in fat emulsion in a randomized trial with cancer patients.

A multicentric randomized trial was undertaken to compare the toxicity of amphotericin B in 5% dextrose with that of amphotericin B in a fat emulsion (Intralipid) in cancer patients. Group 1 (n = 33) received amphotericin B diluted in 5% dextrose with premedication consisting of promethazine plus an antipyretic. Group 2 (n = 28) received amphotericin B diluted in 20% Intralipid without premedication. Amphotericin B was infused daily at a dose of 1 mg/kg of body weight over a 1-h period to members of both groups for empirical antifungal therapy (in neutropenic patients) or for the treatment of documented fungal infections. The majority of patients (80%) received empirical amphotericin B treatment. The two groups were comparable with regard to age, gender, underlying disease, and the following baseline characteristics: use of other nephrotoxic drugs and serum levels of potassium and creatinine. The median cumulative doses of amphotericin B were 240 mg in group 1 and 245 mg in group 2 (P = 0.73). Acute adverse events occurred in 88% of patients in group 1 and in 71% of those in group 2 (P = 0.11). Forty percent of the infusions in group 1 were associated with fever, compared to 23% in group 2 (P < 0.0001). In addition, patients in group 2 required less meperidine for the control of acute adverse events (P = 0.008), and fewer members of this group presented with hypokalemia (P = 0.004) or rigors (P < 0.0001). There was no difference in the proportions of patients with nephrotoxicity (P = 0.44). The success rates of empirical antifungal treatment were similar in the two groups (P = 0.9). Amphotericin B diluted in a lipid emulsion seems to be associated with a smaller number of acute adverse events and fewer cases of hypokalemia than amphotericin B diluted in 5% dextrose.

Adolescent↗

PubMed1998

Risk factors for bloodstream infections at a cancer center.

A hospital-based matched case-control study was conducted in order to identify risk factors for the development of bloodstream infections in adult hospitalized patients. Between January 1993 and December 1994, 264 episodes of bloodstream infection were evaluated. Significant variables identified by univariate analysis were included in a multivariate model that showed that central venous catheter [odds ratio (OR), 6.71], poor performance status (OR, 3.40), weight loss (OR, 2.47), hematologic diseases (OR, 2.24), and previous antimicrobial therapy (OR, 2.12) independently influenced the outcome. The knowledge of modifiable risk factors is useful in the development of strategies that may contribute to the prevention of bloodstream infections.

Adolescent↗

PubMed1998

Risk index for prediction of surgical site infection after oncology operations.

INTRODUCTION: Several studies have shown that surgical site infections represent most hospital-acquired infections, with the major impact being on average hospital stay and cost of hospitalization. METHODS: To develop a risk model for prediction of surgical site infections in cancer patients undergoing operative procedures and identify those with high probability of infection we performed a prospective cohort study in a tertiary cancer care hospital in Rio de Janeiro, Brazil. Risk factors were studied in single and multivariate analyses. RESULTS: Over a 24-month period, 1205 patients underwent operations for malignant disease. The overall surgical site infection rate was 17.3%. A multivariate stepwise logistic regression model identified six independent predictive risk factors: contaminated and infected operations, surgical duration greater than 280 minutes, male sex, prior radiotherapy, American Society of Anesthesiology class III to V, and antimicrobial prophylaxis not according to protocol. On the basis of individual risk scores, two groups of patients were identified: a low-risk (score < or = 8; surgical site infection rate 10%) and a high-risk group (score > or = 9; surgical site infection rate 33.6%; relative risk 3.4; 95% confidence interval 2.6 to 4.4). CONCLUSION: The oncology risk model allowed for the identification of a high-risk score group of patients and implementation of a more efficient and selective intervention program.

Brazil↗

PubMed1998

Fungemia in cancer patients in Brazil: predominance of non-albicans species.

The objective of this study was to characterize the epidemiology of candidemia in cancer patients in the city of Rio de Janeiro, Brazil. An 18-month survey of fungemia in patients with cancer was undertaken in three Hospitals in Rio de Janeiro. Forty-three episodes of candidemia were identified in 43 patients, 43 of which were episodes of candidemia; in ten case the strains were not available for further identification of species and were excluded from this analysis. The overall distribution of fungi causing fungemia was: Candida albicans (5), Candida tropicalis (16), Candida parapsilosis (6), Candida guilliermondii (4), Candida lusitaniae (1) and Candida stellatoidea (1). Antifungal prophylaxis had been administered before the episode of fungemia in only six patients (18.2%): oral itraconazole in three patients and oral nistatin, low dose intravenous amphotericin B and oral fluconazole in one patient each. There was no difference in the presence of risk factors, clinical characteristics or in the outcome between albicans and non-albicans species, nor between Candida tropicalis and other non-albicans species. There was a clear predominance of non-albicans species, regardless of the underlying disease, antifungal prophylaxis or the presence of neutropenia.

Brazil↗

PubMed1998

Risk factors for death among cancer patients with fungemia.

In order to identify prognostic factors for death among cancer patients with fungemia, an 18-month survey of fungemia in patients with cancer was undertaken in three hospitals in Rio de Janeiro. For the assessment of risk factors for death, the following variables were analyzed: age; gender; underlying cancer; last treatment for the underlying disease; previous surgery; use of antibiotics, antifungal agents, steroids, or total parenteral nutrition; use of a central venous catheter; chemotherapy; radiotherapy; presence and duration of neutropenia; etiologic agent of the fungemia; treatment of the fungemia; clinical manifestations; and performance status (Karnofsky score) on the day of the positive blood culture. In multivariate analysis, the variables associated with an increased risk for death were older age, persistent neutropenia, and low performance status. Identifying risk factors for death may help to define a group-risk patients for whom new therapeutic options should be tried.

Adult↗

PubMed1998

An outbreak of Bacillus species in a cancer hospital.

Bacillus species were recovered from the blood cultures of 39 oncology patients over 14 weeks. A matched case-control study showed a strong association of Bacillus species bacteremia with use of calcium gluconate solution (odds ratio=25.0) and of central venous lines (odds ratio=8.8). Stopping use of the implicated calcium gluconate vials controlled the outbreak.

Adolescent↗

PubMed1998

Analysis of the monomeric alphoid sequences in the pericentromeric region of human chromosome 7.

To further define the structure of the pericentromeric region of human chromosome 7, we have identified and characterized a YAC clone (YAC 311.H5) containing the D7S1480 locus, which maps to the short arm near the centromere of this chromosome, by linkage in CEPH families and radiation hybrid analysis. This YAC contains two new blocks of alphoid DNA (named Z5 and Z6). Both Z5 and Z6 show monomeric structures and a lack of higher-order repeats, and, therefore, belong to suprachromosomal family type 4 (M1). The orientation of the two blocks and the physical distances over the region were defined by pulsed-field gel electrophoresis (PFGE) and fluorescence in situ hybridization on chromatin fibers (FiberFISH). A YAC contig spanning the centromeric region has been developed by STS content.

Cells, Cultured↗