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Biomedical subjects

C Prieto

Publications and source records attributed to C Prieto.

At least 19 recordsLinked to original sources
PubMed2006

Six years experience in intracoronary brachytherapy procedures: patient doses from fluoroscopy.

Typical patient dose levels during intracoronary brachytherapy (ICB) procedures using beta sources were determined across a sample of 221 treatments. Dose-area product values, fluoroscopy time and number of frames per procedure, with median values of 62 Gy cm2, 17.0 min and 1493 images, respectively, resulted in a 20% to 50% increase in the values measured for percutaneous transluminal coronary angioplasty procedures in the same medical centre (median values 41 Gy cm2, 14.3 min and 1078 images). Likely reasons for this increase include the additional complexity of ICB, the need for recording and reporting every step of the treatment, getting the essential parameters for the volume determination of the lesion and therapeutic radiation dose calculation and, finally, the learning curve for this kind of procedure. A high concentration skin dose distribution during ICB procedures was measured and in 12% of the patients peak skin doses higher than 1.5 Gy were confirmed. 10 patients were submitted to clinical follow-up and skin injuries were not identified.

Angioplasty, Balloon, Coronary↗
PubMed2006

A comparison of enhanced green fluorescent protein expression induced by immediate-early cytomegalovirus (IE-CMV) and gG pseudorabies virus (gG-PRV) promoters, using pseudorabies virus amplicons as vectors.

This study compares the expression efficiencies of the IE-CMV and gG-PRV promoters following their transfection into cultured human and monkey cells, using pseudorabies virus amplicons as vectors and enhanced green fluorescence protein (EGFP) as an expression marker. EGFP expression was similarly strong with both promoters. Pseudorabies virus amplicons appear to be useful vectors in gene expression studies due to their replication in the presence of helpers and their wide range of cellular hosts.

Animals↗
PubMed2006

Algorithm to find gene expression profiles of deregulation and identify families of disease-altered genes.

MOTIVATION: Alteration of gene expression often results in up- or down-regulated genes and the most common analysis strategies look for such differentially expressed genes. However, molecular disease mechanisms typically constitute abnormalities in the regulation of genes producing strong alterations in the expression levels. The search for such deregulation states in the genomic expression profiles will help to identify disease-altered genes better. RESULTS: We have developed an algorithm that searches for the genes which present a significant alteration in the variability of their expression profiles, by comparing an altered state with a control state. The algorithm provides groups of genes and assigns a statistical measure of significance to each group of genes selected. The method also includes a prefilter tool to select genes with a threshold of differential expression that can be set by the user ad casum. The method is evaluated using an experimental set of microarrays of human control and cancer samples from patients with acute promyelocytic leukemia.

Algorithms↗
PubMed2006

The application of image quality measurements for digital angiography.

The image quality (IQ) evaluation of a charge-coupled device (CCD)-based digital angiography system was assessed with respect to modulation transfer function and noise power spectrum. These values were used to calculate the system's frequency-dependent detective quantum efficiency (DQE). The X-ray image detector was an image intensifier (II) lens coupled to a CCD camera. Two measurement setups were used. Setup A is standard IQ assessment, while Setup B more closely represented clinical conditions (polymethyl methacrylate (PMMA) of varying thickness placed between the X-ray tube and II, with test object positioned between PMMA slices 30 cm from the II). Exposure parameters varied according to automatic brightness control settings. Setup B included X-ray radiation scattered by the patient-PMMA. A clinical DQE, describing the transmission of the input signal-to-noise ratio associated with both primary and secondary X-ray spectra, was defined.

Angiography↗
PubMed2006

Evaluation of risk of deterministic effects in fluoroscopically guided procedures.

A methodology for the evaluation of skin dose distribution and possible skin injuries on patients undergoing interventional procedures has been developed as part of the European DIMOND programme. Relevant dosimetric data from the procedures are recorded and other specific measurements for skin dose evaluation (slow films for therapy, radiochromic films, thermoluminescence dosemeters and optically stimulated luminescence dosemeters) have been carried out. For non-cardiac and for some cardiac procedures, dose-area product values of 200 and 300 Gy cm2 were proposed, respectively, as a trigger level for further detailed skin dose investigation and possible clinical follow-up. Results from a survey of 191 selected complex procedures are reported. Out of all the patients included in the trial, 16% received skin doses > or =1.5 Gy. No skin injuries were found in any of the patients followed.

Dose-Response Relationship, Radiation↗
PubMed2006

Patient dosimetry and image quality in digital radiology from online audit of the X-ray system.

The present work describes an online patient dosimetry and an image quality system in digital radiology. For the patient dosimetry audit, current mean values of entrance surface dose (ESD) were compared with local and national reference values (RVs) for the specific examination type evaluated. Mean values exceeding the RV trigger an alarm signal and then an evaluation of the technical parameters, operational practice and image quality was begun, using data available in the DICOM header to derive any abnormal settings or performance to obtain the image. The X-ray tube output for different kVp values is measured periodically, to allow for the automatic calculation of ESD. The system allows also for image audit, linking the dose imparted, the image quality and the alarm condition, if produced. Results and the benefits derived from this online quality control are discussed here.

Humans↗
PubMed2006

Influence of patient thickness and operation modes on occupational and patient radiation doses in interventional cardiology.

Patient and staff dose values in an interventional cardiology laboratory for different operational modes and several patient thicknesses (from 16 to 28 cm, simulated using polymethylmethacrylate) are presented. When increasing patient thicknesses and depending on fluoroscopy and cine modes, occupational doses can increase >30 times the baseline level. Scatter dose rates at the cardiologist's position with no radiation protective tools ranged from 1 to 14 mSv h(-1) for fluoroscopy, and from 10 to 47 mSv h(-1) during cine acquisition. Patient entrance surface air kerma rates increased by nearly 3 and staff dose rates by up to 2.6 when fluoroscopy was moved from the low to the high mode, for a typical 20 cm thickness. The respective increase factors were 6 and 4.2 when patient thickness rose from 16 to 28 cm, and by 10 and 8.3, when comparing cine acquisition with the low fluoroscopy mode. The knowledge of typical dose rates for each X-ray system in use in catheterisation laboratories is essential in order to optimise protection of patients and staff.

Body Constitution↗
PubMed2006

[Utility of bolus somatostatin administration in preventing pancreatitis after endoscopic retrograde cholangiopancreatography: a controlled, non-randomized study].

INTRODUCTION: Somatostatin is one of the most extensively evaluated drugs in the prophylaxis of pancreatitis after endoscopic retrograde cholangiopancreatography (ERCP), but its utility remains controversial. PATIENTS AND METHODS: The aim of this study was to evaluate the role of somatostatin as prophylaxis of ERCP-induced acute pancreatitis. A group of consecutive patients that underwent ERCP in our endoscopy unit was prospectively studied for 8 months. Patients in this group were administered an endovenous bolus of 250 micrograms of somatostatin immediately before introducing the catheter in the papilla of Vater (somatostatin group). This group was compared with another group composed of consecutive patients who had undergone ERCP in the 8 previous months, without somatostatin administration (placebo group). Both groups contained the same number of patients. The following variables were recorded; sex, age, contrast injection in the duct of Wirsung, endoscopist, therapeutic maneuvers, and the development of post-ERCP pancreatitis. RESULTS: During the 16 months of patient inclusion, we performed 320 ERCP in our unit, of which 248 were included in the study: 142 in the somatostatin group and 142 in the placebo group. Of these patients, 152 (53.5%) were men and 132 (46.5%) were women. The mean age was 70.05 +/- 13.83 years (range: 27-93 years). Acute pancreatitis occurred in 10 patients in the somatostatin group and in 5 in the placebo group; this difference was not statistically significant (p > 0.05). No significant differences were found between the two groups in the remaining variables studied. CONCLUSION: Somatostatin does not seem to be useful in preventing post-ERCP acute pancreatitis.

Aged↗
PubMed2006

Informed consent document in gastrointestinal endoscopy: understanding and acceptance by patients.

OBJECTIVE: We wanted to know if patients read and understand the informed consent (IC) document used for endoscopic procedures, and to evaluate the readability of IC. METHOD: During two months we gave patients studied in our endoscopy unit an anonymous questionnaire with different items concerning reading degree, knowledge of the technique, complications, sedation used, and information received. We evaluated IC readability using the Flesch index. RESULTS: 309 patients were included (mean age: 53 years, 55% males, 86% outpatients, 50% with basic education); 85% of patients read the IC, 96% considered they understood the exploration technique, 22% were not aware of severe complications, and 82% knew which kind of sedation would be used; 88% of patients received additional information from their doctors. Outpatients read the IC in a greater percentage versus inpatients (p < 0.05); patients with only basic education tended to ignore the possibility of complications (p < 0.05). Doctors gave more information to rural patients (p = 0.08), offered better information about complications to urban patients (p = 0.09), and offered more information on other diagnostic procedures to patients older than 50 years (p < 0.05). With the Flesch index we found that gastroscopy and colonoscopy ICs had a "standard" level of readability, while ERCP ICs were more complex. CONCLUSIONS: The majority of our patients read and understands the IC. Doctors adapt information to patient characteristics. Our IC documents have an acceptable level of readability, but given that 50% of our patients have only a basic educational status, we should attempt to provide an easier IC document.

Adolescent↗
PubMed2005

Characterization of Bordetella pertussis growing as biofilm by chemical analysis and FT-IR spectroscopy.

Although Bordetella pertussis, the etiologic agent of whooping cough, adheres and grows on the ciliated epithelium of the respiratory tract, it has been extensively studied only in liquid cultures. In this work, the phenotypic expression of B. pertussis in biofilm growth is described as a first approximation of events that may occur in the colonization of the host. The biofilm developed on polypropylene beads was monitored by chemical methods and Fourier transform infrared (FT-IR) spectroscopy. Analysis of cell envelopes revealed minimal differences in outer membrane protein (OMP) pattern and no variation of lipopolysaccharide (LPS) expression in biofilm compared with planktonically grown cells. Sessile cells exhibited a 2.4- to 3.0-fold higher carbohydrate/protein ratio compared with different types of planktonic cells. A 1.8-fold increased polysaccharide content with significantly increased hydrophilic characteristics was observed. FT-IR spectra of the biofilm cells showed higher intensity in the absorption bands assigned to polysaccharides (1,200-900 cm(-1) region) and vibrational modes of carboxylate groups (1,627, 1,405, and 1,373 cm(-1)) compared with the spectra of planktonic cells. In the biofilm matrix, uronic-acid-containing polysaccharides, proteins, and LPS were detected. The production of extracellular carbohydrates during biofilm growth was not associated with changes in the specific growth rate, growth phase, or oxygen limitation. It could represent an additional virulence factor that may help B. pertussis to evade host defenses.

Bacterial Adhesion↗
PubMed2005

Comparison of cytomegalovirus viral load measure by real-time PCR with pp65 antigenemia for the diagnosis of cytomegalovirus disease in solid organ transplant patients.

Cytomegalovirus (CMV) infection is the most frequent complication in solid organ transplant recipients. Currently, the antigenemia assay is widely used to detect this infection, although its success is being questioned to a great extent nowadays. The aim of our study is to compare a quantitative real time PCR to measure CMV DNA to the antigenemia assay, for the diagnosis to CMV disease. For our research, we prospectively processed 1198 samples (plasma and peripheral blood leukocytes [PBMC]), which belonged to 158 transplant recipients. In every sample the detection of the pp65 antigen in PBMC was carried out, as well as the quantification of CMV DNA by PCR (Light Cycler, LC-PCR). For this process, FRET probes, which detect a 254-bp fragment from the CMV gB gene, were used. The dynamic range of the LC-PCR was 500 to 5.10(7) copies/mL plasma and from 62 to 6.10(6) copies/10(6) PBMC. Twenty-three episodes of cytomegalovirus (CMV) disease occurred in 22 out of 158 patients and PCR displayed levels of sensitivity and specificity of 100% and 67%, respectively. The antigenemia assay obtained values of 91% and 57%. We established a cutoff value of 10(3) copies/mL plasma and 315 copies/10(6) cells. According to these cutoff values, PCR showed levels of sensitivity, specificity, VPN and VPP of 95.6%, 81.6%, 99%, and 53% respectively. Moreover, the LC-PCR assay anticipated the antigenemia assay in 10 patients out of 22 who developed CMV disease and the appearance of any clinical symptoms in 12 out of 22 patients. In conclusion, we believe that the quantification of CMV DNA by LC-PCR is a superior assay to pp65 antigenemia test regarding the early diagnosis of CMV disease in solid organ transplant recipients.

Cytomegalovirus↗
PubMed2005

[General malaise and diarrhea as the main manifestations of Giardia lamblia infection].

Giardia lamblia is a ubiquitous intestinal protozoan. Transmission, which is fecal-oral, occurs after cyst ingestion, excystation and enterocyte adhesion. Symptoms include diarrhea, abdominal pain and other less frequent manifestations such as nausea, anorexia and weight loss. Enzyme immunoassay and direct fluorescent-antibody assay for antigen detection in stool samples, and small intestine biopsy provide the best diagnostic sensitivity. When an infection is suspected, duodenal biopsy should be carried out, even though endoscopic appearance may be normal. The most effective drugs in the treatment of this infection are metronidazole and tinidazole. We report a case of G. lamblia infection. The patient reported a clinical history of 4 months' duration with general malaise and diarrhea for the previous month. This form of presentation is rarely found in adults with this parasitosis. The diagnosis was based on the results of duodenal biopsy. The patient showed satisfactory response to treatment with metronidazole.

Animals↗
PubMed2003

Patterns of exposure to Lawsonia intracellularis infection on European pig farms.

A serological investigation was made of the patterns of exposure of pigs to Lawsonia intracellularis, the causative agent of proliferative enteropathy (ileitis), on farms in France and Spain. Blood samples from groups of adult female pigs in breeding programmes and from postweaning pigs were monitored, the latter every month for five months, by a L. intracellularis-specific immunofluorescence seroassay. Four of 33 farms monitored in France (12 per cent) and three of 29 farms monitored in Spain (10.3 per cent) remained free of clinical signs and seronegative throughout the study. The postweaning pigs on all of the remaining French farms and on 20 of the 26 remaining Spanish farms had a pattern of infection characterised by seroconversion in the grower period, generally between eight and 16 weeks of age. The seroprevalence in these groups ranged from 8 to 20 per cent. On all of these farms at least 15 per cent of the breeding females tested were seropositive, and the farms were under similar management systems, with a continuous flow of pigs or between buildings on one site, so-called 'one site, farrow-to-finish'. On the six remaining Spanish farms, under two management groups, a multiple-site system was used, with the piglets being separated from the adults at weaning and moved to a separate location. On three of these farms, the pattern of infection was characterised by seroconversion later in the finisher period, at between 16 and 20 weeks of age, and none of the breeding females was seropositive. On the three other multiple-site farms the pattern of infection resembled that on the one-site farms. On all of the farms, the seroconversion of groups of pigs was frequently associated with clinical or subclinical signs of ileitis.

Animals↗
PubMed2003

Skin dose and dose-area product values in patients undergoing intracoronary brachytherapy.

Entrance skin doses, dose-area product (DAP) values, fluoroscopy times and digital cine acquisition data were measured for 86 patients undergoing intracoronary brachytherapy procedures with beta sources, to estimate risk of skin injuries. Interventions were carried out in three dedicated X-ray interventional cardiology rooms equipped with X-ray systems operating in pulsed modes, with high filtration and edge filter options. Skin dose distribution was analysed in detail in 56 patients using slow films and thermoluminescent dosimetry. Digital recording of Digital Imaging and Communications in Medicine cine images also allowed analysis of the technical parameters used throughout the procedures. A protocol for clinical follow-up of these patients at the cardiology service is also presented, which prescribes special attention when a threshold dose is reached. Median values for DAP, fluoroscopy time and number of frames were 81.2 Gy cm(2), 17.5 min and 1569 frames, respectively, and maximum values were 323.3 Gy cm(2), 46.2 min and 3213 frames, respectively. In two cases, maximum skin doses in a procedure reached 3.5 Gy and 4.6 Gy. Comparing median values in this study, intracoronary brachytherapy involved approximately two-fold the DAP used in percutaneous transluminal coronary angioplasty procedures performed during the same period in the same catheterization laboratories, as a consequence of the need to monitor the radioactive source location used for the treatment of stenoses and the intravascular ultrasound. Special care must be paid in those cases of high dose in relation to potential patient skin injuries and late effects.

Brachytherapy↗
PubMed2003

Short communication: Practical aspects for the evaluation of skin doses in interventional cardiology using a new slow film.

Mapping skin doses in complex fluoroscopy interventions is useful to determine the probability of a possible injury, to detect areas of overlapping irradiation fields and to obtain a permanent register of the most exposed patient skin areas. To fulfil this task, large films with slow X-ray response can be used. Recently, Kodak has introduced a new radiotherapy verification film, named EDR2 (Extended Dose Range). The aim of this paper is to analyse the possibilities of using this new film for estimating skin dose distributions in interventions with potentially higher doses, such as complex percutaneous transluminal coronary angioplasty (PTCA), intravascular brachytherapy procedures (IVB) or cardiac ablations. The EDR2 film by Kodak is an improved option to be used in interventional cardiology to obtain maps of patient skin doses and to estimate maximum skin doses up to 1400 mGy. Film kVp dependence is negligible and the processor conditions can be standardized to obtain skin dose estimations. The linear range for accurate dose measurements is from 50 mGy to 500 mGy.

Angioplasty, Balloon, Coronary↗
PubMed2001

A-549 is a suitable cell line for primary isolation of coxsackie B viruses.

A common receptor for coxsackie B virus and adenovirus has been described recently in cells of human and murine origin. Since the established cell line A-549 is suitable for adenoviruses, the potential use of A-549 cells for the isolation of coxsackie B viruses from clinical samples was investigated. All throat swabs sent to the laboratory between April 1998 and June 1999 were inoculated onto monolayers of MRC-5 and A-549 cells in tubes, and the enterovirus isolates obtained were typed. From April to June 1999, A-549 cells were compared prospectively to Buffalo green monkey (BGM) cells, considered as the most susceptible cell line for isolating coxsackie B viruses. Fifty-six out of 171 enterovirus isolates (33%) displayed a cytopathic effect (CPE) in the A-549 monolayer only, 48 isolates (28%) in the MRC-5 monolayer only, and 67 isolates (39%) in both cell lines. Most isolates that showed CPE in A-549 cells only (48 out of 56, 86%) were coxsackie B viruses, belonging to four different serotypes (B1, B2, B4, and B6). When BGM and A-549 cells were inoculated in parallel, both recovered the same number of coxsackie B isolates (n = 20), and the CPE was noted on approximately the same day. In conclusion, growth in A-549 but not MRC-5 cells identified coxsackie B viruses in most cases. A-549 was comparable to BGM for primary isolation of coxsackie B viruses.

Cell Line↗