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Biomedical subjects

A Alvarez

Publications and source records attributed to A Alvarez.

At least 19 recordsLinked to original sources
PubMed2006

Presentation and role of transplantation in adult patients with type 1 primary hyperoxaluria and the I244T AGXT mutation: Single-center experience.

Primary hyperoxaluria type 1 (PH1) is a rare genetic disorder characterized by allelic and clinical heterogeneity. We aim to describe the presentation and full single-center experience of the management of PH1 patients bearing the mutation described in our community (I244T mutation+polymorphism P11L). Since 1983, 12 patients with recurrent renal lithiasis have been diagnosed with PH1 and renal failure in the Canary Islands, Spain. Diagnostic confirmation was based on the presence of oxalosis in undecalcified bone or kidney allograft biopsy, reduced alanine:glyoxylate aminotransferase activity in liver biopsy, and blood DNA analysis. Patients underwent different treatment modalities depending on individual clinical circumstances and therapeutic possibilities at the time of diagnosis: hemodialysis, isolated kidney, simultaneous liver-kidney, or pre-emptive liver transplantation. In all cases, the presentation of advanced renal disease was relatively late (>13 years) and no cases were reported during lactancy or childhood. The eight patients treated with hemodialysis or isolated kidney transplantation showed unfavorable evolution leading to death over a variable period of time. In contrast, the four patients undergoing liver transplantation (three liver+kidney and one pre-emptive liver alone) showed favorable long-term allograft and patient survival (up to 12 years follow-up). In conclusion, in this PH1 population, all bearing the I244T mutation, the development of end-stage renal disease was distinctive during late adolescence or adulthood. Our long-term results support pre-emptive liver transplantation at early stages of renal failure, and kidney-liver transplantation for those with advanced renal disease.

Adolescent↗
PubMed2006

Improved human islet isolation using nicotinamide.

We investigated the effects of nicotinamide (NA) supplementation of the processing medium during islet isolation. One hundred and two human pancreata were processed for clinical transplantation after preservation either in the University of Wisconsin (UW) or using the two-layer method (TLM). Pancreata were then divided into four groups and retrospectively analyzed. Group I: UW preservation followed by processing without NA, Group II: UW preservation and processing with NA, Group III: TLM preservation without NA, Group IV: TLM preservation with NA. We observed a significant increase in islet yield in Group II (4343+/-348 IEQ/g) [mean+/-SEM], compared to Group I (2789+/-348 IEQ/g) (p=0.005). Similarly, a significant increase in islet yield was observed when NA was used in the processing of organs preserved with TLM (Group IV: 5538+/-413 vs. Group III: 3500+/-629; p=0.02). Furthermore islet yield was higher in Group IV than in Group II (p<0.05). The percentages of preparations that qualified for transplantation were 25, 47, 45, 69% in Groups I, II, III, IV, respectively. Addition of NA to the processing medium significantly improved islet yields in both the UW and TLM preservation protocols, allowing for a higher percentage of islet preparations to qualify for clinical transplantation.

Adenosine↗
PubMed2006

Bronchoscopic balloon dilatation in the management of bronchial stenosis following lung transplantation.

BACKGROUND: Bronchial stenosis (BS) is currently found in 7-15% of lung transplantation (LT) recipients. Current treatment strategies have included Nd:Yag laser, cryotherapy, bougie dilatation and stent placement. Bronchoscopic balloon dilatation has been used as alternative treatment in a few cases with controversial results. This is a study to prospectively assess the efficacy of bronchoscopic balloon dilatation as a first step in the management of post-LT BS. METHODS: From January 1995 to December 2002, bronchoscopic balloon dilatation was evaluated as first therapeutic option in all consecutive LT patients with BS. Symptoms, pulmonary function tests, airway diameter and use of other therapeutic techniques were evaluated. RESULTS: A total of 10 out of 284 anastomed airways (3.5%) in 9 out of 152 LT patients were included in the study and follow-up lasted from 6 to 81 months. Dilatation of all but one BS met with initial success: increase of both luminal dimensions and forced vital capacity (P=0.01), and relief of symptoms. Bronchoscopic balloon dilatation long-term follow-up showed effective results in 5 out of 10 (50%) bronchial stenoses, after an average of 4 bronchoscopic balloon dilatation procedures (range 1-8). No severe complications were observed. Stent placement was required in the other 5 bronchial stenoses. CONCLUSIONS: Bronchoscopic balloon dilatation is a safe method that should be considered as first therapeutic treatment of post-LT BS. Its use avoids the need for stent placement in up to 50% of cases.

Adult↗
PubMed2006

The effect of different propolis harvest methods on its lead contents determined by ET AAS and UV-visS.

Argentinean propolis is exported to different countries, specially Japan. The market demands propolis quality control according to international standards. The analytical determination of some metals, as lead in food, is very important for their high toxicity even in low concentrations and because of their harmful effects on health. Flavonoids, the main bioactive compounds of propolis, tend to chelate metals as lead, which becomes one of the main polluting agents of propolis. The lead found in propolis may come from the atmosphere or it may be incorporated in the harvest, extraction and processing methods. The aim of this work is to evaluate lead level on Argentinean propolis determined by electrothermal atomic absorption spectrometry (ET AAS) and UV-vis spectrophotometry (UV-visS) methods, as well as the effect of harvest methods on those contents. A randomized test with three different treatments of collection was made to evaluate the effect of harvest methods. These procedures were: separating wedges (traditional), netting plastic meshes and stamping out plastic meshes. By means of the analysis of variance technique for multiple comparisons (ANOVA) it was possible to conclude that there are significant differences between scraped and mesh methods (stamped out and mosquito netting meshes). The results obtained in the present test would allow us to conclude that mesh methods are more advisable than scraped ones in order to obtain innocuous and safe propolis with minor lead contents. A statistical comparison of lead determination by both, ET AAS and UV-visS methods, demonstrated that there is not a significant difference in the results achieved with the two analytical techniques employed.

Electrochemistry↗
PubMed2006

Evaluation of voice pathology based on the estimation of vocal fold biomechanical parameters.

Voice disorders are a source of increasing concern as normal voice quality is a social demand for at least one third of the population in developed countries in cases where voice is an essential resource in professional exercise. In addition, the growing exposure to certain pathogenic factors such as smoking, alcohol abuse, air pollution, and acoustic contamination, and other problems such as gastro-esopharyngeal reflux or allergy as well as aging, aggravate voice disorders. Voice pathologies justify the assignment of larger resources to prevention policies, early detection, and less aggressive treatments. Traditional pathology detection relies on perceptive evaluation methods (GRABS), acoustic analysis, and visual inspection (indirect laryngoscopy, and modern fibro-endo-stroboscopy). This article describes a method for voice pathology detection based on the noninvasive estimation of vocal cord biomechanical parameters derived from voice using specific signal processing methods. Preliminary results using records from patients showing four frequent causes of voice pathology (nodules, polyps, chronic laryngitis, and Reinke's edema) are given. The results show that the alteration (distortion, unbalance, or deviation) of cord biomechanical parameters may serve as an indicator of pathology. Statistical methods based on hierarchical clustering and principal component analysis reveal that combining biomechanical estimates with classic perturbation parameters increases the accuracy of acoustic analysis, improving the detection of voice pathology. This research could open new possibilities for noninvasive screening of vocal fold pathologies and could be used in the implantation of e-health voice care services.

Biomechanical Phenomena↗
PubMed2006

A photometric redshift of z = 6.39 +/- 0.12 for GRB 050904.

Gamma-ray bursts (GRBs) and their afterglows are the most brilliant transient events in the Universe. Both the bursts themselves and their afterglows have been predicted to be visible out to redshifts of z approximately 20, and therefore to be powerful probes of the early Universe. The burst GRB 000131, at z = 4.50, was hitherto the most distant such event identified. Here we report the discovery of the bright near-infrared afterglow of GRB 050904 (ref. 4). From our measurements of the near-infrared afterglow, and our failure to detect the optical afterglow, we determine the photometric redshift of the burst to be z = 6.39 - 0.12 + 0.11 (refs 5-7). Subsequently, it was measured spectroscopically to be z = 6.29 +/- 0.01, in agreement with our photometric estimate. These results demonstrate that GRBs can be used to trace the star formation, metallicity, and reionization histories of the early Universe.

Journal Article↗
PubMed2006

Effectiveness and safety of an emergency department short-stay unit as an alternative to standard inpatient hospitalisation.

BACKGROUND: Emergency department short-stay units (EDSSUs) are currently emerging worldwide as an alternative to standard inpatient hospitalisation. In our hospital, a 960-bed teaching tertiary institution in Barcelona, Spain, an EDSSU has been in operation during winter periods (November-March) since 1997. AIM: To determine the efficacy and safety of our EDSSU. METHODS: Retrospective analysis of activity and quality outcomes, assessment of patient satisfaction levels and determination of the diagnostic-related groups that were mainly responsible for admissions to the EDSSU, comparing the clinical characteristics of those patients with the characteristics of patients with similar clinical diagnoses admitted to standard hospitalisation units. RESULTS: 5666 patients were treated in the EDSSU, with a progressive increase in the number of patients admitted per period, ranging from 707 in 1997-8 to 1227 in 2003-4 (73.5% increase). The mean length of stay ranged from 3.1 to 2.8 days, mortality from 2.5% to 5.1%, home discharge rate from 84% to 90%, and hospital readmission rate within the first week after discharge from 3.9% to 6.2%. In all, 98% of patients were satisfied with their stay at the EDSSU. The main diagnostic-related groups were chronic obstructive pulmonary disease (COPD = 50%) and acute heart failure (28%). Patients with COPD admitted at the EDSSU (n = 545) showed significantly (p = 0.05) lower mean length of stay (3.4 v 12 days) and mortality (1.7% v 8.1%), but a higher hospital readmission rate (9.9% v 7%) than those admitted to standard inpatient units (n = 1961). CONCLUSIONS: In our experience, the EDSSU proved to be an effective and safe alternative to standard inpatient hospitalisation.

Aged↗
PubMed2006

Stem cell strategies for Alzheimer's disease therapy.

We have found much evidence that the brain is capable of regenerating neurons after maturation. In our previous study, human neural stem cells (HNSCs) transplanted into aged rat brains differentiated into neural cells and significantly improved the cognitive functions of the animals, indicating that HNSCs may be a promising candidate for cell-replacement therapies for neurodegenerative diseases including Alzheimer's disease (AD). However, ethical and practical issues associated with HNSCs compel us to explore alternative strategies. Here, we report novel technologies to differentiate adult human mesenchymal stem cells, a subset of stromal cells in the bone marrow, into neural cells by modifying DNA methylation or over expression of nanog, a homeobox gene expressed in embryonic stem cells. We also report peripheral administrations of a pyrimidine derivative that increases endogenous stem cell proliferation improves cognitive function of the aged animal. Although these results may promise a bright future for clinical applications used towards stem cell strategies in AD therapy, we must acknowledge the complexity of AD. We found that glial differentiation takes place in stem cells transplanted into amyloid-( precursor protein (APP) transgenic mice. We also found that over expression of APP gene or recombinant APP treatment causes glial differentiation of stem cells. Although further detailed mechanistic studies may be required, RNA interference of APP or reduction of APP levels in the brain can significantly reduced glial differentiation of stem cells and may be useful in promoting neurogenesis after stem cell transplantation.

Alzheimer Disease↗
PubMed2005

Scientific management of Mediterranean coastal zone: a hybrid ocean forecasting system for oil spill and search and rescue operations.

The oil spill from Prestige tanker showed the importance of scientifically based protocols to minimize the impacts on the environment. In this work, we describe a new forecasting system to predict oil spill trajectories and their potential impacts on the coastal zone. The system is formed of three main interconnected modules that address different capabilities: (1) an operational circulation sub-system that includes nested models at different scales, data collection with near-real time assimilation, new tools for initialization or assimilation based on genetic algorithms and feature-oriented strategic sampling; (2) an oil spill coastal sub-system that allows simulation of the trajectories and fate of spilled oil together with evaluation of coastal zone vulnerability using environmental sensitivity indexes; (3) a risk management sub-system for decision support based on GIS technology. The system is applied to the Mediterranean Sea where surface currents are highly variable in space and time, and interactions between local, sub-basin and basin scale increase the non-linear interactions effects which need to be adequately resolved at each one of the intervening scales. Besides the Mediterranean Sea is a complex reduced scale ocean representing a real scientific and technological challenge for operational oceanography and particularly for oil spill response and search and rescue operations.

Disaster Planning↗
PubMed2005

Memory immune response generated in Cercopithecus aethiops against meningococcal polysaccharide serogroup C conjugate vaccine.

The chemical conjugation of bacterial polysaccharide to carrier proteins has proved to be an efficient tool to improve the immunological response against these bacterial antigens. In this study, we characterized the antibody response generated in a non-human primate model against the meningococcal capsular polysaccharide serogroup C (CCPS) conjugated to the P64k protein. Similar to licensed vaccines the CCPS conjugate is able to generate a good memory immune response with antibody titers threefold higher than the free CCPS. Three different ELISA protocols were used to measure the antibody response and the importance of the coating antigen was demonstrated. The ELISA using the derivatized CCPS showed the best results and had a high correlation with the bactericidal activity. The antibodies elicited showed a high protective capacity when assayed in the infant rat protection model.

Animals↗
PubMed2005

Treatment of postoperative pain for burn patients with intravenous analgesia in continuous perfusion using elastomeric infusors.

INTRODUCTION: Postoperative pain after surgery with patients suffering from burns tends to be moderate or severe, and its treatment requires a combination of high-strength analgesics (opioids) with others having different action mechanisms according to the concept of multimodal analgesia. AIMS: In this article we propose the use of continuous intravenous analgesia with morphine using elastomeric infusors at fixed dose for the treatment of this kind of pain. An evaluation is made of its analgesic efficacy, side effects and level of satisfaction. MATERIAL AND METHODS: A study was made of 17 burn patients operated on in our unit who received continuous intravenous analgesia during the postoperative period, with morphine at 1mg/h, using elastomeric infusors for a period of 24h. Its analgesic efficacy was analysed using the visual analogical scale (VAS) at different moments; side effects and the level of acceptance by the patient was also evaluated. RESULTS: The results confirm a good analgesic effect after 2h from starting perfusion (VAS < 3). The side effects reveal a similar or lesser incidence to the use of morphine in bolus or using the PCA system, and in no cases did they require treatment to be halted. The level of acceptance of the procedure by patients was good. CONCLUSION: This method reveals a high level of analgesic efficacy in the postoperative period with burn patients in this study. However, it is important to note the lower results obtained in the first hours of perfusion, and proposing a heavy initial dose of analgesics when starting perfusion. This is presented as an efficient analgesic method that is easy to apply, has a low cost, and the possibility of extending its indications to ambulatory treatment.

Adolescent↗
PubMed2005

Long-term results of lung transplantation for emphysema.

INTRODUCTION: We sought to assess the differences between lung transplantation (LT) to treat emphysema, versus other pulmonary diseases. METHODS: This retrospective review of lung transplantations (LTs) performed from October 1993 to September 2003, included donor and recipient demographic data, pulmonary function, oxygenation, postoperative complications, incidence of rejection and pneumonia, and survival. RESULTS: Of 159 LTs performed the 39 transplanted to treat emphysema (24.4%), were in 33 men and 6 women of age 50.9 +/- 8.7 years (men, 25 to 65 years). There were differences between the emphysema vs other groups in terms of age (P < .001), gender (P = .001), need for bypass (P = .004), and immediate posttransplantation oxygenation index (P = .001). Perioperative mortality tended to be lower among patients with emphysema (2.7% vs 10.8%; P = .131). The incidences of complications and acute rejections was similar. Forced vital capacity, forced expiratory volume in 1 second, arterial oxygen tension, and arterial carbon dioxide tension improved significantly post-Tx. Actuarial survivals were 82%, 68%, and 63%, respectively, at 1, 3, and 7 years posttransplantation for emphysema patients vs 60%, 53%, and 42%, respectively, at 1, 3, and 7 years posttransplantation for non-emphysema patients (P = .049). CONCLUSION: Lung transplantation in patients with emphysema offers good long-term survival, with significant improvement in functional status and low morbidity. The older age of emphysema patients was not associated with a higher incidence of postoperative complications.

Adult↗
PubMed2005

Pediatric lung transplantation.

INTRODUCTION: Pediatric lung transplantation (LT) was started in Spain in 1996 at our institution. We compare the results of pediatric LT with those in adult patients. METHODS: A retrospective review of LT patients from 1993 to 2003 included demographic donor and recipient data, pulmonary function, gas exchange parameters, complications, episodes of rejection and pneumonia, as well as survival. Patients were divided into 2 groups: pediatric (<16 years) and adult (>16 years) LT patients. RESULTS: Of 165 LTs performed, 23 recipients were pediatric patients (10 boys, 13 girls; mean age, 11.9 +/- 2.9 years [range, 5-16 years]). The indications were cystic fibrosis (n = 21), pulmonary fibrosis (n = 1), and Kartagener syndrome (n = 1). The actuarial survival rate was 73%, 67%, and 62% at 1, 3, and 8 years post-LT in children, versus 67%, 56%, and 41% at 1, 3, and 8 years post-LT in adult patients (P = NS). Of the pediatric patients, 35% required mechanical ventilation preoperatively (P < .001). Pediatric patients showed a higher incidence of pneumonia (P < .01) and acute rejection episodes (P = .02) during the first month post-LT, and longer stays in the intensive care unit (P = .02). Pediatric patients displayed more immunosuppression-related adverse effects: diabetes (P = .04), neuropathy (P < .01), and hirsutism (P < .001). In children, arterial oxygen tension improved, from 51 mm Hg pre-LT to 93 mm Hg at 5 years post-LT. Forced expiratory volume in 1 second improved from 28% pre-LT to 84% at 5 years post-LT. CONCLUSION: In children, LT is a high-risk procedure because of the critical status of these patients. However, the results of pediatric LT are similar to those in adults, but with better long-term survival.

Adolescent↗
PubMed2005

Analysis of lung transplant recipients surviving beyond 5 years.

INTRODUCTION: We started lung transplantation (LT) in October 1993 and review the status of recipients who have survived beyond 5 years. METHODS: A retrospective review of patients undergoing LT from October 1993 to October 1998 included pulmonary function data, incidence of bronchiolitis obliterans syndrome (BOS), functional status, and survival. RESULTS: Of 73 transplantations 41 (56%) patients have survived beyond 5 years (study group), including 23 men and 18 women of age 33.2 +/- 15.6 years. Indications for LT were as follows: cystic fibrosis (n = 16), emphysema (n = 13), pulmonary fibrosis (n = 8), and other (n = 4). Actuarial survival at 5, 7, and 9 years was 56%, 53%, and 43%, respectively. Freedom from BOS was 63%, 56%, and 50% at 5, 7, and 9 years, respectively. The median percent predicted FEV1 was 67%, 56%, and 56%, respectively. Also, 79% of recipients had no limitations in their daily activities; 65% were active and working. Only 5% of patients showed some degree of limitation at 5 years posttransplantation. When survivors beyond 5 years were compared with nonsurvivors beyond 5 years, differences were observed: nonsurvivors more frequently required bypass (P = .01), experienced longer postoperative intubation times (P = .01), and exhibited lower PaO2 at 12 months posttransplantation (P < .01). CONCLUSION: Our data show good survival rates among patients surviving beyond 5 years after LT, with a moderate incidence of BOS at 9 years posttransplantation. Despite the incidence of BOS, these patients have good pulmonary function and activity status.

Actuarial Analysis↗
PubMed2005

Pulmonary tailoring and lobar transplantation to overcome size disparities in lung transplantation.

Size matching between donors and recipients represents one of the organ distribution criteria widely accepted by lung transplant teams. However, in some cases it is not possible to allocate a donor to the corresponding size-compatible recipient. To avoid possible complications derived from the implantation of oversized lungs into smaller recipients, surgical procedures such as pulmonary tailoring and lobar transplantation have been advocated. We review our experience in 13 patients undergoing volume reduction of the lung graft at the time of transplantation, either by nonanatomical lung volume reduction or by lobar transplantation. There were no significant differences between lung-downsized patients and standard lung transplantation patients in terms of donor characteristics, surgical and postoperative complications, functional outcome, and survival. We conclude that downsizing the lung graft either by nonanatomical resection or lobar transplantation is safe and reliable to overcome size disparities between donor and recipients, with no additional morbidity and with similar early and midterm outcomes to those in standard lung transplants.

ABO Blood-Group System↗
PubMed2005

Association between ACE gene I/D polymorphism and clinical presentation and prognosis of sarcoidosis.

Serum angiotensin converting enzyme (SACE) concentration is considered a marker of sarcoidosis activity. This concentration is influenced by an insertion/deletion (I/D) polymorphism of the ACE gene, such that SACE levels follow the pattern DD>ID>II. The aim of our work was to study the relationship between I/D polymorphism and susceptibility to sarcoidosis, as well as the relation between this polymorphism and the clinical presentation and evolution of the disease in 177 sarcoidosis patients. A group of 104 individuals without sarcoidosis was included as control. Genotyping was done by a polymerase chain reaction (PCR) method, and SACE concentration at diagnosis was determined by a kinetic method. No differences were observed in genotype or allele distributions between patients and controls, nor between patients considering the type of presentation (Löfgren versus non-Löfgren) and evolution of the disease (acute versus chronic). As reported for healthy populations, SACE concentrations followed the pattern DD>ID>II in sarcoidosis patients, but significant differences between genotypes existed only in the Löfgren group (p = 0.003) and in acute patients (p = 0.02). SACE concentrations at diagnosis were lower in acute patients (p = 0.05) and in Löfgren's syndrome (p = 0.04), but this seemed to occur only in ID individuals (p = 0.02 and p = 0.01, respectively). No relation was thus found between I/D polymorphism and susceptibility to sarcoidosis, but ACE I/D genotyping may improve the assessment of disease activity, both at diagnosis and during the follow-up of treated and untreated patients.

Female↗