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Biomedical subjects

David Jiménez

Publications and source records attributed to David Jiménez.

15 recordsLinked to original sources
PubMed2006

[Early complications in patients with pulmonary embolism].

BACKGROUND AND OBJECTIVE: Mortality, recurrences and hemorrhages are the most serious early complications of pulmonary embolism (PE). We intended to ascertain the frequency and mechanisms of complications within the first 10 days after PE was diagnosed. PATIENTS AND METHOD: We included patients suspected of suffering PE between December 2003 and August 2004 from 8 hospitals. We performed a multicenter observational prospective study of 8 Spanish hospitals with consecutive outpatients diagnosed with PE. Database of clinical variables: computerized Registry of Patients with Venous Thromboembolism (RIETE). Statistic analysis included chi2 and Student's t test to compare the 2 groups of patients (with and without complications). RESULTS: Six hundred eighty one patients were included, 336 men and 345 women (mean age 66 and 70, respectively). During the first 10 days, 33 (4.8%) of them died, and 22 (3.2%) had an hemorrhage yet no recurrences appeared. Previous immobilization and the presence of respiratory failure, cancer or renal failure were significantly associated with early complications while previous surgery and thoracic pain were not associated with those. CONCLUSIONS: Early complications and some of the associated factors were in agreement with published data. Other situations such as previous surgery or thoracic pain appeared to be protective factors.

Aged↗
PubMed2006

Pulmonary embolism in patients with chronic obstructive pulmonary disease or congestive heart failure.

BACKGROUND: The diagnosis of pulmonary embolism (PE) is often unreliable in patients with chronic obstructive pulmonary disease (COPD) or congestive heart failure (CHF). SUBJECTS AND METHODS: Registro Informatizado de la Enfermedad TromboEmbólica (RIETE) is an ongoing registry of consecutive patients with acute venous thromboembolism. In this study, the clinical characteristics, laboratory findings, and clinical outcomes of all enrolled patients with acute PE, with or without underlying cardiopulmonary diseases, were compared and contrasted. In addition, the performance of 2 clinical models for the diagnosis of PE was retrospectively evaluated. RESULTS: As of January 2005, 4444 patients with symptomatic PE have been enrolled in RIETE. Of those, 632 patients (14%) had COPD and 422 (9.5%) had CHF. Significant differences were found in clinical presentation and 3-month outcomes among the 3 groups. With the Geneva model, there was a lower percentage of PE patients with COPD (relative risk [RR] 0.82; 95% confidence interval [CI], 0.66-1.02) or CHF (RR 0.73; 95% CI, 0.56-0.95) who fell into the low pretest probability category, compared with patients with neither. Besides, the percentage of patients with high probability of PE was similar among the 3 patient groups. The frequency of COPD (61%) and CHF (72%) patients with a high pretest probability for PE increased when using the Pisa score, but the percentage of COPD patients into the high probability group was lower (RR 0.60; 95% CI, 0.51-0.71). CONCLUSIONS: Significant differences exist in PE patients with and without underlying cardiopulmonary diseases. The performance of the 2 clinical prediction models varied according to the presence or absence of underlying COPD or CHF.

Diagnosis, Differential↗
PubMed2006

[Thromboembolic events in patients after a negative computed tomography pulmonary angiogram: A retrospective study of 165 patients].

OBJECTIVE: To determine the value of computed tomography (CT) angiography of the chest as a diagnostic test to exclude pulmonary embolism and to assess compliance with diagnostic protocols for thromboembolic disease. PATIENTS AND METHODS: We retrospectively studied patients who underwent CT angiography of the chest because of suspected pulmonary embolism in 2004. All the patients were followed for 3 months. The percentage of patients diagnosed with a thromboembolic event based on an objective test during the follow-up period was determined. We analyzed the percentage of patients with a negative CT angiogram on whom additional diagnostic tests (ultrasound of the lower limbs and/or ventilation-perfusion lung scintigraphy) were performed. RESULTS: One hundred sixty-five patients underwent CT angiography of the chest because of suspected pulmonary embolism in 2004. Four of the patients were excluded from the study because they were on chronic anticoagulation therapy and a further 2 were excluded because they had a life expectancy of under 3 months. Of the remaining 159 patients, 60 had CT angiograms that were interpreted as high probability for pulmonary embolism (prevalence of 38%). Thirty-nine of the 99 patients with a negative CT angiogram experienced an objectively confirmed thromboembolic event (63% sensitivity; 95% confidence interval, 53%-73%). Other diagnostic tests were not performed in 46% of the cases. CONCLUSIONS: In our setting, a negative single-detector helical CT angiogram was not sensitive enough to exclude the diagnosis of pulmonary embolism. Furthermore, compliance with internationally accepted diagnostic protocols was far from optimal.

Aged↗
PubMed2006

The risk of recurrent venous thromboembolism in patients with unprovoked symptomatic deep vein thrombosis and asymptomatic pulmonary embolism.

Patients with a first episode of symptomatic pulmonary embolism (PE) have a higher risk of recurrent venous thromboembolism (VTE) than patients with a first episode of proximal lower extremity deep vein thrombosis (DVT). Patients with symptomatic DVT and silent PE may have a different risk of VTE recurrence than patients that have symptomatic DVT without PE. Therefore, it was the aim of this prospective cohort study to compare the risk of recurrent symptomatic VTE in patients with proximal lower extremity DVT and silent PE to the risk in patients that only have proximal lower extremity DVT. Ninety-one consecutive outpatients presenting to the emergency department of a university hospital subsequently hospitalised with a first episode of unprovoked symptomatic proximal lower extremity DVT, and without new pulmonary symptoms were included. Standard initial treatment consisted of intravenous unfractionated heparin or subcutaneous low-molecular-weight heparin for 5-7 days, overlapped with oral vitamin-K antagonist therapy, with long-term oral vitamin-K antagonist therapy (goal INR 2.5 [2.0-3.0]). Study endpoints were: symptomatic recurrent DVT, new PE, and recurrent PE, evaluated by standard objective testing. At enrollment, 28 of 91 (31%) patients with DVT had silent PE. In the patients with DVT and silent PE, there were 3 VTE recurrences during 20 person-years of follow-up, while there were no VTE recurrences during 61 person-years of follow- up in the patients with isolated DVT. The Kaplan-Meier estimated VTE recurrence rate at 1 year after the diagnosis of DVT was 11% (95% CI: 2-28%) for patients with symptomatic DVT and silent PE, compared to 0% in patients with isolated symptomatic DVT (p=0.0045). In patients with a first episode of unprovoked symptomatic acute proximal lower extremity DVT, the risk of recurrent VTE was significantly higher in those with silent PE compared to those without PE.

Aged↗
PubMed2005

Etiology and prognostic significance of massive pleural effusions.

It has been stated that malignancy is the most common aetiology of massive pleural effusions. To determine the most frequent causes of massive pleural effusions and to assess the diagnostic yield of different diagnostic procedures and survival, we prospectively studied 1084 patients with pleural effusion. Massive pleural effusions were identified in 121 of 1084 patients (11.2%). Compared with non-massive pleural effusions, massive pleural effusions were significantly more likely to be malignant (53.7% vs. 38.3%, P=0.03) or secondary to cirrhosis (9.9% vs. 2.6%, P=0.0000). On the other hand, massive pleural effusions were significantly less likely to be secondary to infection (10.7% vs. 19.2%, P=0.003) or congestive heart failure (0.8% vs. 6.7%, P=0.03). There was a significant increase in the yield of diagnostic studies in patients with massive malignant pleural effusions (56.9% for cytological studies and 36.9% for biopsies). On the other hand, there was no difference in the diagnostic yield of microbiological and histological studies in the group of tuberculous pleural effusions. In our study population, patients with non-massive malignant pleural effusions had a significantly better survival than those with massive malignant pleural effusions, with a median survival of 8 months (95% confidence interval, 7-9) compared with 5 months (95% confidence interval, 4-6) (P=0.0009). We conclude that malignancy is the most common cause of a massive exudative effusion. Massive malignant pleural effusions are associated with worse survival, independent of age and histologic subgroup, than are non-massive malignant pleural effusions.

Adult↗
PubMed2005

The alpha-glucanase Agn1p is required for cell separation in Schizosaccharomyces pombe.

BACKGROUND INFORMATION: In animal cells, cytokinesis occurs by constriction of an actomyosin ring. In fission yeast, ring constriction is followed by deposition of a multilayered division septum that must be cleaved to release the two daughter cells. Although many studies have focused on the actomyosin ring and septum assembly, little is known about the later steps involving the cleavage of the cell wall. RESULTS: We identified a novel gene in Schizosaccharomyces pombe, namely the agn1(+) gene that has homology to fungal 1,3-alpha-glucanases (mutanases). Disruption of the agn1(+) gene is not lethal to the cells, but does interfere with their separation, whereas overexpression of Agn1p is toxic and causes cell lysis. Agn1p levels reach a peak during septation and the protein localizes to the septum region before cell separation. Moreover, agn1(+) is responsible for the 1,3-alpha-glucanase activity, which shows a maximum at the end of septation. CONCLUSIONS: Our results clearly suggest the existence of a relationship between agn1(+), 1,3-alpha-glucanase activity and the completion of septation in S. pombe. Agn1p could be involved in the cleavage of the cylinder of the old wall that surrounds the primary septum, a region rich in alpha-glucans.

Cell Division↗
PubMed2004

Contribution of N-linked glycans to the conformation and function of intercellular adhesion molecules (ICAMs).

The crystal structures of the glycosylated N-terminal two domains of ICAM-1 and ICAM-2 provided a framework for understanding the role of glycosylation in the structure and function of intercellular adhesion molecules (ICAMs). The most conserved glycans were less flexible in the structures, interacting with protein residues and contributing to receptor folding and expression. The first N-linked glycan in ICAM-2 contacts an exposed tryptophan residue, defining a conserved glycan-W motif critical for the conformation of the integrin binding domain. The absence of this motif in human ICAM-1 exposes regions used in receptor dimerization and rhinovirus recognition. Experiments with soluble molecules having the N-terminal two domains of human ICAMs identified glycans of the high mannose type N-linked to the second domain of the dendritic cell-specific ICAM-grabbing nonintegrin lectin-ligands ICAM-2 and ICAM-3. About 40% of those receptor molecules bear endoglycosidase H sensitive glycans responsible of the lectin binding activity. High mannose glycans were absent in ICAM-1, which did not bind to the lectin, but they appeared in ICAM-1 mutants with additional N-linked glycosylation and lectin binding activity. N-Linked glycosylation regulate both conformation and immune related functions of ICAM receptors.

Amino Acid Motifs↗
PubMed2002

Tangential migration in neocortical development.

During cortical development, different cell populations arise in the basal telencephalon and subsequently migrate tangentially to the neocortex. However, it is not clear whether these cortical cells are generated in the lateral ganglionic eminence (LGE), the medial ganglionic eminence (MGE), or both. In this study, we have generated a three-dimensional reconstruction to study the morphological formation of the two ganglionic eminences and the interganglionic sulcus. As a result, we have demonstrated the importance of the development of these structures for this tangential migration to the neocortex. We have also used the tracers DiI and BDA in multiple experimental paradigms (whole embryo culture, in utero injections, and brain slice cultures) to analyze the routes of cell migration and to demonstrate the roles of both eminences in the development of the cerebral cortex. These results are further strengthened, confirming the importance of the MGE in this migration and demonstrating the early generation of tangential migratory cells in the LGE early in development. Finally, we show that the calcium-binding protein Calretinin is expressed in some of these tangentially migrating cells. Moreover, we describe the spatiotemporal sequence of GABA, Calbindin, and Calretinin expression, showing that these three markers are expressed in the cortical neuroepithelium over several embryonic days, suggesting that the cells migrating tangentially form a heterogeneous population.

Animals↗
PubMed2002

Sterols in erg mutants of Phycomyces: metabolic pathways and physiological effects.

Phycomyces is a fungal producer of beta-carotene and other beneficial metabolites. Several erg mutants of Phycomyces, originally selected to study the effects of membrane alteration on physiological responses, have now been used to gain information about sterol biosynthesis in filamentous fungi. One mutant, H23, and its progeny were found to be blocked at episterol C-5 dehydrogenase and did not produce ergosterol or any other sterol with a conjugated Delta(5,7) diene system. This mutant showed abnormal phototropism, which was correlated with the altered sterol composition. Another mutant, H25, seems to be a regulatory mutant. All analyzed mutants synthesized ergosta-7,22,24(28)-trien-3beta-ol, demonstrating for the first time that the sterol C-22 dehydrogenase of Phycomyces is capable of recognizing sterols with a 24(28) unsaturated side chain. New evidence regarding the biogenesis of neoergosterol and phycomysterols, the potential sparking function of cholesterol, as well as the regulation of sterol biosynthesis in this fungus is also reported. Given these results, a pathway for sterol biosynthesis in Phycomyces is proposed.

Amphotericin B↗
PubMed2002

Percutaneous aortic valvoplasty in congenital aortic valvar stenosis.

OBJECTIVE: To evaluate immediate and midterm results with percutaneous aortic valvoplasty. MATERIAL AND METHODS: We reviewed the records of 141 patients undergoing percutaneous aortic valvopasty over a period of 13 years. RESULTS: The patients were aged from 2 months to 40 years, with a mean of 10.9 +/- 9.9 years. Of the total, 90 (63+/%) were male. The initial systolic peak-to-peak gradient decreased from 163 +/- 52 mmHg to 32 +/- 18 mmHg (p < 0.01) after valvoplasty in all 141 patients, while the proportional reduction ranged from 0 to 100%, with a mean of 72 +/- 27%. The index of the size of the balloon to the diameter of the valvar orifice was 0.88 +/- 0.19 in 128 patients. The follow-up ranged from 6 to 168 months, with a mean 51 +/- 48 months in 70 patients. A significant difference was found in those failing after dilation when the initial evaluation was compared to the final evaluation of patients with follow-up. In those failing, the number of patients rose from 12 (17%) to 21 (30%) (p < 0.01). In contrast, in those in whom we achieved success, there was not such a great difference between the initial and final evaluation: 58 (83%) versus 49 (70%) (p < 0.1). The actuarial freedom curve of patients not needing new percutaneous aortic valvoplasty or surgery, by 182 months, was at 87% and 82% respectively. CONCLUSION: We have reviewed the largest series of patients in Latin-America reported thus far after undergoing percutaneous aortic valvoplasty, concentrating on mid term follow-up and limitations. New prospective and multicentric studies are needed from our region.

Adolescent↗
PubMedDate not supplied

Incidence of air travel-related pulmonary embolism at the Madrid-Barajas airport.

BACKGROUND: Prolonged air travel and the associated immobilization are risk factors for venous thromboembolism. The occurrence of pulmonary thromboembolism (PTE) under these circumstances is referred to as economy class syndrome. We assessed the incidence of symptomatic PTE in passengers on long-haul flights arriving at Madrid-Barajas Airport, Madrid, Spain, and the association with the number of flight hours. METHODS: We retrospectively reviewed cases of PTE among international travelers arriving at Madrid-Barajas Airport between January 1995 and December 2000. Patients presenting with symptoms of deep venous thrombosis but without symptoms of PTE were excluded. Pulmonary thromboembolism was identified using an algorithm of diagnostic tests. The incidence of PTE and the association with flight duration was assessed. RESULTS: The average number of passengers per year who arrived at the airport on flights originating abroad in the period analyzed was 6 839 222. Sixteen cases of PTE were detected over the 6-year period. All patients with travel-associated PTE had flight durations of greater than 6 hours. The overall incidence of PTE was 0.39 per 1 million passengers (95% confidence interval [CI], 0.20-0.58). On flights that lasted between 6 and 8 hours, the incidence was 0.25 per 1 million passengers (95% CI, 0-0.75), while on flights longer than 8 hours, the incidence was 1.65 per 1 million passengers (95% CI, 0.81-2.49) (P<.001). CONCLUSIONS: Air travel is a risk factor for PTE, and the incidence of PTE increases with the duration of the air travel. However, the low incidence of PTE among long-distance passengers, similar to that observed in other international airports, does not justify social alarm.

Aged↗
PubMedDate not supplied

Types of obstructions in double-chambered right ventricle: mid-term results.

BACKGROUND: The double-chambered right ventricle (DCRV) is increasingly recognized as a distinct obstruction entity. The nature of the obstruction is not well defined. METHODS: Patients with DCRV were prospectively studied during the last 4 years according to the following criteria: 1) pressure gradient by echo Doppler and cardiac catheterization within the right ventricle; 2) angiographic demonstration, and 3) surgical confirmation. RESULTS: From March 1997 to March 2001, 10 new cases were included. Age ranged from 2 to 14 years (mean 9.5 +/- 4.4 years), weight ranged from 9.9 to 75 kg (mean 23 +/- 13.6 kg), and height from 0.85 to 1.48 m (mean 114 +/- 19 cm). Systolic gradient by echo Doppler ranged from 20 to 135 mmHg (mean 86 +/- 44 mmHg) and by cardiac catheterization, 18 to 130 mmHg (mean 78 +/- 35 mmHg). In terms of angiographic findings, in six patients the right ventriculogram showed an oblique and low obstruction; in four patients the obstruction was high and horizontal. With regard to surgical findings, angiographic findings were confirmed by the surgeon except in one patient, in whom both types of obstruction were present. No mortality was observed. With follow-up 4 to 40 months after surgery (mean 24 +/- 15 months), 8 of 10 patients were evaluated; all corresponded to class I NYHA. Systolic gradient by echo Doppler ranged from 0 to 11 mmHg (mean 4 +/- 6 mmHg). CONCLUSIONS: DCRV IS PRODUCED BY THE FOLLOWING THREE TYPES OF MUSCULAR OBSTRUCTIONS: low and oblique obstruction; high and horizontal obstruction, and mixed obstruction. Mid-term surgical results are satisfactory.

Adolescent↗
PubMedDate not supplied

Origin of the cortical layer I in rodents.

Using birthdating techniques, we have studied when cells that settle in the marginal zone (future layer 1) of the cortical neuroepithelium are generated in developing rat embryos. The majority of marginal zone cells are generated at embryonic day 12 (E12), E13 and E14, although some cells generated later can incorporate into this stratum after the cortical plate forms. The nature and the origin of the cell populations that colonize the preplate/marginal zone was studied by means of immunohistochemistry using cell markers for gamma-amino butyric acid (GABA), reelin and the calcium binding proteins calretinin and calbindin. At early stages of development, the preplate is formed by Cajal-Retzius cells, subplate cells, subpial granular layer cells, some interneurons and some glial cells. With the arrival of the cortical plate cells, the subplate cells descend to occupy the stratum below. Layer 1 cells are of diverse origin as some of them are generated in the ventricular zone of the cortical neuroepithelium, whereas other cell populations come from extracortical regions such as the olfactory placode or the ganglionic eminences of the basal telencephalon. The predominant cell type in the marginal zone is the Cajal-Retzius cell, which expresses reelin and calretinin, and is probably generated in the cortical neuroepithelium. These cells can be readily distinguished from cells that come from the ganglionic eminences as these later populations mainly express GABA and calbindin. Finally, our results suggest that the cells of the subpial granular layer might be generated in the rostral pole of the lateral ganglionic eminences.

Animals↗