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Biomedical subjects

A Pacheco

Publications and source records attributed to A Pacheco.

At least 19 recordsLinked to original sources
PubMed2006

Vascular endothelial cadherin regulates vascular permeability: Implications for ovarian hyperstimulation syndrome.

CONTEXT: Ovarian hyperstimulation syndrome (OHSS) is an iatrogenic complication of treatment with fertility drugs. It is characterized by increased vascular permeability and simultaneous overexpression of vascular endothelial growth factor (VEGF) in ovarian cells. OBJECTIVE: We tested the hypothesis that the endothelium and endothelial cell-to-cell junctions are downstream targets of VEGF during OHSS pathogenesis. We investigated the potential involvement of vascular endothelial (VE)-cadherin, an interendothelial adhesion molecule, in the capillary hyperpermeability in OHSS. DESIGN: Human endothelial cells from umbilical veins (HUVEC) were used as an in vitro model of OHSS. INTERVENTION: Cell cultures were treated with varying doses of estradiol (E2), human chorionic gonadotropin (hCG), VEGF, and antihuman VEGF antibodies, either alone or in combination, and the effect on VE-cadherin release was evaluated at different time points. Permeability assays were performed using fluoresceinisothiocyanate-labeled albumin, and actin filaments rearrangement was evaluated by fluorescent microscopy. RESULTS: Culturing of HUVEC with high doses of E2 produced no significant changes in VE-cadherin concentration, but hCG and VEGF produced a significant increase in VE-cadherin release. Time-course experiments showed that VE-cadherin was secreted 12 h after VEGF addition. Antihuman VEGF antibodies prevented these changes. Permeability assays demonstrated that, although E2 did not alter the arrangement of HUVEC in vitro, hCG and VEGF caused changes in the actin fibers indicative of increased capillary permeability. VEGF also induced an increase in paracellular permeability of HUVEC at the same doses used in the previous experiments. CONCLUSIONS: Adhesion molecules like VE-cadherin may play a role in the development and progression of increased capillary permeability in severe OHSS.

Antigens, CD↗
PubMed2006

Drinking water biofilm assessment of total and culturable bacteria under different operating conditions.

Monitoring of biofilms subjected to different operating conditions was performed using a flow cell system. The system was fed by chlorine-free tap water, with and without added nutrients (0.5 mg l(-1) carbon, 0.1 mg l(-1) nitrogen and 0.01 mg l(-1) phosphorus), and biofilms were grown on polyvinyl chloride (PVC) and stainless steel (SS) coupons, both in laminar and turbulent flow. The parameters analysed were culturable cells, using R2A, and total bacteria, which was assessed using the 4,6-diamino-2-phenylindole (DAPI) staining method. The impact of the different operating conditions in the studied parameters was established using Multivariate Analysis of Variance (MANOVA). From the most relevant to the least relevant factor, the total and culturable bacteria in biofilms increased due to the addition of nutrients to water (F = 20.005; p < 0.001); the use of turbulent (Re = 11000) instead of laminar (Re = 2000) hydrodynamic flows (F = 9.173; p < 0.001); and the use of PVC instead of SS as the support material (F = 2.848; p = 0.060). Interactions between these conditions, namely between surface and flow (F = 8.235; p < 0.001) and also flow and nutrients (F = 5.498; p < 0.05) have also proved to significantly influence biofilm formation. This work highlights the need for a deeper understanding of how the large spectrum of conditions interact and affect biofilm formation potential and accumulation with the final purpose of predicting the total and culturable bacteria attached to real drinking water distribution pipes based on the system characteristics.

Biofilms↗
PubMed2005

Urgent lung transplantation in Spain.

BACKGROUND: Lung donors are scarce and lung transplantation resources are limited. Because urgent lung transplantation (ULT) is assumed to yield poor results, its use is controversial. We assessed the outcome of patients who received ULT seeking to determine effectiveness and risk factors. PATIENTS AND METHOD: We collected data from every ULT performed in Spain during 5 years (1998-2002). The survival of patients was studied using Kaplan-Meier, Cox regression, and chi-square statistical analyses. We compared outcomes and perioperative mortality (over 30 days) for ULT procedures, analyzing the influence of certain variables (age, type of transplant, diagnosis, indication, and time on waiting list). RESULTS: Among 109 patients proposed for the procedure, 73 ULT were performed during the period. The most frequent indications were pulmonary fibrosis (19 cases) and cystic fibrosis (19 cases), showing the worst and the better survival rates, respectively. The bad prognosis, determined mainly by per operative mortality rate (35.62%), was significantly affected by age (worse for patients older than 40 years) and type of LT (single worse than double; P < .05). A longer time waiting for ULT also showed a worse prognosis (P < .005). CONCLUSIONS: Long-term survival after ULT shows that the procedure is effective and efficient for a select group of patients, despite the high per operative risk. ULT should be reserved for younger patients. It also requires performance in a short period (just a few days), initially rejecting a single lung transplant, provided that the patient is adequately monitored.

Humans↗
PubMed2004

Coasting acts through downregulation of VEGF gene expression and protein secretion.

BACKGROUND: This study was conducted to investigate the mechanisms by which coasting may be effective in decreasing the incidence of ovarian hyperstimulation syndrome (OHSS). METHODS: A total of 160 women (patients and oocyte donors) undergoing coasting and 116 controls were included in the study. Serum, follicular fluid and granulosa cells were collected on the day of oocyte retrieval. Vascular endothelial growth factor (VEGF) concentrations were determined using an enzyme-linked immunosorbent assay (ELISA). Real-time PCR was performed to evaluate VEGF gene expression in granulosa cells. Cell death was studied by flow cytometry using annexin V-fluorescein isothiocyanate (FITC) and counterstaining by propidium iodide, and double staining with CD45 monoclonal antibody was performed to distinguish the contamination of apoptotic leukocytes. RESULTS: Follicular cells aspirated from coasted patients showed a ratio in favour of apoptosis, especially in smaller follicles (48 versus 26%, P < 0.05). Follicular fluid determinations confirmed that coasting reduces VEGF protein secretion (1413 versus 3538 pg/ml, P < 0.001) and gene expression (2-fold decrease) in granulosa cells. Follicular fluid VEGF protein levels positively correlated with follicular size (r = 0.594, P = 0.001) and estradiol production (r = 0.558, P = 0.038). Women who underwent coasting showed a comparable IVF cycle outcome; however, a higher cancellation rate was found in cycles that were coasted. CONCLUSIONS: Coasting affects all follicles through apoptosis, especially immature follicles, without affecting oocyte/endometrial quality. The significant decrease found in VEGF expression and secretion explains why coasting is clinically effective in reducing the incidence and severity of OHSS.

Down-Regulation↗
PubMed2004

Extended coasting duration exerts a negative impact on IVF cycle outcome due to premature luteinization.

Coasting, or withholding gonadotrophin administration while maintaining gonadotrophin-releasing hormone analogue until oestradiol drops to a safe concentration, is an alternative approach to prevent ovarian hyperstimulation syndrome (OHSS) in high responder patients. However, the length of this procedure has not been precisely studied. This paper is a retrospective study of 132 patients who showed a high response (oestradiol > 4500 pg/ml and/or more than 20 follicles > 17 mm) to ovarian stimulation and were coasted due to their high risk of developing OHSS, and evaluated the impact of the duration of coasting on IVF cycle outcome. Additionally, serum LH and progesterone concentrations were studied to investigate whether premature luteinization was present in these cycles and whether it might be related to coasting duration. A significant decrease in implantation rate was found when coasting was required for more than 4 days, together with a trend towards a higher cancellation rate. Premature luteinization was significantly elevated in women undergoing coasting compared with control women (34 versus 15.6%, P < 0.05). In the majority of patients who showed premature luteinization, coasting lasted >/=3 days. To conclude, prolonged coasting may affect the endometrium, anticipating the implantation window. These data may explain why some women undergoing extended coasting show a lower implantation rate compared with controls.

Adult↗
PubMed2003

[Asthmatic characteristics in smokers with advanced emphysema].

OBJECTIVES: Most pneumologists assume that chronic asthma and emphysema associated with smoking differ both in their etiology and type of inflammation. However, it is difficult to study subjects who have both diseases simultaneously. We designed a prospective study to determine whether or not some advanced emphysema patients who are smokers have an asthmatic profile suggesting the two diseases overlap. PATIENTS AND METHOD: Twenty-three smokers with moderate to severe obstruction and radiologic signs of advanced emphysema were studied. The following signs of asthma were analyzed for all patients: positive acute response to bronchodilators, eosinophilia in peripheral blood, significant eosinophilia in sputum, significant total serum immunoglobulin E (IgE) and specific IgE positive for common allergens and fungi. An asthmatic profile was defined as the presence of 3 or more of the aforementioned signs. Statistical analysis was by calculation of the confidence interval on the total number of positive cases to estimate the population percentage. RESULTS: Data on at least 4 characteristics were available for 21 of the 23 patients. Ten (48%) of the 21 had asthmatic profiles (3 or more of the aforementioned characteristics). This finding suggests that asthmatic characteristics are present in between 17.6 and 79.6% of the studied population with advanced emphysema, with a confidence interval of 99.9%. CONCLUSIONS: We conclude that emphysema initially associated with smoking may mean that at least 17.6% of patients have a clear asthmatic profile, which indicates a high degree of overlap between asthma and emphysema in smokers. Thus, our findings are consistent with the Dutch theory that chronic obstructive diseases have a common origin in underlying allergic sensitization and bronchial hyperresponsiveness alongside various other influential factors such as tobacco smoking over the course of disease.

Administration, Inhalation↗
PubMed2003

[Usefulness of thoracic radiography after insertion of transitory catheters for hemodialysis].

A chest X-ray has been routinely used to evaluate possible complications of a catheter installed for hemodialysis. The objective of the present study was to evaluate the utility of routine chest X-ray to detect complications derived from the installation of temporary catheters through a jugular vein access. We studied prospectively 95 successive jugular catheters for hemodialysis. After installation the operator answered a questionnaire that asked for details of the procedure and his opinion of the utility of a chest X-ray to detect a complication in each particular case. A chest X-ray was done in every patient and analyzed blindly. There were 17 minor complications: 7 arterial punctures, 5 neck hamatomas and 5 malpositions of catheters. No major complications were found. Sixty per cent of the catheters that required three or more punctures had a complication vs only 10% of the ones that required two or less puncture (p < 0.05). In five occasions the catheters were malpositioned, in four of these cases a complication was suspected. The wire guide was twisted in all of these cases. The procedure was considered of medium or high difficulty in four of the five malpositioned catheters, in contrast a medium or highly difficult case was considered only in 13 of the 90 well positioned catheters (p < 0.05). The time employed for the catheters installation was significantly higher for the malpositioned catheters. In 29.5% of the cases the operator considered a chest X-ray necessary, 2/3 of the cases did not have a well founded clinical suspicion of complication. We conclude that routine chest X-ray after installation of a jugular catheter for hemodialysis has a low diagnostic value for the detection of complications derived from the procedure and should be ordered only when clinical features suggest a complication.

Catheterization, Central Venous↗
PubMed2001

Rapid genetic selection of inhibitor-resistant protease mutants: clinically relevant and novel mutants of the HIV protease.

Site-specific proteolysis is an important regulatory mechanism in many basic cellular processes as well as playing critical roles in the life cycle of viruses and other pathogenic organisms. For the human immunodeficiency virus (HIV) the encoded protease is required for the replication of the virus and has been the target of novel antiviral therapeutics. However, the emergence of inhibitor-resistant viral strains has become an increasingly significant clinical problem. Using a bacteriophage-based genetic selection, a bank of inhibitor-resistant mutants in this protease has been isolated that includes mutations that correlate with resistant clinical isolates. The rapid selection of such mutations has implications for the prediction of relevant mutations and may be applicable to other viral systems.

Bacteriophage lambda↗
PubMed2001

Bronchiolitis obliterans organizing pneumonia associated with Evans syndrome.

The association of bronchiolitis obliterans organizing pneumonia (BOOP) with insulin-dependent diabetes mellitus (IDDM) and Evans syndrome (autoimmune pancytopenia) has not been reported previously. We describe the case of a 4-year-old child diagnosed with IDDM and Evans syndrome who presented malaise, fever and nonproductive cough for several months. The chest radiograph revealed several patchy alveolar opacities with peripheral and bilateral distribution and multiple hilar and mediastinal adenopathies. An open lung biopsy established the diagnosis of BOOP. During the follow-up over the next 7 years, the patient had chronic relapses in spite of corticosteroid treatment and developed restrictive lung disease.

Autoimmune Diseases↗
PubMed2000

An MCD spectroscopic study of the molybdenum active site in sulfite oxidase: insight into the role of coordinated cysteine.

Temperature-dependent magnetic circular dichroism (MCD) spectroscopy has been used for the first time to probe the electronic structure of the Mo active site in sulfite oxidase (SO). The enzyme was poised in the catalytically relevant [Mo(V):Fe(II)] state by anaerobic reduction of the enzyme with the natural substrate, sulfite, in the absence of the physiological oxidant cytochrome c. The [Mo(V):Fe(II)] state is of particular importance, as it is proposed to be a catalytic intermediate in the oxidative half reaction, where SO is reoxidized to the resting [Mo(VI):Fe(III)] state by two sequential one-electron transfers to cytochrome c. The MCD spectrum of the enzyme shows no charge transfer transitions below approximately 17000 cm(-1). This has been interpreted to result from (1) a severe reduction in ene-1,2-dithiolate sulfur in-plane and out-of-plane p orbital mixing, (2) a decrease in the dithiolate sulfur out-of-plane p-Mo d(xy) orbital overlap, and (3) an orthogonal orientation between the vertical cysteine sulfur p (perpendicular to the Mo-Scys sigma-bond) and Mo d(xy) orbitals. The spectroscopically determined cysteine sulfur p-Mo d(xy) bonding scheme in the [Mo(V):Fe(II)] state is consistent with the crystallographically determined O-Mo-Scys-C dihedral angle of approximately 90 degrees and precludes a covalent interaction between the vertical cysteine sulfur p orbital and Mo d(xy), effectively decoupling the cysteine from an effective through-bond electron transfer pathway. We have tentatively assigned a 22250 cm(-1) positive C-term feature in the MCD as the cysteine S(sigma)-->Mo d(xy) charge transfer that becomes allowed by a combination of configuration interaction and low-symmetry; however, the orbital overlap is anticipated to be quite small due to the near orthogonality of these orbitals. Therefore, we propose that the primary role of the coordinated cysteine is to decrease the effective nuclear charge on Mo by charge donation to the metal, statically poising the active site at more negative reduction potentials during electron transfer (ET) regeneration. Finally, the results of this study are consistent with the pyranopterin ene-1,2-dithiolate acting to couple the Mo site into efficient superexchange pathways for ET regeneration following oxygen atom transfer to the substrate.

Animals↗
PubMed2000

Primary cutaneous CD30-positive large cell lymphoma.

Primary cutaneous CD30-positive large cell lymphoma is a recently described entity, recognized by immunohistochemical criteria. Spontaneous regression may occur and although relapses are frequent, most patients have a favourable prognosis. We describe a 83-year-old woman with a large ulcerated tumour on her right forearm, with 2 months evolution. Histological and immunohistochemical examination revealed a CD30-positive large cell lymphoma. Systemic involvement was not detected. The tumour regressed spontaneously. Cutaneous relapses occurred one year later, all with spontaneous regression. After a 2-year follow-up period, the patient is well, without concurrent extracutaneous disease. This case is in keeping with other reports of spontaneous regression and favourable outcome of this type of cutaneous lymphoma.

Aged↗
PubMed2000

Irritant-induced asthma: clinical and functional aspects.

We report on three patients who experienced persistent asthma symptoms after repetitive irritant exposure which took place over a period from several days to months. Airway inflammation was assessed by induction of sputum and functional follow-up information was obtained from serial lung function tests. All patients had bronchial hyperresponsiveness to methacholine at the time of diagnosis. However, induced sputum samples did not show increased differential count of eosinophils. Treatment with inhaled corticosteroids was started in all of the patients and two of them were removed from work. In the two patients who left the workplace, methacholine inhalation test became negative when symptoms disappeared, whereas the patient who continued working had persistent asthma symptoms and a deterioration of bronchial hyperresponsiveness.

Adult↗
PubMed1999

The pH dependence of intramolecular electron transfer rates in sulfite oxidase at high and low anion concentrations.

The individual rate constants for intramolecular electron transfer (IET) between the Mo(VI)Fe(II) and Mo(V)Fe(III) forms of chicken liver sulfite oxidase (SO) have been determined at a variety of pH values, and at high and low anion concentrations. Large anions such as EDTA do not inhibit IET as dramatically as do small anions such as SO4(2-) and Cl-, which suggests that specific anion binding at the sterically constrained Mo active site is necessary for IET inhibition to occur.IET may require that SO adopt a conformation in which the Mo and Fe centers are held in close proximity by electrostatic interactions between the predominantly positively charged Mo active site, and the negatively charged heme edge. Thus, small anions which can fit into the Mo active site will weaken this electrostatic attraction and disfavor IET. The rate constant for IET from Fe(II) to Mo(VI) decreases with increasing pH, both in the presence and absence of 50 mM SO4(2-) . However, the rate constant for the reverse process exhibits no significant pH dependence in the absence of SO4(2-), and increases with pH in the presence of 50 mM S04(2-). This behavior is consistent with a mechanism in which IET from Mo(V) to Fe(III) is coupled to proton transfer from Mo(V)-OH to OH-, and the reverse IET process is coupled to proton transfer from H2O to Mo(VI) = O. At high concentrations of small anions, direct access of H2O or OH- to the Mo-OH will be blocked, which provides a second possible mechanism for inhibition of IET by such anions. Inhibition by anions is not strictly competitive, however, and Tyr322 may play an important intermediary role in transferring the proton when an anion blocks direct access of H2O or OH- to the Mo-OH. Competing H-bonding interactions of the Mo-OH moiety with Tyr322 and with the anion occupying the active site may also be responsible for the well-known equilibrium between two EPR-distinct forms of SO that is observed for the two-electron reduced enzyme.

Anions↗
PubMed1999

Femtosecond spectroscopic observations of initial intermediates in the photocycle of the photoactive yellow protein from Ectothiorhodospira halophila.

Femtosecond time-resolved absorbance measurements were used to probe the subpicosecond primary events of the photoactive yellow protein (PYP), a 14-kD soluble photoreceptor from Ectothiorhodospira halophila. Previous picosecond absorption studies from our laboratory have revealed the presence of two new early photochemical intermediates in the PYP photocycle, I(0), which appears in </=3 ps, and I(0)(double dagger), which is formed in 220 ps, as well as stimulated emission from the PYP excited state. In the present study, kinetic measurements at two excitation wavelengths (395 nm and 460 nm) on either side of the PYP absorption maximum (446 nm) were undertaken using 100-fs pump and probe pulses. Global analysis over a range of probe wavelengths yielded time constants of 1.9 ps for the photochemical formation of the I(0) intermediate via the PYP excited state, and 3.4 ps for the repopulation of the ground state from the excited state. In addition to these pathways, 395 nm excitation also initiated an alternative route for PYP excitation and photochemistry, presumably involving a different excited electronic state of the chromophore. No photochemical intermediates formed before I(0) were observed. Based on these data, a quantum yield of 0.5-0.6 for I(0) formation was determined. The structural and mechanistic aspects of these results are discussed.

Bacteria↗
PubMed1999

Fluoxetine versus amitriptyline in the treatment of major depression with associated anxiety (anxious depression): a double-blind comparison.

Although common in clinical settings, major depressive disorder with associated anxious symptoms ('anxious depression') has not been well studied in antidepressant clinical trials. The aim of this study was to compare the effects of fluoxetine versus amitriptyline in this group of patients. After a single-blind placebo run-in period of 2 weeks, patients were treated on a double-blind basis with fluoxetine or amitriptyline for 8 weeks. Assessment instruments included: 21-item Hamilton Rating Scale for Depression, Hamilton Rating Scale for Anxiety, Clinical Global Impressions, Raskin Depression Scale and Covi Anxiety Scale. A total of 157 patients were randomized to either fluoxetine or amitriptyline. Fluoxetine was given at a fixed dose of 20 mg/day and amitriptyline was given in a range of 50-250 mg/day (mean of 138.1 mg/day). Fluoxetine was comparable to amitriptyline in all efficacy measures except the HAMD sleep factor. Unwanted effects were more frequent and more severe in the amitriptyline-treated patients. Fluoxetine was comparably efficacious to amitriptyline in the treatment of major depression with associated anxiety. Since fluoxetine was far better tolerated, it is a promising alternative for this frequent and disabling condition.

Adult↗