PubMed Health⌕ Search

Biomedical subjects

A Gómez

Publications and source records attributed to A Gómez.

At least 19 recordsLinked to original sources
PubMed1999

Effect of body position changes on pulmonary gas exchange in Eisenmenger's syndrome.

Preliminary studies on sleep of patients with congenital heart disease and Eisenmenger's syndrome (ES) at our institution demonstrated nocturnal worsening arterial unsaturation, which appeared to be a body position-related phenomenon. To investigate the potential effect of body position on gas exchange in ES, we carried out a prospective study of 28 patients (mean age, 34.8 +/- 11.7 yr) with established ES due to congenital heart disease. In every patient, arterial blood gases were performed during both sitting and supine positions under three different conditions: room air, while breathing 100% oxygen, and after breathing oxygen at a flow rate of 3 L/min through nasal prongs. Alveolar oxygen pressure (PaO2) for the calculation of alveolar-arterial oxygen tension differences (AaPO2) was derived from the alveolar gas equation using PaCO2 and assuming R = 1. We used paired t test, repeated-measures two-way ANOVA with Bonferroni's test, and regression analysis. From sitting to supine position on room air, there was a significant decrease in PaO2 (from 52.5 +/- 7.5 to 47.5 +/- 5.5 mm Hg; p < 0. 001) and SaO2 (from 86.7 +/- 4.6 to 83.3 +/- 4.9%; p < 0.001), both of which were corrected by nasal O2 (to 68.2 +/- 21 mm Hg and to 92 +/- 4%, respectively, p < 0.005). PaCO2 and pH remained unchanged. The magnitude of the change in PaO2 correlated with the change in AaPO2 on room air (r = 0.77; p < 0.01) but not with the change in AaPO2 on 100% oxygen. It is concluded that in adult patients with ES there is a significant decrease in PaO2 and SaO2 when they change from the sitting to the supine position. A ventilation-perfusion (V/Q) distribution abnormality and/or a diffusion limitation phenomenon rather than an increase in true shunt may be the mechanisms responsible for this finding. The response to nasal O 2 we observed warrants a trial with long-term nocturnal oxygen therapy in these patients.

Adult↗
PubMed1998

Analysis of Ecteinascidin 743, a new potent marine-derived anticancer drug, in human plasma by high-performance liquid chromatography in combination with solid-phase extraction.

A reversed-phase high-performance liquid chromatographic method has been developed and validated for the quantification of the novel anticancer drug Ecteinascidin 743 in human plasma. The sample pretreatment of the plasma samples involved a solid-phase extraction (SPE) on cyano columns. Propyl-p-hydroxybenzoate was added after the sample pretreatment to correct for variability in injection volumes. The separation was performed on a Zorbax SB-C18 column (75x4.6 mm I.D., particle size 3.5 microm) with acetonitrile-25 mM phosphate buffer, pH 5.0 (70:30, v/v) as the mobile phase. The flow-rate was 1.0 ml/min and the eluent was monitored at 210 nm. The accuracies and precisions of the assay fall within +/-15% for all quality control samples and within +/-20% for the lower limit of quantitation, which was 1.0 ng/ml using 500 microl of plasma. The overall recovery of the sample pretreatment procedure for Ecteinascidin 743 was 87.0+/-5.9%. The drug was found to be stable in human plasma at -30 degrees C for at least 2 months. At room temperature Ecteinascidin 743 was stable in human plasma for 5 h at most.

Animals↗
PubMed1998

Signalling by the oncogenic receptor tyrosine kinase Xmrk leads to activation of STAT5 in Xiphophorus melanoma.

Overexpression of the mutationally activated Xmrk receptor initiates the formation of hereditary malignant melanoma in the fish Xiphophorus. In addition to transcriptional overexpression a cell-type specific signal transduction is essential for Xmrk mediated tumor formation. To elucidate the consequence of Xmrk signalling and to identify target proteins that characterize the tumor phenotype, we analysed proteins that are strongly tyrosine phosphorylated in the fish melanoma cell line PSM. One of the most prominent phosphotyrosine proteins was found to be the signal transducer and activator of transcription STAT5. In a heterologous cell system (murine pro B-cells), activation of the Xmrk kinase in a chimeric receptor induced tyrosine phosphorylation, nuclear translocation and DNA binding of STAT5. Following receptor stimulation, expression of the STAT5 specific target genes cis, osm and pim-1 was induced. In Xiphophorus PSM cells STAT5 was found to be preferentially localized in the nucleus, but treatment with tyrphostin AG555, a specific Xmrk kinase-inhibitor, blocked nuclear localization. In these cells as well as in Xiphophorus melanoma expression of pim-1 and constitutive DNA-binding activity of STAT5 was detectable. This constitutive activity was higher in malignant than in benign melanomas, indicating that STAT5 activation is correlated with the malignancy of these tumors.

Animals↗
PubMed1998

Activation of the Xmrk proto-oncogene of Xiphophorus by overexpression and mutational alterations.

Xmrk is a receptor tyrosine kinase closely related to the human EGF receptor. In the teleost fish Xiphophorus two versions of the Xmrk gene exist, an oncogene (ONC) and a proto-oncogene (INV). While ONC-Xmrk is the melanoma-inducing gene, INV-Xmrk appears not to be involved in transformation of pigment cells. To elucidate the mechanism that converts the proto-oncogene into a transforming oncogene a comparative analysis of the structure, expression and function of both versions of the gene was performed. In contrast to ONC-Xmrk which is expressed at high levels in melanoma cells, the proto-oncogene INV-Xmrk is ubiquitously expressed at very low levels indicating overexpression as one possible reason for tumorigenicity by ONC-Xmrk. As sequence comparison of the proto-oncogene and the oncogene revealed a number of amino acid changes, a possible effect of these mutations on the activation of the ONC-Xmrk receptor was determined. A constitutive activation of the oncogenic receptor was found and ectopic expression of INV-Xmrk after microinjection into medakafish embryos did not lead to the high tumour rate in transgenic fish as observed for the oncogene. Our data therefore suggest that overexpression of the receptor alone is not sufficient for melanoma induction, but that in addition activating mutations in ONC-Xmrk are responsible for its full tumorigenic potential.

Amino Acid Sequence↗
PubMed1998

A physical optics approach to kinematical diffraction.

In this work the physical optics approach (Fourier Optics) that has been so successful in formulating the (multislice) high energy theory of electron diffraction is used to formulate the kinematical theory of electron diffraction. The resulting expressions already have the required phase factors and Ewald's sphere built in. A simple link to the weak phase object approximation and to the multislice theory is provided.

Kinetics↗
PubMed1998

Quantitative determination of Ecteinascidin 743 in human plasma by miniaturized high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry.

A method was developed for the bio-analysis of Ecteinascidin 743 (ET-743) using miniaturized liquid chromatography (LC) coupled to an electrospray ionization sample inlet (TurbolonSpray) and two quadrupole mass analyzers (LC/ESI-MS/MS). Solid-phase extraction was used as a sample pretreatment procedure. Ecteinascidin 743 is a very potent anticancer compound and is administered in microgram m-2 dosages, which demands special requirements in terms of sensitivity for the analytical method supporting clinical pharmacokinetic studies. Using conventional LC/UV, a lower limit of quantitation (LLQ) of 1 ng ml-1 plasma was reached using a 500 microliters sample volume, but LC/ESI-MS/MS permitted an LLQ of 10 pg ml-1. The latter method was found to be accurate and precise, and provided a broad linear concentration range of 0.010-2.50 ng ml-1.

Antineoplastic Agents↗
PubMed1998

[Iatrogenic vascular lesions after cardiac catheterization].

INTRODUCTION AND PURPOSE: The increase in vascular complications after cardiac catheterizations is rising due to the increase in the total number of these procedures. The purpose of this report is to determine the incidence of this complication and to identify the variables which are related to the presence of vascular complications which required surgical repair. MATERIAL AND METHODS: Retrospective review of the 3,723 cardiac catheterizations made by the interventional cardiology department during a period between June 1992 to August 1996. RESULTS: Thirty two vascular complications were detected (0.9%), which required surgical reparation. There was no statistical difference in age, sex, presence of vascular risk factors, cardiac indication for catheterization and vascular approach between those patients who had a vascular complication and those who did not. The presence of obesity [RR: 2.5, IC 95% (1.2-5)], use of catheter sheath, superior or equal to 8F [RR: 0.3, IC 95% (0.14-0.62)] and use of systemic anticoagulation [RR: 4.8, IC 95% (2.1-10.8)], increase the risk of vascular complications. Two patients died (6.2%) due to cardiac complications and there were minor complications in 23% after surgical repair. CONCLUSION: Vascular complications after cardiac catheterization continue to be a significant problem. There are several variables which influence the presentation of vascular complications. Continued surveillance of cardiac catheterization complications is necessary to minimize problems and improve results.

Adult↗
PubMed1998

Graded balloon dilation atrial septostomy in severe primary pulmonary hypertension. A therapeutic alternative for patients nonresponsive to vasodilator treatment.

OBJECTIVES: We sought to investigate the acute hemodynamic effects of graded balloon dilation atrial septostomy (BDAS) and to define the long-term impact of this procedure on New York Heart Association functional class and survival in adult patients with primary pulmonary hypertension (PPH). BACKGROUND: Current treatment strategies for patients with severe and refractory PPH are limited by either technical difficulties and high mortality or cost. METHODS: We studied 15 patients with severe PPH. BDAS was successfully performed in all patients by crossing the interatrial septum with a Brockenbrough needle, followed by progressive dilation of the orifice with a Mansfield balloon in a hemodynamically controlled, step-by-step manner. RESULTS: BDAS caused an immediate significant fall in right ventricular end-diastolic pressure and in systemic arterial oxygen saturation and an increase in cardiac index. One patient died, and 14 survived the procedure and significantly improved their mean functional class (from 3.57 +/- 0.6 to 2.07 +/- 0.3 [mean +/- SD], p < 0.001). Exercise endurance (6-min test) also improved from 107 +/- 127 to 217 +/- 108 m (p < 0.001). Because of spontaneous closure, BDAS was repeated in four patients. The survival rate among patients who survived the procedure was 92% at 1, 2 and 3 years, which is better than that for historical control PPH patients (73%, 59% and 52%, respectively). CONCLUSIONS: With careful monitoring, BDAS is a safe and useful palliative treatment for selected patients with severe PPH.

Adult↗
PubMed1998

[Acute hepatocellular lesion induced by amoxicillin-clavulanic acid].

Since first description in 1988, numerous cases of amoxycillin-clavulanic acid hepatotoxicity have been reported. Most of them are cholestatic hepatitis. A case of acute hepatocellular injury by amoxycillin-clavulanic acid is reported in a 23-years-old male, with a favourable outcome after 18 weeks.

Acute Disease↗
PubMed1998

[Pancreatic abscess caused by Candida following wide-spectrum antibiotic treatment].

Pancreatic infection by Candida is an infrequent entity. We report two cases and review literature. A 67 year-old woman who was admitted for severe acute pancreatitis of biliary origin developed high fever during fourth week of stay; it was secondary to a pancreatic abscess due to Candida. On the other hand, a 67 year-old man with severe acute biliary pancreatitis and renal insufficiency showed an abscess of similar characteristics that was identified during fourth week of evolution. Both of them recovered completely after surgical drainage and antifungical parenteral treatment. The use of broad spectrum antibiotics recently recommended for prophylaxis of pancreatic infection in patients with necrotizing acute pancreatitis, can favour opportunistic infection by several agents. Pancreatic abscesses by Candida often occurs in patients receiving broad spectrum antibiotics, although it isn't an essential condition. The fact that Candida could be only a contaminant may delay diagnosis and early treatment, and then it can determine a poor outcome. Adequate treatment is urgent surgical drainage associated with antifungical parenteral therapy. Usefulness of antifungic drugs in patients undergoing long term antibiotic prophylaxis for secondary infection must be evaluated.

Abscess↗
PubMed1998

[Chronic elevation of enzymes of pancreatic origin in asymptomatic patients].

Chronic asymptomatic elevation of pancreatic enzymes is a well known entity although little has been reported. In most cases chronic asymptomatic elevation of amylase is due to a salival isoamylase increase or macroamylasemia. However, we have studied 10 cases with an increase in amylases due to pancreatic isoamylase and an increase in the remaining pancreatic enzymes which remained elevated during the follow up period ranging from 2 to 60 months. The amylase values ranged from 186 to 1,600; the lipase from 176 to 3,989, trypsin from 476 to 2,430 and pancreatic isoamylase from 122 to 1,263. In all patients CT and echography were carried out, which discarded structural damage. Nonetheless, an indirect test of pancreatic function presented unexplained pathologic values in 4 out of 10 patients. In conclusion, we suggest that chronic asymptomatic elevation of pancreatic enzymes is of unknown etiology with no associated structural pancreatic pathology demonstrable by the usual study methods.

Adult↗