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A Pastor

Publications and source records attributed to A Pastor.

At least 37 records · Page 2Linked to original sources
PubMed2000

Opposite pi-face selectivity for the DMD and m-CPBA epoxidations of chiral 2,2-dimethyloxazolidine derivatives of tiglic amides: control by steric interactions versus hydrogen bonding

[formula: see text] A high extent but opposite sense in the diastereoselectivity has been observed for the DMD and m-CPBA epoxidations of the optically active tiglic amides (S)-1 with 2,2-dimethyloxazolidines as chiral auxiliaries. This unprecedented reversed pi-facial differentiation for these two peroxidic oxidants is rationalized in terms of like (lk) and unlike (ul) transition structures: For DMD, steric interactions dominate, such that the unlike transition structure is favored, while for m-CPBA, hydrogen-bonding effects overcome these steric repulsions and the like one is preferred.

Journal Article↗
PubMed2000

Novel one-step synthesis of thiazolo[3,2-b]1,2,4-triazoles.

[reaction: see text] Reactions of chalcones 3a-f with bis(1H-1,2,4-triazolyl) sulfoxide 4 formed the thiazolo[3,2-b]1,2,4-triazoles 5a-f, which resemble closely some previously prepared COX-2 inhibitors. The structure of 5a was confirmed by X-ray analysis.

Crystallography, X-Ray↗
PubMed2000

Determination of uranium in tap water by ICP-MS.

A fast and accurate procedure has been developed for the determination of uranium at microg L(-1) level in tap and mineral water. The method is based on the direct introduction of samples, without any chemical pre-treatment, into an inductively coupled plasma mass spectrometer (ICP-MS). Uranium was determined at the mass number 238 using Rh as internal standard. The method provides a limit of detection of 2 ng L(-1) and a good repeatability with relative standard deviation values (RSD) about 3% for five independent analyses of samples containing 73 microg L(-1) of uranium. Recovery percentage values found for the determination of uranium in spiked natural samples varied between 91% and 106%. Results obtained are comparable with those found by radiochemical methods for natural samples and of the same order for the certified content of a reference material, thus indicating the accuracy of the ICP-MS procedure without the need of using isotope dilution. A series of mineral and tap waters from different parts of Spain and Morocco were analysed.

Mass Spectrometry↗
PubMed2000

Complications of Chiari and Salter osteotomies: a cadaver study.

Previous investigations of the Chiari and Salter osteotomies showed that intraoperative vessel and nerve injuries are described repeatedly in the case of both pelvic osteotomies. The aim of our investigations was the exposure of each operation step in anatomic specimens to show the anatomic landmarks and potential risks. We performed nine Chiari osteotomies and five Salter osteotomies on formalin-fixed cadavers. The operation steps were made consecutively to assess the risks to the vessels and nerves as well as the determination of anatomically important reference points. In both procedures an injury of the lateral femoral cutaneous nerve at the anterior access route is feasible. By ensuring that the skin including the lateral femoral cutaneous nerve is pulled medially, injury can be avoided. Additionally, too long retraction of the tensor fasciae latae muscle injures its nutrient vessels. An inadequate subperiosteal approach during the pull on the Hohmann's retractor leads to crushing and irritation of the sciatic nerve. Moreover, there is a risk that the superior gluteal nerve as well as the superior gluteal artery may be injured. An inadequate subperiosteal application of the medial Hohmann's retractor can endanger the obturator nerve. In the Chiari osteotomy there is a risk of injury to the articular branch of the superior gluteal nerve, which supplies parts of the ventral hip joint capsule. By inserting the K-wire too far medially the internal oblique muscle is endangered. Too prolonged retraction of the iliopsoas muscle in a Salter osteotomy can lead to compression of the femoral nerve. The form of the osteotomy has an influence on the stability of the hip joint in the course of exposure of the hip joint. On account of the narrow spatial connection between the anatomic pathways and the osteotomy area, strict subperiosteal dissection and careful use of the retractor are essential to avoid nerve and vessel injuries.

Aged↗
PubMed2000

[Atrioventricular nodal reentrant tachycardia as a trigger for atrial fibrillation].

We report the case of a 43 year-old male with a long history of paroxysmal palpitations aborted by vagal manoeuvres, where atrial fibrillation was the only documented arrhythmia. During the electrophysiological study an AV nodal reentrant tachycardia was demonstrated with rapid degeneration into atrial fibrillation. After slow pathway ablation, nodal tachycardia became non-inducible. No palpitations were reported and no arrhythmic event was recorded after a follow-up of 20 months. In selected cases, the electrophysiological study could reveal potentially curable causes of atrial fibrillation.

Adult↗
PubMed2000

[Hemodynamic benefits of left ventricular pacing in two pacemakers syndromes with refractory heart failure].

We describe two cases in which right ventricular pacing produced severe hemodynamic deterioration and in which changing the pacing from the right to the left ventricle sharply corrected these alterations, while simultaneous biventricular pacing did not. Chronic left ventricular pacing can solve hemodynamic alterations in severe pacemaker syndromes, thereby avoiding the need for mitral prosthesis implantation in some cases. The use of this procedure today should be individualized, including acute hemodynamic and echocardiographic studies, because the width of the QRS complex during pacing is not a significant predictor of hemodynamic efficiency.

Aged↗
PubMed2000

How to map and ablate atrial scar macroreentrant tachycardia of the right atrium.

A special form of macroreentrant atrial tachycardia (MRAT), due to reentrant activation around surgical scars, can occur in patients after cardiac surgery. Scar MRAT occurs usually after correction of congenital defects, such as atrial or ventricular septal defects, and especially after Mustard, Senning or Fontan procedures, but it can occur also after myxoma, valvular or coronary bypass surgery. The simplest form of scar MRAT is reentry around a lateral right atrial surgical scar. A basic mapping array with multiple simultaneous recordings from the anterior and septal right atrium is very useful to make the electrophysiological diagnosis. A line of double electrograms can be mapped in the centre of the circuit and a fragmented electrogram usually marks the pivoting point between the inferior end of the scar and the inferior vena cava (IVC). Extension of the scar toward the closest fixed obstacle, usually the IVC, by means of radiofrequency ablation, can interrupt the tachycardia and make it non-inducible. Typical atrial flutter usually coexists with scar MRAT and flutter isthmus ablation is probably indicated in all cases. In patients having undergone baffle atrial surgery it can be impossible to map the whole circuit and entrainment-mapping is helpful to localize critical isthmuses in the circuit. After the Fontan operation the right atrium can be severely dilated and scarred, and multiple, complex reentry circuits can be found. Left atrial MRAT based on large areas of scar has been described, but there is still too little experience with these to propose general rules for diagnosis and management.

Catheter Ablation↗
PubMed2000

Distinct physiologic properties of microglia and blood-borne cells in rat brain slices after permanent middle cerebral artery occlusion.

The authors investigated the time course of leukocyte infiltration compared with microglial activation in adult rat brain slices after permanent middle cerebral artery occlusion (MCAO). To distinguish peripheral leukocytes from microglia, the blood cells were prelabeled in vivo with Rhodamine 6G (Rhod6G) i.v. before induction of ischemia. At specific times after infarct, invading leukocytes, microglia, and endothelial cells were labeled in situ with isolectin (IL)B4-FITC (ILB4). Six hours after MCAO only a few of the ILB4+ cells were colabeled by Rhod6G. These cells expressed the voltage-gated inwardly and outwardly rectifying K+ currents characteristic of macrophages. The majority of the ILB4+ cells were Rhod6G- and expressed a lack of voltage-gated channels, recently described for ramified microglial cells in brain slices, or exhibited only an inward rectifier current, a unique marker for cultured (but unstimulated) microglia. Forty-eight hours after MCAO, all blood-borne and the majority of Rhod6G- cells expressed outward and inward currents indicating that the intrinsic microglial population exhibited physiologic features of stimulated, cultured microglia. The ILB4+/Rhod6G- intrinsic microglial population was more abundant in the border zone of the infarct and their morphology changed from radial to ameboid. Within this zone, the authors observed rapidly migrating cells and recorded this movement by time-lapse microscopy. The current findings indicate that microglial cells acquire physiologic features of leukocytes at a later time point after MCAO.

Animals↗
PubMed2000

Pharmacokinetic interaction between amprenavir and clarithromycin in healthy male volunteers.

The P450 enzyme, CYP3A4, extensively metabolizes both amprenavir and clarithromycin. To determine if an interaction exists when these two drugs are coadministered, the pharmacokinetics of amprenavir and clarithromycin were investigated in healthy adult male volunteers. This was a Phase I, open-label, randomized, balanced, multiple-dose, three-period crossover study. Fourteen subjects received the following three regimens: amprenavir, 1,200 mg twice daily over 4 days (seven doses); clarithromycin, 500 mg twice daily over 4 days (seven doses); and the combination of the above regimens over 4 days (seven doses of each drug). Twelve subjects completed all treatments and the follow-up period. The erythromycin breath test (ERMBT) was administered at baseline, 2 h after the final dose of each of the three regimens and at the first follow-up visit. Coadministration of clarithromycin and amprenavir significantly increased the mean amprenavir AUC(ss), C(max,ss), and C(min,ss) by 18, 15, and 39%, respectively. Amprenavir had no significant effect on the AUC(ss) of clarithromycin, but the median T(max,ss)for clarithromycin increased by 2.0 h, renal clearance increased by 34%, and the AUC(ss) for 14-(R)-hydroxyclarithromycin decreased by 35% when it was given with amprenavir. Amprenavir and clarithromycin reduced the ERMBT result by 85 and 67%, respectively, and by 87% when the two drugs were coadministered. The baseline ERMBT value did not correlate with clearance of amprenavir or clarithromycin. A pharmacokinetic interaction occurs when amprenavir and clarithromycin are coadministered, but the effects are not likely to be clinically important, and coadministration does not require a dosage adjustment for either drug.

Adolescent↗
PubMed1999

[Radiofrequency ablation as the first line of treatment in patients with common atrial flutter. The arguments con].

After years of development, radiofrequency ablation of common flutter circuits is a well established procedure. Once the structure of the circuit, and its critical isthmus, were defined, effective approaches to ablation have been developed, improving initial results. The problem of recurrence has been largely controlled, and the present recurrence rate is 10-15%. The large majority of recurrences can be treated successfully by a new ablation, with a very low incidence of second recurrence. Nevertheless, isthmus ablation is not a curative procedure, because it does not address the cause of flutter, only a necessary link in the circuit. The electrophysiologic and/or anatomic abnormalities of the atrium or atria persist after ablation. Perhaps for this reason there is an incidence of atrial fibrillation in 25-30% of cases after successful flutter ablation. On the other hand, some clinical data suggest that a first episode of flutter has a low incidence of recurrence after cardioversion. For all these reasons flutter ablation should not be considered as first line treatment in all episodes of atrial flutter, but of those with recurrences and/or poor tolerance.

Atrial Flutter↗
PubMed1999

Casual recognition of an azygous continuation of the inferior vena cava in a patient with lung cancer.

Anomalous continuation of the inferior vena cava with an azygous vein is a rare vacular anomaly. The enlarged venous system may simulate adenopathies or mediastinal and retroperitoneal masses on the radiographs. We describe the case of a patient with lung cancer - a pathological condition which may cause adenopathies at these sites - and a dilated azygous-hemiazygous system resulting from failure of formation of the hepatic segment of the inferior vena cava.

Adenocarcinoma↗
PubMed1999

Pharmacokinetic interaction between ketoconazole and amprenavir after single doses in healthy men.

STUDY OBJECTIVE: To determine the effects of coadministration of amprenavir and ketoconazole on the pharmacokinetics of both drugs, and to assess the utility of the erythromycin breath test (ERMBT) to predict and explain these effects. DESIGN: Open-label, randomized, balanced, single-dose, three-period crossover study. SETTING: University research center. SUBJECTS: Twelve healthy men. INTERVENTION: Subjects received amprenavir 1200 mg, ketoconazole 400 mg, and amprenavir 1200 mg plus ketoconazole 400 mg. Each treatment was separated by 14 days. MEASUREMENTS AND MAIN RESULTS: Serial plasma samples for amprenavir and ketoconazole concentrations were measured by high-performance liquid chromatography. Coadministration of the drugs increased amprenavir area under the curve extrapolated to infinity (AUCinfinity) by 31% and reduced its maximum concentration (Cmax) by 16%. Amprenavir increased the AUCinfinity of ketoconazole by 44% and increased the drug's half-life and Cmax by 23% and 19%, respectively. Both agents resulted in substantial inhibition of ERMBT. CONCLUSION: Coadministration of ketoconazole and amprenavir results in a statistically significant increase in AUC for both agents, but the changes are not likely to be clinically important.

Adult↗
PubMed1998

Antibody response to human cytomegalovirus (HCMV) glycoprotein B (gB) in AIDS patients with HCMV end-organ disease.

Human cytomegalovirus (HCMV)-specific antibody responses in HIV-1 infected individuals either with or without HCMV end-organ disease were examined to determine the whether development of HCMV disease was associated with a particular deficit in the antibody response. Antiwhole HCMV, anti-glycoprotein B (gB), and neutralizing antibody levels were higher in HIV-1 infected individuals than in healthy immunocompetent subjects, particularly in patients with AIDS either with or without HCMV-associated disease. Irrespective of location and spread of HCMV disease, patients who had received anti-HCMV therapy prior to sampling exhibited significantly higher anti-gB and neutralizing antibody titers than those who remained untreated. Likewise, patients with HCMV disease who were antigenemic or viremic had significantly lower anti-gB and neutralizing antibody titers than those who tested negative in either assay. Patients with untreated HCMV disease had significantly lower antibody titers than AIDS patients without disease. Analysis of the IgG subclass antibody responses to gB revealed no significant differences among HIV-1 infected individuals. These results suggest that levels of detectable anti-gB and HCMV neutralizing antibodies are inversely related to systemic viral load. Thus, antibodies with such specificities may be relevant in preventing the establishment of HCMV-associated disease or in modulating its progression.

AIDS-Related Opportunistic Infections↗
PubMed1998

[The ablation of atrial flutter. The long-term results after 8 years of experience].

OBJECTIVE: Since the 1990's radiofrequency ablation radiofrequency ablation of atrial flutter has evolved in its methods and results. We have reviewed the long term outcome in 62 patients with typical (common) or reversed (clockwise) flutter undergoing radiofrequency ablation between 1990 and 1997. PATIENTS AND METHODS: Fifty men and 12 women, aged 22-78 years (57 +/- 12) with flutter recurring after cardioversion and antiarrhythmic drugs make this series. Flutter was typical in 59 cases and reversed in 3. There was no heart disease in 14, bronchopulmonary disease in 10, coronary disease in 9, cardiomyopathies in 6 and other processes in the remainder. In 5 cases with previous surgery for atrial or ventricular septal defect, Ebstein's anomaly or myxoma, we treated also a macro-reentry tachycardia around the atriotomy in the right atrium. Radiofrequency ablation was directed to the inferior vena cava-tricuspid isthmus in typical and reversed flutter, and to the isthmus between the inferior end of the atriotomy and the inferior vena cava, in the lateral right atrium, in the atriotomy tachycardias. We subdivided our patients in Group 1 (24 patients), treated until the end of 1994, and Group 2 (38 patients) treated since 1995 using specially designed catheters and trying to produce isthmus block as the endpoint of the procedure. RESULTS: Radiofrequency ablation interrupted flutter in 61 of 62 cases (98.4%), and the atriotomy tachycardia in all 5. The number of application in Group 1 was 18.6 +/- 10.1 vs 12 +/- 10 in Group 2 (p < 0.05). Follow-up was 40 +/- 24 months in Group 1 vs 16 +/- 9.5 in Group 2. Flutter recurred in 58% of Group 1 and 13% of Group 2 patients (p < 0.001), usually 1-3 months after radiofrequency ablation and they were successfully treated by new radiofrequency ablation with a small number of applications. There was no recurrence of atriotomy tachycardia. Atrial fibrillation occurred in 14 patients (23%) (11 paroxysmal, 3 persistent), with equal incidence in both groups. At the end of follow-up 85% of the patients were in sinus rhythm, although 6 needed pacemakers for sinus node dysfunction (3) or AV ablation (3). Antiarrhythmic drugs were used by 46% of patients in Group 1 and 26% in Group 2 (p = NS) for atrial arrhythmias or recurrent flutter. CONCLUSIONS: Radiofrequency ablation is an effective treatment for flutter and macro-reentry atriotomy tachycardia. Progress in methods have improved results significantly. Atrial fibrillation can still be a problem in 20-25% of the patients after flutter control.

Adult↗