PubMed Health⌕ Search

Biomedical subjects

J Vazquez

Publications and source records attributed to J Vazquez.

At least 55 records · Page 3Linked to original sources
PubMed1996

Innovative techniques in pediatric liver transplantation: reduced-, split- and living-donor related liver transplantation.

In spite of the increased number of organ donations, the amount of livers available for pediatric patients does not meet requirements. In an attempt to expand the pool of grafts, several techniques of size reduction (RST) have been developed: reduced-liver transplantation (RLT), liver segment transplantation (LST), "split" liver transplantation (SLT) and living-donor liver transplantation (LDLT). The aim of this work is to study the contribution of these techniques to reduction of mortality in the waiting list and the increased risks that we inflict to our patients by using these procedures. We report our experience on RST in the last nine years (23 RLT, 5 LST, 2 SLT and 3 LDLT). More than a half of them were performed in an emergency. Overall survival in children with RST (67%) is similar to that of patients receiving a "whole graft" (74%). We did not find significant differences in the incidence of graft-related complications, only reintervention for abdominal bleeding was needed more often in the RST group (30%) than in whole graft group (24%). Our data confirm the safety of the RST procedures in the pediatric liver transplantation programs and they decrease the waiting-list mortality (2.5%) among the pediatric patients.

Adolescent↗
PubMed1996

Recovery after propofol with and without intraoperative fentanyl in patients undergoing ambulatory gynecologic laparoscopy.

This prospective, randomized double-blind study was conducted to examine the effect of intraoperative opioid (fentanyl) supplementation on postoperative analgesia, emesis, and recovery in ambulatory patients receiving propofol-nitrous oxide anesthesia. Eighty patients undergoing ambulatory gynecologic laparoscopy participated. Confounding variables that could influence the incidence of postoperative emesis were controlled. Patients received either fentanyl 100 micrograms (Group I) or ketorolac 60 mg (Group II) intravenously (IV) at the time of anesthetic induction. No further analgesic supplements were given intraoperatively. Anesthesia was induced with propofol and maintained with propofol-nitrous oxide. Atracurium was used for muscle relaxation and reversed with neostigmine and glycopyrrolate. Postoperative pain during early recovery was treated with IV fentanyl 25-50 micrograms (Group I) or IV ketorolac 15-30 mg (Group II). Subsequent breakthrough pain in both groups was treated with IV fentanyl 25 micrograms increments as needed (rescue analgesia). Eighty-four percent of patients in Group I required analgesics during early recovery versus 56% of patients in Group II (P < 0.05). Maintenance dose of propofol was significantly lower in Group I (129 +/- 35 micrograms.kg-1.min-1 than in Group II (170 +/- 63 micrograms.kg-1.min-1. Immediate recovery (emergence) in the two groups was comparable, despite different propofol requirements. Although the incidence of emetic sequelae in the postanesthesia care unit was not significantly different between the two treatment groups, a significantly larger number of patients in Group I (fentanyl group) had emetic sequelae that required therapeutic intervention (Group I 29% versus Group II 10%). Patients in Group I also took a significantly longer time to ambulate and meet criteria for home discharge. These results indicate that, in patients undergoing ambulatory gynecologic laparoscopy, the practice of administering a small dose of fentanyl at the time of anesthetic induction reduces maintenance propofol requirement, but fails to provide effective postoperative analgesia. Fentanyl administration at anesthetic induction increased the need for rescue antiemetics. The relative severity of emetic sequelae could have contributed to delay in ambulation and discharge.

Adult↗
PubMed1995

Biliary atresia and the polysplenia syndrome: its impact on final outcome.

Up to 25% of babies with biliary atresia (BA) bear associated malformations that most often cluster in the polysplenia syndrome (PS). This article examines the impact of associated PS on the final outcome of the authors' BA patients and the necessary modifications of surgical technique during orthotopic liver transplantation (OLT) in these patients. The authors studied 88 consecutive infants with biliary atresia operated upon during the 10-year period between 1984 and 1993. Biliary drainage was provided by a Roux-en-Y hepaticojejunostomy. OLT was performed in 38. Eleven infants (12%) had three or more components of PS: malrotation (11), preduodenal portal vein (11), polysplenia (10), situs inversus (4), absent inferior vena cava (3), cardiac defects (2), and anomalous hepatic artery supply (2). Bile drainage was achieved in 7/11 infants (63% versus 48% for regular BA patients) 5 of whom (45% versus 31%) are jaundice-free with a mean follow-up of 105 months. Three patients received transplants (2 from living-related donor) and are alive and well with normal liver function after a mean follow-up of 35 months. Overall survival was 72% in the BA plus PS and 66% in the BA group (P = not significant [NS]). Results show that long-term bile drainage in these PS patients can be achieved at least as often as in other BA patients (45% versus 31%) (P = NS) and indicate that Kasai operation remains the best initial choice. When OLT becomes necessary, attention to vascular anatomy is required to determine the feasibility of reconstruction.(ABSTRACT TRUNCATED AT 250 WORDS)

Abnormalities, Multiple↗
PubMed1995

Our first 100 consecutive pediatric liver transplants.

Orthotopic liver transplantation (OLT) is nowadays accepted as the best therapy for end-stage liver disease. The difficulties involved are even greater in children than in adults, and it is debatable whether exclusively pediatric programs are warranted. The aim of this paper is to analyze our experience at the Children's Hospital "La Paz", with the first consecutive 100 OLT in children, 61% of whom weighed less than 20 kg. Since 1986, 220 pediatric patients were evaluated as candidates, 100 OLT were performed in 78 patients and 13 died on the waiting list, currently maintained below 15 cases. Indications were: cholestasis (45), metabolic disease (18), fulminant hepatic failure (3), primary liver tumors (2) and cirrhosis (10). Mean age was 66 months (range = 7 to 216) with a mean weight of 21 kg (range = 6 to 60), twenty patients weighed less than 13 kilograms. OLT was performed by standard technique. Reduced or segmental grafts were necessary in 8 instances. Twenty-two patients were retransplanted and 2 received three grafts. Indications for retransplantation were: hepatic artery thrombosis (8), primary nonfunction (4), chronic rejection (7), portal thrombosis (2) and Budd-Chiari recurrence (1). Acute rejection was observed in 52 patients, and eight cases developed a chronic rejection. These episodes were treated with "bolus" of steroids, monoclonal antibodies (OKT-3) and FK-506. Surgical complications included: hepatic artery thrombosis 12%, portal vein thrombosis 3% and biliary fistula or stenosis 13%. The incidence of primary non-function was 7%. Actuarial survival rate at 5 years was 75%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Biomechanical effects of different surgical procedures on the extensor mechanism of the patellofemoral joint.

Loadbearing stresses in the patellofemoral joint were studied at different degrees of flexion before and after various surgical techniques recommended to treat knee disorders. Surgical procedures intended to reduce the intensity of stress were analyzed experimentally. The study was done using different experimental methods on whole knee specimens from fresh human cadavers that were not treated with formaldehyde. The results indicate that the most predictable procedure for increasing surface area and decreasing patellar stress is a combined procedure of anterior displacement of the anterior tibial tubercle by 1 cm while displacing it 0.5 to 1 cm medially.

Biomechanical Phenomena↗
PubMed1995

Multiple cholesterol embolization syndrome: a lethal complication of vascular procedures. Report of two histologically proven cases.

Two cases of multiple cholesterol embolization syndrome (MCES) leading to death are presented. Rarely described and labeled as a "great masquerader", its presence in the medical literature is growing, since it is best diagnosed, but despite the high frequency with which MCES may occur, only a few cases are reported. This syndrome is not universally recognised.

Aged↗
PubMed1994

Sequences required for enhancer blocking activity of scs are located within two nuclease-hypersensitive regions.

The Drosophila 87A7 heat shock locus is bordered, on the proximal and distal sides, by two special chromatin structures, scs and scs'. Each structure is characterized by two sets of nuclease-hypersensitive sites, located within moderately G/C-rich DNA, flanking an A/T-rich nuclease-resistant region. scs and scs' have been shown to insulate a white reporter gene from position effects and to prevent enhancer-promoter interactions. These and other properties suggest scs and scs' might function as chromatin domain boundaries. To identify the DNA sequences which are essential for the insulating activity of scs we used an enhancer blocking assay based on the white gene. Sequences capable of suppressing activation of white by its upstream enhancer elements reside within a 900 bp DNA fragment corresponding to the scs chromatin structure. Within this region, DNA fragments associated with the two nuclease-hypersensitive regions are essential for full enhancer blocking activity, while the central A/T-rich region is dispensable. Deletions which remove part of the hypersensitive regions result in intermediate levels of white activity. Insulating activity can, however, be reconstituted by multimerizing DNA fragments from either hypersensitive region. Our results suggest that the scs boundary is assembled from a discrete number of functionally redundant DNA sequences located within both hypersensitive regions and that boundaries act by decreasing the frequency of enhancer-promoter interactions. We also show that certain types of position effects, like those involved in dosage compensation, are not efficiently blocked by scs.

ATP-Binding Cassette Transporters↗
PubMed1993

Transcriptional regulation in Drosophila during heat shock: a nuclear run-on analysis.

We used a nuclear run-on assay as a novel approach to study the changes in transcriptional activity that take place in Drosophila melanogaster during heat shock. In response to a rapid temperature upshift, total transcriptional activity in cultured KC161 cells decreased proportionally to the severity of the shock. After extended stress at 37 degrees C (15 min or more), transcription was severely reduced, and at 39 degrees C most transcription was instantaneously arrested. However, strikingly different responses were observed for individual genes. Transcription of histone H1 genes was severely inhibited even under mild heat shock conditions. Transcription of the actin 5C gene decreased progressively with increasing temperature, while transcription of the core histone genes or of the heat shock cognate genes was repressed only under severe heat shock conditions. Transcriptional activation of the D. melanogaster heat shock genes was also investigated. In unshocked cells, hsp84 was moderately transcribed, while transcriptional activity at the other protein-coding heat shock genes was undetectable (less than 0.2 polymerases per gene). Engaged but paused RNA polymerase molecules were found at the hsp70 and hsp26 genes, but not at the other heat shock genes. The rates of transcription increased with increasing temperature with a peak of expression at around 35 degrees C. At 37 degrees C, induction was less efficient, and no induction was achieved after a rapid shift to 39 degrees C. Increased transcription of the heat shock genes was observed within 1-2 min of heat shock, and maximal rates were reached within 2-5 min. Despite very similar profiles of response, different heat shock genes were transcribed at strikingly different rates, which varied over a 20-fold range. The noncoding heat shock locus 93D was transcribed at a very high rate under non-heat shock conditions, and showed a transcriptional response to elevated temperatures different from that of protein-coding heat shock genes. An estimation of the absolute rates of transcription at different temperatures was obtained.

Animals↗
PubMed1993

Vaginitis due to Saccharomyces cerevisiae: epidemiology, clinical aspects, and therapy.

Vaginitis due to Saccharomyces species is extremely rare. Nine patients with 20 vaginal isolates of Saccharomyces cerevisiae who presented with either asymptomatic vaginal colonization or symptomatic vaginitis indistinguishable from that caused by Candida albicans are described. All patients had a history of chronic or recurrent vaginitis, and all but two had systemic or local predisposing factors. In vitro tests of antimycotic sensitivity revealed reduced susceptibility of S. cerevisiae to the majority of available azole agents, with outright resistance to fluconazole. In accordance with these findings, the clinical response to conventional topical and oral antimycotic drugs was frequently suboptimal and incomplete. Electrophoretic karyotyping of strains revealed several distinct types of S. cerevisiae; this information permitted both longitudinal follow-up and differentiation of relapse from reinfection. In three patients with recurrent vaginitis, a unique epidemiological relationship was documented between S. cerevisiae and Torulopsis glabrata, another unusual and resistant vaginal pathogen. Isolation of S. cerevisiae from the vagina of symptomatic patients should not be ignored; treatment of vaginal infection with this yeast requires selected, often prolonged therapy.

Adult↗
PubMed1993

Sparfloxacin and clinafloxacin alone or in combination with gentamicin for therapy of experimental ampicillin-resistant enterococcal endocarditis in rabbits.

Sparfloxacin and clinafloxacin alone and in combination with gentamicin, were evaluated for the treatment of experimental endocarditis in rabbits caused by ampicillin-resistant enterococci. Clinafloxacin was tested against Enterococcus faecalis strain WH245, a beta-lactamase producer lacking high-level gentamicin resistance (MIC 12.5 mg/L). Sparfloxacin was tested against Enterococcus faecium strain SF2149 a non-producer of beta-lactamase (ampicillin MIC 400 mg/L, gentamicin MIC 12.5 mg/L). For strain WH245, clinafloxacin alone significantly reduced enterococcal counts in vegetations (7.7 log10 cfu/g) and for strain SF2149, sparfloxacin significantly reduced counts (7.0 log10 cfu/g) compared with untreated controls (WH245, 8.8 log10 cfu/g and SF2149, 9.3 log10 cfu) or treatment with ampicillin plus gentamicin (WH245, 9.7 log10 cfu/g). The addition of gentamicin resulted in no further reduction of bacterial counts in vegetations but resulted in an increase in sterilization of blood for strain SF2149. These results suggest that sparfloxacin and clinafloxacin and may prove useful in the therapy of infections due to ampicillin-resistant enterococci.

Ampicillin Resistance↗
PubMed1991

Response to heat shock of gene 1, a Drosophila melanogaster small heat shock gene, is developmentally regulated.

The expression of gene 1, a member of the small heat shock gene family from the Drosophila melanogaster chromosomal locus 67B was studied. In contrast to the other heat shock genes, the response of gene 1 to stress was modulated during development. In the absence of stress, gene 1 was expressed at the beginning of pupation, and at a very low level in adult males. Expression of gene 1 was substantially increased by heat shock in pupae, but was one to two orders of magnitude lower in adults or in embryos. Under the same conditions, hsp70 or hsp26 were induced to similar levels in all stages. This developmental effect could be mimicked in cultured Drosophila cells: expression of gene 1 was stimulated by heat shock in the presence, but not in the absence, of the moulting hormone ecdysterone, while the level of expression of hsp26 and hsp70 in response to heat shock was independent of the presence of the hormone. Thus, the presence and activity of the heat shock transcription factor are not sufficient for the maximal response of gene 1 to stress. These results suggest that the heat shock activator protein requires additional factors, which are developmentally regulated, to activate transcription of gene 1. Furthermore, S1 nuclease mapping analysis revealed several gene 1 mRNA species, which are generated by the use of alternative polyadenylation sites and by the use of differentially regulated transcriptional initiation sites.

Animals↗
PubMed1991

Use of toxins to study potassium channels.

Potassium channels comprise groups of diverse proteins which can be distinguished according to each member's biophysical properties. Some types of K+ channels are blocked with high affinity by specific peptidyl toxins. Three toxins, charybdotoxin, iberiotoxin, and noxiustoxin, which display a high degree of homology in their primary amino acid sequences, have been purified to homogeneity from scorpion venom. While charybdotoxin and noxiustoxin are known to inhibit more than one class of channel (i.e., several Ca(2+)-activated and voltage-dependent K+ channels), iberiotoxin appears to be a selective blocker of the high-conductance, Ca(2+)-activated K+ channel that is present in muscle and neuroendocrine tissue. A distinct class of small-conductance Ca(2+)-activated K+ channel is blocked by two other toxins, apamin and leiurotoxin-1, that share no sequence homology with each other. A family of homologous toxins, the dendrotoxins, have been purified from venom of various related species of snakes. These toxins inhibit several inactivating voltage-dependent K+ channels. Although molecular biology approaches have been employed to identify and characterize several species of voltage-gated K+ channels, toxins directed against a particular channel can still be useful in defining the physiological role of that channel in a particular tissue. In addition, for those K+ channels which are not yet successfully probed by molecular biology techniques, toxins can be used as biochemical tools with which to purify the target protein of interest.

Amino Acid Sequence↗