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Biomedical subjects

F Navarro

Publications and source records attributed to F Navarro.

At least 55 records · Page 3Linked to original sources
PubMed2000

[Elective laparoscopic colectomy for sigmoid diverticulitis. Prospective study of 56 cases].

OBJECTIVE: The aim of this prospective study was to assess the feasibility and postoperative advantages of the laparoscopic-assisted elective colectomy for diverticular disease. PATIENTS AND METHODS: From january 1989 to december 1997, among the 114 patients electively operated on for diverticulitis, 56 patients were treated by laparoscopic approach. Evaluated parameters included: gender, age, weight, size, ASA score, operating time, duration of hospital stay, of analgesic treatment, and of postoperative ileus, morbidity and mortality rate. RESULTS: The study group consisted of 35 women and 21 men. Mean age was 59 years (34-81 years); 29 patients were ASA 1 and 27 ASA 2. Overall postoperative mortality rate was 0% and morbidity rate 16% (n = 9). There were no complications directly related to laparoscopic technique. The conversion rate was 14% (n = 8). Mean operating time was 300 min (200-600 min). Mean duration of postoperative ileus was 2.4 days. Mean duration of hospital stay was 9.4 days. CONCLUSION: This study demonstrates the feasibility of elective laparoscopic-assisted colonic resection for diverticular disease in more than 80% of cases with a postoperative morbidity and mortality rate comparable to those of conventional surgery.

Adult↗
PubMed2000

Paired inhibitory and triggering NK cell receptors for HLA class I molecules.

Human natural killer (NK) cells specifically interact with major histocompatibility complex (MHC) class I molecules employing different receptor systems, shared with subsets of alphabeta and gammadelta T lymphocytes. Killer cell immunoglobulin-like receptors (KIRs) recognize groups of human leukocyte antigen (HLA) class Ia proteins displaying common structural features at the alpha-1 domain; among them, KIR2DL4 has been proposed to specifically interact with the class Ib molecule HLA-G1. Members of a related family of immunoglobulin (Ig)-like receptors (ILT2 or LIR-1 and ILT4 or LIR-2), expressed by other leukocyte lineages, interact with a broad spectrum of class Ia molecules and HLA-G1. On the other hand, CD94/NKG2-A(-C) and NKG2D lectin-like receptors, respectively, recognize the class Ib molecules HLA-E and MICA. A recurrent finding within the different receptor families is the existence of pairs of homologous molecules that often share the same ligands but display divergent functions. Inhibitory receptors tend to exhibit an affinity for HLA molecules higher than their activating counterparts. Recruitment of SH2 domain-bearing tyrosine phosphatases (SHP) by cytoplasmic phosphorylated immunoreceptor tyrosine-based inhibition motifs (ITIMs) is a crucial event for the inhibitory signalling pathway. By contrast, triggering receptors assemble with homodimers of immune tyrosine-based activation motif (ITAM)-bearing adaptor molecules (i.e., DAP12, CD3 xi) that engage tyrosine kinases (ZAP70 and syk).

Histocompatibility Antigens Class I↗
PubMed2000

In vivo misreading by tRNA overdose.

Rpb5-H147R is an AT-GC transition replacing CAC(His) by CGC(Arg) at a conserved and critical position of ABC27 (Rpb5p), one of the five common and essential subunits shared by all three eukaryotic RNA polymerases. This mutation is viable at 25 degrees C, but has a lethal phenotype at 34 degrees C. A search for dosage-dependent suppressors identified five distinct clones that all bear a copy of the tRNA(His)GUG gene. Suppression was also observed with a small genomic insert bearing this tRNA gene and no other coding sequences, under conditions where there is a sevenfold increase in the cellular concentration of tRNA(His)GUG. Overexpressing tRNA(Arg)ICG, which normally decodes the suppressed CGC codon, counteracted suppression. Suppression is codon specific because it was abolished when replacing CGC by its synonymous codons CGA, CGU, or AGA, but was not detectably affected by several nucleotide substitutions modifying the surrounding sequence and is thus largely insensitive to the nucleotide context. It is proposed that overexpressing tRNA(His)GUG extends its decoding properties from CAC(His) to the noncognate CGC(Arg) codon through an illegitimate U x G pairing at the middle base of the anticodon. Accordingly, tRNA(His)GUG would compete with tRNA(Arg)ICG for chain elongation and generate a significant level of misreading errors under normal growth conditions.

Anticodon↗
PubMed2000

Interactions between ascorbyl free radical and coenzyme Q at the plasma membrane.

A role for coenzyme Q in the stabilization of extracellular ascorbate by intact cells has been recently recognized. The aim of this work was to study the interactions between reduced ubiquinone in the plasma membrane and the ascorbyl free radical, as an approach to understand ubiquinone-mediated ascorbate stabilization at the cell surface. K-562 cells stabilized ascorbate and decreased the steady-state levels of the semiascorbyl radical. The ability of cells to reduce ascorbyl free radical was inhibited by the quinone analogs capsaicin and chloroquine and stimulated by supplementing cells with coenzyme Q10. Purified plasma membranes also reduced ascorbyl free radical in the presence of NADH. Free-radical reduction was not observed in quinone-depleted plasma membranes, but restored after its reconstitution with coenzyme Q10. Addition of reduced coenzyme Q10 to depleted membranes allowed them to reduce the signal of the ascorbyl free radical without NADH incubation and the addition of an extra amount of purified plasma membrane quinone reductase further stimulated this activity. Reduction was abolished by treatment with the reductase inhibitor p-hydroximercuribenzoate and by blocking surface glycoconjugates with the lectin wheat germ agglutinin, which supports the participation of transmembrane electron flow. The activity showed saturation kinetics by NADH and coenzyme Q, but not by the ascorbyl free radical in the range of concentrations used. Our results support that reduction of ascorbyl free radicals at the cell surface involves coenzyme Q reduction by NADH and the membrane-mediated reduction of ascorbyl free radical.

Animals↗
PubMed2000

Electron transport controls transcription of the thioredoxin gene (trxA) in the cyanobacterium Synechocystis sp. PCC 6803.

The trxA gene encoding one of the different thioredoxins of the facultative heterotrophic cyanobacterium Synechocystis sp. PCC 6803 is transcribed as a single mRNA of 450 nucleotides. Transcript accumulation is similar in all standard growth conditions but strongly decreases after transferring cell cultures from light to darkness. In steady-state conditions, trxA transcription is reduced at high (150-500 microE m(-2) s(-1)) compared with moderate (10-50 microE m(-2) s(-1)) light intensities. The stability of the trxA transcript was similar at different light intensities, and also in darkness. Photosynthetic electron transport inhibitors, as well as glucose starvation in a mutant strain lacking photosystem II, promote a strong decline in the level of trxA transcript. Primer extension analysis suggests that trxA is transcribed from two proximal promoters containing a -10 TATA box similar to the Escherichia coli consensus promoters. Unlike the trxA mRNA, the amount of thioredoxin protein was not reduced in the dark, neither at high light intensities, indicating that thioredoxin protein is very stable. Our results indicate that the thioredoxin encoded by the trxA gene is likely to be primarily regulated at the transcriptional level, rather than at the protein level, by the electron transport generated photosynthetically or from glucose metabolism.

Base Sequence↗
PubMed2000

Hodgkin's disease: correlation between causes of death at autopsy and clinical diagnosis.

PURPOSE: The causes of mortality in Hodgkin's disease patients are insufficiently known. Autopsy study is the fundamental procedure in the investigation of these causes. The present study analyzes the autopsies performed in a series of patients diagnosed as having Hodgkin's disease, determining the cause of death in each case and comparing the premortem clinical data and the postmortem findings. PATIENTS AND METHODS: A total of 486 patients diagnosed as having Hodgkin's disease between 1967 and 1996 were assessed. Autopsy was performed in 40 of the 144 deceased patients (28%). We reviewed the pathological findings, effects of treatment, discordance between the clinical diagnosis and the outcome of autopsy, and cause of death in each case. RESULTS: The most common clinical causes of death in those patients with autopsy study were tumor progression (37%) and infections (43%) in those patients with autopsy study. The rate of discordance between the clinical and autopsy diagnoses in this study was 43%. The most frequent location of residual Hodgkin's disease was in the lymph nodes. CONCLUSIONS: Autopsy study in Hodgkin's disease confirms a high rate of discrepancy between final clinical diagnosis and postmortem lesions despite advances in diagnostic methods. Autopsy revealed causes of death directly related to the treatment, as well as some lesions directly related to patient death and secondary to treatment. Infectious processes are likely to remain undetected and their symptoms can mimic tumor progression.

Adult↗
PubMed2000

Aneurysm of the anterior leaflet of the mitral valve secondary to aortic valve endocarditis.

Aneurysm of the anterior mitral leaflet is a rare complication of infective aortic valve endocarditis, the natural evolution of which is generally its rupture, with subsequent acute and severe mitral regurgitation. Its presence cannot be recognized with transthoracic echocardiography and even in surgery. We describe a 78-year-old man with aortic valve endocarditis, in whom transesophageal echocardiography was essential for the diagnosis of this complication, its therapeutic management, and the postoperative follow-up after simple valve repair. In addition, the most appropriate surgical approach is discussed.

Aged↗
PubMed2000

The effect of BCAA supplementation upon the immune response of triathletes.

INTRODUCTION: Intense long-duration exercise could lead to immune suppression through a decrease in the circulating level of plasma glutamine. The decrease in plasma glutamine concentration as a consequence of intense long-duration exercise was reversed, in some cases, by supplementing the diet of the athletes with branched-chain amino acids (BCAA). To better address this question, we have evaluated some blood parameters (lymphocyte proliferation, the level of plasma cytokines, plasma glutamine concentration, and in vitro production of cytokines by peripheral blood lymphocytes) before and after the São Paulo International Triathlon, as well as the incidence of symptoms of infections between the groups. METHODS: Twelve elite male triathletes of mean age 25.5 +/- 3.2 yr (ranging from 21.4 to 30.1 yr), weighing 74.16 +/- 3.9 kg, swam 1.5 km, cycled 40 km, and ran 10 km (Olympic triathlon) in the São Paulo International Triathlon held in April 1997 and April 1998. In both events, six athletes received BCAA and the others, placebo. RESULTS: Athletes from the BCAA group (BG) presented the same levels of plasma glutamine, before and after the trial, whereas those from the placebo group showed a reduction of 22.8% in plasma glutamine concentration after the competition. Changes in the proliferative response of peripheral blood lymphocytes were accompanied by a reduction in IL-1 production after exercise (22.2%), which was reversed by BCAA supplementation (20.3%), without changes in IL-2 production. DISCUSSION: The data obtained show that BCAA supplementation can reverse the reduction in serum glutamine concentration observed after prolonged intense exercise such as an Olympic triathlon. The decrease in plasma glutamine concentration is paralleled by an increased incidence of symptoms of infections that results in augmented proliferative response of lymphocytes cultivated in the absence of mitogens. The prevention of the lowering of plasma glutamine concentration allows an increased response of lymphocytes to ConA and LPS, as well as an increased production of IL-1 and 2, TNF-alpha, and IFN-gamma, possibly linked to the lower incidence of symptoms of infection (33.84%) reported by the supplemented athletes.

Adult↗
PubMed2000

Antibiotic resistance trends in enteropathogenic bacteria isolated in 1985-1987 and 1995-1998 in Barcelona.

Trends in resistance to antimicrobial agents used for therapy have been evaluated with 3,797 enteropathogenic bacteria, Campylobacter, Salmonella, Shigella, and Yersinia, between 1985-1987 and 1995-1998. The greater increase in the rate of resistance was observed in Campylobacter jejuni for quinolones (from 1 to 82%) and tetracycline (from 23 to 72%) and in gastroenteric salmonellae for ampicillin (from 8 to 44%), chloramphenicol (from 1.7 to 26%), and trimethoprim-sulfamethoxazole and nalidixic acid (from less than 0.5 to 11%). Multidrug resistance was detected in several Salmonella serotypes. In the 1995-1998 period, 76% of Shigella strains were resistant to trimethoprim-sulfamethoxazole, 43% were resistant to ampicillin, and 39% were resistant to chloramphenicol. Seventy-two percent of Yersinia enterocolitica O3 strains were resistant to streptomycin, 45% were resistant to sulfonamides, 28% were resistant to trimethoprim-sulfamethoxazole, and 20% were resistant to chloramphenicol.

Campylobacter↗
PubMed2000

Cloning and sequence of the gene encoding a novel cefotaxime-hydrolyzing beta-lactamase (CTX-M-9) from Escherichia coli in Spain.

A new CTX-M-type beta-lactamase (CTX-M-9) has been cloned from a clinical cefotaxime-resistant Escherichia coli strain. Despite the close identity that exists between the CTX-M-9 and Toho-2 beta-lactamases (88%), the 35 amino acids located between residues Ala-185 and Ala-219 are totally different in both enzymes. Outside of this region there are only six amino acids substitutions between both proteins.

Amino Acid Sequence↗
PubMed2000

Escherichia coli serotype O15:K52:H1 as a uropathogenic clone.

To clarify the clinical and bacteriological correlates of urinary-tract infection (UTI) due to Escherichia coli O15:K52:H1, during a 1-year surveillance period we prospectively screened all 1, 871 significant E. coli urine isolates at the Hospital de la Santa Creu i Sant Pau, Barcelona, Spain, for this serotype and assessed the epidemiological features of community-acquired UTI due to E. coli O15:K52:H1 versus other E. coli serotypes. We also compared the 25 O15:K52:H1 UTI isolates from the present study with 22 O15:K52:H1 isolates from other, diverse geographic locales and with 23 standard control strains (8 strains from the ECOR reference collection and 15 strains of nonpathogenic O:K:H serotypes) with respect to multiple phenotypic and genotypic traits. Although E. coli O15:K52:H1 caused only 1.4% of community-acquired E. coli UTIs during the surveillance period, these UTIs were more likely to present as pyelonephritis and to occur in younger hosts, with similar risk factors, than were UTIs due to other E. coli serotypes. Irrespective of geographic origin, E. coli O15:K52:H1 strains exhibited a comparatively restricted repertoire of distinctive virulence factor profiles (typically, they were positive for papG allele II, papA allele F16, and aer and negative for sfa, afa, hly, and cnf1), biotypes, ribotypes, and amplotypes, consistent with a common clonal origin. In contrast, their antimicrobial resistance profiles were more extensive and more diverse than those of control strains. These findings indicate that E. coli O15:K52:H1 constitutes a broadly distributed and clinically significant uropathogenic clone with fluid antimicrobial resistance capabilities.

Bacteremia↗
PubMed2000

Salmonella enterica serovar virchow with CTX-M-like beta-lactamase in Spain.

Four Salmonella enterica serovar Virchow strains resistant to broad-spectrum cephalosporins were isolated from patients with gastroenteritis in 1997 and 1998 in Murcia and Barcelona, Spain. The isolates expressed a beta-lactamase with a pI of about 8 and a positive PCR when specific primers for CTX-M-9 were used. These results suggest the presence of a CTX-M-9 beta-lactamase in these strains.

Drug Resistance, Microbial↗
PubMed2000

Intravascular ultrasound assessment of iliac stent procedures.

PURPOSE: To determine whether intravascular ultrasound (IVUS) is more sensitive in identifying incomplete stent deployment or mechanical disruption compared to angiography. METHODS: Over a 9-month period, 44 patients (25 men; mean age 63 years, range 36-88) treated for common or external iliac artery stenoses with balloon angioplasty and stenting underwent IVUS interrogation following completion arteriography. RESULTS: One hundred nine stents were deployed in the 44 patients. Of these, 29 (27%) stents (in 45% of patients) were found by IVUS to be incompletely deployed or to have an associated mechanical disruption despite a normal completion arteriogram. Further treatment (repeat dilation or additional stenting) was performed in 28 cases; 1 hemodynamically insignificant dissection was not treated. Twenty-six (93%) of these interventions were successful as determined by IVUS; 2 underexpanded stents did not respond to redilation. CONCLUSIONS: Incomplete stent deployment or mechanical problems associated with stenting were common in this study, occurring in nearly half of the patients. IVUS has clinical utility in identifying incomplete deployment or mechanical problems in stents with an increased sensitivity compared to contrast angiography.

Adult↗
PubMed2000

[Treatment of common bile duct stones with laparoscopy. Retrospective multicenter study with 612 patients].

OBJECTIVE: To analyse retrospectively the results of one-stage laparoscopic treatment for common bile duct stones in 19 surgical centers in France. PATIENTS: From January 1991 to July 1996, 612 patients with choledocholithiasis underwent laparoscopic treatment. RESULTS: Overall duct clearance was obtained in 489 of the 612 patients (80%): through the cystic duct in 222 of 380 patients (58.4%), by secondary choledochotomy (after unsuccessful transcystic duct extraction) in 77 of 96 (80%), and in 190 of 232 (82 %) by primary choledochotomy. The overall duct clearance rate increased from 65% in 1991 to 84% in 1996. The use of the choledochotomy approach increased from 43% in 1991 to 69% in 1996 (P<0.01), due to a substantial increase in primary choledochotomy. In contrast, the use of the transcystic approach decreased from 57% to 31% (P<0.01). The mean time for surgery was shorter for cystic duct exploration than for primary choledochotomy (101+/-51 vs. 155+/-62 min, P<0.0001). The mean hospital stay decreased from 7.7+/-3.6 days in 1991 to 4.1+/-2 days in 1996 (P<0.001). The main biliary complications were related to biliary drainage (2,8%) and retained stones (3.1%). CONCLUSION: This study confirms that laparoscopy is a good alternative with a low complication rate, a short hospital stay, and is an effective and safe option for the management of common bile duct stones.

Adolescent↗
PubMed1999

Signaling through CD43 induces natural killer cell activation, chemokine release, and PYK-2 activation.

Natural killer (NK) cell activation is the result of a balance between positive and negative signals triggered by specific membrane receptors. We report here the activation of NK cells induced through the transmembrane glycoprotein CD43 (leukosialin, sialophorin). Engagement of CD43 by specific antibodies stimulated the secretion of the chemokines RANTES, macrophage inflammatory protein (MIP)-1alpha, and MIP-1beta, which was prevented by treatment of cells with the specific tyrosine kinase inhibitor genistein. Furthermore, signaling through CD43 increased the cytotoxic activity of NK cells and stimulated an increase in the tyrosine kinase activity in antiphosphotyrosine immune complexes of NK cell lysates. PYK-2 was identified among the tyrosine kinase proteins that become activated. Hence, PYK-2 activation was observed after 20 minutes of CD43 stimulation, reached a maximum after 45 to 60 minutes, and decreased to almost basal levels after 120 minutes of treatment. Together, these results demonstrate the role of CD43 as an activation molecule able to transduce positive activation signals in NK cells, including the regulation of chemokine synthesis, killing activity, and tyrosine kinase activation.

Antigens, CD↗
PubMed1999

Specific vascular complications of orthotopic liver transplantation with preservation of the retrohepatic vena cava: review of 1361 cases.

OBJECTIVE: The objective of this study was to describe the complications specifically related to orthotopic liver transplantation (OLT) with preservation of the inferior vena cava and to their therapeutic management. This preservation technique has considerably influenced the surgical phases of liver transplantation, increasing hepatectomy time and modifying the number of vascular anastomoses. METHODS: Our retrospective multicentric study, based on data from 1361 adult patients that had undergone orthotopic liver transplantation with preservation of the inferior vena cava in France between 1991 and 1997, analyzed the concomitant surgical complications. Type of cavo-caval anastomosis performed (piggyback, end-to-side, or side-to-side), use of a temporary portacaval anastomosis, technique-related complications, and mortality, were investigated. RESULTS: Cavo-caval anastomosis was side-to-side in 50.6% of cases (n=689), piggyback in 42.7% (n=582), and end-to-side in 6.6% (n=90). In total, 882 temporary portacaval anastomosis were carried out. Fifty-five patients presented with one or more complications related to the preservation of the inferior vena cava technique; i.e., overall morbidity was 4.1% (55/1361). Overall mortality was 0.7% (10/1361). Mortality rate for patients who presented with surgical complication was 18%. A total of 64 complications were recorded: 57 (89%) were in the perioperative or immediate postoperative period and 7 (11%) were postoperative. CONCLUSIONS: These retrospective, descriptive results show significant advantages in favor of side-to-side anastomosis in terms of vascular complications. Certain factors should be evaluated specifically at pretransplant assessment to prevent certain serious complications; principally, these are anatomic factors of the recipient (inferior vena cava included in segment I, anatomic abnormalities of the inferior vena cava) and graft size. Depending on these factors, surgeons must be able to adapt the orthotopic liver transplantation, either before or during orthotopic liver transplantation, preferring the standard technique.

Anastomosis, Surgical↗
PubMed1999

Presence of tumor DNA in plasma of breast cancer patients: clinicopathological correlations.

Using different molecular techniques, DNA has been detected in the plasma of cancer patients with various types of tumors. We undertook the present study to investigate the presence of plasma DNA, before mastectomy, in patients with breast cancer at diagnosis and to analyze the clinicopathological spectrum of this subgroup of patients with respect to patients without DNA with tumor characteristics. We studied 62 patients with breast cancer, who were selected sequentially after mastectomy and diagnosis of breast carcinomas. Genomic DNA extracted from tumor and normal tissues, normal blood cells, and plasma was used for molecular studies. Alterations in polymorphic markers selected because they had been found to show a high rate of alterations in breast cancer in previous studies (D17S855, D17S654, D16S421, TH2, D10S197, and D9S161), as well as mutations in the p53 gene and aberrant methylation at the first exon of p16INK4a, were used to identify and characterize tumor and plasma DNA. Thirteen clinicopathological parameters were analyzed in each patient. We identified 56 cases (90%) with at least one molecular event in tumor DNA, and 41 cases (66%) with a similar alteration in plasma DNA. Comparison of the clinicopathological parameters between patients with and without plasma DNA revealed significant differences in the axillary involvement, rate of invasive ductal carcinoma, high proliferative index, and the parameter comprised of lymph node metastases, histological grade II, and peritumoral vessel involvement. A high proportion of breast cancer patients exhibited plasma DNA at diagnosis similar to tumor DNA, and its presence correlated significantly with pathological parameters associated with a poor prognosis.

Breast↗