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Biomedical subjects

A Segura

Publications and source records attributed to A Segura.

At least 73 records · Page 4Linked to original sources
PubMed1998

Testicular CFTR splice variants in patients with congenital absence of the vas deferens.

The involvement of the five thymidine (5T) variant in intron 8 of the cystic fibrosis membrane regulator (CFTR) gene in congenital bilateral absence of the vas deferens (CBAVD) phenotype has been extensively demonstrated. This variant leads to alternative splicing of the CFTR gene which results in a wild-type transcript and one without exon 9. Little is known about expression of the CFTR gene in the testis. We analysed the level of the aberrantly spliced transcripts in testicular biopsies and correlated it with disease expression. Quantitative RT-PCR analysis in testicular biopsies from control and CBAVD patients showed a correlation between the length of the IVS8-6(T) n tract and the level of alternatively spliced transcripts. Results from histological analysis also suggest an involvement of the alternative transcript in the spermatogenic status of patients, leading to a decreased number of mature sperm forms in the tubule.

Alternative Splicing↗
PubMed1998

Efflux pumps involved in toluene tolerance in Pseudomonas putida DOT-T1E.

The basic mechanisms underlying solvent tolerance in Pseudomonas putida DOT-T1E are efflux pumps that remove the solvent from bacterial cell membranes. The solvent-tolerant P. putida DOT-T1E grows in the presence of high concentrations (e.g., 1% [vol/vol]) of toluene and octanol. Growth of P. putida DOT-T1E cells in LB in the presence of toluene supplied via the gas phase has a clear effect on cell survival: the sudden addition of 0.3% (vol/vol) toluene to P. putida DOT-T1E pregrown with toluene in the gas phase resulted in survival of almost 100% of the initial cell number, whereas only 0.01% of cells pregrown in the absence of toluene tolerated exposure to this aromatic hydrocarbon. One class of toluene-sensitive octanol-tolerant mutant was isolated after Tn5-'phoA mutagenesis of wild-type P. putida DOT-T1E cells. The mutant, called P. putida DOT-T1E-18, was extremely sensitive to 0.3% (vol/vol) toluene added when cells were pregrown in the absence of toluene, whereas pregrowth on toluene supplied via the gas phase resulted in survival of about 0.0001% of the initial number. Solvent exclusion was tested with 1,2,4-[14C]trichlorobenzene. The levels of radiochemical accumulated in wild-type cells grown in the absence and in the presence of toluene were not significantly different. In contrast, the mutant was unable to remove 1,2,4-[14C]trichlorobenzene from the cell membranes when grown on Luria-Bertani (LB) medium but was able to remove the aromatic compound when pregrown on LB medium with toluene supplied via the gas phase. The amount of 14C-labeled substrate in whole cells increased in competition assays in which toluene-and xylenes were the unlabeled competitors, whereas this was not the case when benzene was the competitor. This finding suggests that the exclusion system works specifically with certain aromatic substrates. The mutation in P. putida DOT-T1E-18 was cloned, and the knockedout gene was sequenced and found to be homologous to the drug exclusion gene mexB, which belongs to the efflux pump family of the resistant nodulator division type.

Amino Acid Sequence↗
PubMed1998

PcaU, a transcriptional activator of genes for protocatechuate utilization in Acinetobacter.

The Acinetobacter pcaIJFBDKCHG operon encodes the six enzymes that convert protocatechuate to citric acid cycle intermediates. Directly downstream from the operon are qui and pob genes encoding sets of enzymes that convert quinate and p-hydroxybenzoate, respectively, to protocatechuate. Prior to this investigation, the only known regulatory gene in the pca-qui-pob cluster was pobR, which encodes a transcriptional activator that responds to p-hydroxybenzoate and activates transcription of pobA. The pca and qui genes were known to be expressed in response to protocatechuate, but a protein that mediated this induction had not been identified. This study was initiated by characterization of a spontaneous mutation that mapped upstream from pcaI and prevented expression of the pca genes. Sequencing of wild-type DNA extending from the translational start of pcaI through and beyond the location of the mutation revealed a 282-bp intergenic region and a divergently transcribed open reading frame, designated pcaU. Downstream from pcaU are two open reading frames encoding proteins similar in amino acid sequence to those associated with the oxidation of acyl thioesters. Inactivation of pcaU reduced the induced expression of pca structural genes by about 90% and impeded but did not completely prevent growth of the mutant cells with protocatechuate. PcaU was expressed in Escherichia coli and shown to bind to a portion of the pcaI-pcaU intergenic region containing a sequence identical in 16 of 19 nucleotide residues to a segment of the pob operator. Further similarity of the two regulatory systems is indicated by 54% amino acid sequence identity in the aligned primary structures of PobR and PcaU. The pob and pca systems were shown to differ, however, in the relative orientations of transcriptional starts with respect to the site where the activator binds to DNA, the size of the intergenic region, and the tightness of transcriptional control. The spontaneous mutation blocking pca gene expression was located in the promoter for the pca operon. The 19-nucleotide residue operator sequences were shown to be parts of a consensus associated with transcriptional activation of genes associated with protocatechuate catabolism. Two different binding sites for Pseudomonas putida PcaR differ from the consensus in only a single nucleotide residue, and DNA directly downstream from Acinetobacter pcaU contains a 19-bp segment differing from the consensus in only two residues. PcaU was shown to bind to DNA containing this segment as well as to the DNA in the pcaU-pcaI intergenic region.

Acetyl-CoA C-Acyltransferase↗
PubMed1998

The consequences of universalizing health services: children's use of health services in Catalonia.

The purpose of this study was to assess the role of needs and social factors in the use of health services among children under age 15 in Catalonia, Spain, where health care reform was explicitly designed to facilitate universal access to primary care according to health needs. Data from the Catalan Health Interview Survey of 1994, a multistage probability sample (2,433 children under 15 years old), were analyzed. Multiple regression examined the relationship between health needs and number of visits in the last year, controlling for the effect of sociodemographic characteristics. Two logistic regression equations were selected to predict heavy (more than seven visits per year) and light (less than two visits) utilization of services. The multiple regression model explained 14.3 percent of the variance in number of visits, with health status perception, disability, reported chronic condition, restriction of activities, and having had a recent accident by far the most important determinants. No familial socioeconomic characteristics, including social class, education, or family size, influenced the extent of use. In contrast to health systems not designed to achieve either universal access according to need or strong primary care, universal access to health services in Catalonia appears to enhance the use of services among children with health needs, regardless of socioeconomic characteristics.

Adolescent↗
PubMed1997

[Smoking prevalence trends in Catalonia, Spain, 1982-1994].

BACKGROUND: Smoking prevalence trends from 1982 to 1994 of adult population in Catalonia (Spain) are described. SUBJECTS AND METHODS: Four population surveys have been carried out periodically using the same questionnaires and definitions for smoking status. Surveys in 1982, 1986 and 1990 have been implemented taking samples of Catalonia population through a multistage sampling with random stratified selection by province and habitat. Individuals were chosen through a random route process. In 1994, a survey with a complex probabilistic sample design with 8 geographical areas (health regions) and 2 basic units (towns and individuals) was implemented. RESULTS: Among the 15-64 years old adults, a decrease of 6.9% in smoking prevalence has been observed. The initial prevalence in 1982 was 37.9% (CI 95%: 35.4; 40.3); in 1994 this prevalence was 35.3% (CI 95%: 34.4; 36.2). In 1994, the prevalence of current smokers in population over 14 years old was 30.6% (CI 95%: 29.8; 31.4). We have observed a significant decrease in smoking prevalence in all age groups among male population (-20.6% for the 12-year period) whereas prevalence has increased among female (+28.0%) mainly among those between 25 and 54 years old. The main percentual decrease in smoking prevalence has been observed among young people aged 15-24 years old for both genders. The proportion of former smokers has remained stable (11.4% in 1982, 12.9% in 1994) during the period studied. The proportion of former smokers increases with age among man over 25 years. CONCLUSIONS: Smoking habit is still very prevalent in Catalonia, even higher than in other Western European countries. In spite of the increase among women, the significant dectines of smoking prevalence among men and youngsters (of both genders) could represent encouraging findings in order to pursue the efforts aimed at reducing the morbi-mortality burden of smoking in our society.

Adolescent↗
PubMed1997

The effects of microabrasion on demineralization inhibition of enamel surfaces.

Microabraded enamel acquires a highly polished surface of mineralized tissue. The purpose of this study was to determine if microabraded enamel surfaces are more resistant to demineralization. Twenty extracted permanent incisors were used in the experiment. Four treatment modalities were investigated: (1) microabrasion in conjunction with a topical fluoride treatment, (2) topical fluoride treatment, (3) microabrasion, and (4) no treatment. All surfaces, following their respective treatment regimen, were stored in artificial saliva for 2 months and then exposed to an artificial caries system for 5 days. Teeth treated with microabrasion followed by a 4-minute application of 1% neutral topical sodium fluoride exhibited significantly less enamel demineralization when subjected to an artificial caries challenge than did teeth that underwent microabrasion alone, topical fluoride treatment alone, or no treatment at all.

Analysis of Variance↗
PubMed1997

An alternative approach to distalizing a maxillary molar: case report.

Using a 0.028 stainless steel wire, an appliance was fabricated to fit from the distal aspects of the laterals to the mesial side of the maxillary molars where it floats freely. Interarch Class II elastics with the potential of 16 ounces of force were used from the hooks to the lower first molar. The appliance was worn approximately 6 weeks to distalize the maxillary molar.

Child↗
PubMed1997

Enamel remineralization on teeth adjacent to Class II glass ionomer restorations.

PURPOSE: To examine the in vitro remineralization of incipient carious lesions on teeth adjacent interproximally to teeth with Class II glass ionomer cement restorations. MATERIALS AND METHODS: Artificial carious lesions were created at the contact area of 30 teeth. Ten teeth had Class II glass ionomer cement/resin composite restorations placed, 10 teeth had Class II glass ionomer silver cermet restorations placed and 10 teeth had Class II amalgam restorations placed. Sections 100 microns thick were obtained longitudinally through the caries sites and polarized photomicrographs were taken in imbibition media of water and Thoulet's (R.I. 1.41 and 1.47) solutions, representing 5%, 10% and 25% pore volume respectively. Varnish was placed on the section, leaving only the external section site exposed, then sections were situated back into the original tooth. The restored teeth were abutted to the carious tooth so that the restorations came into contact with the adjacent restoration. The specimens were placed into closed environments of artificial saliva for 14 days, then were photographed again under polarized light and areas of the carious lesions were quantitated. RESULTS: An ANOVA indicated significant variance in adjacent tooth remineralization, when comparing the experimental groups, in imbibition media of water (P < 0.05), Thoulet's 1.41 solution (P < 0.008) and Thoulet's 1.47 solution (P < 0.006). Duncan's multiple range test demonstrated the glass ionomer cement/resin composite group to have significantly greater decrease in pore volume (P < 0.05) than the amalgam control group in water imbibition media and Thoulet's 1.47 media. There was no statistically significant difference between the glass ionomer cement/resin composite and glass ionomer silver cermet groups in these two imbibition media. The glass ionomer cement/resin composite group demonstrated significantly more (P < 0.05) decrease in pore volume than both the glass ionomer silver cermet group and amalgam control group in Thoulet's 1.47 imbibition media.

Analysis of Variance↗
PubMed1997

Effect of enamel microabrasion on bacterial colonization.

PURPOSE: To determine if microabraded surfaces inhibit Streptococcus mutans colonization. MATERIALS AND METHODS: Ten extracted molars were obtained and sectioned in half mesio-distally. The mesial side was treated with microabrasion (PREMA Compound). The distal surface was designated as the control site. A plastic tube was secured on each surface with resin composite, exposing a surface of 13.2 mm 2. S. mutans 10,499 was cultured in TSB-YE supplemented with 5% sucrose and 2.5% glucose was added to each secured site in addition to 50 microliters of cell suspension. Samples were incubated in a 5% CO2 chamber for 7 days at 37 degrees C. Samples were taken from each site, incubated with dextranase (75 micrograms 1 ml), sonicated, and vortexed to disrupt cellular aggregates as much as possible. Samples were then plated on Mitis-Salivarius agar using a spiral plating system. Enumeration of numbers of colonizing bacteria was achieved following standard spiral plating system methodology. RESULTS: The mean for the microabraded group was 1.12 x 10(2) cfu/tooth and for the control it was 1.15 x 10(4). Analyzing the data revealed a significant difference (P = 0.0188).

Colony Count, Microbial↗
PubMed1996

[Diagnostic approach to neoplasms at an internal medicine service].

BACKGROUND: The aim of this study was to investigate the diagnostic behavior of different members of a department of internal medicine towards some neoplasms, analyzing the study times, reasons for suspicion and the number of tests performed and their results. PATIENTS AND METHODS: A retrospective review of the clinical histories of the patients admitted from January 1, 1992 to June 30, 1994 whose diagnosis was a new neoplasm of the digestive tract, lung cancer, cancer of unknown origin or lymphoma was carried out. The total diagnostic study time and the different partial times were measured and confirmed. The causes leading to suspicion of the neoplasms were also analyzed by groups, and finally the efficacy of the different diagnostic tests; either non invasive, oriented at the decision of the definitive test, or invasive (biopsies and fine needle aspiration puncture). RESULTS: The median total study time was 13 days with no differences between the groups. The median time until clinical suspicion was 0 days (interquartile range 0-2), being significantly greater in the digestive neoplasms. Less than half of the total study time corresponded to the clinical work itself (5 vs. 8 days). Suspicion of neoplasms in 49% of the cases arose from radiographic alteration and in 30% from clinical alterations. With regards to diagnostic tests, the value of thorax X-ray as the first exploration, mainly in the lung neoplasms (82.5% of the radiographies showed alterations), the elevated efficacy of computerized tomography, among the non invasive tests and fine needle aspiration puncture among the invasive tests were of note. Definitive diagnosis was achieved in 62% of the cases by biopsy and in 31% by fine needle aspiration puncture. CONCLUSIONS: Not all the time spent in achieving diagnosis of neoplasms is attributable to clinical work, although this may be shortened. To do so, a faster and more adequate use of the tests of greater performance (thorax X-ray, computerized tomography and fine needle aspiration puncture) should be used and performed with greater coordination and cooperation among the clinical technicians and physicians of the different departments.

Adult↗
PubMed1996

Spontaneous, persistent infection of a B-cell lymphoma with adenovirus.

An adenovirus culture-positive lymphoblastoid cell line was derived from a bone marrow transplant recipient with fatal B-cell lymphoproliferative disease and adenovirus pneumonia. At autopsy, focal areas of the lymphoma infiltrating the patient's lung were positive for adenovirus proteins by immunohistochemical staining. The Epstein-Barr virus-transformed B-cell line Mk, established from pleural fluid cells, contained adenovirus virions in both the nucleus and the cytoplasm by electron microscopy. The majority of Mk cells expressed adenovirus proteins and produced a high level of infectious adenovirus by plaque assay analysis. However, in contrast to the rapid cell death induced by adenovirus in other permissive cell lines, Mk was maintained stably in tissue culture for 6 months. These data indicate that adenoviral replication is not sufficient for cell lysis and confirm that adenovirus can cause persistent infection in human lymphoid cells in vivo.

Adenoviridae Infections↗
PubMed1996

Quantitative HIV-1 RNA as a marker of clinical stability and survival in a cohort of 302 patients with a mean CD4 cell count of 300 x 10(6)/l.

OBJECTIVE: To analyse plasma HIV-1 RNA levels as a marker of clinical stability and survival in a cohort of HIV-infected patients whose time of seroconversion is unknown. DESIGN: Retrospective cohort study. SETTING: Retrovirology laboratory and AIDS Unit in a teaching hospital. PATIENTS: A total of 916 samples from 302 patients, most on antiretroviral therapy, were analysed. Mean initial CD4 cell counts and HIV-1 RNA were 299 x 10(6)/l (range: 0-1600) and 134,261 copies/ml (range: < 200-4,300,000), respectively. Sixty-six cases had been diagnosed previously with AIDS. METHODS: Analysis of progression to AIDS and survival, according to initial and longitudinal viral load (VL) and CD4 cell count measurements was performed by Kaplan-Meier test. Relative risks were calculated by Cox's proportional hazards model. RESULTS: During a mean follow-up of 444 +/- 309 days, 29 patients developed AIDS and 21 died. Relative risk (RR) of progression related to the group with VL < 35,000 was: 10.4 when CD4 > or = 250 x 10(6)/l and VL > or = 35,000 (P = 0.001); and 45.3 when CD4 < 250 x 10(6)/l and VL > or = 35,000 (P < 0.0001). Cumulative probability of progression was: 0%, 0% and 12.3%, at the first, second and third year respectively, for patients with all their sequential VL determinations < 60,000; and 13.3%, 34.7% and 79.3% for patients who did not maintain VL values always < 60,000 (RR = 23; P < 0.0001). The minimum value of VL that reached statistical significance for the survival analysis was 100,000 copies/ml (P < 0.0001). CONCLUSIONS: VL > or = or < 35,000 is a better discriminant for progression than a CD4 cell count > or = or < 250 x 10(6)/l. Sequential VL determinations < 60,000 are associated with a better prognosis.

CD4 Lymphocyte Count↗
PubMed1996

Efficacy of triple combination therapy with zidovudine (ZDV) plus zalcitabine (ddC) plus lamivudine (3TC) versus double (ZDV+3TC) combination therapy in patients previously treated with ZDV+ddC.

OBJECTIVE: To evaluate the immunological and virological efficacy of triple combination therapy with zidovudine (ZDV) plus zalcitabine (ddC) plus lamivudine (3TC) and a double (ZDV+3TC) combination therapy in patients previously treated with ZDV plus ddC. DESIGN: A 6-month follow-up open-label randomized study was undertaken in 46 HIV-1-infected patients previously treated for at least 6 months with ZDV plus ddC, who were allocated to receive either ZDV/ddC/3TC (n = 15) or ZDV/3TC (n = 15) or to continue with the ZDV/ddC regimen (control group; n = 16). METHODS: Changes in CD4+ cell counts and plasma viral load (VL) were analysed with analysis of variance. Sequencing of the reverse transcriptase gene was performed in a subset of 3TC-treated patients. RESULTS: Mean CD4+ cell counts increased significantly above baseline in both 3TC regimens whereas counts decreased in the control group. Significant plasma VL reduction was achieved in both 3TC combination therapy groups at weeks 4 and 24 compared with the control group. Coexistence of mutations conferring resistance to ZDV and 3TC were found in patients from both 3TC treatment groups. CONCLUSIONS: Both therapy strategies, switching ddC to 3TC or adding 3TC, significantly improved the virological and immunological efficacy compared with continuing ZDV/ddC. Our results support the use of 3TC in patients previously treated with the ZDV/ddC combination.

Adult↗