Search PubMed⌕ Search

Biomedical subjects

C Torres

Publications and source records attributed to C Torres.

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

[Coinfection with hepatitis G virus in chronic hepatitis C. Response to treatment with interferon alpha].

BACKGROUND: It is thought that the cytopathic effect of HGV is not important. Nevertheless, the cytopathic effect on liver is less known in the cases of co-infection with HCV. The aim was to study the prevalence of co-infection in patients with chronic hepatitis C (CHC) and to analyse the clinical-epidemiological and histological data and the interferon (IFN) response. PATIENTS AND METHODS: We included 180 patients with CHC and the HGV-RNA was determined. RESULTS: The prevalence of co-infection was 12.2% (n = 22). No statistical differences were observed between the non co-infected and co-infected groups with regard to the age, sex, mechanism of transmission and alcohol abuse. Also, there were no differences in the hepatic biochemical, no organ-specific antibodies, histological lesions and Knodell index. The HCV biochemical response (BR) and virological response (VR) after 6 months post-IFN were the same in both groups (HGV negative: BR = 29%, VR = 12%; HGV positive: BR = 22%, VR = 18%). HGV was determined after 6 months posttreatment in the co-infected group (first cycle of IFN, n = 22; second cycle of IFN, n = 9): 12 (55%) were HGV-RNA negative and 5 (23%) HCV-RNA negative, (p = 0.021). When we compared the BR vs VR in this group, there were 12 HGV-RNA negative but only two had BR (NS). On the contrary, the BR was related to HCV-RNA negative (p = 0.023). CONCLUSION: The prevalence of HGV co-infection is important in our area (12.8%). The HGV does not increase the pathogenicity of HCV and does not change the IFN response, although the HGV is more IFN sensible than HCV. The determination of HGV is not necessary in patients with HCV.

Adolescent↗
PubMed2000

Vancomycin-resistant enterococci isolated from animals and food.

One hundred and one chicken products, boiled ham and turkey cold meat were acquired from 18 different supermarkets in Spain during October 1997 to June 1998 and were analyzed for vancomycin-resistant enterococci (VRE). In the same way, 50 intestinal chicken samples from a slaughterhouse were also studied. VRE were detected in 25 of 92 samples of food of chicken origin (27.2%), but no VRE were found in cooked pork or turkey products. VRE were also detected in 8 of 50 intestinal chicken samples from the slaughterhouse (16%). VRE were identified as Enterococcus durans (n = 11), Enterococcus faecalis (n = 10), Enterococcus faecium (n = 10) and Enterococcus hirae (n = 2). All these strains were characterized as belonging to the vanA genotype by polymerase chain reaction. Ampicillin, quinupristin/dalfopristin and high level aminoglycoside resistance were frequently found among these strains. Heterogeneity was observed in susceptibility patterns among VRE strains, even in those of the same species. The high rate of colonization of chicken products by vanA containing enterococci detected 6 months to 1 year after the banning of avoparcin as a growth promoter, supports other studies suggesting that the food chain could be a source of VRE colonization in humans and thus a source of VRE infections.

Animals↗
PubMed2000

[Evaluation and validation of Omron Hem 705 CP and Hem 706/711 monitors for self-measurement of blood pressure].

OBJECTIVE: To validate two devices for self-measurement of blood pressure--The Omron Hem-705CP and the Omron Hem 706/711--according to the revised protocol of the British Hypertension Society (BHS). The results were also analysed according to the criteria for accuracy of the revised standard of the Association for the Advancement of Medical Instrumentation (AAMI). DESIGN: The British Hypertension protocol for the evaluation of blood pressure measuring devices. SETTING: Primare care. Zone III Health Care in Albacete (Spain). PARTICIPANTS: 95 subjects to validate the Omron 706/711 and 100 subjets to Omron 705. RESULTS: Two monitors surpassed the validation according to the standars set out by the BHS protocol (705 with a A grading for SBP and DBP, 706/711 obtained a B grading for SBP and an A grading for DBP and a PASS for SBP and DBP. Upon analyzing the behavior of the appliances by subgroups of BP measures (high, mid, and low), 705 for SBP > 160 mmHg obtained a B grading for the BHS protocol, but it did not pass the accuracy AAMI criteria (SD, 8.5, but difference between observers-device is -0.1 mmHg). The rest of subgroups of BP obtained a A grading for the BHS protocol and a PASS (AAMI). 706/711 surpassed in all BP subgroups BHS protocol, for DBP 80-100, SBP > 160 and DBP > 100 with a B grading, for the rest of BP subgroups obtained a B grading and a PASS (AAMI). CONCLUSIONS: On the basis of these results, we conclude both monitors Omron HEM 706/711 and the Omron 705CP surpassed the accuracy criteria required for BHS and AAMI, and can be recommended for clinical use.

Adolescent↗
PubMed2000

Impaired signal transduction in mitogen activated rat splenic lymphocytes during aging.

Mitogen activated protein kinases (MAPK) are activated by a wide variety of signals leading to cell proliferation and differentiation in different cell types. With aging, there is a marked decrease in proliferation of T-lymphocytes in response to a variety of mitogens. Several age-related changes in the activation of MAPK pathways in T-lymphocytes activated via the T-cell receptor (TCR) have been described in different species. This way, some TCR proximal defects in tyrosine kinase activity have been delineated. In this study, we have used rat splenic lymphocytes to measure the effect of aging on the activation of two MAP kinase families: ERK and JNK. In order to bypass the receptor-proximal age-dependent defects previously described, we used phorbol ester (PMA) and Ca2+ ionophore (A23187) as co-mitogens. Our results demonstrate that splenic lymphocytes from old rats have a disturbance in the activation of the ERK and JNK MAPK signal transduction pathways, that are located downstream of the receptor-proximal events. At least part of the age-related defect leading to decreased ERK activity appears to be located upstream of ERK itself, since activation of MEK is also impaired. On the other hand, the observed defects in MAPK activation do result in decreased activation of downstream events, such as c-Jun phosphorylation. Thus, we conclude that aging of splenic lymphocytes results in a functional decline in signal transduction, and at least some of these defects are located downstream of the receptor-proximal events previously described by others. The impaired activity of these two MAP kinase pathways is likely to play a role in the diminished lymphoproliferation observed in old individuals.

Aging↗
PubMed2000

Aminoglycoside-modifying enzymes in high-level streptomycin and gentamicin resistant Enterococcus spp. in Spain.

Aminoglycoside resistance was evaluated in 690 enterococcus strains isolated from different clinical sources originating from patients at the University Clinic Hospital of Zaragoza (Spain). The enterococci obtained from clinically significant samples (blood, urine, or exudates) showed more high-level resistance to gentamicin and streptomycin (65 and 42%, respectively) than those isolated from faecal samples (49 and 23%, respectively). Aminoglycoside-modifying enzymes (AME) from 119 of these high-level gentamicin and streptomycin resistant enterococcus strains were studied. The most frequent AMEs found were APH(3') and AAC(6')-APH(2"). More than one enzyme was detected in 71% of the strains (four different enzymes in 5% of the strains). Three Enterococcus faecalis strains had ANT(4')(4") enzymatic activity. Different enzymatic expressions of the bifunctional enzyme AAC(6')-APH(2") were demonstrated in strains in which the complete aac(6')-aph(2") gene was detected by PCR and hybridization: (i) AAC(6') + APH(2") activity; (ii) AAC(6') only; (iii) APH(2") only; and (iv) no activity of AAC(6') or APH(2").

Anti-Bacterial Agents↗
PubMed2000

High-level amikacin resistance in Pseudomonas aeruginosa associated with a 3'-phosphotransferase with high affinity for amikacin.

This work describes the characterization of the phosphotransferase enzymatic activity responsible for amikacin resistance in two clinical Pseudomona aeruginosa strains, isolated from a hospital that used amikacin as first-line aminoglycoside. Amikacin-resistant P. aeruginosa PA40 and PA43 (MIC: 128 mg/l) were shown to have APH activity with a substrate profile similar to that of APH(3')-VI. The enzyme from P. aeruginosa PA40 was purified to > 70% homogeneity. The Km of amikacin for this enzyme was 1.4 microM, the Vmax/Km ratio for amikacin was higher than for the other aminoglycosides tested and PCR and DNA sequencing ruled out the presence of aph(3')-IIps. Amikacin resistance in this strain was, therefore, associated with APH(3')-VI and the high affinity of this enzyme for amikacin could explain the high-level resistance that we observed.

Amikacin↗
PubMed2000

Bacteriocin production by lactic acid bacteria isolated from Rioja red wines.

Forty-two lactic acid bacteria (LAB) of the genera Lactobacillus (32), Leuconostoc (6), Pediococcus (3) and Lactococcus (1), isolated from Rioja red wines, were tested for antimicrobial activity. All these strains, as well as 18 Leuconostoc oenos and 19 yeast strains were used as indicators. Only nine strains showed antimicrobial activity, and all were of the species Lactobacillus plantarum, which constitutes the predominant microflora in Rioja red wines after alcoholic fermentation. Lact. plantarum strain J-51 showed the widest range of action, inhibiting the growth of 31 strains of the four studied LAB genera. Lact. plantarum J-51 antimicrobial activity was lost after treatment with proteases, suggesting a proteinaceous nature for this activity. It was found to be stable between pH 3 and 9 and under strong heating conditions (100 degrees C for 60 min). Polymerase chain reaction (PCR) analysis of Lact. plantarum J-51 genome revealed the presence of the plnA gene that encodes the plantaricin precursor PlnA. A 366-bp fragment was sequenced and showed 95% identity with pln locus of Lact. plantarum C-11. The deduced precursor peptide sequence showed one mutation (Gly7 to Ser7) at the double glycine leader peptide, and the three putative 26-, 23- and 22-residue active peptides remain identical to those of Lact. plantarum C-11. Therefore, antimicrobial peptides constitute a potent adaptation advantage for those strains that dominate in a medium such as wine, and can play an important role in the ecology of wine microflora.

Amino Acid Sequence↗
PubMed2000

Streptogramin resistance and shared pulsed-field gel electrophoresis patterns in vanA-containing Enterococcus faecium and Enterococcus hirae isolated from humans and animals in Spain.

The present study was performed to determine if any of the 45 vanA-containing Enterococcus faecium or 18 vanA-containing E. hirae strains were shared by chickens (32 E. faecium/l7 E. hirae) and humans (13 E. faecium/1 E. hirae) using pulsed field gel electrophoresis (PFGE) and to study quinupristin-dalfopristin (Q-D) resistance. Seven of the 45 E. faecium isolates (from 2 outpatients and from 5 poultry products) were resistant to Q-D (MIC > or = 16 microg/ml); one strain was shown to have satA by PCR and sequencing and, in the other six isolates, the recently described satG gene was demonstrated. Six different PFGE patterns were detected among the 7 Q-D E. faecium-resistant isolates. None of the E. hirae isolates showed Q-D resistance. Among the 45 vanA -containing E. faecium strains, 25 unrelated clones were found by PFGE with highly diverse patterns and an indistinguishable PFGE pattern was observed in vanA-containing E. faecium strains from two humans and two poultry products. A single PFGE pattern was detected in 17 of 18 vanA-containing E. hirae isolates, obtained from one human and 16 chicken samples. Based on the presence of indistinguishable PFGE patterns among VR E. faecium and E. hirae from humans and chickens, we conclude that horizontal transfer of these strains could occur between both groups.

Acetyltransferases↗
PubMed2000

High prevalence of erythromycin-resistant, clindamycin/miocamycin-susceptible (M phenotype) Streptococcus pyogenes: results of a Spanish multicentre study in 1998. Spanish Group for the Study of Infection in the Primary Health Care Setting.

Using the standard agar dilution method we studied the prevalence of susceptibility to 14-, 15- and 16-membered ring macrolides and clindamycin in Streptococcus pyogenes isolated in 1998 from 21 laboratories in Spain. The number of strains admitted to the study was proportional to the numbers of inhabitants in each geographical area. We also determined the susceptibility phenotypes and the genetic basis for the antibiotic resistance. A total of 486 unduplicated isolates of S. pyogenes were used. Throat swab samples provided 359 (73.9%) isolates, and the remaining 127 isolates were from other sources. One hundred and fourteen (23.5%) isolates were resistant to erythromycin, a 14-membered ring macrolide, and azithromycin, a 15-membered macrolide, whereas only 1% of isolates were resistant to miocamycin, a 16-membered macrolide and 0.8% were resistant to clindamycin. Of the 114 erythromycin-resistant strains, 109 (95.6%) were susceptible to clindamycin and miocamycin. Since induction with erythromycin did not modify susceptibility to the latter antibiotics, these 109 strains were considered to have the M phenotype. Twenty strains with the M phenotype, one per laboratory, were assayed by PCR and showed the presence of the mef gene, which is responsible for antibiotic resistance by an efflux system. Among comparable studies covering entire countries, ours demonstrates one of the highest rates of S. pyogenes erythromycin resistance and clindamycin and miocamycin susceptibility in the world. Strains with the M phenotype account for the great majority of these isolates.

Adult↗
PubMed2000

Follow-up of transmission of hepatitis C to babies of human immunodeficiency virus-negative women: the role of breast-feeding in transmission.

BACKGROUND: The studies on hepatitis C virus (HCV) vertical transmission, the effect of potential risk factors and the role of breast-feeding have reported conflicting results. PATIENTS AND METHODS: Seventy-three infants of 63 anti-HCV-positive and anti-HIV-negative mothers were studied from 1993 to 1999 in the south of Spain. The mean period of follow-up in children was 29.2 +/- 19 months (range, 8 to 76 months); 6 (8%) children were lost to follow-up. Breast milk was studied for HCV-RNA in 68 samples of 35 mothers. RESULTS: Alanine aminotransferase was high in 19 (26%) and HCV-RNA was positive in 46 (63%) pregnant woman. Breast milk HCV-RNA was negative in nonviremic mothers and positive in 20% of the viremic mothers. The overall rate of vertical HCV transmission was 11.9% (n = 8) (95% confidence interval, 6 to 23%) if HCV-RNA was positive one or more times, but only 1.5% (n = 1) (95% confidence interval, 0.1 to 9%) if HCV-RNA was permanently positive. Seven HCV-infected children did not develop antibodies to HCV, and they had a spontaneous clearance of the virus. A 10-month-old baby was HCV-RNA-positive from birth to the end of the follow-up. The genotype in each of the infants was consistent with that of their mother. The rate of HCV transmission was higher for infants of mothers with higher HCV viremia (P < 0.01) and also for infants whose mothers were HCV-RNA-positive in breast milk (P < 0.05). There were no statistically significant differences between other risk factors. CONCLUSION: The presence of transitory viremia without seroconversion indicates that the vertical transmission of HCV is not important. This could be related to the viral charge and ingestion of milk of HCV-RNA-positive mothers. However, to advise avoidance of maternal breast feeding, it would be necessary to conduct larger studies.

Adult↗
PubMed2000

Antibiotic resistance in Campylobacter strains isolated from animals, foods, and humans in Spain in 1997-1998.

Colonization by Campylobacter strains was investigated in human, broiler, and pig fecal samples from 1997-1998, as well as in foods of animal origin, and antibiotic susceptibility testing was carried out for these strains. Campylobacter strains were isolated in the foods of animal origin (55 of 101 samples; 54.4%), intestinal samples from broilers (85 of 105; 81%), and pigs (40 of 45; 88.9%). A total of 641 Campylobacter strains were isolated from 8,636 human fecal samples of clinical origin (7.4%). Campylobacter jejuni was the most frequently isolated species from broilers (81%) and humans (84%), and Campylobacter coli was most frequently isolated from pigs (100%). An extremely high frequency of ciprofloxacin resistance was detected among Campylobacter strains, particularly those isolated from broilers and pigs (99%), with a slightly lower result for humans (72%); cross-resistance with nalidixic acid was almost always observed. A higher frequency of resistance to erythromycin (81.1%), ampicillin (65.7%), gentamicin (22.2%), and amikacin (21.6%) was detected in C. coli strains isolated from pigs compared to those isolated from humans (34.5, 29.3, 8.6, and 0%, respectively). A low frequency of erythromycin resistance was found in C. jejuni or C. coli isolated from broilers. A greater resistance to ampicillin and gentamicin (47.4 and 11.9%, respectively) was detected in C. jejuni isolated from broilers than in human strains (38 and 0.4%, respectively). Beta-lactamase production was found in 81% of the Campylobacter strains tested, although 44% of them were characterized as ampicillin susceptible. The increasing rates of Campylobacter resistance make advisable a more conservative policy for the use of antibiotics in farm animals.

Animals↗
PubMed2000

Macrolide resistance genes in Enterococcus spp.

Seventy-eight isolates of different Enterococcus species (E. faecalis, n = 27; E. faecium, n = 23; E. durans, n = 8; E. avium, n = 6; E. hirae, n = 9; E. gallinarum, n = 3; and E. casseliflavus, n = 2) with a variety of erythromycin resistance phenotypes were examined for the presence of macrolide resistance genes (ermA, ermB, ermC, ermTR, mefA/E, and msrA). Positive PCR amplifications of ermB were obtained for 39 of 40 highly erythromycin-resistant Enterococcus isolates (MICs, >128 microg/ml) of different species; the remaining highly resistant E. faecium isolate was positive for PCR amplification of ermA but was negative for PCR amplification of the ermB and ermC genes. For all enterococcal strains for which erythromycin MICs were < or =32 microg/ml PCRs were negative for erm methylase genes. For all E. faecium isolates PCR amplified products of the expected size of 400 bp were obtained when msrA primers were used, with the results being independent of the erythromycin resistance phenotype. All the other enterococcal species gave negative results by msrA PCRs. Sequencing of the msrA PCR products from either erythromycin-susceptible, low-level-resistant, or highly resistant E. faecium strains showed that the amplicons did not correspond to the msrA gene described for Staphylococcus epidermidis but corresponded to a new putative efflux determinant, which showed 62% identity with the msrA gene at the DNA level and 72% similarity at the amino acid level. This new gene was named msrC.

ATP-Binding Cassette Transporters↗
PubMed2000

Upregulation of the secretory pathway in cysteine protease inhibitor-resistant Trypanosoma cruzi.

A novel chemotherapy in development for Chagas' disease targets cruzain, the major cysteine protease of Trypanosoma cruzi. Peptidomimetic inhibitors disrupt the intracellular cycle of the parasite and rescue animals from a lethal infection. Inhibitor killing of parasites results from interruption of autocatalytic cruzain processing and transport to lysosomes, and massive accumulation of precursor protein in the Golgi complex. To further understand the mechanisms of protease processing and transport in this primitive eukaryote, and uncover potential mechanisms for resistance to these drugs, we generated cysteine-protease inhibitor (CPI)-resistant epimastigotes in vitro and investigated the mechanisms involved at the biochemical and structural levels. Resistance to 20-fold the lethal CPI concentration, achieved after a year of gradual drug increase, was accompanied by a modest decrease in growth rate. A marked increase in the number of vesicles trafficking from the Golgi complex to the flagellar pocket occurs in resistant cells. No mature protease reaches lysosomes though accumulation of endocytosed gold particles in lysosomes appears to be normal. Higher molecular mass cruzain species, consistent with complexes of cruzain precursors and inhibitor, are secreted by CPI-resistant parasites into the culture supernatant. Release of these cruzain precursors may be facilitated by an enhanced acidification of trans-Golgi cisternae in resistant parasites. The pH within Golgi cisternae is higher in control epimastigotes and most mature cruzain is lysosomal. Cruzain activity is negligible in CPI-resistant epimastigote extracts compared to the parental clone. Activity is restored following withdrawal of the inhibitor. No cross-resistance to the therapeutic drugs nifurtimox and benznidazole occurred and, conversely, parasites resistant to these drugs were sensitive to CPI. Protease inhibitors are thus potential therapeutical alternatives in cases of nifurtimox/benznidazole resistance. Cumulatively, these results suggest that CPI-resistance induces upregulation of Golgi complex function and post-Golgi secretory pathway, and release of precursors before the enzyme reaches its site of biologic activity.

Animals↗
PubMed2000

Photochemical and photophysical studies of guanine derivatives: intermediates contributing to its photodestruction mechanism in aqueous solution and the participation of the electron adduct.

The low-intensity steady-state (254 nm), microsecond flash and nanosecond (266 nm) laser photolysis of some guanine (Gua) derivatives in aqueous solution were studied. A photodestruction yield between 10(-3) and 10(-2) at a base concentration of 75 microM was determined for 254 nm irradiation at room temperature using high-performance liquid chromatography. This yield decreases with increasing purine concentration. For a similar concentration of the purine bases (2 +/- 1) x 10(-5) M, the yield increases as follows: Gua approximately 9-ethylguanine < deoxyguanosine approximately guanosine (Guo) < guanosine 5'-monophosphate. At concentrations higher than 2 x 10(-4) M the Gua derivatives' photodestruction yield seems to converge to a limiting value of the order of 10(-4). This behavior is explained in terms of self-quenching and aggregation effects which deactivate the excited states of the bases. The yields of electron photoejection have been determined in the nanosecond laser photolysis (0.083) and in the low-intensity steady-state (5.8 x 10(-3)) for Guo. Competition experiments using electron scavengers suggest that the electron adducts of the bases are one of the principal species participating in the photodestruction mechanism of these monomeric Gua. Close to 75% of the total destruction yield has contributions from initial reactions of the photojected electron at neutral pH. The quantum yield of photodestruction of Guo increases when the pH is increased as follows: 4.7 x 10(-3) (pH 1.1), 6.5 x 10(-3) (pH 2.9), 7.7 x 10(-3) (pH 7.5) and 8.1 x 10(-3) (pH 11.9). This dependence on pH and the electron scavenger experiments provide further evidence for the radical anion or its protonated form as one of the principal species involved in the photodestruction of the bases at the different pH. Under oxygen saturated conditions a 22% increase in the destruction yield is observed for Guo. However, for the dinucleotides adenylyl (3'-->5')-guanosine and thymidylyl (3'-->5')2'-deoxyguanosine, the participation of the electron is 41 and 36%, respectively, suggesting that going into a more DNA or RNA-like structure, the participation of the electron adducts species in the photodamage of DNA and RNA decreases. A mechanism of photodestruction for the Gua derivatives is proposed which takes into account these findings.

Chromatography, High Pressure Liquid↗
PubMed2000

The spatial distribution of behavior under varying frequencies of temporally scheduled water delivery.

Two studies evaluated the effects of response-independent water deliveries on the location (on the floor of the experimental chamber) and position (height) of rats' behavior. In both experiments, fixed-time schedules delivered water in two dispensers that were located at opposite ends of the chamber. In Experiment 1, the two schedules provided complementary frequencies of water deliveries while the overall number of deliveries stayed constant. In Experiment 2, one of the schedules delivered water twice as frequently as the other; this proportion was kept constant while the overall density of water deliveries changed systematically. In both experiments, a single position (height) of behavior was dominant. Also, the percentage of time allocated to each dispenser was roughly proportional to the percentage of water deliveries associated with the dispensers. These data and additional considerations support the importance of examining the spatial properties and patterning of behavior.

Animals↗