Two short peptides including segments of subunit A of Escherichia coli DNA gyrase as potential probes to evaluate the antibacterial activity of quinolones

Quinolones constitute a family of compounds with a potent antibiotic activity. The enzyme DNA gyrase, responsible for the replication and transcription processes in DNA of bacteria, is involved in the mechanism of action of these drugs. In this sense, it is believed that quinolones stabilize the so-called 'cleavable complex' formed by DNA and gyrase, but the whole process is still far from being understood at the molecular level. This information is crucial in order to design new biological active products. As an approach to the problem, we have designed and synthesized low molecular weight peptide mimics of DNA gyrase. These peptides correspond to sequences of the subunit A of the enzyme from Escherichia coli, that include the quinolone resistance-determining region (positions 75-92) and a segment containing the catalytic Tyr-122 (positions 116-130). The peptide mimic of the non-mutated enzyme binds to ciprofloxin (CFX) only when DNA and Mg2+ were present (Kd = 1.6 x 10(-6) M), a result previously found with DNA gyrase. On the other hand, binding was reduced when mutations of Ser-83 to Leu-83 and Asp-87 to Asn-87 were introduced, a double change previously found in the subunit A of DNA gyrase from several CFX-resistant clinical isolates of E. coli. These results suggest that synthetic peptides designed in a similar way to that described here can be used as mimics of gyrases (topoisomerases) in order to study the binding of the quinolone to the enzyme-DNA complex as well as the mechanism of action of these antibiotics.

Enteroaggregative escherichia coli virulence factors in traveler's diarrhea strains

Enteroaggregative Escherichia coli (EAEC) is associated with diarrhea in Spanish travelers to developing countries. In this study, the polymerase chain reaction was used to test EAEC isolates for genes encoding putative virulence factors, including EAEC adhesins, the plasmid-encoded toxin (Pet), a heat-stable enterotoxin (EAST), and Shigella enterotoxins 1 and 2 (ShET1 and ShET2). Findings included a low prevalence of genes for Pet (4.3%), ShET2 (4.3%), and the adherence factor AAF/II (8.7%). The overlapping genes encoding the ShET1 and the Pic mucinase were present in most EAEC strains tested (56.5%); however, some strains that carried this locus did not produce both proteins, as determined by Western immunoblot. Surprisingly, ShET1 and ShET2 genes were also found in other E. coli pathotypes, as was the EAST toxin locus. These findings underscore the heterogeneity of EAEC strains and suggest that the ShET1 may be an important virulence factor in traveler's diarrhea.

Diarrhea in children under 5 years of age from Ifakara, Tanzania: a case-control study

A matched case-control study was conducted in the Maternal and Child Health Clinic (MCH) in Ifakara, Tanzania, during the rainy season in order to elucidate the risk factors for and etiology of diarrheal diseases in children under 5 years of age. Cases (103) and controls (206) were matched for sex and age group. Precoded questionnaires with demographic details, clinical history, and physical signs were completed. Stools samples were collected for bacterial, parasitological, and viral studies. A high number of siblings (odds ratio [OR], 0.86; P = 0.027), the number of siblings surviving (OR, 0.82; P = 0.007), the birth order (OR, 0.85; P = 0.018) and the distance from the house to the water source (OR, 0.33; P = 0.011) were associated with the risk of diarrhea. There were high rates of enteropathogen isolates in stool samples from children without diarrhea (52.23%). Shigella species were the only enteropathogen statistically related with diarrhea (OR, 2.90; P < 0.029). Enterotoxigenic, enteropathogenic, and enteroaggregative strains of Escherichia coli were not related with diarrhea, and neither were Giardia lamblia or Salmonella species.

Synchronus renal cell carcinoma and Bellini duct carcinoma: a case report on a rare coincidence

Bellini duct carcinoma or collecting duct carcinoma (CDC) is a rare but aggressive primary renal neoplasm. The coexistence of two synchronous neoplasms in the same kidney is highly infrequent. As a result, it is hardly surprising that there are no references to renal cell carcinoma (RCC) combined with CDC of the same kidney in the literature. Histology and immunohistochemistry are important tools for differentiating between the two types of tumors involved. We present the first case of a synchronous occurrence of RCC and CDC of the same kidney.

The development and validation of Spanish versions of the State and Trait Food Cravings Questionnaires

OBJECTIVE

We developed and tested the psychometric properties of Spanish versions of the Trait and State Food Cravings Questionnaires (FCQ-T and FCQ-S respectively).

METHOD

The instruments were translated and adapted to Spanish and administered to undergraduate students from a Southern university in Spain (N = 271). The data were analyzed using confirmatory factor analysis to compare the factor structure of the English and Spanish versions of both questionnaires.

RESULTS

The factors structure of both questionnaires obtained excellent fit indices across their Spanish versions with the one exception that some factors of the FCQ-S were more highly intercorrelated among the Spanish sample than the American.

DISCUSSION

This study supports the conceptualization of food cravings as universal multidimensional motivational states that can be reliably measured and supports the use of the Spanish versions of the FCQ.

[Studies of the personality of nursing students]

This study evaluates diverse psychological variables in 35 third-year nursing students. Personality is studied according to Eysenck's theories, by means of the E.P.Q. questionnaire; assertive behavior is studied by means of the Gambrill and Richey assertiveness questionnaire; and the hostility set is also measured by means of the Buss-Durkee questionnaire. Likewise, due to the results obtained, the authors point out the necessity to work on the theme of assertiveness in nursing students.

Effect of simvastatin therapy on paraoxonase activity and related lipoproteins in familial hypercholesterolemic patients

Human paraoxonase (PON1) is a calcium-dependent esterase closely associated with high density lipoprotein (HDL)-containing apolipoprotein AI (apoAI), which has been shown to confer antioxidant properties to HDL. PON1 has been recently implicated in the pathogenesis of atherosclerosis. Low PON1 activities have been found in familial hypercholesterolemia (FH) and diabetes mellitus. We have undertaken a study of the effect of the lipid-lowering drug simvastatin on serum PON1 activity (in relation to paraoxon and arylesterase activity), on apoAI-containing and apolipoprotein B (apoB)-containing lipoproteins, and on lipid peroxide concentrations in 64 (39 women and 25 men) unrelated FH patients. We have also analyzed the influence of the PON1-192 and PON1-55 genetic polymorphisms on the response of PON1 activity to simvastatin therapy. A venous blood sample for a baseline analysis and another after 4 months of simvastatin therapy at a dosage of 20 mg per day were taken. The major effect of simvastatin on lipid traits was to decrease serum cholesterol, low density lipoprotein (LDL) cholesterol, and lipid peroxide concentrations by 19.9%, 26.3%, and 37.3%, respectively. There was also a significant decrease in serum apoB, LDL apoB, and triglyceride concentrations (20.5%, 21.1%, and 15.6%, respectively). Conversely, simvastatin had no significant influence on very low density lipoprotein-lipid content, HDL cholesterol, apoAI concentrations, and lipoprotein AI and AI:AII particles. Remarkably, serum PON1 activity toward paraoxon significantly increased during treatment with simvastatin (168. 7+/-100.3 U/L before therapy versus 189.5+/-116.5 U/L after therapy, P:=0.005). Arylesterase activity displayed only a nonsignificant trend to increase after therapy. Whereas PON1 activity levels were significantly lower in FH patients before simvastatin therapy compared with those of 124 normolipidemic subjects (168.7+/-100.3 versus 207.6+/-125.2 U/L, respectively; P:<0.05), this difference disappeared after simvastatin therapy. After simvastatin therapy, a significantly negative correlation between PON1 activity and lipid peroxide concentration was observed (r=-0.35, P:=0.028). The latter also strongly correlated with LDL cholesterol concentration (r=0.64, P:<0.001). Serum PON1 activity levels were significantly lower in the low-activity PON1-192 QQ and PON1-55 M carriers than in R carriers and in LL carriers, respectively. No significant differences were found in the therapeutic response of PON1 activity between genotype groups (8.5% and 11.1% increase for QQ homozygous and R-carrier FH patients, respectively, and 12.7% and 9.5% increase for LL homozygotes and M carriers, respectively). We conclude that simvastatin may have important antioxidant properties through increasing serum PON1 activity, perhaps as a consequence of reducing oxidative stress, by a mechanism independent of apoAI-containing lipoprotein concentration and without the influence of PON1-192 and PON1-55 genetic polymorphisms. Further studies are clearly warranted to clarify the precise mechanism by which simvastatin therapy is associated with increased PON1 activity.

Combination therapy with hydroxyurea versus without hydroxyurea as first line treatment options for antiretroviral-naive patients

PURPOSE

This study analyzed whether combination therapy with hydroxyurea (HU) could be considered as first line treatment for antiretroviral-naive patients.

METHOD

The prospective open-label study was carried out from March 1996 to May 2000. The antiretroviral treatments were treatment 1-didanosine 400 mg/day, stavudine 60/80 mg/day, and HU 500 mg/day; treatment 2-two nucleosides plus a protease inhibitor; treatment 3-didanosine, indinavir, and HU (500-1,000 mg/day). The viral load (VL) and CD4 determinations were performed at weeks 24, 48, 72, and 96.

RESULTS

The sample comprised 284 patients. The distribution of patients by levels of VL and CD4 were similar in the three treatment groups. At week 24, patients receiving T1 and T3 achieved higher percentages of undetectable VL (89% and 81%, respectively) with no significant differences (p =.127) between them. The T2 group showed a lower proportion (58%) of undetectable VL, which was significantly lower than T1 (p <.0001) and T3 (p <.0007). At week 48, the results were similar to week 24. At week 96, nearly all patients had undetectable viral load (UVL). The analysis of adverse effects showed that the T2 group at week 48 had a greater proportion of adverse effects that was significantly different from T1 (p =.0026); T3 had intermediate values with no significant difference from T2 (p =.45) and from T1 (p =.048). At week 48, T1 showed higher adherence level with significant difference from the other two treatments.

CONCLUSION

Patients were followed for some 96 weeks and, with an intention-to-treat analysis, were found to do better virologically and Clinically in treatment groups containing HU. The combination of antiretroviral drugs with HU may be an excellent option as initial therapy because of its strong antiretroviral action, its lower rate of adverse effect, and the smaller cost as compared to other regimens.

[Olive oil and inhibition of low density lipoprotein oxidation. Role of phenolic compounds]

BACKGROUND

To investigate the protective effect of several olive oils with different phenolic composition on low density lipoprotein susceptibility to oxidation.

PATIENTS AND METHODS

Refined olive oil (phenolic content: 0 mg/l caffeic acid equivalents [CAE]), common olive oil (0.1 and 0.3 mg/l CAE), and virgin olive oil diluted with refined olive oil (0.1 y 0.3 mg/l CAE), were added to isolated low density lipoprotein. Conjugated dienes formation was monitored after copper-mediated low density lipoprotein oxidation.

RESULTS

An increase in the lag time of conjugated dienes formation after copper-mediated low density lipoprotein oxidation was observed linked to olive oil phenolic content (p < 0.0001, ANOVA). Multiple regression analysis showed that phenolics were the most significant antioxidants with 0.1 mg/l--increase in phenolic concentration, adjusted for alpha-tocopherol and beta-carotene, was 72 minutes (95% confidence interval [CI] 64 to 80 min) for common olive oil, and 111 min (CI 95%: 100-123 min) for virgin olive oil. In common olive oil alpha-tocopherol levels were significatively associated with the increase in the lag time (p = 0.003), reaching in virgin olive oil a borderline significant (p = 0.084).

CONCLUSIONS

Olive oil containing phenolics showed more antioxidant effect on low density lipoprotein oxidation than refined olive in relation to its phenolic content. The nature of the phenolic content influences the antioxidant capacity of an olive oil.

Protective effect of olive oil and its phenolic compounds against low density lipoprotein oxidation

The protective effect of phenolic compounds from an olive oil extract, and of olive oils with (extra-virgin) and without (refined) phenolic components, on low density lipoprotein (LDL) oxidation was investigated. When added to isolated LDL, phenolics [0.025-0.3 mg/L caffeic acid equivalents (CAE)] increased the lag time of conjugated diene formation after copper-mediated LDL oxidation in a concentration-dependent manner. Concentrations of phenolics greater than 20 mg/L inhibited formation of thiobarbituric-acid reactive substances after AAPH-initiated LDL oxidation. LDL isolated from plasma after preincubation with phenolics (25-160 mg/L CAE) showed a concentration-dependent increase in the lag time of conjugated diene formation after copper-mediated LDL oxidation. Refined olive oil (0 mg/L CAE) and extra-virgin olive oil (0.1 and 0.3 mg/L CAE) added to isolated LDL caused an increase in the lag time of conjugated diene formation after copper-mediated LDL oxidation that was related to olive oil phenolic content. Multiple regression analysis showed that phenolics were significantly associated with the increase in lag time after adjustment for effects of other antioxidants; alpha-tocopherol also achieved a statistically significant effect. These results indicate that olive oil phenolic compounds protect LDL against peroxyl radical-dependent and metal-induced oxidation in vitro and could associate with LDL after their incubation with plasma. Both types of olive oil protect LDL from oxidation. Olive oil containing phenolics, however, shows more antioxidant effect on LDL oxidation than refined olive oil.

Quinolone resistance in enterotoxigenic Escherichia coli causing diarrhea in travelers to India in comparison with other geographical areas

Enterotoxigenic Escherichia coli isolates were identified as a cause of traveler's diarrhea in 82 of 520 (16%) patients and tested for resistance to seven antimicrobial agents. Thirty patients (36%) needed antimicrobial therapy: 17 (56%) for persistence of symptoms and 13 (44%) for severity of symptoms. Ampicillin, tetracycline, and trimethoprim-sulfamethoxazole resistance was high. Chloramphenicol showed moderate activity, and amoxicillin plus clavulanic acid, nalidixic acid, and ciprofloxacin showed very good activity. Five nalidixic acid-resistant strains were isolated, four from patients visiting India.

Cognitive and emotional modulation of the cardiac defense response in humans

The cognitive and emotional modulation of the cardiac defense response was investigated in this study. One hundred forty-four participants were exposed to three presentations of an intense auditory stimulus while performing one of four attentional tasks: a control task, an external perceptual tracking task, and two internal tasks presented at either easy or difficult memory loads. State anxiety was also manipulated by requiring each group to perform either with or without the threat of shock. Heart rate and vasomotor activity were recorded. Results indicated that only the externally directed tracking task led to potentiation of the cardiac response. No predicted effects for attentional demands were obtained and the anxiety manipulation did not appear to have an effect. Differences between measures were also observed, particularly with respect to response habituation. Unlike cardiac activity, vasomotor responses displayed resistance to habituation. The results are discussed in relation to contemporary accounts of defensive responding.

In vitro selected fluoroquinolone-resistant mutants of Citrobacter freundii: analysis of the quinolone resistance acquisition

Ten quinolone-resistant mutants of Citrobacter freundii, which were selected in vitro with fluoroquinolones from two clinical isolates, were studied. The parent isolates were susceptible to quinolones in spite of showing a single substitution in the GyrB (His-417 --> Leu). No change was observed in the outer membrane proteins or in the lipopolysaccharide in any of the ten mutants studied with respect to their parent isolates. The development of quinolone resistance in selected mutants was associated with the appearance of a substitution in the GyrA (Thr-83 --> Ile) in nine of the ten mutants plus enhanced active efflux in all of them.

Decreased production of AmpC-type beta-lactamases associated with the development of resistance to quinolones in Citrobacter freundii strains

The effect of fluoroquinolones in Citrobacter freundii strains that results in a decreased expression of cephalosporin-hydrolysing beta-lactamases was studied. Resistance to broad-spectrum cephalosporins and penicillins in two C. freundii clinical isolates was associated with moderate production of chromosomal AmpC-type-beta-lactamase in addition to changes in the outer membrane proteins profile with respect to wild-type C. freundii strains. Ten quinolone-resistant mutants were derived from the two clinical isolates using increasing fluoroquinolone concentrations. The level of susceptibility to cephalosporins and meropenem of these 10 mutants was increased and was associated with a 3.6-32% diminution in the hydrolyzing activity of their periplasmic extracts containing beta-lactamases on cephaloridine as compared with those from their parent strains. Susceptibility to cephalosporins and meropenem, as well as the expression of chromosomal AmpC-type-beta-lactamase in C. freundii strains, was influenced by the exposure to quinolones.

Decreased permeability and enhanced proton-dependent active efflux in the development of resistance to quinolones in Morganella morganii

Five quinolone-resistant strains were developed from a clinical Morganella morganii isolate (M1 strain) which was susceptible to nalidixic acid and fluoroquinolones. All five in vitro selected mutants showed diminished norfloxacin accumulation and two of them also decreased the expression of the AgO in the outer membrane lipopolysaccharide with respect to their parent strain and to the M. morganii NCTC-235 type strain. Likewise, the M1 strain did not express a 37-38 kDa protein and accumulated less norfloxacin than the M. morganii NCTC-235 strain. The decreased norfloxacin uptake in the five mutants compared with the M. morganii NCTC-235 strain was due to an enhanced proton-dependent active efflux plus a pre-existent decreased expression of a 37-38 kDa protein in the parent strain.

Risk of myocardial infarction associated with Gln/Arg 192 polymorphism in the human paraoxonase gene and diabetes mellitus. The REGICOR Investigators

AIMS

There is increasing evidence that paraoxonase, an HDL-linked enzyme, exerts its effect by removing lipid-peroxidation products. We have conducted a case-control study in Gerona, Spain, to find out whether paraoxonase1 polymorphism at codon 192 (Q and R alleles) is associated with increased risk of coronary heart disease, and how diabetes mellitus, associated with high oxidative risk, influences such an association.

METHODS AND RESULTS

One hundred and fifty six consecutive myocardial infarction patients and 310 age- and sex-matched control subjects were studied. There were no differences in the distribution of genotype and allele frequencies between patients and controls. The odds ratios for diabetes and dyslipaemia in control and patients stratified by genotype group were compared. Whereas dyslipaemic status was significantly related to myocardial infarction in QQ homozygotes and R carriers, diabetes mellitus was significantly associated with myocardial infarction only in R-carrier subjects. In logistic regression analysis, diabetic R carriers demonstrated a more than two and a half-fold increase in myocardial infarction risk compared with non-diabetic R carriers (OR: 2.65, P<0.05).

CONCLUSION

These data indicate that the R allele of the paraoxonase1-192 polymorphism is not an independent risk factor for myocardial infarction in our population. However, the interaction between this polymorphism and diabetes mellitus leads to increased myocardial infarction risk in diabetic patients with the R allele.

Body image preferences of self and others: A comparison of spanish and american male and female college students

To study cross-cultural differences in various aspects of body image, we examined body size ratings of self, ideal, and ideal opposite sex, and predictions regarding the opposite sex, for men and women in two different cultures, one in which there is a high incidence of eating disorders (the United States) and one in which there is believed to be a lower incidence (Spain). Participants were 240 college students from universities in Spain or the southwest United States. A group-format version of the Body Image Assessment with both female and male silhouettes was administered to all participants. Women's ratings of current and ideal body sizes were very similar across countries, although there was a tendency for American women to be more dissatisfied with their body size. Greater differences were found for men in that, on average, American men wanted to be larger and Spanish men wanted to be smaller. Across countries, men's ratings of their ideal body size were consistent with what they predicted that women found attractive whereas women in both countries wanted to be thinner than what they predicted that men found attractive.

Resolution of high-molecular-weight components in lipopolysaccharides of Escherichia coli, Morganella morganii, Citrobacter freundii and Citrobacter diversus strains with sodium dodecyl sulfate polyacrylamide gels

The use of 0.5% sodium dodecyl sulfate in polyacrylamide separation gels allowed the resolution in several bands of high-molecular-mass components in smooth lipopolysaccharide of bacterial outer membrane from Escherichia coli, Morganella morganii, Citrobacter freundii and Citrobacter diversus. With or without 0.1% SDS, however, such a result was not possible.

Analysis of the mechanisms of quinolone resistance in clinical isolates of Citrobacter freundii

The presence of gyrA, gyrB and/or parC mutations, quinolone uptake, outer membrane protein profiles and epidemiological relationship were studied in 12 clinical isolates of Citrobacter freundii. No alterations were observed in the gyrB gene of any of the strains, or gyrA or parC of the four quinolone-susceptible strains (nalidixic acid MIC of 2-4 mg/L, and a ciprofloxacin MIC of 0.006-0.06 mg/L). The quinolone-resistant strains were classified into two groups: one group (group A) composed of strains resistant to nalidixic acid but not to ciprofloxacin and another (group B) including those resistant to both antibiotics with a mutation at codon 83 of the gyrA gene (Thr-->Ile), but no alteration in either parC or gyrB genes. In group B, three of the four resistant isolates, with a nalidixic acid MIC > 1024 mg/L and ciprofloxacin MIC of 8-32 mg/L, showed concomitant mutations at codons 83 and 87 of the gyrA gene (Thr-->Ile and Asp-->Tyr, respectively) as well as a single mutation in codon 80 of the parC gene (Ser-->Ile). The fourth isolate did not possess the mutation at codon 87 of gyrA. Two strains belong to the same clone and, although they had the same type of mutations in the gyrA and parC genes, showed different MICs of ciprofloxacin. This difference was related to an efflux pump mechanism. Mutations in the gyrA and parC genes play the main role in quinolone resistance development in Citrobacter freundii, although other factors such as overexpression of efflux pumps can play a complementary role and thus modulate the final quinolone MIC.

Mechanisms involved in the development of resistance to fluoroquinolones in Escherichia coli isolates

Eighteen quinolone-resistant isolates of Escherichia coli were selected by exposing ten clinical isolates to increasing concentrations of norfloxacin and lomefloxacin. The mutant isolates showed a multiple-antibiotic-resistance phenotype. All of them contained single mutations in gyrA consisting of the substitution of Ser-83-->Leu (n = 14), Val (n = 1) or Ala (n = 1) and the substitution of Asp-87-->Asn (n = 2). Only one concomitant mutation in parC (Ser-80-->Arg) was detected. Four parent isolates exhibited a single mutation in gyrA which required < or = 12 mg/L of norfloxacin to be inhibited. Fluoroquinolone resistance, in the 18 quinolone-resistant mutants, was a result of mutations affecting DNA gyrase plus decreased fluoroquinolone uptake. This latter mechanism of resistance was a combined effect of an absence of OmpF and an increase in active efflux in eight isolates, or an increased active efflux alone in the remaining ten selected mutants.

Antimicrobial resistance of diarrheagenic Escherichia coli isolated from children under the age of 5 years from Ifakara, Tanzania

Diarrhea caused by multidrug-resistant bacteria is an important public health problem among children in developing countries. The prevalence and antimicrobial susceptibility of diarrheagenic Escherichia coli in 346 children under 5 years of age in Ifakara, Tanzania, were studied. Thirty-eight percent of the cases of diarrhea were due to multiresistant enterotoxigenic E. coli, enteroaggregative E. coli, or enteropathogenic E. coli. Strains of all three E. coli categories showed high-level resistance to ampicillin, tetracycline, co-trimoxazole, and chloramphenicol but were highly susceptible to quinolones. Guidelines for appropriate use of antibiotics in developing countries need updating.