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M J López

Publications and source records attributed to M J López.

At least 19 recordsLinked to original sources
PubMed2006

Effect of inoculation in composting processes: modifications in lignocellulosic fraction.

Three microbial isolates, identified as Bacillus shackletonni, Streptomyces thermovulgaris and Ureibacillus thermosphaericus were tested as inoculants in composting processes in relation to their capacity to improve lignocellulose degradation. Different wastes from agricultural activities were used as raw material for the heaps: pepper plant waste (PPW) as the main component and olive-oil mill waste (OMW), almond shell (AS), pruning waste (PW) and rice straw (RS) as additives. Cellulose was more extensively degraded than hemicellulose and lignin, although the use of inoculants (B. shackletonni and S. thermovulgaris) improved the action of the autochthonous microbiota just in the AS heaps. A higher efficiency was observed for lignin, since lower concentrations of this polymer were detected in the inoculated heaps in relation to control heaps. U. thermosphaericus was the most efficient microorganism since inoculation with this strain decreased the final lignin content in a range between 17.23% and 24.34%. S. thermovulgaris and B. shackletonni led to a higher reduction of the lignin levels in the OMW and PW heaps (14.25% and 19.07% less lignin than control heaps) and OMW (13%), respectively. The composting process can therefore be improved by means of inoculation if the microorganisms used for this purpose are appropriate for the characteristics of the raw material.

Agriculture↗
PubMed2006

Effect of horticultural waste composting on infected plant residues with pathogenic bacteria and fungi: integrated and localized sanitation.

The aim of this work was to study the effect of composting on the viability of plant pathogenic fungi and bacteria. The research consisted of pilot-scale composting of horticultural waste in compost windrows. Studies were carried out on vegetable residues infected with plant pathogenic microorganisms included by either integrated or localized infection. In the first case, the plant pathogen viability was investigated when infected material was mixed throughout compost, while the localized infection was used to study the effect of the composting process on plant waste spot-inoculated with pathogenic microorganisms. Results for localized sanitation showed the total elimination of all tested phytopathogens between 48 and 120 h after composting began. In this case significant differences were observed in relation to 9 different zones in the pile. The disappearance of these microorganisms was similar when all plant waste included in the windrow was infected (integrated infection). Additionally, the results obtained confirmed that the bacteria showed a greater capacity to persist during composting than the fungi. Composting is therefore considered a useful method for recycling horticultural waste and eliminating phytopathogenic bacteria and fungi that inhabit this kind of residue.

Agriculture↗
PubMed2005

Enhancement of hydrogen physisorption on graphene and carbon nanotubes by Li doping.

Density-functional calculations of the adsorption of molecular hydrogen on a planar graphene layer and on the external surface of a (4,4) carbon nanotube, undoped and doped with lithium, have been carried out. Hydrogen molecules are physisorbed on pure graphene and on the nanotube with binding energies about 80-90 meV/molecule. However, the binding energies increase to 160-180 meV/molecule for many adsorption configurations of the molecule near a Li atom in the doped systems. A charge-density analysis shows that the origin of the increase in binding energy is the electronic charge transfer from the Li atom to graphene and the nanotube. The results support and explain qualitatively the enhancement of the hydrogen storage capacity observed in some experiments of hydrogen adsorption on carbon nanotubes doped with alkali atoms.

Journal Article↗
PubMed2005

Simulating the thermal behavior and fragmentation mechanisms of exohedral and substitutional silicon-doped C60.

Structures, thermal behavior, and fragmentation mechanisms of exohedral and substitutional silicon-doped C(60) containing 1-12 Si atoms are investigated by extensive molecular-dynamics simulations. A nonorthogonal tight-binding model is used to mimic the interatomic interactions in the doped fullerenes. Beginning from the minimum-energy structures, the temperature of the doped fullerenes is slowly increased until fragmentation takes place. A correlation can be established between the exohedral and substitutional structures and the corresponding fragmentation mechanisms and fragmentation temperatures. Exohedral C(60)Si(m) fullerenes fragment into two homonuclear pieces, the Si(m) cluster and the C(60) fullerene that remains intact. In contrast, the substitutional C(60-m)Si(m) heterofullerenes undergo structural transformations, including the partial unraveling of the cage, prior to fragmentation. Then, ejection of atoms or small molecules takes place from the distorted structures. The slow heating rate used, combined with long simulation runs, allows us to determine the fragmentation temperature of exohedral and substitutional Si-doped fullerenes as a function of the number of silicon atoms. Substitutional Si-doped fullerenes exhibit much higher fragmentation temperatures (1000-1500 K higher) than the exohedral fullerenes. This can be understood from the different bonding of the Si atoms in both structures.

Journal Article↗
PubMed2005

Determinants of health system delay among confirmed tuberculosis cases in Spain.

BACKGROUND: Health system delay (HSD) is an important issue in tuberculosis (TB) control. This report investigates HSD and associated factors in a cohort of Spanish culture-confirmed TB patients. METHODS: Data were collected from clinical records. Using logistic regression with two different cut-off points to define HSD (median and 75th percentile), adjusted odds ratios were used to estimate the association between HSD and different variables. RESULTS: A total of 5184 culture-confirmed TB cases were included. Median and 75th percentile HSD were 6 and 25 days respectively. HSD significantly greater than the median was associated with: age >44 years, past or present intravenous drug use, diagnosis at a primary-care centre, prior preventive therapy, positive histology, request for drug-sensitivity testing, presence of silicosis or neoplasia in addition to TB, presence of non-TB related symptoms, and gastrointestinal site. HSD greater than the 75th percentile was related to the same variables, with the exception of diagnosis at a primary-care centre, positive histology, silicosis, non-TB-related symptoms and gastrointestinal site, for which the association disappeared; in contrast, an association with female gender emerged. CONCLUSION: Despite free health care being universally available in Spain, there are some groups of TB patients whose treatment is unduly delayed.

Adolescent↗
PubMed2005

Accuracy of blood culture for early diagnosis of mediastinitis in febrile patients after cardiac surgery.

Postsurgical mediastinitis (PSM) remains a major cause of morbidity and mortality in patients undergoing cardiac surgery procedures. Although prompt diagnosis is crucial in these patients, neither clinical data nor imaging techniques have shown enough sensitivity or specificity for early diagnosis of PSM. The aim of the present study was to assess the validity of blood cultures as a diagnostic test for the early detection of PSM in patients who become febrile after cardiac surgery procedures. During a 4-year period (1999-2002), patients who developed fever (>37.8 degrees C) in the first 60 days after a cardiac surgery procedure were evaluated. Blood cultures were drawn from these patients. PSM was defined as deep infection involving retrosternal tissue and/or the sternal bone directly observed by the surgeon and confirmed microbiologically. Three criteria for positivity of blood cultures were applied: bacteremia, staphylococcal bacteremia, or Staphylococcus aureus bacteremia. For purposes of the analysis, a positive blood culture in patients with PSM was considered a true-positive test and a negative blood culture a false-negative test. Otherwise, in febrile patients without PSM in the postsurgery period, a positive blood culture was considered a false-positive test and a negative blood culture a true-negative test. Blood cultures were drawn from 266 febrile patients in the postsurgery period. PSM occurred in 38 patients (26 cases due to S. aureus, 8 to Staphylococcus epidermidis, 3 to gram-negative enteric bacteria, and one to Pseudomonas aeruginosa). Within the 60-day postsurgical period, blood culture as a diagnostic test was most accurate in patients with S. aureus bacteremia, providing 68% sensitivity, 98% specificity, a positive predictive value of 87%, and a negative predictive value of 95%. If the analysis was limited to the period during which patients are at maximum risk for PSM (day 7-20), the values in patients with S. aureus bacteremia were as follows: 73% sensitivity, 98% specificity, 90% positive predictive value, and 93% negative predictive value. Blood culture is an accurate test for the early diagnosis of PSM in febrile patients after cardiac surgery, particularly in institutions where S. aureus is prevalent in this context. A negative blood culture practically excludes PSM and, during the period of maximum risk for PSM, the presence of S. aureus bacteremia should compel early surgical management.

Bacteremia↗
PubMed2005

Clinical characteristics and significance of Streptococcus salivarius bacteremia and Streptococcus bovis bacteremia: a prospective 16-year study.

The aim of this study was to determine the clinical significance of Streptococcus salivarius isolates recovered from blood cultures and compare them with isolates of Streptococcus bovis biotypes I and II. Seventeen of the 52 (32%) S. salivarius isolates recovered were considered clinically significant, compared with 62 of the 64 (97%) S. bovis isolates (p<0.0001). Bacteremia caused by S. salivarius occurred mostly in patients who showed relevant disruption of the mucous membranes and/or serious underlying diseases. Patients with S. salivarius bacteremia were younger than those with S. bovis bacteremia (57 vs. 67 years; p<0.01). Patients with S. salivarius bacteremia and patients with S. bovis II bacteremia had similar rates of endocarditis, colon tumors, and non-colon cancer. On the other hand, when compared with S. bovis I bacteremia, S. salivarius bacteremia was associated with lower rates of endocarditis (18% vs. 74%, respectively) (p<0.01) and colon tumors (0% vs. 57%, respectively) (p<0.005) and higher rates of non-colon cancer (53% vs. 9.5%, respectively) (p<0.01). Bacteremia caused by S. bovis II had a hepatobiliary origin in 50% of the patients, while, in contrast, that due to S. salivarius or S. bovis I was less frequently associated with a hepatobiliary origin (12% and 5%, respectively) (p<0.00001). The rate of penicillin resistance was 31% among S. salivarius isolates and 0% among S. bovis isolates (p<0.0001). In conclusion, the clinical characteristics of S. salivarius bacteremia and S. bovis II bacteremia are similar, and the isolation of S. salivarius in blood should not be systematically regarded as contamination.

Adult↗
PubMed2005

Laboratory study of inocula production for composting processes.

Six ligno-cellulolytic fungi were tested regarding to examine their capability to grow on agricultural wastes and produce inocula for composting. Two residues were used: pepper plant wastes and almond shell residues. Results showed the latter as the most adequate substrate for growth of fungi tested. On the contrary, Trichoderma koningii, as well as HLC1 and HLC3, both fungi isolated from almond shell wastes, were able to persist in pepper plant wastes. Modifications of aeration and pH significantly influenced growth of Coriolus versicolor, HLC1 and Phanerochaete. flavido alba and P. flavido alba and Phlebia radiata, respectively, while P. flavido alba was the only microorganism whose growth was not significantly altered by temperature. In competitive assays, where fungi were growth together with other species, growth of both microorganisms isolated from almond shell residues, HLC1 and HLC3, were stimulated while T. koningii showed the better results in sterile conditions.

Agriculture↗
PubMed2005

Environmental tobacco smoke exposure in public places of European cities.

BACKGROUND: Exposure to environmental tobacco smoke (ETS) has important public health implications. The results of the first European multi-centre study that measured ETS exposure in a range of public places (transport, educational settings, and leisure facilities such as bars and restaurants) are presented. METHOD: Nicotine vapour phase was measured using ETS passive samplers containing a filter treated with sodium bisulfate. RESULTS: Bars and discos are the places with the highest concentrations of nicotine from ETS, median ranging from 19 to 122 microg/m(3). Restaurants had the next highest values. Concentrations of nicotine generally range from 0.1-5 microg/m(3) in airports, and from 0.5-10 microg/m(3) in train stations. Nicotine was also found in schools and universities, yet schools tended to have the lowest concentrations compared to all the other public places sampled. In hospitals levels were generally below 5 microg/m(3). CONCLUSIONS: Although there is some variability between cities, this study shows that tobacco smoke is present in most of the studied public places. The study also showed that in areas where smoking is prohibited, concentrations of nicotine are lower than in areas where smoking is allowed but they are not zero. The results of this study indicate that policies should be implemented that would effectively reduce levels of tobacco smoke in public areas.

Air Pollutants↗
PubMed2004

[Changes in tobacco use in the general population of Barcelona, 1983-2000].

OBJECTIVES: To analyze the prevalence trends for smoking and its determinants in the general population of Barcelona from 1983 to 2000. DESIGN: Time series study. SETTING: Health survey based on home interviews of a representative sample of the general population of Barcelona. PARTICIPANTS: In the years 1983, 1992, and 2000 we interviewed 3134, 5004, and 10,000 persons, respectively. MAIN OUTCOME MEASURES AND RESULTS: Between 1983 and 2000 daily tobacco use showed a steady tendency to decrease among men, with a prevalence that decreased from 54.6% to 38.3%, while in women, smoking increased between 1983 and 1992 (from 20.9% to 25.4%) but remained stable in 2000 (24.5%). The proportion of smokers who said they wanted to quit increased in both sexes from 1992 (54.2%) to 2000 (65.7%). During this period the proportion of smokers who said their doctor had advised them to quit increased from 36.1% to 48.1%. The trends for both sexes showed that consumption of tobacco products was greater among less privileged socioeconomic groups. CONCLUSIONS: The results of this study confirm the decrease in the prevalence of daily consumption of tobacco products and the increase in smokers who would like to quit, in parallel with the increase in advice from physicians to quit. However, the trends among younger groups remained stable, a finding that makes it necessary to intensify efforts aimed at this population group.

Adolescent↗
PubMed2004

[Factors associated with smoking onset: 3-year cohort study of schoolchildren].

OBJECTIVE: To analyze the predictors of smoking onset among schoolchildren. METHODS: A cohort study of 1056 children starting in first year secondary school at 44 schools in Barcelona was carried out. Participating children were invited to answer a lifestyle questionnaire every year for 4 years. Each questionnaire carried a personal code to allow the 4 questionnaires to be matched. Matching questionnaires were found for 729 children, 70% of the initial sample. RESULTS: Over the study period, the prevalence of regular smokers increased from 1.7% to 22% among boys and from 1.6% to 38.2% among girls. The predictors of smoking onset among boys were scoring high on the pro-smoking attitudes index (odds ratio [OR]=1.2; 95% confidence interval [CI], 1.1-1.3), intention to smoke in the future (OR=2.2; 95% CI, 1.0-4.9), low self-efficacy in resisting pressures to smoke (OR=0.98; 95% CI, 0.96-0.99), having siblings that smoke (OR=2.5; 95% CI, 1.2-5.4), and spending some free time in bars (OR=2.4; CI, 1.1-4.9). Among girls, the predictors were having low self-esteem (OR=0.94; 95% CI, 0.88-0.99), scoring low on the anti-tobacco attitudes index (OR=0.92; 95% CI, 0.88-0.97), having siblings who smoke (OR=2.5; 95% CI, 1.2-5.5), spending some free time in discotheques (OR=4.5; 95% CI, 1.9-11.8), and living in high socioeconomic-status neighborhoods (OR=3.1; 95% CI, 1.4-10.9). CONCLUSIONS: The results show the importance of cognitive variables as well as a variety of environmental variables, particularly the pattern of free time use and the influence of sibling models. Prevention programs must take into account smoking onset risk factors as a whole.

Adolescent↗
PubMed2004

Determinants of patient delay among tuberculosis cases in Spain.

BACKGROUND: Patient delay was investigated in a cohort of TB patients identified from May 1996 until April 1997 in 13 Autonomous Regions in Spain. The study covered almost 67% of the total Spanish population. METHODS: Data were collected from clinical records. Using unconditional logistic regression with two different cut-off points to define 'patient delay' (the median and 75th percentile), the association between patient delay and different factors was estimated. RESULTS: A total of 7,037 cases were included. Median and 75th percentile delays were 22 and 57 days respectively. Factors associated with patient delay greater than the median (p<0.05) were: non-respiratory symptoms of TB and age over 14 years, although the effect of age was not linear. Furthermore, an interaction was observed between intravenous drug user (IDU) and HIV status, in that, whereas patient delay was greater in IDUs than in non-IDUs among cases whose HIV status was either negative or unknown, among HIV-positive patients no such IDU-related differences were in evidence. Factors associated with extreme patient delay (greater than the 75th percentile) were essentially the same, but the above-described interaction disappeared, with IDU status showing no direct effect. In addition, likelihood of extreme patient delay increased in the case of alcoholism and female gender and decreased in the case of chronic renal failure, corticoid treatment, prison inmates and residents of old age homes. CONCLUSION: Although there is a universally enjoyed right to health care in Spain, some groups of TB patients could nevertheless be experiencing problems in seeking medical attention.

Adolescent↗
PubMed2004

[Changing epidemiology of smoking: Barcelona, 2000-2001].

CONTEXT: In recent years various initiatives of prevention and social changes have been carried out that should have an effect on epidemiology of smoking in our area. Their real effect is little known, however, because of methodological changes in the existing population surveys. In this work the data on smoking in the last city of Barcelona health survey (ESBA 2000-01) are analyzed, with reference to the cumulative information obtained along 18 years from the first survey in 1983. METHOD: ESBA 2000-01 is an interview health survey carried out on a weighted sample with 10,030 people. Data relative to tobacco use are showed for people 15-year-old or older included in the survey, stratified by age, sex, and class. Consumption context variables are also showed, and the tobacco consumption quitting among people who have smoked is analyzed. RESULTS: The proportion of daily smokers in the population over 14 years of age is 29 %, while that of former smokers is 21 % and 2.2 % in this population are occasional smokers. The prevalence is maximum in the 35-44 year-old group, and the prevalence is reduced drastically after this age. Stratified analysis by age, sex, and occupational category shows interesting differences among daily smokers. A strong gradient is observed according to occupational category in males. The situation is more complex in women. The typical smoker began when 17-year-old, and now consumes 16 cigarettes a day. Consumption is somewhat higher in males and is maximum in the 35-44 year-old group. Two-third of the smokers (65.7 %) want to quit smoking and more than one third (36 %) has attempted it along the last year. Almost half of smokers (48.1 %) have received advice to quit smoking from their physician. One of every four (24.9 %) smokers has been warned for smoking in some places. Almost half smokers are the only smoker in their home, and barely a third are the only smokers at work. The proportion of quitting increases with age in both sexes, and nowadays the differences in the probability of quitting smoking are few when the data are stratified by age groups. CONCLUSIONS: These results show the changing pattern of tobacco epidemiology in Barcelona: smoking is no longer the main behavior in no age and sex group, and the only social group in which more than half of its members smoke are 25-44 year-old not qualified worker males. This situation has occurred because of two processes: an important proportion of early quitting (demonstrated even in young adults) and a decrease in the beginning of the habit. Real differences are not observed between males and females with regard to the probability of quitting smoking. These data correct recent estimates that could be influenced by methodological changes in the instruments used.

Adolescent↗
PubMed2003

Isolation of microorganisms for biological detoxification of lignocellulosic hydrolysates.

Acid pretreatment of lignocellulosic biomass releases furan and phenolic compounds, which are toxic to microorganisms used for subsequent fermentation. In this study, we isolated new microorganisms for depletion of inhibitors in lignocellulosic acid hydrolysates. A sequential enrichment strategy was used to isolate microorganisms from soil. Selection was carried out in a defined mineral medium containing a mixture of ferulic acid (5 mM), 5-hydroxymethylfurfural (5-HMF, 15 mM), and furfural (20 mM) as the carbon and energy sources, followed by an additional transfer into a corn stover hydrolysate (CSH) prepared using dilute acid. Subsequently, based on stable growth on these substrates, six isolates--including five bacteria related to Methylobacterium extorquens, Pseudomonas sp, Flavobacterium indologenes, Acinetobacter sp., Arthrobacter aurescens, and one fungus, Coniochaeta ligniaria--were chosen. All six isolates depleted toxic compounds from defined medium, but only C. ligniaria C8 (NRRL 30616) was effective at eliminating furfural and 5-HMF from CSH. C. ligniaria NRRL 30616 may be useful in developing a bioprocess for inhibitor abatement in the conversion of lignocellulosic biomass to fuels and chemicals.

Acids↗
PubMed2003

Temperature effect on Fusarium oxysporum f.sp. melonis survival during horticultural waste composting.

AIMS: The aim of this work was to study the effect of high temperatures generated during composting process, on the phytopathogen fungus Fusarium oxysporum f.sp. melonis. This investigation was achieved by both in vivo (semipilot-scale composting of horticultural wastes) and in vitro (lab-scale thermal treatments) assays. METHODS AND RESULTS: Vegetable residues infected with F. oxysporum f.sp. melonis were included in compost piles. Studies were conducted in several compost windrows subjected to different treatments. Results showed an effective suppression of persistence and infective capacity, as this process caused complete fungal elimination after 2-3 days of composting. In order to confirm the effect of high temperature during this process, in vitro experiments were carried out. Temperature values of 45, 55 and 65 degrees C were tested. All three treatments caused the elimination of fungal persistence. Treatment at 65 degrees C was especially effective, whereas 45 degrees C eliminated fungal persistence only after 10 days. CONCLUSIONS: The composting process is an excellent alternative for the management of plant wastes after harvesting, as this procedure is able to suppress infective capacity of several harmful phytopathogens such as F. oxysporum f.sp. melonis. SIGNIFICANCE AND IMPACT OF THE STUDY: Fusarium oxysporum f.sp. melonis is a plant pathogen fungus specially important in the province of Almería (south-east Spain), where intensive greenhouse horticulture is very extended. High temperatures reached during composting of horticultural plant wastes ensure the elimination of phytopathogen microorganisms such as F. oxysporum f.sp. melonis from vegetable material, providing an adequate hygienic quality in composts obtained.

Cucumis↗
PubMed2003

Bacteraemia in adults due to glucose non-fermentative Gram-negative bacilli other than P. aeruginosa.

BACKGROUND: Glucose non-fermentative Gram-negative bacilli other than P. aeruginosa (NF) are emerging pathogens. AIM: To evaluate the epidemiology, clinical characteristics, predictors of acquisition, and outcome of bacteraemia due to NF. DESIGN: Retrospective analysis of prospectively recorded data. METHODS: We reviewed episodes of NF bacteraemia in patients older than 14 years, recorded through a blood culture surveillance program. Patients were identified at the time of their bacteraemia and prospectively followed. RESULTS: Between January 1991 and December 2000, 296 episodes of NF bacteraemia were detected: 87% were due to Acinetobacter sp., Pseudomonas sp. other than P. aeruginosa, or Stenotrophomonas maltophilia. The global incidence (0.87 cases per 1000 discharges) remained stable during the study period. Patients were of all ages and both sexes, and 282/296 (95.3%) had some predisposing underlying disease or condition, the most common being haematological malignancies without transplantation (85/296, 28.7%), treatment with steroids (78/296, 26.3%), and transplantation (bone marrow or solid organ) (70/296, 23.6%). Fifty (16.9%) were neutropenic. The most common sources of bacteraemia were central venous catheter infection (117/296, 39.5%) and unknown primary site (97/296, 32.8%). Sixty-one episodes (20.6%) were community-acquired and 235 (79.4%) were nosocomial. Forty-three patients (14.5%) died. Pneumonia (RR 1.5, 95%CI 1.1-14.2), age<65 (RR 3.1, 95%CI 1.4-10.3), hospitalization in the intensive care unit (ICU) (RR 3.2, 95%CI 1.3-9.8), rapidly fatal disease (RR 4.9, 95%CI 3.1-12.6), and severe sepsis (RR 9.8, 95%CI 1.6-19.7) were independent predictors of death. Factors predicting the probability that an episode of nosocomial bacteraemia was due to NF included: rapidly fatal disease (RR 1.23, 95%CI 1.02-4.1), age<65 (RR 2.05, 95%CI 1.4-3), hospitalization in the ICU (RR 2.06, 95%CI 1.4-3, and pneumonia (RR 2.1, 95%CI 1.05-4.8). DISCUSSION: NF bacteraemia mainly affects patients with malignant haematological disease, with and without transplantation, and patients in the ICU. The most common known source is a central venous catheter, though many sources are unknown. Mortality is relatively low, and depends on the severity of the underlying disease.

Adolescent↗