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Biomedical subjects

M Alvarez

Publications and source records attributed to M Alvarez.

At least 19 recordsLinked to original sources
PubMed2006

The Meropenem Yearly Susceptibility Test Information Collection antimicrobial susceptibility program in Spain: a 5-year analysis.

The Meropenem Yearly Susceptibility Test Information Collection program is a global study providing in vitro surveillance data on antimicrobial susceptibility in centers prescribing meropenem. This study summarizes data on the activity of meropenem and 5 comparators against 4022 clinical isolates from 7 centers in Spain (1999-2003). Those bacteria intrinsically resistant to meropenem were excluded. Among Enterobacteriaceae, 100% of Enterobacter spp., Citrobacter spp., and Serratia spp. were susceptible to meropenem. Escherichia coli and Klebsiella pneumoniae susceptibilities to carbapenems were 100% and > or =98%, respectively. Extended-spectrum beta-lactamase-producing Enterobacteriaceae were 3.8% of isolates, and all of them were susceptible to meropenem. Ciprofloxacin resistance in E. coli was around 20%. Meropenem and piperacillin/tazobactam were the most active agents against Pseudomonas aeruginosa. Acinetobacter baumannii were 61-90% susceptible to carbapenems, but only 6-21% susceptible to ciprofloxacin. In this period, around 100% of oxacillin-susceptible staphylococci were susceptible to meropenem. There was no significant decrease in susceptibility to the carbapenems throughout the 5-year period. The clinical use of meropenem in 7 Spanish centers did not increase bacterial resistance to this agent in the microorganisms evaluated.

Academic Medical Centers↗
PubMed2006

Effects of early high-dose levothyroxine treatment on auditory brain event-related potentials at school entry in children with congenital hypothyroidism.

AIMS: We tested whether brain event-related potentials (ERPs) are normal in children with congenital hypothyroidism (CH) after early high-dose levothyroxine treatment. METHODS: Auditory ERPs were recorded in 33 normal controls and in 15 children with CH at 5 years 9/12. Based on bone maturation at diagnosis, the CH group was divided into severe (n = 8) and moderate (n = 7) subgroups. CH patients were treated at a median age of 14 days with a mean initial dose of levothyroxine of 11.6 microg/kgxday. Two ERP components (N100 and N200) were measured and clinical follow-up variables collected. RESULTS: The functional anatomical and cognitive organisation of the auditory system, as revealed by the analyses of ERP measures, did not differ between CH and controls, or between severe and moderate CH subjects. However, N200 latency was globally longer in the CH than in the control group (p = 0.01) and was positively correlated with the over-treatment index (r = 0.61; p < 0.05) and verbal IQ. N200 amplitude was negatively correlated with initial dose (r = -0.74; p < 0.005). CONCLUSION: These data suggest that sensitive tools such as ERPs can reveal differences between CH and controls and relate these differences to the adequacy of treatment of CH.

Child, Preschool↗
PubMed2006

Influence of breed and age on morphometry and depth of inseminating catheter penetration in the ewe cervix: a postmortem study.

A detailed examination of the cervical canal in the ewe was carried out. This analysis could be used to design new catheters for artificial insemination (AI) to achieve deeper cervical penetration and therefore better fertility results. Three hundred and sixty-five cervices from four sheep breeds (Churra, Assaf, Merino, Castellana) obtained postmortem were used. Cervix morphometry and depth of cervical penetration using two types of catheters were determined. A conventional straight catheter for ovine artificial insemination (IMV), and a bent catheter, ending in a stainless steel needle, 9 cm in length and with an 8 mm tip bent 45 degrees , were used. The results showed that the morphometry of the cervix depends on breed and age of the ewe. The cervices of Churra breed were shorter and narrower, and had a higher number of folds than those of other breeds. Postmortem cervical penetration was deeper when the cervices were longer and wider, and with fewer folds (Merino and Castellana breeds). In ageing ewes, the cervix tended to become longer and wider, with loose folds. This decreased structural complexity and significantly improved cervical penetration. The bent catheter allowed significantly greater cervical penetration than the straight IMV one.

Age Factors↗
PubMed2006

Predictive factors of treatment interruption duration in a cohort of HIV-1 infected patients with CD4 count greater than 350 cells per mm3.

OBJECTIVE: To determine predictive factors of treatment interruption (TI) duration within a cohort of HIV-1 infected patients having stopped their treatment with CD4 above 350 cells per mm(3). DESIGN: Data were collected from computerized medical records. Patients were selected if they were HIV-1 positive, 18 years of age or older, and had stopped their treatment between January 1st, 1999 and July 1st, 2003, with CD4 count above 350 cells per mm(3). The study period was censored on October 1st, 2003. Patients were assessed every 3 months from inclusion to censure. A survival analysis using the Cox proportional hazard model was performed. RESULTS: One hundred eighty-five patients were included. The median duration of TI was 43 weeks. Sixty-three patients remained off-treatment at censure. In the multivariate analysis, TI duration was shorter if CD4 nadir was below 250 cells per mm(3) before TI (relative hazard, 2.10), age superior to 40 (relative hazard, 1.72), viral load higher than 2.3 log.copies per ml (relative hazard, 1.52), and CDC class C (relative hazard, 1.78) at TI. Neither CD4 cell count at TI, numbers of treatments, nor duration of treatment and infection before TI were independent predictive factors of early treatment resumption (TR). CONCLUSION: Some clinical and biological data may be used as predictive factors of early TR. Our results can have implications on future therapeutic strategies, in which the goal of therapy is to maintain CD4 cell count above a predetermined threshold using cycles of therapy followed by prolonged interruption according to CD4 count.

Acquired Immunodeficiency Syndrome↗
PubMed2006

N-acetyl-cysteine protects liver from apoptotic death in an animal model of fulminant hepatic failure.

BACKGROUND: This work was undertaken to investigate whether treatment with N-acetyl-cysteine (NAC) prevents oxidative stress and inhibits the apoptotic pathways in an animal model of fulminant hepatic failure. METHODS: Rabbits were experimentally infected with 2x10(4) hemagglutination units of a rabbit hemorrhagic disease virus isolate. RESULTS: The spontaneous mortality rate of infected animals was 67% at 36 h post infection (pi) and 90% at 48 h pi. This percentage decreased significantly in animals receiving an i.p. injection of NAC (150 mg/kg body way/daily), for 7 days prior to infection. From 36 h pi marked increases were detected in blood levels of transaminases, lactate dehydrogenase, bilirubin and the oxidised/reduced glutathione ratio. All these effects were significantly prevented by NAC treatment. The Bax to Bcl-2 relative expression, the expression of FasL, cytochrome c and PARP-1, and the activity of caspase 3 were significantly increased at 36 and 48 h pi in infected animals. These changes were markedly reduced in animals treated with NAC, with the exception of FasL. CONCLUSION: Our results suggest a potential hepatoprotective role of NAC in fulminant hepatic failure, mediated partially through the modulation of the intrinsic pathway of apoptosis.

Acetylcysteine↗
PubMed2006

Ovum pick-up in sheep: a comparison between different aspiration devices for optimal oocyte retrieval.

In vivo ovum pick-up (OPU) in sheep may be improved with a proper choice of aspiration elements (needle and tubing) and aspiration vacuum pressure. In the present study, two experiments were carried out. In Expt 1, visible follicles in ovaries of slaughtered ewes (treated separately according to their diameters: small<3 mm, medium 3-5 mm and large>5 mm) were aspirated using different combinations of the three studied factors such as aspiration flow rate (10, 20, 30, 40 and 50 ml water/min), needle gauge (18 and 20 G) and tubing inner diameter (1, 2 or 3 mm internal diameter). In Expt 2, a study with two 18 G needles of different lengths (18 G: 82 mm; 18 GL: 600 mm) was carried out, using ovaries obtained post-mortem, and performing in vivo laparoscopic follicular aspiration on ewes. We considered good quality oocytes as those with both complete compact cumulus and a homogeneous cytoplasm. Recovery rate, proportion of good quality oocytes (good quality oocytes/100 oocytes recovered) and overall efficiency (good quality oocytes/100 follicles aspirated) were noted. In Expt 1, aspiration flow rate affect remarkable proportion of good quality oocytes (69.5%, 50.5%, 44.8%, 36.5% and 28.3% for flows from 10 to 50 ml/min respectively, p<0.05). Needle gauge did not affect aspiration device efficiency. Thin and intermediate tubings were more effective (overall efficiency rates: 34.9%, 32.3% and 28.1% for 1, 2 and 3 mm respectively, p<0.05). Follicle size did not affect recovery rate, but proportion of good quality oocytes was higher for large (77.9%) and medium (64.4%) follicles (p<0.05). Finally, some combinations of the aspiration device showed greater effectiveness. In Expt 2, needle length did not influence recovery rate, but good quality oocytes rate was significantly modified both post-mortem and in vivo (good quality rate for 18 G vs 18 GL needles: 69.5% vs 47.7% and 58.1% vs 25.4%, post-mortem and in vivo respectively, p<0.05). We conclude that low-aspiration flow rates (10 and 20 ml/min) with thin or intermediate tubings (1 and 2 mm), and any short needle (18 G or 20 G) are the most adequate aspiration factors for OPU in sheep.

Animals↗
PubMed2006

Improvement strategies in ovine artificial insemination.

Artificial insemination in ram is scarcely widespread comparing with other domestic species. This has been due not only to fertility results being irregular and low but also because of the difficulty in the application of enhancements such as the use of frozen-thawed sperm. Although there is a lot of information on the use of different options to improve these AI results (such as transcervical application, the use of thawed sperm, etc.) commercial programmes can be classified on two general categories: those using refrigerated semen (15 degrees C) by superficial intracervical deposition (vaginal), and, more restricted, those using thawed sperm by intrauterine deposition (laparoscopy). In the present work, we have summarized our viewpoint on three general research lines for the improvement of AI results in sheep: semen preservation, AI procedures and semen assessment. Briefly, in ram it is necessary to develop a medium term methodology of sperm refrigeration (3-5 days), which would allow the distribution of sperm doses to a widespread area. Nevertheless, it is also necessary to develop an intrauterine transcervical AI technique, which allows thawed semen to be applied by vaginal insemination. Besides, the low predictive value of classic assessment techniques limits the ability to adjust the number of spermatozoa per dose according to its actual fertility.

Animals↗
PubMed2005

The effect of octyl glucoside on rheological behavior of diluted and concentrated lamellar phases.

We have investigated the rheological properties of lamellar liquid crystal formed by nonionic surfactants at low and high surfactant concentrations with a small amount of octyl glucoside and their relationship with the topology of the bilayer. Rheology is a specific signature of each bilayer topology. The decrease in viscosity by increasing the shear rate according to a power law with exponent close to -0.8 was found for the concentrated system of LSB/1-butanol/water and 1% in weight of OG. On the contrary, the decrease in the viscosity by increasing the shear rate for the diluted system is less pronounced with lower exponent values. The rheological data agrees with the presence of vesicles. A special case is the system with benzyl alcohol. The apparent viscosity does not follow the same power law than for alkanols.

1-Butanol↗
PubMed2005

Highly sensitive polymer-based cantilever-sensors for DNA detection.

We present a technology for the fabrication of cantilever arrays aimed to develop an integrated biosensor microsystem. The fabrication process is based on spin coating of the photosensitive polymer and near-ultraviolet exposure. Arrays of up to 33 microcantilevers are fabricated in the novel polymer material SU-8. The low Young's modulus of the polymer, 40 times lower than that of silicon, enables to improve the sensitivity of the sensor device for target detection. The mechanical properties of SU-8 cantilevers, such as spring constant, resonant frequency and quality factor are characterized as a function of the dimensions and the medium. The devices have been tested for measurement of the adsorption of single stranded DNA and subsequent interstitial adsorption of lateral spacer molecules. We demonstrate that sensitivity is enhanced by a factor of six compared to that of commercial silicon nitride cantilevers.

Biosensing Techniques↗
PubMed2005

Season effect on genitalia and epididymal sperm from Iberian red deer, roe deer and Cantabrian chamois.

Seasonality deeply affects the physiology and behavior of many species, and must be taken into account when biological resource banks (BRBs) are established. We have studied the effect of seasonality on many reproductive parameters of free-ranging Iberian red deer, roe deer and Cantabrian chamois, living in Spain. Testicles from hunted animals were collected and sent to our laboratory at different times during the year. We recorded the weight and volume of testis, the weight of the epididymis and its separate parts (caput, corpus, and cauda), the weight of the sperm sample collected from the cauda epididymis, and several sperm parameters (sperm concentration, spermatozoa recovered, motility, HOS test reactivity, acrosomal status, and viability). We studied the data according to several periods, defined accordingly to each species. For red deer, we defined rut (mid-September to mid-October), post-rut (mid-October to mid-December), and non-breeding season (February). For roe deer, they were pre-rut (June), rut (July), post-rut (first fortnight of August), and non-breeding season (September). For chamois: non-breeding season (June to mid-September) and breeding season (October-November). The rut/breeding season yielded significantly higher numbers for almost all parameters. However, in the case of red deer, sperm quality was higher in the post-rut. For roe deer, testicular weight was similar in the pre-rut and in the rut, and sperm quality did not differ significantly between these two periods, although we noticed higher values in the rut. In the case of chamois, sperm quality did not differ significantly from the breeding season, but data distribution suggested that in the non-breeding season there are less males with sperm of good quality. On the whole, we find these results of interest for BRB planning. The best season to collect sperm in this species would be the breeding season. However, post-rut in red deer, pre-rut in roe deer, and non-breeding season in chamois could be used too, because of the acceptable sperm quality, despite the lower quantity salvaged. More in-depth research needs to be carried out on the quality of sperm salvaged at different times of the year in order to confirm these findings.

Acrosome↗
PubMed2005

Factors influencing the success of vaginal and laparoscopic artificial insemination in churra ewes: a field assay.

Pregnancy rate following artificial insemination (AI) in sheep is variable depending on several factors. The Churra breed (milk breed of the North-West of Spain) yields lower fertility results compared with other local and European breeds (Manchega, Latxa, Merino, Lacaune, Sarde, etc.). In this work we studied the influence of many factors on the fertility of the Churra breed (insemination technique, year, farm, age, male, number of inseminations per ewe, lambing-insemination interval and technician), analyzing lambing data obtained after 44448 inseminations (39.67% cervical AI via vagina, AIV, and 60.33% intrauterine AI using laparoscopy, AIL) in a categorical model. The most important factors influencing fertility after AI were farm, year, season, AI technique, and technician. AIL showed significantly higher fertility results than AIV (44.89% versus 31.25%). Season significantly affected fertility in both cases, but differences were more evident in AIV. Fertility dropped 1.74% (AIV) and 2.07% (AIL) per year as the ewes aged. Finally, AI fertility decreased when the lambing-insemination interval was lower than 10 weeks.

Aging↗
PubMed2005

Bacillus cereus infections in Traumatology-Orthopaedics Department: retrospective investigation and improvement of healthcare practices.

OBJECTIVE: To investigate 41 open fractures infected with Bacillus cereus in a Traumatology-Orthopaedy ward and propose a care protocol at admission. METHODS: All B. cereus strains isolated from patients hospitalized in the Traumatology-Orthopaedy ward between March 1997 and August 2001 were submitted to molecular analysis (RAPD and PFGE) in order to investigate a putative outbreak. Susceptibility to the main antibiotics and antiseptics used in this kind of surgery was also evaluated. RESULTS: The B. cereus clinical isolates were mainly isolated from patients who had initially open fractures and were not clonally related. Furthermore, analysis of the clinical data was in favour of a telluric contamination of the wound (wound contamination with terrestrial environments) before admission. Finally, betalactam antibiotics used for prophylactic chemotherapy were not effective against the strains tested as well as the antiseptics who displayed poor effect. CONCLUSION: B. cereus could be termed an emerging pathogen and people need to be aware of its potential importance in orthopaedic trauma cases. In this purpose, a systematic screening for B. cereus at admission should be necessary in front of patients with open fractures associated with telluric contamination. Furthermore, if this bacterium can be isolated, chemotherapy should be based upon ciprofloxacin that would prevent the development of B. cereus infection responsible for deleterious complications.

Adolescent↗
PubMed2005

[Clinical picture and prognostic factors for severe community-acquired pneumonia in adults admitted to the intensive care unit].

OBJECTIVE: In Chile very little information is available on severe community-acquired pneumonia treated in intensive care units. This study describes the clinical picture, prognostic factors, and treatment of adult patients admitted to the intensive care unit for severe community-acquired pneumonia. PATIENTS AND METHODS: A total of 113 consecutive patients were included in this prospective, descriptive study. RESULTS: The mean (SD) age of the 113 patients was 73 (15). Of these, 95% had associated comorbidity, and 81% were in the high-risk classes of the Pneumonia Severity Index. Etiology was identified in 31%, and the most common pathogens were Streptococcus pneumoniae (40%), gram negative bacilli (17%), and Mycoplasma pneumoniae (6%). The main complications were the need for mechanical ventilation (45%), septic shock (26%), heart failure (24%), and arrhythmias (15%). Mortality at 30 days was 16.8%, and multivariate analysis revealed the following factors to be associated with a greater risk of death: acute renal failure (odds ratio: 5.1), and glycemia above 300 mg/dL (odds ratio: 7.2). CONCLUSIONS: The patients with severe pneumonia admitted to the intensive care unit are elderly, with a high level of comorbidity and complications, but most survive.

Adult↗
PubMed2005

In vitro activity of telithromycin against mefA and ermB erythromycin-resistant viridans streptococci isolated from bacteremia of oral origin in Spain.

Erythromycin-resistant viridans streptococci are often responsible of bacteremias following dental manipulations. The aim of this study was to evaluate the in vitro activity of telithromycin against erythromycin-susceptible and erythromycin-resistant viridans streptococci. Venous blood samples were collected from 84 patients, 30 s after dental extractions. Viridans streptococci were identified by conventional microbiological techniques. A set of 36 viridans streptococci were selected to investigate the in vitro activity of telithromycin by the agar dilution method. Macrolide resistance genes were amplified with specific primers for the mefA and ermB genes and visualized by electrophoresis. For erythromycin-susceptible viridans streptococci, telithromycin minimal inhibitory concentration90 (MIC90) was <0.008 microg/ml. For erythromycin-resistant viridans streptococci, telithromycin MIC90 was 1 microg/ml. The MIC90 to telithromycin of the mefA-positive and ermB-negative viridans streptococci was lower than that of the mefA-negative and ermB-positive viridans streptococci (0.128 microg/ml versus 1 microg/ml). The in vitro activity of telithromycin was high, irrespective of the erythromycin susceptibility and the mechanism of erythromycin resistance identified.

Anti-Bacterial Agents↗
PubMed2005

Isolation, tissue distribution, and molecular characterization of Toxoplasma gondii from free-range chickens from Guatemala.

The prevalence of Toxoplasma gondii in free-ranging chickens is a good indicator of the prevalence of T. gondii oocysts in the soil because chickens feed from the ground. The prevalence of T. gondii in 50 free-range chickens (Gallus domesticus) from Guatemala was determined. Antibodies to T. gondii were assayed by the modified agglutination test (MAT). Antibodies were found in 37 (74%) chickens with titers of 1:5 (11), 1:10 (7), 1:20 (11), 1:40 (1), 1:80 (1), 1:160 (3), 1:1,280 (2), and 1:2,560 (1). Hearts, pectoral muscles, and brains of 19 chickens with MAT titers of 1:20 or more were bioassayed individually in mice. Tissues from the remaining 31 chickens with titers of 1:10 or lower were pooled and fed to 4 T. gondii-free cats (13 chickens with titers of less than 1:5 to 1 cat, 11 chickens with titers of 1:5 to 2 cats, and 7 chickens with titers of 1:10 to 1 cat). Feces of cats were examined for oocysts; they did not shed oocysts. Toxoplasma gondii was isolated from 8 chickens with MAT titers of 1:20 or more (from 1 of 11 chickens with a titer of 1:20 and all 7 chickens with a titer of 1:80 or more) from the heart, brain, and pectoral muscle (3); heart and pectoral muscle (1); and heart alone (4). Genotyping of these 8 isolates with the SAG2 locus indicated that 5 were type III and 3 were type 1. This is the first report of isolation of T. gondii from chickens from Guatemala.

Agglutination Tests↗