Search PubMed⌕ Search

Biomedical subjects

A Valle

Publications and source records attributed to A Valle.

At least 19 recordsLinked to original sources
PubMed2006

Structural and functional characterization of a recombinant sticholysin I (rSt I) from the sea anemone Stichodactyla helianthus.

Sticholysins I and II (Sts I and II) are two potent cytolysins from the sea anemone Stichodactyla helianthus. These isoforms present 13 substitutions, with three non-conservative located at the N-terminus. St II is considerably more hemolytic than St I in human red blood cells, a result explained by the smaller number of negatively charged groups present at St II's N-terminus. In the present work, we have obtained a recombinant St I (rSt I), differing from the wild type in a single amino acid residue (E16Q). This pseudo-wild type is structurally similar to St I and shows a similar capacity to interact with and form pores in model membranes. This was assessed by the intrinsic fluorescence increase in the presence of liposomes, their adsorption to bilayers (measured by SPR), their concentration at the air-water interface, their interaction with lipid monolayers and their capacity to promote the release of carboxyfluorescein entrapped in liposomes. In spite of these similarities, rSt I presents a larger hemolytic activity in human red blood cells than St I, being intermediate in activity between Sts I and II. The results obtained in the present work emphasize that even the change of one single E by Q at the N-terminal segment may modify the toxin HA and show that this functional property is the most sensitive to subtle changes in the protein primary structure.

Amino Acid Sequence↗
PubMed2006

The microbial degradation of azimsulfuron and its effect on the soil bacterial community.

AIMS: Azimsulfuron is a recently introduced sulfonylurea herbicide useful in controlling weeds in paddy fields. To date very little information is available on the biodegradation of this pesticide and on its effect on the soil microbial community. The aim of this work was to study its biodegradation both in slurry soil microcosms and in batch tests with mixed and pure cultures. METHODS AND RESULTS: Azimsulfuron was applied to forest bulk soil in order to study its effect on the structure of the bacterial soil community, as detectable by denaturant gradient gel electrophoresis (DGGE) analyses. Biodegradation and abiotic processes were investigated by HPLC analyses. In addition, a microbial consortium was selected, that was able to use azimsulfuron as the sole energy and carbon source. One of the metabolites produced by the consortium was isolated and identified through LC-MS analyses. Cultivable bacteria of the consortium were isolated and identified by 16S rDNA sequencing (1400 bp). CONCLUSIONS: Azimsulfuron treatment seems to have the ability to cause changes in the bacterial community structure that are detectable by DGGE analyses. It is easily biodegraded both in microcosms and in batch tests, with the formation of an intermediate that was identified as 2-methyl-4-(2-methyl-2H-tetrazol-5-yl)-2H-pyrazole-3-sulfonamide. SIGNIFICANCE AND IMPACT OF THE STUDY: The study increases the knowledge on the biodegradation of azimsulfuron and its effects on the soil microbiota.

Bacteria↗
PubMed2005

Sex-related differences in energy balance in response to caloric restriction.

Sex-related differences in energy balance were studied in young Wistar rats fed standard chow pellets either ad libitum or in restricted amounts (60% of ad libitum intake) for 100 days. Caloric intake, indirect calorimetry, organ and adipose tissue weights, energy efficiency, liver mitochondrial respiration rate, and brown adipose tissue (BAT) uncoupling protein-1 (UCP1) content were measured. Ad libitum-fed females showed greater oxygen consumption (Vo(2)) and carbon dioxide production (Vco(2)) and lower energy efficiency than males. Caloric restriction induced a chronic drop of Vo(2) and Vco(2) in females but not in males over the period studied. Restricted females showed a better conservation of metabolic active organ mass and a greater decrease in adipose depots than restricted males. Moreover, changes of BAT size and UCP1 content suggest that BAT may be the main cause responsible for sex differences in the response of energy balance to caloric restriction. In conclusion, our results indicate that females under caloric restriction conditions deactivate facultative thermogenesis to a greater degree than males. This ability may have obvious advantages for female survival and therefore the survival of the species when food is limiting.

Adaptation, Physiological↗
PubMed2003

Nonlinear polarization dynamics in directly modulated vertical-cavity surface-emitting lasers.

A current-modulated vertical-cavity surface-emitting laser is shown to exhibit interesting nonlinear dynamics in its two orthogonal linearly polarized (LP), fundamental transverse modes. The intensities of the two LP modes may exhibit in-phase time-periodic dynamics or chaotic regimes with combination of in-phase and antiphase dynamics at two different time scales. Chaotic dynamics are found in a large range of laser and modulation parameters.

Journal Article↗
PubMed2003

Comparison of pore-forming ability in membranes of a native and a recombinant variant of Sticholysin II from Stichodactyla helianthus.

Sticholysin II (St II) a potent cytolysin from the sea anemone Stichodactyla helianthus was obtained by recombinant procedures exhibiting six histidine residues in its N-terminus (St IIn6H). The functional comparison between St II and St IIn6H showed a lesser pore-forming ability for the recombinant than for the native in human or rat red blood cells (RBC) and in large unilamellar vesicles (LUV) of different phospholipid composition. However, binding of St IIn6H to small unilamellar vesicles (SUV) was higher with regard to St II. The explanation to the different permeabilizing capacity of both protein variants is not clear, but a different anchoring of St IIn6H to the lipid bilayer could delay the organization of the competent pore into membrane.

Amino Acid Substitution↗
PubMed2002

Laboratory-scale trials of electrolytic treatment on industrial wastewaters: microbiological aspects.

Animal, civil and industrial waste matter is a source of potential chemical, microbiological and air pollutants. In populated areas the presence of faecal bacteria and the production of malodorous compounds during waste storage and in the tanks of wastewater treatment plants, can cause concern. The general aim of the work was to study electrolytic waste treatment (recently applied on animal slurry) using low electric current across graphite and copper electrodes, determining its effect on the microflora of sludge, collected from the equalisation basin of an industrial aerobic wastewater treatment plant, and on odour emission abatement. Biochemical and enzymatic indicators like ATP content and a pool of 19 enzymatic activities were tested, comparing them with viable cell counts by traditional microbiological methods, to verify the validity of such indicators in monitoring the electrolytic treatment and to assess their correlation with odour reduction. The preliminary results of our laboratory-scale trials showed that in the presence of inert electrodes, such as graphite, metabolic activity is stimulated, whereas with copper electrodes the ATP content and some enzymatic activities are inhibited quite considerably after only four days, this being accompanied by a marked reduction in odour. Consideration was also given to the total copper released from the electrodes and its recovery using iron electrodes.

Air Microbiology↗
PubMed2001

Caesarean sections in Mexico: are there too many?

This paper seeks to quantify the magnitude of caesarean sections in Mexican public health-care institutions in recent years, to characterize the evolution of caesarean section rates (CSR) during the last decade, and to estimate the possible economic cost caused by the excess of caesareans performed in these institutions. The study is based on data obtained from the health sector, both for Mexico in the 5-year period 1993-97 and for the Mexican State of Jalisco between 1983 and 1998. Linear regression analysis was used to evaluate time series, and "excess of caesareans" was considered the number of caesarean deliveries performed above the admissible 15% CSR. The results reflect that on the national level, more than one-quarter of the deliveries handled by public institutions ended in caesarean section for each analyzed year, and if the deliveries performed in private institutions are included, the national rate is around 30%. A marked increase in CSR can be observed in Jalisco between 1983 and 1998 (almost 50%); and the cost for the nation of this CSR excess in financial terms is highly significant: several millions of dollars--obtained from public funds--are spent annually and unnecessarily by health services. The findings suggest that the increase in CSR is a public health problem that has not been satisfactorily faced by the health sector authorities. Many unnecessary caesareans would undoubtedly be avoided if the policies of these public health-care institutions were to consider, as a priority, both the known higher risk implicit in a caesarean for the health of the mother and child, and the economic impact on the country and its health institutions of the excessive number of caesareans performed yearly.

Cesarean Section↗
PubMed1999

Genetically distinct dog-derived and human-derived Sarcoptes scabiei in scabies-endemic communities in northern Australia.

Overcrowding is a significant factor contributing to endemic infection with Sarcoptes scabiei in human and animal populations. However, since scabies mites from different host species are indistinguishable morphologically, it is unclear whether people can be infected from scabies-infested animals. Molecular fingerprinting was done using three S. scabiei-specific single locus hypervariable microsatellite markers, with a combined total of 70 known alleles. Multilocus analysis of 712 scabies mites from human and dog hosts in Ohio, Panama and Aboriginal communities in northern Australia now shows that genotypes of dog-derived and human-derived scabies cluster by host species rather than by geographic location. Because of the apparent genetic separation between human scabies and dog scabies, control programs for human scabies in endemic areas do not require resources directed against zoonotic infection from dogs.

Alleles↗
PubMed1998

Ascites free-water dynamics in decompensated cirrhosis: effects of an acute Hemaccel infusion.

BACKGROUND: Plasma-expanders (PE) are commonly employed to reduce the hemodynamic effects of large-volume paracentesis in patients with decompensated cirrhosis. The aim of this paper is to investigate the effects of PE acute administration on ascites dynamics in cirrhotic patients. METHODS: Wash-out intraabdominal pressure (IAP), ascites volume and free-water peritoneal clearance (FWPC) were evaluated in six decompensated cirrhosis by means of a methylene-blue (MB) dilution method. The method is based on the compartmental analysis of MB peritoneal clearance and has been validated by previous deuterium oxide studies. Immediately after the MB dilution test, a rapid Hemaccel i.v. infusion (500 ml 3.5% in 15 min) was perform-ed in all subjects, thereafter carrying out a second MB test. The obtained results were analyzed by two-way variance analysis. RESULTS: IAP and ascites volume values were not appreciably modified by the PE treatment. Following the Hemaccel infusion, only a fair reduction of FWPC values (from 88.33+/-7.78 to 76.98+/-8.09 ml/min) was observed. CONCLUSIONS: The results obtained indicate that, at least at the employed doses, Hemaccel acute administration has a low impact on the ascites dynamics in decompensated cirrhotics. These data cannot therefore support the hypothesis of a therapeutic use of PE in ascitic patients, but to avoid excessive plasma volume reductions in association with a large volume paracentesis.

Journal Article↗
PubMed1998

[Outbreak of nosocomial diarrhea by Clostridium difficile in a department of internal medicine].

BACKGROUND: Clostridium difficile (DCD) is the main etiologic agent of nosocomial diarrhea of infectious origin. Most of the cases of DCD have been detected in a hospital environment. PATIENTS, MATERIAL AND METHODS: From October to November 1996 five cases of nosocomial diarrhea were detected with the presence of the toxin A of Clostridium difficile being observed in the stools. These patients were compared with a group of 19 patients without diarrhea (controls) who were admitted to the same ward during the same period as the patients with DCD. RESULTS: The hospital stay of the cases was greater (25 +/- 8 days) than that of the controls (14 +/- 10 days; p < 0.05). One hundred percent of the cases received antibiotics during admission (2 +/- 1.2 antibiotics per patient), versus 68% of the controls (1.1 +/- 0.9 antibiotics per patient, p > 0.05). The length of antibiotic treatment prior to the onset of the symptoms was 8 +/- 3 days (range 7-11 days). The type of antibiotic administered was similar in both groups. More of the cases with DCD (60%) had vesicle catheterization than the controls (11%, p < 0.05). All the patients with DCD presented abdominal pain and several liquid stools per day without blood or pus (3.2 +/- 0.45 stools per patient) and 2 (40%) fever. The mean length of diarrhea was 5.6 +/- 3.6 days. The serum albumin concentration on the first day of admission was significantly lower in the cases of DCD (2.9 +/- 0.4 mg/dl) than in the controls (3.3 +/- 3.4 mg/dl, p < 0.05). All the cases received antibiotic treatment for Clostridium difficile (oral metronidazol or vancomycin) with good clinical evolution. CONCLUSIONS: The patients with DCD had more often had vesicle catherization and presented a lower serum albumin concentration than the controls.

Adult↗
PubMed1998

Colovaginal anastomosis: a unique complication of end-to-end anastomosis stapler use in low anterior resection.

Anastomotic staplers have been used in colorectal surgery for several years. End-to-end stapler use for low anterior resection, as well as for other procedures, is common in surgical practice. These staplers have allowed more extended, lower resections of the colorectum without loss of bowel continuity or sphincter function. There have been reported complications of stapler use, with anastomotic stricture and leakage being the most common. We report here a unique complication of direct colovaginal anastomosis using the end-to-end stapler during a low anterior resection of an early-stage rectal adenocarcinoma.

Adenocarcinoma↗
PubMed1997

[Bipolaris australiensis in a Spanish patient with allergic chronic sinusitis].

Allergic fungal sinusitis is a disease that results from hypersensitivity reaction of the host against fungi colonizing the paranasal sinuses. A 36 years old Spanish man with no history of travel abroad had a history of asthma, nasal polyps, allergic rhinitis and a chronic sinusitis with nasal congestion and headaches. Computed tomography showed pansinusitis and opacification of the paranasal sinuses. A pure culture of Bipolaris australiensis was grown from sinus tissues. Infections caused by Bipolaris spp. and treatment regimes are discussed.

English Abstract↗
PubMed1996

Estimating the sensitivity of cervical cytology: errors of interpretation and test limitations.

The objective of this study was to estimate: (i) the sensitivity of cytologists in recognizing abnormal smears; (ii) the sensitivity of cervical cytology as a method of detecting abnormal smears among those obtained in the presence of cervical intraepithelial neoplasia (CIN). Study subjects were 61 women with a histologically confirmed CIN identified through colpohistological and cytologic screening. For objective (i) new smears were taken from study subjects just before treatment, mixed with routine preparations, interpreted by unaware cytologists and then blindly reviewed by a group of three expert supervisors, who reached a consensus diagnosis. Cytologists classified as positive for squamous intraepithelial lesion (SIL) 30 of the 34 smears judged as positive by supervisors (100% of smears classified as high-grade and 67% of smears classified as low-grade SIL by the supervisors). Our approach, based on creating a set of smears with a high a priori probability of being positive, proved to be an efficient way of estimating errors of interpretation. For objective (ii), smears taken at the moment of diagnosis, just before biopsy, were also reviewed by the same supervisors. These CIN cases were identified among asymptomatic women independently of cytological findings and results are therefore not subject to verification bias. Among the 33 histological CINII/III, four (12%) smears had no atypical cells (three negatives and one unsatisfactory) at review. The same proportion was 26% (four negatives and one unsatisfactory) among the 19 histological CINI. No significant differences in smear content were found between the seven 'false negatives' and a sample of 'true positive' and 'true negatives' for a number of formal adequacy criteria (including presence of endocervical cells). Strong differences were found between positive smears taken just before biopsy and those taken just before treatment (in 11 women the first smear only was positive, while the opposite was never observed), suggesting an effect of punch biopsy in removing lesions.

Diagnostic Errors↗
PubMed1996

Constitutional delay in growth and puberty: a comparison of final height achieved between treated and untreated children.

Constitutional delay in growth and puberty (CDGP) is one of the principal causes of consultation due to short height. Frequently familial short stature is associated with the CDGP. The predicted final height is reached in the majority of the cases but some individuals do not achieve their target height. Poor growth, especially during the pubertal years, as well as a short or growth delayed mother are some of the negative factors for final outcome. Some prepubertal children show a transient diminished GH secretion that normalizes during puberty. Therapy with hGH or oxandrolone increases growth velocity but does not ameliorate final height. The psychosocial situation of the children is the most important condition to treat with testosterone, estrogens or oxandrolone. In view of the results hGH should not be administered routinely to these cases. It remains open which children could benefit from hGH therapy.

Body Height↗
PubMed1993

Induction of labor with intravaginal prostaglandin E2 gel.

OBJECTIVE: The aim of our study was to evaluate the optimum dose of intravaginal prostaglandin E2 gel for induction for labor in nulliparous women with a relatively ripe cervix (modified Bishop score 4 or 5). METHOD: One hundred and sixty-seven nulliparous women at term with indications for the induction of labor were treated randomly with two doses of intravaginal 2.0 (group A) or 3.0 mg (group B) of prostaglandin PGE2 gel every 12 h. Data were analyzed by chi 2-test and Student's t-test. RESULTS: Of 87 patients 64 went into labor after gel application in group A, compared with 68/80 in group B (73.5% vs. 85.0%) (P = NS). A second gel administration was needed for 9 women in group A and 6 women in group B. More side effects (both local and systemic) were noted in group B than in group A (28.7% vs. 14.9%) (P = 0.03). In particular, more local (hyperstimulation or hypertonus) side effects were noted in group B (13.7% vs. 2.3%) (P = 0.01). CONCLUSION: The vaginal administration of 2.0 mg of PGE2 gel seems to be equally effective as 3.0 mg in terms of labor success rate with a significant lower incidence of side effects.

Administration, Intravaginal↗