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T Vidal

Publications and source records attributed to T Vidal.

16 recordsLinked to original sources
PubMed2004

The analysis of handsheets from wheat straw following solid substrate fermentation by Streptomyces cyaneus and soda cooking treatment.

The recent interest in the utilisation of agricultural fibres has promoted research into their potential as raw materials for the pulp and paper industry. In the current study, we report on the effect of biological pretreatment of wheat straw by Streptomyces cyaneus on the performance of the handsheets produced from the treated pulps. The pre-treatment of wheat straw with S. cyaneus had a positive effect on both the burst and tear indexes of the pulps but had a negative impact on tensile index. No significant variation in permeability and in folding endurance was observed. Manipulation of handsheets from wheat straw through biological treatment may therefore result in improved quality traits.

Bioreactors↗
PubMed2003

TCF bleaching of wheat straw pulp using ozone and xylanase. Part A: paper quality assessment.

The XOAZRP TCF sequence was applied to bleach wheat straw pulp. Following each bleaching stage, the properties of the pulp (viz. kappa number, standard viscosity, borohydride viscosity and brightness) and of the resulting effluents were determined. The performance of the reagents was analyzed through the studies of xylanase treatment and crystallinity and scanning electron microscopy of the pulps. Finally, the pulp was refined at 1000 revolutions in a PFI mill and the mechanical properties of the resulting paper were determined and compared with those of paper from a eucalyptus pulp. Despite its shortcomings, wheat straw pulp can be effectively bleached with the proposed TCF sequence.

Conservation of Natural Resources↗
PubMed2003

TCF bleaching of wheat straw pulp using ozone and xylanase. Part B: kinetic studies.

The reaction kinetics of ozone bleaching of wheat straw pulp has been studied for the first time. The results were compared with eucalyptus pulp in order to know that both raw materials have a similar behaviour. Ozone treatments were carried out in a special reactor at low consistency (0.5% o.d.p.). The main variables were consumption of ozone by the pulp and application of a xylanase treatment (X) prior to the oxygen stage (O). The responses measured were kappa number, viscosity and brightness, to give the kinetic expressions for delignification, cellulose degradation and elimination of chromophore groups, along with calculation of selectivity. Cellulose degradation and elimination of lignin and chromophore groups show first-order kinetics in all cases. The kinetics of the enzyme pre-treatment effect shows similar behaviour in both raw materials, although the constants of delignification and elimination of chromophore are higher in straw pulp.

Conservation of Natural Resources↗
PubMed2001

Molecular cloning and characterization of a multidomain endoglucanase from Paenibacillus sp BP-23: evaluation of its performance in pulp refining.

The gene celB encoding an endoglucanase from Paenibacillus sp. BP-23 was cloned and expressed in Escherichia coli. The nucleotide sequence of a 4161 bp DNA fragment containing the celB gene was determined, revealing an open reading frame of 2991 nucleotides that encodes a protein of 106,927 Da. Comparison of the deduced amino acid sequence of endoglucanase B with known beta-glycanase sequences showed that the encoded enzyme is a modular protein and exhibits high homology to enzymes belonging to family 9 cellulases. The celB gene product synthesized in E. coli showed high activity on carboxymethyl cellulose and lichenan while low activity was found on Avicel. Activity was enhanced in the presence of 10 mM Ca2+ and showed its maximum at 53 degrees C and pH 5.5. The effect of the cloned enzyme in modifying the physical properties of pulp and paper from Eucalyptus was tested (CelB treatment). An increase in mechanical strength of paper and a decrease in pulp dewatering properties were found, indicating that CelB treatment can be considered as a biorefining. Treatment with CelB gave rise to an improvement in paper strength similar to that obtained with 1,000 revolutions increase in mechanical refining. Comparison with the performances of recently developed endoglucanase A from the same strain and with a commercial cellulase showed that CelB produced the highest refining effect.

Bacillus↗
PubMed1998

Cloning of a new endoglucanase gene from Bacillus sp. BP-23 and characterisation of the enzyme. Performance in paper manufacture from cereal straw.

The gene ce1A, encoding an endoglucanase from the strain Bacillus sp. BP-23, was cloned and expressed in Escherichia coli. The nucleotide sequence of a 1867-bp DNA fragment containing the ce1A gene was determined, revealing an open reading frame of 1200 nucleotides that encodes a protein of 44,803 Da. The deduced amino acid sequence of the encoded enzyme shows high homology to those of enzymes belonging to subtype 4 of the family-A cellulases. The ce1A gene product synthesized in E. coli showed activity on carboxymethylcellulose and lichenan but no activity was found on Avicel. Activity was enhanced in the presence of 10 mM Mg2+ and Ca2+ and showed its maximum at 40 degrees C and pH 4.0. Study of the performance of Ce1A on paper manufacture from agricultural fibres showed that treatment with the enzyme improved the properties of the pulp and the quality of paper. Ce1A treatment enhanced the physical properties (stretch and tensile index) of paper from wheat straw, while dewatering properties were slightly diminished. Electron-microscope analysis showed that the surface of straw fibres was modified by Ce1A.

Amino Acid Sequence↗
PubMed1998

Specific cellular and humoral immune response in Balb/c mice immunised with an expression genomic library of Trypanosoma cruzi.

An expression genomic library of Trypanosoma cruzi (T. cruzi) constructed using pcDNA3 plasmid was used for the immunisation (25 micrograms) of Balb/c mice. Expression of T. cruzi antigens in the muscle of inoculated mice was detected by indirect immunofluorescence 7 days after immunisation. Specific IgG antibodies were significatively increased (P < 0.05) in animals that were reimmunized with 50 micrograms of the genomic library. An antigen specific lymphoproliferative response was detected in one animal of the group inoculated with one dose of the library.

Animals↗
PubMed1996

[Estimation of costs attributable to nosocomial infection: prolongation of hospitalization and calculation of alternative costs].

BACKGROUND: Nosocomial infection represents a prolongation of hospital stay and an increase of costs. The aim of the study was to estimate attributable costs by means of two methods: calculation of costs resulting from an increase of hospital stay and calculation of costs attributed to services. METHODS: A matched case-control study was carried out with a cohort population. An appropriate control was found for 63 patients with surgical site infection, for 30 patients with respiratory infection and for 55 with urinary infection. The estimation of costs attributable to services includes the case-control pairs with surgical site infection and was performed of the sum of costs of diagnostic and therapeutic services rendered in the care of the surgical site infection. RESULTS: The median of postoperative stay was 21 days for cases with surgical site infection vs 10 days for controls (p < 0.001); the median length of stay was 21.5 days for cases with respiratory infection vs 11.5 days for controls (p < 0.01); and for urinary infection the median length of stay was 21 days for cases vs 15 days for controls (p < 0.01). The surgical site infection cost attributed to extra days was 310,310 pesetas and the surgical site infection cost attributed to service cost was 220,546 pesetas. CONCLUSIONS: Nosocomial infection produces a increase median hospital stay of 7-10 days. In absence of a precise accounting system, the prolongation of hospital stay was considered as the more objective date to estimate the costs.

Adolescent↗
PubMed1996

Incidence of insulin-dependent diabetes mellitus in the IX region of Chile: ethnic differences.

We studied the incidence of insulin-dependent diabetes mellitus (IDDM) among children up to 15 years old of Caucasian and Mapuche origin, in the IX Region of Chile between 1980 and 1993. The Mapuche, or native Chileans, have their own culture, language an distinctive ethnic characteristics. Data were collected according to the methods recommended by the Diabetes Epidemiology Research International Group. We diagnosed IDDM in 47 children, 22 boys and 25 girls. The average annual incidence was 1.27/100,000 inhabitants (95% confidence intervals (C.I.) 0.83-1.71/100,000). The highest incidence along this period was during winter and spring. There was significant difference (P < 0.0016) in the IDDM incidence in Caucasians (1.58/100,000, 95% C.I. 1.11-2.04) compared with Mapuche (0.42/100,000, 95% C.I. 0-0.95). These results show that Mapuche children have less chance of developing diabetes.

Adolescent↗
PubMed1995

Purification and properties of xylanase A from alkali-tolerant Bacillus sp. strain BP-23.

Xylanase A from the recently isolated Bacillus sp. strain BP-23 was purified to homogeneity. The enzyme shows a molecular mass of 32 kDa and an isoelectric point of 9.3. Optimum temperature and pH for xylanase activity were 50 degrees C and 5.5 respectively. Xylanase A was completely inhibited by N-bromosuccinimide. The main products of birchwood xylan hydrolysis were xylotetraose and xylobiose. The enzyme was shown to facilitate chemical bleaching of pulp, generating savings of 38% in terms of chlorine dioxide consumption. The amino-terminal sequence of xylanase A has a conserved sequence of five amino acids found in xylanases from family F.

Alkalies↗
PubMed1994

Late recurrent metastasis in Wilms' tumour.

Recurrence of Wilms' tumour after 5 years of disease-free survival is rare. We present the case of a 26-year-old man who had been diagnosed of Wilms' tumour at the age of 6 years treated by surgery, chemotherapy, and radiotherapy and who remained disease free for 8 years, after which lung metastases were detected. Second complete remission was attained with surgery and chemotherapy and 20 years after initial diagnosis he again presented with lung metastases, similarly achieving complete remission with surgery and second-line chemotherapy. The clinical and biological aspects of late metastasis in this neoplasm are discussed.

Adult↗
PubMed1992

[Bilateral Leydig cell tumor].

A 7 year old boy presented with bilateral nodular testicular swelling, adult penis development and scrotal aspect. Laboratory studies revealed a bone age of 13 years, increased testosterone, estradiol, DHEA-S, and 17 ketosteroids levels. The GnRH test revealed puberal findings. Biopsy was consistent with Leydig cell tumor with presence of Reinke crystals. After enucleation of the tumor signs of necrosis and malignancy were shown. Orchiectomy will follow as chemotherapy and radiotherapy have been reported to be without value.

Child↗
PubMed1991

[Cryptosporidium: outbreak at a nutrition rehabilitation center, Temuco].

Cryptosporidiosis was observed in 23 undernourished infants of a nutritional center in Temuco. This represents a 34% incidence rate for the period (march to may 1990). Liquid stools (91%), vomiting (39%), resistance to feeding (74%), respiratory symptoms (61%) and weight loss (mean 25 g per day) were the main clinical manifestations. Only 9 patients received specific therapy and all showed clinical improvement and normalization of stool examinations within the study period.

Adult↗
PubMed1989

[The visual field of patients with pituitary adenoma surgically treated].

The authors report the evolution of 72 patient's visual field operated for one pituitary adenoma. They specify the constant amelioration of this investigation in chromophobic adenomas. The stability in prolactinic adenomas or somatotropic. Allowing the supervision of the visual case, at these patients, the visual field does not seem useful in the diagnosis of the tumors recurrence.

Adenoma↗