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Biomedical subjects

A Ballester

Publications and source records attributed to A Ballester.

At least 19 recordsLinked to original sources
PubMed2006

Biosorption of heavy metals by activated sludge and their desorption characteristics.

The biosorption of different metals (Cu2+, Cd2+, Zn2+, Ni2+ and Pb2+) was investigated using activated sludge. The optimum pH was 4 for Cd, Cu and Pb sorption and 5 for Ni and Zn. Biomass metal uptake clearly competed with protons present in the aqueous medium, making pH an important variable in the process. Protons consumed by biomass in control tests versus protons exchange in biosorption tests confirmed a maximum exchange between metal cations and protons at pH 2. The study of the influence of biomass concentration revealed that the amount of protons released from biomass increased with biomass concentration. This would confirm the hypothesis of ion exchange between both types of ions. The application of the Langmuir and Freundlich models showed a better fitting of experimental data to the first model. The maximum sorption uptake of the studied metals by the activated sludge showed the following decreasing order: Pb>Cu>CdZn>Ni. Desorption experiments showed that HCl was a good eluent for the five metals tested, particularly at low pH values (1 and 2). At pH 3 or 4 the desorption yield was significantly lower. However, its use did not allow the reuse of biomass in subsequent loading and unloading cycles. EDTA was also a good desorption agent, achieving the total recovery for the five metals tested at a concentration of 1mM, with the advantage that biomass could be reused for three sorption-desorption cycles.

Adsorption↗
PubMed2006

Microbial activity in weathering columns.

The aim of the present work was to evaluate the metabolic activity of the microbial population associated with a pyritic tailing after a column-weathering test. For this purpose, a column 150cm high and 15cm diameter was used. The solid was a tailing with 63.4% pyrite and with minor amounts of Cu, Pb and Zn sulfides (1.4, 0.5 and 0.8%, respectively). The column model was the habitual one for weathering tests: distilled water was added at the top of the column; the water flowed down through tailings and finally was collected at the bottom for chemical and microbiological analysis. Weathering was maintained for 36 weeks. The results showed a significant presence of microbial life that was distributed selectively over the column: sulfur- and iron-oxidizing aerobic bacteria were in the more oxygenated zone; anaerobic sulfur-reducing bacteria were isolated from the samples taken from the anoxic part of the column. Activity testing showed that (oxidizing and reducing) bacteria populations were active at the end of the weathering test. The quality of the water draining from the column was thus the final product of biological oxidation and reduction promoted by the bacteria consortia.

Bacteria, Aerobic↗
PubMed2006

Plant regeneration through somatic embryogenesis from tissues of mature oak trees: true-to-type conformity of plantlets by RAPD analysis.

Somatic embryogenesis was induced in expanding leaf explants excised from epicormic shoots forced from branch segments taken at four different times of year from a mature oak (Quercus robur L.). Branch segments 2-4 cm in diameter produced most shoots when collected in March. Somatic embryos were induced on explants derived from branches of all collection dates, although collection in November seemed to afford the best results. Germination and conversion ability of embryos of embryogenic lines derived from six oak trees depended heavily on genotype, conversion rates ranging from 0 to 70%. RAPD analyses found no evidence of genetic variation either within or between the embryogenic lines established from three of these trees, or between these lines and the trees of origin, or between somatic embryo derived plantlets and the trees of origin. The embryogenic system used in this study appears to be suitable for true-to-type clonal propagation of mature oak genotypes.

Culture Media↗
PubMed2005

Seroprevalence of varicella among children and adolescents in Valencia, Spain. Reliability of the parent's reported history and the medical file for identification of potential candidates for vaccination.

This study assessed the seroprevalence of varicella antibodies in children and adolescents in Spain and evaluated the reliability of two methods for detecting susceptible individuals: (1) parental-reported history of varicella and (2) medically-documented histories maintained by the pediatrician. A total of 186 children (6 to 15 years of age) were recruited in 13 pediatric offices of Valencia, Spain. A brief case report form was completed including previous history of varicella referred by the parents, and a 5 mL blood sample was obtained. The pediatrician medical file was reviewed for antecedent of varicella. The overall prevalence of varicella antibodies was 84% and 88% in the 6-9 years and 10-15 years age brackets, respectively. The predictive value of a negative history of varicella disease was 48% by parental recall (52% "false negative"), and only 26% by medical record (74% "false negative"). However, the positive predictive value of a positive parental reported history or a positive medically-documented history was 95%. The most effective strategy for varicella vaccination of older children and adolescents in Spain will be to immunize those individuals with a lack of positive (unknown or negative) history of disease.

Adolescent↗
PubMed2005

Gold and silver uptake and nanoprecipitation on calcium alginate beads.

Calcium alginate beads were investigated for their biosorption performance in the removal of gold and silver from aqueous solutions. It was found that uptake capacities were significantly affected by the solution pH, with optimum pH values of 2 and 4 for gold and silver, respectively. Kinetic and isotherm experiments were carried out at the optimum pH. The maximum uptake capacities were 290 mg/g for Au and 52 mg/g for Ag. FTIR analysis indicated that both carboxylic and hydroxylic functional groups in alginate beads are involved in the metal binding and later reduction of gold (+3) and silver (+1) to gold (0) and silver (0). SEM and X-ray diffraction confirmed the formation of gold and silver nanoparticles.

Adsorption↗
PubMed2005

Factors affecting the transformation of a pyritic tailing: scaled-up column tests.

Two different methods for predicting the quality of the water draining from a pyritic tailing are compared; for this, a static test (ABA test) and a kinetic test in large columns were chosen. The different results obtained in the two experimental set-ups show the necessity of being careful in selecting both the adequate predictive method and the conclusions and extrapolations derived from them. The tailing chosen for the weathering tests (previously tested in shake flasks and in small weathering columns) was a pyritic residue produced in a flotation plant of complex polymetallic sulphides (Huelva, Spain). The ABA test was a modification of the conventional ABA test reported in bibliography. The modification consisted in the soft conditions employed in the digestion phase. For column tests, two identical methacrylate columns (150 cm high and 15 cm diameter) were used to study the chemical and microbiological processes controlling the leaching of pyrite. The results obtained in the two tests were very different. The static test predicted a strong potential acidity for the tailing. On the contrary, pH value in the effluents draining from the columns reached values of only 5 units, being the concentration of metals (<600 mg/L) and sulphate ions (<17,000 mg/L) very small and far from the values of a typical acid mine drainage. In consequence, the static test may oversize the potential acidity of the tailing; whereas large columns may be saturated in water, displacing the oxygen and inhibiting the microbial activity necessary to catalyse mineral oxidation.

Environmental Monitoring↗
PubMed2005

Prevalence of silent fecal and urinary incontinence in women from the town of Teruel.

OBJECTIVES: To study the prevalence of fecal (FI) and urinary incontinence (UI) in women from Teruel (Spain), as well as the clinical conditions associated with these disorders. METHODS: We studied prospectively women with an age range of 20-64 years who were randomly selected from the population seen in a primary care center because of medical disorders not related to incontinence. Patients with functional or cognitive impairment were excluded. Medical and obstetric antecedents, as well as the type and frequency of incontinence symptoms were collected in a questionnaire. RESULTS: Out of 115 women, 103 completed the study (mean age: 41+/-12 years range 20-64). UI was present in 34.9% (stress 33%, urge 14%, mixed 47%), FI in 14 (13.6%) (flatus 57%, liquid stools 43%), and 10 (9.7%) displayed both disorders. Age > 42 years and body mass index more or equal of 25 were associated with FI and UI; pregnancy was only associated with UI, but the group of women with more or equal of 2 vaginal deliveries showed a higher frequency of FI (p < 0.05, Chi squared test). In the multivariate analysis, only the presence of UI was associated with FI (OR 6.0; CI 95% 1.7-21). Association of FI and UI was more frequent in women older than 42 years (OR 16.7, CI 95% 1.9-141). No statistical differences were found when smoking, exercise, and type of childbirth were compared between the presence/absence of FI or UI. CONCLUSIONS: Urinary and fecal incontinence are frequent in women, and the coexistence of both disorders is not uncommon. Age, overweight and parity are associated with the presence of fecal and/or urinary incontinence.

Adult↗
PubMed2004

Agrobacterium-mediated transformation of European chestnut embryogenic cultures.

An innovative and efficient genetic transformation protocol for European chestnut is described in which embryogenic cultures are used as the target material. When somatic embryos at the globular or early-torpedo stages were cocultured for 4 days with Agrobacterium tumefaciens strain EHA105 harbouring the pUbiGUSINT plasmid containing marker genes, a transformation efficiency of 25% was recorded. Murashige and Skoog culture medium containing 150 mg/l of kanamycin was used as the selection medium. The addition of acetosyringone was detrimental to the transformation efficiency. Transformation was confirmed by a histochemical beta-glucuronidase (GUS ) assay, PCR and Southern blot analyses for the uidA (GUS) and nptII (neomycin phosphotransferase II) genes. At present, 93 GUS-positive chestnut embryogenic lines are being maintained in culture. Low germination rates (6.3%) were recorded for the transformed somatic embryos. The presence of the transferred genes in leaves and shoots derived from the germinated embryos was also verified by the GUS assay and PCR analysis.

Acetophenones↗
PubMed2003

Proliferation, maturation and germination of Castanea sativa Mill. Somatic embryos originated from leaf explants.

Experiments were performed to determine the influence of proliferation medium on the maintenance of embryogenic competence and on repetitive embryogenesis in Castanea sativa Mill. somatic embryos derived from leaf explants. Somatic embryo proliferation was carried out by both direct secondary embryogenesis and by the culture of nodular callus tissue originated from cotyledons of somatic embryos. Both systems led to the production of cotyledonary somatic embryos on Murashige and Skoog proliferation medium supplemented with 0.1 mg l-1 benzyladenine and 0.1 mg l-1 naphthaleneacetic acid. Carbon source and concentration had a marked influence on maturation and subsequent germination ability of chestnut somatic embryos. Plantlet conversion was achieved in embryos matured on media with 6 % sucrose, and on 3 or 6 % maltose, whereas mean shoot length, root length and leaf number of produced plants were not significantly affected by these maturation media. Overall, the best results were obtained with 3 % maltose-matured somatic embryos, giving rise to 6 % plant recovery in addition to 33 % of embryos exhibiting only shoot development. The application of a 2-month cold treatment at 4 degrees C to somatic embryos matured on medium with 3 % maltose was necessary for achieving plant conversion, while partial desiccation did not appear to influence this response. A total of 39 % of embryos eventually produced plants either through conversion to plantlets or indirectly through rooting of shoots. Shoots formed by somatic embryos could be excised, multiplied and rooted following the micropropagation procedures previously developed for chestnut.

Culture Media↗
PubMed2003

Cryopreservation of embryogenic cultures of Quercus robur using desiccation and vitrification procedures.

Oak embryogenic cultures are generally maintained by repetitive embryogenesis. To facilitate management of embryogenic lines and limit the risks of somaclonal variation and contamination a cryopreservation protocol should be developed. In this work we investigated the ability of several pre-treatments to enable 4-6mg clumps (1.0-1.5mm) of globular-heart stage somatic embryos of Quercus robur to withstand freezing in liquid nitrogen. In the best of the two embryogenic culture lines used, 56% of clumps resumed embryogenesis after cooling when they had been pre-treated by successive pre-culture on 0.3 and 0.7M sucrose supplemented media followed by desiccation in the air flow of a laminar flow cabinet to water contents of 24-34%. In both lines, embryogenesis resumption rates of about 70% were achieved by pre-culture on 0.3M sucrose medium followed by application of a vitrification solution (PVS2) for 60-90min prior to rapid plunging in liquid nitrogen.

Cell Line↗
PubMed2003

Developmental stages during the rooting of in-vitro-cultured Quercus robur shoots from material of juvenile and mature origin.

In-vitro-cultured shoots of clones initiated from shoots of the basal parts (BS) and the crown (C) of two mature Quercus robur L. trees were subjected to rooting experiments to relate rooting with shoot topophysical origin. The BS shoots exhibited morphologically juvenile characteristics and rooted more easily after indole-3-butyric acid (IBA) treatment than C shoots. When naphthylphthalamic acid (NPA) was applied to BS shoots, rooting capacity decreased and root emergence was delayed at least 2 days compared with shoots treated with IBA only. During the first days of the rooting process, endogenous indole-3-acetic acid (IAA) concentration was higher in C shoots than in BS shoots, regardless of whether the shoots were treated with NPA. Mitotic figures were observed in cells from the basal part of both BS and C shoots 24 h after IBA treatment. After 4 days of IBA treatment, the occurrence of histological events differed between BS shoots and C shoots. Cells of BS shoots became meristematic, giving rise to meristemoids and root primordia, whereas no differentiation of root meristemoids occurred in cells of C shoots. Thus, although adult oak material (C shoots) is capable of responding to the initial stimulus of auxin during the adventitious rooting process, the endogenous IAA concentration is not the factor limiting rooting in adult material.

Indoleacetic Acids↗
PubMed2002

Somatic embryogenesis in elm.

We show that isolated zygotic embryos of Ulmus minor and U. glabra can produce embryogenic cultures provided they are isolated from immature seeds before storage proteins begin to accumulate. Rates of somatic embryogenesis were highest among zygotic embryos collected 6 weeks post-anthesis when they were at the midcotyledonary stage, were about 5 mm long and had a fresh weight of approx. 10 mg. At this time, induction was even possible in Murashige and Skoog basal medium with no plant growth regulators, but addition of 2,4-dichlorophenoxyacetic acid was necessary at earlier stages of zygotic development. In medium supplemented with benzyladenine (BA) only, no embryogenic induction was observed. The formation of callus was an essential step not only for the induction of embryogenic masses, but also for the maintenance of embryogenic competence through successive subculture of callus on induction media supplemented with 0.1 mg l(-1) BA. Nine embryogenic U. minor lines and 24 U. glabra lines have been maintained in this way for 3 years. However, conversion into plantlets has occurred only rarely.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2001

Heterologous expression of the transcriptional regulator escargot inhibits megakaryocytic endomitosis.

Certain cell types escape the strict mechanisms imposed on the majority of somatic cells to ensure the faithful inheritance of parental DNA content. This is the case in many embryonic tissues and certain adult cells such as mammalian hepatocytes and megakaryocytes. Megakaryocytic endomitosis is characterized by repeated S phases followed by abortive mitoses, resulting in mononucleated polyploid cells. Several cell cycle regulators have been proposed to play an active role in megakaryocytic polyploidization; however, little is known about upstream factors that could control endomitosis. Here we show that ectopic expression of the transcriptional repressor escargot interferes with the establishment of megakaryocytic endomitosis. Phorbol ester-induced polyploidization was inhibited in stably transfected megakaryoblastic HEL cells constitutively expressing escargot. Analysis of the expression and activity of different cell cycle factors revealed that Escargot affects the G(1)/S transition by influencing Cdk2 activity and cyclin A transcription. Nuclear proteins that specifically bind the Escargot-binding element were detected in endomitotic and non-endomitotic megakaryoblastic cells, but down-regulation occurred only during differentiation of cells that become polyploid. As Escargot was originally implicated in ploidy maintenance of Drosophila embryonic and larval cells, our results suggest that polyploidization in megakaryocytes might respond to mechanisms conserved from early development to adult cells that need to escape normal control of the diploid state.

CDC2-CDC28 Kinases↗
PubMed2001

Comparative study on the selective chalcopyrite bioleaching of a molybdenite concentrate with mesophilic and thermophilic bacteria.

This study evaluates different bioleaching treatments of a molybdenite concentrate using mesophilic and thermophilic bacterial cultures. Further studies on the chemical leaching and the electrochemical behavior of the MoS(2) concentrate were carried out. Bioleaching tests showed a progressive removal of chalcopyrite from the molybdenite concentrate with an increase in temperature. Chemical leaching tests support the idea of an indirect attack of the concentrate. Electrochemical tests indicate that chalcopyrite dissolution is favored when molybdenite is present. Therefore, this type of bioleaching treatment could be applied to purify molybdenite flotation concentrates by selectively dissolving chalcopyrite.

Bacteria↗
PubMed2000

COT kinase proto-oncogene expression in T cells: implication of the JNK/SAPK signal transduction pathway in COT promoter activation.

COT/Tpl-2 proto-oncogene encodes a serine/threonine kinase implicated in cellular activation. In this study we have identified the human COT gene promoter region and three different human COT transcripts. These transcripts, with the same initiation site, display heterogeneity in their 5' untranslated regions and in their subcellular localization. Activation of Jurkat T cells with either calcium ionophore or alphaCD3 and a phorbol ester increases the levels of the different COT transcripts. Analysis of the 5' flanking region of the human COT gene reveals a unique transcription initiation site and a TATA element 20 nucleotides upstream. Transient expression of COT promoter constructs containing a reporter gene indicates that the transcriptional activity of the 5' flanking region of the COT gene is regulated by T cell-activating signals. Cotransfection of a dominant negative version of SEK-2 abolishes the inducible transcriptional activity of COT promoter, indicating that the inducible expression of the COT gene by T cell activating signals is mediated by the JNK/SAPK signal transduction pathway. All these data indicate stringent regulation of COT kinase proto-oncogene expression.

5' Untranslated Regions↗
PubMed2000

Lack of association of serum lipoprotein (a) levels with type-2 diabetes mellitus in patients with angiographically defined coronary artery disease.

Multiple studies have demonstrated that elevated serum lipoprotein (a) [Lp(a)] levels are independent predictors for coronary artery disease (CAD) in subjects without diabetes mellitus (DM). However, their contribution in patients with DM is controversial and still requires clarification. We determined serum Lp(a) levels in 355 consecutive Caucasian patients (271 men and 84 women) with angiographically documented CAD, and in 100 control subjects (58 men and 42 women) who were clinically free of cardiovascular disease. In addition, the association of serum Lp(a) levels with type-2 DM in patients with CAD was investigated after reassigning patients according to the diagnosis of type-2 DM (61 men and 40 women with type-2 DM and 210 men and 44 women without). No gender differences in Lp(a) levels were observed between men and women (patients and control subjects). Patients with CAD had higher Lp(a) levels than the control subjects (33 (14-74) vs. 13 (9-29) mg/dl, P<0.001). Elevated Lp(a) levels (defined as >90th percentile of controls) were significantly more prevalent in men and women with CAD (35% and 28%, respectively) than in control subjects (13% and 10%, respectively). Serum Lp(a) levels correlated with LDL cholesterol (r=0.22, P<0.001) and apo B levels (r=0.18, P<0.03) in patients and control subjects. Stepwise discriminant analysis revealed that Lp(a) was an independent risk factor for the presence of CAD, independent of smoking, hypertension, type-2 DM, LDL and HDL cholesterol or apo A1 and B levels. When patients were studied according to the spread of CAD (evaluated as the number of narrowed vessels), no differences in serum Lp(a) levels were observed, nor was there a higher prevalence of elevated Lp(a) levels. Finally, when patients were re-assigned according to the diagnosis of type-2 DM, no effect of apo B and LDL-C levels on Lp(a) was found (r=0.06, P=n.s. and 40.14, P=n.s., respectively) and serum Lp(a) levels neither associated nor contributed to the extent of CAD. Our results showed that serum Lp(a) levels are increased in patients with angiographically documented CAD, but there were no significant differences between diabetic and non-diabetic patients, which indicates that elevated Lp(a) levels are specifically associated with CAD but not with type-2 DM.

Adult↗
PubMed2000

Ectopic expression of cyclin E allows non-endomitotic megakaryoblastic K562 cells to establish re-replication cycles.

Megakaryocytes become polyploid by entering a truncated cell cycle, consisting of alternate S phases and abortive mitoses. We have investigated the regulation of the G1/S transition by comparing two megakaryoblastic cell lines, HEL and K562, which respectively do or do not become polyploid in response to phorbol esters. A pronounced downregulation of cyclin A, and to a lesser extent of cyclin E, occurred in K562 cells during the first 24 h after TPA treatment, in contrast with re-replicating HEL cells, in which both cyclins were present in individual G2/M cells. Transactivation experiments suggested that the absence of cyclin A in differentiated K562 cells could be due to a TPA-mediated inhibition of its transcription. To investigate the potential role of cyclin E in the establishment of re-replication cycles, we isolated K562 clones constitutively expressing cyclin E. The resulting clones, and also K562 cells transiently expressing cyclin E, entered re-replication cycles when treated with TPA. The transcriptional activity of the cyclin A promoter was not inhibited after TPA treatment, and although the levels of cyclin A fluctuated during further re-replication cycles, they never decreased below S phase levels. We conclude that the presence of cyclin E in megakaryoblastic G2/M cells determines cyclin A expression and allows the entrance into an extra S phase.

Bone Marrow Cells↗