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Biomedical subjects

A I Fernández

Publications and source records attributed to A I Fernández.

15 recordsLinked to original sources
PubMed2005

Optimization of phosphate removal in anodizing aluminium wastewater.

The wastewater produced after brightening and anodizing aluminium has high concentrations of phosphates and sulphates. The addition of MgO in a first physico-chemical wastewater treatment step makes the selective recovery of phosphates in the form of magnesium phosphates feasible, which may be reused as fertilizer. The proposed wastewater treatment process allows manufacturers to reduce more than 70% of the volume of the precipitate in the sedimentation reactor and more than 50% of the weight of the final disposal sludge. In this study, the use of an alternative low-grade MgO (LG-MgO) as a source of magnesium, which is cheaper than pure MgO, is investigated. The phosphate concentration and pH of the treated wastewater is controlled by the formation and precipitation of newberyite or bobierrite as a function of the magnesium source added. According to experimental data, a reaction mechanism is proposed. Although LG-MgO reacts more slowly than pure MgO and it is necessary to add 3-4 times the stoichiometric amount, this procedure has considerable economic and technical advantages.

Aluminum↗
PubMed2005

Optimizing the APC residue washing process to minimize the release of chloride and heavy metals.

An optimization of the air pollution control (APC) residue washing process was carried out to minimize the release of chloride and heavy metals. Taking into account economic parameters such as the consumption of water and reaction time, the best relation found was a S/L ratio of 1/3 during 1 h. At a laboratory scale and according to the values obtained for chloride and heavy metals, the APC residue is classified as non-special according to Catalonian Regulations (Spain). Moreover, the pH of the solution, when MgSO(4) is added during the washing process, may be controlled by the formation of gypsum. In these conditions, the concentration of heavy metals will decrease as a consequence of the formation of their respective insoluble hydroxides. Therefore, the counter-current batch washing process with the addition of small amounts of MgSO(4) is revealed as an economically feasible treatment of the APC residue. This washed residue is ready to be used as secondary material or to be landfilled safely.

Air Pollutants↗
PubMed2004

Low-grade MgO used to stabilize heavy metals in highly contaminated soils.

Low-grade MgO may be an economically feasible alternative in the stabilization of heavy metals from heavily contaminated soils. The use of MgO is described acting as a buffering agent within the pH 9-11 range, minimizing heavy metals solubility and avoiding the redissolution that occurs when lime is used. The effectiveness of LG-MgO has been studied as stabilizer agent of heavily polluted soils mainly contaminated by the flue-dust of the pyrite roasting. The use of LG-MgO as a reactive medium ensures that significant rates of metal fixation, greater than 80%, are achieved. The heavy metals leachate from the stabilized soil samples show a concentration lower than the limit set to classify the waste as non-special residue. Regardless of the quantity of stabilizer employed (greater than 10%), LG-MgO provides an alkali reservoir that allows guaranteeing long-term stabilization without varying the pH conditions.

Environmental Pollution↗
PubMed2003

Removal of ammonium and phosphates from wastewater resulting from the process of cochineal extraction using MgO-containing by-product.

The wastewater produced by the cochineal extract process to obtain the carminic acid colouring pigment (carmin red E120) has high concentrations of phosphates and ammonium. It is known that both ions can be precipitated with magnesium in the form of struvite, MgNH(4)PO(4), or ammonium magnesium phosphate (MAP) compounds. In this study, the use of an alternative MgO-containing by-product is investigated. The optimal pH, reaction time and solid/liquid ratio have been studied. It has been found that the low-grade MgO needed is greater than the stoichiometric value for the full removal of ammonium and phosphate as MAP compounds. Although the low-grade MgO (LG-MgO) reacts slower than pure MgO, it has considerable economic advantages. A batch process has been proposed for the removal of ammonium and phosphates from wastewater obtained in cochineal extracts processing, previously to biological treatment to diminish the COD.

Antacids↗
PubMed2003

Short-term natural weathering of MSWI bottom ash as a function of particle size.

The chemical and material composition of MSWI bottom ash depends on the particle size; this suggests that the mechanisms and kinetics of natural weathering are also a function of particle size. This paper reports the effects of short-term natural weathering on the leaching of heavy metals (mainly Pb, Cu and Zn) from MSWI bottom ash. Initial concentrations of heavy metals were higher for the smallest particle size fractions, but these levels fell dramatically during the first 50 days of weathering before levelling off. The main differences between size fractions were in the pH and the solubility of calcium and aluminium. For the initial stages of weathering and small size fractions, portlandite solubility seemed to control the pH. In contrast, for fractions bigger than 6 mm, the formation of ettringite was the reaction controlling the pH and the solubility of sulphates, aluminium and calcium.

Carbon↗
PubMed2000

Short-term natural weathering of MSWI bottom ash.

The release of heavy metals from MSWI bottom ash has been the key concern in the management of this material. The leaching distribution values obtained from 100 freshly quenched bottom ash samples, according to the German DIN 38414-S4 procedure test, showed the release of lead, zinc and copper to be the main hazards associated with bottom ash utilisation as a secondary building material. Currently, natural weathering of MSWI bottom ash, for an estimated period of 1-3 months, is the most economic treatment available to ensure the eventual utilisation of this material. The leaching of natural weathered bottom ash in the short-term (up to 9 months) was studied. The most significant changes in the bottom ash were found to occur in the first 90 days. At pH values greater than 12, lead, zinc and copper were the main heavy metals to be released from the MSWI freshly quenched bottom ash samples studied. Natural weathering for a period of about 90 days reduced the leaching of heavy metals, stabilising the bottom ash pH to minimise the solubility of metal hydroxides, and enabled the residue to be used as secondary building material. The profile of the pH neutralisation curve is similar to that described by carbonates, which would suggest that the reaction is controlled by CO(2). The formation of insoluble oxides as well as carbonates control the immobilisation of certain heavy metals, e.g. lead and zinc. The leaching of aluminium increases during this short natural weathering stage due to elemental metal oxidation. Aluminium solubility is controlled by the precipitation of gibbsite or other aluminium-sulphate neoformations. The latter may contribute to the immobilisation of heavy metals.

Air Pollutants↗
PubMed1998

Serological and immunohistochemical study of African swine fever in wild boar in Spain.

A serological and immunohistochemical study of African swine fever was carried out in wild boar killed in seven municipalities in the north of the province of Córdoba during two hunting seasons (1991-92 and 1992-93), when the area was affected by the disease. Fourteen of 147 wild boar analysed by ELISA and immunoblotting had antibodies to African swine fever virus. The immunohistochemical study revealed that four cases (two seropositive and two seronegative) showed immunoreactivity to the anti-VP73 monoclonal antibody. Two of the VP73+ wild boar had severe generalised haemorrhages consistent with the acute from of the disease, and another had lesions consistent with subacute African swine fever, but none of the remaining 144 animals had gross or microscopic changes suggestive of the disease. These results indicate that wild boar can suffer from African swine fever without showing clinical signs. The disease in wild boar was associated with the disease in domestic pigs. Thus, no African swine fever-positive boar were found either in one municipality with no out-breaks in domestic pigs or in three municipalities with only one outbreak in pigs during the hunting seasons and during the previous year. These results suggest that European wild boar do not play an important role as carriers of the virus of African swine fever.

African Swine Fever↗
PubMed1998

Partial contribution of polyamines to the relaxant effect of 17 alpha-estradiol in rat uterine smooth muscle.

1. The effects of 17 alpha-estradiol on KCl (60 mM), CaCl2 (30 microM to 10 mM) and vanadate (0.3 mM)-induced contractions in rat uterus have been assayed. Furthermore, the effect of 17 alpha-estradiol on calmodulin-stimulated cAMP-phosphodiesterase activity was also studied. 2. 17 alpha-estradiol relaxed the tonic contraction induced by KCl (60 mM) in a concentration-dependent way (IC50, 8.3 +/- 0.7 microM), and CaCl2 (0.1 to 10 mM) counteracted it. 3. CaCl2 (30 microM to 10 mM) produced concentration-dependent contraction of rat uterus in a calcium-free medium supplemented with 60 mM of KCl (EC50: 0.2 +/- 0.01 mM). 17 alpha-estradiol (8 microM) antagonized the contraction induced by CaCl2, increasing the EC50 value up to 0.7 +/- 0.1 mM (P < 0.01). 4. 17 alpha-estradiol (0.1 to 1 mM) relaxed in a concentration-dependent way the tonic contraction induced by vanadate in rat uterus incubated in a calcium-free medium and EDTA supplemented. The maximal relaxation achieved with 1 mM of 17 alpha-estradiol was 52.2 +/- 2.8%. 5. 17 alpha-estradiol (1 to 100 microM) did not modify the basal activity of cAMP-phosphodiesterase but inhibited the calcium plus calmodulin stimulated activity. The maximal inhibition achieved was 43 +/- 5.4%. 6. The relaxing effect of 17 alpha-estradiol on KCl (60 mM)-induced tonic contraction was unmodified with the antioestrogen tamoxifen (0.1 and 1 microM), the inhibitor of tirosine kinase (genistein, 10 microM) and the cAMP-dependent protein kinase inhibitor (Rp-adenosine 3',5'-monophosphothioate, triethylamine salt, 100 microM). However, the effect was antagonized with the inhibitor of transcription (actinomycin D, 5 micrograms/ml,), the inhibitor of protein synthesis (cycloheximide, 10 and 100 micrograms/ml), and the inhibitor of ornithine decarboxilase (alpha-difluoromethyl-ornithine, 10 mM). 7. Our results suggest that polyamines contribute to the relaxant effect of 17 alpha-estradiol in rat uterine smooth muscle behaving, presumably, as mediators of the transcriptional component involved in the effect of 17 alpha-estradiol.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1995

Extracellular and intracellular effects of polyamines on smooth muscle contractions.

The natural polyamines spermine, spermidine and putrescine, and their metabolic products N1-acetylspermine (N-AS) and 5'-deoxi-5'-methyl-thioadenosine (DMT), but not N1-acetylspermidine nor N-acetylputrescine, relax the KCl-induced contraction in rat uterus in a dose-dependent way. This relaxing effect is counteracted by CaCl2 (0.1-6 mM) but not by Bay K 8644. Spermine, N-AS and DMT also inhibit the contraction induced by methacholine and PGF2 alpha. Spermine, DMT and N-AS relax the vanadate-induced contraction in uterus incubated in calcium-free solution plus EDTA. However, in the vanadate contraction, the EC50s are higher than those obtained with other contracturants. These results suggest that polyamines inhibit smooth muscle contraction by action at plasma membrane level decreasing the influx of calcium. However, intracellular actions of polyamines could also be involved in their effects.

Animals↗
PubMed1995

Influence of hormonal status in relaxant effect of diethylstilbestrol and nifedipine on isolated rat uterus contraction.

1. The effects of diethylstilbestrol (DES, 10(-7)-10(-5) M) and nifedipine (10(-10)-10(-7) M) on KCl (60 mM)-induced tonic contraction in the uterus of ovariectomized and 17 beta-estradiol (0.1 mg/kg/day, s.c.)-, 17 alpha-estradiol (0.1 mg/kg/day, s.c.)-, or progesterone (2 mg/kg/day, s.c.)-treated rats have been assayed. 2. The dose-dependent relaxation produced by nifedipine in ovariectomized rats (EC50 = 5.59 +/- 1.25 x 10(-9) M) is potentiated in uterus of rats treated with 17 beta-estradiol and progesterone (EC50 = 0.59 +/- 0.1 and 0.49 +/- 0.1 x 10(-9) M, respectively) but not in the 17 alpha-estradiol-treated rats (3.01 +/- 0.6 x 10(-9) M). 3. The relaxation produced by DES on ovariectomized rats (EC50 = 0.84 +/- 0.14 x 10(-6) M) is reduced when the rats are treated with 17 beta-estradiol (EC50 = 2.22 +/- 0.2 x 10(-6)M) or progesterone (EC50 = 1.24 +/- 0.08 x 10(-6) M), but unmodified by 17 alpha-estradiol (EC50 = 0.58 +/- 0.01 x 10(-6) M). 4. The nifedipine-induced relaxation is reversed with Bay K 8644 (10(-10)-10(-6) M) in all experimental conditions. However, Bay K 8644 counteracted the relaxation of DES at 45.7% on ovariectomized rats but this was lower than 30% in the other groups. 5. Our results suggest that in ovariectomized rats the effects of both nifedipine and DES are similar, but 17 beta-estradiol and progesterone produce a contrary effect on the relaxation induced by nifedipine and DES (by increasing the nifedipine and decreasing the DES effects).(ABSTRACT TRUNCATED AT 250 WORDS)

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1994

Progesterone and pregnanolone derivatives relaxing effect on smooth muscle.

1. The effect of gestagens, 5 alpha-hydroxyprogesterone (10(-6) x 10(-5) M), 5 beta-hydroxyprogesterone (10(-6)-3 x 10(-5) M), progesterone (6 x 10(-6)-10(-4) M), pregnanolone (10(-6)-10(-5) M), allopregnanolone (10(-6)-10(-4) M) and epipregnanolone (10(-6)-6 x 10(-5) M) on rat uterine contractions induced by KCl (60 mM), has been assayed. 2. All drugs assayed relaxed the tonic-contraction induced by KCl in a concentration-dependent way. The respectives IC50 were 31.3 +/- 4.1 x 10(-6) M (progesterone), 8.9 +/- 0.8 x 10(-6) M (5 alpha-hydroxyprogesterone), 3.8 +/- 0.3 x 10(-6) M (5 beta-hydroxyprogesterone), 3.1 +/- 0.1 x 10(-6) M (pregnanolone), 21.2 +/- 3.1 x 10(-6) M (allopregnanolone) and 6.3 +/- 1.3 x 10(-6) M (epipregnanolone). This relaxing effect was partially or totally counteracted by CaCl2 (1-10 mM) 3. Cycloheximide (10 micrograms/ml) significantly shifted to the right the effect of allopregnanolone but not the effect of the other drugs. Actinomycin D (5 micrograms/ml) did not modify the effect of allopregnanolone. 4. Our results suggest that the relaxing effect of gestagens in the rat uterus could be related to inhibition on calcium influx and mainly occur through non-genomic mechanisms.

Animals↗
PubMed1994

[Application of immunologic methods to the analysis of bio-leaching bacteria].

Pure cultures of Thiobacillus ferrooxidans and mixed cultures of Thiobacillus ferrooxidans and Leptospirillum ferrooxidans isolated from the Matahambre mine (Cuba) were used to fit immunodiffusion and immunoelectron microscopy to the study of iron oxidizing bacteria. The possibilities, advantages and limits of those techniques have been studied from both the identification and the serological characterization points of view. Finally, the efficiency of these methods was tested by applying them to the identification of microorganisms from acidic waters from the mine.

Animals↗
PubMed1992

Thiobacillus ferrooxidans detection using immunoelectron microscopy.

A specific, fast and very sensitive immunoelectron microscopy method was developed to morphologically and serologically distinguish different cultures of iron oxidizers. Bacteria isolated from the acidic waters of "Matahambre" and "Mina Delita" mines (Cuba) were characterized. An antiserum specific to Thiobacillus ferrooxidans did not react with other bacteria also present in the acidic waters of mine drainage. Our results suggest the occurrence of some strains of Thiobacillus ferrooxidans, Thiobacillus thiooxidans and Leptospirillum ferrooxidans in these waters.

Antibodies, Bacterial↗