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Biomedical subjects

F J Fernández

Publications and source records attributed to F J Fernández.

At least 19 recordsLinked to original sources
PubMed2005

Denitrification potential of industrial wastewaters.

Nitrate utilisation batch experiments have been carried out with different agro-food industrial wastewaters. The results obtained were modelled using a modification of the ASM2d to determine the main kinetic and stoichiometric parameters: denitrification rate with fermentation products (q(N-SA)) and with fermentable substrates (q(N-SF)); fermentation products and fermentable substrates consumption rates, (qSA) and (qSF), respectively; yield coefficient with fermentation products (Y(H-SA)) and with fermentable substrates (Y(H-SF)) and saturation coefficient for growth on fermentation products (K(H-SA)). It was found that fermentation products (SA) and fermentable substrates (SF) consumption rates can be assumed to be both constant and independent of the agro-food industrial wastewater used, with values of 14.6 and 5.4 (mg S(COD) g COD-X(-1)OHO h(-1)), respectively. The mean denitrification rates obtained with each agro-food industrial wastewater ranged from 1.5 to 2.5 (mg S(N) g COD-X(-1)OHO h(-1)), values slightly lower to the obtained with domestic wastewater (2.7 mg S(N) g COD-X(-1)OHO h(-1)). Given the substrate consumption rate and the denitrification rate, the yields with fermentation products and fermentable substrates for each wastewater were determined. The values obtained for the yields ranged from 0.50 to 0.69 on using SA and from 0.50 to 0.70 on using SF. Having determined these parameters, the denitrification potential (DNP) was evaluated for each agro-food wastewater. Wastewater from slaughterhouses gave the lowest DNP (22.6 mg S(N) g S(-1)COD), whereas wastewater from potato and tomato processing plants gave the highest values (126.5 and 128.2 mg S(N) g S(-1)COD), respectively), which are very similar to that obtained with domestic wastewater (130.3 and 128.2 mg S(N) g S(-1)COD). Taking into account the low N/COD ratio presented in the agro-food wastewaters, the last wastewaters are the most indicated to enhance the nitrogen removal in the WWTP. Finally, a relationship between the denitrification rates of several agro-food industrial wastewaters and their respective S(A)/(S(A) + S(F)) ratio was obtained. This relationship can be used to estimate the mean denitrification rate of an agro-food industrial wastewater.

Bioreactors↗
PubMed2004

ECG characterization of paroxysmal atrial fibrillation: parameter extraction and automatic diagnosis algorithm.

Paroxysmal atrial fibrillation (PAF) is one of the most common heart arrhythmias. It is very difficult to detect unless an explicit Atrial Fibrillation episode occurs during the exploration. The present paper describes a number of low level parameters extracted from ECG traces where no Atrial Fibrillation process is present. The ability of this parameter set to characterize PAF patients is studied and discussed. Based on these parameters a modular automatic classification algorithm for PAF diagnosis is developed and evaluated.

Algorithms↗
PubMed2004

A fungal phenoloxidase (tyrosinase) involved in pentachlorophenol degradation.

Amylomyces rouxii eliminated 85% of initial pentachlorophenol (PCP) at 12.5 mg l(-1) when grown with 0.1 g tyrosine l(-1), but only 55% without tyrosine. Addition of tyrosine in the culture medium increased the monophenolase activity by 1.8-fold. Tyrosinase is thus indicated to be the phenoloxidase involved in PCP degradation by A. rouxii .

Biodegradation, Environmental↗
PubMed2004

Automatic Paroxysmal Atrial Fibrillation Based on not Fibrillating ECGs.

OBJECTIVES: The objective of the paper is to describe an automatic algorithm for Paroxysmal Atrial Fibrillation (PAF) Detection, based on parameters extracted from ECG traces with no atrial fibrillation episode. The modular automatic classification algorithm for PAF diagnosis is developed and evaluated with different parameter configurations. METHODS: The database used in this study was provided by Physiobank for The Computers in Cardiology Challenge 2001. Each ECG file in this database was translated into a 48 parameter vector. The modular classification algorithm used for PAF diagnosis was based on the nearest K-neighbours. Several configuration options were evaluated to optimize the classification performance. RESULTS: Different configurations of the proposed modular classification algorithm were tested. The uni-parametric approach achieved a top classification rate value of 76%. A multi-parametric approach was configured using the 5 parameters with highest discrimination power, and a top classification rate of 80% was achieved; different functions to typify the parameters were tested. Finally, two automatic parametric scanning strategies, Forward and Backward methods, were adopted. The results obtained with these approaches achieved a top classification rate of 92%. CONCLUSIONS: A modular classification algorithm based on the nearest K-neighbours was designed. The classification performance of the algorithm was evaluated using different parameter configurations, typification functions and number of K-neighbors. The automatic parametric scanning techniques achieved much better results than previously tested configurations.

Algorithms↗
PubMed2003

Acclimation of mesophilic anaerobic sludge to thermophilic conditions: PCR genera detection methodology.

In Mexico, sludge from wastewater treatment plants is a public health problem, especially for the infant population due to the presence of pathogens and parasite eggs. Therefore, it is of great interest to apply proper treatment methods for those wastes. An option proposed for the removal of possible infectious sources is thermophilic anaerobic digestion, even though a limitation for its acceptance is the slow start-up of the reactors. The transformation of a mesophilic anaerobic sludge for its utilization as a thermophilic inoculum, by means of direct temperature increase up to 55 degrees C and feeding of the inoculum with synthetic medium was possible in two months. As a main part of the work and with the objective of evaluating the changes in the methanogenic microbial population during the sludge treatment, a specific detection technique for these bacteria has been developed and validated, based on the use of the polymerase chain reaction (PCR).

Bacteria↗
PubMed2002

[Selective ophthalmic artery fibrinolysis in acute central retinal artery occlusion].

PURPOSE: To evaluate efficacy and reliability of local intra-arterial fibrinolysis (LIF) in Retinal Central Artery Occlusion (RCAO). MATERIAL AND METHOD: We have studied 12 patients with RCAO. Seven patients (group I) were treated with conventional therapy and 5 patients (group II) underwent treatment with urokinase via transcutaneous femoral catheter into the ophthalmic artery. Thereafter patients received heparin sulfate for 3 days. RESULTS: Mean follow up was 14 months and mean time from onset of symptoms to the beginning of therapy was 11 hours. One patient in group I showed improvement of visual acuity (from counting fingers to 0.1). In all patients in group II there was angiographic evidence of improved perfusion of retinal arteries and 4 patients (80%) showed improvement in visual acuity. The best results were obtained when LIF was performed before 10 hours after onset of symptoms. No complications were observed after the fibrinolysis treatment. CONCLUSION: LIF in ophtalmic arteries for the treatment of RCAO reduces dosage of fibrinolytic agents and becomes a safe and useful treatment during the first hours post RCAO.

Aged↗
PubMed2001

[Tropical endomyocardial fibrosis or Davies disease. A case report].

Endomyocardial fibrosis is a restrictive endomyocardial myocardiopathy of unclear etiology, it is an endemic disease in tropical and subtropical countries. The patients are usually young and the disease has an insidious onset and poor prognosis. Surgery may lead to clinical improvement and prolong life expectancy, although it is only a palliative treatment and does not stop disease progression. We present a case of endomyocardial fibrosis from Equatorial Guinea with severe clinical involvement and clear improvement following surgery. The current etiopathogenic hypothesis, the results obtained and the management of these cases, which are infrequent in Spain, are discussed. We also comment upon the differences with the historically related Loeffler syndrome according to one of the etiopathogenic hypotheses.

Adult↗
PubMed2001

[Early glaucomatous changes in neuroretinal rim shape].

PURPOSE: To assess the differences in neuroretinal rim shape in ocular hypertensive patients (normal white-white automated perimetry) with and without perimetric injury in the short wave length automated perimetry (blue-yellow). MATERIAL AND METHODS: 72 eyes from 72 hypertensive ocular patients with normal achromatic automated perimetry examination were included. Forty eyes had normal short wave length automated perimetries while 32 subjects presented an abnormal condition. The neuroretinal rim morphology was quantified by means of a planimetric study from the papillary images obtained with confocal laser scanning. RESULTS: The subjects with abnormal blue-yellow perimetry showed a decrease in the neuroretinal rim area in the inferior and temporal positions. The differences were significant (p<0.05) at the 9 o'clock position (below the middle line) and almost significant (p<0.10) at the 10 o'clock position. CONCLUSIONS: There are differences in the neuroretinal rim shape in ocular hypertensive subjects with normal achromatic perimetry according to whether there are abnormalities in the blue-yellow perimetry.

Adult↗
PubMed2000

[Epididymal carcinoma. Bibliographic review in reference to a case].

OBJECTIVE: To describe a case of epithelial cell paratesticular carcinoma of the epididymis and briefly review the literature on this tumor type. METHODS/RESULTS: A 69-year-old male consulted for a testicular mass and intrascrotal pain, together with irritative bladder symptoms. The patient underwent orchidectomy, but consulted again shortly thereafter for persistent irritative bladder symptoms. A TUR biopsy of the bladder wall demonstrated undifferentiated carcinoma arising from the epididymis. The patient did not respond to chemotherapy. He developed systemic metastasis and died 4 months after the diagnosis. CONCLUSIONS: Carcinoma of the epididymis is a rare malignant paratesticular tumor arising from the epithelial cells with a very poor prognosis. Its clinical features are unspecific and this tumor type should be taken into account when making differential diagnosis from intrascrotal masses arsing from other causes. Due to the rarity of this disease, it has not been possible to identify treatments that might achieve better results.

Aged↗
PubMed1998

Identification, characterization, and chromosomal organization of the ftsZ gene from Brevibacterium lactofermentum.

The ftsZ gene was cloned from the chromosomal DNA of Brevibacterium lactofermentum by the polymerase chain reaction (PCR) using two oligonucleotides designed from two conserved regions found in most of the previously cloned and sequenced ftsZ genes from other microorganisms. ftsZ is a single-copy gene in corynebacteria and is located downstream from ftsQ and murC, indicating linkage between genes involved in peptidoglycan synthesis (mur genes) and genes involved in cell division (fts genes). The organisation of the cluster is similar to that in Streptomyces and different from those of Escherichia coli or Bacillus subtilis because ftsA is not located upstream of ftsZ. The gene was expressed in E. coli using the T7 expression system; the calculated molecular weight of the expressed protein was 50 kDa. Expression of the B. lactofermentum ftsZ gene in E. coli inhibited cell division and led to filamentation. The ftsZ gene of this organism does not complement ftsZ mutations or deletions in E. coli, when cloned on low or high-copy-number vectors.

Amino Acid Sequence↗
PubMed1997

Expression of the cefG gene is limiting for cephalosporin biosynthesis in Acremonium chrysogenum.

The conversion of deacetylcephalosporin C to cephalosporin C is inefficient in most Acremonium chrysogenum strains. The cefG gene, which encodes deacetylcephalosporin C acetyltransferase, is expressed very poorly in A. chrysogenum as compared to other genes of the cephalosporin pathway. Introduction of additional copies of the cefG gene with its native promoter (in two different constructions with upstream regions of 1056 bp and 538 bp respectively) did not produce a significant increase of the steady-state level of the cefG transcript. Expression of the cefG gene from the promoters of (i) the glyceraldehyde-3-phosphate dehydrogenase (gpd) gene of Aspergillus nidulans, (ii) the glucoamylase (gla) gene of Aspergillus niger, (iii) the glutamate dehydrogenase (gdh) and (iv) the isopenicillin N synthase (pcbC) genes of Penicillium chrysogenum, led to very high steady-state levels of cefG transcript and to increased deacetylcephalosporin-C acetyltransferase protein concentration (as shown by immunoblotting) and enzyme activity in the transformants. Southern analysis showed that integration of the new constructions occurred at sites different from that of the endogenous cefG gene. Cephalosporin production was increased two- to threefold in A. chrysogenum C10 transformed with constructions in which the cefG gene was expressed from the gdh or gpd promoters as a result of a more efficient acetylation of deacetylcephalosporin C.

Acetyltransferases↗
PubMed1997

Characterization of the bip gene of Aspergillus awamori encoding a protein with an HDEL retention signal homologous to the mammalian BiP involved in polypeptide secretion.

A DNA fragment containing an open reading frame of 2016 nucleotides has been cloned from the DNA of Aspergillus awamori by hybridization with a probe internal to the KAR2 (BiP) gene of Saccharomyces cerevisiae. The 73.4-kDa-encoded protein showed very high similarity to the endoplasmic reticulum (ER) lumenal BiP protein of S. cerevisiae, Kluyveromyces lactis, Schizosaccharomyces pombe, and animal and plant cells. The BiP protein contains a polar N-terminal end followed by a 18-amino-acid strongly hydrophobic region corresponding to the leader peptide for transport through the ER membrane. In the C-terminal region the protein ends with the HDEL canonical ER retention signal that targets proteins to the lumen of the ER. The A. awamori bip gene contains three introns as shown by cloning and sequencing the putative intron regions from a cDNA library. The bip gene is transcribed as a monocistronic mRNA of 2.4 kb. Two transcription start sites located 160 and 233 bp upstream of the first translated ATG were identified by primer extension. The promoter region showed no consensus TATA box but it contains CCAAT and CreA boxes known to be involved in both stress and carbon-catabolite regulation of fungal promoters.

Amino Acid Sequence↗
PubMed1997

[Early diagnosis of glaucoma with pattern-ERG].

PURPOSE: Current electrophysiological techniques for diagnosis of glaucoma include pattern-electroretinogram (PERG) and visual evoked potentials (VEP) but PERG has been recognized over the last decade as a good functional indicator of retinal ganglion cells. METHODS: An investigation has been carried out on 171 eyes of 89 subjects using both PERG (gold foil electrodes) and VEP. One group of 32 subjects with ocular hypertension (OHT) and another group of 27 subjects having simple chronic glaucoma (SCG) were compared with a control group of 30 healthy age-matched subjects. RESULTS: For PERG, the amplitude of the P50 and N95 components was measured but statistically significant differences were shown for N95 only in SCG (p < 0.01) and OHT (p < 0.05). FFT analysis on each PERG showed a dominant frequency of 3.3 Hz for OHT subjects versus 9.9 Hz for those of the control group. For VEP, the amplitude and latency of P100 was analysed. P100 latency showed significant delay (p < 0.05) in the SCG group only. CONCLUSIONS: These findings suggest that N95-amplitude is the most sensitive electrophysiologic parameter for early glaucoma detection. By comparing data of this work with a previous study using wire (anchor shaped) electrodes we demonstrate higher amplitude and lesser variability of the N95 component for gold foil electrodes, therefore this latter type of recording is acknowledged as the most sensitive for detection of early impairment of ganglion cells in HTO patients.

Adult↗
PubMed1995

The penicillin gene cluster is amplified in tandem repeats linked by conserved hexanucleotide sequences.

The penicillin biosynthetic genes (pcbAB, pcbC, penDE) of Penicillium chrysogenum AS-P-78 were located in a 106.5-kb DNA region that is amplified in tandem repeats (five or six copies) linked by conserved TTTACA sequences. The wild-type strains P. chrysogenum NRRL 1951 and Penicillium notatum ATCC 9478 (Fleming's isolate) contain a single copy of the 106.5-kb region. This region was bordered by the same TTTACA hexanucleotide found between tandem repeats in strain AS-P-78. A penicillin overproducer strain, P. chrysogenum E1, contains a large number of copies in tandem of a 57.9-kb DNA fragment, linked by the same hexanucleotide or its reverse complementary TGTAAA sequence. The deletion mutant P. chrysogenum npe10 showed a deletion of 57.9 kb that corresponds exactly to the DNA fragment that is amplified in E1. The conserved hexanucleotide sequence was reconstituted at the deletion site. The amplification has occurred within a single chromosome (chromosome I). The tandem reiteration and deletion appear to arise by mutation-induced site-specific recombination at the conserved hexanucleotide sequences.

Base Sequence↗
PubMed1995

Three genes hrdB, hrdD and hrdT of Streptomyces griseus IMRU 3570, encoding sigma factor-like proteins, are differentially expressed under specific nutritional conditions.

Three genes (hrd) homologous to the rpoD gene of Escherichia coli, that encode sigma factor-like proteins, have been cloned from DNA of the candicidin-producing strain Streptomyces griseus IMRU 3570. They are located in different regions of the chromosome. Sequence analysis showed that the first one is analogous to the hrdB gene of S. coelicolor. The second showed high similarity to the hrdD gene of S. coelicolor and S. aureofaciens and is linked, as in S. coelicolor, to a N-acetyltransferase-encoding gene (nat) distantly related to the pat and bar genes that encode resistance to bialafos. The third showed no close homology with other known hrd genes from actinomycetes and has been named hrdT. Functional domains in the three S. griseus Hrd proteins are highly conserved in relation to those of the sigma 70 protein family. Northern analysis showed that hrdB is expressed as a 1.9-kb transcript during active growth in phosphate-rich medium, but it is less efficiently transcribed under sporulation conditions (phosphate-starved) or after a heat-shock treatment. Two other shorter transcripts of 1.2 and 0.7 kb were also detected with the same probe. The hrdD gene is transcribed as a single 1.1-kb transcript under sporulation conditions following nutritional shiftdown and, to a lower extent, during growth conditions in phosphate-rich medium. The hrdT gene is weakly transcribed (1.5-kb RNA) under all conditions tested. The hrd-encoded sigma factors probably recognize actinomycetes promoters (SEP type) with E. coli-like consensus sequences.

Amino Acid Sequence↗
PubMed1994

Expression of genes and processing of enzymes for the biosynthesis of penicillins and cephalosporins.

The genes pcbAB, pcbC and penDE encoding the enzymes (alpha-aminoadipyl-cysteinyl-valine synthetase, isopenicillin N synthase and isopenicillin N acyltransferase, respectively) involved in the biosynthesis of penicillin have been cloned from Penicillin chrysogenum and Aspergillus nidulans. They are clustered in chromosome I (10.4 Mb) of P. chrysogenum, in chromosome II of Penicillium notatum (9.6 Mb) and in chromosome VI (3.0 Mb) of A. nidulans. Each gene is expressed as a single transcript from separate promoters. Enzyme regulation studies and gene expression analysis have provided useful information to understand the control of genes involved in penicillin biosynthesis. The enzyme isopenicillin N acyltransferase encoded by the penDE gene is synthesized as a 40 kDa protein that is (self)processed into two subunits of 29 and 11 kDa. Both subunits appear to be required for acyl-CoA 6-APA acyltransferase activity. The isopenicillin N acyltransferase was shown to be located in microbodies, whereas the isopenicillin N synthase has been reported to be present in vesicles of the Golgi body and in the cell wall. A mutant in the carboxyl-terminal region of the isopenicillin N acyltransferase lacking the three final amino acids of the enzymes was not properly located in the microbodies and failed to synthesize penicillin in vivo. In C. acremonium the genes involved in cephalosporin biosynthesis are separated in at least two clusters. Cluster I (pcbAB-pcbC) encodes the first two enzymes (alpha-aminoadipyl-cysteinyl) valine synthetase and isopenicillin N synthase) of the cephalosporin pathway which are very similar to those involved in penicillin biosynthesis. Cluster II (cefEF-cefG), encodes the last three enzymatic activities (deacetoxycephalosporin C synthetase/hydroxylase and deacetylcephalosporin C acetyltransferase) of the cephalosporin pathway. It is unknown, at this time, if the cefD gene encoding isopenicillin epimerase is linked to any of these two clusters. Methionine stimulates cephalosporin biosynthesis in cultures of three different strains of A. chrysogenum. Methionine increases the levels of enzymes (isopenicillin N synthase and deacetylcephalosporin C acetyltransferase) expressed from genes (pcbC and cefG respectively) which are separated in the two different clusters of cephalosporin biosynthesis genes. This result suggests that both clusters of genes have regulatory elements which are activated by methionine. Methionine-supplemented cells showed higher levels of transcripts of the pcbAB, pcbC, cefEF genes and to a lesser extent of cefG than cells grown in absence of methionine. The levels of the cefG transcript were very low as compared to those of pcbAB, pcbC and cefEF.(ABSTRACT TRUNCATED AT 400 WORDS)

Acyltransferases↗