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Biomedical subjects

E Ferrer

Publications and source records attributed to E Ferrer.

At least 73 records · Page 4Linked to original sources
PubMed1998

Pattern recognition analysis of 1H NMR spectra from perchloric acid extracts of human brain tumor biopsies.

Pattern recognition techniques (factor analysis and neural networks) were used to investigate and classify human brain tumors based on the 1H NMR spectra of chemically extracted biopsies (n = 118). After removing information from lactate (because of variable ischemia times), unsupervised learning suggested that the spectra separated naturally into two groups: meningiomas and other tumors. Principal component analysis reduced the dimensionality of the data. A back-propagation neural network using the first 30 principal components gave 85% correct classification of meningiomas and nonmeningiomas. Simplification by vector rotation gave vectors that could be assigned to various metabolites, making it possible to use or to reject their information for neural network classification. Using scores calculated from the four rotated vectors due to creatine and glutamine gave the best classification into meningiomas and nonmeningiomas (89% correct). Classification of gliomas (n = 47) gave 62% correct within one grade. Only inositol showed a significant correlation with glioma grade.

Biomarkers, Tumor↗
PubMed1998

Brain metastases in endometrial carcinoma.

BACKGROUND: Brain metastases of endometrial carcinoma are rare. They tend to follow an unpredictable dissemination pattern, due to the different pathways that tumor cells can follow and to certain factors that influence their spread. When brain metastases occur, usually the disease is widely disseminated, but there are some exceptions such as the case presented here. METHODS: We report the case of a 76-year-old woman who presented a single occipital metastasis 18 months after a hysterectomy because of an endometrial carcinoma. No other metastases were found. DISCUSSION: We discuss the different dissemination pathways of endometrial carcinoma. Some hypotheses try to explain what determines the site of preference of distant metastases. The most accepted hypothesis suggests the presence of specific tumor cell receptors and endothelium receptors on the target organs, which would explain the preference of different cancers for different targets and for different areas inside the same target organ. CONCLUSION: Although brain metastases of endometrial carcinoma are rare and they usually occur in widely disseminated disease, they should be considered in patients with a single brain mass, even when the primary disease is unknown.

Aged↗
PubMed1998

Results of the biocompatible osteoconductive polymer (BOP) as an intersomatic graft in anterior cervical surgery.

Eighty-two patients operated on in our Department between 1989 and 1995 with an anterior cervical approach for soft and hard cervical disc herniations and cervical stenosis were included in this study. In 41 cases a heterologous intersomatic bovine graft (Surgibone) was used. Another 41 patients underwent surgery with a biocompatible osteoconductive polymer (BOP) as intervertebral graft. Both groups were retrospectively reviewed and compared with the objectives of evaluating the biodynamic behaviour of the grafts in the intersomatic space, the complications which appeared (specially those related to the grafts), the bone fusion rate achieved and the clinical outcome of the patients. The results of our study show that the BOP group presented a higher tendency to intersomatic space collapse 6 months after discectomy. There were no differences in the general surgical complications between both groups, but those related directly to the graft were significantly higher in the BOP group. The vast majority of the graft complications recorded had no clinical correlation. Without a strict radiological follow-up such complications would never have been discovered. Bone fusion in the BOP group was significantly slower and worse. Finally, the clinical outcome in both groups did not show any significant difference.

Animals↗
PubMed1997

Neuroendoscopic management of pineal region tumours.

The management of pineal tumours remains controversial. During 1994 we treated four consecutive adults (16-44 yrs) harbouring a pineal tumour with a neuroendoscopic procedure. All of them presented with hydrocephalus. Pre-operative workup included cranial computerized tomography (CT), craniospinal magnetic resonance imaging (MRI) and serum levels of biological tumour markers. The endoscopic procedure consisted of a third ventriculostomy followed by biopsy with a flexible, steerable neuroendoscope. Histological diagnosis was achieved in three patients who no longer required a shunt device. Recorded complications were: bleeding during ventriculostomy that prevented us from obtaining a good sample for biopsy, short-term memory loss that cleared over a two-week period, and transient increase of pre-operative hemiparesis. Complications and morbidity are emphasized so as to be avoided with further technical experience. Neuroendoscopy affords a minimally invasive way of reaching three objectives by one-step surgery in the management of pineal region lesions: 1) CSF sample for analysis of tumour markers. 2) Treatment of hydrocephalus by third ventriculostomy. 3) Several biopsy specimens can be obtained identifying tumours which will require further open surgery or adjuvant radiation and/or chemotherapy.

Adolescent↗
PubMed1997

Influence of different levels of neonatal mild/moderate hypoxia-ischemia in learning abilities of rats at the age of one month.

We studied the effects of mild/moderate hypoxia-ischemia in 90 newborn Wistar rats divided into 3 groups. Two of the three groups were submitted to two different levels of hypoxia (FiO2 = 0.05, group F5 and FiO2 = 0.1, group F10) and the third to normoxia (FiO2 = 0.21, group F21) in a thermoneutral and controlled environment. We examined their influence in a maze test 1 month later after two training trials, a 48-hour fasting period and handling stress just before starting the trial. The learning ability in animals exposed to FiO2 = 0.1 was lower (significantly higher number of squares crossed F10 = 37.57 +/- 20.8) than the others (F21 = 26.22 +/- 19.25; F5 = 26.56 +/- 14.97; p = 0.0481), while group F5 had the best learning improvement measured by the reduction in wrongly crossed squares (F5 day 25 = 25.08 +/- 19.9; day 26 = 13.04 +/- 13.91; day 30 = 10.08 +/- 9.66; p = 0.0427). These differences in group F5 as well as the maze solution profile (defined by analysis of 15 variables considered) was significantly closer to the control group F21 than the less hypoxied group F10. We discuss whether these paradoxical results in learning abilities reflect the influence of the hypoxic levels to which the newborn animals were submitted, or to the effects of uncontrolled variables in this study.

Animals↗
PubMed1997

pp65 antigenemia as a marker of future CMV disease and mortality in HIV-infected patients.

We retrospectively evaluated the role of pp65 antigenemia (AGM) as a marker of cytomegalovirus (CMV) disease and mortality in 241 HIV-infected patients with fever. Of 225 patients in whom CD4 count was available, 189 (84%) had counts below 100/microL and 209 (92.8%) below 200/microL, 149 patients had negative AGM (AGM-) and 92 had positive AGM (AGM+), AGM+ patients were at a more advanced stage of HIV disease, as evaluated by CD4 count (p < 0.001) and prior AIDS diagnosis (p < 0.001). Overall, 29 patients (12%) presented concomitant CMV disease (18 retinitis): 24 (26%) in the AGM+ group and 5 (3.3%) in the AGM- group (p < 0.001). AGM had a negative predictive value of 96.6% but a positive predictive value of 26% which increased to 65% if a cut-off of > 10 CMV-positive cells/10(5) leukocytes was considered. The cumulative rate of future CMV disease at 3 months was 0% in AGM patients, 3% in patients with AGM 1-10/10(5) and 36% in patients with AGM > 10/10(5). In a multivariate analysis, no antiretroviral therapy, AGM+ and CMV disease were independently associated with mortality. The role of AGM as a marker of present CMV disease is limited. However, quantitative AGM may select patients at a high risk of future CMV disease. In addition, AGM may be a marker of shorter survival in severely immunosuppressed HIV-infected patients.

AIDS-Related Opportunistic Infections↗
PubMed1996

Purification and biochemical characterization of gentisate 1,2-dioxygenase from Klebsiella pneumoniae M5a1.

Gentisate 1,2-dioxygenase (E.C.1.14.13) was purified to homogeneity from Klebsiella pneumoniae M5a1, a soil bacterium able to degrade a great variety of aromatic compounds. The molecular mass of the purified holoenzyme was 159 kDa and its structure was deduced to be a tetramer with 38 kDa per subunit. Gentisate 1,2-dioxygenase appears to contain Fe2+ in its active site. The optimum temperature for enzyme activity was estimated to be 30 degrees C, the optimum pH values varied between 8 and 9 and the isoelectric point was 4.7. Gentisate dioxygenase exhibited typical saturation kinetics and had an apparent K(m) of 52 microM for gentisate. Its amino acid content was determined to be very similar to that of the enzyme from Pseudomonas acidovorans.

Amino Acids↗
PubMed1996

Simple sequence repeat primers used in polymerase chain reaction amplifications to study genetic diversity in barley.

In combination with oligonucleotides of arbitrary sequence, 5' anchored oligonucleotides based on simple sequence repeats were used in polymerase chain reaction amplifications to produce barley DNA fingerprints. The aim of this work was (i) to develop a simple nonradioactive experimental procedure to reveal polymorphism in regions containing SSRs, (ii) to determine the genetic nature of polymorphisms, and (iii) to investigate the efficacy of polymorphisms contained in such fingerprints in disclosing genetic relationships between 14 European barley cultivars with known pedigrees. Different 10-mer oligonucleotides containing a dinucleotide motif were used as single primers and also in pairs with 10-mer oligonucleotides of arbitrary sequence. Further, the arbitrary oligonucleotides were used as single primers to produce RAPDs. Thirteen combinations of primers containing either GT(CA)4 or GC(CA)4 were selected on the basis of number and intensity of scorable bands in silver-stained 7% polyacrylamide gels. Of the fragments scored, 58.4% were polymorphic. Inheritance of these random amplified microsatellite polymorphic fragments (RAMP) was studied in doubled-haploid lines from the F1 of 'Steptoe' x 'Morex'. Fifty percent of the primers generated codominant markers. Genetic similarities between cultivars were estimated from RAMP and RAPD data. Principal coordinate analysis performed on RAMP data revealed a clear separation of winter six-rowed, winter two-rowed, and spring two-rowed barley. The dendograms generated faithfully reflected the genealogies of the barley cultivars. RAPD failed to show clearly the germplasm sources of the experimental cultivars.

Base Sequence↗
PubMed1995

Purification and characterization of the 3-hydroxybenzoate-6-hydroxylase from Klebsiella pneumoniae.

We isolated 3-hydroxybenzoate-6-hydroxylase (E.C.1.14.13.), an inducible enzyme that catalyzed the para-hydroxylation of 3-hydroxybenzoate (3-HBA) to 2,5-dihydroxybenzoate, from Klebsiella pneumoniae. Although the enzyme was found to be mainly induced by its substrate, a coordinated induction of 3-hydroxybenzoate hydroxylase and gentisate dioxygenase was also observed in the presence of the product of the reaction. The purified enzyme was a monomer with a molecular mass of 42,000. It contained FAD as a prosthetic group, utilized NADH or NADPH with similar efficiencies and its activity was inhibited by Cu2+, Fe2+ and Hg2+. Other properties, such as induction mechanism and kinetic parameters were also studied. Moreover, for the first time the amino acid composition of a 3-hydroxybenzoate-6-hydroxylase was determined.

Amino Acids↗
PubMed1995

Purification and characterization of 4-hydroxybenzoate 3-hydroxylase from a Klebsiella pneumoniae mutant strain.

Unlike the parent wild-type strain, the Klebsiella pneumoniae mutant strain MAO4 has a 4-HBA+ phenotype. The capacity of this mutant to take up and metabolize 4-hydroxybenzoate (4-HBA) relies on the expression of a permease and an NADPH-linked monooxygenase (4-HBA-3-hydroxylase). Both enzymes are normally expressed at basal levels, and only the presence of 4-HBA in the media enhances their activities. Strikingly, when the Acinetobacter calcoaceticus pobA gene encoding 4-hydroxybenzoate-3-hydroxylase was expressed in hydroxybenzoate K. pneumoniae wild-type, the bacteria were unable to grow on 4-HBA, suggesting that the main difference between the wild-type and the mutant strain is the capability of the latter to take up 4-HBA. 4-HBA-3-hydroxylase was purified to homogeneity by affinity, gel-filtration, and anion-exchange chromatography. The native enzyme, which appeared to be a dimer of identical subunits, had an apparent molecular mass of 80 kDa and a pI of 4.6. Steady-state kinetics were analyzed; the initial velocity patterns were consistent with a concerted substitution mechanism. The purified enzyme had 362 amino acid residues, and a tyrosine seemed to be involved in substrate activation.

4-Hydroxybenzoate-3-Monooxygenase↗
PubMed1995

Giant cephalhematoma in a 15-year-old boy. Unilateral amaurosis as the main complication.

BACKGROUND: The term "cephalhematoma" is applied to a collection of blood under the periosteum of a skull bone. It most frequently occurs in the neonatal period and is rare at other times of life. METHODS AND RESULTS: We report on a 15-year-old boy with a subperiosteal hematoma involving the whole cranial surface. Surgical drainage was performed. In the immediate postoperative course, the patient developed a progressive decrease in the right eye visual acuity. An orbital computed tomographic scan revealed the retro-orbital subperiosteal extension of the hematoma. A second surgical procedure was necessary to obtain visual recovery. CONCLUSIONS: The occurrence of cephalhematoma in adults is exceptional. However, it may lead to serious complications. Surgical treatment should be aimed to avoid retro-orbital extension of the hematoma.

Adolescent↗
PubMed1995

The natural history of arachnoid cysts: endoscopic and cine-mode MRI evidence of a slit-valve mechanism.

Arachnoid cysts are space-occupying lesions filled with CSF-like content and surrounded by a membrane resembling arachnoid matter. They are regarded as a development abnormality of the arachnoid, originating from a splitting or duplication of this membrane. However, precise etiology and natural history remain controversial. Different hypotheses have been developed including agenesis of brain structures, arachnoiditis, active fluid secretion, and pulsatile pump. We present a review of the literature concerning these items and report one case of a suprasellar arachnoid cyst in which a slit-valve mechanism was observed by means of cine-mode MRI preoperatively and confirmed during the endoscopic intervention.

Arachnoid↗
PubMed1995

Polymer production by Klebsiella pneumoniae 4-hydroxyphenylacetic acid hydroxylase genes cloned in Escherichia coli.

The expression of Klebsiella pneumoniae hpaA and hpaH genes, which code for 4-hydroxyphenylacetic acid hydroxylase in Escherichia coli K-12 derivative strains, is associated with the production of a dark brown pigment in the cultures. This pigment has been identified as a polymer which shows several of the characteristics reported for microbial melanins and results from the oxidative activity of 4-hydroxyphenylacetic acid hydroxylase on some dihydroxylated compounds to form o-quinones. A dibenzoquinone is formed from the oxidation of different mono- or dihydroxylated aromatic compounds by the enzyme prior to polymerization. We report a hydroxylase activity, other than tyrosinase, that is associated with the synthesis of a bacterial melanin.

Cloning, Molecular↗
PubMed1995

Chromosomal distribution of a repeated DNA sequence from C-genome heterochromatin and the identification of a new ribosomal DNA locus in the Avena genus.

Satellite DNA specific to the oat C genome was sequenced and located on chromosomes of diploid, tetraploid, and hexaploid Avena ssp. using in situ hybridization. The sequence was present on all seven C genome chromosome pairs and hybridized to the entire length of each chromosome, with the exception of the terminal segments of some chromosome pairs. Three chromosome pairs belonging to the A genome showed hybridization signals near the telomeres of their long arms. The existence of intergenomic chromosome rearrangements and the deletions of the repeated units are deduced from these observations. The number of rDNA loci (18S-5.8S-26S rDNA) was determined for the tetraploid and hexaploid oat species. Simultaneous in situ hybridization with the satellite and rDNA probes was used to assign the SAT chromosomes of these species to their correct genomes.

Avena↗
PubMed1995

Molecular characterization and chromosome location of repeated DNA sequences in Hordeum species and in the amphiploid tritordeum (x Tritordeum Ascherson et Graebner).

Genomic DNA from 19 species and subspecies representing the four basic genomes (H, I, X, and Y) of Hordeum was restricted with HaeIII and hybridized with two repeated DNA sequences of Hordeum chilense. The potential use of repeated sequences in ascertaining genomic affinities within the genus Hordeum was studied by comparing restriction fragment patterns. The study demonstrated the following: (i) species that shared a basic genome showed more similar hybridization fragment patterns than species with different genomes, whether with pHch1 or pHch3; (ii) hybridization with pHch1 revealed the presence of certain fragments limited to the species with a H genome; and (iii) the alloploid nature of species like H. jubatum was confirmed. The chromosomal distribution of the two repeated sequences was studied in species representing each basic genome and in the amphiploid tritordeum using fluorescent in situ hybridization. No interspecific differences were found between the diploid species. In situ experiments indicated the alloploid nature of H. depressum. Both sequences allow H. chilense chromatin to be distinguished from wheat chromosomes in tritordeum.

Base Sequence↗
PubMed1995

[Changes in protein repletion markers in undernourished patients receiving enteral nutrition and its relation with energy and nitrogen balance].

AIM: To study the relationship between the changes in protein repletion indicators and calorie and nitrogen balance in undernourished patients receiving enteral nutrition. PATIENTS AND METHODS: Fourteen patients (11 female, age range 55-85 years old) with an initial serum albumin below 3.5 g/dl or serum transferrin below 200 mg/dl, which received enteral nutrition, were studied. On days one and ten of nutritional support, indirect calorimetry, nitrogen balance and serum levels of albumin, transferrin, pre-albumin and total lymphocyte count were measured. RESULTS: Initial resting energy expenditure was 25.1 +/- 5 Kcal/kg/day (115.4 +/- 20% of that predicted by Harris Benedict equations) and urinary urea nitrogen 5.4 +/- 3.7 g/day. Initial and final nitrogen balances were 66.9 +/- 71 and 81.4 +/- 105.9 mg N/kg/day and mean energy balance throughout the study was +9.0 +/- 7.2 Kcal/kg/day. During the ten days of nutritional support, albumin improved significantly in 0.35 +/- 0.43 g/dl (15.2 +/- 19.8%). Transferrin, pre-albumin and total lymphocyte count did not change significantly. The changes in these last parameters did not correlate with nitrogen or calorie balance. CONCLUSIONS: Probably other factors, besides nutritional balances, influence serum protein levels and these may not change despite an adequate nutritional repletion.

Aged↗
PubMed1994

3,4-Dihydroxyphenylacetate 2,3-dioxygenase from Klebsiella pneumoniae, a Mg(2+)-containing dioxygenase involved in aromatic catabolism.

3,4-Dihydroxyphenylacetate 2,3-dioxygenase, an extradiol-ring-cleavage dioxygenase, has been purified from Klebsiella pneumoniae to homogeneity. The enzyme has an M(r) of 102,000 in its tetrameric form with an M(r) of 25,500 for each subunit. Unlike most other dioxygenases, the enzyme reported here contains Mg2+, as determined by atomic-absorption spectrophotometry and plasma emission metal analysis. The enzyme was shown to contain approx. 1 g-atom of Mg2+/mol of protein and we suggest an alpha 4 Mg2+ quaternary structure. This is the first report of a dioxygenase containing Mg2+ in its structure.

Cloning, Molecular↗