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M Poza

Publications and source records attributed to M Poza.

At least 19 recordsLinked to original sources
PubMed2006

Proposal of a method for the genetic transformation of Gordonia jacobaea.

AIMS: Gordonia jacobaea is a recently isolated bacterial species with potential industrial application on account of its ability to store large quantities of trans-canthaxanthin. Its genetic manipulation is, however, difficult and cumbersome owing to the presence of mycolic acids in the cell wall and, especially, because of current lack of knowledge about its basic genetics. The present work describes a method for the genetic transformation of G. jacobaea. METHODS AND RESULTS: Gordonia jacobaea was grown in media supplemented with different glycine, penicillin G and isoniazid concentrations. The temperature, carbon source, growth phase and ultrasounds were analyzed for improving the method efficiency. The cells were finally transformed by electroporation. Finally, the method was applied to Brevibacteriumlactofermentum and Gordonia bronchialis. CONCLUSIONS: The growth of G. jacobaea in the presence of glycine and isoniazid is essential for obtaining electrocompetents cells. The temperature, growth phase and ultrasounds appeared as the main factors for increasing the transformation efficiency. The use of shuttle plasmids became necessary. The method described can be used with other Corynebacteria species. SIGNIFICANCE AND IMPACT OF THE STUDY: Because of the importance of the CNM group (Corynebacteria, Nocardia and Mycobacteria genera) in different areas such as industry, bioremediation improve the knowledge of their molecular mechanisms are becoming essential. The method described here improves the genetic manipulation of this group of bacteria.

Anti-Bacterial Agents↗
PubMed2006

Fluorescein thiocarbamoyl-kappa-casein assay for the specific testing of milk-clotting proteases.

Milk-clotting proteases, which are widely used in the cheese-making industry, are enzymes that use soluble caseins as their preferential substrates. Here, we propose a modification to a method previously described for the specific determination of milk-clotting proteases by using kappa-casein labeled with fluorescein isothiocyanate as substrate. Validation of the modified method was confirmed using natural bacterial, fungal, plant, and animal milk-clotting proteases, as well as a milk-clotting enzyme of recombinant origin. The new modified method described here allowed specific quantification of the activity of milk-clotting proteases in a very sensitive way and permitted determination of the appropriate kinetic parameters of all the enzymes tested, consistent with their origin and degree of purity.

Abomasum↗
PubMed2005

Meningiomas after radiation-therapy for benign astrocytomas.

A 4.5 year-old-girl was submitted to subtotal removal of a benign astrocytoma of the left temporal lobe with basal ganglia extension and given radiotherapy. At age 27, she was found to harbor a right posterior frontal meningioma that was totally removed. A recurrence of the right convexity meningioma was again excised after a 4-year interval. The authors report this case to illustrate the possibility of the appearance of radiation-induced meningiomas after an interval of 22 years and briefly discuss 16 previous reports on this occurrence in benign astrocytomas.

Aphasia↗
PubMed2004

Measurement of motor disability in MPTP-treated macaques using a telemetry system for estimating circadian motor activity.

The parkinsonian symptoms of primates after MPTP exposure can be measured by several visual methods (classical motor scores). However, these methods have a subjective bias, especially as regards the evaluation of the motor activity. Computerized monitoring systems represent an unbiased method for measuring the motor disability of monkeys after MPTP administration. In this work the motor activity of monkeys before and after MPTP administration is measured and compared with the activity of a control intact group by means of a telemetry system. A pronounced decrease in motor activity was observed after MPTP administration. These results suggest the monitoring method used is suited for characterizing the motor incapacity and possible improvements following treatments to test different therapies to control Parkinson's disease in MPTP models involving primates.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed2004

Cystic mature teratoma of the filum terminale in an adult. Case report and review of the literature.

Intradural spinal teratoma is a very rare entity, more prevalent in childhood, that may associate with dysraphic defects. The authors report a 46 years old man with a cauda equina syndrome and an L1-2 tumor. An L1-2 laminectomy was performed and a mass was resected at the base of the filum terminale, which was in contact with the conus medullaris. Histopathological diagnosis was of cystic mature teratoma. Spinal teratomas may be found anywhere along the spine, but are more frequent in the cauda equina. We discuss the origin of these tumors and review the literature concerning these lesions.

Cauda Equina↗
PubMed2004

Ancient genes of Saccharomyces cerevisiae.

Amber is a plant resin mainly produced by coniferous trees that, after entrapping a variety of living beings, was subjected to a process of fossilization until it turned into yellowish, translucent stones. It is also one of the best sources of ancient DNA on which to perform studies on evolution. Here a method for the sterilization of amber that allows reliable ancient DNA extraction with no actual DNA contamination is described. Working with insects taken from amber, it was possible to amplify the ATP9, PGU1 and rRNA18S ancient genes of Saccharomyces cerevisiae corresponding to samples from the Miocene and Oligocene. After comparison of the current genes with their ancient (up to 35-40 million years) counterparts it was concluded that essential genes such as rRNA18S are highly conserved and that even normal 'house-keeping' genes, such as PGU1, are strikingly conserved along the millions of years that S. cerevisiae has evolved.

Amber↗
PubMed2004

Cloning and expression of clt genes encoding milk-clotting proteases from Myxococcus xanthus 422.

The screening of a gene library of the milk-clotting strain Myxococcus xanthus 422 constructed in Escherichia coli allowed the description of eight positive clones containing 26 open reading frames. Only three of them (cltA, cltB, and cltC) encoded proteins that exhibited intracellular milk-clotting ability in E. coli, Saccharomyces cerevisiae, and Pichia pastoris expression systems.

Aspartic Acid Endopeptidases↗
PubMed2003

Production and characterization of the milk-clotting protease of Myxococcus xanthus strain 422.

The cheese industry is seeking novel sources of enzymes for cheese production. Microbial rennets have several advantages over animal rennets. (1) They are easy to generate and purify and do not rely on the availability of animal material. (2) The production of microbial clotting enzymes may be improved by biotechnological techniques. In this work, the biochemical characterization of a novel milk-clotting extracellular enzyme from Myxococcus xanthus strain 422 and a preliminary evaluation of its cheese-producing ability are reported. Strain 422 was selected from four M. xanthus strains as the best producer of extracellular milk-clotting activity, based on both its enzyme yield and specific milk-clotting activity, which also afforded lower titration values than enzymes from the three other M. xanthus strains. The active milk-clotting enzyme from M. xanthus strain 422 is a true milk-clotting enzyme with a molecular mass of 40 kDa and a pI of 5.0. Highest milk-clotting activity was at pH 6 and 37 degrees C. The enzyme was completely inactivated by heating for 12 min at 65 degrees C. The crude enzyme preparation was resolved by anion-exchange chromatography into two active fractions that were tested in cheese production assays of compositional (dry matter, fat content, fat content/dry-matter ratio, and moisture-non-fat content) and physicochemical properties (firmness, tensile strength, pH and Aw) of the milk curds obtained. Purified protein fraction II exhibited a significantly higher milk-clotting ability than either protein fraction I or a total protein extract, underlining the potential usefulness of M. xanthus strain 422 as a source of rennet for cheese production.

Animals↗
PubMed2003

Genetic basis of microbial carotenogenesis.

The synthesis of carotenoids begins with the formation of a phytoene from geranylgeranyl pyrophosphate, a well conserved step in all carotenogenic organisms and catalyzed by a phytoene synthase, an enzyme encoded by the crtB ( spy) genes. The next step is the dehydrogenation of the phytoene, which is carried out by phytoene dehydrogenase. In organisms with oxygenic photosynthesis, this enzyme, which accomplishes two dehydrogenations, is encoded by the crtP genes. In organisms that lack oxygenic photosynthesis, dehydrogenation is carried out by an enzyme completely unrelated to the former one, which carries out four dehydrogenations and is encoded by the crtI genes. In organisms with oxygenic photosynthesis, dehydrogenation of the phytoene is accomplished by a zeta-carotene dehydrogenase encoded by the crtQ ( zds) genes. In many carotenogenic organisms, the process is completed with the cyclization of lycopene. In organisms exhibiting oxygenic photosynthesis, this step is performed by a lycopene cyclase encoded by the crtL genes. In contrast, anoxygenic photosynthetic and non-photosynthetic organisms use a different lycopene cyclase, encoded by the crtY ( lyc) genes. A third and unrelated type of lycopene beta-cyclase has been described in certain bacteria and archaea. Fungi differ from the rest of non-photosynthetic organisms in that they have a bifunctional enzyme that displays both phytoene synthase and lycopene cyclase activity. Carotenoids can be modified by oxygen-containing functional groups, thus originating xanthophylls. Only two enzymes are necessary for the conversion of beta-carotene into astaxanthin, using several ketocarotenoids as intermediates, in both prokaryotes and eukaryotes. These enzymes are a beta-carotene hydroxylase ( crtZ genes) and a beta-carotene ketolase, encoded by the crtW (bacteria) or bkt (algae) genes.

Animals↗
PubMed2003

Anesthetic technique and development of pneumocephalus after posterior fossa surgery in the sitting position.

OBJECTIVE: Pneumocephalus is a well-known complication of surgical procedures performed with the patients placed in the sitting position. Its incidence and intensity were prospectively studied in 90 consecutive patients undergoing a posterior fossa procedure in this position. Various anesthetic agents, with different effects on cerebral hemodynamics, were used. MATERIAL AND METHODS: Patients were randomly assigned to one of three groups. In group 1 (n=30), anesthesia was induced and maintained with propofol. In group 2 (n=30), anesthesia was induced with thiopental and maintained with isoflurane. In group 3 (n=30), anesthesia was induced with thiopental and maintained with nitrous oxide and low-dose isoflurane. All patients received a load dose and an infusion of fentanyl. A cerebral computed tomography scan was performed to all patients 8 hours after surgery for detecting the presence and location of intracranial air. The size of pneumocephalus was ascertained using the formula for calculating the volume of a spheroid: v = PI / 6. x. y. z. Preoperative diagnosis, existence of shunted or non-shunted hydrocephalus, type and duration of the surgical procedure, detection of intraoperative venous air embolism, and appearance of new neurological symptoms in the postoperative period, were recorded. RESULTS: All patients included in the study developed postoperative pneumocephalus. There were no significant differences (P = 0.133) in the estimated volume of intracranial air between the groups (group 1, volume = 38.3 -/+ 35.4 ml; group 2, volume = 48.9 -/+ 36.3 ml; group 3, volume = 31.5 -/+ 28.4 ml). Only two patients in the group 2 manifested symptoms of neurological involvement due to the pressure exerted by the intracranial air. CONCLUSIONS: Despite the hypothetical diverse effects of the three anesthetic techniques used in this series on cerebral hemodynamics, our results suggest that none of them has a substantial effect on the amount of intracranial air detected after posterior fossa procedures performed in seated individuals. To the best of our knowledge this is the first report that addresses in a prospective manner the effects of several habitual anesthetic techniques on the development of pneumocephalus in patients submitted to posterior fossa procedures performed in the sitting position.

Adolescent↗
PubMed2003

Heterologous expression of the Saccharomyces cerevisiae PGU1 gene in Schizosaccharomyces pombe yields an enzyme with more desirable properties for the food industry.

The Saccharomyces cerevisiae PGU1 gene was successfully expressed in Schizosaccharomyces pombe. The optimum pH and temperature for the recombinant enzyme were 5 and 40 degrees C, respectively, these being around 0.5 U higher and 5 degrees C lower than those shown by the native enzyme. The K(m) value was about fourfold higher than that of the S. cerevisiae enzyme. The recombinant endopolygalacturonase was more efficient in reducing the viscosity of polygalacturonic acid and was also more stable at different pHs and temperatures than the native enzyme.

Culture Media↗
PubMed2002

[Ventriculopleural shunt to treat hydrocephalus].

INTRODUCTION: Ventriculoatrial and ventriculopleural shunts (VPS) are alternatives to ventriculoperitoneal shunts for draining cerebrospinal fluid from patients with hydrocephalus. VPS has seldom been used because of the risk of respiratory insufficiency due to pneumothorax or pleural effusion. However, valves are currently available with anti-siphon devices for use with standard shunting systems to prevent the development of pleural effusion. The aim of this study was to analyze outcome after VPS in eight patients in whom we used the new valves for avoiding overdrainage of cerebrospinal fluid. MATERIAL AND METHOD: Nine VPS procedures were performed in eight hydrocephalic patients between 1988 and 2000. We used differential pressure valves in eight procedures and a flow regulator valve in one. The externally adjustable Sophy valve was used in six cases. The indication for VPS was peritoneal adhesions in four cases, persistent ascites in two, ventriculoatrial valve obstruction in one, and infection of the peritoneal shunt (peritonitis) in one. The ninth case involved replacement of a previously obstructed valve. RESULTS: After a follow-up period of 22 months all shunts were functioning well and the only patient with symptoms of hydrocephalus was the one who required valve replacement at six months. No surgical morbidity or mortality was observed, and only one patient developed transitory signs of excessive cerebrospinal fluid drainage, which was corrected by regulating the magnetic valve gradient. The death of one patient 36 months after surgery was unrelated to pleural drainage. CONCLUSIONS: Valves newly designed to prevent overdrainage of cerebrospinal fluid give satisfactory results, such that VPS should be considered as an alternative to peritoneal drainage.

Adolescent↗
PubMed2002

Medulloblastomas in neurofibromatosis type 1. Case report and literature review.

A 6-year-old girl, previously diagnosed with neurofibromatosis type 1 (NF-1) presented with ataxia and symptoms of raised intracranial pressure. Diagnostic work up disclosed a posterior fossa tumor. Histopathological study of the excised neoplasm showed a cerebellar medulloblastoma. We review the current literature and suggest that the association of medulloblastoma with NF-1 is not a chance occurrence, and that it might be pathogenically related. We propose that medulloblastoma should be added to the list of malignancies that are apt to occur in NF-1.

Ataxia↗
PubMed2001

Atlanto-axial rotatory subluxation in children: early management.

Atlanto-axial rotatory subluxation (AARS) is an uncommon condition involving dislocation and abnormal fixation of the atlas on the axis. AARS is difficult to diagnose and if improperly treated it may lead to permanent neck deformity. We report a retrospective series of patients diagnosed with AARS seen during the last five years. The children presented with neck pain, head tilt, and reduction in neck mobility. In three of the cases the condition was secondary to cervical trauma and in the fourth it was associated with otitis (Grisel syndrome). The diagnosis was established by three-dimensional computerised tomography. In three cases, the atlanto-axial fixation was cured after cervical immobilisation and physiotherapy. A posterior cervical fusion was required in the remaining case. Early detection and intensive conservative treatment constitutes the mainstay of management of AARS. Surgery is reserved for cases with irreducible or recurrent subluxation.

Adolescent↗
PubMed2001

Lumbar canal stenosis: a cause of late neurological deterioration in patients with spina bifida.

BACKGROUND: Patients diagnosed with spina bifida may show late deterioration. This worsening in their clinical symptoms has been attributed to a multiplicity of causes such as secondary tethering of the spinal cord, Chiari II anomaly, hydromyelia, diastematomyelia, arachnoid cysts, and dermoid tumors. METHODS: We searched the clinical records of patients diagnosed with spina bifida who were treated at our hospital for a period of 25 years for the purpose of ascertaining the number and etiology of cases of late neurological deterioration. RESULTS: Six of 144 patients with open spina bifida presented with late neurological deterioration. In one of these cases and in another patient with occult spina bifida the most relevant factor noted during surgery was the presence of marked lumbar canal stenosis. CONCLUSION: We suggest that certain cases of late clinical worsening in spina bifida patients are because of lumbar canal stenosis and that this condition should be added to the list of causes that may produce delayed neurological deterioration in patients with spinal dysraphism.

Adult↗