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Biomedical subjects

A Martins

Publications and source records attributed to A Martins.

At least 19 recordsLinked to original sources
PubMed2002

Clinical profiles relating gender and depressive symptoms among adolescents ascertained by the Beck Depression Inventory II.

PURPOSE: Depressive disorders (DD) in adolescence are often misdiagnosed and under-recognised. A major clinical problem regards the high rate of co-morbidity with other disorders, namely substance abuse. The aim of this study was to assess the discriminative power of the Beck Depression Inventory II (BDI-II) to characterise specific social-demographic variables related to DD in adolescence. METHODS: A Portuguese version of the BDI-II and a social-demographic questionnaire were administered to 775 Portuguese adolescents (312 males, 463 females; mean age: 16.9 years); 83 adolescents performed a clinical interview following DSM-IV criteria. RESULTS: Mean BDI-II Portuguese version (BDI-II-P) total score was 10.31 (standard deviation: 8.4), with females reporting more depressive symptoms than males (P < 0.001). Low academic achievement, sleep disturbances, and alcohol consumption were consistently associated with depressive symptoms for both genders. Higher tobacco consumption was significantly associated with depressive symptoms in females. Familial factors did not appear to be associated with depressive symptoms in males. However, a higher frequency of siblings, having separated parents as well as a more extreme perception of the mother's educational style were consistently associated with depressive symptoms in females. CONCLUSION: The BDI-II-P showed discriminative power to characterise social-demographic variables related to DD especially in adolescent females.

Adolescent↗
PubMed2002

The importance of pets as reservoirs of resistant Enterococcus strains, with special reference to vancomycin.

The purpose of the present study was to determine the prevalence of antibiotic resistance, with special attention to vancomycin, in 104 strains of Enterococcus, which is the sentinel bacterium isolated from dog and cat faeces samples. The phenotypic characterization of the isolates classified them as E. faecium (58%), E. avium (41%) and E. faecalis (1%). Sensitivity testing used the diffusion method according to the recommendations of CASFM (Comite de l'Antibiogramme de la Société Française de Microbiogie), to oxacillin, amoxycillin, amoxycilin + clavulanic acid, ampicillin, piperacillin, cefoperazone, imipenem, enrofloxacin, ciprofloxacin, ofloxacin, nalidixic acid, tetracycline, lincomycin, erythromicin and vancomycin. Minimum inhibitory concentration (MIC) determination by E test revealed a MIC to vancomycin of between 0.5 microg/ml and 3 microg/ml. All the strains were resistant to nalidixic acid, erythromycin, cefoperazone and oxacillin. We detected resistance to amoxycillin + clavulanic acid in 1.9% of isolates, to amoxycillin in 4.8%, to piperacillin in 13.5%, and to ampicillin in 21.2% of strains. A high prevalence of antibiotic resistance to lincomycin, tetracycline, enrofloxacin, ciprofloxacin and ofloxacin was found in 98.1%, 95.2%, 76.9%, 73.1% and 64.4% of strains, respectively. Resistance to vancomycin was not found, which indicates that there is no transmission risk of vancomycin-resistant enterococcal strains to man or transfer of their resistance genes to other bacteria belonging to the endogenous flora of humans.

Animals↗
PubMed2001

Mutational analysis of baculovirus capping enzyme Lef4 delineates an autonomous triphosphatase domain and structural determinants of divalent cation specificity.

The 464-amino acid baculovirus Lef4 protein is a bifunctional mRNA capping enzyme with triphosphatase and guanylyltransferase activities. The hydrolysis of 5'-triphosphate RNA and free NTPs by Lef4 is dependent on a divalent cation cofactor. RNA triphosphatase activity is optimal at pH 7.5 with either magnesium or manganese, yet NTP hydrolysis at neutral pH is activated only by manganese or cobalt. Here we show that Lef4 possesses an intrinsic magnesium-dependent ATPase with a distinctive alkaline pH optimum and a high K(m) for ATP (4 mm). Lef4 contains two conserved sequences, motif A ((8)IEKEISY(14)) and motif C ((180)LEYEF(184)), which define the fungal/viral/protozoal family of metal-dependent RNA triphosphatases. We find by mutational analysis that Glu(9), Glu(11), Glu(181), and Glu(183) are essential for phosphohydrolase chemistry and likely comprise the metal-binding site of Lef4. Conservative mutations E9D and E183D abrogate the magnesium-dependent triphosphatase activities of Lef4 and transform it into a strictly manganese-dependent RNA triphosphatase. Limited proteolysis of Lef4 and ensuing COOH-terminal deletion analysis revealed that the NH(2)-terminal 236-amino acid segment of Lef4 constitutes an autonomous triphosphatase catalytic domain.

Acid Anhydride Hydrolases↗
PubMed2001

Structure and mechanism of the RNA triphosphatase component of mammalian mRNA capping enzyme.

The 5' capping of mammalian pre-mRNAs is initiated by RNA triphosphatase, a member of the cysteine phosphatase superfamily. Here we report the 1.65 A crystal structure of mouse RNA triphosphatase, which reveals a deep, positively charged active site pocket that can fit a 5' triphosphate end. Structural, biochemical and mutational results show that despite sharing an HCxxxxxR(S/T) motif, a phosphoenzyme intermediate and a core alpha/beta-fold with other cysteine phosphatases, the mechanism of phosphoanhydride cleavage by mammalian capping enzyme differs from that used by protein phosphatases to hydrolyze phosphomonoesters. The most significant difference is the absence of a carboxylate general acid catalyst in RNA triphosphatase. Residues conserved uniquely among the RNA phosphatase subfamily are important for function in cap formation and are likely to play a role in substrate recognition.

Acid Anhydride Hydrolases↗
PubMed2001

Structural characterisation of flavonoids and flavonoid-O-glycosides extracted from Genista tenera by fast-atom bombardment tandem mass spectrometry.

Genista tenera is a plant native to the Madeira Island (Portugal). From the ethanol extract of its powdered aerial parts, two flavones, three isoflavones and one 7-O-glucosyl isoflavone were isolated. A mass spectrometric study of these compounds was performed using liquid secondary ion mass spectrometry (LSIMS) in combination with high-energy collision-induced dissociation (CID) and tandem mass spectrometry (MS/MS). Characteristic fragmentation patterns were observed in all the investigated compounds; the loss of small neutral species from the protonated molecules was useful for identifying the presence of specific functional groups in the A- and B-rings. In order to help to establish the proposed structures, NMR and UV studies were also performed.

Flavonoids↗
PubMed2001

Landfarming in a PAH-contaminated soil.

The present work describes a coke oven soil treatability study by land-farming, conducted on-site in a field scale facility covering 100 m2. The soil contamination was mainly due to high concentrations of polynuclear aromatic hydrocarbons (PAHs) up to 1,140 mg/Kg dry weight (sigma EPA). Along the treatment process the soil was characterised at the chemical, microbiological and ecotoxicological levels. After 3 months a reduction of 63% in total PAHs concentration was observed, being detected a more pronounced reduction for PAHs with 2, 3 and 4 rings (79%). Concomitantly, a change in the composition of the microbial population was observed with a significant increase in the PAHs degrading and total heterotrophic colonies. Concerning the ecotoxicity and genotoxicity data no effect was detected in the treated soil samples eluates.

Biodegradation, Environmental↗
PubMed2001

Effects of culture system and protein supplementation on mRNA expression in pre-implantation bovine embryos.

Assisted reproduction technologies have made great progress during the last 15 years in most mammalian species, including humans. Growing evidence indicates that bovine pre-implantation development is a superior model for investigating early human development than the mouse. The purpose of this study was to investigate the effects of two basic culture systems [tissue culture medium (TCM) with 5% CO(2) in air or synthetic oviduct fluid (SOF) with 7% O(2), 88% N(2,) 5% CO(2)] and various protein supplements (serum, bovine serum albumin or polyvinyl alcohol) on the relative abundance of a set of developmentally important gene transcripts in bovine morulae and blastocysts and to compare the results with those for their in-vivo-derived counterparts. The basic culture system including the basic medium composition and oxygen tension had profound effects on the amounts of specific transcripts in bovine embryos, whereas the 'protein source' had only weak effects. Significant differences (P < or = 0.05) in the relative abundance of specific gene transcripts were detected between in-vivo and in-vitro-derived embryos, especially at the morula stage. More differences were found between embryos produced in the TCM system and in-vivo-derived embryos than between SOF-generated embryos and their in-vivo counterparts. No differences were found in the relative abundance of gene transcripts in embryos generated under chemically defined conditions in the two different laboratories. It is concluded that the SOF system provides an environment in which pre-implantation development of bovine embryos is more similar to that occurring in vivo than in the TCM system.

Animals↗
PubMed2001

The distally based island superficial sural artery flap: clinical experience with 36 flaps.

The principles of neurocutaneous flaps, first described by Masquelet in 1992, represented a new concept in skin vascularization. The distally based superficial sural artery flap is an example of this kind of flap, which is supplied by the vascular axis that accompanies the sural nerve. The authors treated 36 patients with 36 distally based superficial sural artery flaps. All flaps survived, but six of them exhibited partial necrosis. No patient experienced anesthesia of the lateral side of the foot or neuroma at the donor site 12 months after surgery. The authors confirmed that this flap is very useful for soft-tissue reconstruction of the distal third of the leg and foot. Additionally they conclude that the principal advantages are that the blood supply is reliable, execution is easy and fast, the operation can be performed under regional anesthesia, the flap has a large arc of rotation, direct closure of the donor area is possible for small flaps, major arteries or nerves are not sacrificed, and excellent durability is achieved, even on weight-bearing areas. The major drawback is the donor site scar.

Adolescent↗
PubMed2000

Mechanism of phosphoanhydride cleavage by baculovirus phosphatase.

Baculovirus phosphatase (BVP) is a member of the metazoan RNA triphosphatase enzyme family that includes the RNA triphosphatase component of the mRNA capping apparatus. BVP and other metazoan RNA triphosphatases belong to a superfamily of phosphatases that act via the formation and hydrolysis of a covalent cysteinyl-phosphate intermediate. Here we demonstrate the formation of a BVP phosphoenzyme upon reaction with [gamma-(32)P]ATP and identify the linkage as a thiophosphate based on its chemical lability. We surmise that the phosphate is linked to Cys(119) of BVP because replacement of Cys(119) by alanine or serine abrogates phosphoenzyme formation and phosphohydrolase activity. The catalytic cysteine is situated within a conserved phosphate-binding loop ((118)HCTHGINRTGY(128)). We show that all of the non-aliphatic side chains of the phosphate-binding loop are functionally important, insofar as mutants H118A, H121A, N124A, R125A, T126A, and Y128A were inactive in gamma phosphate hydrolysis and the T120A mutant was 7% as active as wild-type BVP. Structure-activity relationships at the essential positions of the phosphate-binding loop were elucidated by conservative substitutions. A conserved aspartic acid (Asp(60)) invoked as a candidate general acid catalyst was dispensable for phosphohydrolase activity and phosphoenzyme formation by BVP. We propose that the low pK(a) of the bridging oxygen of the beta phosphate leaving group circumvents a requirement for expulsion by a proton donor during attack by cysteine on the gamma phosphorus. In contrast, a conserved aspartic acid is essential for the phosphomonoesterase reactions catalyzed by protein phosphatases, where the serine or tyrosine leaving groups have a much higher pK(a) than does ADP.

Adenosine Diphosphate↗
PubMed2000

Surgical clips as a nidus for stone formation in the common bile duct.

We report the case of a 40-year-old woman who presented with symptomatic gallbladder stones. A laparoscopic cholecystectomy was performed using metallic clips. Three years later, she underwent a endoscopic retrograde cholangiopancreatography (ERCP) for interscapular and right upper quadrant pain, jaundice, and fever. This examination revealed a stone and clips in the common bile duct (CBD). A sphinteroctomy was undertaken, but the stone could not be extracted despite multiple attempts. Ultimately, a Kocher incision was required to achieve choledocotomy and extraction of the stone and the clips.

Adult↗
PubMed2000

Multifocal pattern electroretinogram does not demonstrate localised field defects in glaucoma.

PURPOSE: To determine if a multifocal PERG could be recorded in normals, and to examine changes in the multifocal PERG in glaucoma patients. To compare the ability of multifocal PERG and multifocal VEP responses in the same individuals to identify localised field defects in glaucoma. METHODS: Using the VERIS Scientific system multifocal PERGs were recorded from 19 sites of the visual field according to pseudo-random binary m-sequence. Twenty normals and 15 glaucoma subjects were tested. Multifocal pattern VEPs were also recorded in the glaucoma cases using a cortically scaled stimulus. RESULTS: The second order kernel of the PERG shows a consistent signal. The overall PERG amplitude decreases with age in normals. In glaucoma the PERG amplitude was reduced across the field, but reductions did not correspond to the area of the scotoma. The VEP showed localised signal reductions in all 15 cases of glaucoma. CONCLUSION: A multifocal PERG can be recorded in normals. However it did not reflect localised ganglion cell losses, whereas the multifocal pattern VEP recorded to a very similar stimulus in the same individual did show losses in the scotoma area.

Adult↗
PubMed2000

A yeast-based genetic system for functional analysis of viral mRNA capping enzymes.

Virus-encoded mRNA capping enzymes are attractive targets for antiviral therapy, but functional studies have been limited by the lack of genetically tractable in vivo systems that focus exclusively on the RNA-processing activities of the viral proteins. Here we have developed such a system by engineering a viral capping enzyme-vaccinia virus D1(1-545)p, an RNA triphosphatase and RNA guanylyltransferase-to function in the budding yeast Saccharomyces cerevisiae in lieu of the endogenous fungal triphosphatase (Cet1p) and guanylyltransferase (Ceg1p). This was accomplished by fusion of D1(1-545)p to the C-terminal guanylyltransferase domain of mammalian capping enzyme, Mce1(211-597)p, which serves as a vehicle to target the viral capping enzyme to the RNA polymerase II elongation complex. An inactivating mutation (K294A) of the mammalian guanylyltransferase active site in the fusion protein had no impact on genetic complementation of cet1Deltaceg1Delta cells, thus proving that (i) the viral guanylyltransferase was active in vivo and (ii) the mammalian domain can serve purely as a chaperone to direct other proteins to the transcription complex. Alanine scanning had identified five amino acids of vaccinia virus capping enzyme-Glu37, Glu39, Arg77, Glu192, and Glu194-that are essential for gamma phosphate cleavage in vitro. Here we show that the introduction of mutation E37A, R77A, or E192A into the fusion protein abrogates RNA triphosphatase function in vivo. The essential residues are located within three motifs that define a family of viral and fungal metal-dependent phosphohydrolases with a distinctive capacity to hydrolyze nucleoside triphosphates to nucleoside diphosphates in the presence of manganese or cobalt. The acidic residues Glu37, Glu39, and Glu192 likely comprise the metal-binding site of vaccinia virus triphosphatase, insofar as their replacement by glutamine abolishes the RNA triphosphatase and ATPase activities.

Acid Anhydride Hydrolases↗
PubMed2000

[CT enteroclysis for detection of small bowel tumors].

PURPOSE: To assess the feasibility and the usefulness of CT enteroclysis (helical CT with enteroclysis) in detecting small bowel tumors. MATERIALS AND METHODS: Fifty patients were referred for suspicion of small bowel tumor. CT enteroclysis is performed by injecting a large volume of water using a pomp through a nasojejunal tube followed by a thin section helical acquisition. RESULTS: Forty-eight helical CT enteroclysis were performed in order to detect 25 small bowel tumors. Among them 22 were confirmed by histological study. The mean size of tumors was 23 mm. In 12 of 17 cases, diagnosis was missed or incomplete at conventional barium study. Enteroscopy was performed in 12 of 22 cases, with discordant result in one case and incomplete result in 3 cases. In 8 cases, including 5 carcinoid tumors, patients had surgery after CT enteroclysis only, enteroscopy would probably have not made the diagnosis because the lesions were far from the duodenojejunal junction and ileocaecal valve. CONCLUSION: Helical CT enteroclysis is a new method for detecting small bowel tumors, easy to perform, well tolerated. It seems to be more sensitive than conventional barium studies and less invasive than enteroscopy. Tumor characterization and staging can be performed using a single examination. It seems to be justified to perform CT enteroclysis to detect small bowel tumors or in the evaluation of patients with polyposis.

Adult↗
PubMed2000

[Abdominopelvic ultrasonography in suspected acute appendicitis: prospective study in adults].

STUDY AIM: The aim of this prospective descriptive study was to evaluate the accuracy of abdomino-pelvic ultrasonography in suspected acute appendicitis in adults. PATIENTS AND METHODS: From March to July 1998, 100 consecutive patients, 63 women, 37 men (mean age: 25 years), after examination by a visceral surgeon for suspected acute appendicitis, had an abdominal ultrasonography (US) examination with high frequency transducer (7.5 to 9 MHz). The US examination concerned appendice, periappendicular tissues and neighbouring organs. The US data were correlated with the histopathologic findings in operated on patients, and with the clinical and biological follow up in non operated patients. RESULTS: Fourty-seven patients had acute appendicitis; 53 were operated on and 47 non operated. Analysis of US data revealed sensitivity 91.5%, specificity 94.3%, positive predictive value 93.5%, negative predictive value 94.3%, accuracy 93%; 75% of the other diagnosis were found by US. CONCLUSION: Systematic abdominal ultrasonography in suspected acute appendicitis is recommended in adults.

Abdominal Pain↗
PubMed1999

Mutational analysis of vaccinia virus nucleoside triphosphate phosphohydrolase I, a DNA-dependent ATPase of the DExH box family.

Vaccinia virus nucleoside triphosphate phosphohydrolase I (NPH-I) is a DNA-dependent ATPase that serves as a transcription termination factor during viral mRNA synthesis. NPH-I is a member of the DExH box family of nucleic acid-dependent nucleoside triphosphatases (NTPases), which is defined by the presence of several conserved sequence motifs. We have assessed the contributions of individual amino acids (underlined) in motifs I (GxGKT), II (DExHN), III (SAT), and VI (QxxGRxxR) to ATP hydrolysis by performing alanine scanning mutagenesis. Significant decrements in ATPase activity resulted from mutations at nine positions: Lys-61 and Thr-62 (motif I); Asp-141, Glu-142, His-144, and Asn-145 (motif II); and Gln-472, Arg-476, and Arg-479 (motif VI). Structure-function relationships at each of these positions were clarified by introducing conservative substitutions and by steady-state kinetic analysis of the mutant enzymes. Comparison of our findings for NPH-I with those of mutational studies of other DExH and DEAD box proteins underscores similarities as well as numerous disparities in structure-activity relationships. We conclude that the functions of the conserved amino acids of the NTPase motifs are context dependent.

Acid Anhydride Hydrolases↗
PubMed1998

Pure red cell aplasia due to persistent B19 parvovirus infection in patient infected with human immunodeficiency virus type 1. Recovery with alpha-interferon therapy.

B19 parvovirus (PV) infection is ordinarily resolved with the production of specific antibodies that neutralize virus infectivity for erythroid host cells. Nevertheless persistent infection with B19 PV and pure red blood cell aplasia have been documented. A 27 year-old male. i.v. drug abuser, HIV+ and HCV was diagnosed of pure red cell aplasia. Six months later we had serologic evidence of persistent parvovirus infection. Interferon therapy, started for HCV infection, showed a marked improvement of anaemia and anti parvovirus IgM became negative. It is discussed the possible role of interferon therapy in persistent parvovirus infection.

Adult↗
PubMed1998

[Microsurgical reconstruction of the upper extremity. Experience with 24 free flaps].

The authors present the experience of 24 clinical cases of microsurgical reconstruction of the upper limb. These reconstructions were accomplished by different microvascular free flaps which were selected according to the type, size and location of the defects, having applied fasciocutaneous, adipofascial, myo, myocutaneous, tendofasciocutaneous, omentum flaps and 2nd toe transfers. The etiology was traumatic in 23 cases and tumoral in 1 case. A careful analysis was made for surgical times, selection and survival rate of the free flaps and the morphofunctional quality of the reconstructions. Microvascular free flaps are considered the choice technique for upper limb reconstruction, particularly for the hand in certain defects, considering the better anatomic and functional quality of the reconstructions.

Adolescent↗