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Biomedical subjects

A Fernández

Publications and source records attributed to A Fernández.

At least 19 recordsLinked to original sources
PubMed1997

The motif V of plum pox potyvirus CI RNA helicase is involved in NTP hydrolysis and is essential for virus RNA replication.

The plum pox potyvirus (PPV) protein CI is an RNA helicase whose function in the viral life cycle is still unknown. The CI protein contains seven conserved sequence motifs typical of RNA helicases of the superfamily SF2. We have introduced several individual point mutations into the region coding for motif V of the PPV CI protein and expressed these proteins in Escherichia coli as maltose binding protein fusions. Mutations that abolished RNA helicase activity also disturbed NTP hydrolysis. No mutations affected the RNA binding capacity of the CI protein. These mutations were also introduced in the PPV genome making use of a full-length cDNA clone. Mutant viruses carrying CI proteins with reduced RNA helicase activity replicated very poorly in protoplasts and were unable to infect whole plants without rapid pseudoreversion to wild-type. These results indicate that motif V is involved in the NTP hydrolysis step required for potyvirus RNA helicase activity, and that this activity plays an essential role in virus RNA replication inside the infected cell.

Adenosine Triphosphatases↗
PubMed1997

Cell-cell adherence as a selection method for the generation of anti-melanoma monoclonal antibodies.

The aim of the present study was to obtain monoclonal antibodies (mAbs) recognising human melanoma-associated antigens after immunisation of BALB/c mice with a 70-150 kDa membrane fraction from melanoma tumour tissues. Screening of specific antibody- producing hybridomas was performed using a novel cell-cell adherence method with the melanoma cell line M-14. Three mAbs of IgG1 isotype were selected: Mel-1, Mel-2 and Mel-3 which recognised the immunogen by ELISA and stained several melanoma cell lines positive in immunofluorescence. The molecular weight of the antigen was studied by different methods; a 170-kDa band was identified following immunoblotting of tumour lysate and a 72-kDa band was observed following immunoaffinity purification. Cell-cell adherence appears to be a reliable procedure for the generation of mAbs against native cellular antigens.

Animals↗
PubMed1997

Dramatic saccharide-mediated protection of chaotropic-induced deactivation of concanavalin A.

This work provides evidence of a physical instance in which some proteins that are usually inactivated under strong chaotropic conditions may become fully resistant through the occupancy of their binding sites with suitable ligands. In this regard, we found that Moluccella laevis lectin remains stable in the presence of denaturant concentrations of urea when an appropriate saccharide is bound to the protein (Alperin, D.M., Latter, H., Lis, H., and Sharon, N. (1992) Biochem. J. 285, 1-4). Extending this finding, we now demonstrate that the occupancy of the ligand binding sites of concanavalin A (Con A) with appropriate carbohydrates completely prevents the denaturation course elicited by 8 M urea at pH 7.4. In addition, the protecting efficiency of the saccharides was shown to be directly related to their specificities for the lectin. The observed saccharide protection follows the order:methyl alpha-D-mannopyranoside > methyl alpha-D-glucopyr-anoside > mannose > fructose > glucose. Concomitantly, the active tetrameric lectin with a molecular mass of approximately 105 kDa is preserved in 8 M urea when methyl alpha-D-mannopyranoside (100 mM) is present in the medium.

Allosteric Regulation↗
PubMed1997

[An epidemiological and social study of 127 patients with AIDS IN Aragon].

OBJECTIVE: To evaluate the profile epidemiology and social of the patient with AIDS in our environment and the direct relation with primary care. DESIGN: A descriptive, analytic and retrospective study. SETTING: The study was carried out in the Miguel Servet Hospital in Zaragoza. PARTICIPANTS: Patients with AIDS between January 1991 and june 1993 and who fulfilled the requisite diagnostic criteria. MEASUREMENTS AND MAIN RESULTS: Out of the 127 patients studied, 74.8% were male and the age was 20 to 30 years old. The transmission mechanism was blood way in drug addicts in 63.8% and heterosexual way in 14.8%. It was socioeconomic problems in 40.94%, and 69.23% of them were drug addicts. The familiar support were proved in 29.13% and had relation with primary care only 15.74%. CONCLUSIONS: An increase of the incidence of AIDS is observed, prevailing men between 31-40 years old. The heterosexual way transmission is increasing, but the blood way in drug addicts is more frequently. The majority presents socioeconomic problems and they haven't familiar support.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Localization of NADPH-diaphorase containing neurons in the spinal dorsal horn and spinal sensory ganglia of the turtle Chrysemys d'orbigny.

NADPH-diaphorase positive (NDP) neurons and nerve fibers were found in the spinal dorsal horn (DH) and sensory ganglia of the turtle Chrysemys d'orbigny. Three well-defined types of NDP neurons were found in the DH: (a) elongated nerve cells with two radially arranged dendritic branches, (b) neurons with rostrocaudal dendritic branches, (c) bitufted neurons with two, practically symmetric branches that project to the ipsilateral and contralateral dorsal horns. A combination of the techniques that reveal NADPH-diaphorase activity with the horseradish peroxidase transganglionic labeling of the dorsal root collaterals, suggested that NDP neurons of the DH are second-order cells of the spinal sensory pathway. NDP neurons were also found in the spinal sensory ganglia at all metameric levels. Our findings indicate that the DH of turtles, like that of mammals, contains both the enzymatic machinery and the neural connections required to postulate the participation of nitric oxide in "plastic phenomena" such as hyperalgesia and central sensitization. Two other alternatives or complementary hypotheses are discussed: (a) NDP neurons in the DH and sensory ganglia may represent specific cell populations involved in the processing of sensory visceral information; (b) NADPH-diaphorase reactivity may indicate sustained levels of neuronal activity.

Afferent Pathways↗
PubMed1997

Adherence of Staphylococcus aureus slime-producing strain variants to biomaterials used in orthopaedic surgery.

The adherence of Staphylococcus aureus to biomaterials used in orthopaedic surgery (polymethylmethacrylate, fresh bone, steel and titanium alloys) and to glass was studied in vitro at 1, 2, 6, 24 and 48 h of incubation. Nonslime-producing strains (72, 80 and 510) and slime-producing variants of these strains were used. An automated and fast method of ATP-bioluminiscence was applied to determine bacterial viability. The lowest adherence corresponded to polymethylmethacrylate and bone, and the highest to metals. Significant adherence was detected in all cases after 6 h and was strain dependent, being lowest for strain 72. In most cases, adherence of nonslime-producing variants was not significant compared with controls, and slime-producing were more adherent than nonslime-producing variants. These differences were maximal at 6 h or 48 h, depending on the strain and the material. The findings suggest that the appearance of slime-producing cells within a given nonslime-producing bacterial population may jeopardise postoperative immune systems and antibiotic efficacy as a consequence of biofilm formation on implants and prostheses.

Analysis of Variance↗
PubMed1997

Bacteria associated with enzootic pneumonia in goats.

A histological and microbiological study of lung samples from 83 slaughtered goats (33 kids and 50 adults) drawn from a flock with a history of pleuropneumonia caused by mycoplasmas of the M. mycoides group was carried out. A total of 82% (27/33) of kids and 36% (18/50) of adult goats presented pulmonary lesions characteristic of enzootic pneumonia: lesions took the form of bronchointerstitial pneumonia with peribronchial and peribronchiolar proliferation of lymphocytes. Microbiological analysis confirmed a range of mycoplasma species, including Mycoplasma mycoides ssp. mycoides Large Colony (MmmlC) (3.70%; 1/27), Mycoplasma mycoides ssp. capri (Mmc) (7.40%; 2/27), Mycoplasma putrefaciens (22.2%; 6/27), Mycoplasma arginini (3.70%; 1/27) and Mycoplasma sp. (7.40%; 2/ 27), as well as Pasteurella multocida (14.8%; 4/27), associated with enzootic pneumonia lesions in younger animals, whereas Mycoplasma sp. was associated with enzootic pneumonia in adult goats (22.0%; 4/18). Cilia-associated respiratory (CAR) bacillus found by histochemical examination was associated with enzootic pneumonia in kids (25.9%; 7/27) and goats (44.4%; 8/18), being the first description of this bacterium in adult goats.

Animals↗
PubMed1997

Natural cilia-associated respiratory bacillus infection in rabbits used for elaboration of hyperimmune serum against Mycoplasma sp.

Cilia-associated respiratory (CAR) bacillus was identified in lung lesions of rabbits used for elaboration of hyperimmune serum against Mycoplasma mycoides ssp. capri (Mmc). Numerous Warthin Starry (WS) positive filamentous bacteria aligned perpendicularly to the surface of bronchial epithelial lining were observed. Immunoperoxidase staining of these bacteria was detected using a serum anti-rabbit CAR bacillus. Ultrastructural morphology corresponds to that of CAR bacilli previously reported in rabbits. The desirability of monitoring laboratory rabbits for CAR bacillus infection as part of the health programme is reinforced, especially in rabbits used for raising sera against respiratory pathogens of animal species in which CAR bacillus infection has been described. This is the first report of natural CAR bacillus infection in rabbits in Europe.

Animals↗
PubMed1997

The role of verb tense and verb aspect in the foregrounding of information during reading.

In three experiments, we explored the role of verb tense and verb aspect in subjects' construction of mental models while reading. In the first and second experiments, subjects read paragraphs in which verb tense was manipulated to assign current and past attributes (job descriptions) to a main character. The results showed that on-line accessibility was faster for current attributes. The results of the third experiment showed that verb aspect manipulations regarding character actions affect the speed at which the characters are available for recognition.

Humans↗
PubMed1997

[Surgical treatment of tertiary hyperparathyroidism in childhood].

Parathyroid surgery among pediatric population is an exceptional event. Sometimes, chronic renal failure cause independent and uncontrolled parathyroid overfunction; in this situation, a pediatric surgeon may be required. We report herein three kidney transplant patients who were diagnosed of tertiary hyperparathyroidism. Medical treatment didn't control the disease, so total parathyroidectomy with autotransplant in the forearm was indicated. The two patients who underwent surgery are free of the disease with a follow-up period of 6 and 26 months respectively. The other patient died a few days before the operation.

Adolescent↗
PubMed1997

Tracheal malformation in a bicephalic Honduran milk snake (Lampropeltis hondurensis) and subsequent fatal Salmonella arizonae infection.

A bicephalic Honduran milk snake (Lampropeltis hondurensis) with tracheal duplication and malformation and Salmonella arizonae infection is described. There were atypically wide collapsed tracheal rings with necrotizing tracheitis and abundant necrotic epithelial debris and inflammatory cells obstructing the lumen in one of the duplicate tracheae. Salmonella arizonae was cultured from the malformed duplicate trachea and was considered to be the etiologic agent causing necrosis.

Animals↗
PubMed1996

Sequentially folded SV-11 RNA: metastability is relevant to biological function.

By simulating a Markov process comprising kinetically controlled elementary chain-growth steps and upstream refolding events, we compute the sequential folding of SV-11 RNA; a species capable of acting as a template instructing its own replication when folded into a metastable conformation. The predicted structure is endowed with available primers for replication and is identical within the regions of homology to the experimentally probed active structure of MNV-11 RNA, a species from which SV-11 RNA has evolved. The uneven rate of chain growth during SV-11 RNA replication and the pause sites along the replica sequence are determined. Such predictions are testable in pulse-chase kinetic experiments.

Base Sequence↗
PubMed1996

African swine fever: morphopathology of a viral haemorrhagic disease.

Twelve miniature pigs were infected experimentally with the moderately-virulent Spanish isolate of African swine fever virus E75. The disease was reproduced acutely and subacutely, and six days after infection the animals showed severe clinical and pathological signs characterised by diffuse haemorrhages in lymphoid and non-lymphoid organs. An immunohistopathological study, using two different methods, and a monoclonal antibody (mAb) (18BG3) were used to analyse the distribution of the virus protein 73 (VP73) and IgM and IgG. VP73 was observed primarily in cells of the mononuclear phagocyte system, and in many megakaryocytes, some tubular epithelial cells of the kidneys, tonsillar epithelium, some hepatocytes, and in a few endothelial cells and neutrophils in the later stages of the infection. The histological findings and the distribution of VP73 and IgM and IgG indicated that the virus caused haemorrhagic lesions through its effect on various haemostatic mechanisms.

African Swine Fever↗
PubMed1996

Magnesium-aided folding of group I ribozymes with a minimal loss of entropy.

The aim of this work is to quantify, rationalize and incorporate the effect of Mg(II) ions on the kinetic barriers of entropic origin associated to RNA folding events in vitro. This study encompasses the scaffolding effect of Mg(II) upon the formation of the pseudoknot structural motif which is believed to be crucial for shaping the catalytic core of group I ribozymes. Our results are contrasted with recent experimental probes on folding kinetics. The first set of objectives is accomplished by determining the participation of Mg(II) in the reduction of the conformational entropy cost during folding. First, the dominant contribution to conformational entropy loss associated to loop closure is obtained. The derivation hinges upon the notion that loop closure entails the formation of an inner and outer solvent domain and backbone phosphate groups orient themselves concurrently towards the best dielectric environment. At this point, the role of Mg(II) ions can be assessed by taking into account that Mg(II) coordinates with two adjacent backbone phosphates in unpaired regions. Thus, for a small loop of even length, the energy decrease due to coordination reduces the conformational entropy loss due to phosphate orientation by one half. In the case of pseudoknot formation, the orientational effect prevents the coplanarity of the loops comprising the pseudoknot and allows us to determine the kinetic barrier associated to its formation in the presence of magnesium. Incorporating these facts to kinetically controlled Monte Carlo simulations, we find that the predicted folding pathway for group I introns leads to the phylogenetically inferred secondary structures and allows us to elucidate the magnesium-dependent rate-limiting step in the formation of the P3-P7 pseudoknotted region of the catalytic core.

Base Sequence↗
PubMed1996

Pneumococcal pyomyositis. Case report, review of the literature, and comparison with classic pyomyositis caused by other bacteria.

Pyomyositis is caused by staphylococci in 70% to 90% of patients. We report a case of pneumococcal pyomyositis (PP), review the 11 cases previously published, and compare the features of pneumococcal pyomyositis with those of classic (nonpneumococcal) pyomyositis. Several clinical characteristics have been identified that are notably different in both groups. Psoas muscle involvement was observed in two thirds of the patients with PP, and a source for the infection was identified in half of the patients. Patients with PP were older than those with classic pyomyositis. Men were affected less often than women with PP, but the opposite was the rule in classic pyomyositis. The systemic response to the infection was more prominent in patients infected with pneumococci than from other causes. Most patients with PP were successfully treated with antibiotics and drainage. Secondary meningitis was observed in 3 patients with psoas muscle abscess caused by pneumococci. Mortality is low in pyomyositis regardless of the causative pathogen.

Aged↗