A general, PCR-based method for single or combinatorial oligonucleotide-directed mutagenesis on pUC/M13 vectors.
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Base Sequence↗
Biomedical subjects
E Merino
Publications and source records attributed to E Merino.
The role of penicillin amidases in nature and in industry.
Penicillin amidase (PA) is the enzyme used commercially for the production of semisynthetic penicillins. During the past decade, a detailed picture of the structure and regulation of the gene encoding this enzyme has emerged, revealing a variety of interesting features that are unique among microorganisms. Clues to the biological role of this enzyme have been provided, as well as new strategies for the commercial production and utilization of PA.
Escherichia coli↗
Evaluation of the ELISA test for detection of Entamoeba histolytica in feces.
The clinical utility of an ELISA test with monoclonal antibodies to detect antigen of Entamoeba histolytica in feces was evaluated in 150 patients with gastrointestinal symptoms. Each subject was examined by rectosigmoidoscopy with rectal smear and/or a triple stool search for ova-bacteria-parasite (OBP); in addition, one stool sample was collected for the ELISA test. All the tests were independent and double blind. E. histolytica was detected by OBP and/or rectosigmoidoscopy in 66 patients; 61 patients had other parasites; and in 23, no parasites were identified. Of all patients, 116 were positive for the ELISA test. Of these, E. histolytica was identified in 52. In 47, other parasites were identified and in 17, no parasites were found. The ELISA test with a monoclonal antibody against E. histolytica antigen showed higher sensitivity than the standard diagnostic methods: the ability to detect the presence of E. histolytica antigen regardless of the destruction of the parasite or of the error due to misidentification of the parasite resulting from faulty preparation of the samples.
Adolescent↗
Diagnosis of intestinal amebiasis using salivary IgA antibody detection.
This investigation sought to determine whether detection of salivary IgA antibodies to Entamoeba histolytica could identify intestinal amebic infections among 223 school children. Four groups of children were identified through coproparasitoscopic examination: E. histolytica as other parasites only (20%); and parasite-free (25%). The diagnostic accuracy of salivary IgA antibodies to an E. histolytica membrane extract was 91.5% (sensitivity, 85%; specificity, 98%), maintaining high predictive value at different prevalences. Also, a positive correlation (r = .753, P less than .001) was observed between fecal E. histolytica membrane antigen levels and salivary IgA antibody activity. Measurement of IgA antibodies in saliva may be useful in diagnosing intestinal infections with E. histolytica within a wide range of prevalences. Moreover, sampling of saliva may be a useful non invasive test for immunoepidemiologic surveys.
Adolescent↗
[Bacteremic pneumonia caused by Haemophilus influenzae cured with oral erythromycin].
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Administration, Oral↗
The ribonucleoside diphosphate reductase gene (nrdA) of Escherichia coli carries a repetitive extragenic palindromic (REP) sequence in its 3' structural terminus.
A computer search for repeated sequences led us to identify five REP (repetitive extragenic palindromic) sequences in the 3'-terminal region of the Escherichia coli ribonucleoside diphosphate reductase gene (nrdA). These REP sequences are located within a putative duplicated DNA region, the first of them being part of the carboxy-terminal coding region of the nrdA gene. This is the first report of a REP sequence within a structural gene and also the first example of a REP sequence apparently generated by DNA duplication.
Amino Acid Sequence↗
Amino acid sequence analysis of the glutamate synthase enzyme from Escherichia coli K-12.
The amino acid sequence for the two subunits of the glutamate synthase of Escherichia coli K-12 was compared to the protein sequences compiled in the National Biomedical Research Foundation databank. Similarities were detected between the small glutamate synthase subunit and three members of the flavin-containing pyridine nucleotide-disulphide oxidoreductase superfamily, and also with three members of a lactate dehydrogenase family. Two segments in this glutamate synthase subunit showed similarity to regions previously proposed as part of dinucleotide-binding sites in some members of these two families. Similarity can be extended if the predicted secondary structure is considered. Based on these data, residues 148-260 and 289-409 in the small GOGAT subunit are proposed as dinucleotide-binding regions. Comparison of the amino acid sequence of the large glutamate synthase subunit with the glutamine phosphoribosylamine:pyrophosphate phosphoribosyltransferases of B. subtilis and E. coli revealed a significant similarity between the amino termini of these three enzymes. In these last two amidotransferases, the glutamine-binding site has been located in their amino-terminal region. The comparison with a second group of glutamine amidotransferases did not show any significant global similarity with the large glutamate synthase subunit. However, this polypeptide contains a small segment that shares similarity with a 13-amino acid segment proposed as part of the glutamine-binding site in this second group of amidotransferases.
4-Hydroxybenzoate-3-Monooxygenase↗
Deletion of a repetitive extragenic palindromic (REP) sequence downstream from the structural gene of Escherichia coli glutamate dehydrogenase affects the stability of its mRNA.
A deletion that removes one repetitive extragenic palindromic sequence downstream of the structural gene of Escherichia coli glutamate dehydrogenase, reduces twofold the half-life of gdhA mRNA.
Chromosome Deletion↗
Plasmid vector pBR322 and its special-purpose derivatives--a review.
The plasmid pBR322 was one of the first EK2 multipurpose cloning vectors to be designed and constructed (ten years ago) for the efficient cloning and selection of recombinant DNA molecules in Escherichia coli. This 4363-bp DNA molecule has been extensively used as a cloning vehicle because of its simplicity and the availability of its nucleotide sequence. The widespread use of pBR322 has prompted numerous studies into its molecular structure and function. These studies revealed two features that detract from the plasmid's effectiveness as a cloning vector: plasmid instability in the absence of selection and, the lack of a direct selection scheme for recombinant DNA molecules. Several vectors based on pBR322 have been constructed to overcome these limitations and to extend the vector's versatility to accommodate special cloning purposes. The objective of this review is to provide a survey of these derivative vectors and to summarize information currently available on pBR322.
Base Sequence↗
[Spirometric parameters of the working population of young non-smoking males of the Murcia area].
A prospective study on dynamic spirometric parameters on 195 healthy non-smoking men-workers, representing the non-smoking labor population from 16 to 40 years of age, in the Murcia Region (Spain), has been carried out. Men were selected upon two criteria: age and height. Lower normality limits, have been estimated with 95% reliability by developing regression equations for the following spirometric parameters: forced vital capacity, forced expiratory volume (timed and relative), peak flow and forced mid-expiratory flow.
Adolescent↗
Repetitive extragenic palindromic (REP) sequences in the Escherichia coli gdhA gene.
Deletions of the 3' flanking DNA region of the glutamate dehydrogenase (GDH) structural gene from Escherichia coli K-12, have been produced on a plasmid that carries the complete gdhA gene. Those deletions include part of the repetitive extragenic palindromic (REP) sequences proposed by Stern et al. [Cell 37 (1984) 1015-1026], as a novel and major feature of the bacterial genome. The effect of these deletions on the final GDH level in the cell, has been determined. A broader compilation, analysis and alternative functions of the REP sequences, is also presented.
Chromosome Deletion↗
Diaminobenzidine oxidation in cerebellar histological sections.
Cerebellar histological sections were incubated in media containing 3,3'-diaminobenzidine (DAB). Microscopic observation showed the presence of oxidated DAB in all cerebellar cells. Said oxidation of DAB in the cerebellar structures was produced in the absence, as well as in the presence, of exogenous H2O2 in the incubation medium. The erythrocytes existent in the blood vessels were capable of oxidating more intensely the DAB when H2O2 was present in the incubation medium. When the sections were pretreated and incubated with CNK, sodium azide and perodic acid, the oxidation of DAB was not produced. The observation with electron microscope showed that the DAB oxidation is produced in mitochondria, coated vesicles, and lysosomes. The possible mechanisms intervening in the oxidation of DAB in cerebellar structures are discussed.
3,3'-Diaminobenzidine↗
[Electron microscopy of the suprarenal of Didelphys marsupialis. I. Intracytoplasmic microtubular formations in the cortical layer].
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Adrenal Glands↗
New insights on the comma-less theory.
The comma-less hypothesis represents a theoretical effort to describe one of the steps in the early evolution of the translation apparatus. This hypothesis emphasizes the advantages that a RNY coding pattern would have provided in a primitive RNA adaptor-catalyst system. This theory has been debated for years, both in conceptual and statistical terms, and no consensus about its validity has been ascertained. In this work, a statistical model refuting this theory was reconsidered. This new approach eliminates the bias due to the absence of stop codons in the open reading frame, and to the amino acid composition of bacterial genes. The results obtained support the biological significance of the RNY coding pattern.
Amino Acids↗
Peptides and genes coding for scorpion toxins that affect ion-channels.
Most scorpion toxins are ligand peptides that recognize and bind to integral membrane proteins known as ion-channels. To date there are at least 202 distinct sequences described, obtained from 30 different species of scorpions, 27 from the family Buthidae and three from the family Scorpionidae. Toxins that recognize potassium and chloride channels are usually from 29 to 41 amino acids long, stabilized by three or four disulfide bridges, whereas those that recognize sodium channels are longer, 60 to 76 amino acid residues, compacted by four disulfide bridges. Toxins specific for calcium channels are scarcely known and have variable amino acid lengths. The entire repertoire of toxins, independently of their specificity, was analyzed together by computational programs and a phylogenetic tree was built showing two separate branches. The K(+) and Cl(-) channel specific toxins are clustered into 14 subfamilies, whereas those of Na(+) and Ca(2+) specific toxins comprise at least 12 subfamilies. There are clear similarities among them, both in terms of primary sequence and the main three-dimensional folding pattern. A dense core formed by a short alpha helix segment and several antiparallel beta-sheet stretches, maintained by disulfide pairing, seems to be a common structural feature present in all toxins. The physiological function of these peptides is manifested by a blockage of ion passage through the channels or by a modification of the gating mechanism that controls opening and closing of the ion pore.
Amino Acid Sequence↗
Primary esophageal lymphoepithelioma.
Lymphoepitheliomas are extremely rare outside the nasopharynx. Extranasopharyngeal lymphoepithellomas may be located in the stomach or digestive tract, and only one single case of esophageal location has been found in our review. In many cases the tumor is related to Epstein-Barr virus infection. We report a case of undifferentiated carcinoma of the distal third of the esophagus in a 79 year-old man. Pathological examination of the esophagus revealed an undifferentiated carcinoma with lymphold stroma (lymphoepithelioma). In situ hybridization of the neoplastic cells was negative for Epstein-Barr virus. To our knowledge, the present case is the first documented esophageal lymphoepithelioma in Western countries.
Aged↗
[Evaluation of the retention of dental fissure cleft sealants three years after their application to 13-14 year old schoolchildren].
The application of dental cleft sealant in the infant population is an efficient measure in the prevention of occlusal caries and has been adopted by the Program of Infant Dental Attention (Programa de Atención Dental Infantil-PADI) in Navarra. It involves placing a polymerizable resin over the furrows and clefts of the recently emerged and healthy molars. The high levels of retention of the sealant make it possible to preserve the teeth from caries, contributing to a reduction in their incidence. The present descriptive study aims to gain knowledge of and evaluate the permanence of the sealants three years after their application. The work was carried out in 1996 in the Oral Health Service of Navarra on a sample of 160 boys and girls out of a total of 1,372 aged between 16 and 17 years in the Pamplona and Estella health area, who had been treated with cleft sealant at the age of 13-14 years. We found that after 3 years there was retention of the cleft sealant in 39% of those implanted (30% with partial retention and 9% total). In the rest of the sealants (61%) retention was nil. These results differ from those described in other studies in which the percentage of retention is higher. This leads us to affirm the need for revising and improving the technique of application and for carrying out prospective studies for subsequent checks to determine the causes of low retention.
English Abstract↗
[Laryngeal cancer and secondary neoplasms in Murcia].
A retrospective study was made of 428 patients who underwent faryngectomy for cancer of the larynx. Tumor-dependent factors, treatment, and postoperative evolution were analyzed. Total laryngectomy was performed in 74% of cases. The physical examination yielded 19% false negatives and 24.7% false positives. Local recurrence was 12.3% and lymph node recurrence was 9.7%. A second neoplasm was found in 7.8%. The 5-year actuarial recurrence-free rate was 74%.
Humans↗