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M Navajas

Publications and source records attributed to M Navajas.

33 records · Page 2Linked to original sources
PubMed1996

Mitochondrial COI sequences in mites: evidence for variations in base composition.

Studies of mitochondrial DNA sequences in a variety of animals have shown important differences between phyla, including differences in the genetic codes used, and varying constraints on base composition. In that respect, little is known of mites, an important and diversified group. We sequenced a portion (340 nt) of the cytochrome oxidase subunit I (COI) encoding gene in twenty species of phytophagous mites belonging to nine genera of the two families Tetranychidae and Tenuipalpidae. The mitochondrial genetic code used in mites appeared to be the same as in insects. As is generally also the case in insects, the mite sequences were very rich in A + T (75% on average), especially at the third codon position (94%). However, important variations of base composition were observed among mite species, one of them showing as little as 69% A + T. Variations of base composition occur mostly through synonymous transitions, and do not have detectable effects on polypeptide evolution in this group.

Animals↗
PubMed1994

Intraspecific diversity of the Cassava green mite Mononychellus progresivus (Acari: Tetranychidae) using comparisons of mitochondrial and nuclear ribosomal DNA sequences and cross-breeding.

Intraspecific diversity in Cassava Green Mite Mononychellus progresivus Doreste was examined using individuals collected in Benin and the Congo and in Columbia and Brazil. Comparisons were based on mitochondrial and ribosomal DNA sequences and the results of several cross-breeding experiments. Sequence variation was examined in a total of 1139 base pairs (bp) constituting the ITS2 ribosomal DNA (805 bp) and a fragment of the Cytochrome Oxidase I (COI) gene (334 bp). Sequence divergence is low, ranging from 0% to 2.1% for COI and from 0% to 0.4% for ITS2. Inter-strain comparisons have shown that the two African populations appear to be identical. They were similar to the Colombian population while the Brazilian population was clearly different. The data support the hypothesis of a single introduction of the species in the two African populations. Crossing experiments have shown partial hybrid sterility, suggesting a genetic incompatibility consistent with differences detected by sequence data. The results show the usefulness of molecular markers as a tool for determining taxonomic status and dispersion paths in spider mites.

Animals↗
PubMed1994

Mitochondrial DNA from a spider mite: isolation, restriction map and partial sequence of the cytochrome oxidase subunit I gene.

Mitochondrial (mt) DNA of the phytophagous mite Tetranychus urticae was purified and a restriction map was constructed. The 12.5 kb long genome is the shortest animal mtDNA known. A 564 bp clone comprising part of the gene for cytochrome oxidase subunit I was sequenced. As has been found in insects, the mitochondrial sequences of mites are extremely A+T rich (75% on average, 96.5% at the third codon position).

Animals↗
PubMed1992

Molecular approach in spider mites (Acari: Tetranychidae): preliminary data on ribosomal DNA sequences.

DNA sequence data were used to examine phylogenetic relationships between six species of economically important Tetranychidae mites: Eotetranychus carpini (Oudemans), E. pruni (Reck), Tetranychus pacificus McGregor, T. mcdanieli McGregor, T. turkestani Ugarov & Nikolski and T. urticae Koch. With primers directed toward conserved elements flanking the target region, the Polymerase Chain Reaction was used to amplify the ITS2 spacer of the ribosomal DNA molecule. The nucleotide sequence of a 300-bp fragment of the ITS2 was determined by direct sequencing and nucleotide divergence used for intra-generic comparison in mites. The resulting phylogenetic tree expressing interspecific relationships in genus Tetranychus agrees with morphological data. The study demonstrates the usefulness of the approach in the assessment of the systematics and evolution of the group.

Acari↗
PubMed1990

Detection by denaturing gradient gel electrophoresis of a new polymorphism in the apolipoprotein B gene.

The apolipoprotein B gene is subject to mutations that may be important in coronary heart diseases. We have used polymerase chain reaction and denaturing gradient gel electrophoresis to characterize a single nucleotide substitution in the apolipoprotein B gene. This mutation affects amino acid 4311 of the protein and converts asparagine to serine. It was found in 24% of the 81 unrelated individuals analyzed. Moreover, another mutation was detected by sequencing in a single individual.

Apolipoproteins B↗
PubMed1989

Combined ascending aorta rupture and left main bronchus disruption from blunt chest trauma.

After blunt chest trauma, early diagnosis of associated bronchial, vascular, and esophageal injuries must be attempted, as those lesions may be produced by the same mechanism. We report a case of successful management of associated bronchial transection and injury of the ascending aorta. Aortic repair required cardiopulmonary bypass and the use of prosthetic materials, although gross contamination of the mediastinum from the bronchial disruption is a theoretical contraindication to such a procedure. A separate approach to the vascular and airway injuries allowed successful management of both lesions.

Adult↗
PubMed1988

Tracheal sleeve pneumonectomy for bronchogenic carcinoma: report of 55 cases.

From 1966 to 1986, a total of 55 patients underwent a tracheal sleeve pneumonectomy (53 right and 2 left) for bronchogenic carcinoma. Preoperative radiotherapy was given in only 5 patients. The overall operative death rate was 10.9%, but no patient has died since 1975 (32 survivors). Seven patients had a postoperative empyema (12.7%); 4 of these patients had a bronchopleural fistula. Twenty-five patients had postoperative radiotherapy, 5 of whom also had chemotherapy. The actuarial survival rate, after exclusion of the 6 operative deaths, was 38% at 3 years and 23% at 5 years. Survival was correlated to regional lymph node involvement. The actuarial survival rate among patients with tumoral spread to bronchial lymph nodes was 43% at 3 years. Among the 13 patients with only subcarinal involvement, the actuarial survival rate was 34% at 3 years. None of the 8 patients with paratracheal lymph node involvement survived more than 30 months. These results indicate that tracheal sleeve pneumonectomy for bronchogenic carcinoma with extension to the carina is now fully justified considering the low operative mortality and the good results observed when lateral tracheal lymph nodes were not involved.

Adult↗
PubMed1988

[Thymomas and associated diseases. Apropos of a series of 255 surgically treated thymomas].

The authors report on a series of 255 thymomas and the associated diseases most often auto-immune, myasthenia is the disease most frequently encountered (61% of cases). Next, but with a much reduced frequency of around 2%, come other diseases such as hypogammaglobulinaemia, erythroblastopenic anaemia, and disseminated lupus erythematosis. The authors analyse the effect of ablating the thymoma on the associated disease; those with myasthenia are the principal beneficiaries of thymic ablation, 83% in this series experiencing a good response. Besides myasthenia only erythroblastopenic anaemia obtained some benefit from thymic ablation; in all the other cases surgery to the thymic tumour had no benefit on the associated disease. In the light of their own experience the authors made a review of the literature of the different diseases associated with thymomas and made the point of the efficacy of thymectomy in the different diseases.

Agammaglobulinemia↗
PubMed1987

Congenital tracheobiliary fistula.

Congenital tracheobiliary fistulas are uncommon and almost always are diagnosed in the first weeks or months of life. Untreated congenital tracheobiliary fistulas cause intractable pneumonia and are revealed by a persistent cough. Medical therapy is not effective, and surgical repair is needed. A 22-year-old woman was treated successfully by resection of a fistula communicating between the tracheobronchial tree and the liver.

Adult↗
PubMed1987

Replacement of the superior vena cava with polytetrafluoroethylene grafts combined with resection of mediastinal-pulmonary malignant tumors. Report of thirteen cases.

From 1979 to 1986, we replaced the superior vena cava with polytetrafluoroethylene grafts in 13 patients to enable resection of malignant mediastinal or pulmonary tumors. Five prostheses could be interposed between a tumor-free proximal superior vena cava and right atrium while eight required separate innominate anastomoses (Y grafts constructed intraoperatively). There were no deaths. Phlebograms obtained 15 to 30 days after the operation demonstrated patency in 12 of 13 patients. Long-term (average 24 months) patency was evident in eight. Five patients are alive at 1, 3, 40, 49, and 60 months, a cumulative survival rate of 27% at 3 years.

Adult↗