Search PubMed⌕ Search

Biomedical subjects

M Cardoso

Publications and source records attributed to M Cardoso.

At least 37 records · Page 2Linked to original sources
PubMed1992

Chloramphenicol resistance plasmids in Staphylococcus aureus isolated from bovine subclinical mastitis.

Chloramphenicol resistance (CmR) could be detected in 11 of 217 Staphylococcus aureus isolates from bovine subclinical mastitis. All isolates were assigned to biotypes A or C. The CmR-determinants were found to be located exclusively on small plasmids of approximately 4.6 kb as revealed by protoplast transformation. The 11 CmR-plasmids could be differentiated on the basis of restriction endonuclease analyses. The restriction maps of these CmR-plasmids identified two separate groups. One group demonstrated homology to the plasmid pC 221, the other to the plasmid pC 223. Both prototype plasmids, pC 221 and pC 223, had been isolated from S. aureus of human origin.

Animals↗
PubMed1992

Characterization of the chloramphenicol acetyltransferase variants encoded by the plasmids pSCS6 and pSCS7 from Staphylococcus aureus.

The two 4.6 kb chloramphenicol resistance (CmR) plasmids pSCS6 and pSCS7, previously identified in Staphylococcus aureus from subclinical bovine mastitis, both encoded an inducible chloramphenicol acetyltransferase (CAT, EC 2.3.1.28). The pSCS6- and pSCS7-encoded CAT variants were purified by ammonium sulphate precipitation, ion-exchange chromatography and fast protein liquid chromatography (FPLC). Both native enzymes showed Mr values of 70,000 on FPLC and were composed of three identical subunits, each of Mr approximately 23,000. The CAT variants from pSCS6 and pSCS7 differed in their net charges and in their isoelectric points. The isoelectric point of the CAT from pSCS6 was pH 5.7 and that of the CAT from pSCS7 pH 5.2. Both CAT variants exhibited highest enzyme activities at pH 8.0. The Km values for chloramphenicol and acetyl-CoA of the CAT from pSCS6 were 2.5 microM and 58.8 microM, respectively, while those of the CAT from pSCS7 were 2.7 microM and 55.5 microM. Both CAT variants were relatively thermostable. The CAT from pSCS6 was less sensitive to mercuric ions than the CAT from pSCS7.

Amino Acid Sequence↗
PubMed1992

Nucleotide sequence and structural relationships of a chloramphenicol acetyltransferase encoded by the plasmid pSCS6 from Staphylococcus aureus.

The 4.6 kb chloramphenicol resistance (Cm) plasmid, pSCS6, isolated from a naturally occurring Staphylococcus aureus biotype C encoded an inducible chloramphenicol acetyltransferase (CAT). The respective cat gene and its regulatory region were cloned. Sequence analyses revealed two open reading frames: one for a 9-amino acid leader peptide and the other for the 215-amino acid CAT monomer. Comparisons of the predicted CAT amino acid sequences revealed a high degree of similarity between CAT from pSCS6 and the CAT variants encoded by Cm plasmids of the pC221 family. These close structural relationships suggested an intraspecific exchange of Cm-determinants between Staph. aureus of human and bovine biotype.

Amino Acid Sequence↗
PubMed1992

Nucleotide sequence and phylogeny of the tet(L) tetracycline resistance determinant encoded by plasmid pSTE1 from Staphylococcus hyicus.

The nucleotide sequence of the tetracycline resistance (tet) gene and its regulatory region, encoded by the plasmid pSTE1 from Staphylococcus hyicus, was determined. The tet gene was inducible by tetracycline and encoded a hydrophobic protein of 458 amino acids. Comparisons between the predicted amino acid sequences of the pSTE1-encoded Tet from S. hyicus and the previously sequenced Tet K variants from Staphylococcus aureus, Tet L variants from Bacillus cereus, Bacillus stearothermophilus, and Bacillus subtilis, Tet M variants from Streptococcus faecalis and Staphylococcus aureus as well as Tet O from Streptococcus mutans were performed. An alignment of Tet amino acid sequences revealed the presence of 30 conserved amino acids among these Tet variants. On the basis of the alignment, a phylogenetic tree was constructed. It demonstrated large evolutionary distances between the Tet M and Tet O variants on one hand and the Tet K and Tet L variants on the other hand. The pSTE1-encoded Tet proved to be closely related to the Tet L proteins originally found on small Bacillus plasmids. The observed extensive similarities in the nucleotide sequences of the tet genes and in the deduced Tet amino acid sequences allowed the assignment of the pSTE1-encoded Tet to the Tet proteins of class L.

Amino Acid Sequence↗
PubMed1992

Cryopreserved autologous platelet transfusions in alloimmunized patients with acute leukemia.

Autologous platelets of 5 alloimmunized patients with acute leukemia in remission were cryopreserved with 5% dimethylsulfoxide in liquid nitrogen and retransfused in the following therapy-induced thrombocytopenic phase. The mean platelet recovery after freezing, thawing and washing was 85 +/- 6%. The mean corrected 1-hour increment in platelet counts was 11 (4-27) x 10(9)/l, i.e. 61% in comparison with fresh platelet transfusions in other patients. In vivo function of frozen platelets was documented by improvement of the posttransfusion bleeding time. Cryopreserved autologous platelets function hemostatically and can be used even for completely refractory patients and thus permit curative antileukemic therapy.

Adult↗
PubMed1992

[The application of the problem-solving method in a situation of surgical intervention; a case report].

This study used the problems solving method for directing nursing assistance to the hospitalized surgical patient. We present the elaborate instrument founded in the Bailey e Claus model which is analyzed and exemplified. The authors consider the available resources concluding that the proposed is possible to be established. They realize how necessary is in nursing all the taking decision process to reach the proposed objectives, toward the resolution of the patient problems.

Brazil↗
PubMed1991

Cloning and sequence analysis of a plasmid-encoded chloramphenicol acetyltransferase gene from Staphylococcus intermedius.

The chloramphenicol acetyltransferase gene (cat) of a 3.9 kb chloramphenicol resistance (CmR) plasmid from Staphylococcus intermedius, designated pSCS1, was cloned into an Escherichia coli plasmid vector. Sequence analysis revealed a high degree of base similarity with the cat gene of the S. aureus CmR plasmid pC221 but there were several differences in the regulatory region. A lesser degree of similarity was observed between the cat gene of the S. intermedius plasmid and the cat gene of the S. aureus plasmid pC194.

Amino Acid Sequence↗
PubMed1991

Molecular cloning, purification, and properties of a plasmid-encoded chloramphenicol acetyltransferase from Staphylococcus haemolyticus.

A small chloramphenicol resistance (Cmr) plasmid of approximately 3.75 kb, designated pSCS5, was isolated from Staphylococcus haemolyticus. This plasmid encoded an inducible chloramphenicol acetyltransferase (CAT; EC 2.3.1.28). The cat gene of pSCS5 was cloned into the Escherichia coli plasmid vector pBluescript SKII+. It differed in its nucleotide sequence and deduced amino acid sequence from the cat genes described previously in staphylococci and other gram-positive bacteria. The CAT enzyme was purified from cell-free lysates by ammonium sulfate precipitation, ion-exchange chromatography, and fast protein liquid chromatography. The native enzyme had an Mr of 70,000 and was composed of three identical subunits, each with an Mr of approximately 23,000. Its isoelectric point was at pH 6.15. CAT from pSCS5 exhibited Km values of 2.81 and 51.8 microM for chloramphenicol and acetyl coenzyme A, respectively. The optimum pH for activity was 7.8. CAT encoded by pSCS5 proved to be relatively heat stable, but sensitive to mercury ions. The observed differences in the nucleotide sequence and the biochemical characteristics of the enzyme allowed the identification of the pSCS5-encoded CAT from S. haemolyticus as a CAT variant different from those described previously in gram-positive bacteria.

Amino Acid Sequence↗
PubMed1991

Nucleotide sequence and phylogeny of a chloramphenicol acetyltransferase encoded by the plasmid pSCS7 from Staphylococcus aureus.

The nucleotide sequence of the chloramphenicol acetyltransferase gene (cat) and its regulatory region, encoded by the plasmid pSCS7 from Staphylococcus aureus, was determined. The structural cat gene encoded a protein of 209 amino acids, which represented one monomer of the enzyme chloramphenicol acetyltransferase (CAT). Comparisons between the amino acid sequences of the pSCS7-encoded CAT from S. aureus and the previously sequenced CAT variants from S. aureus, Staphylococcus intermedius, Staphylococcus haemolyticus, Bacillus pumilis, Clostridium difficile, Clostridium perfringens, Escherichia coli, Shigella flexneri, and Proteus mirabilis were performed. An alignment of CAT amino acid sequences demonstrated the presence of 34 conserved amino acids among all CAT variants. These conserved residues were considered for their possible roles in the structure and function of CAT. On the basis of the alignment, a phylogenetic tree was constructed. It demonstrated relatively large evolutionary distances between the CAT variants of enteric bacteria, Clostridium, Bacillus, and Staphylococcus species.

Amino Acid Sequence↗
PubMed1990

Common antibiotic resistance plasmids in Staphylococcus aureus and Staphylococcus epidermidis from human and canine infections.

The plasmids of a multiresistant "canine" Staphylococcus epidermidis-culture were investigated. Two small plasmids, the 4.55 kB chloramphenicol resistance (CmR-) plasmid pSC4 and the 4.45 kB tetracycline resistance (TetR-) plasmid pST 3 could be isolated. Detailed restriction maps of pSC 4 and pST 3 were constructed by double restriction endonuclease digests. The restriction maps revealed extensive structural homologies between pSC 4 from "canine" S. epidermidis and the CmR-plasmid pC 221 from "human" S. aureus as well as between pST 3 from "canine" S. epidermidis and the TetR-plasmid pT 181 from "human" S. aureus. These data suggested that an exchange of small plasmids between S. epidermidis and S. aureus might be possible.

Animals↗
PubMed1990

Detection of a novel chloramphenicol resistance plasmid from "equine" Staphylococcus sciuri.

A small chloramphenicol resistance (Cm) plasmid of 4.65 kB could be detected in an "equine" Staphylococcus sciuri-culture. This plasmid, designated as pSC3, was identified by interspecific protoplast transformation. On the basis of restriction endonuclease analyses a detailed restriction map of pSC3 could be constructed. This allowed structural comparisons of pSC3 with Cm-plasmids of other staphylococcal species from infections of humans and animals and identification of pSC3 as a member of the pC 221-family of staphylococcal Cm-plasmids. The pSC3-plasmid encoded an inducible chloramphenicol acetyltransferase as confirmed by enzymatic assays. This enzyme could be demonstrated in cell-free lysates of Cm-induced pSC3-transformants.

Animals↗
PubMed1990

[Plasmid-encoded antibiotic resistance in Staphylococcus hyicus].

A total of 33 Staphylococcus hyicus-cultures from piglets with exudative epidermatitis were analyzed for the presence of antibiotic resistance plasmids. Four small plasmids encoding resistances to chloramphenicol, macrolide-lincosamide-antibiotics, streptomycin or tetracyclines could be identified in plasmid-curing and plasmid-transformation experiments. For further characterization these plasmids were digested with restriction endonucleases. This led to the construction of a specific restriction map for each of the 4 plasmids. On the basis of their restriction maps, these 4 antibiotic resistance plasmids from "porcine" S. hyicus-cultures were compared with the respective resistance plasmids of other staphylococcal species from infections of humans and animals.

Animals↗
PubMed1989

Plasmid-mediated chloramphenicol resistance in Staphylococcus hyicus.

A small plasmid of 3.95 kb, encoding resistance to chloramphenicol (Cm) was detected in three of 33 Staphylococcus hyicus strains. The plasmid in each of the three strains was indistinguishable by Southern-blot hybridization and restriction enzyme analysis. It was shown by curing and by transformation to specify resistance to Cm. A preliminary restriction map of the plasmid, designated pSC2, is presented. Chloramphenicol acetyltransferase was demonstrated by enzyme assay and by SDS-PAGE of cell-free lysates of pSC2 transformants.

Animals↗
PubMed1989

Metabolic effects of acetate on the heart.

The effects of various substrates (15 mM glucose, 5 mM glucose, 20 mM acetate, or a combination of these substrates) on the coronary blood flow and on the energetic status of myocytes were studied in isolated perfused rat hearts. We demonstrate that low level glucose (5 mM) or high concentration of acetate (20 mM) leads to a simultaneous fall in tissue ATP, rise in tissue adenosine, and significant increment in coronary blood flow. The latter effect is especially marked with 20 mM acetate. Dipyridamole (10(-6) M) does not enhance the vasodilatation induced by acetate. The provision of 15 mM glucose together with 20 mM acetate fully prevents these changes, indicating that the vasodilatation induced by acetate is probably mediated by metabolic changes. The evidence supports the concept that a redistribution of blood flow together with a fall in tissue ATP may explain some of the adverse effects of acetate dialysis in man, and suggests that the provision of glucose may alleviate these changes.

Acetates↗
PubMed1988

Hypoxemia during hemodialysis: a critical review of the facts.

The literature describing the fall in PaO2 during dialysis is intensively and critically reviewed. This phenomenon is related to both the type of membrane used (cellulosic v noncellulosic membrane), and to the composition of the dialysate (acetate v bicarbonate). It appears that a ventilation/perfusion mismatch due to pulmonary leukostasis can, in part, explain hypoxemia in patients dialyzed with cellulosic membranes. This phenomenon is especially apparent in patients with preexisting pulmonary abnormalities. However, hypoventilation remains the major cause of hypoxemia. This hypoventilation is mainly due to CO2 consumption during acetate metabolism (acetate dialysis), or alkalinization of the blood (bicarbonate dialysis). The metabolic consequences of acetate metabolism, and of bicarbonate and CO2 losses through the dialyzer are critically analyzed. The cause for the increment in oxygen consumption during acetate dialysis is examined. Finally, the respective role of these combined factors are described and used to explain the changes in VCO2, VO2, respiratory quotient (RQ), and PaO2 reported in the literature during dialysis against acetate and/or bicarbonate.

Carbon Dioxide↗
PubMed1988

NMR monitoring of the energy status of skeletal muscle during hemodialysis using acetate.

The concentration of phosphate-containing metabolites in the resting gastrocnemius muscle of three patients in chronic renal insufficiency was monitored by NMR spectroscopy before and during their regular hemodialysis using a conventional acetate bath. During dialysis, the muscle ATP concentration did not change, and no significant pyrophosphate accumulation was seen. The intracellular and extracellular inorganic phosphate concentration fell as expected. It is concluded that the rapid metabolism of acetate induced by dialysis does not affect the concentration of high energy phosphate-metabolites in the resting muscle of acetate-tolerant patients.

Acetates↗
PubMed1987

Acetate metabolism during hemodialysis: metabolic considerations.

Acetate is used during regular hemodialysis to replace the bicarbonate lost during dialysis. The temporal changes of plasma bicarbonate and acetate concentrations and the critical role of acetate metabolism for the maintenance of plasma bicarbonate are described. We point out that the maximal rate of acetate oxidation in man is usually reached during dialysis, and we identify physiologic and pathologic factors that may modify this Vmax. A syndrome of 'intolerance to acetate' has been described. This syndrome is analyzed in the light of the metabolic consequences of a rapid flux of acetate oxidation in liver and muscle cells. More specifically, the effects of rapid acetate metabolism on tissue ATP, CoA, adenosine and other ATP degradation products are presented. The possible impact of dialysis-induced depletion of carnitine on optimal acetate metabolism is discussed. The potential clinical consequences produced by these changes are presented in relation to the symptoms sometimes observed during dialysis against acetate: vasodilation, hypotension and angina pectoris. The hypoxemia induced by acetate is also briefly reviewed. Different directions are proposed for future research.

Acetates↗