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Biomedical subjects

M Sebald

Publications and source records attributed to M Sebald.

At least 19 recordsLinked to original sources
PubMed2003

Use of high-frequency jet ventilation in neonates with hypoxemia refractory to high-frequency oscillatory ventilation.

OBJECTIVE: To describe the response to high-frequency jet ventilation in infants with hypoxemic respiratory failure unresponsive to high-frequency oscillatory ventilation. METHODS: This was a retrospective analysis of chart records on demographics, ventilator settings, blood gas analysis and calculated oxygenation index prior to and during the first 7 days of high-frequency jet ventilation in ten consecutive infants. RESULTS: Before the initiation of high-frequency jet ventilation, the ventilatory mean airway pressure (MAP; cmH2O), fraction of inspired oxygen (FiO2) and oxygenation index on high-frequency oscillatory ventilation were 14.3 +/- 1.3, 0.97 +/- 0.02 and 29 +/- 5, respectively. Three hours after the initiation of high-frequency jet ventilation, the oxygenation index improved to 18 +/- 4 (p < 0.001) and the improvement was sustained during the study period. By 6 h of high-frequency jet ventilation, the FiO2 decreased to 0.62 +/- 0.09 (p < 0.01) and, by 1-3 h of ventilation, the MAP decreased to 10.9 +/- 1.3 (p < 0.01). The improvement in FiO2 persisted for 7 days while, although the MAP remained lower throughout the study, the improvement in MAP failed to reach statistical significance after 72 h. No significant changes in pH, pCO2, or pO2 before or during high-frequency jet ventilation were noted. CONCLUSION: High-frequency jet ventilation improves hypoxemic respiratory failure unresponsive to high-frequency oscillatory ventilation in infants. These findings suggest that not all high-frequency ventilatory devices yield the same clinical results.

Airway Resistance↗
PubMed1996

Meningitis due to enterotoxigenic Bacteroides fragilis.

An enterotoxigenic strain of Bacteroides fragilis was the sole organism isolated from the cerebrospinal fluid of a two-and-a-half-month neonate who had a medullary-colonic fistula as part of a complex congenital malformation, but no brain abscess. A rapid latex particle agglutination test for detection of bacterial antigen was positive for Haemophilus influenzae type b, suggesting that Bacteroides fragilis and Haemophilus influenzae type b might share some capsular antigens. In order to determine the role of the enterotoxin with respect to virulence of the strain, antibodies to a 20 kDa protein were sought in the patient's serum, but Western blot of the culture supernatant revealed only antibodies to a 45 kDa bacterial protein. The patient was successfully treated with metronidazole and imipenem.

Antibodies, Bacterial↗
PubMed1995

Pasteur, oxygen and the anaerobes revisited.

As a biochemist, Louis Pasteur focused on fermentation, demonstrating that it was a vital process. In 1860, he discovered anaerobic life and the strict anaerobes, particularly those responsible for butyric fermentation. Then, in spite of his lack of medical background, Pasteur turned to investigating the role of bacteria in human and animal diseases. In 1877, Pasteur and Joubert described for the first time a pathogenic anaerobe, the 'septic vibrio' (now Clostridium septicum). Not only was the bacterium cultivated, but the disease symptoms described and the disease experimentally reproduced. Pasteur also described what are now known as mixed anaerobic infections. A historical review of Pasteur's work is made in the light of our present knowledge of this field.

Journal Article↗
PubMed1995

Plasmids pIP419 and pIP421 from Bacteroides: 5-nitroimidazole resistance genes and their upstream insertion sequence elements.

The genetic organization of two different 5-nitroimidazole (5-Ni) resistance genes was investigated: nimC and nimD from Bacteroides plasmids pIP419 and pIP421, respectively. The nimC gene (492 bp) and the nimD gene (495 bp) directed the synthesis of polypeptides with deduced molecular masses of 18.37 kDa and 18.48 kDa, respectively. The predicted proteins showed 67-83% identity and 78-91% similarity with the products of two other nimA and nimB genes previously described and could be derived from a common ancestral gene. An insertion sequence element (IS1170) was identified upstream of the nimC gene. IS1170 is 1604 bp in length and is flanked by imperfect inverted repeats (15 bp). IS1170 is similar to the Bacteroides insertion sequence element IS942 with an identity of 70% at the nucleotide level. The single copy of IS1170 present on plasmid pIP419 is integrated 24 bp upstream of the initiation codon of nimC. Similar genetic organization was found on plasmid pIP421. One copy of another insertion sequence (IS1169) was found 4 bp upstream of the first ATG codon of the nimD gene. This element (1325 bp) shows a strong homology at the nucleotide level (70% identity) with IS1186 and IS1168 found to be associated with the Bacteroides carbapenem resistance gene cfiA, and the 5-Nirgenes nimA and nimB, respectively. There is strong evidence that, as in the case of the cfiA gene, the transcription of the four nim genes so far studied is directed by outward-oriented promoters, carried on the right ends of the different insertion sequence elements.

Amino Acid Sequence↗
PubMed1994

Genetic basis for antibiotic resistance in anaerobes.

This review focuses on genetic and molecular data regarding antibiotic resistance in anaerobes, particularly Clostridium perfringens, Clostridium difficile, Bacteroides species, and Prevotella species. The determinants of resistance are frequently transferable through a conjugation-like process; plasmid self-transfer, plasmid mobilization, or (in Bacteroides species) chromosomal conjugative elements can be involved. The determinants can be localized on transposons. At the genetic level, resistance determinants can be highly specific for one or several anaerobes or may exhibit homology with genes from aerobes. The latter observation suggests that anaerobes are able to exchange genetic material from a "gene pool" shared with aerobic organisms.

Bacteria, Anaerobic↗
PubMed1994

Nucleotide sequence analysis of two 5-nitroimidazole resistance determinants from Bacteroides strains and of a new insertion sequence upstream of the two genes.

DNA sequence analysis of regions from plasmid pIP417 and chromosome BF8 which encode 5-nitroimidazole resistance in Bacteroides strains allowed the identification of two open reading frames corresponding to new genes, nimA (528 bp) and nimB (492 bp). Either gene may confer 5-nitroimidazole resistance to susceptible strains of Bacteroides. The encoded polypeptides have deduced molecular masses of 20.1 and 18.6 kDa, respectively, and share about 73% identity and 85% similarity. A new insertion sequence (IS) element named IS1168 lies 14 bases upstream of the nimA gene. The complete sequence of IS1168 was determined. A similar IS exists 12 bp upstream of the nimB gene. About 60% of the BF8 IS element was also sequenced and shown to be almost identical to IS1168.

Bacteroides↗
PubMed1994

Zinc, a structural component of adenylate kinases from gram-positive bacteria.

The recent finding that Bacillus stearothermophilus adenylate kinase contains a zinc atom coordinated to four cysteines prompted us to investigate the metal-binding properties of the enzyme from various bacteria. We conclude that zinc was present only in adenylate kinase from gram-positive species and that this property is correlated with the presence of three or four Cys residues in the sequence Cys-X2-Cys-X16-Cys-X2-Cys/Asp, in which X stands for different amino acid residues.

Adenylate Kinase↗
PubMed1994

Isolation of enterotoxigenic Bacteroides fragilis strains in Poland.

Fecal samples of 120 children (2 weeks to 3.5 year old) hospitalized in a pediatrical ward were investigated. In 56 of them diarrhea was observed. Out of 45 anaerobic gram-negative isolated rods, two Bacteroides fragilis strains were enterotoxigenic. Production of enterotoxin was established on the Human Colonic Epithelial Cell Line HT29/C1.

Bacteroides Infections↗
PubMed1993

Genetics of resistance of Bacteroides species to 5-nitroimidazole.

Thirty-three clinical isolates of Bacteroides strains with a moderate-to-high level of resistance to 5-nitroimidazole were compared with three strains previously studied by Southern blotting of their DNA. Whether plasmid-borne or chromosomally determined, all genetic determinants that are resistant to 5-nitroimidazole belong to two hybridization groups.

Bacteroides↗
PubMed1993

Botulinum antibodies in dystonic patients treated with type A botulinum toxin: frequency and significance.

We measured serum antibodies to botulinum toxin (ABT) in 96 patients with focal dystonia who had been treated with type A botulinum toxin. The frequency of detectable ABT was 3% (three patients). Patients with ABT had received more than 50 ng of botulinum toxin, and the shortest time between two injections was significantly less than in patients without ABT. The clinical evolution of the three patients was heterogeneous: one had decreased effectiveness with repeated injections, another had persistent improvement, and the third never responded to toxin injections.

Adolescent↗
PubMed1992

Cloning of a Bacteroides fragilis chromosomal determinant coding for 5-nitroimidazole resistance.

Strain BF8 is a plasmid-free Bacteroides fragilis, resistant to 5-nitroimidazole (5-Ni) antibiotics (metronidazole, ornidazole and tinidazole). The resistance was transferable by conjugation into Bacteroides fragilis BF638R. The total DNA of a Nir transconjugant was used for the construction of a Sau3A genomic library in a B. fragilis cloning vector pFK707 delta H1 (4.2 kb). By electrotransformation of strain BF638R, a recombinant plasmid containing an insert of 5.4 kb was obtained which conferred to the host strain the resistance to 5-Ni. The physical map of the insert was established. After deletion analysis of the insert, the Nir determinant was localized on a HpaII-HincII fragment of 1.6 kb in size. This Nir determinant has been compared by Southern-blot analysis with other Bacteroides Nir determinants of plasmid origin.

Bacteroides fragilis↗
PubMed1992

Genetic and molecular analysis of pIP417 and pIP419: Bacteroides plasmids encoding 5-nitroimidazole resistance.

This report describes a genetic and molecular analysis of two transferable Bacteroides plasmids, pIP417 and pIP419, which carry genetic determinants conferring low-level resistance to 5-nitroimidazoles. The restriction endonuclease cleavage sites for each plasmid were localized. The NiR genetic determinants of pIP417 and pIP419 plasmids have been cloned into the Bacteroides cloning vector pBI191 (C.J. Smith, J. Bacteriol. 164, 294-301, 1985) as PvuII and Sau3A fragments, respectively. Both inserts had different restriction sites and did not cross-hybridize by Southern blot analysis. Genetic data obtained by cloning into pBI191 clearly show that the PvuII-generated fragments A (Rep) and B (Mob) of pIP417 are involved in plasmid replication and transfer, respectively. Although encoding resistance to the same antibiotic, both plasmids appeared different with regard to the 5-nitroimidazole resistance and replication genetic determinants. However, they share a homology in a region involved, at least in one case, in plasmid transfer. Considering the spontaneous high level of resistance to 5-nitroimidazole in Escherichia coli, this work, based on direct gene cloning into Bacteroides, demonstrates the value of such an approach.

Bacteroides↗
PubMed1992

[An automatic gas scanning device, technical improvement for obtaining a favourable atmosphere for in vitro culture of anaerobic bacteria].

All methods for growth of anaerobic bacteria on solid media depend on the elimination of atmospheric O2 through use of a palladium catalyst (Deoxo-Catalyst), active in presence of at least 5% H2 with resultant formation of water. Anaerobic chambers and jars are the two conventional methods employed. Both are based on the elimination of air by means of a pump and its replacement with gas from a cylinder (evacuation-replacement technique). An alternative chemical technique for use in anaerobic jars consists of adding internal gas-generating sachets. The former techniques are more efficient but the trend, particularly in the clinical laboratories, is to use the simpler chemical system that has two inconveniences: a slow establishment of anaerobiosis, and a high cost. We propose a new system that does not require a vacuum pump and consists in flushing anaerobic jars with a convenient gas mixture (H2, CO2, N2: 4.5; 5; 90.5 v/v) by means of an automaton regulating both time and gas flow. Gas-liquid chromatography analysis of the gas inside the jar shows a rapid elimination of gaseous O2, whose residual concentration is low enough to permit growth of all anaerobes of clinical interest, including those which are more O2-sensitive. Comparative qualitative and quantitative data obtained with all available techniques demonstrate the advantages of the new system.

Anaerobiosis↗
PubMed1990

Bacteremias caused by Selenomonas artemidis and Selenomonas infelix.

We report two different cases of bacteremia caused by two recently described Selenomonas species, Selenomonas artemidis and Selenomonas infelix. Both species are normally found in human buccal flora. S. artemidis bacteremia appeared in a patient (number 1) who presented with an air-fluid pulmonary cavity and clinical conditions consistent with an anaerobic lung abscess. While the patient improved with antibiotic therapy, cultures of respiratory secretions yielded Mycobacterium tuberculosis. This case demonstrated a strong possibility of a coexisting lung abscess due to S. artemidis. S. infelix bacteremia appeared in a cancer patient (number 2) with heart disease during preterminal acute respiratory distress. It was more difficult in this case to assess the clinical impact of the Selenomonas organisms on the patient.

Adenocarcinoma↗