PubMed Health⌕ Search

Biomedical subjects

G Odham

Publications and source records attributed to G Odham.

At least 37 records · Page 2Linked to original sources
PubMed1983

Determination of fatty acids and carbohydrate monomers in micro-organisms by means of glass capillary gas chromatography: analysis of Mycobacterium gordonae and Mycobacterium scrofulaceum.

Trifluoroacetylated whole-cell methanolysates of four strains each of Mycobacterium gordonae and Mycobacterium scrofulaceum were analysed by gas chromatography, using a glass capillary column. The major chromatographic peaks were identified by mass spectrometry as derivatives of fatty acids and carbohydrates. In addition, two predominant peaks, present in chromatograms representing M. scrofulaceum, were identified as 2-octadecanol and 2-eicosanol. These secondary alcohols were not found in any of the strains of M. gordonae studied. The amount of tuberculostearic acid in the latter species was less than 1% of that in M. scrofulaceum.

Carbohydrates↗
PubMed1982

Diagnosis of bacteraemia by automated head-space capillary gas chromatography.

Blood cultures from 196 patients with suspected bacteraemia or septicaemia were analysed by automated head-space gas chromatography, using a 25 m fused silica capillary column, when turbidity indicated growth. Gas chromatography correctly identified 105 cultures as positive and 71 correctly as negative. No false-positive results were obtained. Of the 20 false-negative chromatographic results, Staphylococcus spp accounted for 14. Automated head-space gas chromatography is quicker, easier and more efficient than other gas chromatographic techniques for the evaluation of blood cultures.

Chromatography, Gas↗
PubMed1981

Use of selected ion monitoring for detection of tuberculostearic and C32 mycocerosic acid in mycobacteria and in five-day-old cultures of sputum specimens from patients with pulmonary tuberculosis.

Gas chromatography/mass spectrometry and selected ion monitoring (SIM), employing both electron (EI) and chemical ionization (CI), was used to detect 10-methyloctadecanoic (tuberculostearic) and 2, 4, 8, 8-tetramethyloctacosanoic (C32 mycocerosic) acids in bacteria of 14 species of Mycobacterium and 3 species of Nocardia. Tuberculostearic acid was found in all species studied, while C32 mycocerosic acid was demonstrated only in M. africanum, M bovis, M. bovis strain BCG, M. kansasii and M. tuberculosis. The relative amounts of these acids in the organisms of these five species varied, thereby constituting a presumptive diagnostic technique. The lowest detectable amount of C32 mycocerosic acid was approximately 5 pg when using EI-SIM, monitoring at m/zz 88 and m/z 101. When using CI, employing isobutane as reactant gas, and focusing at m/z 495, 2 pg could be detected, and when ammonia was the reactant gas, the corresponding figure was 1 pg, monitoring at m/z 512. Tuberculostearic acid was demonstrated in 5-day incubated sputum specimens from 6 patients with pulmonary tuberculosis, including 5 patients infected with M tuberculosis and 1 patient infected with M. avium. C32 mycocerosic acid was detected in 4 of the 5 patients with M. tuberculosis infection. None of the acids was found in a further 8 patients who had viral or bacterial (non-mycobacterial) pneumonia. Tuberculostearic acid could be demonstrated in 10 of another 12 sputum specimens from patients with tuberculosis, when the samples were analyzed directly, viz prior to culturing. The possibility of using SIM for the rapid diagnosis of pulmonary tuberculosis is thus worth consideration.

Actinomycetales↗
PubMed1981

Head-space gas chromatography as a tool in the identification of anaerobic bacteria and diagnosis of anaerobic infections.

The identification of anaerobic bacteria to the species level can be a laborious and time consuming procedure. Gas chromatography offers a diagnostic aid, and the advantages of the recently introduced head-space gas chromatography technique are: it is rapid, accurate and easy to perform; it provides more information of differential diagnostic value; and the identification process can be automated by connecting the head-space gas chromatograph to an automatic injection unit and a computer which interprets the chromatograms. The head-space technique may be used for direct analyses of clinical specimens for rapid diagnoses of anaerobic infections.

Anaerobiosis↗
PubMed1979

Demonstration of tuberculostearic acid in sputum from patients with pulmonary tuberculosis by selected ion monitoring.

Selected ion monitoring was used to detect tuberculostearic acid (10-methyloctadecanoic acid) in sputum from patients with pulmonary tuberculosis. The specimens were autoclaved, lyophilized, extracted, and methanolysed before being subjected to thin-layer chromatography and injected into the gas chromatograph/mass spectrometer. Tuberculostearic acid could be detected in five of six tuberculous sputum specimens containing acid-fast rods detectable by light microscopy of Ziehl-Neelsen stained smears. After the sputum specimens had been cultured for five days on Löwenstein-Jensen medium, when still no colonies could be observed visually, the presence of tuberculostearic acid was demonstrated in all six cases of tuberculosis. In corresponding analyses of sputum from eight patients with non-tuberculous pneumonia, tuberculostearic acid was not found. This fatty acid, the presence of which was also demonstrated in cultures of various mycobacterial and nocardial species, is characteristic of organisms of the order Actinomycetales. The demonstration of tuberculostearic acid in sputum specimens may constitute a rapid and sensitive way of diagnosing pulmonary tuberculosis.

Chromatography, Gas↗
PubMed1978

Effect of inorganic ions and surface active organic compounds on the adherence of oral streptococci.

A reduction in the adherence of oral streptococci was observed after topical application of aluminum ions to standardized dentin test pieces whereas pyrophosphate and tripolyphosphate seemed to inhibit the adherence after incorporation in the incubation solution. A pronounced effect was recorded after topical application of surfactants with the positively charged primary amino group as end group. Hydrofluorides of several such aliphatic amines effectively reduced the number of colony-forming units washed off from the test pieces. Also the free base of hexadecylamine showed a similar effect. Inhibition of adherence was also obtained with long chain esters of lysine, with an optimum at 16 carbon atoms in the alcohol group. These compounds have the advantage of being built up from molecules known to the body.

Adhesiveness↗
PubMed1978

Analysis of amines and other bacterial products by head-space gas chromatography.

A gas chromatographic (GC) head-space technique is presented, which is suitable for the analysis of volatile products in bacterial broth cultures. This is exemplified by studies on Clostridium septicum, Klebsiella pneumoniae and Proteus mirabilis. The media were acidified or made alkaline and after heating, samples of the gas phase above the media were directly injected into the gas chromatograph. A gas chromatograph equipped with dual columns and flame ionization detectors was used, employing Porapak Q and Chromosorb 103 as stationary phases. Analysis of acidified media, using Porapak Q, gave chromatograms representing acidic and neutral volatile products, while when analysing samples made alkaline, using Chromosorb 103, alkaline and neutral compounds could be detected. Interest was particularly concentrated on the analysis of bacterial amines. P. mirabilis was found to produce isobutylamine and isopentylamine, which were identified by mass spectrometry and GC retention times C. septicum produced ethylamine. The GC head-space technique described constitutes a means for rapid identification of microorganisms. It is adaptable for use on a routine basis in the clinical microbiological laboratory.

Acids↗
PubMed1978

Detection of alcohols and volatile fatty acids by head-space gas chromatography in identification of anaerobic bacteria.

A head-space gas chromatographic technique for the analysis of volatile bacterial metabolites is described. Bacteroides fragilis, Clostridium perfringens, and Propionibacterium acnes, cultured in a glucose-containing peptone yeast extract medium, were studied. The head-space technique was compared with the injection of the complete liquid culture medium, and solvent extracts thereof, into the gas chromatograph. Volatile fatty acids could be detected by all three methods, whereas alcohols produced by C. perfringens and P. acnes were detectable only in the head-space chromatograms. Both FFAP and Porapak Q were used as gas chromatography stationary phase. Porapak Q was found more suitable than FFAP for the separation of alcohols. The head-space technique requires a minimum of preparation before the analysis and is well suited to automation.

Alcohols↗
PubMed1977

Intake system using glass ampoules for gas chromatographic analysis of volatile compounds of biological origin.

A gas chromatographic intake system using 1 ml glass ampoules is described. Examples of analyses of gases and volatile organic compounds produced by soil and soil organisms incubated in the ampoules are given. The gas chromatographic system was used to analyze permanent gases produced by germinating Fusarium conidia and by an agricultural soil as well as to study the respiration of Panagrellus nematodes. A comparison of the gas chromatograms of volatile organic compounds present in a beech forest soil and an agricultural soil indicates that the chromatograms represent "finger prints" of the two soils. Results obtained with the intake system described are compared to those obtained using a conventional head space technique.

Chromatography, Gas↗
PubMed1975

Antimicrobial effect of simple lipids and the effect of pH and positive ions.

Various branched fatty acids, particularly those of iso-configuration, have been shown to possess fungistatic and bacteriostatic properties. On the basis of their swelling effect on hyphae of Fusarium roseum it was suggested that this is due to an increase in the permeability of the plasma membrane. The solubilization of fatty acids in membranes should be expected to be influenced by the degree of dissociation and the presence of counter ions. Therefore, the effects of pH and K(+), Na(+), and Ca(2+) ions were studied. It is demonstrated that the presence of the univalent ions, Na(+) and K(+), markedly enhances the fungistatic effect of iso-tetradecanoic acid, whereas the opposite effect is noted for the divalent ion, Ca(2+). The effects are particularly pronounced at high pH. Furthermore, the antimicrobial effect obtained from the combination of fatty acid and tetramethylthiuramdisulfide is significantly enhanced in the presence of 0.1 and 0.2% KCl.

Anti-Infective Agents↗
PubMed1975

Antimicrobial effect of simple lipids with different branches at the methyl end group.

Various fatty acids of branched nature possess fungistatic and bacteriostatic properties. Some of these, particularly those of iso-configuration, strongly enhance the effect of conventional antimicrobial agents that act inside the cell membrane. A relation between this biological effect and the collapse properties of the corresponding monomolecular surface film on water has been observed. In this work, a series of fatty acids with a slightly smaller end group than iso-propyl, the omega-cyclopropane fatty acids, as well as one possessing a somewhat larger end group, the neo-branched fatty acids, have been examined. The omega-cyclopropane fatty acids were found to be more fungistatic than the iso-acids studied earlier. Furthermore, both cyclopropane and neo-fatty acids of short chain lengths exhibited synergistic effects in combination with tetramethylthiuramdisulfide.

Anti-Bacterial Agents↗