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Biomedical subjects

G Odham

Publications and source records attributed to G Odham.

At least 19 recordsLinked to original sources
PubMed1989

D-alanine as a chemical marker for the determination of streptococcal cell wall levels in mammalian tissues by gas chromatography/negative ion chemical ionization mass spectrometry.

A gas chromatography/mass spectrometry method using selected ion monitoring with negative ion detection and methane chemical ionization was employed to quantitate a marker for bacterial peptidoglycan, D-alanine, in mammalian tissues. D-Alanine originating from bacterial peptidoglycan was obscured by substantial amounts of D-alanine generated by racemization from L-alanine present in tissue protein. To overcome this problem, samples were enzymatically treated and hydrolyzed in deuterated hydrochloric acid. Newly formed D-alanine derived from protein was labeled with deuterium and bacterial D-alanine remained unlabeled, enabling differentiation by the molecular weight increase. Butyl heptafluorobutyryl derivatives of the D- and L-amino acids were separated on a fused silica capillary column coated with Chirasil-val. The amounts of bacterial D-alanine found in livers of arthritic rats were consistent with previously reported levels of other carbohydrate-derived markers for bacterial peptidoglycan-polysaccharide complexes.

Alanine↗
PubMed1988

Highly sensitive determination and characterization of intact cellular ester-linked phospholipids using liquid chromatography-plasma spray mass spectrometry.

Liquid chromatographic class separations of common cellular phospholipids combined with plasma spray ionization of the effluents were investigated. Comparison with true thermospray ionization involving ammonium acetate buffering revealed a gain in total ionization in the plasma spray of a factor of approximately 10 using a cation-exchange column and a solvent mixture consisting of acetonitrile-methanol-water (400:100:15, v/v). Plasma spray ionization studies of bovine brain polyphosphoinositides interrelated by the phosphate content in the inositol moiety showed almost identical monoglyceride and diglyceride ion clusters, indicating possibilities of studying the biochemical turnover of such phospholipids. Plasma spray ionization liquid chromatography-mass spectrometry of bacterial membrane phospholipids (Pseudomonas fluorescens) revealed possibilities of obtaining indications of individual fatty acid compositions from the spectra of the phosphatidylinositol and phosphatidylethanolamine fractions present. Conventional gas chromatographic fatty acid analysis agreed with the direct mass spectrometric structure elucidations. Interestingly, the two phospholipid classes had different relative fatty acid compositions with a significantly higher degree of cyclic fatty acids in the phosphatidyl ethanolamines. Plasma spray ionization yielded linear dose-response curves for both the monoglyceride and diglyceride fragment signals in the selected-ion monitoring mode. The detection limit for the monoglyceride and diglyceride species of phosphatidylcholine under the chromatographic and mass spectrometric conditions used was found to be in the picogram range.

Cell Membrane↗
PubMed1988

Determination of environmental levels of peptidoglycan and lipopolysaccharide using gas chromatography with negative-ion chemical-ionization mass spectrometry utilizing bacterial amino acids and hydroxy fatty acids as biomarkers.

D-Alanine and diaminopimelic acid originating from bacterial peptidoglycans and hydroxy fatty acids from lipopolysaccharides (endotoxins) were analysed by gas chromatography using a chiral column (Chirasil-Val as stationary phase) and selected-ion monitoring detection with negative-ion chemical-ionization mass spectrometry. The amino acids were analysed as N-heptafluorobutyryl isobutyl esters after rapid hydrolysis of peptidoglycan followed by isolation of the amino acids with disposable ion-exchange columns. Racemization of amino acid enantiomers was controlled by using deuterium chloride in the hydrolysis. The hydroxy acids were analysed as O-pentafluorobenzoyl methyl esters. Most of the bacteria present in airborne dust from a poultry confinement building were found to be Gram-positive according to the analytical chemical method whereas the Limulus amoebocyte lysate test suggested the presence of appreciable amounts of lipopolysaccharides of Gram-negative bacteria. Further studies are required to compare the utility of these two methods for determining endotoxins in complex environments.

Amino Acids↗
PubMed1987

Determination of endotoxins by gas chromatography: evaluation of electron-capture and negative-ion chemical-ionization mass spectrometric detection of halogenated derivatives of beta-hydroxymyristic acid.

The sensitivity and selectivity of gas chromatography for analysing several halogenated ester derivatives of beta-hydroxymyristic acid were studied using both selected-ion monitoring detection with negative-ion chemical-ionization mass spectrometry and electron-capture detection. Six different derivatization methods were compared with respect to yield, chemical stability and formation of by-products. Procedures for removal of excess reagents using disposable silica columns and thin-layer chromatography were elaborated. The 3-O-pentafluorobenzoyl-methyl ester was the preferred derivative since it provided high sensitivity and had the molecular ion as the base peak in the mass spectrum. The detection limit was 0.5 pg with electron-capture detection and 0.3 pg with the mass spectrometric system. Using beta-hydroxymyristic acid as a chemical marker it was possible to detect Escherichia coli endotoxin in aqueous solution at a level of 1 ng/ml.

Chromatography, Gas↗
PubMed1987

Diagnosis of pulmonary tuberculosis by selected-ion monitoring: improved analysis of tuberculostearate in sputum using negative-ion mass spectrometry.

Coded sputum specimens from patients with tuberculous (8 specimens) and nontuberculous (15 specimens) pneumonia were analyzed for tuberculostearic acid by selected-ion monitoring of the pentafluorobenzyl ester derivative by using negative-ion mass spectrometry. The analytical results agreed with those from culturing of the specimens, except in three cases in which the chromatograms were difficult to interpret owing to insufficient amounts of sputa available. Negative-ion mass spectrometry provided superior sensitivity and selectivity for detection of tuberculostearic acid compared with the previously used gas chromatographic-mass spectrometric methods. The technique reported here should have considerable potential for the rapid diagnosis of pulmonary tuberculosis by direct analysis of sputum.

Gas Chromatography-Mass Spectrometry↗
PubMed1987

Tuberculostearic acid in lymph nodes from patients with sarcoidosis.

It has earlier been suggested that mycobacteria may play an aetiological role in the development of sarcoidosis. To investigate this further we analyzed the presence of a characteristic mycobacterial constituent, tuberculostearic acid (TS, 10-methyloctadecanoic acid), in lymph nodes from 22 patients with sarcoidosis and in eleven children and three adult controls. To detect TS gas chromatography/mass spectrometry was used. These findings were compared with the results from conventional mycobacterial culture and radiometric respirometry. Although the latter techniques failed to detect mycobacteria in all the tested tissue samples, TS was found in various amounts. Thus, 0-3 micrograms TS/g freeze-dried tissue was noted in eight sarcoid patients, 3-50 micrograms TS/g in eight and 51-400 micrograms TS/g in the remaining six patients. Among the controls only 1/14 had detectable TS. In one patient with lymph node tuberculosis TS was in the range 51-400 micrograms/g. We conclude that the findings could be explained by the presence of mycobacteria not cultivable with the studied techniques or with the presence of remnants after an earlier colonisation with mycobacteria, e.g. BCG-vaccination. Mycobacteria or mycobacterial cell-envelope in sarcoid tissue may possibly act as cofactors in the development of the disease, i.e. they might function as triggering agents (adjuvans) of the immune response. On the other hand the findings may be without any aetiological significance. In that latter case a hitherto unknown lack of wax decomposition during several decades has to be considered.

Adult↗
PubMed1985

C15, C20, and C25 isoprenoid homologues in glycerol diether phospholipids of methanogenic archaebacteria.

The glycerol diether phospholipids of 25 monocultures of methanogenic bacteria were isolated and degraded with hydriodic acid. The resulting alkyl iodides were converted to acetate esters and alcohols which were examined using capillary gas-liquid chromatography. The presence of C20 phytanol was observed in accordance with previous studies. Soft fragmentation by chemical ionization mass spectrometry combined with selected ion monitoring enabled the detection, for the first time, of C15 and C25 isoprenologues as components of the diether phospholipids in several strains.

Archaea↗
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↗