Impact on quality of life of an intervention providing additional information to patients with allergic contact dermatitis; a randomized clinical trial

BACKGROUND

Allergic contact dermatitis can negatively impact an individual's daily life in terms of work and interpersonal relationships. Patch-tested individuals show an improved quality of life (QoL).

OBJECTIVES

We aimed to assess the impact on QoL after patch testing and what value an intervention would have on QoL.

METHODS

Dermatology Quality of Life Index (DLQI) were assessed in participants with positive patch test reaction. The participants were randomized, in parallel design, into two groups that received either standard information (controls, n = 70) or a reminder letter in addition to standard information (intervention group, n = 66), ClinicalTrials.gov NCT01953380.

RESULTS

The response rate was 74% (n = 136). The DLQI score was significantly lower 1 year after patch testing in comparison with baseline in the entire group (mean DLQI 6.3 and 4.5 respectively, 95% CI 0.93-2.72, P < 0.001). However, linear regression analyses showed no significant differences in DLQI score at follow-up between the intervention and control groups. Neither age nor gender had impact on DLQI score.

CONCLUSION

There was an improvement of QoL at follow-up in the entire group. However, the intervention performed did not show any significantly greater improvement concerning QoL. Further research is needed to understand what factors apart from patch testing and medical care may affect QoL in patients with contact dermatitis, and what interventions are needed to improve QoL.

Intervention study to evaluate the importance of information given to patients with contact allergy: a randomized, investigator-blinded clinical trial

BACKGROUND

In contact dermatitis, it is crucial to understand and remember the outcome of patch testing. Unfortunately, many patients do not remember the results of their patch tests.

OBJECTIVES

Our aim was to evaluate the effects of an intervention programme in which extensive information on specific contact allergy was provided, in individuals with positive patch test reactions.

METHODS

The study was designed as a randomized, investigator-blinded clinical trial. Participants with positive test reactions were randomized into two groups that received either standard information according to clinical routine or standard information and a reminder letter. Knowledge of contact allergies was evaluated using questionnaires 12 months after inclusion.

RESULTS

There were 184 adults included in the trial and the response rate at 1-year follow-up was 78% (143 of 184). Sixty-five per cent (45 of 69) in the intervention group and 54% (40 of 74) in the control group reported the correct name of the allergen (P = 0·23). Participants with several - as opposed to few - positive patch test reactions had difficulty in remembering the correct names of the allergens (P = 0·001). Moreover, the type of allergy had an influence on their ability to remember the name of the allergen correctly and their ability to make changes in lifestyle.

CONCLUSIONS

The intervention performed did not significantly affect the participants' ability to remember their contact allergy. To achieve better knowledge and changes in lifestyle, efforts to inform should concentrate on individuals with several positive patch test reactions, those with particular allergens, individuals over 60 years of age, and - concerning changes in lifestyle - males.

Antibacterial and antibiofilm effects of sodium hypochlorite against Staphylococcus aureus isolates derived from patients with atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is characterized by an increased susceptibility to skin infections. Staphylococcus aureus is reported to dominate in AD lesions and reports have revealed the presence of staphylococcal biofilms. These infections contribute to aggravation of the eczema. Sodium hypochlorite is known to reduce bacterial load of skin lesions, as well as disease severity, in patients with AD, but the effect on biofilms is unknown.

OBJECTIVES

To investigate the antimicrobial and antibiofilm effects of sodium hypochlorite against S. aureus isolates derived from patients with AD.

METHODS

Skin biopsies derived from patients with infected AD were examined by scanning electron microscopy (SEM). Using radial diffusion assays, biofilm assays and confocal laser scanning microscopy, we assessed the effect of sodium hypochlorite on S. aureus isolates derived from lesional skin of patients with AD.

RESULTS

SEM revealed clusters of coccoid bacteria embedded in fibrin and extracellular substances at the skin of a patient with infected AD. At concentrations of 0·01-0·08%, sodium hypochlorite showed antibacterial effects against planktonic cells. Eradication of S. aureus biofilms in vitro was observed in concentrations ranging from 0·01% to 0·16%. Confocal laser scanning microscopy confirmed these results. Finally, when human AD skin was subjected to sodium hypochlorite in an ex vivo model, a dose of 0·04% reduced the bacteria derived from AD skin.

CONCLUSIONS

Sodium hypochlorite has antimicrobial and antibiofilm effects against clinical S. aureus isolates. Our findings suggest usage of a higher concentration than currently used in bleach baths of patients with skin-infected AD.

Characterization of the interactions of a polycationic, amphiphilic, terminally branched oligopeptide with lipid A and lipopolysaccharide from the deep rough mutant of Salmonella minnesota

The lipid A and lipopolysaccharide (LPS) binding and neutralizing activities of a synthetic, polycationic, amphiphilic peptide were studied. The branched peptide, designed as a functional analog of polymyxin B, has a six residue hydrophobic sequence, bearing at its N-terminus a penultimate lysine residue whose α- and E-amino groups are coupled to two terminal lysine residues. In fluorescence spectroscopic studies designed to examine relative affinities of binding to the toxin, neutralization of surface charge and fluidization of the acyl domains, the peptide was active, closely resembling the effects of polymyxin B and its nonapeptide derivative; however, the synthetic peptide does not induce phase transitions in LPS aggregates as do polymyxin B and polymyxin B nonapeptide. The peptide was also comparable with polymyxin B in its ability to inhibit LPS-mediated IL-1 and IL-6 release from human peripheral blood mononuclear cells. The synthetic compound is devoid of antibacterial activities and did not induce conductance fluxes in LPS-containing asymmetric planar membranes. These results strengthen the premise that basicity and amphiphilicity are necessary and sufficient physical properties that ascribe endotoxin binding and neutralizing activities, and further suggest that antibacterial/membrane perturbant and LPS neutralizing activities are dissociable, which may be of value in designing LPS-sequestering agents of low toxicity.

Transient receptor potential vanilloid 1, vanilloid 2 and melastatin 8 immunoreactive nerve fibers in human skin from individuals with and without Norrbottnian congenital insensitivity to pain

Transient receptor potential vanilloid 1 (TRPV1), vanilloid 2 (TRPV2) and melastatin 8 (TRPM8) are thermosensitive cation channels expressed on primary sensory neurons. In contrast to TRPV1, which is present on nociceptive primary afferents and keratinocytes in human skin, less is known about the distribution of TRPV2 and TRPM8 in this tissue. Immunohistochemistry of human forearm skin identified TRPV2 and TRPM8 immunoreactive nerve fibers in epidermis-papillary dermis and around blood vessels and hair follicles in dermis, although these nerve fibers were less abundant than TRPV1 immunoreactive nerve fibers throughout the skin. The TRPV2 and TRPM8 immunoreactive nerve fibers also showed immunoreactivity for calcitonin gene-related peptide (CGRP) and to a lesser extent substance P (SP). Neither of the TRP ion channels co-localized with neurofilament 200 kDa (NF200), vasoactive intestinal peptide (VIP) or tyrosine hydroxylase (TH). Nerve fibers immunoreactive for TRPV1, TRPV2, TRPM8, CGRP and SP were absent or substantially reduced in number in individuals with Norrbottnian congenital insensitivity to pain, an autosomal disease selectively affecting the development of C-fiber and Adelta-fiber primary afferents. Quantitative real time PCR detected mRNA transcripts encoding TRPV1 and TRPV2, but not TRPM8, in skin from healthy volunteers, suggesting that these ion channels are also expressed extraneuronally. In conclusion, nerve fibers in human skin express TRPV1, TRPV2 and TRPM8 that co-localize with the sensory neuropeptides CGRP and SP, but not with NF200, VIP or TH. A dramatic loss of such nerve fibers was seen in skin from individuals with Norrbottnian congenital insensitivity to pain, further suggesting that these ion channels are expressed primarily on nociceptive primary sensory neurons in human skin.

Glycosaminoglycans inhibit the antibacterial activity of LL-37 in biological fluids

OBJECTIVES

The antibacterial activity of antimicrobial peptides is influenced by various factors such as salt content, pH and the presence of proteins. In this study, we explored the antibacterial action of the human cathelicidin LL-37 in physiologically relevant conditions, i.e. various human wound fluids, human plasma fractions and serum.

METHODS

Radial diffusion assays using Staphylococcus aureus and Escherichia coli were employed for the study of antibacterial effects of LL-37 in the presence of 12 different wound fluids, citrate-, heparin- or EDTA-plasma, or human serum. Glycosaminoglycan content of wound fluids was determined by an Alcian Blue-binding assay. Protein content of wound fluids was measured by the Bradford method. A slot-binding assay was used to study the effects of inhibitors on the interaction between LL-37 and glycosaminoglycans.

RESULTS

Five of twelve wound fluids derived from acute wounds showed marked inhibitory effects on the antibacterial action of LL-37. The inhibition was significantly correlated with high glycosaminoglycan content in wound fluid. Analogous to these findings, heparin-plasma strongly inhibited the antibacterial effect of LL-37. The interaction between LL-37 and glycosaminoglycans was abrogated by the cationic polymers DEAE-dextran and chitosan, yielding increased activity of LL-37.

CONCLUSIONS

Glycosaminoglycan-rich biological fluids inhibit the antibacterial effects of LL-37. Furthermore, polycations that bind to glycosaminoglycans increase the antibacterial activities of endogenous antimicrobial peptides in glycosaminoglycan-containing biological fluids.

Pseudomonas aeruginosa-induced infection and degradation of human wound fluid and skin proteins ex vivo are eradicated by a synthetic cationic polymer

OBJECTIVES

Antimicrobial peptides are important effectors of innate immunity. Bacteria display multiple defence mechanisms against these peptides. For example, Pseudomonas aeruginosa releases potent proteinases that inactivate the human cathelicidin LL-37. Hence, in conditions characterized by persistent bacterial colonization, such as in P. aeruginosa-infected skin wounds, there is a need for efficient means of reducing bacterial load. Here, the effect of the cationic molecule polyhexamethylenebiguanide (PHMB) was evaluated.

METHODS

Infection models in human wound fluid and human skin were established. Radial diffusion methods, bacterial growth and bactericidal assays were used for determination of effects of PHMB on bacteria in the presence of plasma, wound fluid or human skin. At the protein and tissue levels, SDS-PAGE, light microscopy and scanning electron microscopy were used to study the effects of P. aeruginosa infection before and after addition of PHMB.

RESULTS

PHMB killed common ulcer-derived bacteria in the presence of human wound fluid. Furthermore, elastase-expressing P. aeruginosa completely degraded wound fluid proteins as well as human skin during infection ex vivo. The infection, and consequent protein degradation, was reversed by PHMB.

CONCLUSIONS

The ex vivo infection models presented here should be helpful in the screening of novel antimicrobials and constitute a prerequisite for future clinical studies.

The characterization of plasma membrane-bound tubulin of cauliflower using Triton X-114 fractionation

The cortical microtubules determine how cellulose microfibrils are deposited in the plant cell wall and are thus important for the control of cell expansion. To understand how microtubules can control microfibril deposition, the components that link the microtubules to the plasma membrane (PM) of plant cells must be isolated. To obtain information on the properties of the tubulin-membrane associations, cauliflower (Brassica oleracea) PM was subjected to Triton X-114 fractionation, and the distribution of alpha- and beta-tubulin was analyzed using immunoblotting. Approximately one-half of the PM-associated tubulin was solubilized by Triton X-114 and 10 to 15% of both alpha- and beta-tubulin was recovered in the detergent phase (indicative of hydrophobic properties) and 30 to 40% was recovered in the aqueous phase. The hydrophobic tubulin could be released from the membrane by high pH extraction with preserved hydrophobicity. A large part of the PM-associated tubulin was found in the Triton-insoluble fraction. When this insoluble material was extracted a second time, a substantial amount of hydrophobic tubulin was released if the salt concentration was increased, suggesting that the hydrophobic tubulin was linked to a high-salt-sensitive protein aggregate that probably includes other components of the cytoskeleton. The hydrophobicity of a fraction of PM-associated tubulin could reflect a direct or indirect interaction of this tubulin with the lipid bilayer or with an integral membrane protein and may represent the anchoring of the cortical microtubules to the PM, a key element in the regulation of cell expansion.

HIV/AIDS--information and knowledge: a comparative study of Kenyan and Swedish teenagers

Knowledge of hiv/aids, exposure to hiv/aids information and appreciation of given information was studied, by a questionnaire, among 326 Kenyan and 146 Swedish teenage school students in 1994. The aim of the study was to examine differences and similarities in knowledge in the two populations and to examine which sources of information about hiv and aids the respondents had been exposed to and which were most appreciated. The overall knowledge about hiv/aids was high but in specific items the knowledge and awareness of different risk behaviours for contracting hiv/aids differed for the Kenyan and Swedish teenagers. The dissemination of hard factual information about hiv/aids has thus been successful in reaching out although not in stopping the spread of hiv/aids. This calls for new strategies in disease prevention and health promotion. Those strategies should focus much more on lifestyle changes. The health care system, the school and the existing strong civil and voluntary information structures have an important role to play in that work.

Chemical characterization of lipopolysaccharides from Legionella feeleii, Legionella hackeliae and Legionella jordanis

Lipopolysaccharides (LPS) from Legionella feeleii serogroup 1, L. hackeliae serogroup 1 and L. jordanis were subjected to chemical analysis. All three LPS contained D-mannose, D-glucose, D-glucosamine, L-glycero-D-manno-heptose, 2-keto-3-deoxyoctonic acid and glycerol. In addition the LPS of L. feeleii was characterized by L-quinovose (tentatively identified) and L-fucosamine, L. hackeliae LPS by D-quinovosamine, D-galactosamine and D-galacturonic acid, and L. jordanis LPS by D-quinovosamine. Phosphorylated sugars were detected in all three LPS. The backbone sugar of the lipid A part was in each case 2,3-diamino-2,3-dideoxy-D-glucose substituted with a complex pattern of fatty acid, including 20-22 different amide-linked (non-branched and methyl-branched) 3-hydroxy fatty acids of chain-length ranging from 12 to 23 carbon atoms. The fatty acid patterns included also ester-linked nonhydroxylated entities and the uncommon 27-oxo-octacosanoic acid and 29-oxotriacontanoic acid. The LPS of L. hackeliae and L. jordanis also contained heptacosane-1,27-dioic and nonacosane-1,29-dioic acid, and their 2-hydroxy analogues were characteristic of L. jordanis LPS. SDS-PAGE patterns of the three LPS were distinctly different. Both L. feeleii and L. jordanis produced smooth-form LPS with characteristic ladder patterns, whereas L. hackeliae LPS were of more rough-type character.

Chemical composition of lipopolysaccharides from Legionella bozemanii and Legionella longbeachae

Lipopolysaccharides (LPS) from Legionella bozemanii serogroup 1 and Legionella longbeachae serogroup 1 were subjected to chemical analyses. The lipid A part of both LPSs contained 2,3-dideoxy-2,3-diamino-D-glucose as major constituents and D-glucosamine and glycerol as minor constituents of the sugar backbone structure. Both LPSs exhibited a very complex fatty acid composition. Twenty amide-linked 3-hydroxy fatty acids were detected in LPS of L. longbeachae, whereas seventeen were encountered in LPS of L. bozemanii. Both LPSs contained nine ester-linked nonhydroxy fatty acids and the unique long-chain fatty acids 27-oxo-octacosanoic acid, 29-oxo-triacontanoic acid, heptacosane-1,27-dioic acid and nonacosane-1, 29-dioic acid. SDS-PAGE showed that L. bozemanii produced smooth-form LPS, whereas L. longbeachae LPS was mainly of the R-type. Composition analyses were in accordance with these electrophoretic patterns. D-Quinovosamine and L-fucosamine constituted 80 mol% of the polysaccharide part of L. bozemanii LPS. Other sugars identified were D-glucosamine, D-mannose, D-glucose, L-rhamnose, D-glycero-D-manno-heptose, L-glycero-D-manno-heptose, 2-keto-3-deoxy-octonic acid and glycerol. The polysaccharide chain from LPS of L. longbeachae appeared to be shorter, but composed of the same sugars except L-fucosamine. Both LPSs contained glycerol phosphate and glucosamine phosphate and L. longbeachae LPS contained in addition glucose phosphate.

Lipopolysaccharides of Legionella erythra and Legionella oakridgensis

The chemical composition of lipopolysaccharides from Legionella erythra and Legionella oakridgensis was analysed. Sodium dodecyl sulfate polyacrylamide gel electrophoresis showed both lipopolysaccharides to have a smooth-type character. The polysaccharide part of both lipopolysaccharides contained D-mannose, D-glucose, D-glycero-D-mannoheptose, L-glycero-D-manno-heptose, 2-keto-3-deoxyoctonic acid, L-fucosamine, D-glucosamine, and glucosamine phosphate. In addition, L-rhamnose, glycerol phosphate, and glucose phosphate were identified in the polysaccharide part of L. erythra lipopolysaccharide. The main sugar identified in the lipid A part of both lipopolysaccharides, 2,3-diamino-2,3-dideoxy-D-glucose, was found to be substituted with a complex fatty acid composition including at least 16 different amide-linked 3-hydroxy fatty acids. Both lipopolysaccharides contained nonhydroxy fatty acids and the uncommon 27-oxo-octacosanoic acid, 29-oxotriacontanoic acid, and 27-hydroxyoctacosanoic acid. The lipopolysaccharide of L. oakridgensis also contained 29-hydroxytriacontanoic acid. The dioic long-chain acids heptacosane-1,27-dioic acid and nonacosane-1,29-dioic acid were only present in the lipopolysaccharide of L. erythra.

Composition of 2,3-dihydroxy fatty acid-containing lipopolysaccharides from Legionella israelensis, Legionella maceachernii and Legionella micdadei

Lipopolysaccharides (LPS) from Legionella israelensis, L. maceachernii and L. micdadei were analysed for chemical composition. The main sugar of the lipid A fractions was in each case 2,3-diamino-2,3-dideoxy-D-glucose. Lipid A of L. israelensis also contained a substantial amount of D-glucosamine. In each lipid A fraction a complex fatty acid pattern was detected. This comprised at least 19 different 3-hydroxy fatty acids (amide-linked), three 2,3-dihydroxy fatty acids (amide-linked), non-hydroxy fatty acids (ester-linked) as well as long-chain (omega-1)-oxo, (omega-1)-hydroxy and (1,omega)-dioic fatty acids (ester-linked). In addition, L. maceachernii and L. micdadei contained alpha-hydroxylated long-chain (omega-1)-oxo and (1,omega)-dioic fatty acids. The polysaccharide parts of L. maceachernii and L. micdadei LPS were similar and contained mainly L-rhamnose, L-fucose, D-mannose, D-glucose, L-fucosamine, D-glucosamine, 2-keto-3-deoxy-octonic acid (Kdo) as well as the rare octose yersiniose A. The corresponding composition of L. israelensis LPS was simpler and consisted mainly of L-rhamnose and 3-amino-3,6-dideoxy-D-mannose. LPS of L. israelensis and L. micdadei contained, in addition, 2-keto-octonic acid linked to Kdo. Phosphorylated sugar constituents were detected in all three LPS, whereas ethanolamine was found only in LPS from L. maceachernii. The SDS-PAGE band pattern of L. micdadei differed from the two others in a higher proportion of the low molecular mass constituents.

Pseudomonas aeruginosa AlgG is a polymer level alginate C5-mannuronan epimerase

Alginate is a viscous extracellular polymer produced by mucoid strains of Pseudomonas aeruginosa that cause chronic pulmonary infections in patients with cystic fibrosis. Alginate is polymerized from GDP-mannuronate to a linear polymer of beta-1-4-linked residues of D-mannuronate and its C5-epimer, L-guluronate. We previously identified a gene called algG in the alginate biosynthetic operon that is required for incorporation of L-guluronate residues into alginate. In this study, we tested the hypothesis that the product of algG is a C5-epimerase that directly converts D-mannuronate to L-guluronate. The DNA sequence of algG was determined, and an open reading frame encoding a protein (AlgG) of approximately 60 kDa was identified. The inferred amino terminus of AlgG protein contained a putative signal sequence of 35 amino acids. Expression of algG in Escherichia coli demonstrated both 60-kDa pre-AlgG and 55-kDa mature AlgG proteins, the latter of which was localized to the periplasm. An N-terminal analysis of AlgG showed that the signal sequence was removed in the mature form. Pulse-chase experiments in both E. coli and P. aeruginosa provided evidence for conversion of the 60- to the 55-kDa size in vivo. Expression of algG from a plasmid inan algG (i.e., polymannuronate-producing) mutant of P. aeruginosa restored production of an alginate containing L-guluronate residues. The observation that AlgG is apparently processed and exported from the cytoplasm suggested that it may act as a polymer-level mannuronan C5-epimerase. An in vitro assay for mannuronan C5 epimerization was developed wherein extracts of E. coli expressing high levels of AlgG were incubated with polymannuronate. Epimerization of D-mannuronate to L-guluronate residues in the polymer was detected enzymatically, using a L-guluronate-specific alginate lyase of Klebsiella aerogenes. Epimerization was also detected in the in vitro reaction between recombinant AlgG and poly-D-mannuronate, using high-performance anion-exchange chromatography. The epimerization reaction was detected only when acetyl groups were removed from the poly-D-mannuronate substrate, suggesting that AlgG epimerization activity in vivo may be sensitive to acetylation of the D-mannuronan residues. These results demonstrate that AlgG has polymer-level mannuronan C5-epimerase activity.

Detection of Legionella pneumophila in biofilms containing a complex microbial consortium by gas chromatography-mass spectrometry analysis of genus-specific hydroxy fatty acids

A gas chromatographic-mass spectrometric method was used to detect Legionella pneumophila in biofilms in potable water containing a complex microbial consortium. The unique 3-hydroxy and 2,3-dihydroxy fatty acids of the L. pneumophila lipopolysaccharides (LPS) were detected in both the planktonic phase of the continuous culture model and in the biofilms forming on both copper and polyethylene substrata. The technique confirmed that lower numbers of Legionella colonised and grew on copper in comparison to polyethylene and offers promise for routine detection of Legionella in biofilms in the environment.

Hydroxy-fatty acid profiles of Legionella species: diagnostic usefulness assessed by principal component analysis

Twenty-nine species (76 strains) of members of the genus Legionella were analyzed for their cellular hydroxylated fatty acids (OH-FAs). The individual patterns were unusually complex and included both monohydroxylated and dihydroxylated chains of unbranched or branched (iso and anteiso) types. Comparison of the strain profiles by SIMCA (Soft Independent Modelling of Class Analogy) principal component analysis revealed four main groups. Group 1 included Legionella pneumophila plus L. israelensis strains, and group 2 included L. micdadei and L. maceacherneii strains. These two closely related groups were characterized by the occurrence of di-OH-FAs and differed mainly in the amounts of 3-OH-a21:0, 3-OH-n21:0, 3-OH-n22:0, and 3-OH-a23:0. Group 3 (13 species) was distinguished by i14:0 at less than 3%, 3-OH-3-OH-n14:0 at greater than 5%, 3-OH-n15:0 at greater than 2%, and minute amounts of OH-FAs with chains longer than 21:0. Group 4 (12 species) was heterogeneous. Its main characteristics were the presence of 3-OH-n12:0 and 3-OH-n13:0, 3-OH-i14:0 at greater than 5%, as well as significant amounts of 3-OH-a21:0 and 3-OH-n21:0. The groupings obtained by OH-FA profiles were found to reflect DNA-DNA homology groupings reasonably well, and the profiles appear to be useful for differentiation of Legionella species.

Long-chain alpha-hydroxy-(omega-1)-oxo fatty acids and alpha-hydroxy-1,omega-dioic fatty acids are cell wall constituents of Legionella (L. jordanis, L. maceachernii and L. micdadei)

Four long-chain fatty acids, 2-hydroxy-27-oxo-octacosanoic acid (n28:0(2-OH,27-oxo)), 2-hydroxy-29-oxo-triacontanoic acid (n30:0(2-OH,29-oxo)), 2-hydroxy-heptacosane-1,27-dioic acid (27:0(2-OH)-dioic) and 2-hydroxy-nonacosane-1,29-dioic acid (29:0(2-OH)-dioic) were identified by GLC-MS analysis in the phenol-chloroform-petroleum ether (PCP) extracts of Legionella jordanis, L. maceachernii and L. micdadei indicating that they are constituents of lipopolysaccharide. Moreover, five long-chain fatty acids (28:0(27-OH), 28:0(27-oxo), 30:0(29-oxo), 27:0-dioic and 29:0-dioic) previously identified in L. pneumophila (Moll, H. et al., FEMS Microbiol. Lett., 97 (1992), 1-6) were also found in these species. This is to our knowledge the first report on the existence of long chain 2-hydroxylated (omega-1)-oxo fatty acids and 2-hydroxylated 1,omega-dioic fatty acids.

Identification of 27-oxo-octacosanoic acid and heptacosane-1,27-dioic acid in Legionella pneumophila

Two long-chain fatty acids, 27-oxo-octacosanoic acid (28:0(27-oxo)) and heptacosane-1,27-dioic acid (27:0-dioic) were identified for the first time in phenol-chloroform-petroleum ether extracts of Legionella pneumophila, indicating that they are constituents of lipopolysaccharide. The fatty acids were characterised by combined gas-liquid chromatography/mass spectrometry and proton nuclear magnetic resonance spectroscopy. Moreover, minor amounts of 29-oxo-triacontanoic (30:0(29-oxo)) acid and nonacosane-1,29-dioic acid (29:0-dioic) as well as 27-hydroxy-octacosanoic acid (28:0(27-OH)) were present in the phenol-chloroform-petroleum ether extract.

Bile increases lipopolysaccharide release in experimental E. coli peritonitis

Previous studies in rats showed increased mortality when bile was added to intraperitoneally injected Escherichia coli. In the present study bacterial counts and levels of lipo-polysaccharide (LPS) were determined in the peritoneal cavity and in blood 0.5, 1, 4 and 10 hours after induction of peritonitis with E. coli alone or together with bile. LPS was measured with gas chromatographic analysis of beta-hydroxymyristic acid, a characteristic component of E. coli-LPS. Bacterial counts and LPS levels in peritoneal fluid and blood rose higher in E. coli + bile peritonitis than in E. coli peritonitis. The intergroup difference in LPS levels was evident at 0.5 and 1 hour, whereas the bacterial counts began to differ at 2 hours. Presence of intraperitoneal bile in E. coli peritonitis thus produced rapid rise in LPS levels that could not be caused by bacterial numbers alone. This early load of LPS may help to explain the noxious effect of bile in E. coli peritonitis.

Influence of individual bile acids in Escherichia coli peritonitis

Previous studies have shown that intraperitoneal bile increases bacterial growth and mortality in Escherichia coli peritonitis in the rat. The purpose of the present study was to determine a) the influence of bile acids (cholic, deoxycholic, or chenodeoxycholic) and bilirubin on survival, bacterial growth, and superoxide release by peritoneal phagocytes in this model, and b) the effect of bile acids on bacterial growth and endotoxin release when incubated with E. coli in vitro. Each of the bile acids aggravated the E. coli peritonitis, with increased bacterial counts in the peritoneal cavity and in blood and increased mortality. Deoxycholic acid was the most deleterious of the bile acids, causing suppression of superoxide release by peritoneal phagocytes, like whole bile. In vitro, bile acids did not seem to affect growth of E. coli, but cholic and deoxycholic acid seemed to enhance the release of endotoxin. It is concluded that the bile acids are responsible for the noxious effect of bile in E. coli peritonitis. It is suggested that the detergent properties of bile acids aggravate the peritonitis by solubilizing the cell membranes of both bacteria and phagocytes.

Use of two-dimensional gas chromatography with electron-capture detection for the measurement of lipopolysaccharides in peritoneal fluid and plasma from rats with induced peritonitis

The content of 3-hydroxymyristic acid from Escherichia coli lipopolysaccharide in peritoneal fluid and plasma from rats was determined by two-dimensional gas chromatography with electron-capture detection of the 3-O-pentafluorobenzoyl methyl ester derivative. The detection limit of lipopolysaccharide in peritoneal fluid was 3 ng/ml. An experimental model of E. coli peritonitis in the rat was used, with and without coinjection of bile. The concentrations of lipopolysaccharide were highest in both peritoneal fluid and plasma samples from rats injected with E. coli and bile, reaching a maximum 1 h after injection by the gas chromatographic method. Corresponding Limulus assay results for peritoneal samples showed a small increase of lipopolysaccharide concentrations during the first 4 h after injection, followed by a substantial increase. The results indicate that bile salts cause an increased release of lipopolysaccharide from gram-negative bacterial cells in vivo and that this may be responsible for the high mortality caused by peritonitis. In contrast to the Limulus assay, gas chromatography enables the total amount of lipopolysaccharide in a clinical sample to be determined.

Comparison of the limulus amebocyte lysate test and gas chromatography-mass spectrometry for measuring lipopolysaccharides (endotoxins) in airborne dust from poultry-processing industries

The lipopolysaccharide (endotoxin) content in airborne dust samples from three different poultry slaughterhouses was determined with both the chromogenic Limulus amebocyte lysate assay and gas chromatography-mass spectrometry analysis of lipopolysaccharide-derived 3-hydroxy fatty acids. Gram-negative cell walls were also measured by using two-dimensional gas chromatography/electron-capture analysis of diaminopimelic acid originating from the peptidoglycan. The correlation between the results of the Limulus assay and those of gas chromatography-mass spectrometry for determination of the lipopolysaccharide content in the dust samples was poor, whereas a good correlation was obtained between lipopolysaccharide and diaminopimelic acid concentrations with the gas chromatographic methods. The results suggest that it is predominantly cell-wall-dissociated lipopolysaccharides that are measured with the Limulus assay, whereas the gas chromatographic methods allow determination of total concentrations of lipopolysaccharide, including Limulus-inactive lipopolysaccharide, gram-negative cells, and cellular debris.

Chemical composition of a lipopolysaccharide from Legionella pneumophila

Lipopolysaccharide isolated from Legionella pneumophila (Phil. 1) was examined for chemical composition. The polysaccharide split off by mild acid hydrolysis contained rhamnose, mannose, glucose, quinovosamine, glucosamine and 2-keto-3-deoxyoctonate, in molar proportions 1.6:1.8:1.0:1.5:4.1:2.7. Heptoses were absent and glucose was probably mainly phosphorylated. The carbohydrate backbone of the lipid A part consisted of glucosamine, quinovosamine and glycerol, in the molar ratios 3.9:1.0:3.4, with glycerol as a phosphorylated moiety. A complex fatty acid substitution pattern comprising eight O-ester-linked, exclusively nonhydroxylated acids, and nineteen amide-linked, exclusively 3-hydroxylated acids was revealed. Both straight- and branched (iso and anteiso) carbon chains occurred. The major hydroxy fatty acid was 3-hydroxy-12-methyltridecanoic acid and six others were of a chain-length above 20 carbon atoms, with 3-hydroxy-20-methyldocosanoic acid as the longest. Two dihydroxy fatty acids, 2,3-dihydroxy-12-methyltridecanoic and 2,3-dihydroxytetradecanoic acids, were also detected. These results suggest that L. pneumophila contains a rather complex and unusual lipopolysaccharide structure of considerable biological and chemotaxonomic interest.

Two-dimensional gas chromatography with electron capture detection for the sensitive determination of specific mycobacterial lipid constituents

A method was developed for determining two characteristic mycobacterial lipid constituents, tuberculostearic acid (as its pentafluorobenzyl ester) and 2-eicosanol (as its pentafluorobenzoyl ester), by using gas chromatography with electron capture detection. A microprocessor-controlled column-switching system (two-dimensional gas chromatography) facilitated sample preparation and increased specificity. The usefulness of the technique was illustrated by its ability to reveal picogram amounts of tuberculostearate in a suspension of Mycobacterium leprae isolated from a naturally infected armadillo. Two-dimensional gas chromatography with electron capture detection may in some instances provide a convenient alternative to gas chromatography-mass spectrometry for use in demonstrating the presence of mycobacteria in a complex environment.

Two-dimensional gas chromatography with electron-capture detection used in the determination of specific peptidoglycan and lipopolysaccharide constituents of gram-negative bacteria in infected human urine

Gas chromatography with electron-capture detection was used in the determination of diaminopimelic acid (as the N-heptafluorobutyryl isobutyl derivative) and 3-hydroxymyristic acid (as the O-pentafluorobenzoyl methyl derivative) in Gram-negative bacterial cells in infected human urine. Use of the column-switching (two-dimensional gas chromatography) technique greatly enhanced the selectivity of the detection and simplified the processing of samples. The system described should prove useful for trace detection of specific bacterial constituents in complex environments.

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.

Gas chromatographic determination of (phosphorylated) 2-keto-3-deoxyoctonic acid, heptoses and glucosamine in bacterial lipopolysaccharides after treatment with hydrofluoric acid, methanolysis and trifluoroacetylation

Quantification of phosphorylated sugar constituents of lipopolysaccharides has been performed by the following sequence: dephosphorylation by treatment with hydrofluoric acid, cleavage to monomeric constituents by methanolysis and analysis of the released sugars by capillary gas chromatography. Lipopolysaccharides of Salmonella minnesota Rd1P+, Bordetella pertussis NIH 114 and Vibrio cholerae, NAG and 95R strains, were used as model substances. Comparison of the chromatographic data obtained from hydrofluoric acid-treated and untreated lipopolysaccharide preparations indicated that all lipopolysaccharides examined contained one moiety of glucosamine bound to phosphate in a stable linkage. 2-Keto-3-deoxyoctonic acid appeared phosphorylated to a variable extent. Lipopolysaccharides of the two V. cholerae strains contained one moiety of fully phosphorylated 2-keto-3-deoxyoctonic acid, whereas in that of S. minnesota Rd1P+ only one of the three moieties was phosphorylated. Lipopolysaccharide of B. pertussis had one moiety of 2-keto-3-deoxyoctonic acid, ca. 70% phosphorylated. All four of the preparations examined contained L-glycero-D-manno-heptose in amounts varying from 2.6 to 5.2 moieties. In the lipopolysaccharides of B. pertussis and strain 95R of V. cholerae this sugar was unphosphorylated, whereas the two remaining strains contained one phosphorylated moiety of this sugar. Phosphorylated lipopolysaccharide constituents can be analysed by this approach on a 50-100 micrograms scale.

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.

Ultrasensitive analysis of microbial fatty acids using gas chromatography with electron capture detection

Pentafluorobenzyl and pentafluoropropionyl/pentafluorobenzyl esters of bacterial fatty acids were analysed by capillary gas chromatography using both flame ionization and electron capture detection. No differences between the relative peak areas of the various fatty acids were observed as regards the two detectors used except that response of the electron capture dectector to the hydroxy acid derivatives exceeded that to the non-hydroxy acid derivatives by 20%. Use of the described derivatives in combination with electron capture detection yields chromatograms comparable with those obtained by analysis of methyl esters using flame ionization detection but with superior sensitivity.

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.