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Biomedical subjects

A Fox

Publications and source records attributed to A Fox.

At least 127 records · Page 7Linked to original sources
PubMed1991

Rapid elimination of a synthetic adjuvant peptide from the circulation after systemic administration and absence of detectable natural muramyl peptides in normal serum at current analytical limits.

Although it is clear that muramyl peptides are involved in sleep associated with bacterial infection, their role in normal physiological sleep is less certain. It has been speculated that "natural" muramyl peptides, derived from degraded gut flora, may pass into the bloodstream, where they play a role in normal sleep (M. Karnovsky, Fed. Proc. 45:2556-2560, 1986). Muramic acid serves as a chemical marker for muramyl peptides, since it is not synthesized by mammals. After injection of synthetic muramyl dipeptide in rabbits, muramic acid was readily detected (after release by acid hydrolysis) in the circulation; however, levels rapidly decreased. This was an important positive control in assessing circulating levels of natural muramyl peptides. Muramic acid was not found in normal serum (detection limit, approximately 500 pmol/ml), demonstrating the absence of appreciable amounts of circulating natural muramyl peptides. At this time we are unable to provide supportive evidence for Karnovsky's hypothesis.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1991

Combined endovascular embolization and surgery in the management of cerebral arteriovenous malformations: experience with 101 cases.

The authors describe their experience with 101 cerebral arteriovenous malformations (AVM's) treated by endovascular embolization followed by surgical removal. Fifty-three patients presented with intracranial hemorrhage and 35 had seizures. Based on the classification of Spetzler and Martin, two AVM's were Grade I, 13 were Grade II, 26 were Grade III, 43 were Grade IV, and 17 were Grade V. Fifty-six AVM's were in the right hemisphere, 28 were in the left hemisphere, 12 were in the corpus callosum, and five involved the cerebellum. In 50 cases, presurgical obliteration of 50% to 75% of the AVM nidus was achieved by embolization, and in 31 cases this percentage increased to between 75% and 90%. In 97 (96%) patients, complete surgical removal of the AVM was obtained. Morbidity resulting from preoperative endovascular embolization was classified as mild in 3.9% of the cases, moderate in 6.9%, and severe in 1.98%. The death rate related to embolization was 0.9%. The immediate postsurgical morbidity was classified as mild in 5.9% of the cases, moderate in 10.8%, and severe in 5.9%. The overall long-term morbidity was mild in 5.9% of the cases, moderate in 6.9%, and severe in 1.98%. Two patients (1.98%) died due to intractable intraoperative hemorrhage and two (1.98%) as a result of postsurgical pulmonary complications.

Adolescent↗
PubMed1990

Modulation of the blood-aqueous barrier by gram positive and gram negative bacterial cell wall components in the rat and rabbit.

Acute anterior uveitis in man is related to Gram negative bacterial infection occurring at sites distant to the eye. This could involve intraocular localization of inflammatory bacterial cell wall constituents. Modulation of the blood-aqueous barrier in rabbit and rat, by muramyl dipeptide (the monomer of peptidoglycan) and lipopolysaccharide (and its monomer lipid A) was studied. The rabbit eye was found to be highly susceptible to MDP and LPS, although without cellular infiltration. In contrast the rat eye was demonstrated to be totally refractory to MDP. The response to LPS in the rat was modest, required high dosages and ocular changes were slow to occur, but cellular infiltration was readily apparent. Since MDP is found in Gram positive (as well as Gram negative) bacterial cell walls it is hypothesized that Gram positive bacteria might also play a role in causing uveitis in man.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1990

An examination of the 5-HT3 receptor mediating contraction and evoked [3H]-acetylcholine release in the guinea-pig ileum.

1. The relative contributions of two classes of 5-hydroxytryptamine (5-HT) receptor (5-HT2 and 5-HT3) to the contractile action of 5-HT, 2-methyl-5-hydroxytryptamine (2-methyl-5-HT) and alpha-methyl-5-hydroxytryptamine (alpha-methyl-5-HT) were studied in the guinea-pig ileum longitudinal muscle-myenteric plexus strip (LMMP) preparation. Contractility studies were combined with an analysis of the effects of the three agonists on [3H]-acetylcholine ([3H]-ACh) release from preparations preincubated with [3H]-choline. 2. In contracting the LMMP, 5-HT was approximately one order of magnitude more active than 2-methyl-5-HT and alpha-methyl-5-HT, with relative activities for 5-HT: 2-methyl-5-HT: alpha-methyl-5-HT of 1.00: 0.13: 0.10. 3. Ketanserin (1 microM) was without effect on the concentration-response curves for concentration to 5-HT. 2-methyl-5-HT or alpha-methyl-5-HT, whilst ondansetron (GR38032F: 1 microM) produced a parallel rightward displacement of the upper part of the concentration-response curves to 5-HT and alpha-methyl-5-HT and of the entire curve to 2-methyl-5-HT. 4. In increasing the spontaneous release of [3H]-ACh from the LMMP, 5-HT was again approximately one order of magnitude more active than 2-methyl-5-HT and alpha-methyl-5-HT with relative activities for 5-HT: 2-methyl-5-HT: alpha-methyl-5-HT of 1.00: 0.19: 0.11. 5. Ondansetron (1 microM) greatly attenuated the increase in spontaneous [3H]-ACh release evoked by all three agonists. pKB estimates of 7.62 + 0.12 and 7.64 + 0.09 were obtained for ondansetron antagonism of 5-HT and 2-methyl-5-HT-evoked increases respectively. 6. These data suggest that the contractile action of 5-HT, 2-methyl-5-HT and a-methyl-5-HT in the guinea-pig ileum can, under these conditions, be accounted for largely in terms of 5-HT3 receptor activation. Estimates for pKB obtained with ondansetron are in accordance with those previously obtained from contractility studies in this preparation and these findings are discussed in terms of the postulated existence of subtypes of 5-HT3 receptors.

Acetylcholine↗
PubMed1990

Role of bacterial debris in inflammatory diseases of the joint and eye.

Several distinct rheumatic conditions (including Lyme arthritis, Reiter's syndrome and rheumatic fever) as well as certain forms of the blinding disease, uveitis, may share a common etiology. In each instance specific bacterial pathogens may infect a distant site, which on interaction with the immune system, leads to a sterile inflammation in the joint or eye. These "reactive" conditions may result, in some cases, from prior localization of non-viable bacterial remnants (including the cell wall or peptidoglycan) or alternatively "dormant" fastidious bacteria in the affected joint or eye where they act as persisting antigens. Classical culture techniques, would not detect the presence of these putative microbial antigens. Alternative approaches for detection of ubiquitous components of bacteria in the host (using appropriate chemical, molecular and immunological techniques) are discussed.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1990

Muramic acid is not detectable in Chlamydia psittaci or Chlamydia trachomatis by gas chromatography-mass spectrometry.

By using the powerful separation technique of capillary gas chromatography combined with the selectivity of mass spectrometric detection, muramic acid was not detectable in purified elementary bodies of Chlamydia psittaci Cal 10 (less than or equal to 0.006%) or C. trachomatis serovar E (less than or equal to 0.02%). This confirms previous reports which suggested the absence of a typical peptidoglycan in Chlamydia spp.

Chlamydia trachomatis↗
PubMed1990

Chemotaxonomic differentiation of legionellae by detection and characterization of aminodideoxyhexoses and other unique sugars using gas chromatography-mass spectrometry.

Legionellae have been differentiated previously by analyzing their carbohydrate contents by gas chromatography with flame ionization detection. In the present study, total ion mode gas chromatography-mass spectrometry (GC-MS) was used to detect a number of unusual sugars, including one that is structurally related to O-methyldideoxyheptoses. Increased sensitivity and selectivity for carbohydrate detection was achieved by selected ion-monitoring GC-MS. Two of the uncommon sugars previously discovered in the legionellae (X1 and X2) were identified as quinovosamine and fucosamine, respectively. Legionella pneumophila contained rhamnose and quinovosamine but not the quinovosamine isomer fucosamine. Tatlockia micdadei and Legionella maceachernii contained large amounts of rhamnose, fucose, and fucosamine but not quinovosamine. These two species were the only legionellae studied that contained another unusual sugar that is referred to as X3, pending determination of its structure. Fluoribacter dumoffi, Fluoribacter bozemanae, and Legionella anisa were varied in their carbohydrate contents, both within and between species, but could be distinguished from L. pneumophila and the T. micdadei and L. maceachernii group. Fluoribacter gormanii was unique among the legionellae in that it lacked both quinovosamine and fucosamine. Legionella jordanis contained other unusual carbohydrates in addition to quinovosamine. GC-MS may have wide application in the differentiation of bacterial species.

Amino Sugars↗
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↗
PubMed1989

Mass spectrometric quantitation of muramic acid, a bacterial cell wall component, in septic synovial fluids.

This is the first report describing the use of gas chromatography-mass spectrometry for detection of muramic acid in infected synovial fluid (SF). Muramic acid is a ubiquitous component of bacterial cell walls, and it has been proposed that it could serve as a chemical marker for the presence of live bacteria or bacterial debris in rheumatoid joints. Our goal was to determine whether muramic acid was present at detectable levels in septic SF, since this would serve as a positive control for studies of reactive and rheumatoid arthritis. Muramic acid was found to be present at levels of less than 250-1,700 ng/ml in 12 septic SF samples (10 of which were culture positive for Staphylococcus aureus and 1 each for Escherichia coli and Streptococcus pneumoniae). Among these samples, those containing low bacterial colony counts did not contain detectable muramic acid. Muramic acid was also not detected in any SF samples from 20 control patients. We conclude that muramic acid can be used as a marker for the presence of bacterial peptidoglycan in SF. With further lowering of gas chromatography-mass spectrometry detection limits, determination of the quantities of bacterial debris present in joints of patients with rheumatoid or reactive arthritis will be attainable.

Cell Wall↗
PubMed1989

Keratoconjunctivitis sicca with associated secondary uveitis elicited in rats after systemic xylazine/ketamine anesthesia.

The systemic administration of an anesthetic dosage of a combination of xylazine and ketamine hydrochloride produced an acute exposure keratopathy which progressed into a syndrome resembling keratoconjunctivitis sicca. Within a few minutes corneal changes occurred that were characterized by viscous mucus, loss of corneal luster and dryness. Other acute but transient changes included development of cataracts, mydriasis and proptosis. Progressive changes were observed in the cornea within 4 days which lasted at least 8 weeks in some cases, and included punctate epithelial keratopathy progressing to devitalized or keratinized epithelial plaques. Polymorphonuclear cell infiltration of the corneal stroma associated with plaques occurred. Epithelial denudation and neovascularization of the cornea, dilation and engorgement of iridial blood vessels, as well as flare in the anterior chamber were also seen. The ocular lesions induced by xylazine/ketamine should be considered carefully when designing or interpreting research on the anterior segment. Ketamine hydrochloride with sodium pentobarbital produced excellent anesthesia without any significant ocular side-effects and may be preferred in many instances.

Animals↗
PubMed1989

Systemic injection of group A streptococcal peptidoglycan-polysaccharide complexes elicits persistent neutrophilia and monocytosis associated with polyarthritis in rats.

The perpetuation of inflammatory changes within joints elicited by persisting, poorly biodegradable group A streptococcal cell walls (peptidoglycan-polysaccharide complexes [PG-PS]) is well documented. Chronic changes in the bloodstream induced by PG-PS have not been described previously. We demonstrated that leukocytosis occurs within 3 days after intraperitoneal injection of PG-PS and remains elevated 20 weeks later. Chronic neutrophilia, monocytosis, and lymphocytosis were observed in all experiments. Chronic changes in platelet, erythrocyte, and reticulocyte counts were not seen. The newly documented leukocytosis, lasting for months after PG-PS administration, provided a circulating pool of leukocytes that may participate in chronic inflammatory events in the joint. Although the central role of the macrophage in PG-PS-mediated inflammation has been emphasized (F. G. Dalldorf, W. J. Cromartie, S. K. Anderle, R. L. Clark, and J. H. Schwab, Am. J. Pathol. 100:383-402, 1980), the polymorphonuclear cell may be involved in periods of exacerbation of streptococcal cell wall-mediated polyarthritis. This was supported by our observations that neutrophilia and monocytosis correlate well with the degree of chronic joint inflammation.

Animals↗
PubMed1989

[Morbidity-mortality related to domestic accidents in Belgium: Epidemiology and strategy of prevention].

Home accidents, especially those occurring in children in the younger age group, are a considerable concern to the public health authorities. In addition to the informations registered on the death certificates, the EHLASS-program, i.e. European Health and Leisure Accident Surveillance System, was organized since 1986 by the European Community in order to collect data on the morbidity related to this type of accidents. In Belgium, the collection of data started in 1987, and actually four hospitals provide information. Each year, several thousands of cases are reported. This poster will summarize the Belgian situation from the two sources of data. General strategies for prevention of home accidents are proposed, and some types of intervention are suggested.

Accidents, Home↗
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↗
PubMed1988

Analysis of the amino acid and sugar composition of streptococcal cell walls by gas chromatography-mass spectrometry.

A procedure for determining the amino acid and sugar composition of streptococcal peptidoglycan-polysaccharide complexes by capillary gas chromatography-mass spectrometry (GC-MS) was established. Amino acids are analysed as butyl heptafluorobutyl derivatives and sugars as alditol acetates. These two different groups of compounds are derivatized independently but chromatography in both cases utilizes the same OV-1701 fused-silica capillary column which simplifies GC-MS analysis. The butyl heptafluorobutyl procedure incorporates new pre- and post-derivatization clean-up steps. Additionally, selected-ion monitoring MS allows amino acids to be readily analysed without interference from background noise.

Amino Acids↗