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E Tuomanen

Publications and source records attributed to E Tuomanen.

At least 55 records · Page 3Linked to original sources
PubMed1994

Pharmacokinetics of fluconazole in cerebrospinal fluid and serum of rabbits: validation of an animal model used to measure drug concentrations in cerebrospinal fluid.

Complete concentration-time data describing the pharmacokinetics of fluconazole in the cerebrospinal fluid (CSF) following a single dose are not available for humans or animals. We studied the pharmacokinetics of fluconazole with an indwelling intracisternal needle as described by R.G. Dacey and M.A. Sande (Antimicrob. Agents Chemother. 6:437-441, 1974). To determine whether the presence of an intracisternal needle alters pharmacokinetics in the CSF, we validated this model with uninfected rabbits by measuring pharmacokinetic constants following direct intracisternal and intravenous administration of fluconazole. Following direct injection, there was no alteration of elimination rates in the CSF with increasing sample number or time. Following intravenous administration, the penetration and kinetic constants were the same in individual animals from which multiple CSF samples were obtained as in a composite subject constructed by pooling virgin samples from different animals. The presence of the intracisternal needle did not alter CSF chemistry or leukocyte counts, and erythrocyte contamination was < 0.001%. While drug concentrations were measured by a microbiological assay, we also compared the sensitivity and reproducibility of a high-performance liquid chromatography (HPLC) assay with those of the microbiological assay. Following a single intravenous dose, the maximum concentration of the drug in serum, the time to maximum concentration of the drug in serum, the terminal elimination half-life in the CSF, and the percent penetration by fluconazole were 6.12 micrograms/ml, 1 h, 9.0 h, and 84.3%, respectively. We conclude that the sampling of CSF via an indwelling needle does not alter fluconazole pharmacokinetics, cause inflammation, or alter chemical parameters; that the microbiological assay is at least equivalent in sensitivity and reproducibility to the HPLC assay; and that robust parameters describing the pharmacokinetics of fluconazole are possible with this model.

Animals↗
PubMed1993

Ligand specificity of purified complement receptor type three (CD11b/CD18, alpha m beta 2, Mac-1). Indirect effects of an Arg-Gly-Asp (RGD) sequence.

We have purified CR3 to homogeneity by affinity chromatography on C3bi-Sepharose and elution with EDTA. C3bi-coated erythrocytes bound to this purified CR3, and binding was dependent on the concentration of both C3bi and CR3, as well as on temperature and the presence of divalent cations. Moreover, binding could be blocked by mAb against CR3 or C3bi and could be enhanced by the addition of integrin modulating factor-1. We used the purified CR3 to test whether several putative ligands of CR3 directly bound the receptor. The interaction of purified CR3 with fibrinogen, filamentous hemagglutinin of Bordetella pertussis, lipophosphoglycan and glycoprotein 63 of Leishmania mexicana, and lipopolysaccharide from Escherichia coli was confirmed. However the interaction of CR3 with zymosan or its major component, beta-glucan, was not observed in these assays. Previous studies showed that binding of C3bi to PMN could be blocked with Arg-Gly-Asp (RGD) containing peptides and were interpreted to indicate that the RGD sequence in C3bi interacts directly with CR3. We found, however, that RGD containing peptides were unable to block the interaction of C3bi with purified CR3, yet retained the ability to block binding of C3bi to cells. We conclude that RGD-peptides do not directly bind CR3, but instead indirectly effect CR3 function. Inasmuch as the effect of RGD-peptides could be mimicked with antibodies against leukocyte response integrin, we suggest that RGD-peptides may bind to leukocyte response integrin on polymorphonuclear leukocytes and influence CR3 activity via this receptor.

Amino Acid Sequence↗
PubMed1993

Prokaryotic peptides that block leukocyte adherence to selectins.

Pertussis toxin binds target cells through the carbohydrate recognition properties of two subunits, S2 and S3, which share amino acid sequence similarity with the lectin domains of the eukaryotic selectin family. Selectins appear on inflamed endothelial cells and promote rolling of leukocytes by reversibly binding carbohydrates. S2, S3, and synthetic peptides representing their carbohydrate recognition domains competitively inhibited adherence of neutrophils to selectin-coated surfaces and to endothelial cells in vitro. These proteins and peptides also rapidly upregulated the function of the leukocyte integrin CD11b/CD18. These findings implicate mimicry of eukaryotic selectins by prokaryotic adhesive ligands and link the mechanisms underlying leukocyte trafficking to microbial pathogenesis.

Amino Acid Sequence↗
PubMed1993

Attachment factors of Bordetella pertussis: mimicry of eukaryotic cell recognition molecules.

Bacteria localize to specific target organs during infection by recognizing eukaryotic cell surface addresses. This address system exists to facilitate normal trafficking of host cells such as leukocytes. The mechanisms by which bacteria subvert host targeting codes provide a unique link between microbial pathogenesis and eukaryotic cell trafficking, and can point to a new array of antibodies and peptides of potential therapeutic value.

Amino Acid Sequence↗
PubMed1993

The biologic activities of peptidoglycan in experimental Haemophilus influenzae meningitis.

While gram-positive bacterial cell walls are known to incite inflammation, the contribution of gram-negative peptidoglycan to disease has not been characterized. The ability of cell wall, purified peptidoglycan, and soluble peptidoglycan subcomponents from Haemophilus influenzae to provoke inflammation was determined in a rabbit model of meningitis. Haemophilus peptidoglycan, with or without associated proteins, produced brain edema at > or = 0.1 micrograms/mL of cerebrospinal fluid (CSF); leukocytosis and protein accumulation in CSF occurred only at > or = 10.0 micrograms/mL of CSF. Solubilized peptidoglycan was 10-fold more active than intact cell wall. The bioactivity of peptidoglycan from ampicillin-resistant H. influenzae was at least twofold greater than that of ampicillin-sensitive strains. Consistent with these pathologic effects of purified peptidoglycan, ampicillin-induced bacterial lysates in which endotoxin was neutralized induced brain edema and protein influx but little leukocytosis. Thus, peptidoglycan seems to contribute to the pathology of gram-negative meningitis, particularly brain edema.

Ampicillin Resistance↗
PubMed1993

Progression of hearing loss in experimental pneumococcal meningitis: correlation with cerebrospinal fluid cytochemistry.

The development of hearing loss and concomitant cerebrospinal fluid (CSF) cytochemical changes in a model of pneumococcal meningitis were examined. Rabbits were injected intracisternally with 10(5) pneumococci. Auditory evoked potentials to clicks and to 10- and 1-kHz tone bursts were recorded hourly; CSF was analyzed every 4 h. Sensorineural hearing loss developed in all animals beginning 12 h after infection and progressed to severe deafness. The onset of hearing loss was preceded by a CSF leukocytosis of > 2000 cells/microL and elevation of CSF protein and lactate concentrations to > or = 1 mg/mL. Temporal bone histopathology showed pneumococci and leukocytes extending from the CSF to the perilymph via the cochlear aqueduct. Hearing loss can develop early in the course of meningitis and is preceded by the abrupt onset of inflammatory changes in CSF. Progression of hearing loss is rapid and proceeds from cochlear base to apex in parallel with the degree of inflammation.

Animals↗
PubMed1993

Antiinflammatory effects in experimental meningitis of prokaryotic peptides that mimic selectins.

The lectin domains of two subunits of pertussis toxin, S2 and S3, share amino acid sequence similarity with the lectin domains of the eukaryotic selectin family. During inflammation, selectins appear on endothelial cells and promote recruitment of leukocytes by reversibly binding carbohydrates. Synthetic peptides representing the carbohydrate recognition domains of S2 and S3 competitively inhibited adherence of neutrophils to endothelial cells in vitro. For some peptides, this antiinflammatory effect occurred without up-regulation of the function of the leukocyte integrin CD11b/CD18. Intravenous administration of peptides to animals with meningitis disrupted recruitment of leukocytes into the cerebrospinal fluid. These findings indicate that peptides derived from prokaryotic members of the selectin family have therapeutic antiinflammatory potential.

Amino Acid Sequence↗
PubMed1993

The cell wall mediates pneumococcal attachment to and cytopathology in human endothelial cells.

Streptococcus pneumoniae interacts with vascular endothelial cells during the course of bacteremia. In this study, we characterized the initial attachment of pneumococci to human endothelial cells (EC) and the response of the endothelium to this interaction. Pneumococci adhered to EC in a dose-dependent fashion. Attachment was rapid, with the majority of bacteria attached by 30 min. No difference was found between the attachment of unencapsulated (R6) and encapsulated (SIII) strains. Purified pneumococcal cell wall components competitively inhibited attachment of R6 by a maximum of 60% in a dose-dependent manner. Following attachment of pneumococci or exposure of EC to pneumococcal cell wall, pronounced changes in EC morphology ensued, resulting in striking separation of the cells of the monolayer and, eventually, destruction of the cells. The cytopathic effects of the cell wall were inhibited by antibodies to interleukin-1 but not to tumor necrosis factor. Both antibodies were required to neutralize the cytopathology caused by intact pneumococci. We conclude that pneumococci attach rapidly to human EC and that the cell wall is important in this interaction. Intact pneumococci and pneumococcal cell wall induce profound morphologic changes in human EC, leading to loss of barrier integrity. These cytopathic effects are likely to be cytokine mediated.

Actins↗
PubMed1993

A structure-activity relationship for induction of meningeal inflammation by muramyl peptides.

Components of bacterial peptidoglycans have potent biological activities, including adjuvant effects, cytotoxicity, and induction of sleep. Mixtures of peptidoglycan components also induce inflammation in the lung, subarachnoid space, and joint, but the structural requirements for activity are unknown. Using a rabbit model for meningitis, we determined the biological activities of 14 individual muramyl peptides constituting > 90% of the peptidoglycan of the gram-negative pediatric pathogen Haemophilus influenzae. Upon intracisternal inoculation, most of the muropeptides induced leukocytosis in cerebrospinal fluid (CSF), influx of protein into CSF, or brain edema, alone or in combination. The disaccharide-tetrapeptide, the major component of all gram-negative peptidoglycans, induced CSF leukocytosis and protein influx at doses as low as 0.4 microgram (0.42 nM). Modification of the N-acetyl muramic acid or substitution of the alanine at position four in the peptide side chain decreased leukocytosis but enhanced brain edema. As the size of the muropeptide increased, the inflammatory activity decreased. Muropeptide carrying the diaminopimelyl-diaminopimelic acid cross-link specifically induced cytotoxic brain edema. These findings significantly expand the spectrum of biological activities of natural muramyl peptides and provide the basis for a structure-activity relationship for the inflammatory properties of bacterial muropeptides.

Amino Acid Sequence↗
PubMed1992

Bacterial components and the pathophysiology of injury to the blood-brain barrier: does cell wall add to the effects of endotoxin in gram-negative meningitis?

In animal models, the lipopolysaccharide (LPS) from Haemophilus influenzae contributes to all the signs of meningitis associated with living bacteria. However, when tested in vitro, the amount of LPS in cerebrospinal fluid (CSF) in natural disease shows much greater effects on leukocytes than on endothelial permeability. To investigate whether other bacterial components act with LPS to incite meningeal inflammation, animals were challenged intracisternally with H. influenzae lysates. Upon neutralization of endotoxin, leukocytosis was greatly attenuated, but protein accumulation in CSF persisted. Cell wall from H. influenzae induced meningeal inflammation in a pattern opposite to that of LPS. Its ability to induce blood-brain barrier permeability greatly exceeded its ability to induce leukocytosis in vivo. Thus, cell wall, by acting on endothelia, and LPS, by inducing leukocytosis, may cooperate to induce inflammation in H. influenzae meningitis. Optimal reduction of inflammation and tissue damage in meningitis may require agents directed against cell wall as well as LPS.

Animals↗
PubMed1992

Induction of procoagulant activity on human endothelial cells by Streptococcus pneumoniae.

The inflammatory response in infection caused by gram-negative organisms involves induction of procoagulant activity (PCA) on human endothelial cells. Although infections caused by gram-positive organisms are also associated with fibrin formation and thrombosis, the bacterial determinants inducing PCA are unknown. This study shows that intact pneumococci and the pneumococcal cell wall efficiently induce PCA on human endothelial cells. Upon exposure of endothelial cells to pneumococci, PCA was first detectable at 30 min, peaked at 2 h, and disappeared by 6 h. The specific activities of encapsulated and unencapsulated strains for induction of PCA were equivalent. Purified pneumococcal cell walls were as potent as endotoxin in induction of PCA. The ability to induce a procoagulant state on endothelial cells is a new biological activity of gram-positive cell walls which promotes the participation of the coagulation cascade in the inflammatory response to disease caused by gram-positive organisms.

Blood Coagulation Factors↗
PubMed1992

Differing roles for platelet-activating factor during inflammation of the lung and subarachnoid space. The special case of Streptococcus pneumoniae.

Although well-characterized in the lung, the role of platelet-activating factor (PAF) in inflammation in the central nervous system is undefined. Using rabbit models of meningitis and pneumonia, PAF was found to induce significant blood-brain barrier permeability and brain edema at doses five times lower than those required to generate leukocyte recruitment to the subarachnoid space. Both leukocytosis and increased vascular permeability occurred in response to PAF in the lung. Antibody to the CD-18 family of leukocyte adhesion molecules inhibited leukocyte recruitment in response to PAF in the brain (greater than 80%); a similar level of inhibition in the lung required treatment with a combination of a PAF receptor antagonist (L-659,989) and anti-CD18 antibody. Treatment with L-659,989 decreased abnormal cerebrospinal fluid cytochemical values induced by intracisternal challenge with pneumococci but not Haemophilus influenzae, indicating a special role for PAF in pneumococcal disease. Antibodies directed at phosphorylcholine, a unique, shared determinant of bioactivity of PAF and pneumococcal cell wall, obviated the inflammatory potential of both agents. However, no evidence for a direct PAF-like activity of pneumococcal cell wall components was detected in vitro by bioassay using platelets or neutrophils. It is concluded that PAF can induce inflammation in the subarachnoid space. In brain, PAF effects appear to be mediated through CD-18-dependent events, while in lung, PAF effects independent of CD-18 are also evident. At both sites, PAF is of particular clinical importance during inflammation induced by pneumococci apparently due to a unique proinflammatory relationship between the pneumococcal cell wall teichoic acid and PAF.

Animals↗
PubMed1991

Integrin-mediated localization of Bordetella pertussis within macrophages: role in pulmonary colonization.

The adherence of Bordetella pertussis to human respiratory cilia is critical to the pathogenesis of whooping cough but the significance of bacterial attachment to macrophages has not been determined. Adherence to cilia and macrophages is mediated by two large, nonfimbrial bacterial proteins, filamentous hemagglutinin (FHA), and pertussis toxin (PT). PT and FHA both recognize carbohydrates on cilia and macrophages; FHA also contains an Arg-Gly-Asp (RGD) sequence which promotes bacterial association with the macrophage integrin complement receptor 3 (CR3). We determined that virulent B. pertussis enter and survive in mammalian macrophages in vitro and that CR3 is important for this uptake process. We then determined the relative contribution of CR3 versus carbohydrate-dependent interactions to in vivo pulmonary colonization using a rabbit model. B. pertussis colonized the lung as two approximately equal populations, one extracellular population attached to ciliary and macrophage surface glycoconjugates and another population within pulmonary macrophages. Loss of the CR3 interaction, either by mutation of FHA or treatment with antibody to CR3, disrupted accumulation of viable intracellular bacteria but did not prevent lung pathology. In contrast, elimination of carbohydrate-bound bacteria, either by a competitive receptor analogue or an anti-receptor antibody, was sufficient to prevent pulmonary edema. We propose that CR3-dependent localization of B. pertussis within macrophages promotes persistence of bacteria in the lung without pulmonary injury. On the other hand, the presence of extracellular bacteria adherent to cilia and macrophages in carbohydrate-dependent interactions is associated with pulmonary pathology.

Adhesins, Bacterial↗
PubMed1991

Coordinate regulation of beta-lactamase induction and peptidoglycan composition by the amp operon.

The amp operon, which is located on the Escherichia coli chromosome, modulates the induction of plasmid-borne beta-lactamase genes by extracellular beta-lactam antibiotics. This suggests that the gene products AmpD and AmpE may function in the transduction of external signals. beta-Lactam antibiotics are analogs of cell wall components that can be released during cell wall morphogenesis of enterobacteria. The amp operon was studied to determine its importance in signal transduction during cell wall morphogenesis. The peptidoglycan compositions of amp mutants were determined by high-performance liquid chromatography and fast atom bombardment mass spectrometry. When a chromosomal or plasmid-borne copy of ampD was present, the amount of pentapeptide-containing muropeptides in the cell wall increased upon addition of the cell wall constituent diaminopimelic acid to the growth medium. These results suggest that beta-lactamase induction and modulation of the composition of the cell wall share elements of a regulatory circuit that involves AmpD. Escherichia coli requires AmpD to respond to extracellular signaling amino acids, such as diaminopimelic acid, and this signal transduction system may regulate peptidoglycan composition in response to cell wall turnover products.

Amino Acid Sequence↗
PubMed1991

Hearing loss and pneumococcal meningitis: an animal model.

Clinical studies of predisposing factors in the development of hearing loss secondary to bacterial meningitis have produced conflicting results. An animal model of meningogenic labyrinthitis was developed for more precise study of these parameters. Rabbits were inoculated intrathecally with 10(5) pneumococci to induce meningitis. Hearing thresholds were measured using auditory-evoked responses to 1 kHz, 10 kHz, and click stimuli before infection and every 12 hours thereafter. Profound deafness occurred in all subjects at an average of 48 hours following infection. The incidence and severity of hearing loss was strongly correlated with the duration of meningitis. Temporal bone histology revealed acute inflammation of all perilymphatic spaces including the cochlear aqueduct. This model demonstrated that the risk and severity of hearing loss increase with the duration of meningitis and suggested that the cochlear aqueduct is an anatomic pathway for the extension of infection from the cerebrospinal fluid to the cochlea. The implications for therapy in humans is discussed.

Acoustic Stimulation↗