Extravasation of leukocytes assessed by intravital microscopy: effect of thalidomide

OBJECTIVE AND DESIGN: Thalidomide is very effective in the treatment of idiopathic aphthous stomatitis, characterized by recurrent focal intramucosal leukocytic vasculitis. The mode of action of thalidomide in this clinical entity may include inhibition of the extravasation of leukocytes. Therefore, we studied the effect of thalidomide on different steps of leukocyte migration by intravital microscopy. MATERIAL: Male Syrian golden hamsters were used. TREATMENT: Leukocyte migration in buccal mucosa of the hamster cheek pouch was elicited by the local application of lipopolysaccharide (LPS, 20 micrograms/ml) or murine tumor necrosis factor-alpha (muTNF-alpha, 10 ng/ml). (+)-Thalidomide (20-200 mg/kg i.p.) was administered 60 min before the local application of LPS or muTNF-alpha. Dexamethasone (2 x 1.0-10 mg/kg i.p.) was administered 18 h and 60 min before topical LPS application. METHODS: The numbers of rolling, firmly adherent and migrating leukocytes were estimated by intravital microscopy up to 165 min after the topical applications of LPS or muTNF-alpha and evaluated by an interactive image analysis software. RESULTS: Thalidomide (20-200 mg/kg i.p.) dose-dependently inhibited LPS-stimulated perivenular leukocyte migration by up to 87 +/- 5% and muTNF-alpha-induced leukocyte migration by up to 78 +/- 4%. Dexamethasone (2 x 1.0-10 mg/kg i.p.) inhibited LPS-stimulated leukocyte migration by up to 85 +/- 13%. (+)-Thalidomide (200 mg/kg i.p.) inhibited LPS-stimulated rolling by 80 +/- 5% and reduced the number of firmly adherent leukocytes by about 40%. Dexamethasone (2 x 10 mg/kg i.p.) did not reduce the number of rolling leukocytes but inhibited leukocyte adherence by 72 +/- 9%. CONCLUSIONS: These results show that (+)-thalidomide predominantly inhibits leukocyte rolling and thus differs from the glucocorticoid dexamethasone. The inhibition of LPS- or muTNF-alpha-induced leukocyte extravasation by thalidomide may account for some of its clinical activities.     

Prevalence and correlates of nocturnal desaturations in a sample of elderly people

Rifabutin is a lipophilic antibacterial with high in vitro activity against many pathogens involved in bacterial meningitis including pneumococci. Resistance to beta-lactam antibiotics in pneumococci is not associated with a decreased sensitivity to rifabutin (30 strains from Germany with intermediate penicillin resistance; MIC range of penicillin: 0.125-1 mg/l, MIC of rifabutin: < 0.008-0.015 mg/l). Rifabutin at doses of 0.625, 1.25, 2.5, 5 and 10 mg/kg/h i.v. was investigated in a rabbit model of meningitis using a Streptococcus pneumoniae type 3 (MIC/MBC of rifabutin: 0.015/0.06 mg/l). The bacterial density in CSF at the onset of treatment was 7.3 +/- 0.6 log CFU/ml (mean +/- SD). Rifabutin decreased bacterial CSF titers in a dose-dependent manner [delta log CFU/ml/h (slope of the regression line log CFU/ml vs. time) at a dose of 0.625 mg/kg/h: -0.16 +/- 0.06 (n = 3), at 1.25 mg/kg/h: -0.20 +/- 0.12 (n = 4), at 2.5 mg/kg/h: -0.24 +/- 0.04 (n = 4), at 5 mg/kg/h: -0.31 +/- 0.10 (n = 8), and at 10 mg/kg/h: -0.29 +/- 0.10 (n = 5)]. At high doses rifabutin was as active as ceftriaxone at 10 mg/kg/h (delta log CFU/ml/h: -0.29 +/- 0.10, n = 10). Two and 5 h after initiation of therapy, CSF TNF-alpha activities were lower with rifabutin 5 mg/kg/h than with ceftriaxone (medians 2 vs. 141 U/ml, p = 0.005 at 2 h; median 51 vs. 120 U/ml 5 h after initiation of therapy, p = 0.04). This did not result, however, in a decrease of indicators of neuronal damage. In conclusion, intravenous rifabutin was bactericidal in experimental pneumococcal meningitis. Provided that a well-tolerated i.v. formulation will be available it may qualify as a reserve antibiotic for pneumococcal meningitis, in particular when strains with a reduced sensitivity to beta-lactam antibiotics are the causative pathogens.     

Tumor necrosis factor-alpha induces leukocyte recruitment by different mechanisms in vivo and in vitro

It is well established that E-selectin is the endothelial adhesion molecule that is primarily responsible for mediating leukocyte rolling on TNF-alpha-stimulated cultured endothelial cells. Despite this, few studies in in vivo inflammatory models have observed reduced leukocyte accumulation using mAbs against E-selectin. The objective of this study was to compare the function of E-selectin on endothelial cells in vitro with its role in TNF-alpha-induced leukocyte recruitment in vivo using EL246, a mAb that blocks the function of E-selectin on activated feline endothelial cells. In vitro experiments using feline endothelial cells showed that EL246 functionally inhibits E-selectin-dependent leukocyte recruitment induced by TNF-alpha, without affecting the function of other rolling mechanisms. Intravital microscopy of single 25- to 40-microm venules in the feline mesentery was then used to examine leukocyte rolling and adhesion in response to superfusion with TNF-alpha. TNF-alpha treatment significantly increased the number of both rolling and adherent leukocytes and significantly decreased leukocyte rolling velocity. Treatment with EL246 (1 mg/kg), either i.v. at the start of the TNF-alpha protocol or directly into the superior mesenteric artery after 3 h of TNF-alpha treatment, had no effect on leukocyte rolling, adhesion, or rolling velocity. However, treatment with the selectin-binding carbohydrate, fucoidan, reduced leukocyte rolling to below baseline levels. These results suggest that in contrast to its prominent role on cultured endothelial cells, E-selectin does not contribute to leukocyte recruitment in TNF-alpha-stimulated feline mesenteric venules in vivo.     

Effect of the bradykinin B2 receptor antagonist Hoe140 in experimental pneumococcal meningitis in the rat

To elucidate the role of bradykinin in the complex pathophysiology of bacterial meningitis we investigated the effect of the bradykinin B2 receptor antagonist Hoe140, icatibant (D-Arg[Hyp3-Thi5-D-Tic7-Oic8]-bradykinin), on pathophysiological alterations in experimental pneumococcal meningitis. Untreated rats injected intracisternally (i.c.) with heat-killed pneumococci developed an increase of regional cerebral blood flow (185.4 +/- 27.4%, baseline 100%, mean +/- S.D.), brain water content (79.16 +/- 0.23%), intracranial pressure (21.4 +/- 6.0 mm Hg), and white blood cell count in the cerebrospinal fluid (CSF) (4621 +/- 1894 cells/microliter) within 6 h after i.c. challenge. Treatment with Hoe140 (0.1 mg/kg i.v. at baseline and 0.05 mg/kg s.c. at 2 h after i.c. challenge) attenuated the increase of brain water content (78.53 +/- 0.28%; P < 0.05), intracranial pressure (7.5 +/- 2.2 mm Hg; P < 0.05), and regional cerebral blood flow (128.6 +/- 23.1%; P < 0.05), and reduced CSF pleocytosis (2690 +/- 1898 cells/microliter. N.S.). When treatment was started 4 h after i.c. challenge Hoe140 reduced intracranial pressure (P < 0.05), but was no more capable to significantly influence the other pathophysiological parameters. Treatment with lower (0.01 mg/kg i.v. at baseline, followed by 0.005 mg/kg s.c. at 2 h) and higher (2 mg/kg i.v., followed by 1 mg/kg s.c. at 2 h) concentrations of Hoe140 was ineffective. Likewise, i.c. injection of Hoe140, at different dosages (4 nmol, 40 nmol, 400 nmol) did not significantly alter the pathophysiological parameters in pneumococci-induced meningitis, but caused changes in mean arterial blood pressure at dosages greater than 4 nmol. We conclude that bradykinin is involved as an inflammatory mediator of microvascular changes, brain edema, and increased intracranial pressure during the early phase of experimental pneumococcal meningitis.     

Pharmacokinetics of florfenicol in cerebrospinal fluid and plasma of calves

Florfenicol, a fluorinated analog of thiamphenicol, is of great value in veterinary infectious diseases that formerly responded favorably to chloramphenicol. In view of the treatment of meningitis in calves, we studied its pharmacokinetics in the cerebrospinal fluid (CSF) and plasma of six animals. To this end, a new high-performance liquid chromatography method was developed which, unlike previous ones, uses solid-phase instead of double-phase extraction to isolate the drug. After a single intravenous dose of 20 mg/kg of body weight, a maximum concentration in CSF of 4.67 +/- 1.51 microg/ml (n = 6) was reached, with a mean residence time of 8.7 h. The decline of florfenicol in both CSF and plasma fitted a biexponential model with elimination half-lives of 13.4 and 3.2 h, respectively. Florfenicol penetrated well into CSF, as evidenced from an availability of 46% +/- 3% relative to plasma. The levels remained above the MIC for Haemophilus somnus over a 20-h period. Our results provide evidence indicating the effectiveness of florfenicol in the treatment of bacterial meningitis of calves.     

Moxifloxacin in the therapy of experimental pneumococcal meningitis

The activity of moxifloxacin (BAY 12-8039) against a Streptococcus pneumoniae type 3 strain (MIC and minimum bactericidal concentration [MBC] of moxifloxacin, 0.06 and 0.25 microgram/ml, respectively; MIC and MBC of ceftriaxone, 0.03 and 0.06 microgram/ml, respectively) was determined in vitro and in a rabbit model of meningitis. Despite comparable bactericidal activity, 10 micrograms of moxifloxacin per ml released lipoteichoic and teichoic acids less rapidly than 10 micrograms of ceftriaxone per ml in vitro. Against experimental meningitis, 10 mg of moxifloxacin per kg of body weight per ml reduced the bacterial titers in cerebrospinal fluid (CSF) almost as rapidly as ceftriaxone did (mean +/- standard deviation, -0.32 +/- 0.14 versus -0.39 +/- 0.11 delta log CFU/ml/h). The activity of moxifloxacin could be described by a sigmoid dose-response curve with a maximum effect of -0.33 delta log CFU/ml/h and with a dosage of 1.4 mg/kg/h producing a half-maximal effect. Maximum tumor necrosis factor activity in CSF was observed later with moxifloxacin than with ceftriaxone (5 versus 2 h after the initiation of treatment). At 10 mg/kg/h, the concentrations of moxifloxacin in CSF were 3.8 +/- 1.2 micrograms/ml. Adjunctive treatment with dexamethasone at 1 mg/kg prior to the initiation of antibiotic treatment only marginally reduced the concentrations of moxifloxacin in CSF (3.3 +/- 0.6 micrograms/ml). In conclusion, moxifloxacin may qualify for use in the treatment of S. pneumoniae meningitis.     

Heparin inhibits leukocyte rolling in pial vessels and attenuates inflammatory changes in a rat model of experimental bacterial meningitis

Heparin is a natural proteoglycan that was first described in 1916. In addition to its well characterized effect on blood coagulation, it is becoming clear that heparin also modulates inflammatory processes on several levels, including the interference with leukocyte-endothelium interaction. Anecdotal observations suggest a better clinical outcome of heparin-treated patients with bacterial meningitis. The authors demonstrate that heparin, a glycosaminoglycan, inhibits significantly in the early phase of experimental pneumococcal meningitis the increase of 1) regional cerebral blood flow (125 +/- 18 versus 247 +/- 42%), 2) intracranial pressure (4.5 +/- 2.0 versus 12.1 +/- 2.2 mm Hg), 3) brain edema (brain water content: 78.23 +/- 0.33 versus 79.49 +/- 0.46%), and 4) influx of leukocytes (571 +/- 397 versus 2400 +/- 875 cells/microL) to the cerebrospinal fluid compared with untreated rats. To elucidate the possible mechanism of this observation, the authors investigated for the first time leukocyte rolling in an inflammatory model in brain venules by confocal laser scanning microscopy in vivo. Heparin significantly attenuates leukocyte rolling at 2, 3, and 4 hours (2.8 +/- 1.3 versus 7.9 +/- 3.2/100 microm/min), as well as leukocyte sticking at 4 hours (2.1 +/- 0.4 versus 3.5 +/- 1.0/100 microm/min) after meningitis induction compared with untreated animals. The authors conclude that heparin can modulate acute central nervous system inflammation and, in particular, leukocyte-endothelium interaction, a key process in the cascade of injury in bacterial meningitis. They propose to evaluate further the potential of heparin in central nervous system inflammation in basic and clinical studies.     

Cellular and molecular mechanisms of metastasis as applied to carcinomatous meningitis

Cancer cells as well as bacteria metastasize to the subarachnoidal space (SAS) causing meningitis. Primary brain tumors, although not forming distant metastases, disseminate via the cerebrospinal fluid and occupy the meninges. The multistep process of cancer or bacterial dissemination is regulated through molecular crosstalk between invaders and host cells. Such crosstalks establish invasion-promoter and invasion-suppressor complexes. In carcinomatous and bacterial meningitis, the participation of host cells is prominent since leukocytes and inflammatory cytokines are the major determinants of malignancy. We propose a model in which bacterial breakdown products activate endothelial cells, a process leading to leukocyte extravasation. This initiates a cascade of inflammatory processes opening up the blood cerebrospinal fluid barrier and producing access for new invaders.     

The value of C-reactive protein for the differentiation of bacterial meningitis from viral meningitis

In order to differentiate bacterial meningitis versus viral meningitis, we have comparatively tested the efficacy of the following tests: C-reactive protein (CRP), erythrocytes sedimentation rate (ESR), fever, level of glucose in cerebro-spinal fluid (CSF), glucose in CSF/glycemia ratio, number of white blood cells in peripheric blood, percentage of neutrophils in peripheric blood, level of proteins in CSF and number of nucleated cells in CSF for a group of 49 patients, both children and adults with central nervous system infection (37 patients with bacterial meningitis and 12 with viral meningitis) hospitalised between May 1993 and July 1994 in Clinical Hospital for Infectious Diseases in Ia?i. The mean value of CRP in bacterial meningitis patients was 8.78 mg%, contrasting with the mean value of CRP = 1.92 mg% recorded in patients with viral meningitis. Ten out of 37 bacterial meningitis patients presented a CRP concentration < 1.85 mg%. All these 10 patients have already had an antibiotic treatment at the moment of the assay. One out of 12 cases of viral meningitis had a value of CRP = 3.3 mg%, all the remainder cases having values under 1.85 mg%. We recorded highly significant differences between the two patient groups for CRP (p < 0.001), ESR (p < 0.01), protein concentration in CSF (p < 0.001) and number of nucleated cells in CSF (p < 0.001). Differences recorded for fever, concentration of glucose in CSF, glucose in CSF/glycemia ratio, number of leucocytes in peripheric blood and percentage of neutrophils in peripheric blood, were not significant (p > 0.5). Data were analysed also by box-plot method which facilitates the visual appraisal of the differences recorded between the two aetiological groups. In conclusion, assays of CRP and ESR may be used as differentiation tests for bacterial meningitis versus viral meningitis, when assay is done before the antibiotic treatment, being sufficient sensitive, and easy to perform.     

Stability over time of serum antibody levels to human papillomavirus type 16

Protein concentration, leukocyte density, and lactate concentration were studied in 41 pairs of ventricular and lumbar CSF drawn at an interval of less than 24 hours from patients with suspected bacterial CNS infections. The ventriculo-lumbar ratios ranged from 0.003 to 10.2 (median=0.42) for protein and from 0.002 to 53.5 (median=0.17) for leukocytes. The uneven distribution of leukocytes and proteins in the CSF space may produce findings that fail to indicate bacterial CNS infections. Lactate was distributed more homogeneously in the CSF space than protein and leukocytes (ventriculo-lumbar ratio 0.52 to 1.66 [median=0.811).     

Basic fibroblast growth factor in experimental and clinical bacterial meningitis

Basic fibroblast growth factor (bFGF), a neurotrophic factor in the CNS, is expressed at high levels in response to seizures or strokes. We examined the expression of bFGF during experimental bacterial meningitis and the levels of bFGF in the cerebrospinal fluid (CSF) of children with bacterial meningitis. For the experimental study, a mouse model of meningitis was established by intracranial injection of Streptococcus pneumoniae. Twenty-four hours after induced meningitis, the brains were sectioned and stained immunohistochemically for bFGF. Neutrophils and macrophages infiltrating the leptomeninges and the ventricles exhibited strong bFGF immunoreactivity. The neurons in the areas adjacent to the inflamed ventricles also showed enhanced bFGF expression. For the clinical study, we used an enzyme immunoassay to measure bFGF in CSF in 18 children with bacterial meningitis, 12 with aseptic meningitis, and 18 controls. The CSF levels of bFGF were twice as high in children with bacterial meningitis (medians 6.75-7.21 pg/mL) compared with those who had aseptic meningitis (2.9 pg/mL) or in control subjects (2.65 pg/mL, p < 0.0001, respectively). In patients with bacterial meningitis who survived, CSF bFGF decreased significantly after 24-50 h of antibiotic therapy (p < 0.0005). Patients who developed major sequelae or died had much higher levels of CSF bFGF than those without (134.9 pg/mL versus 7.38 pg/mL, p < 0.05). These findings of enhanced immunoreactivity of bFGF in experimental bacterial meningitis and an association of CSF levels of bFGF with disease severity in childhood bacterial meningitis suggest a biologic role for this neurotrophic factor in the pathophysiology of bacterial meningitis.     

Oxidized LDL-induced leukocyte/endothelium interaction in vivo involves the receptor for platelet-activating factor

Leukocyte adhesion and subendothelial emigration, constant hallmarks of early atherogenesis, have been ascribed to the action of oxidized low-density lipoprotein (oxLDL). Using intravital fluorescence microscopy in the skinfold-chamber model in hamsters, we have previously shown that systemic administration of oxLDL stimulates leukocyte adhesion in vivo through a mechanism that depends on the generation and/or action of both leukotrienes and superoxide radicals. On the basis of the fact that oxygen radical-catalyzed peroxidation of phospholipids results in the generation of fragments with short sn2 residues, which besides authentic platelet-activating factor (PAF), activate the receptor for PAF on leukocytes and thereby induce leukocyte adhesion, we asked whether pretreatment of hamsters with a specific PAF receptor antagonist (WEB2170; 1 mg/kg of body weight IV, 10 minutes before oxLDL) attenuates leukocyte adhesion after injection of oxLDL (4 mg/kg of body weight IV, oxidized by 7.5 mumol/L Cu2+ for 18 hours at 37 degrees C). We demonstrate herein that in contrast to untreated control animals in which oxLDL elicited rolling and adhesion of circulating leukocytes to the endothelium of venules and arterioles, oxLDL-induced leukocyte adhesion was significantly attenuated in WEB2170-pretreated animals. These changes cannot be ascribed to alterations of microhemodynamic parameters and, hence, wall shear conditions. This finding indicates that oxLDL-induced leukocyte/endothelium interaction involves the PAF receptor, which may function both as a receptor for authentic PAF or for PAF-like lipids that are generated in a free radical-catalyzed peroxidation of phospholipids.     

Reduction of central nervous system reperfusion injury in rabbits using doxycycline treatment

BACKGROUND AND PURPOSE: Activated leukocytes appear to potentiate central nervous system reperfusion injury, and agents that block leukocyte adhesion have shown neuroprotective efficacy in experimental models. Doxycycline, a tetracycline antibiotic, inhibits leukocyte function in vitro, presumably through divalent cation binding. We used a model of focal central nervous system reperfusion injury to determine the efficacy of doxycycline treatment in preserving neurological function. METHODS: Rabbits randomly received 10 mg/kg i.v. doxycycline 30 minutes before ischemia (pretreatment group) or 45 minutes after ischemia (posttreatment group) or received phosphate-buffered saline vehicle (control group) followed by 10 mg/kg q 8 hours times two. The average length of reversible spinal cord ischemia required to produce paraplegia (P50) at 18 hours was calculated for each group. RESULTS: For the control group (n = 13), the P50 was 22.8 +/- 2.2 minutes; for the pretreatment group (n = 14), 35.5 +/- 2.4 minutes (P < .01; t = 3.8); and for the posttreatment group (n = 13), 31.4 +/- 4.2 minutes (not significant; t = 1.6). Doxycycline also attenuated postischemic decreases in vivo leukocyte counts and inhibited in vitro leukocyte adhesion. Therapeutic doxycycline levels at 24 hours were confirmed in the plasma and spinal cord. CONCLUSIONS: This significant protective effect suggests that doxycycline, a safe and readily available agent, may play a role in reducing clinical central nervous system reperfusion injury.     

Disposition and elimination of meropenem in cerebrospinal fluid of hydrocephalic patients with external ventriculostomy

The broad antibacterial spectrum and the low incidence of seizures in meropenem-treated patients qualifies meropenem for therapy of bacterial meningitis. The present study evaluates concentrations in ventricular cerebrospinal fluid (CSF) in the absence of pronounced meningeal inflammation. Patients with occlusive hydrocephalus caused by cerebrovascular diseases, who had undergone external ventriculostomy (n = 10, age range 48 to 75 years), received 2 g of meropenem intravenously over 30 min. Serum and CSF were drawn repeatedly and analyzed by liquid chromatography-mass spectroscopy. Pharmacokinetics were determined by noncompartmental analysis. Maximum concentrations in serum were 84.7 +/- 23.7 microg/ml. A CSF maximum (CmaxCSF) of 0.63 +/- 0.50 microg/ml (mean +/- standard deviation) was observed 4.1 +/- 2.6 h after the end of the infusion. CmaxCSF and the area under the curve for CSF (AUCCSF) depended on the AUC for serum (AUCS), the CSF-to-serum albumin ratio, and the CSF leukocyte count. Elimination from CSF was considerably slower than from serum (half-life at beta phase [t1/2beta] of 7.36 +/- 2.89 h in CSF versus t1/2beta of 1.69 +/- 0.60 h in serum). The AUCCSF/AUCS ratio for meropenem, as a measure of overall CSF penetration, was 0.047 +/- 0.022. The AUCCSF/AUCS ratio for meropenem was similar to that for other beta-lactam antibiotics with a low binding to serum proteins. The concentration maxima of meropenem in ventricular CSF observed in this study are high enough to kill fully susceptible pathogens. They may not be sufficient to kill bacteria with a reduced sensitivity to carbapenems, although clinical success has been reported for patients with meningitis caused by penicillin-resistant pneumococci and Pseudomonas aeruginosa.     

Pharmacokinetic profiles of ceftazidime in cochlear perilymph, cerebrospinal fluid and plasma: a high-performance liquid chromatographic study

A pharmacokinetic profile of the antibiotic ceftazidime was established for perilymph, cerbrospinal fluid (CSF) and plasma in 12 guinea pigs using the technique of high-performance liquid chromatography. The mean peak levels of 13.35 mg/l in perilymph and 140.54 mg/l in plasma were reached within the first hour after a single intravenous dose of 100 mg/kg. The CSF mean peak level of 5.36 mg/l, however, was not attained until 3 h after injection. The half-life was about 4 h in perilymph, more than 6 h in CSF and less than 2 h in plasma. Six hours following administration, the perilymph drug concentration remained higher than the plasma level. The study indicates that ceftazidime has excellent penetration into perilymph. It is concluded that ceftazidime should be a very useful agent in the treatment of bacterial labyrinthitis caused by susceptible organisms.     

Pharmacokinetic optimisation of the treatment of bacterial central nervous system infections

Central nervous system (CNS) infections caused by bacteria with reduced sensitivity to antibacterials are an increasing worldwide challenge. In successfully treating these infections the following conditions should be considered: (i) Antibacterials do not distribute homogeneously in the central nervous compartments [cerebrospinal fluid (CSF), extracellular space of the nervous tissue, intracellular space of the neurons, glial cells and leucocytes]. Even within the CSF, after intravenous administration, a ventriculo-lumbar concentration gradient is often observed. (ii) Valid parameters of drug entry into the CSF are the CSF: serum concentration ratio in steady state and the CSF: serum ratio of the area under the concentration-time curves (AUCCSF/AUCS). Frequently, the elimination half-life (t1/2 beta) in CSF is longer than t1/2 beta in serum. (iii) For most antibacterials, lipophilicity, molecular weight and serum protein binding determine the drug entry into the CSF and brain tissue. With an intact blood-CSF and blood-brain barrier, the entry of hydrophilic antibacterials (beta-lactam antibacterials, glycopeptides) into the CNS compartments is poor and increases during meningeal inflammation. More lipophilic compounds [metronidazole, quinolones, rifampicin (rifampin) and chloramphenicol] are less dependent on the function of the blood-CSF and blood-brain barrier. (iv) Determination of the minimal inhibitory concentrations (MIC) of the causative organism is necessary for optimisation of treatment. (v) For rapid sterilisation of CSF, drug concentrations of at least 10 times MIC are required. The minimum CSF concentration: MIC ratio ensuring successful therapy is unknown. Strategies to achieve optimum antibacterial concentrations in the presence of minor disturbances of the blood-CSF and blood-brain barrier include, the increased use of low toxicity antibacterials (e.g., beta-lactam antibiotics), the use of moderately lipophilic compounds, and the combination of intravenous and intraventricular administration. Antibacterials which do not interfere with bacterial cell wall synthesis delay and/or decrease the liberation of proinflammatory bacterial products, delay or inhibit tumour necrosis factor release, and may reduce brain oedema in experimental meningitis. Conclusive evidence of the reduction of neuronal damage by this approach, however, is lacking.     

Impact of deltamethrin impregnated mosquito nets on the transmission of malaria in the coastal lagoon area, Benin]

Neopterin has been determined in blood as a marker of cellular immune system activation. We studied cerebrospinal fluid (CSF) neopterin levels in children with neurologic diseases, and the following results were obtained: (1) CSF neopterin levels markedly increased at the acute phase of bacterial meningitis, aseptic meningitis, and encephalitis as compared with those in patients without neurologic diseased. (2) In the CSF of patients with bacterial meningitis and aseptic meningitis, neopterin levels decreased more rapidly than the total cell count and 2'5' oligoadenylate synthetase (2-5 AS) did. (3) CSF neopterin in patients with non-infectious neurologic diseases was almost equal to that in patients without neurologic diseases. (4) There was no correlation between CSF neopterin and other CSF values, such as total cell count, mononuclear cell count, protein, and 2-5 AS. These results suggest that CSF neopterin is a useful marker of inflammatory central nervous diseases.     

Pharmacokinetics of enrofloxacin after intravenous, intramuscular and oral administration in houbara bustard (Chlamydotis undulata macqueenii)

The in-vitro activity of enrofloxacin against 117 strains of bacteria isolated from bustards was determined. Minimum inhibitory concentrations for 72% of the Proteus spp., E. coli, Salmonella spp. and Klebsiella spp. (n = 61) and for 48% of the Streptococci spp. and Staphylococci spp. (n = 31) were < or = 0.5 microg/mL. The minimum inhibitory concentration (MIC) of 76% of Pseudomonas spp. (n = 25) was < or = 2 microg/mL. Fourteen strains were resistant to concentrations > or = 128 microg/mL. The elimination half-lives (t1/2 elim beta) (mean +/- SEM) of 10 mg/kg enrofloxacin in eight houbara bustards (Chlamydotis undulata) were 6.80 +/- 0.79, 6.39 +/- 1.49 and 5.63 +/- 0.54 h after oral (p.o.), intramuscular (i.m.) and intravenous (i.v.) administration, respectively. Enrofloxacin was rapidly absorbed from the bustard gastro-intestinal tract and maximum plasma concentrations of 1.84 +/- 0.16 microg/mL were achieved after 0.66 +/- 0.05 h. Maximum plasma concentration after i.m. administration of 10 mg/kg was 2.75 +/- 0.11 microg/mL at 1.72 +/- 0.19 h. Maximum plasma concentration after i.m. administration of 15 mg/kg in two birds was 4.86 microg/mL. Bioavailability was 97.3 +/- 13.7% and 62.7 +/- 11.1% after i.m. and oral administration, respectively. Plasma concentrations of enrofloxacin > or = 0.5 microg/mL were maintained for at least 12 h for all routes at 10 mg/kg and for 24 h after i.m. administration at 15 mg/kg. Plasma enrofloxacin concentrations were monitored during the first 3 days of treatment in five houbara bustards and kori bustards (Ardeotis kori) with bacterial infections receiving a single daily i.m. injection of 10 mg/kg for 3 days. The mean plasma enrofloxacin concentrations in the clinical cases at 27 and 51 h (3.69 and 3.86 microg/mL) and at 48 h (0.70 microg/mL) were significantly higher compared with the 3 h and 24 h time intervals from clinically normal birds. The maximum plasma concentration (Cmax)/MIC ratio was ranked i.v. (10/mg/kg) > i.m. (15 mg/kg) > i.m. (10 mg/kg) > oral (10 mg/kg), but it was only higher than 8:1 for i.v. and i.m. administrations of enrofloxacin at 10 mg/kg and 15 mg/kg, respectively, against a low MIC (0.5 microg/mL). A dosage regimen of 10 mg/kg repeated every 12 h, or 15 mg/kg repeated every 24 h, would be expected to give blood concentrations above 0. 5 microg/mL and hence provide therapeutic response in the bustard against a wide range of bacterial infections.     

Quinolone antibiotics in therapy of experimental pneumococcal meningitis in rabbits

Using a rabbit model of pneumococcal meningitis, we compared the pharmacokinetics and bactericidal activities in cerebrospinal fluid (CSF) of older (ciprofloxacin, ofloxacin) and newer (levofloxacin, temafloxacin, CP-116,517, and Win 57273) quinolones with those of the beta-lactam ceftriaxone. All quinolones penetrated into the inflamed CSF better than ceftriaxone, and the speed of entry into CSF was closely related to their degrees of lipophilicity. At a dose of 10 mg/kg.h, which in the case of the quinolones already in use in clinical practice produced concentrations attainable in the sera and CSF of humans, ciprofloxacin had no antipneumococcal activity (delta log10 CFU/ml.h, +0.20 +/- 0.14). Ofloxacin (delta log10 CFU/ml.h, -0.13 +/- 0.12), temafloxacin (delta log10 CFU/ml.h, -0.19 +/- 0.18), and levofloxacin (delta log10 CFU/ml.h, -0.24 +/- 0.16) showed slow bactericidal activity (not significantly different from each other), while CP-116,517 (delta log10 CFU/ml.h, -0.59 +/- 0.21) and Win 57273 (delta log10 CFU/ml.h, -0.72 +/- 0.20) showed increased bactericidal activities in CSF that was comparable to that of ceftriaxone at 10 mg/kg.h (delta log10 CFU/ml.h, -0.80 +/- 0.17). These improved in vivo activities of the newer quinolones reflected their increased in vitro activities. All quinolones and ceftriaxone showed positive correlations between bactericidal rates in CSF and concentrations in CSF relative to their MBCs. Only when this ratio exceeded 10 did the antibiotics exhibit rapid bactericidal activities in CSF. In conclusion, in experimental pneumococcal meningitis the activities of new quinolones with improved antipneumococcal activities were comparable to that of ceftriaxone.     

Vancomycin cerebrospinal fluid concentrations after intravenous administration in premature infants

OBJECTIVE: Staphylococcal species are the most common cause of nosocomial infections in the neonate. Because of staphylococcal resistance patterns, vancomycin has become the drug of choice for treatment. Although the blood stream is the usual site of infection, premature infants are at increased risk for the development of meningitis. The aim of this study was to determine vancomycin cerebrospinal fluid (CSF) concentration and penetration following intravenous (IV) administration in critically ill premature infants. STUDY DESIGN: A multiple-dose, open-label, case series was performed at a level III neonatal intensive care unit in a university teaching hospital. Three critically ill premature infants, 26 to 31 weeks of gestation requiring a course of IV vancomycin for suspected or proved sepsis were studied. Vancomycin was administered intravenously at 20 mg/kg, every 18 to 24 hours over 60 minutes. Serum and CSF vancomycin concentrations were obtained and pharmacokinetic analysis and CSF penetration was calculated. RESULTS: Serum vancomycin pharmacokinetics were consistent with those previously reported. CSF vancomycin concentrations ranged from 2.2 to 5.6 micrograms/ml and the calculated vancomycin CSF penetration ranged from 26% to 68%. CONCLUSIONS: CSF penetration of vancomycin after IV administration was much higher than that reported in older infants and children. This higher penetration may improve clinical outcomes in neonates with central nervous system infections. These data should be encouraging to clinicians who choose to use IV vancomycin for neonatal meningitis.