Vbeta-restricted T cell adherence to endothelial cells: a mechanism for superantigen-dependent vascular injury

OBJECTIVE

To investigate the potential for endothelial cells to operate as superantigen-presenting cells for T cells and the potential for such an interaction to cause endothelial cell activation and injury.

METHODS

Class II major histocompatibility complex (MHC)-positive human umbilical vein endothelial cells (HUVECs) were cocultured for 4 hours with purified T cells and the superantigens staphylococcal enterotoxin B (SEB) or toxic shock syndrome toxin 1 (TSST-1). After staining with fluorescence-conjugated monoclonal antibodies, flow cytometric analysis was performed on the HUVECs and T cells to examine V(beta)-restricted T cell adherence to the endothelial cell monolayer, V(beta)-restricted T cell activation (CD69 up-regulation), surface expression of endothelial cell activation markers, and generation of endothelial microparticles (EMPs).

RESULTS

Coculture of purified T cells with class II MHC-positive HUVECs and either TSST-1 or SEB resulted in V(beta)-restricted CD69 up-regulation by CD4 and CD8 cells (V(beta)2 activation for TSST-1; V(beta)3, V(beta)5.1, and V(beta)12 activation for SEB). Additionally, there was CD4 and CD8 T cell V(beta)-restricted adherence to the HUVEC monolayer at 4 hours. Expression of intercellular adhesion molecule 1, E-selectin, and vascular cell adhesion molecule 1 was up-regulated on the class II MHC-positive HUVECs following exposure to superantigen in the presence of T cells, and there was increased EMP release from activated HUVECs, which occurred earlier and was of greater magnitude than that observed in response to tumor necrosis factor alpha.

CONCLUSION

Class II MHC-positive endothelial cells operate as competent superantigen-presenting cells for CD4 and CD8 lymphocytes in vitro. Dual signaling between endothelial cells and T cells results in V(beta)-restricted activation and adherence to endothelial monolayers and endothelial cell activation and release of EMPs expressing inducible cell adhesion molecules. It is proposed that this mechanism could account in part for the vascular injury associated with superantigen-mediated diseases including Kawasaki disease.

Circulating aldosterone levels are unexpectedly low in children with acute meningococcal disease

The incidence of meningococcal disease in childhood has risen over the past decade. Mortality remains high for those who develop septic shock and purpura fulminans. Poor perfusion, hypotension, and loss of intravascular circulating volume may be expected to influence both mineralocorticoid and glucocorticoid secretion. The aim of the study was to define adrenocortical hormone status at presentation. Sixty children admitted to the pediatric intensive care unit were studied. Children were divided into two groups: group A (n = 31), with meningococcal sepsis, mean age 4.4 yr (range 0.5-14.4), predicted risk of mortality mean 32.3% (range 0.5-99.3%); and group B (n = 29), with other diagnoses (post major surgery and with severe respiratory infections), mean age 4.1 yr (range 0.3-16.3), predicted risk of mortality mean 9.4% (range 0.2-83%). The groups were not significantly different for age. Plasma levels of aldosterone and cortisol were determined by RIA. The mean plasma aldosterone concentration on admission in group A was 427.5 +/- 88.1 pg/ml, with 96.7% of values within the normal range for age for healthy children and were significantly lower than group B mean, 1489.2 +/- 244.2 pg/ml (P < 0.0001), with 59.3% of values above the normal range. In group A there was no correlation with plasma concentrations of sodium, potassium, or volume of colloid infused in the previous 8 h. In group A mean serum cortisol mean values were 799.5 +/- 75.9 nmol/liter and in group B cortisol levels were 703.4 +/- 78.6 nmol/liter (P = n.s.). We conclude that children with meningococcal disease present with lower plasma aldosterone concentrations than other patients in the pediatric intensive care unit, for which there is no clear explanation. Further work is needed to elucidate the mechanisms underlying this finding and to examine its clinical implications.

Circulating aldosterone levels are unexpectedly low in children with acute meningococcal disease

The incidence of meningococcal disease in childhood has risen over the past decade. Mortality remains high for those who develop septic shock and purpura fulminans. Poor perfusion, hypotension, and loss of intravascular circulating volume may be expected to influence both mineralocorticoid and glucocorticoid secretion. The aim of the study was to define adrenocortical hormone status at presentation. Sixty children admitted to the pediatric intensive care unit were studied. Children were divided into two groups: group A (n = 31), with meningococcal sepsis, mean age 4.4 yr (range 0.5-14.4), predicted risk of mortality mean 32.3% (range 0.5-99.3%); and group B (n = 29), with other diagnoses (post major surgery and with severe respiratory infections), mean age 4.1 yr (range 0.3-16.3), predicted risk of mortality mean 9.4% (range 0.2-83%). The groups were not significantly different for age. Plasma levels of aldosterone and cortisol were determined by RIA. The mean plasma aldosterone concentration on admission in group A was 427.5 +/- 88.1 pg/ml, with 96.7% of values within the normal range for age for healthy children and were significantly lower than group B mean, 1489.2 +/- 244.2 pg/ml (P < 0.0001), with 59.3% of values above the normal range. In group A there was no correlation with plasma concentrations of sodium, potassium, or volume of colloid infused in the previous 8 h. In group A mean serum cortisol mean values were 799.5 +/- 75.9 nmol/liter and in group B cortisol levels were 703.4 +/- 78.6 nmol/liter (P = n.s.). We conclude that children with meningococcal disease present with lower plasma aldosterone concentrations than other patients in the pediatric intensive care unit, for which there is no clear explanation. Further work is needed to elucidate the mechanisms underlying this finding and to examine its clinical implications.

Value of negative spiral CT angiography in patients with suspected acute PE: analysis of PE occurrence and outcome

The aim of this study was to analyze pulmonary embolism (PE) occurrence and retrospective clinical outcome in patients with clinically suspected acute PE and a negative spiral CT angiography (SCTA) of the pulmonary arteries. Within a 35-month period, 485 consecutive patients with clinical symptoms of acute PE underwent SCTA of the pulmonary arteries. Patients with a negative SCTA and without anticoagulation treatment were followed-up and formed the study group. Patient outcome and recurrence of PE was evaluated retrospectively during a period of 6 months after the initial SCTA, and included a review of computerized patient records, and interviews with physicians and patients. Patients were asked to fill out a questionnaire concerning all relevant questions about their medical history and clinical course during the follow-up period. Special attention was focused on symptoms indicating recurrent PE, as well as later confirmation and therapy of PE. Of the 485 patients, 325 patients (67%) had a negative scan, 134 (27.6%) had radiological signs of PE, and 26 (5.4%) had an indeterminant result. Of 325 patients with a negative scan, 269 (83%) were available for follow-up. The main reasons for loss to follow-up were change of address, name, or phone number, or non-resident patients who left abroad. Of 269 patients available for follow-up, 49 patients (18.2% of 269) received anticoagulant treatment because of prior or recent deep venous thrombosis (32.6%) or a history of PE (34.7%), cardiovascular disease (18.4%), high clinical probability (8.2%), positive ventilation-perfusion scan (4.2%), and elevated D-dimer test (2%). The remaining 220 patients, who did not receive anticoagulant medication, formed the study group. Of this study group, 1 patient died from myocardial infarction 6 weeks after the initial SCTA, and the postmortem examination also detected multiple peripheral emboli in both lungs ( p=0.45%; 0.01-2.5, 95% confidence interval). The PE did not occur in any other patient. In patients with suspected PE and negative SCTA without anticoagulant therapy, the risk of recurrent PE in this study was less than 1% and similar to that in patients after a negative pulmonary angiogram. Therefore, we conclude that patients can be managed safely without anticoagulation therapy; however, this approach may not be appropriate for critically ill patients and those with persistent high clinical suspicion of acute PE.

Endothelial and platelet microparticles in vasculitis of the young

OBJECTIVE

Microparticles are released from endothelial cells in response to a variety of injurious stimuli and recently have been shown to be increased in a number of diseases associated with endothelial dysfunction. This study examined endothelial microparticle (EMP) and platelet microparticle (PMP) profiles in children with systemic vasculitis to test the hypothesis that EMPs may provide a noninvasive means of examining endothelial activation or injury.

METHODS

The study cohort comprised 39 children with systemic vasculitis at various stages of disease activity, 24 control children with febrile disease, and a control group of 43 healthy subjects. Plasma was ultracentrifuged at 17,000g for 60 minutes, and the microparticle pellets were examined using flow cytometry.

RESULTS

Plasma from patients with active systemic vasculitis contained significantly higher numbers of E-selectin-positive EMPs compared with that from patients in remission, healthy controls, or febrile disease controls (P = 0.000 for each). A similar result was obtained for the numbers of EMPs expressing the marker CD105. There was also a significant increase in PMPs expressing CD42a in the active vasculitis group as compared with the other groups, but this difference was not significant for PMPs expressing P-selectin. The EMP counts correlated with the Birmingham Vasculitis Activity Score and the acute-phase reactant levels in the patients with systemic vasculitis, but there was a poor correlation overall between EMP counts and the acute-phase reactant levels in the febrile disease controls.

CONCLUSION

EMPs may provide a window to the activated endothelium and could provide important pathophysiologic insights into the vascular injury associated with vasculitis of the young.

Growth hormone enhances proinflammatory cytokine production by monocytes in whole blood

Growth hormone (GH) has been used as anabolic therapy to treat catabolic patients. In a recent study, however, administration of high doses of GH to critically ill adults was associated with an increase in morbidity and mortality. Preponderance of septic shock and uncontrolled infections as causes of death in these patients suggests an immuno-modulatory effect of GH. Our hypothesis was that GH treatment may modulate the production of proinflammatory cytokines, which are implicated in sepsis. In our study, human monocytes in whole blood were activated with lipopolysaccaharide (LPS) (1-100 ng/ml) purified from a clinical isolate of group B Neisseria meningitidis in the presence of a high dose of GH (100 ng/ml). The subsequent proinflammatory cytokine response was analysed by intracellular cytokine staining and flow cytometry. Our results show that GH enhances IL1-alpha, IL-6 and TNF-alpha production by LPS activated monocytes in whole blood. The modulation of cytokines by GH may be responsible for the adverse consequences of GH in critically ill patients.

Anomalous coherence peak in the microwave conductivity of c-axis oriented MgB2 thin films

The temperature dependence of the real part of the microwave complex conductivity at 17.9 GHz obtained from surface impedance measurements of two c-axis oriented MgB2 thin films reveals a pronounced maximum at a temperature around 0.6 times the critical temperature. Calculations in the frame of a two-band model based on Bardeen-Cooper-Schrieffer (BCS) theory suggest that this maximum corresponds to an anomalous coherence peak resembling the two-gap nature of MgB2. Our model assumes there is no interband impurity scattering and a weak interband pairing interaction, as suggested by band structure calculations. In addition, the observation of a coherence peak indicates that the pi band is in the dirty limit and dominates the total conductivity of our films.

T cell Vbeta repertoires in childhood vasculitides

Superantigens (SAgs) are potent stimulators of T cells bearing specific Vbeta T cell receptors (TCR) and may play a role in the aetiopathogenesis of systemic vasculitis, although this remains contentious. To investigate the possible aetiological role of SAgs, this study examined peripheral blood T cell Vbeta repertoires in children with systemic vasculitis. FACS analysis of 17 different peripheral blood T cell Vbeta families was performed in 20 healthy control children, 27 disease control children with nonvasculitic inflammatory disease, 25 children with primary systemic vasculitis, six patients with Kawasaki disease (KD) and six patients with Henoch-Schönlein purpura (HSP). There was a significantly increased variance of CD4 Vbeta12 and Vbeta17, and CD8 Vbeta1 in the primary systemic vasculitis group compared to control and disease controls. Moreover, 80% of the primary systemic vasculitis children had one or more CD4 Vbeta expansions or deletions, compared with 30% of controls (P < 0.002), and 37% of the disease controls (P < 0.002). In the KD group, the mean percentage of CD4 Vbeta2 T cells was higher than in controls or disease controls. In the HSP group, there was no consistent skewing of the T cell Vbeta repertoire. We have observed changes in the T cell Vbeta repertoire in children with vasculitis over and above those observed in disease controls. While these data provide impetus for further research into this contentious field, they do not resolve unequivocally the question of the role of SAgs in childhood vasculitic syndromes.

Transcapillary insulin transfer in human skeletal muscle

BACKGROUND

Transcapillary insulin transfer is considered a rate-limiting step in insulin action at supraphysiological insulin concentrations. However, it remains unclear whether this concept also applies for physiological conditions.

MATERIALS AND METHODS

In the present study we set out to characterize transcapillary insulin transfer by measuring insulin concentrations in plasma and interstitial space fluid of skeletal muscle during an oral glucose tolerance test and euglycaemic hyperinsulinaemic clamp conditions, respectively. For this purpose we employed in vivo microdialysis of skeletal muscle in conjunction with an ultrasensitive insulin assay in eight healthy lean male volunteers (aged 25 +/- 1 years).

RESULTS

Insulin concentrations at baseline were 48 +/- 8 pmol x L(-1) in plasma and 19 +/- 4 pmol x L(-1) in the interstitium (P = 0.002). The mean interstitium to plasma ratio at baseline was 0.48 +/- 0.09 pmol x L(-1). During the oral glucose tolerance test the interstitium to plasma ratio remained unchanged (0.43 +/- 0.12, P = NS vs. baseline), but was significantly reduced during euglycaemic hyperinsulinaemic clamp conditions at steady-state hyperinsulinaemia (0.12 +/- 0.01, P = 0.01 vs. baseline).

CONCLUSION

In summary there is a substantial transcapillary insulin gradient in healthy human skeletal muscle under baseline and glucose-stimulated conditions. Our findings support the hypothesis of a saturable transcapillary insulin transport representing a partly rate-limiting step for insulin action.

Surgical infants on total parenteral nutrition have impaired cytokine responses to microbial challenge

BACKGROUND/PURPOSE

Cytokines are essential for the prevention of microbial infections. Total parenteral nutrition (TPN) in infancy is associated with an increased risk of infection, and this could be related to altered cytokine production. The aim of the study was to determine if cytokine production is altered in monocytes from surgical infants receiving TPN.

METHODS

There were 3 study groups: (a) infants receiving TPN, (b) enterally fed healthy control infants, and (c) enterally fed healthy control adults. Blood samples were incubated with either Escherichia coli LPS, Staphylococcus epidermidis, or with medium alone. Flow cytometry was used to measure monocyte intracellular cytokine: tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, IL-1beta.

RESULTS

After LPS stimulation, the percent of monocytes producing TNF-alpha and IL-6 were lower in infants on TPN than both control infants and adults. This was most apparent for TNF-alpha. The difference for IL-1beta was significant only between infant on TPN and control adults. When blood was stimulated with S. epidermidis, all 3 cytokines were significantly lower in the TPN group compared with control adults. However, the differences between infants on TPN and infant controls only reached statistical significance for IL-6.

CONCLUSIONS

The inflammatory response to bacterial challenge is impaired in infants on TPN compared with enterally fed infants or adults. The pattern of this response may be dependent on the nature of the microbial challenge. Our results indicate that the susceptibility of TPN-fed surgical infants to bacterial infections may in part be caused by impaired cytokine responses after bacterial invasion.

[Epidermoid cyst of the fourth ventricle: four case reports]

Patients with epidermoid cyst of the fourth ventricle usually present with headaches and/or disequilibrium. These cysts are characterized by a focal lesion that is nearly isodense to CSF at CT and nearly isointense to CSF on T1W and T2W MR images. MRI using FLAIR and diffusion weighted images as well as 3D CISS acquisitions is useful to better characterize the lesions and their relation with the vermis, foramen magnum and CP angle cisterns. DWI images are useful for postsurgical evaluation of residual tumor. Extension of the cyst into the CP angle cisterns usually precludes complete surgical resection.

Kawasaki disease: an evidence based approach to diagnosis, treatment, and proposals for future research

This article proposes a clinical guideline for the diagnosis and treatment of Kawasaki disease in the UK based on the best available evidence to date, and highlights areas of practice where evidence is anecdotal or based on retrospective data. Future research as proposed by the London Kawasaki Disease Research Group is outlined, and clinicians are invited to prospectively enroll their suspected cases into this collaborative research project.

Angioplasty increases target site concentrations of ciprofloxacin in patients with peripheral arterial occlusive disease

OBJECTIVE

Patients with peripheral arterial occlusive disease are prone to soft tissue infections and frequently require antibiotics. To date, however, it is not known whether improvement of arterial blood flow by angioplasty of stenosis increases antibiotic concentrations in ischemic lesions.

PATIENTS AND METHODS

All patients were scheduled to undergo elective percutaneous transluminal angioplasty (n = 10). Following a single, 400-mg dose of ciprofloxacin, drug concentrations in plasma, ischemic and healthy soft tissue; arterial peak systolic velocity; and ankle-brachial pressure index were assessed before and after angioplasty. Unbound ciprofloxacin concentrations were measured at the site of infection with use of in vivo microdialysis.

RESULTS

Angioplasty increased peak systolic velocity and ankle-brachial pressure index compared with baseline (P <.002). Before angioplasty area under concentration-time curve (AUC(0-300)) values for ciprofloxacin were lower in ischemic tissue than in healthy tissue, with median values of 7.1 mg.h/L (range, 3.5-13.0) and 11.3 mg.h/L (range, 3.4-19.0), respectively (P =.03). After angioplasty AUC(0-300) values were identical in ischemic and healthy adipose tissue; median AUC(0-300) values were 8.0 mg.h/L (range, 4.0-20.7) and 8.5 mg.h/L (range, 4.4-22.9), respectively (P =.7). A combined in vivo pharmacokinetic/in vitro pharmacodynamic simulation based on tissue concentration data indicates that this difference in pharmacokinetics is also reflected in antimicrobial effect.

CONCLUSION

Antibiotic concentrations are reduced significantly in ischemic lesions compared to those of healthy adipose tissue in patients with peripheral arterial occlusive disease. From the present data it might be speculated that improvement of arterial blood flow at the affected extremity is associated with increased cure rates of soft tissue infections in these patients.

Characterization of four CD18 mutants in leucocyte adhesion deficient (LAD) patients with differential capacities to support expression and function of the CD11/CD18 integrins LFA-1, Mac-1 and p150,95

Leucocyte adhesion deficiency (LAD) is a hereditary disorder caused by mutations in the CD18 (beta2 integrin) gene. Four missense mutations have been identified in three patients. CD18(A270V) supports, at a diminished level, CD11b/CD18 (Mac-1, alphaMbeta2 integrin) and CD11c/CD18 (p150,95, alphaXbeta2 integrin) expression and function but not CD11a/CD18 (LFA-1, alphaLbeta2 integrin) expression. Conversely, CD18(A341P) supports a limited level of expression and function of CD11a/CD18, but not of the other two CD11/CD18 antigens. CD18(C590R) and CD18(R593C) show a decreasing capacity to associate with the CD11a, CD11c and CD11b subunits. Transfectants expressing the CD11a/CD18 with the C590R and R593C mutations are more adhesive than transfectants expressing wild-type LFA-1, and express the reporter epitope of the monoclonal antibody 24 constitutively. Thus, the four mutations affect CD18 differently in its capacities to support CD11/CD18 expression and adhesion. These results not only provide a biochemical account for the clinical diversity of patients with leucocyte adhesion deficiency, but also offer novel insights into the structural basis of interaction between the alpha and beta subunits, which is an integral component in our understanding of integrin-mediated adhesion and its regulation.

Penetration of dacarbazine and its active metabolite 5-aminoimidazole-4-carboxamide into cutaneous metastases of human malignant melanoma

BACKGROUND

Dacarbazine has been on the market for approximately 3 decades but remains the most effective single agent available for the therapy of metastatic malignant melanoma (MMM). Most MMMs, however, respond poorly to dacarbazine therapy. Apart from tumor resistance at a molecular level, several studies support the notion that therapeutic failure in tumor therapy also might be attributed to an impaired transcapillary drug transfer.

METHODS

On the basis of this hypothesis, the authors measured intratumor transcapillary transfer rates of dacarbazine and its active metabolite 5-aminoimidazole-4-carboxamide (AIC) by in vivo microdialysis after intravenous administration of dacarbazine at doses of 200 mg/m(2) to 1000 mg/m(2) (n = 7) in patients suffering from MMM.

RESULTS

For all doses, area under the concentration curve (AUC) values for dacarbazine and AIC were not significantly different between plasma and tumor interstitium with AUC(tumor)/AUC(plasma) ratios of 0.97 +/- 0.08 (mean +/- standard error of the mean) for dacarbazine and 0.76 +/- 0.22 for AIC. AUC(0-240) values for dacarbazine and AIC measured in plasma correlated closely with corresponding AUC(0-240)values measured in the interstitium of MMMs with values of r(s) = 0.82 (P = 0.042) and r(s) = 0.90 (P = 0.037), respectively.

CONCLUSIONS

The results of this study indicate favorable tumor penetration characteristics of dacarbazine and its active metabolite AIC. The relative lack of response to antineoplastic therapy with dacarbazine, thus might be explained by resistance of melanoma cells at a molecular level rather than by an inability of dacarbazine and AIC to penetrate into the interstitium of MMM.

Immunomodulatory effects of breast milk oligosaccharides

Breast milk oligosaccharides are excreted in urine in amounts that suggest that they may exist in the circulation at levels compatible with a physiological function. Some oligosaccharides have structural similarity to cellular adhesion molecules and may influence adhesion of cells in breast fed infants. In this study, breast milk oligosaccharides were purified and incubated in assays of cell adhesion. They were found to inhibit neutrophil adhesion to stimulated vascular endothelial cells in a dose dependent fashion. In contrast they enhanced platelet-neutrophil complex formation. These results indicate that breast milk oligosaccharides may play a physiological role in modulating cellular adhesion in vivo.

Conversion of amino acids into aroma compounds by cell-free extracts of Lactobacillus helveticus

AIMS

Lactobacillus helveticus is an essential starter in Swiss-type cheeses such as Emmental. This study was to determine whether cell-free extracts of Lact. helveticus were able to convert free amino acids into neutral volatile aroma compounds at the pH and temperature occurring in cheese.

METHODS AND RESULTS

A mix of branched-chain (Leu, Ile, Val), aromatic (Tyr, Phe) and sulphur (Met) amino acids was incubated for 7 days, at pH 5.7 and 24 degrees C, with cell-free extracts of six strains. The amino acids were all transaminated into the corresponding keto acids when an amino group acceptor (alpha-ketoglutaric acid) was provided. Phe and Tyr were transaminated the most efficiently, followed by Leu, Met, Ile and Val. Three major volatile compounds were detected by GC-MS: benzaldehyde, dimethyl disulphide and 2-methyl propanol. Whatever the strain, benzaldehyde was produced in the highest quantity (0.25-1 micromol l(-1) mg(-1) protein).

CONCLUSIONS, SIGNIFICANCE AND IMPACT OF THE STUDY

Lactobacillus helveticus intracellular enzymes could significantly contribute to the production of aroma compounds from amino acid catabolism.

Contributions of Neisseria meningitidis LPS and non-LPS to proinflammatory cytokine response

To determine the relative contribution of lipopolysaccharide (LPS) and non-LPS components of Neisseria meningitidis to the pathogenesis of meningococcal sepsis, this study quantitatively compared cytokine induction by isolated LPS, wild-type serogroup B meningococci (strain H44/76), and LPS-deficient mutant meningococci (strain H44/76[pLAK33]). Stimulation of human peripheral-blood mononuclear cells with wild-type and LPS-deficient meningococci showed that non-LPS components of meningococci are responsible for a substantial part of tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta production and virtually all interferon (IFN)-gamma production. Based on tricine sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of LPS in proteinase K-treated lysates of N. meningitidis H44/76, a quantitative comparison was made between the cytokine-inducing capacity of isolated and purified LPS and LPS-containing meningococci. At concentrations of >10(7) bacteria/mL, intact bacteria were more potent cytokine inductors than equivalent amounts of isolated LPS, and cytokine induction by non-LPS components was additive to that by LPS. Experiments with mice showed that non-LPS components of meningococci were able to induce cytokine production and mortality. The principal conclusion is that non-LPS parts of N. meningitidis may play a role in the pathogenesis of meningococcal sepsis by inducing substantial TNF-alpha, IL-1beta, and IFN-gamma production.

Dendritic cell activation and cytokine production induced by group B Neisseria meningitidis: interleukin-12 production depends on lipopolysaccharide expression in intact bacteria

Interactions between dendritic cells (DCs) and microbial pathogens are fundamental to the generation of innate and adaptive immune responses. Upon stimulation with bacteria or bacterial components such as lipopolysaccharide (LPS), immature DCs undergo a maturation process that involves expression of costimulatory molecules, HLA molecules, and cytokines and chemokines, thus providing critical signals for lymphocyte development and differentiation. In this study, we investigated the response of in vitro-generated human DCs to a serogroup B strain of Neisseria meningitidis compared to an isogenic mutant lpxA strain totally deficient in LPS and purified LPS from the same strain. We show that the parent strain, lpxA mutant, and meningococcal LPS all induce DC maturation as measured by increased surface expression of costimulatory molecules and HLA class I and II molecules. Both the parent and lpxA strains induced production of tumor necrosis factor alpha (TNF-alpha), interleukin-1alpha (IL-1alpha), and IL-6 in DCs, although the parent was the more potent stimulus. In contrast, high-level IL-12 production was only seen with the parent strain. Compared to intact bacteria, purified LPS was a very poor inducer of IL-1alpha, IL-6, and TNF-alpha production and induced no detectable IL-12. Addition of exogenous LPS to the lpxA strain only partially restored cytokine production and did not restore IL-12 production. These data show that non-LPS components of N. meningitidis induce DC maturation, but that LPS in the context of the intact bacterium is required for high-level cytokine production, especially that of IL-12. These findings may be useful in assessing components of N. meningitidis as potential vaccine candidates.

Ischemic preconditioning prevents endothelial injury and systemic neutrophil activation during ischemia-reperfusion in humans in vivo

BACKGROUND

Endothelial dysfunction leading to neutrophil infiltration of tissues has been implicated in tissue injury caused by ischemia-reperfusion (IR). Tissue injury during IR can be reduced by prior ischemic preconditioning (IPC). In humans, it is unclear whether endothelial dysfunction occurs during IR or whether IPC offers protection against endothelial dysfunction and inflammatory cell activation. We studied the effects of experimental IR on endothelial and neutrophil function in the human forearm in vivo and examined the protection afforded by IPC.

METHOD AND RESULTS

The forearm was made ischemic for 20 minutes by inflating a blood pressure cuff to 200 mm Hg. We assessed endothelial function of conduit (radial artery flow-mediated dilation) and resistance vessels (blood flow responses to intra-arterial infusion of the endothelium-dependent dilator acetylcholine) in healthy volunteers before and after IR. IR reduced flow-mediated dilation of the radial artery at 15 minutes of reperfusion (7.7+/-1.5% to 3.5+/-0.9%) and the dilator response of resistance vessels to acetylcholine at 15, 30, and 60 minutes of reperfusion. IR did not reduce the dilator response of the radial artery to glyceryltrinitrate and only caused a small reduction of glyceryltrinitrate-induced dilation of resistance vessels at 60 minutes of reperfusion. IR caused an increase in neutrophil CD11b expression and platelet-neutrophil complexes in the circulating blood. IPC (three 5-minute episodes of ischemia) before IR prevented endothelial dysfunction and neutrophil activation.

CONCLUSIONS

A clinically relevant period of ischemia-reperfusion causes profound and sustained endothelial dysfunction and systemic neutrophil activation. IPC attenuates both of these effects in humans.

[Catheter ablation of supraventricular tachyarrhythmias]

The term "supraventricular tachyarrhythmia" summarizes electrophysiologically different arrhythmias. After detection of the mechanism of the present arrhythmia, the weak part of the reentrant circuit has to be identified using different mapping techniques. The catheter ablation is widely used as focal ablation (sinus tachycardia, ectopic atrial tachycardia, focal atrial fibrillation) or for interruption of conducting pathways (accessory pathways, AV nodal reentrant tachycardia). A single ablation line should be created in isthmus-dependent atrial flutter or in incisional tachycardias, which is less used now-a-days. Multiple ablation lines are needed for ablation of atrial fibrillation, which is a method investigated in arrhythmia centers only. Some arrhythmias are less well understood, not localizable and therefore not curatively treated with ablation techniques. Newer three-dimensional mapping methods may help in this situation. The challenge at the present time is the catheter ablation of atrial fibrillation.

School-age consequences of birth weight less than 750 g: a review and update

Recent advances in perinatal care have led to the survival of increasing numbers of children born at the lower limits of viability. Children with very low birth weight (LBW; less than 1,500 g, 3 lb 5 oz) have been studied extensively. Findings document poorer outcomes relative to normal birth weight term-born controls in neurologic and health status, cognitive-neuropsychological skills, school performance, academic achievement, and behavior. This report reviews current knowledge regarding LBW children, with special emphasis on outcomes for children with birth weight less than 750 g (1 lb 10 oz). Results from an ongoing longitudinal study suggest a gradient of sequelae, with poorer outcomes in less than 750 g birth weight children compared to both 750 g to 1,499 g birth weight children and term-born controls. Children with less than 750 g birth weight fail to catch up with their peers over time and may even be at risk for age-related increases in sequelae. Outcomes are highly variable but related to neonatal medical complications of prematurity and social risk factors. Further research is needed to understand the etiology and neuropathological basis of sequelae, the long-term developmental implications of LBW, and treatment needs.

The role of the collectin system in pulmonary defence

The human collectin system comprises the serum protein, mannose- binding lectin and the hydrophilic surfactant proteins A and D. The three proteins possess structural and functional similarities and are important components of innate immunity. Through a variety of mechanisms, including direct opsonisation and complement activation, they assist in host defence against a wide array of micro-organisms. Investigation of the roles of the surfactant proteins in pulmonary disease has been assisted recently by the development of transgenic knockout mice. Animals deficient in these proteins display susceptibility to certain bacterial and viral pathogens, stimulating research into the role of polymorphisms in these genes in human respiratory disease. The role of MBL in human pulmonary disease is less well established, although accumulating evidence suggests that it is a modifier for lung disease in tuberculosis and cystic fibrosis.

Pharmacokinetics of emedastine difumarate, a new anti-histaminic agent in patients with renal impairment

OBJECTIVE

Emedastine difumarate is a new H1 receptor antagonist with well defined pharmacokinetic and pharmacodynamic profiles in healthy volunteers. However, to date it is not known whether impaired renal function in patients with chronic renal insufficiency affects its pharmacokinetics and probably also its tolerability. Therefore, we here set out to compare the pharmacokinetics of emedastine difumarate in patients suffering from different degrees of renal failure with a control group of healthy volunteers.

METHODS AND RESULTS

For this purpose we conducted an open, single-centre, comparative parallel group study in patients and healthy volunteers. Emedastine difumarate 2 mg was administered orally to the study population in single and seven repetitive doses twice daily (b.i.d.). Pharmacokinetics differed markedly between volunteers (n = 6) and patients (n = 17). The maximum serum concentration of emedastine (Cmax), area under the serum concentration-time curve, mean residence time and terminal disposition half-life were significantly higher in patients (P < 0.05), while time to reach Cmax and apparent volume of disposition were not statistically different after single and repeated (steady-state) oral administrations. Blood pressure and heart rate were also not affected by the study medication.

CONCLUSION

The present study shows that impaired renal function alters the pharmacokinetics of emedastine in plasma. Thus, dose adjustment of emedastine difumarate is advisable in patients with impaired renal function.