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N J Klein

Publications and source records attributed to N J Klein.

At least 19 recordsLinked to original sources
PubMed2006

Decreased monocyte class II MHC expression following major abdominal surgery in children is related to operative stress.

Monocyte class II major histocompatibility complex (MHC) expression is necessary for antigen presentation and stimulation of T-cells. The aim of this study was to correlate monocyte class II MHC response to operative stress in children and the possible influence of cytokines in the postoperative period. We studied 21 children undergoing elective abdominal surgery. Operative stress score (OSS) was calculated. Monocyte class II MHC expression was measured preoperatively, immediately after surgery, 24 and 48 h postoperatively, using flow cytometry. Class II MHC is expressed as mean fluorescence intensity (MFI) of monocytes expressing MHC (mean +/- SD). Cytokine levels (interleukins 1ra, 6, and 10, and tumor necrosis factor-alpha) were also measured. Data between time points were compared using repeated measures ANOVA. There was an immediate postoperative decrease in class II MHC expression, with lowest levels 24 h postoperatively (preoperative 50 +/- 23.6, 24 h 18.2 +/- 9.4, P < 0.0001 vs. preoperative). At 48 h there was partial recovery in class II MHC, but levels were still significantly lower than preoperative (23.9 +/- 11.1, P < 0.001). The degree of monocyte depression was related to the magnitude of operative stress. Patients who had OSS <10 displayed some recovery in expression at 48 h 25.5 +/- 11.1), whereas in patients with OSS > or = 10 (severe surgical stress), expression further decreased at 48 h (MFI 14.0 +/- 0.1). There was an elevation of interleukin-1ra in the immediate postoperative period in both groups. There was no elevation in the other cytokines. Abdominal surgery in children decreases monocyte MHC expression. Class II MHC depression was related to magnitude of surgical trauma, implying that more severe immuneparesis follows surgery of greater magnitude. This may predispose to postoperative infection.

Abdomen↗
PubMed2006

Endotoxin immunity and the development of the systemic inflammatory response syndrome in critically ill children.

BACKGROUND: The systemic inflammatory response syndrome (SIRS) may be triggered by endotoxin. Humans have antibodies directed against the core of endotoxin (endotoxin core antibodies, EndoCAb) that appear to be protective following surgery and in sepsis. We hypothesised that children with elevated antibodies to endotoxin core would be less likely to develop SIRS in their initial period on intensive care. Because of the existing literature we defined two sub-groups according to the primary reason for ICU admission: infection and non-infection. METHODS: We recruited 139 consecutive patients admitted to a paediatric intensive care unit (PICU) with more than one organ failure for longer than 12 h as part of another study. Patients were classified on admission to PICU as having an infectious or a non-infections diagnosis. The occurrence of SIRS within 48 h of admission was recorded along with detailed clinical and demographic data, EndoCAb concentration and the potential confounding variables C-reactive protein and mannose-binding lectin. RESULTS: In the 71 patients admitted without infection (primarily post-operative and head injured) IgG EndoCAb was significantly lower in patients who developed SIRS than those who did not (72 vs. 131 MU/ml), independent of potential confounding variables. In patients with infection there was no significant difference in IgG EndoCAb between children developing SIRS and those who did not (111 vs. 80 MU/ml). CONCLUSION: Head injured and post-operative patients admitted to PICU who develop early SIRS have significantly lower serum IgG EndoCAb levels than those who do not.

Adolescent↗
PubMed2005

Mannose-binding lectin: do we need it?

Mannose-binding lectin (MBL) deficiency has now been recognised for 15 years. Numerous studies have shown that MBL deficiency is associated with an increased susceptibility to a range of infections. However, the importance of MBL, in defence against infection, is still debated. This article discusses recent developments in MBL research and explores how MBL may be operating in the setting of modern medical practice.

Animals↗
PubMed2005

Susceptibility to infection in patients with neutropenia: the role of the innate immune system.

Chemotherapy-induced neutropenia increases the risk of infection. There appears to be a wide variability in the severity and length of infective episodes. Susceptibility to infections is determined by the underlying malignant disease and its treatment, environmental factors (e.g. nutritional state of the patient and hygiene) and genetically determined variations of the immune system. The majority of primary immunodeficiencies are rare (c. frequency one in 10 000), whereas some genetic polymorphisms in the innate immune system, such as profound mannose-binding lectin deficiency, are much more common (c. frequency one in 10). Here, we review the potential role of the innate immune system in determining susceptibility to infections in patients with neutropenia.

Antineoplastic Agents↗
PubMed2004

Interleukin-4 increases the permeability of human endothelial cells in culture.

BACKGROUND: IL-4 plays a key role in the induction of allergic inflammation, but its role as an effector molecule is less well-established. Although some observations suggest that IL-4 may mediate increased vascular permeability, which is a characteristic feature of allergic inflammation, evidence for a direct effect on endothelial cell permeability is lacking. OBJECTIVE: To determine the effect of human IL-4 on the albumin permeability of cultured human endothelial cells. METHODS: Human umbilical vein endothelial cells were cultured on permeable membranes and the albumin permeability of endothelial monolayers was measured with and without exposure to recombinant human IL-4. Endothelial cells were exposed to various concentrations of IL-4 (0.001-100 U/mL), for various durations (6-24 h), either in the presence or absence of anti-IL-4 antibody. Recovery of endothelial barrier function following exposure to IL-4 was also examined. RESULTS: IL-4 induced a dose-dependent, reversible increase in endothelial permeability to albumin. Low concentrations of IL-4 (1 U/mL) induced a significant increase in endothelial permeability (P=0.004). IL-4-mediated endothelial leak occurred rapidly, within 6 h of exposure. CONCLUSIONS: IL-4 has the capacity to induce vascular leak by a direct effect on cultured endothelial cells, suggesting a potential effector role for IL-4 in the pathogenesis of vascular leak in allergic diseases.

Capillary Permeability↗
PubMed2004

High-level endothelial E-selectin (CD62E) cell adhesion molecule expression by a lipopolysaccharide-deficient strain of Neisseria meningitidis despite poor activation of NF-kappaB transcription factor.

Binding of host inflammatory cells to the endothelium is a critical contributor to the vascular damage characteristic of severe meningococcal disease and is regulated by endothelial cell adhesion molecules such as ICAM-1, VCAM-1 and CD62E. Intact meningococci induce far higher levels of CD62E than lipopolysaccharide (LPS) alone, whereas LPS is at least as potent as meningococci at inducing both VCAM-1 and ICAM-1 expression. This suggests that meningococci possess additional factors other than LPS present in whole bacteria that result in differential adhesion molecule expression. To investigate this possibility, we studied the capacity of an LPS-deficient isogenic strain of serogroup B Neisseria meningitidis H44/76 (lpxA-) to induce endothelial cell adhesion molecule expression and translocation of the transcription factor NF-kappaB, and compared it to both parent and unencapsulated strains of both B1940 and H44/76 and purified LPS. Although the LPS-deficient isogenic mutant of strain H44/76 was found to be a poor inducer of NF-kappaB, it induced higher levels of CD62E expression than LPS alone. These data provide evidence that intact meningococci induce a range of signals in the endothelium that are distinct from those seen with purified LPS alone and that they occur in a LPS-dependent and LPS-independent manner. These signals may explain the potent effects of N. meningitidis on CD62E expression on vascular endothelium and provide a basis for the complex endothelial dysregulation seen in meningococcal sepsis.

Cells, Cultured↗
PubMed2003

Gut overgrowth with abnormal flora: the missing link in parenteral nutrition-related sepsis in surgical neonates.

BACKGROUND AND AIMS: Patients receiving parenteral nutrition are at risk of septicaemia. Intestinal dysmotility and impaired gut immunity due to parenteral nutrition promote bacterial overgrowth. Gut overgrowth with aerobic Gram-negative bacilli (AGNB) impairs systemic immunity. The aim of this study was to determine the potential role of gut overgrowth with AGNB in the pathogenesis of septicaemia related to parenteral nutrition. METHODS: A prospective 5 y study of surgical infants less than 6 months of age was undertaken. Surveillance samples of the oropharynx and gut were obtained at the start of parenteral nutrition and thereafter twice weekly, to detect AGNB carriage. Blood cultures were taken on clinical indication only. RESULTS: Two-hundred and eight infants received parenteral nutrition for 6271 days (median 13 days, range 1-512 days). The incidence of AGNB carriage was 42%, whilst the septicaemia rate was 15%. Eighty-four percent of septicaemic infants carried AGNB, whilst 16% never carried AGNB (P<0.005). Carriage developed significantly earlier than septicaemia. CONCLUSIONS: The incidence of septicaemia was significantly greater in the subset of abnormal carriers. Although gut overgrowth with abnormal flora reflects illness severity, the fact that it preceded septicaemia implicates AGNB overgrowth, per se, as a contributory factor in the development of septicaemia related to parenteral nutrition. Prevention is unlikely to be successful if it ignores the abnormal flora.

Bacteremia↗
PubMed2003

Severe meningococcal disease is characterized by early neutrophil but not platelet activation and increased formation and consumption of platelet-neutrophil complexes.

Approximately 25% of polymorphonuclear leukocytes (PMNL) circulate in heterotypic complexes with one or more activated platelets. These platelet-neutrophil complexes (PNC) require platelet CD62P expression for their formation and represent activated subpopulations of both cell types. In this study, we have investigated the presence, time course, and mechanisms of PNC formation in 32 cases of severe pediatric meningococcal disease (MD) requiring intensive care. There were marked early increases in PMNL CD11b/CD18 expression and activation, and reduced CD62L expression compared with intensive care unit control cases. Minimal platelet expression of the active form of alphaIIbbeta3 (GpIIb/IIIa) was seen. PNC were reduced on presentation and fell to very low levels after 24 h. Immunostaining of skin biopsies demonstrated that PNC appear outside the circulation in MD. In vitro studies of anticoagulated whole blood inoculated with Neisseria meningitidis supported these clinical findings with marked increases in PMNL CD11b/CD18 expression and activation but no detectable changes in platelet-activated alphaIIbbeta3 or CD62P expression. In vitro PMNL activation with N. meningitidis (or other agonists) potentiated the formation of PNC in response to platelet activation with adenine diphosphate. Therefore, in severe MD, PMNL activation is likely to promote PNC formation, and we suggest that the reduced levels of PNC seen in established MD reflect rapid loss of PNC from the circulation rather than reduced formation.

Antigens, CD↗
PubMed2001

Mannose-binding lectin regulates the inflammatory response of human professional phagocytes to Neisseria meningitidis serogroup B.

The influence of the innate immune protein mannose-binding lectin (MBL) on the response of human phagocytes to Neisseria meningitidis was investigated. MBL increased the association of killed meningococci with neutrophils, monocytes, and macrophages by increasing the proportion of cells that recognized bacteria. MBL down-regulated the normal change in expression of the leukocyte adhesion molecules CD11b and CD62L. In an ex vivo model, the addition of MBL to the blood of MBL-deficient donors influenced the production of monocyte-derived inflammatory cytokines. The addition of high concentrations of MBL (>6 microg/mL) profoundly decreased the production of interleukin (IL)-6, IL-1beta, and tumor necrosis factor-alpha by monocytes in response to meningococci, whereas lower concentrations enhanced the production of IL-6 and IL-1beta. These results suggest that MBL not only is involved in complement activation but also is a potent regulator of inflammatory pathways and, as such, may affect the severity of meningococcal disease.

CD11 Antigens↗
PubMed2001

Deficiency of mannose-binding lectin and burden of infection in children with malignancy: a prospective study.

BACKGROUND: Infection is a major cause of morbidity and mortality in children with malignancy. Individuals with serum deficient in mannose-binding lectin (MBL)-an important component of the innate immune system-are more susceptible to infection than those with adequate concentrations. In this study, we investigated the capacity of this protein to influence infectious complications in children undergoing treatment for malignancy. METHODS: We enrolled 100 children receiving chemotherapy for malignancy at a children's hospital in London, UK. The frequency, duration, and causes of febrile neutropenic episodes were recorded, and MBL genotype and phenotype were determined by heteroduplex analysis and ELISAs, respectively. Serial MBL concentrations were also measured in patients during febrile episodes, and the results correlated with the MBL genotype (A/A indicating wild type, O/O indicating homozygous for MBL structural-gene mutations, and A/O indicating heterozygous for such mutations). FINDINGS: In the A/A patients, MBL concentrations almost doubled by day 7 of the febrile neutropenic episode before declining by day 14 (p=0.004). By contrast, in patients with MBL mutations, concentrations did not alter significantly during the neutropenic episode. In the 6 months after initial diagnosis, most patients had at least one febrile neutropenic episode, but the median duration in patients with MBL mutations was twice as long as that in children with the wildtype genotype (20.5 days vs 10.0 days; p=0.014). Individuals with the lowest serum MBL concentrations at the time of diagnosis (<1000 microg/L) had a higher median number of days of febrile neutropenia than did individuals with higher concentrations of MBL (p=0.012). INTERPRETATION: MBL deficiency seems to have an important influence on the duration of febrile neutropenic episodes in children with malignancy. This finding suggests that MBL infusions could represent a new therapeutic approach which would aid the management of chemotherapy-induced complications in this population of children.

Adolescent↗
PubMed2001

Mannose-binding lectin accelerates complement activation and increases serum killing of Neisseria meningitidis serogroup C.

The capacity for different lipo-oligosaccharide (LOS) sialylation patterns of Neisseria meningitidis serogroup C to influence the binding and function of the innate humoral component, mannose-binding lectin (MBL), was investigated. By use of flow cytometry and immunogold electron microscopy, a clinical isolate with reduced endogenous LOS sialylation was found to bind more MBL than did strains with higher endogenous sialylation. MBL binding was reduced but not ablated if the same strain was allowed to exogenously sialylate its LOS structures after incubation with cytidine-5'-monophospho-neuraminic acid. MBL binding led to an increased rate of complement activation, with enhanced deposition of the complement components C4 and C5b-9, and this correlated with an increase in bactericidal activity. LOS sialylation appears to be an important determinant of MBL binding to N. meningitidis and can modulate complement-dependent killing of the bacterium. These findings could explain the observed susceptibility to meningococcal disease of individuals genetically deficient in MBL.

Acute-Phase Proteins↗
PubMed2001

Poststreptococcal acute disseminated encephalomyelitis with basal ganglia involvement and auto-reactive antibasal ganglia antibodies.

Antibasal ganglia antibodies (ABGA) are associated with Sydenham's chorea and pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections. We present 10 patients with acute disseminated encephalomyelitis (ADEM) associated with Group A beta hemolytic streptococcal infection. The clinical phenotype was novel, with 50% having a dystonic extrapyramidal movement disorder, and 70% a behavioral syndrome. None of the patients had rheumatic fever or Sydenham's chorea. Enzyme-linked immunosorbent assay, Western immunoblotting, and immunohistochemistry were used to detect ABGA. Neurological (n = 40) and streptococcal (n = 40) controls were used for comparison. Enzyme-linked immunosorbent assay results showed significantly elevated ABGA in the patients with poststreptococcal ADEM. Western immunoblotting demonstrated ABGA reactivity to three dominant protein bands of 60, 67, or 80 kDa; a finding not reproduced in controls. Fluorescent immunohistochemistry demonstrated specific binding to large striatal neurones, which was not seen in controls. Streptococcal serology was also significantly elevated in the poststreptococcal ADEM group compared with neurological controls. Magnetic resonance imaging studies showed hyperintense basal ganglia in 80% of patients with poststreptococcal ADEM, compared to 18% of patients with nonstreptococcal ADEM. These findings support a new subgroup of postinfectious autoimmune inflammatory disorders associated with Group A beta hemolytic streptococcus, abnormal basal ganglia imaging, and elevated ABGA.

Acute Disease↗
PubMed2001

Mannose-binding lectin: targeting the microbial world for complement attack and opsonophagocytosis.

Mannose-binding lectin (MBL) is an important constituent of the innate immune system. This protein binds through multiple lectin domains to the repeating sugar arrays that decorate many microbial surfaces, and is then able to activate the complement system through a specific protease called MBL-associated protease-2. We have used flow cytometry to study both the binding of MBL to microorganisms and the subsequent activation of complement. For selected Gram-negative organisms, such as Salmonella and Neisseria, we have examined the relative roles of lipopolysaccharide (LPS) structure and capsule in determining binding and conclude that the LPS is of major importance. Our results from studies with several clinically relevant organisms also show that MBL binding detected by flow cytometry leads to measurable activation of purified C4, suggesting that the bound lectin is capable of initiating opsonophagocytosis and/or bacterial lysis. There is an increasing literature suggesting that MBL deficiency, which mainly results from three relatively common single point mutations in exon 1 of the gene, predisposes both to infection by extracellular pathogens and to autoimmune disease. In addition, the protein also modulates disease severity, at least in part through a complex, dose-dependent influence on cytokine production. The mechanisms and signalling pathways involved in such processes remain to be elucidated.

Bacterial Capsules↗
PubMed2001

Differential recognition of obligate anaerobic bacteria by human mannose-binding lectin.

Deficiency of the innate, humoral immune component mannose-binding lectin (MBL) predisposes individuals to a variety of infections, but the importance of MBL in infection by anaerobes has not been addressed. The attachment of MBL to a wide range of anaerobic bacteria associated with human disease and colonization was surveyed. The results suggest that for the species we examined, resistance to MBL binding may be associated with organisms that are more commonly pathogenic and that MBL binding to some bacteria may be phase variable.

Bacteria, Anaerobic↗
PubMed2001

Management of primary nocturnal enuresis.

Most parents believe that their child should not be wetting the bed by age 5. Statistics show that 10% to 20% of 5 year olds continue with a least one episode of nocturnal enuresis per month. There is evidence that successful treatment leads to improved self-concept in children (Moffatt, Kato, & Pless, 1987). Treatment consists of various behavior modifications or pharmacologic regimes. Nurses and nurse practitioners in family practice, pediatric practice, school health, and urologic practice are in ideal roles to seek out and manage children with primary nocturnal enuresis.

Child↗