PubMed Health⌕ Search

Biomedical subjects

D J Reen

Publications and source records attributed to D J Reen.

At least 19 recordsLinked to original sources
PubMed1996

Diminished production of prostaglandin E2 by monocytes of newborns is due to altered fatty acid membrane content and reduced cyclooxygenase activity.

To determine the biochemical basis for reduced PGE2 expression by cord blood monocytes relative to adult peripheral blood monocytes, fatty acid composition of cell membranes together with the amount and activity of enzymes involved in the cyclooxygenase pathway were investigated. Gas chromatographic analysis of mononuclear cell fatty acids showed a significant reduction in long chain fatty acids, including arachidonic acid. Acylase and phospholipase A2 activity, together with lipocortin 1 levels, were similar in cord and adult monocytes. No difference in amounts of the 70-kDa cyclooxygenase type 1 enzyme was observed between the monocyte sources. The 74k-Da cyclooxygenase type 2 enzyme was synthesized de novo upon LPS stimulation in comparable amounts in both cord and adult monocytes, with both monocyte types responding with equal sensitivity to LPS. The ability of microsomes, prepared from cord monocytes, to convert arachidonic acid into eicosanoids of the cyclooxygenase pathway was reduced. In contrast, the ability of acetylated microsomes to convert PGG2 to PGE2 was comparable, suggesting that the deficiency in PGE2 production by cord monocytes is due to reduced activity, specifically at the cyclooxygenase-active site rather than the peroxidase active site. In conclusion, it appears that both reduced fatty acid content and diminished cyclooxygenase activity are responsible for diminished eicosanoid production by cord monocytes.

Acetylation↗
PubMed1996

Is a histologically normal appendix following emergency appendicectomy alway normal?

BACKGROUND: Appendixes removed from patients with suspected appendicitis often appear normal on histological examination. We examined appendix specimens for expression of abnormal amounts of cytokines, an indicator of an inflammatory response. METHODS: Tumour necrosis factor alpha (TNFalpha) and interleukin-2 (IL-2) expression was measured by in-situ hybridisation in ten specimens from patients with acute appendicitis, 12 normal appendix specimens removed from patients undergoing elective abdominal surgery, and 31 appendix specimens from patients with a clinical diagnosis of appendicitis but an appendix histologically classified as normal. Cytokine-specific RNA antisense probes were prepared by in-vitro transcription and digoxigenin (DIG) labelled. In-situ hybridisation was done on 5 micrometer paraffin sections. Tissue sections hybridised by sense probes acted as negative control for each cytokine. Following hybridisation, the probes were detected by alkaline phosphatase labelled anti-DIG monoclonal antibody and visualised by nitroblue tetrazolium staining. FINDINGS: All histologically proven acute appendicitis specimens demonstrated intense cellular TNFalpha mRNA expression in germinal centres and moderate levels of expression throughout the mucosa. IL-2 mRNA was strongly expressed in the lamina propria and only moderately expressed in germinal centres. Normal appendixes all showed almost complete absence of TNFalpha and IL-2 mRNA expression. Seven of the 31 histologically classified normal appendix specimens from patients with a clinical diagnosis of appendicitis demonstrated TNFalpha and IL-2 mRNA expression similar to acute appendicitis specimens in germinal centres, submucosa, and lamina propria layers. INTERPRETATION: TNFalpha and IL-2 mRNA expression is a sensitive marker of inflammation in appendicitis. A substantial proportion of histologically normal appendixes showed clear evidence of an inflammatory response in the form of increased cytokine expression.

Appendectomy↗
PubMed1996

Antigen-independent responsiveness to interleukin-4 demonstrates differential regulation of newborn human T cells.

The low incidence of graft-versus-host disease following clinical use of umbilical cord blood compared to adult bone marrow as a source of stem cells for bone marrow reconstitution, leads to questions concerning the level of immunocompetence of newborn T cells. The maturation and functional status of newborn CD4+ T cells, which are almost exclusively CD45RA+ naive T cells, compared with their adult phenotypic counterparts, is poorly understood. We examined the proliferative response to mitogens and cytokines of CD4/CD45RA+ T cells from adults and newborns, with and without accessory cells. Newborn CD4/CD45RA+ T cells demonstrated a distinct proliferative response profile which was determined by the number of accessory cells present in co-cultures with various stimuli. Newborn CD4/CD45RA+ T cells were particularly responsive to interleukin (IL)-4, IL-4 plus anti-CD2 monoclonal antibodies (mAb) and IL-4 plus phytohemagglutinin (PHA), whereas adult CD4/CD45RA+ T cells were unresponsive under similar conditions. The mitogenic responses of newborn and adult CD4/CD45RA+ T cells to PHA and anti-CD2 mAb, which were equivalent, were directly proportional to the number of accessory cells present, whereas the responsiveness to cytokines was inversely proportional to the number of co-cultured accessory cells. Anti-CD2 responses were much more sensitive to low numbers of accessory cells than PHA. The particular sensitivity of newborn CD4/CD45RA+ T cells to IL-4 represents an antigen-independent T cell activation response which could help promote a Th2 immune response resulting in the newborn.

Adult↗
PubMed1996

Defective neutrophil actin polymerisation and chemotaxis in stressed newborns.

Abnormalities of polymorphonuclear leukocyte (PMN) function contribute to high rates of postoperative infection in the newborn and to the vulnerability of newborns to overwhelming bacterial and fungal sepsis. The authors investigated (1) the effects of major surgery and sepsis on PMN chemotaxis in the newborn and (2) the role of cytoskeletal rearrangements in regulating chemotaxis. The subjects studied included newborns with sepsis (n = 16), newborns who underwent major surgery (n = 7), healthy full-term newborns (n = 21), and healthy adult volunteers (n = 28). Peak actin polymerisation was diminished in all newborns (relative to the adults) after stimulation with formyl methionyl leucyl phenylalanine (FMLP) (10 nmol/L), and with zymosan activated serum (ZAS) (10%). Major surgery and sepsis in newborns caused no further reduction in actin polymerisation. Changes in PMN shape after stimulation with FMLP were reduced in the newborns. PMN chemotaxis was significantly lower in healthy newborns than in adults (17 +/- 4 microns v 24 +/- 5 microns; P < .0001) and was even lower in septic newborns (11 +/- 4 microns; P < .005). Surgery and anaesthesia did not alter chemotaxis.

Actins↗
PubMed1996

Reduced primary antigen-specific T-cell precursor frequencies in neonates is associated with deficient interleukin-2 production.

Clinical evidence has indicated that the neonatal cell-mediated immune response to primary infection is delayed when compared to that of adults with the same primary infection. The mechanisms regulating the development of antigen-specific T-cell immunity in neonates remain to be elucidated. We examined the primary immune response to the non-recall antigen, keyhole limpet haemocyanin (KLH) in adults and neonates in vitro. We report here that conventional bulk culture methods show reduced proliferative responses in neonates although statistical significance was not achieved. Using limiting dilution analysis, the frequencies of KLH-specific T lymphocytes were 10-100-fold lower in neonates when compared to adults. Interleukin-2 (IL-2) production was significantly lower in the supernatants of neonatal mononuclear cells (MNC) stimulated with KLH when compared to adults. Addition of exogenous IL-2 increased precursor frequencies twofold in both adult and newborn cultures. In contrast to the secreted IL-2 levels, IL-2 mRNA expression was higher in antigen-stimulated neonatal MNC preparations, even though proliferation was lower. These observations indicate differential in vitro responsiveness in neonates and adults to primary antigenic challenge. Since no IL-2 was detected in cell lysates, the presence of high levels of IL-2 mRNA and low IL-2 production suggests inability by neonatal MNC to translate IL-2. This deficiency in IL-2 production may explain the reduced precursor frequencies, suggesting failure to recruit T lymphocytes in order to expand the KLH-specific T-cell response. These observations are important for the understanding of the development of primary immune responses and immunological maturation in neonates.

Adult↗
PubMed1996

Regulation of newborn and adult monocytes by PGE2: evidence of comparable differentiation status.

PGE2, which is produced in large amounts by monocytes, is considered to be an important autocrine factor in the regulation of the immune response. Altered sensitivity to PGE2 is known to reflect the differentiation status of monocytes/macrophages. Since newborn monocytes are thought to be less differentiated than adult peripheral blood monocytes, this study was designed to determine whether the diminished newborn monocyte function, relative to adult peripheral blood monocytes, might be the result of an altered autocrine responsiveness to PGE2. Phosphodiesterase activity as well as cAMP and TNF alpha levels in response to PGE2 were measured in newborn and adult monocytes, as an index of sensitivity to PGE2. Basal intracellular cAMP levels were reduced in cord monocytes compared with adult monocytes. Addition of increasing concentrations of PGE2 (10M(-10)-10M-6) caused similar fold increases in intracellular levels of cAMP for both populations. Lipopolysaccharide-induced TNF alpha production was significantly reduced in a similar fashion for both cord and adult monocytes at high (> or = 10(-7)M) PGE2 concentration. Phosphodiesterase activity was comparable in lysates from both populations. This study shows that PGE2 does not differentially influence newborn and adult monocyte responses and therefore that the diminished functional abilities of newborn monocytes is not due to altered autocrine responsiveness.

Adult↗
PubMed1995

Recognition of unusual presentation of natural killer cell leukemia.

Expansion of the natural killer (NK) subset of lymphocytes represents a rare leukemia phenotype with variations in clinical presentation, morphology, surface phenotype, and effector function. This paper reports on a 5-year-old male patient who had an unusual presentation of an NK cell leukemia that was initially diagnosed as neuroblastoma. A bone marrow (BM) aspirate showed clumps of undifferentiated cells with the following phenotype: CD56bright+, CD33dim+, CD45-, CD2-, CD19-, CD16-, and CD57-. Cytochemistry was noncontributory. The patient, having failed to respond to conventional neuroblastoma chemotherapy, was subsequently diagnosed as having NK cell leukemia based on functional in vitro assays. The patient responded to acute lymphoblastic leukemia (ALL) chemotherapy but relapsed 4 weeks into treatment and eventually died 25 weeks after initial presentation. The cell surface phenotype observed is consistent with a rare NK cell subset, the biology of which has not been well defined. Freshly isolated BM cells killed K562 cells in a conventional 51Cr-release assay. Both interleukin-2 (IL-2) and interferon-alpha (IFN-alpha) induced LAK activity against the Daudi cell line. IL-2 induced proliferation of the leukemic cells. TNF-alpha, IFN-gamma, IL-6, IL-1ra, and TGF-beta levels were assessed and found to be concentrated in BM, in contrast to plasma samples. TNF-alpha was present at a high concentration in BM (150.9 pg/ml), probably a reflection of the associated disease pathology of severe bone pain and pyrexia. In summary, this paper details clinical and laboratory investigations of a leukemia of a rare NK cell subset.

Bone Marrow↗
PubMed1995

Induction of interleukin-1 receptor antagonist (IL-1ra) following surgery is associated with major trauma.

Injury and trauma are major inducers of the acute-phase response. Among the major cytokine mediators of this response is interleukin-6, which is considered to be an early indicator of tissue damage following trauma. We have previously reported, in a group of children undergoing a single abdominal surgical procedure, the early induction of interleukin-1 receptor antagonist following the commencement of surgery. In the present study, we investigated the production of cytokines IL-1ra, IL-1 beta, and IL-6 in patients undergoing a range of surgical procedures to examine whether IL-1ra release is a general phenomenon or is restricted to certain categories of surgery. Peripheral blood mononuclear cells and polymorphonuclear leukocytes from patients were studied as a possible source of induced IL-1ra. IL-1ra and IL-6 were induced in 44 and 53 of the 73 patients, respectively. Induction of these cytokines was associated with major operative procedures of the abdomen and thorax and in hip replacement. Levels of these two cytokines varied widely within the different surgical categories. IL-1ra reached maximum levels before IL-6 in 18 patients and at the same time in 20 patients. IL-1 beta levels were induced in only 6 patients. Endotoxin levels were not detected in association with induction of IL-1ra. IL-1ra was not upregulated in peripheral blood mononuclear cells or polymorphonuclear leukocytes obtained from patients following surgery suggesting that these cells are not the source of plasma IL-1ra induced following trauma. These results provide new insights into the regulation of IL-1ra in vivo in humans. They show that IL-1ra can be induced as an early-response cytokine following major trauma in the absence of an infectious etiology.

Adolescent↗
PubMed1995

Abnormal innervation and altered nerve growth factor messenger ribonucleic acid expression in ureteropelvic junction obstruction.

The pathophysiology of ureteropelvic junction obstruction is unknown. Using specific antibodies, we studied specimens from 35 cases of ureteropelvic junction obstruction and 32 of normal ureteropelvic junction by immunohistochemistry using protein gene product 9.5 (a general neuronal marker), S100 (a supporting cell marker), synaptophysin (a neuromuscular junction marker) and nerve growth factor receptor. Nerve growth factor expression was examined at the messenger ribonucleic acid (mRNA) level using reverse transcription-polymerase chain reaction technique in 11 ureteropelvic junction obstruction specimens and 7 controls. The most striking finding was the marked reduction of protein gene product 9.5, synaptophysin and nerve growth factor receptor staining positive nerve fibers in the muscle layers of ureteropelvic junction obstruction compared to the normal ureteropelvic junction. Supporting nerve cell fibers (S100) were preserved in cases of ureteropelvic junction obstruction and normal ureteropelvic junction. A significantly less intense signal for nerve growth factor mRNA was found in the ureteropelvic junction obstruction specimens compared to normal ureteropelvic junction. These findings suggest that defective innervation may have an important role in the pathogenesis of ureteropelvic junction obstruction, and decreased nerve growth factor mRNA expression may be important in the etiology of ureteropelvic junction obstruction.

Base Sequence↗
PubMed1995

Signalling via CD28 of human naive neonatal T lymphocytes.

Accessory molecules play a crucial role in the development of the T cell response to antigenic challenge. We have examined the role of CD28 in modulating the 'naive' neonatal T cell response to anti-CD2-mediated activation. To compare the role of CD28, neonatal and adult T cells were stimulated with a pair of mitogenic anti-CD2 antibodies in the presence or absence of anti-CD28 MoAb. With anti-CD2 alone, neonatal T cells proliferated slightly but produced no detectable IL-2, whereas adult T cells proliferated vigorously, with significant IL-2 production. Costimulation with anti-CD28 MoAb greatly enhanced the proliferative response of neonatal T cells to levels equivalent to those of adult T cells, whereas adult T cells showed only slight increases. Although IL-2 secretion was increased in the presence of anti-CD28 MoAb, neonatal T cell IL-2 production remained lower than in adults. In contrast, enhancement of IL-2 mRNA expression in neonates was similar to adult levels. Anti-CD28 MoAb costimulation increased NF kappa B levels in neonates, albeit to levels lower than that of adults. The cellular mechanism governing the diminished proliferative response of neonatal T lymphocytes to anti-CD2 may therefore be due to decreased NF kappa B induction, reduced IL-2 mRNA expression and deficient IL-2 production. Although anti-CD28 MoAb costimulation enhances all of the above signals, NF kappa B and IL-2 levels remain lower than in adults, suggesting the need for further activation requirements in the neonate.

Adult↗
PubMed1995

Serum intercellular adhesion molecule (ICAM-1), a marker of renal scarring in infants with vesico-ureteric reflux.

OBJECTIVE: To determine if serum intercellular adhesion molecule (ICAM-1) levels correlate with renal scarring in children with vesico-ureteric reflux (VUR). PATIENTS AND METHODS: Serum ICAM-1 levels were measured in 81 children (29 boys and 52 girls, age range 2 months-13 years) with VUR using an enzyme-linked immunosorbent assay (ELISA) and compared with levels in a control group of 24 children (16 boys and eight girls, age range 2 days-13 years) with no urological abnormalities. RESULTS: The mean serum ICAM-1 level in the control group was 202 +/- 79 ng/mL (mean +/- 1 SD) compared with 347 +/- 96 ng/mL in children with VUR (P < 0.001). Fifteen of 26 children under 2 years of age demonstrated renal scarring while 18 of 44 children older than 2 years exhibited renal scarring. The mean serum ICAM-1 level in patients who were < 2 years of age and had renal scarring was 408 +/- ng/mL, significantly higher than in those who had no renal scarring (296 +/- 68 ng/mL, P < 0.01). In contrast, there was no difference in serum ICAM-1 levels in patients > 2 years of age with or with no renal scarring (353 +/- 87 and 325 +/- 91 ng/mL, respectively). CONCLUSION: Serum ICAM-1 levels are significantly higher in children with VUR and may represent a valuable marker of tubular damage in younger children with VUR.

Adolescent↗
PubMed1994

Interleukin-1 augments the diminished interleukin-2 mRNA expression and proliferative response of neonatal T lymphocytes to anti-CD2 antibodies.

Expression of IL-2 mRNA by unstimulated and stimulated purified T cells and mononuclear cells from adult and cord blood was investigated in an attempt to better understand the underlying defective neonatal host immune defense system. Using RNA dot-blot analysis, IL-2 mRNA expression in anti-CD2-stimulated neonatal T cells revealed significantly reduced levels when compared to adult T cells (P < 0.01). Purified neonatal T cells also showed a significantly reduced proliferative response to anti-CD2 antibodies (P < 0.01). Addition of IL-1 beta enhanced the hyporesponsiveness of neonatal T cells at both the level of proliferation and IL-2 mRNA expression. Unseparated mononuclear cells from adult and cord blood revealed similar IL-2 mRNA levels and proliferation when activated by anti-CD2 stimulation. The reduced IL-2 mRNA expression observed in neonatal T cells may explain, in part, the difference in host defense between the newborn and adult during states of increased demand such as infection.

Adult↗
PubMed1993

Characterisation of the local inflammatory response in appendicitis.

In this study we have characterised the local inflammatory response in acute suppurative appendicitis (S), focal appendicitis (F), and normal appendices (C). Enumeration of lymphocyte subpopulations, cells expressing IL-2 receptor, natural killer (NK) cells, monocytes and plasma cell isotypes and subclasses infiltrating the lamina propria was carried out on all specimens using immunoperoxidase staining procedures. Total T cells were significantly increased in both acute suppurative appendicitis and focal appendicitis compared with controls (p < 0.001). Cells infiltrating the lamina propria expressed IL-2 receptor in all appendiceal specimens but were significantly increased in both acute and focal appendicitis (p < 0.01). IgG and IgA plasma cell isotypes were significantly increased in all S and F appendiceal specimens (p < 0.001). Monocyte and NK cell numbers, however, were only increased in acute suppurative appendiceal specimens. The increased lymphocyte and plasma cell isotypes seen in focal appendicitis occurred throughout the entire organ even through the inflammatory focus was confined to only three to seven serial sections. These results clearly show a differential pattern of cellular infiltration in focal appendicitis from that seen in acute suppurative appendicitis. The selective lymphocyte and plasma cell nature of the cellular infiltrate in the lamina propria of focal appendicitis may reflect the presence of a specific immune response to an as yet unidentified luminal antigen as a possible cause of appendicitis.

Acute-Phase Reaction↗
PubMed1993

Inhibition of the adherence of Pseudomonas aeruginosa to epithelial cells by IgG subclass antibodies.

A beneficial role of the antibody response to Pseudomonas aeruginosa seen in cystic fibrosis (CF) patients has not been established. We investigated a possible role for these antibodies as inhibitors of the adherence of P. aeruginosa to mammalian cells. An adhesion model system was used, employing buccal epithelial cells in an enzyme-labelled immunoassay procedure on microtitration plates. Total levels of IgG, IgA, IgM and the four IgG subclasses were estimated in 11 CF patients and 10 healthy controls. Most of the CF patients demonstrated increased levels of all these immunoglobulin types. Sera from seven patients with elevated serum IgG were observed to cause greater inhibition of the adherence of P. aeruginosa to buccal cells than were the sera from four CF patients with low serum IgG and from ten healthy controls. Nevertheless, the levels of individual anti-P. aeruginosa IgG subclass antibodies varied amongst the patients and did not correlate with the degree of inhibition of bacterial adherence. Negative affinity chromatography was used to obtain antibody fractions enriched for IgG1, IgG2 or IgG4 and protein A-sepharose chromatography was used to isolate IgG3 antibodies from CF patients. The IgG1-, IgG2-, or IgG4-enriched fractions similarly inhibited the adherence of P. aeruginosa in the test system, whereas three of five IgG3-enriched fractions from CF patients had no greater effect on adhesion than did IgG from control individuals.

Adolescent↗
PubMed1993

Role of IgG subclass response to outer-membrane proteins in inhibiting adhesion of Pseudomonas aeruginosa to epithelial cells.

The IgG subclass response to the major outer-membrane proteins (OMPs) of Pseudomonas aeruginosa was investigated in 11 cystic fibrosis (CF) patients and 10 healthy controls. Inhibition of adhesion of P. aeruginosa to buccal epithelial cells by the IgG serum fractions from the CF patients has been established previously. The CF patients demonstrated marked heterogeneity in their individual IgG subclass response to pseudomonal OMPs. The predominant IgG1 and IgG4 responses were directed towards OMPs F, H2 and, with IgG1 only, to protein I. Proteins of 42 and 46 kDa primarily elicited an IgG2 response but some patients produced IgG4 antibodies. The IgG3 response varied from very weak in some patients to a strong reaction with proteins D2, E, G and I in others. The range of antigen-specific IgG subclass responses was similar in CF patients whose IgG fractions strongly inhibited the adherence of P. aeruginosa to epithelial cells and in those whose fractions gave only weak inhibition of adherence. There was no indication that an antibody response towards any particular OMP was implicated in the inhibition of bacterial adherence. Thus, the IgG subclass response to OMPs did not exert a significant effect on adherence when investigated in isolation, but may possibly play some role in combination with other processes.

Adult↗
PubMed1993

Early induction of IL-1 receptor antagonist (IL-1Ra) in infants and children undergoing surgery.

The cytokine response to injury or trauma is of interest in terms of both its mediation of the acute phase response and its possible relation to the immunological depression observed after major surgery. In this study, the production of cytokines IL-1 beta, tumour necrosis factor-alpha (TNF-alpha), IL-6 and the naturally occurring inhibitor of IL-1, IL-1Ra, have been investigated in infants and children undergoing Swenson's pull-through operation for Hirschsprung's disease. Samples of peripheral blood were taken before, during and after surgery for the measurement of cytokines. IL-1Ra levels increased significantly (P < 0.01) at 2 h after commencement of surgery, with maximal levels for individual patients being attained between 3 h and 5 h (range 7.6-67.9 ng/ml). The mean level of IL-1Ra was maximal (26.2 ng/ml) at 5 h and returned to baseline levels between 24 h and 72 h. There were no changes observed in the circulating levels of IL-1 beta in nine out of 11 patients following commencement of surgery. TNF-alpha levels did not increase in any of the patients studied. IL-6 levels increased significantly (P < 0.02) 3 h after commencement of surgery, reaching maximum concentrations at 24 h (range 20-670 pg/ml), with levels falling between 48 h and 72 h. This study demonstrates, in vivo, the independent induction of IL-1Ra without a concomitant increase of IL-1 beta levels after major surgery. It also shows that IL-1Ra is the earliest cytokine produced in response to surgical stress.

Child↗