Kunio Ohta

Age-Specific Differences in Outcomes After Out-of-Hospital Cardiac Arrests

OBJECTIVE: We assessed out-of-hospital cardiac arrests (OHCAs) for various pediatric age groups. METHODS: This prospective, population-based, observational study included all emergency medical service-treated OHCAs in Osaka, Japan, between 1999 and 2006 (excluding 2004). Patients were grouped as adults (>17 years), infants (<1 year), younger children (1–4 years), older children (5–12 years), and adolescents (13–17 years). The primary outcome measure was 1-month survival with favorable neurologic outcome. RESULTS: Of 950 pediatric OHCAs, resuscitations were attempted for 875 patients (92%; 347 infants, 203 younger children, 135 older children, and 190 adolescents). The overall incidence of nontraumatic pediatric OHCAs was 7.3 cases per 100 000 person-years, compared with 64.7 cases per 100 000 person-years for adults and 65.5 cases per 100 000 person-years for infants. Most infant OHCAs occurred in homes (93%) and were not witnessed (90%). Adolescent OHCAs often occurred outside the home (45%), were witnessed by bystanders (37%), and had shockable rhythms (18%). One-month survival was more common after nontraumatic pediatric OHCAs than adult OHCAs (8% [56 of 740 patients] vs 5% [1677 of 33 091 patients]; adjusted odds ratio: 2.26 [95% confidence interval: 1.63–3.13]). One-month survival with favorable neurologic outcome was more common among children than adults (3% [21 of 740 patients] vs 2% [648 of 33 091 patients]; adjusted odds ratio: 2.46 [95% confidence interval: 1.45–4.18]). Rates of 1-month survival with favorable neurologic outcome were 1% for infants, 2% for younger children, 2% for older children, and 11% for adolescents. CONCLUSION: Survival and favorable neurologic outcome at 1 month were more common after pediatric OHCAs than adult OHCAs.

Selective expansion of CD16highCCR2- subpopulation of circulating monocytes with preferential production of haem oxygenase (HO)-1 in response to acute inflammation

Monocytes are composed of two distinct subpopulations in the peripheral blood as determined by their surface antigen expressions, profiles of cytokine production and functional roles played in vivo. We attempted to delineate the unique functional roles played by a minor CD16highCCR2– subpopulation of circulating monocytes. They produced significant levels of interleukin (IL)‐6 and tumour necrosis factor (TNF)‐α, but very low levels of IL‐10 upon in vitro stimulation. Characteristic profiles of cytokine production were confirmed by stimulating purified subpopulations of monocytes after cell sorting. It was noteworthy that freshly isolated CD16highCCR2– monocyte subpopulations produced significant levels of haem oxygenase (HO)‐1, whereas the major CD16lowCCR2+ subpopulation produced little. These results were contrary to the generally accepted notion that the CD16highCCR2– monocyte subpopulation plays a predominantly proinflammatory role in vivo. The CD16highCCR2– subpopulation increased in Kawasaki disease and influenza virus infection. In accord with this, HO‐1 mRNA expression by mononuclear cells was significantly increased in these illnesses. These results indicate that CD16highCCR2– subpopulations are of a distinct lineage from CD16lowCCR2+ monocytes. More importantly, they may represent a monocyte subpopulation with a unique functional role to regulate inflammation by producing HO‐1 in steady state in vivo.

Increasing Prevalence of Ampicillin- Resistant, Non-Beta-Lactamase-Producing Strains of Haemophilus influenzae in Children in Japan

Among Haemophilus influenzae isolated from children with respiratory tract infections, the evolution of ampicillin resistance was investigated during 1996 and 1997 in Japan. β-Lactamase production was assessed and minimum inhibitory concentrations (MICs) of eight antimicrobial agents were determined using a broth microdilution method in Mueller-Hinton-lysed horse blood medium. Of 74 H. influenzae, 11 strains (14.9%) produce β-lactamase and were thus highly resistant to ampicillin (MIC of >4.0 µg/ ml). In addition, moderate resistance to ampicillin, defined as an MIC of ≧1.0 µg/ml, was noted in 44.4% of all β-lactamase-negative isolates. These β-lactamase-negative ampicillin-resistant (BLNAR) organisms were resistant to other cephalosporins such as cefpodoxime and cefdinir, while β-lactamase-producing strains were susceptible to them. Cefditoren, cefteram, and minocycline were active against all strains studied, whereas cefaclor and clarithromycin were inactive against all H. influenzae isolates in this study. Results indicate that BLNAR strains have emerged among children with respiratory tract infections in Japan.

Expression of CD45R0 (UCHL1) by CD4^+ and CD8^+ T cells as a sign of in vivo activation in infectious mononucleosis

CD4SR0 (UCHL1), a member of leucocyte common antigen family, is expressed largely on previously activated or memory T cells. We examined CD45R0 expression of T cell subpopulations in patients with Epstein‐Barr virus (EBV) induced infectious mononucleosis (IMN) as a sign of in vivo activation. Consistent with the notion that activated CD8+ T cells expand in acute IMN, the majority of CD8+ T cells in patients with acute IMN expressed CD45R0 to the similar extent to HLA‐DR expression. Most CD4+ T cells in these patients also demonstrated marked expression of CD45R0 as well as HLA‐DR antigens, compared with age‐matched controls. Expression of CD45R0 by CD4+ T cells in patients with acute IMN was more notable than their HLA‐DR expression. While predominant CD8+ T cells resulted in decreased percentages of CD4+ T cells, CD4+ T cells expressing CD4SR0 were shown to be significantly elevated in absolute number. The results suggest that both CD4+ and CD8+ T cells may be activated by stimulation with EBV infection. The appearance of two T cell subpopulations expressing CD4SR0 in acute IMN implies their immunoregulatory roles in the control of EBV‐infected cells.

Oligoclonal expansion of circulating and tissue-infiltrating CD8+ T Cells with killer/effector phenotypes in juvenile dermatomyositis syndrome

Although triggering by infectious agents and abnormal immune responses may play some role in the pathogenesis of juvenile dermatomyositis syndrome (JDMS), the precise mechanism of muscle destruction and vascular damage is largely unknown. In this study, we tried to elucidate the role of cytotoxic T cells in two patients with JDMS, who were diagnosed based on the characteristic symptoms, laboratory data, MRI findings and electromyographic patterns. Peripheral blood T cell phenotypes were determined by flow cytometry, using mAbs against specific T cell receptor (TCR) Vβs. Complementarity‐determining region3 (CDR3) size analysis was performed by gene scanning of CDR3 polymerase chain reaction (PCR) amplification products specific for each Vβ. Subsequently, CDR3 nucleotide sequences were obtained after cloning of the predominant products. The distribution of lymphocytes infiltrating the muscle tissue was analysed by immunohistochemistry. In both patients examined, a unique combination of TCR Vβ repertoires was increased within the CD8+ T cells. These subpopulations expressed a characteristic phenotype, indicating that they are memory/effector T cells with killer functions. At the same time, immunohistological and molecular biological examinations of the biopsied muscle samples revealed that identical CD8+ T cell clones with identical phenotypes/TCR Vβ infiltrated within the inflammatory tissue, in particular around vessels. These findings indicate that oligoclonal expansion of CD8+ T cells plays a central role in the pathogenesis of muscle injury in the juvenile form of dermatomyositis syndrome and may provide a useful clinical parameter of disease activity and responsiveness to anti‐inflammatory therapy.

Public access defibrillation improved the outcome after out-of-hospital cardiac arrest in school-age children: a nationwide, population-based, Utstein registry study in Japan.

Aims The purpose of this study was to determine whether implementation of public access defibrillation (PAD) improves the outcome after out-of-hospital cardiac arrest (OHCA) in school-age children at national level. Methods and results We conducted a prospective, nationwide, population-based Japanese Utstein registry study of consecutive OHCA cases in elementary and middle school children (7–15 years of age) who had a bystander-witnessed arrest of presumed cardiac origin during 2005–09 and received pre-hospital resuscitation by emergency responders. The primary endpoint was a favourable neurological outcome 1 month after an arrest. Among 230 eligible patients enrolled, 128 had ventricular fibrillation (VF) as an initial rhythm. Among these 128 patients, 29 (23%) children received a first shock by a bystander. Among these 29 patients, the proportion of the favourable neurological outcome after OHCA was 55%. During the study period, the proportion of patients initially shocked by a bystander among eligible patients increased from 2 to 21% (P = 0.002 for trend). The proportion of patients with a favourable neurological outcome after OHCA increased from 12 to 36% overall (P = 0.006). The collapse to defibrillation time was shorter in bystander-initiated defibrillation when compared with defibrillation by emergency responders (3.3 ± 3.7 vs. 12.9 ± 5.8 min, P < 0.001), and was independently associated with a favourable neurological outcome after OHCA [P = 0.03, odds ratio (OR) per 1 min increase, 0.90 (95% confidence interval 0.82–0.99)]. A non-family members witness was independently associated with VF as the initial rhythm [P < 0.001, OR 4.03 (2.08–7.80)]. Conclusion Implementation of PAD improved the outcome after OHCA in school-age children at national level in Japan.

Increased levels of urinary interleukin-6 in Kawasaki disease

Kawasaki disease (KD) often presents with abnormal urinary findings, such as aseptic pyuria, mild proteinuria and microscopic haematuria. In this study, we measured urinary interleukin-6 (IL-6) by a sensitive sandwich ELISA assay using mouse monoclonal antibodies against recombinant IL-6 to elucidate the role of IL-6 in the pathogenesis of renal lesions in KD. Serum IL-6 levels were increased in acute KD as well as in febrile controls. Importantly, urinary IL-6 levels were consistently elevated in patients with acute KD, but much lower in febrile controls. Urinary IL-6 levels returned steadily to normal during the convalescent phase. In addition to IL-6, urinary levels ofN-acetyl-β-d-glucosaminidase (NAG) and β2-microglobulin (β2-mg) were also elevated during the acute phase of this disease. Eosinophils and macrophages were identifiable in urinary sediments from these patients. The increased levels of urinary IL-6 in combination with increased NAG and β2-mg seemed to suggest the presence of certain renal parenchymal lesions with cellular infiltration during the acute phase of the disease. IL-6 may serve as clinically useful parameter for the detection and monitoring of the renal involvement in KD.

Paradoxical enhancement of oxidative cell injury by overexpression of heme oxygenase-1 in an anchorage-dependent cell ECV304.

There has been increasing evidence suggesting the potent anti‐inflammatory roles of heme oxygenase‐1 (HO‐1) in protecting renal tubular epithelial cells, vascular endothelial cells, and circulating monocytes. Based on these findings, novel therapeutic interventions have been proposed to control the expression of endothelial HO‐1 levels to ameliorate various vascular diseases. We evaluated the effect of HO‐1 gene transfer into an anchorage‐dependent cell, ECV304. Effect of HO‐1 production on the cell injury induced by hydrogen peroxide was evaluated after hemin stimulation and after HO‐1 gene transfection. Morphological changes and the induction of various anti‐apoptotic proteins were examined at the same time. Levels of HO‐1 expression were variable in different clones of HO‐1‐transfected ECV304 cells. Among these, the clones with moderate levels of HO‐1 expression were significantly more resistant to oxidative stress. In contrast, those with the highest levels of HO‐1 exhibited paradoxically enhanced susceptibility to oxidative injury. Interestingly, the cell survival after oxidative stress was in parallel with the levels of Bcl‐2 expression and of fibronectin receptor, α5 integrin. It is suggested from these results, that excessive HO‐1 not only leads to enhanced cell injury, but also prolongs the repair process of the injured endothelial tissue. However, HO‐1 reduces the oxidative cell injury and protects the endothelial cells, if its expression is appropriately controlled.

Phosphodiesterase Inhibitors Suppress Lactobacillus casei Cell-Wall-Induced NF-κB and MAPK Activations and Cell Proliferation through Protein Kinase A—or Exchange Protein Activated by cAMP-Dependent Signal Pathway

Specific strains of Lactobacillus have been found to be beneficial in treating some types of diarrhea and vaginosis. However, a high mortality rate results from underlying immunosuppressive conditions in patients with Lactobacillus casei bacteremia. Cyclic AMP (cAMP) is a small second messenger molecule that mediates signal transduction. The onset and progression of inflammatory responses are sensitive to changes in steady-state cAMP levels. L. casei cell wall extract (LCWE) develops arteritis in mice through Toll-like receptor-2 signaling. The purpose of this study was to investigate whether intracellular cAMP affects LCWE-induced pathological signaling. LCWE was shown to induce phosphorylation of the nuclear factor κB (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways and cell proliferation in mice fibroblast cells. Theophylline and phosphodiesterase inhibitor increased intracellular cAMP and inhibited LCWE-induced cell proliferation as well as phosphorylation of NF-κB and MAPK. Protein kinase A inhibitor H89 prevented cAMP-induced MAPK inhibition, but not cAMP-induced NF-κB inhibition. An exchange protein activated by cAMP (Epac) agonist inhibited NF-κB activation but not MAPK activation. These results indicate that an increase in intracellular cAMP prevents LCWE induction of pathological signaling pathways dependent on PKA and Epac signaling.

Development of Vascular Biology over the past 10 Years: Heme Oxygenase-1 in Cardiovascular Homeostasis

The study of vascular biology has provided strong evidence for the role that free radical attack plays in the pathogenesis of cardiovascular diseases. The endothelial cell (EC) dysfunction that results from exposure to oxidative stresses, such as oxidized LDL, influences vascular cell gene expression, promoting smooth muscle cell (SMC) mitogenesis and apoptosis. These factors also play an important role in atherogenesis, which is attenuated by antioxidants. Thus, antioxidants are important to understanding the pathophysiology of cardiovascular diseases and to constructing an effective treatment strategy for these patients. Over the last decade, there has been a tremendous interest in the biology of heme oxygenase-1 (HO-1), which exhibits antioxidant effects in various forms of tissue injury. Moreover, the reaction is also the major source of carbon dioxide (CO) in the body, which is a physiologically important gaseous vasodilator that inhibits SMC proliferation. Thus, HO-1–derived products provide various mechanisms to maintain cardiovascular homeostasis. We review recent work on the cellular and molecular biological aspects of the HO/CO system in vascular pathophysiology.