Analysis of Age, Sex, Lack of Response to Intravenous Immunoglobulin, and Development of Coronary Artery Abnormalities in Children With Kawasaki Disease in Japan

IMPORTANCE

Initial intravenous immunoglobulin (IVIG)-refractory status and prolonged fever are established risk factors for the development of coronary artery abnormalities (CAAs) among patients with acute-phase Kawasaki disease (KD). However, whether different risk factors exist for initial unresponsiveness to IVIG and CAA development remains unclear.

OBJECTIVE

To evaluate whether different risk factors exist for initial unresponsiveness to IVIG and CAA development among patients with KD (stratified by age at disease onset).

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study included a consecutive sample of 2414 patients from a database of patients with KD from October 1, 1999, to September 30, 2019. The data were based on annual surveys (response rate, 100%) using hospital medical records across Wakayama Prefecture, Japan. Data were analyzed from March 6 to March 26, 2022.

EXPOSURES

The patient's age and diagnosis of KD by board-certified pediatricians using the criteria established by the Japan KD Research Committee.

MAIN OUTCOMES AND MEASURES

Initial unresponsiveness to IVIG, defined as treatment with optional or advanced therapies, and development of CAAs. Echocardiograms performed 1 month after KD onset using the Japanese Ministry of Health criteria evaluated the presence or absence of CAAs. Odds ratios (ORs) with 95% CIs of patient age at KD onset for unresponsiveness to IVIG and developing CAAs were calculated using multivariable logistic regression models.

RESULTS

A total of 2414 patients (1403 male patients [58.1%]; median age at onset of KD, 25 months [range, 1-212 months]) were included in the study: 550 younger than 12 months, 1342 aged 12 to 47 months, and 522 older than 47 months. A total of 535 patients (22.2%) received optional or advanced treatment and 68 patients (2.8%) developed CAAs 1 month after disease onset. The sex-adjusted OR among patients younger than 12 months for unresponsiveness to IVIG was 0.77 (95% CI, 0.59-0.99) and for development of CAAs was 1.94 (95% CI, 1.07-3.52); among those older than 47 months, the OR for unresponsiveness to IVIG was 1.32 (95% CI, 1.05-1.67) and for development of CAAs was 2.47 (95% CI, 1.39-4.39). After adjusting for IVIG administration, ORs among boys older than 47 months for unresponsiveness to IVIG was 1.14 (95% CI, 0.84-1.56) and for development of CAAs was 2.15 (95% CI, 1.08-4.30); among girls younger than 12 months, the OR for unresponsiveness to IVIG was 1.02 (95% CI, 0.65-1.60) and for development of CAAs was 3.79 (95% CI, 1.21-11.90).

CONCLUSIONS AND RELEVANCE

The results of this study suggest that risks of unresponsiveness to IVIG and the development of CAAs differ between infants with KD and older patients with KD. Residual risk factors for KD-related CAAs other than initial unresponsiveness to IVIG should be addressed, particularly in infants.

Z-score is a possible predictor of the risk of coronary artery lesion development in patients with Kawasaki disease in Japan

Risk factors for coronary artery lesion (CAL) development in patients with Kawasaki disease (KD) include male sex, age < 12 months, intravenous immunoglobulin (IVIG) resistance, and delayed diagnosis.. We aimed to explore the relationship between CAL development and Z-score. We enrolled 281 patients with KD who were treated with our protocol. Echocardiography was performed in three phases: pre-treatment (P1), post-treatment (P2), and 4 weeks after onset (P3). The highest Z-score of the right, left main, left anterior descending, and left circumflex coronary arteries was expressed as Zmax at each phase. P3-Zmax ≥ 2.5 represented CAL development. Clinical parameters, such as laboratory data and Z-scores, were retrospectively compared between patients with and without CAL development. Sixty-seven patients (23.8%) showed a P1-Zmax ≥ 2.0, and CAL development occurred in 21 patients (7.5%). Independent risk factors associated with CAL development were P1-Zmax, a ΔZmax (P2-Zmax - P1-Zmax) ≥ 1, male sex, < 12 months of age, and resistant to the first intravenous immunoglobulin (IVIG) administration (adjusted odds ratio [95% confidence interval]: 198 [1.01-3.92], 4.04 [1.11-14.7], 6.62 [1.33-33.04], 4.71 [1.51-14.68], 5.26 [1.62-17.13], respectively). Using receiver operating characteristic curve analysis, a P1-Zmax ≥ 1.43 detected CAL development with an area under the curve of 0.64 (sensitivity = 81.0%; specificity = 48.1%).Conclusion: Our results suggest that P1-Zmax and a ΔZmax (P2-Zmax - P1-Zmax) ≥ 1 may predict CAL development. What is Known: • KD is an acute vasculitis predominantly affecting the coronary artery of young children. • Although P1 Z-max ≥ 2.0 has been a predictor of CAL development, it has not yet been shown in Japan. What is New: • P1-Zmax and a ΔZmax ≥ 1 are presumably associated with CAL development. • In the ROC curve analysis, P1-Zmax ≥ 1.43 detected CAL development, a sensitivity (81%) and a specificity (48%). We need to consider intensified initial therapy for patients with these risk factors.

Intimal thickening and disruption of the media occur in the arterial walls of coronary arteries not associated with coronary arterial aneurysms in patients with Kawasaki disease

Background

Coronary artery aneurysm (CAA) is an important complication of Kawasaki disease (KD) that is associated with arterial structure damage. However, few studies have examined structural changes in coronary arteries that are not associated with CAA.

Methods

We examined coronary arteries in KD patients with CAAs who underwent follow-up coronary angiography (CAG) and optical coherence tomography (OCT). Coronary arterial branches with no abnormal findings during the most recent CAG were classified into two groups. Arteries with an acute-phase CAA that later regressed were classified as group R; arteries with no abnormal findings on either acute or convalescent phase CAG were classified as group N. Coronary arterial wall structural changes were compared between groups using OCT.

Results

Fifty-seven coronary arterial branches in 23 patients were evaluated by OCT. Thirty-six branches showed no abnormality during the most recent CAG. Both groups R and N comprised 18 branches. Maximum intimal thicknesses in groups R and N were 475 and 355 µm, respectively (p = 0.007). The incidences of media disruption were 100% and 67%, respectively (p = 0.02). Calcification, macrophage accumulation, and thrombus were not found in either group.

Conclusions

Intimal thickening and disruption of the media occur in coronary arteries with acute phase CAAs that later regress in the convalescent phase, as well as in arteries with normal CAG findings in the acute and convalescent phases.

Seasonal Variation in Epidemiology of Kawasaki Disease-Related Coronary Artery Abnormalities in Japan, 1999-2017

BACKGROUND

Epidemiological studies show a U-shaped tendency in Kawasaki disease (KD)-related coronary artery abnormalities (CAAs) across age categories. Since studies suggest seasonal variations in KD onset, this study aimed to clarify the epidemiologic features of CAAs, considering the seasons of KD-occurrence.

METHODS

We analyzed 2,106 (males = 1,215, females = 891) consecutive KD cases from October 1999 through September 2017 using our electronic database of annual surveys, targeting all hospitals with pediatric departments across Wakayama, Japan. The primary outcome was the presence/absence of CAAs measured by echocardiography 1 month after KD onset. Odds ratios (ORs) and 95% confidence intervals (CIs) of combined patient age and sex for CAAs were calculated using logistic regression models adjusted for four seasons.

RESULTS

The median age was 25 (range, 1-212) months. The proportion of males decreased with increasing age. The youngest age group (<6 months) showed an inverse summer/autumn to winter/spring ratio (>1.0) in KD-occurrence. CAAs were observed in 2.8% of cases (males = 3.4%, females = 2.1%), which significantly lessened in summer than in other seasons. Moreover, 50% (n = 4/8) of cases with giant aneurysms experienced KD in autumn. Adjusted ORs for CAAs among males aged ≥60 months (3.0; 95%, CI 1.2-7.5) and females aged <6 months (3.6; 95%, CI 1.1-11.8) were significantly higher than those among males aged 12-35 months.

CONCLUSIONS

Cumulative 18-year data of consecutive KD cases from one area suggest the influence of interactions between patient age and sex on the development of KD-related CAAs. The season of KD-occurrence may reflect the diversity of agents.

[Cyclosporin A treatment for refractory Kawasaki disease]

The association between functional polymorphism of inositol 1,4,5-trisphosphate 3- kinase-C(ITPKC) and susceptibility to Kawasaki disease(KD) and formation of coronary arterial lesions was reported in 2008. Since ITPKC acts as a negative regulator of T-cell activation, activated T cells may play a pivotal role in the pathogenesis of KD. Cyclosporin A(CsA), which potently suppresses the activity of T cells through negative regulation of the nuclear factor of activated T cells(NFAT) pathway, may be a promising candidate for the treatment of refractory KD. In this review, we summarize the results of our clinical trials of CsA for refractory KD, the changes in the levels of cytokines before and after CsA treatment, and the future direction of CsA treatment for refractory KD.

Epidemiologic features and prognostic factors of coronary artery lesions associated with Kawasaki disease based on a 13-year cohort of consecutive cases identified by complete enumeration surveys in Wakayama, Japan

Background

To clarify the contribution of patient age to the development of coronary artery lesions (CALs) associated with Kawasaki disease (KD), epidemiologic features and prognostic factors were investigated using hospital-based complete enumeration surveys in a specific area.

Methods

Consecutive KD cases identified between October 1999 and September 2012 in Wakayama Prefecture, Japan, were analyzed. The primary outcome measure was the presence/absence of CALs (giant aneurysm, mid- or small-sized aneurysm, and dilatation) on echocardiography 1 month after disease onset. Demographics and medical treatment factors were compared between the patients with and without CALs. Odds ratios (ORs) and 95% confidence intervals (CIs) of explanatory variables (age, gender, and factors related to high-dose intravenous immunoglobulin treatment) for the development of CALs were determined.

Results

The median age of the 1415 patients (796 males, 619 females) was 25 months after excluding 2 children of foreign residents; 2.2% of the patients had a past history of KD, and 1.8% showed incomplete presentation. CALs were observed in 3.3% (4.0% of males, 2.3% of females; P = 0.080). The ORs of CALs among patients <11 months old (3.0, 95% CI 1.4–6.6) and those >48 months old (3.1, 95% CI 1.5–6.6) were significantly higher than values in 11- to 48-month-olds.

Conclusions

The effect of patient age on the development of CALs was found to be U-shaped, with the bottom at ages 11 to 48 months. This finding was based on a 13-year cohort of consecutive KD cases in a specific area with little selection bias and is consistent with previously reported results.

Marker of T-cell activation is elevated in refractory Kawasaki disease

BACKGROUND

The aim of this study was to investigate whether T-cell activation is involved in the pathogenesis of Kawasaki disease (KD) resistant to intravenous immunoglobulin (IVIG) treatment.

METHODS

Serum samples were obtained from 27 patients who fulfilled the diagnostic criteria for KD. These 27 patients were divided into three groups according to their responses to IVIG: Group A, nine patients who showed no response to either initial IVIG or additional IVIG; Group B, six patients who did not respond to initial IVIG but did respond to additional IVIG; Group C, 12 patients who responded to initial IVIG. Serum samples were obtained before and after initial IVIG. Using a commercial chemiluminescence enzyme immunoassay, we examined the serum levels of two cytokines related to T-cell activation and the severity of inflammation: soluble interleukin-2 receptor and interleukin-6.

RESULTS

There were no significant differences in the serum levels of the two cytokines before initial IVIG among the three groups, but significant intergroup differences were evident after initial IVIG in the serum levels of soluble interleukin-2 receptor (P < 0.01, Group A > C) and interleukin-6 (P < 0.01, Group A > B > C).

CONCLUSIONS

Our results show that marker of T-cell activation is elevated most markedly in KD patients resistant to both initial and additional IVIG, and suggest that T cells may be activated in refractory KD.

Common variants in CASP3 confer susceptibility to Kawasaki disease

Kawasaki disease (KD; OMIM 611775) is an acute vasculitis syndrome which predominantly affects small- and medium-sized arteries of infants and children. Epidemiological data suggest that host genetics underlie the disease pathogenesis. Here we report that multiple variants in the caspase-3 gene (CASP3) that are in linkage disequilibrium confer susceptibility to KD in both Japanese and US subjects of European ancestry. We found that a G to A substitution of one commonly associated SNP located in the 5' untranslated region of CASP3 (rs72689236; P = 4.2 x 10(-8) in the Japanese and P = 3.7 x 10(-3) in the European Americans) abolished binding of nuclear factor of activated T cells to the DNA sequence surrounding the SNP. Our findings suggest that altered CASP3 expression in immune effecter cells influences susceptibility to KD.

Small temperature variations alter edaravone-induced neuroprotection of cortical cultures exposed to prolonged hypoxic episodes

BACKGROUND

Edaravone, a free radical scavenger, has been shown to be neuroprotective in vivo and in vitro. However, the impact of small temperature variations on its neuroprotective actions remains unknown.

METHODS

We examined the degree of neuroprotection conferred by various concentrations of edaravone on cortical cultures exposed to prolonged hypoxia (24 h) under three conditions: mild hypothermia (32 degrees C), normothermia (37 degrees C), and mild hyperthermia (39 degrees C). The survival of cortical neurones from E16 Wistar rats (SR) was evaluated using photomicrographs taken before and after exposure to hypoxia.

RESULTS

The mean survival of neurones exposed to hypoxia at normothermia was 14.7 (sem 1.8)%. The addition of 50 microM edaravone significantly improved the mean survival to 40.5 (4.7)%. This improvement was noted at higher doses of edaravone (5 microM < or =) but not at lower doses (< or =500 nM). With mild hypothermia and prolonged hypoxia without edaravone, neuroprotection was significantly improved with a mean survival of 63.0 (5.2)%. This neuroprotective effect was not enhanced with the addition of edaravone, even at the highest dose. Hypoxia-induced neurotoxicity was aggravated by mild hyperthermia as reflected by a mean survival of 9.1 (2.1)%. However, higher concentrations of edaravone inhibited the deleterious effect of mild hyperthermia, thereby demonstrating a significant neuroprotective effect. The survival of neurones subjected to both hyperthermia and edaravone was the same as that of neurones exposed to normothermia and edaravone.

CONCLUSIONS

Temperature is a potential factor in determining whether edaravone confers a neuroprotective effect when applied during prolonged hypoxic insults.

Detection of multiple superantigen genes in stools of patients with Kawasaki disease

OBJECTIVES

To investigate whether superantigens (SAgs) are involved in the development of Kawasaki disease (KD) by examining SAg genes in the stool of patients with KD.

STUDY DESIGN

Stool specimens were obtained from 60 patients with KD and 62 age-matched children (36 children with acute illness and 26 healthy children). Total DNA was extracted from these stool samples. Using polymerase chain reaction, we examined genes of 5 SAgs: streptococcal pyrogenic exotoxin-A (SPE-A), SPE-C, SPE-G, SPE-J, and toxic shock syndrome toxin-1.

RESULTS

At least 1 of the 5 SAg genes was detected in 42 (70%) specimens from patients with KD, 14 (38.9%) from the febrile group, and 7 (26.9%) from the healthy group. The detection rate between subjects with and without KD was of at least 1 of the 5 SAg genes (P < .001), and more than 2 SAg genes were significantly different (P = .002).

CONCLUSIONS

SAg may be involved in the development of KD; data suggest that multiple SAgs may trigger KD.

Ketamine and thiopental sodium: individual and combined neuroprotective effects on cortical cultures exposed to NMDA or nitric oxide

BACKGROUND

An N-methyl-D-aspartate (NMDA) blocker, ketamine, has been shown to be neuroprotective both in vivo and in vitro. However, ketamine is not commonly recommended for use in patients suffering from cerebral ischaemia because of its adverse neurological effects. We hypothesized that combined administration of ketamine and thiopental sodium (TPS) would be highly effective in protecting cerebral cortical neurones from ischaemia, with possibly reduced dosages.

METHODS

We examined the degree of neuroprotection provided by various concentrations of ketamine and TPS, alone and in combination, in cortical cultures exposed to NMDA or a nitric oxide-releasing compound (NOC-5) for 24 h. The survival rate (SR) of E16 Wistar rat cortical neurones was evaluated using photomicrographs before and after exposure to these compounds.

RESULTS

The SRs of cortical neurones exposed to 30 microM NMDA or NOC-5 were 15.0 (3.8)%, 12.8 (3.1)%, respectively. Higher doses (5, 10 and 50 microM) but not lower doses (<1 microM) of ketamine improved SRs [57.9 (2.2)%, 61.1 (5.4)%, 76.7 (3.0)%, respectively] against NMDA but not NOC. Enhanced survival was observed with combined administration of 5 or 10 microM ketamine and 50 microM TPS [SR 71.3 (4.8)%, 74.7 (3.7)%, respectively, P<0.05 if ketamine alone, P<0.01 if TPS alone], against NMDA-induced neurotoxicity in vitro. Only the highest dose of TPS (50 microM) improved survival after NOC exposure. This neuroprotection was not influenced by ketamine.

CONCLUSIONS

These data indicate that a low, clinically relevant dose of ketamine offer significant neuroprotection during prolonged exposure to NMDA but not to NOC. Combinations of reduced doses of ketamine and TPS exhibited enhanced neuroprotection against NMDA-induced neurotoxicity. Hence, combinations of these two common i.v. anaesthetics agents could be developed to protect the brain from ischaemia.

[Effects of octreotide acetate on intractable chylothorax after surgery for congenital heart diseases]

We experienced 2 infants in whom octreotide acetate was effective on intractable chylothorax after surgery for congenital heart diseases. They were 8- and 5-month-old. They were diagnosed as having corrected transposition of the great arteries (TGA) and tetralogy of Fallot respectively, and underwent bidirectional Glenn anastomosis and right modified Blalock Taussig shunt. Chylothorax was revealed on the 11th and the 1st postoperative day, and was not improved by any conventional therapy in either case. Then octreotide acetate was infused continuously with 0.1-0.6 micorg/kg/hour for 24 and 7 days. Chylothorax disappeared completely without any complications such as disturbance of blood sugar level or growth retardation. Octreotide acetate was effective and safe even in infants in intractable chylothorax after surgery for congenital heart diseases, as long as used for short period.

[Effects of additional pulmonary blood flow after bidirectional Glenn procedure]

Thirteen cases of functional single ventricle who had undergone bidirectional Glenn procedure were divided into 2 groups according to presence (5) or absence (8) of additional pulmonary blood flow. Additional flow was preserved in cases with relatively small pulmonary artery index (PA index), and their sources were antegrade pulmonary blood flow (2), and Blalock-Taussig (BT) shunt (3). In the control group, PA index was reduced to about 70% of the preoperative value, while in the additional group, pulmonary artery growth was recognized without significant elevation of mean pulmonary artery pressure. However, atrioventricular valve regurgitation progressed and systemic ventricular volume did not decrease after Glenn in the additional group. Therefore special consideration for the timing of Fontan procedure is mandatory.

Water retention in the acute phase of Kawasaki disease: relationship between oedema and the development of coronary arterial lesions

Despite intravenous immunoglobulin therapy, a certain percentage of patients with Kawasaki disease (KD) still develop coronary arterial lesions (CAL). In an effort to find new combined therapies to reduce the incidence of CAL, we focused on the oedema which can be an important sign of the increased vascular permeability in KD. A total of 127 patients with KD were included in the retrospective study. Serial weekly changes in serum sodium and albumin levels from the 1st to the 4th week of illness were examined. In addition, the maximum rate of increase in body weight from admission to the 14th day of illness was evaluated. Serum sodium levels (mEq/l) in only the 2nd week of illness were significantly lower in patients with CAL than in those without CAL (mean +/- SD, 135.5+/-4.5 versus 138.0+/-2.4, P<0.05). Serum albumin levels in all 4 weeks were significantly lower in patients with CAL than in those without CAL ( P<0.001). The maximum rate (%) of increase in body weight from admission to the 14th day of illness was significantly higher in patients with CAL than in those without CAL (ranges and median values, 0-12.3 (7.0) versus 0-10.3 (3.2), P<0.001).

CONCLUSION

these results suggest that water retention in the acute phase of Kawasaki disease may be a risk factor for CAL, and water intake of both infusion and oral intake should be kept to a minimum in order to avoid progressive oedema.

Detection of auto-antibodies against a 70 kDa protein derived from vascular smooth muscle cells in patients with Kawasaki disease

The aetiology and pathogenesis of Kawasaki disease (KD) remain unknown. To investigate the pathogenesis of vasculitis in KD, we tested for the presence of auto-antibodies against a component of vascular smooth muscle cells in the sera of patients with KD. Sera from 48 patients with KD, as well as sera from 14 sick children and from 22 healthy children, were examined for reactivity to both coronary arterial wall tissues and cultured smooth muscle cells (CSMC) derived from human coronary artery, using immunofluorescence and Western immunoblot assay techniques. Sera from 16 of 48 patients with KD gave positive immunoreactions to the vascular walls of coronary artery with fluorescein isothiocyanate-labelled rabbit anti-human IgA antibodies. In Western immunoblot assays, the sera from 15 of 34 and 10 of 31 patients with KD showed positive reactions against a 70 kDa protein from CSMC with IgA and IgM antibodies, respectively. Positive immunoreactivity of sera from patients with KD, determined either by immunofluorescence studies or by Western immunoblotting, was detected more frequently ( P<0.05) and more intensely ( P<0.005) in patients with coronary arterial lesions (CAL) than in those without CAL. Positive immunoreactivity of sera was prominent before intravenous immunoglobulin therapy and decreased dramatically thereafter.

CONCLUSION

these data suggest that auto-antibodies against a 70 kDa protein from vascular smooth muscle cells may cause coronary arteritis and systemic vasculitis in KD.

Neuroprotective effect of hypothermia at defined intraischemic time courses in cortical cultures

Many experimental and clinical studies have shown that hypothermia confers cerebroprotective benefits against ischemic insults. Because of the many conflicting reports on hypothermic neuroprotection, we undertook this cellular study to identify the optimal temperature or a range of temperatures for maximal neuroprotection at different times (6-24 hr) during ischemic insults. Cultured Wistar rat cortical neurons were exposed to oxygen deprivation at defined times and temperatures (37 degrees C normothermia, 32 degrees C mild hypothermia, 27 degrees C moderate hypothermia, 22 degrees C deep hypothermia, and 17 degrees C profound hypothermia). The survival rate of neurons was evaluated by assessing viable neurons on photomicrographs. The normothermic group demonstrated a significantly lower survival rate of cultured neurons (6 hr, 80.3% +/- 2.7%; 12 hr, 56.1% +/- 2.1%; 18 hr, 34.2% +/- 1%; 24 hr, 18.1% +/- 2.2%) compared to hypothermic groups (P < 0.001). The survival rate for the profound hypothermic group was significantly reduced (P < 0.01) compared to other hypothermic groups (at 17 degrees C: 12 hr, 85.9% +/- 2.5%, 18 hr, 74.7% +/- 3.7%, 24 hr, 58.7% +/- 2.7%). Almost equal survival rates were observed among mild, moderate, and deep hypothermic groups following <18 hr exposure to hypoxia, but the deep hypothermic group showed a significantly higher survival rate (84.1% +/- 1.6%; P < 0.001) when subjected to hypoxia for 24 hr. In conclusion, hypothermia offers marked neuroprotection against hypoxia, but attenuation of neuronal cell death was less with profound hypothermia compared to mild, moderate, and deep hypothermia. Deep hypothermia affords maximal protection of neurons compared to mild and moderate hypothermia during long-lasting hypoxia (>18 hr).

The effects of propofol on NMDA- or nitric oxide-mediated neurotoxicity in vitro

Acute brain ischemia causes neurotoxic cascades including NMDA receptors and NO. Propofol, an i.v. anesthetic, is thought to have a neuroprotective effect. We investigated the influence of propofol on NMDA/NO neurotoxicity using Shibuta's established model of primary brain cultures. Cortical neurons prepared from E16 were used after 13-14 days in culture. The neurons were exposed to various concentrations of propofol with NMDA or NO-donor. The survival rates of neurons exposed to 30 microM NMDA with or without 300 microM propofol were 12.1 +/- 2.2% and 11.9 +/- 2.2%, respectively. The survival rates exposed to 30 microM NO-donor with or without 300 microM propofol were 11.2 +/- 4.2% and 14.0 +/- 3.9%, respectively. These results suggest that neuroprotective effect of propofol is limited and propofol does not offer advantages over thiopental against NMDA/NO-induced cytotoxicity.

The influence of the timing of administration of thiopentone sodium on nitric oxide-mediated neurotoxicity in vitro

Thiopentone sodium is a highly useful pharmacological agent that provides a neuroprotection against cerebral ischaemia. Since not all patients can receive thiopentone sodium before cerebral ischaemia occurs, we investigated the influence of timing of thiopentone sodium administration on the neurotoxicity induced by nitric oxide (NO) using Shibuta's established model of primary brain cultures. Cortical neurones prepared from 16-day gestational rat foetuses were used after 13-14 days in culture. The cells were exposed to an NO-donor, NOC-5 at 30 microM. Thiopentone sodium administered at 30 and 10 min before or 5, 10 and 15 min after exposure to NOC-5, but not thereafter, significantly attenuated NO-induced neurotoxicity compared with controls. The survival rate of the neurones in which thiopentone sodium was administered at 15 min after exposure to NOC-5 was 55.7+/-2.4%, compared to a 10.0+/-1.6% survival rate in neurones when thiopentone sodium was administered at 30 min after exposure to NOC-5. These findings demonstrate that thiopentone sodium, which protects cerebral cortical neurones against NO-mediated cytotoxicity, should be given as soon as possible in case ischaemic or hypoxic neuronal damage is predicted.

Nitric oxide-induced cytotoxicity attenuation by thiopentone sodium but not pentobarbitone sodium in primary brain cultures

1. We describe the effects of barbiturates on the neurotoxicity induced by nitric oxide (NO) on foetal rat cultured cortical and hippocampal neurones. Cessation of cerebral blood flow leads to an initiation of a neurotoxic cascade including NO and peroxynitrite. Barbiturates are often used to protect neurones against cerebrovascular disorders clinically. However, its neuroprotective mechanism remains unclear. 2. In the present experiment, we established a new in vitro model of brain injury mediated by NO with an NO-donor, 1-hydroxy-2-oxo-3-(3-aminopropyl)-3-isopropyl-1-triazene (NOC-5) on grid tissue culture wells. We also investigated the mechanisms of protection of CNS neurones from NO-induced neurotoxicity by thiopentone sodium, which contains a sulphydryl group (SH-) in the medium, and pentobarbitone sodium, which does not contain SH-. 3. Primary cultures of cortical and hippocampal neurones (prepared from 16-day gestational rat foetuses) were used after 13-14 days in culture. The cells were exposed to NOC-5 at the various concentrations for 24 h in the culture to evaluate a dose-dependent effect of NOC-5. 4. To evaluate the role of the barbiturates, neurones were exposed to 4, 40 and 400 microM of thiopentone sodium or pentobarbitone sodium with or without 30 microM NOC-5. In addition, superoxide dismutase (SOD) at 1000 u ml(-1) and 30 microM NOC-5 were co-administered for 24 h to evaluate the role of SOD. 5. Exposure to NOC-5 induced neural cell death in a dose-dependent manner in both cortical and hippocampal cultured neurones. Approximately 90% of the cultured neurones were killed by 100 microM NOC-5. 6. This NOC-5-induced neurotoxicity was significantly attenuated by high concentrations of thiopentone sodium (40 and 400 microM) as well as SOD, but not by pentobarbitone sodium. The survival rates of the cortical neurones and hippocampal neurones that were exposed to 30 microM NOC-5 were 11.2+/-4.2% and 37.2+/-3.0%, respectively, and in the presence of 400 microM thiopentone sodium, the survival rate increased to 65.3+/-3.5% in the cortical neurones and 74.6+/-2.2% in the hippocampal neurones. 7. These findings demonstrate that thiopentone sodium, which acts as a free radical scavenger, protects the CNS neurones against NO-mediated cytotoxicity in vitro. In conclusion, thiopentone sodium is one of the best of the currently available pharmacological agents for protection of neurones against intraoperative cerebral ischaemia.

Rapid development of nitric oxide-induced hyperalgesia depends on an alternate to the cGMP-mediated pathway in the rat neuropathic pain model

Intrathecal injection of a nitric oxide releasing compound, NOC-18, was used to define the role of nitric oxide (NO) in the spinal mechanism of neuropathic pain caused by unilateral chronic constriction injury to rat sciatic nerves. Paw withdrawal latency was used to evaluate nociception induced by thermal stimuli before surgery and afterwards at 1, 3, and 6 h, and on days 1, 2, 3, 4, 5, 8, and 12 after the nerve ligature. In the sham-surgery control groups, intrathecal injection of 10 or 100 microg of NOC-18 did not produce any change in withdrawal latencies. In rats with unilateral nerve ligation, however, administration of 1 or 10 microg, but not 0.1 microg, of NOC-18 significantly shortened the time in which thermal hyperalgesia developed after nerve injury. Injection of 1 microg of NOC-18 decreased the onset time of thermal hyperalgesia from 2 days to 3 h and with 10 microg hyperalgesia developed within 1 h after the nerve injury. The effects of intrathecal injection of MK-801, a N-methyl-D-aspartate (NMDA) receptor antagonist, N-nitro-L-arginine methyl ester (L-NAME), a NO synthase inhibitor, methylene blue (MB), a soluble guanylate cyclase inhibitor, and hemoglobin (Hb), a NO scavenger, on the development of thermal hyperalgesia after the sciatic nerve ligature were examined in the presence and absence of 1 and 10 microg of NOC-18. Acceleration of the development of thermal hyperalgesia induced by 1 and 10 microg NOC-18 was completely inhibited by Hb, but was not affected by either MK-801, L-NAME or MB. These findings indicate that NO plays an important role in the rapid development of thermal hyperalgesia after the nerve injury, but that facilitation of nociceptive processing in the spinal cord may entail an alternate to the NO-cyclic guanosine 3',5'-monophosphate (cGMP) pathway.

Intrathecal administration of a new nitric oxide donor, NOC-18, produces acute thermal hyperalgesia in the rat

A nitric oxide releasing compound, NOC-18, was injected intrathecally in order to determine the role of NO in spinal nociceptive mechanisms in rats. The nociceptive threshold was evaluated by the radiant heat tail-flick test. The effects of intrathecal injection of N-nitro-L-arginine methyl ester (L-NAME), an NO synthase inhibitor; methylene blue (MB), a soluble guanylate cyclase inhibitor and hemoglobin (Hb), an NO scavenger, on the nociceptive threshold were measured in the presence and absence of 0.1, 1 and 10 microg of NOC-18. The results were compared with a control group of rats which were injected with the same volume of normal saline. NOC-18 caused a dose-dependent curtailment of the tail-flick latency during the period from 15 to 150 min. L-NAME, MB and Hb all produced prolongation of the tail-flick latency during the same time period. The hyperalgesia induced by this concentration range of NOC-18 was completely blocked by Hb, but was not affected by either L-NAME or MB. These findings indicate that NO plays a direct role in thermal hyperalgesia in the spinal cord, and that an another pathway in addition to the NO-cGMP pathway may be involved.

A comparative study of the antinociceptive action of xenon and nitrous oxide in rats

We attempted to clarify the mechanism of antinociceptive action induced by xenon and nitrous oxide. Eighty percent of nitrous oxide or 80% xenon was applied to rats inside enclosed clear plastic glass cylinders with their tails protruding for assessment of the tail-flick response to radiant heat. With repeated testing, there was a rapid reduction to nitrous oxide antinociception within 90 min, which was interpreted as development of tolerance, but not to xenon antinociception. Nitrous oxide antinociception was blocked by the intraperitoneal administration of 0.1 or 1.0 mg/kg yohimbine, but not by 1.0 or 5.0 mg/kg L659-066 or by 5.0 or 10 mg/kg naloxone. Xenon antinociception was not affected by any of these drugs. Yohimbine and L659-066 are characterized as alpha 2-adrenoceptor antagonists. Although yohimbine penetrates the blood-brain barrier after systemic administration, L659-066 does not penetrate it and act peripherally. Therefore, the results indicate that alpha 2-adrenoceptors, but not opioid receptors, may play a key role in antinociception induced by nitrous oxide in the central nervous system. Furthermore, the mechanism of xenon antinociception differs from that of nitrous oxide because it does not involve either alpha 2 or opioid receptors.

IMPLICATIONS

The precise mechanism of antinociceptive action of nitrous oxide and xenon remains unknown. It is still controversial whether an opioid system plays a role in antinociception induced by nitrous oxide. The results of the study showed that antagonism of central alpha 2-adrenoceptors, but not opioid receptors, reverses the antinociception induced by nitrous oxide but not by xenon, which indicates that alpha 2-adrenoceptors may play a key role in nitrous oxide antinociception.

Cardiovascular effects of an ultra-short-acting nitric oxide-releasing compound, zwitterionic diamine/NO adduct, in dogs

BACKGROUND

This study was conducted to clarify the cardiovascular effects of a new NO-releasing compound, NOC-7, and to compare it with other nitrovasodilators, sodium nitroprusside (SNP) and nitroglycerin, in dogs anesthetized with pentobarbital.

METHODS AND RESULTS

A bolus injection of NOC-7 decreased mean aortic blood pressure in a dose-dependent manner. The onset was rapid and the recovery quick. Continuous infusion of NOC-7 decreased mean aortic pressure from 115 +/- 3.9 to 84 +/- 2.9 mm Hg and infusion of SNP, from 118 +/- 3.8 to 87 +/- 3.1 mm Hg. The optimum doses of NOC-7 and SNP were determined to be 2.73 +/- 0.77 and 11.5 +/- 6.1 micrograms.kg-1.min-1, respectively. During infusion of NOC-7, heart rate and cardiac output were increased (P < .05), pulmonary artery pressure was not changed, and systemic and pulmonary vascular resistances were decreased (P < .05). Electromagnetic flowmetry showed that portal venous and internal carotid arterial blood flow were increased (P < .05) and that hepatic and renal arterial blood flows were not changed. These hemodynamic changes during NOC-7 infusion were similar to those with SNP. The plasma level of NO2-/NO3 did not change, but methemoglobin increased slightly (P < .05). Comparison between hypotensive responses before and after a 3.5-hour infusion of NOC-7 or nitroglycerin showed that acute tolerance developed to nitroglycerin but not to NOC-7.

CONCLUSIONS

The results indicate that NOC-7 may be useful as an ultra-short-acting nitrovasodilator that has no major adverse effect or tolerance.

A new nitric oxide donor, NOC-18, exhibits a nociceptive effect in the rat formalin model

The utility of a new nitric oxide (NO) donor, NOC-18, and the contribution of the neurotransmitter NO to nociception in response to tissue injury in rats, were examined following the subcutaneous injection of formalin into the hindpaw. This model induces biphasic responses in pain-related behavior, such that C-fiber activation during the first phase triggers a state of central sensitization characterized by the second phase. Formalin-induced nociceptive behavior was facilitated by intracerebroventricular administration of NOC-18 in the second phase, but not the first phase. This enhancement was completely abolished by the soluble guanylate cyclase inhibitor, methylene blue. These findings indicate that NO causes nociception via the NO-cGMP pathway in the central nervous system and NOC-18 proved to be a convenient and useful tool for the investigation of nociception-related NO.

Intracerebroventricular administration of a nitric oxide-releasing compound, NOC-18, produces thermal hyperalgesia in rats

This study was undertaken to define the role of nitric oxide (NO) in central nociceptive mechanisms by intracerebroventricular injection of an NO-releasing compound, NOC-18, in rats. The nociceptive threshold was evaluated by the radiant heat tail-flick test. Sixty-nine rats were divided into the seven groups, and the following drugs were injected intracerebroventricularly in 5 microliters of saline: no drug (control) (n = 13), 15 micrograms of NOC-18 (n = 15); 150 micrograms of NOC-18 (n = 9); 100 micrograms of N-nitro-L-arginine methyl ester (L-NAME) (n = 8); 15 micrograms of NOC-18 + 100 micrograms of L-NAME (n = 8); 10 micrograms of methylene blue (MB) (n = 8); 15 micrograms of NOC-18 + 10 micrograms of MB (n = 8). NOC-18 caused a dose-dependent curtailment (7% and 23% decreases for 15 micrograms and 150 micrograms of NOC-18, respectively) of the tail-flick latency during the period from 15 to 120 min. L-NAME caused prolongation (15% maximum) of the tail-flick latency during the period from 15 to 150 min. However, NOC-18-induced hyperalgesia was not influenced by L-NAME. MB also caused prolongation (9% maximum) of the tail-flick latency during the period from 15 to 150 min, and completely blocked the hyperalgesia induced by 15 micrograms of NOC-18. These findings indicate that the NO-cGMP pathway is directly involved in thermal hyperalgesia in the brain.