Sachiko Iwata

Therapeutic time window duration decreases with increasing severity of cerebral hypoxia-ischaemia under normothermia and delayed hypothermia in newborn piglets

OBJECTIVEnFor optimal neuroprotection following transient perinatal hypoxia-ischaemia (HI), therapy should start before overt secondary energy failure and its irreversible neurotoxic cascade. Hypothermia is a promising neuroprotective intervention that also prolongs the therapeutic time window (latent-phase; the period between re-establishment of apparently normal cerebral metabolism after HI, and the start of secondary energy failure). The influences of HI severity on latent-phase duration and regional neuroprotection are unclear. Under normothermia and delayed whole-body cooling to 35 and 33 degrees C we aimed to assess relationships between HI severity and: (i) latent-phase duration; (ii) secondary-energy-failure severity; and (iii) neuronal injury 48 h following HI.nnnMETHODSnNewborn piglets were randomized to: (i) HI-normothermia (n=12), (ii) HI-35 degrees C (n=7), and (iii) HI-33 degrees C (n=10). HI-35 degrees C and HI-33 degrees C piglets were cooled between 2 and 26 h after HI. Insult and secondary-energy-failure severity and latent-phase duration were evaluated using phosphorus magnetic resonance spectroscopy and compared with neuronal death in cortical-grey and deep-grey matter.nnnRESULTSnMore severe HI was associated with shorter latent-phase (p=0.002), worse secondary energy failure (p=0.023) and more cortical-grey-matter neuronal death (p=0.016).nnnCONCLUSIONSnLatent-phase duration is inversely related to insult severity; latent-phase brevity may explain the apparently less effective neuroprotection following severe cerebral HI.

Utility of Subjective Sleep Assessment Tools for Healthy Preschool Children: A Comparative Study Between Sleep Logs, Questionnaires, and Actigraphy

Background Sleep pattern is an important factor in a child’s mental, behavioural and physical status. To evaluate the sleep patterns of children, subjective tools such as sleep logs and questionnaires are still widely used in addition to objective methods of sleep assessment. Despite the established correlation between subjective and objective sleep variables, the characteristic features of subjective assessment have not been elucidated. Methods To investigate the characteristics of parental sleep assessment (daily sleep log and brief questionnaire) in preschool children, a 7-day actigraphic sleep study was conducted in 48 healthy 5-year-old children. Results Sleep schedule variables in the parental reports generally correlated well with actigraphic assessment of sleep patterns; however, sleep periods were longer in parental reports than in actigraphic recordings. Although the daily sleep log was better correlated with actigraphy, the brief questionnaire showed a good correlation with sleep pattern on weekday actigraphic assessments. Parental reports recorded fewer than 10% of the night wakings recorded by actigraphy. Conclusions Subjective sleep assessments remain useful, although their utility depends on the purpose and size of the study in question. However, knowledge of the potential biases and characteristics of such assessments is essential for correct interpretation of the data.

Qualitative Brain MRI at Term and Cognitive Outcomes at 9 Years After Very Preterm Birth

OBJECTIVE: A prospective study was performed to assess the relationship between the appearance of cerebral MRI at term and the cognitive functioning at 9 years old in very preterm born infants. METHODS: Seventy-six very preterm born infants (birth weight <1500 g or gestational age ≤32 weeks) obtained cerebral MRI at term-equivalent period, which was assessed by using established composite scores for the white and gray matter; cognitive outcomes at 9 years old were assessed in 60 subjects by using Wechsler Intelligence Scale for Children, Third Edition. RESULTS: Mildly low scores on the different IQ indices (<85) were observed in 23.3% (verbal IQ), 41.7% (performance IQ), and 30.0% (full-scale IQ) of the cohort, whereas moderately low scores (<70) were noted in 3.3% (verbal IQ), 11.7% (performance IQ), and 11.7% (full-scale IQ); cerebral palsy was diagnosed in 10.0%, whereas special assistance at school was required in 56.7%. Abnormal white matter appearances predicted mildly low verbal, performance, and full-scale IQs; moderately low performance and full-scale IQs; cerebral palsy; and the requirement for special assistance at school. Abnormal white matter appearances predicted mild cognitive impairment even after the adjustment for known clinical risk factors. In contrast, abnormal gray matter appearances did not predict any of the outcome measures. CONCLUSIONS: In a cohort of very preterm born infants, abnormal white matter appearance on term MRI showed consistent associations with cognitive impairments at 9 years old, further supporting the benefit of obtaining term MRI for very preterm born infants.

Depth of delayed cooling alters neuroprotection pattern after hypoxia-ischemia

Hypothermia after perinatal hypoxia‐ischemia (HI) is neuroprotective; the precise brain temperature that provides optimal protection is unknown. To assess the pattern of brain injury with 3 different rectal temperatures, we randomized 42 newborn piglets: (Group i) sham‐normothermia (38.5–39°C); (Group ii) sham‐33°C; (Group iii) HI‐normothermia; (Group iv) HI‐35°C; and (Group v) HI‐33°C. Groups iii through v were subjected to transient HI insult. Groups ii, iv, and v were cooled to their target rectal temperatures between 2 and 26 hours after resuscitation. Experiments were terminated at 48 hours. Compared with normothermia, hypothermia at 35°C led to 25 and 39% increases in neuronal viability in cortical gray matter (GM) and deep GM, respectively (both p < 0.05); hypothermia at 33°C resulted in a 55% increase in neuronal viability in cortical GM (p < 0.01) but no significant increase in neuronal viability in deep GM. Comparing hypothermia at 35 and 33°C, 35°C resulted in more viable neurons in deep GM, whereas 33°C resulted in more viable neurons in cortical GM (both p < 0.05). These results suggest that optimal neuroprotection by delayed hypothermia may occur at different temperatures in the cortical and deep GM. To obtain maximum benefit, you may need to design patient‐specific hypothermia protocols by combining systemic and selective cooling. Ann Neurol 2005;58:75–87

Delayed whole-body cooling to 33 or 35 degrees C and the development of impaired energy generation consequential to transient cerebral hypoxia-ischemia in the newborn piglet.

OBJECTIVES. Fundamental questions remain about the precise temperature providing optimal neuroprotection after perinatal hypoxia-ischemia (HI). Furthermore, if hypothermia delays the onset of the neurotoxic cascade and the secondary impairment in cerebral energy generation, the “latent phase” may be prolonged, thus extending the period when additional treatments may be effective. The aims of this study were to investigate the effects of delayed systemic cooling at either 33°C or 35°C on the following: (1) latent-phase duration, and (2) cerebral metabolism during secondary energy failure itself, in the 48-hour period after transient HI. METHODS. Piglets were randomly assigned to the following: (1) HI-normothermic (HI-n) rectal temperature (Trectal; n = 12), (2) HI-Trectal 35°C (HI-35; n = 7), and (3) HI-Trectal 33°C (HI-33; n = 10). Groups were cooled to the target Trectal between 2 and 26 hours after HI. Serial magnetic resonance spectroscopy was performed over 48 hours. The effect of cooling on secondary energy failure severity (indexed by the nucleotide triphosphate/exchangeable phosphate pool [NTP/EPP] and phosphocreatine/inorganic phosphate [PCr/Pi] ratios) was assessed. RESULTS. Compared with HI-n, HI-35 and HI-33 had a longer NTP/EPP latent phase and during the entire study duration had higher mean NTP/EPP and PCr/Pi. The latent phase (both PCr/Pi and NTP/EPP) and the whole-brain cerebral energetics were similar for HI-35 and HI-33. During the hypothermic period, compared with HI-n, PCr/Pi was preserved in the cooled groups, but this advantage was not maintained after rewarming. Compared with HI-n, HI-35 and HI-33 had higher NTP/EPP after rewarming. CONCLUSIONS. Whole-body hypothermia for 24 hours at either 35 or 33°C, commenced 2 hours after resuscitation, prolonged the NTP/EPP latent phase and reduced the overall secondary falls in mean PCr/Pi and NTP/EPP during 48 hours after HI. Reducing the temperature from 35 to 33°C neither increased mean PCr/Pi and NTP/EPP nor further lengthened the latent phase.

Determinants of outcomes following acute child encephalopathy and encephalitis: pivotal effect of early and delayed cooling

Background Acute encephalopathy/encephalitis is one of the most important causatives of mortality and neurological deficit during childhood. The aim of this retrospective observational study was to investigate clinical variables and therapeutic options associated with the outcome of children with acute encephalopathy/encephalitis. Methods Relationships between the clinical information at admission and the neurological outcome evaluated using Pediatric Cerebral Performance Category Scale (PCPC) at 12 months after admission were assessed in 43 patients who were treated at 10 Japanese paediatric intensive care units. Results Sixteen patients were cared for at normothermia, whereas mild hypothermia was applied to 27 children. In univariate analysis, ages ≤18 months, marked elevation in serum lactate dehydrogenase (LD) and aspartate transaminase, diagnosis of either acute necrotising encephalopathy or haemorrhagic shock and encephalopathy syndrome and longer hypothermic periods were associated with increased risks of death or severe neurological deficit, whereas hypothermia showed pivotal effects: the outcome of children cooled after 12 h of diagnosis was statistically invariant with normothermic children, but was significantly worse compared with children cooled ≤12 h. In multivariate analysis, younger ages and elevated serum LD were associated with adverse outcomes, whereas early initiation of cooling was related to favourable outcomes. For normothermic children, PCPC scores were dependent on the computed tomographic findings suggestive of cerebral oedema, serum LD levels and Glasgow Coma Scale at admission. For hypothermic children, PCPC scores depended on longer delays in cooling initiation. Conclusion Without therapeutic hypothermia, the outcome of children was determined by variables suggestive of the severity of encephalopathy/encephalitis at admission. Hypothermia may have pivotal impacts on the outcome of children according to the timing of cooling initiation following acute encephalopathy/encephalitis.

Determinants of sleep patterns in healthy Japanese 5-year-old children.

Early childhood is an important period for the development of sleep patterns; studies of sleep patterns in young preschool children may help elucidate the mechanism of associated mental/physical conditions and later sleep problems.

Diurnal Cortisol Changes in Newborn Infants Suggesting Entrainment of Peripheral Circadian Clock in Utero and at Birth

BACKGROUNDnIn the rodent and human fetus, a diurnal cortisol rhythm is observed that is entrained in antiphase to the maternal rhythm. However, after birth, the adrenal circadian rhythm becomes unsynchronized with the clock time, and an adult-type, 24-h rhythm is observed only after a few months. Little is known about when and how the fetal adrenal circadian rhythm is synchronized with the day-night cycle.nnnMETHODSnTo investigate the function of adrenal circadian clock in the newborn infant, eight serial saliva samples were collected every 3 h over 24 h (starting at 0900 h) in 27 newborn infants.nnnRESULTSnCortisol levels were higher during the period 1500 to earlier than 2100 h than during 0900 to earlier than 1500 h and 0300 to earlier than 0900 h (both P < 0.05). Salivary cortisol levels collected during 0 to <6, 6 to <12, and 12 to <18 hours after the clock time at birth (birth time) were higher than those collected during 18 to <24 hours after the birth time (P < 0.005, 0.05, and 0.05, respectively). The acrophase of salivary cortisol was linearly correlated with the birth time within the first 5 d of life (P < 0.005) but not thereafter.nnnCONCLUSIONnIn the newborn infant, diurnal increase in cortisol was observed in the late afternoon and in correspondence with the birth time. The adrenal circadian rhythm acquired in utero may be reentrained by endocrinological events at birth. Such complex regulation of the adrenal circadian clock may inhibit a swift synchronization of the circadian clock to the day-night rhythm.

Methyl‐isobutyl amiloride reduces brain Lac/NAA, cell death and microglial activation in a perinatal asphyxia model

Na+/H+ exchanger (NHE) blockade attenuates the detrimental consequences of ischaemia and reperfusion in myocardium and brain in adult and neonatal animal studies. Our aim was to use magnetic resonance spectroscopy (MRS) biomarkers and immunohistochemistry to investigate the cerebral effects of the NHE inhibitor, methyl isobutyl amiloride (MIA) given after severe perinatal asphyxia in the piglet. Eighteen male piglets (aged < 24 h) underwent transient global cerebral hypoxia‐ischaemia and were randomized to (i) saline placebo; or (ii) 3 mg/kg intravenous MIA administered 10 min post‐insult and 8 hourly thereafter. Serial phosphorus‐31 (31P) and proton (1H) MRS data were acquired before, during and up to 48 h after hypoxia‐ischaemia and metabolite‐ratio time‐series Area under the Curve (AUC) calculated. At 48 h, histological and immunohistochemical assessments quantified regional tissue injury. MIA decreased thalamic lactate/N‐acetylaspartate and lactate/creatine AUCs (both p < 0.05) compared with placebo. Correlating with improved cerebral energy metabolism, transferase mediated biotinylated d‐UTP nick end‐labelling (TUNEL) positive cell density was reduced in the MIA group in cerebral cortex, thalamus and white matter (all p < 0.05) and caspase 3 immunoreactive cells were reduced in pyriform cortex and caudate nucleus (both p < 0.05). Microglial activation was reduced in pyriform and midtemporal cortex (both p < 0.05). Treatment with MIA starting 10 min after hypoxia‐ischaemia was neuroprotective in this perinatal asphyxia model.

Age and gender specific prevalence of HTLV-1

BACKGROUNDnThe seroprevalence of Human T-cell Leukemia Virus Type 1 (HTLV-1) is female predominant despite the higher incidence of Adult T-cell Leukemia (ATL) in males. If the mother-to-child transmission of HTLV-1 is more common for male infants than in female infants, longer exposure to the virus for males may explain the paradoxically higher incidence of ATL.nnnOBJECTIVESnTo test the hypothesis that the seroprevalence of HTLV-1 is male predominant during adolescence.nnnSTUDY DESIGNnThe presence of HTLV-1 antibody in 272,043 blood samples donated to a regional blood bank in an HTLV-1 high-endemic region was assessed.nnnRESULTSnThe entire population of female donors had a significantly higher seroprevalence compared to males (2.05% and 1.80%, respectively, p<0.0001). However, compared with male donors, the carrier rate for female donors was lower for the youngest subgroup (16-19 years, p=0.0011); was similar for the next two age subgroups (20-29 years and 30-39 years); and was significantly higher for the last two age subgroups (40-49 years and over 50-64 years, both p<0.0001). In general, older age subgroups led to higher seroprevalence in both genders.nnnCONCLUSIONSnHTLV-1 infection is more common for males until after age 20, when male to female sexual transmission becomes likely. This suggests that mother-to-child transmission is more common for males.