Osuke Iwata

The AP-1 transcription factor c-Jun is required for efficient axonal regeneration

Nerve injury triggers numerous changes in the injured neurons and surrounding nonneuronal cells that ultimately result in successful target reinnervation or cell death. c-Jun is a component of the heterodimeric AP-1 transcription factor, and c-Jun is highly expressed in response to neuronal trauma. Here we have investigated the role of c-jun during axonal regeneration using mice lacking c-jun in the central nervous system. After transection of the facial nerve, the absence of c-Jun caused severe defects in several aspects of the axonal response, including perineuronal sprouting, lymphocyte recruitment, and microglial activation. c-Jun-deficient motorneurons were atrophic, resistant to axotomy-induced cell death, and showed reduced target muscle reinnervation. Expression of CD44, galanin, and alpha7beta1 integrin, molecules known to be involved in regeneration, was greatly impaired, suggesting a mechanism for c-Jun-mediated axonal growth. Taken together, our results identify c-Jun as an important regulator of axonal regeneration in the injured central nervous system.

Therapeutic hypothermia for birth asphyxia in low-resource settings: a pilot randomised controlled trial

This letter describes a study done at Mulago Hospital Kampala Uganda aimed at determining the feasibility of whole-body cooling by use of simple methods in a low-resource setting. The study performed after written informed parental consent randomly assigned standard care plus therapeutic hypothermia or standard care alone on infants within 3 hours of birth. Data suggests that therapeutic hypothermia with whole-body cooling screening informed consent and randomisation are feasible and inexpensive in a special-care baby unit in a low-resource setting. Rigorous randomised trials to determine the safety and efficacy of therapeutic hypothermia in this context are urgently needed so that any benefi ts of this novel therapy can reach areas of the world that might need it most. (excerpt)

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.

N-methyl-isobutyl-amiloride ameliorates brain injury when commenced before hypoxia ischemia in neonatal mice

Underphysiologic conditions, brain intracellular pH (pHi) is maintained at 7.03. Rebound brain intracellular alkalosis has been observed in experimental models and adult stroke after hypoxia/ischemia (HI). In term infants with neonatal encephalopathy (NE), an association exists between the magnitude of brain alkalosis and neurodevelopmental outcome, and there is increasing evidence to suggest that alkalosis may be deleterious to cell survival. Activation of the Na+/H+ exchanger (NHE) is thought to be responsible for the rapid normalization of pHi and rebound alkalosis after reperfusion. We hypothesized that N-methyl-isobutyl-amiloride (MIA), an inhibitor of the NHE, would reduce brain injury in a model of neonatal HI. Seven-day-old mice underwent left carotid artery occlusion followed by exposure to 8% oxygen for 30 min (moderate insult) or 1 h (severe insult). Animals received MIA or saline 8 hourly starting 30 min before HI. Outcome was determined at 48 h by measuring viable tissue in the injured hemisphere (severe insult) or injury score and TUNEL staining (moderate insult). After the severe insult, MIA had a significant neuroprotective effect increasing forebrain tissue survival from 44% to 67%. After the moderate insult, damage was localized to the hippocampus where treatment resulted in a significant reduction in injury score and in TUNEL-positive cells. MIA was also shown to have a significant overall neuroprotective effect based on injury score after the moderate insult. Amiloride analogues are neuroprotective when commenced before HI in a mouse model.

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.

Comparative Prognostic Utilities of Early Quantitative Magnetic Resonance Imaging Spin-Spin Relaxometry and Proton Magnetic Resonance Spectroscopy in Neonatal Encephalopathy

OBJECTIVE. We sought to compare the prognostic utilities of early MRI spin-spin relaxometry and proton magnetic resonance spectroscopy in neonatal encephalopathy. METHODS. Twenty-one term infants with neonatal encephalopathy were studied at a mean age of 3.1 days (range: 1–5). Basal ganglia, thalamic and frontal, parietal, and occipital white matter spin-spin relaxation times were determined from images with echo times of 25 and 200 milliseconds. Metabolite ratios were determined from an 8-mL thalamic-region magnetic resonance spectroscopy voxel (1H point-resolved spectroscopy; echo time 270 milliseconds). Outcomes were assigned at age 1 year as follows: (1) normal, (2) moderate (neuromotor signs or Griffiths developmental quotient of 75–84), (3) severe (functional neuromotor deficit or developmental quotient <75 or died). Predictive efficacies for differentiation between normal and adverse (combined moderate and severe) outcomes were compared by receiver operating characteristic curve analysis and logistic regression. RESULTS. Thalamic and basal ganglia spin-spin relaxation times correlated positively with outcome and predicted adversity. Although thalamic and basal ganglia spin-spin relaxation times were prognostic of adversity, magnetic resonance spectroscopy metabolite ratios were better predictors, and, of these, lactate/N-acetylaspartate was most accurate. CONCLUSIONS. Deep gray matter spin-spin relaxation time was increased in the first few days after birth in infants with an adverse outcome. Proton magnetic resonance spectroscopy was more prognostic than spin-spin relaxation time, with lactate/N-acetylaspartate the best measure. Nevertheless, both techniques were useful for early prognosis, and the potential superior spatial resolution of spin-spin relaxometry may define better the precise anatomic pattern of injury in the early days after birth.