Publications by authors named "Kensuke Okubo"

Introduction: EGMAIN-GX is the computerized physician order entry system used in Japan. The automatic rounding-off of the calculated dose of chemotherapeutic drugs is an update in version 4, compared to version 2. We conducted a comparative study between EGMAIN-GX versions 2 and 4 to estimate the effect of the automatic rounding-off function on ordering time and dose dispersion.

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Background: The measurement of transcutaneous bilirubin (TcB) is very important to screen for hyperbilirubinemia in newborns. Until now, however, there has been no hour-specific, percentile-based TcB nomogram during the early neonatal period in Japanese neonates. The aim of this study was to develop a TcB nomogram within 72 h of birth in Japanese neonates.

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The purpose of this study was to examine developmental changes in visuocognitive function, particularly face recognition, in early infancy. In this study, we measured eye movement in healthy infants with a preference gaze problem, particularly eye movement between two face stimulations. We used the eye tracker system (Tobii1750, Tobii Technologies, Sweden) to measure eye movement in infants.

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Background: To evaluate the clinical effects of phototherapy for neonatal hyperbilirubinemia, it is necessary to measure the rate of cyclobilirubin production, which represents the main photochemical pathway of bilirubin metabolism. Since the Atom Phototherapy Analyzer can be used to calculate the theoretical relative light energy of irradiance as a means of assessing the cyclobilirubin production rate for each wavelength spectrum, the clinical effect of phototherapy can be evaluated regardless of the light source type. Using the Atom Phototherapy Analyzer, the correlation between the irradiance of various light sources with different peak wavelengths and the rate of cyclobilirubin production was investigated in vitro.

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Multichannel near-infrared spectroscopy (MNIRS) was used for the functional imaging of the sensorimotor cortex of newborn infants during passive knee and elbow movement under sedated sleep. Contralateral knee and elbow movement caused a marked increase in the concentration of oxyhemoglobin ([oxyHb]) from the baseline values at site within the sensorimotor area in all infants. During ipsilateral knee and elbow movement, [oxyHb] showed smaller changes, equivalent to 64 ± 23 and 66 ± 28% of the changes that occurred with contralateral stimulation, respectively.

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The aim of this study was to evaluate the hypothesis that cerebral hemoglobin (Hb) oxygenation is related to phosphorylation potential during primary and secondary cerebral energy failure in newborn infants who have experienced birth asphyxia. We subjected newborn piglets to severe transient cerebral hypoxic-ischemia followed by resuscitation and examined cerebral energy metabolism by 31P-magnetic resonance spectroscopy and evaluated changes in cerebral Hb oxygen saturation (ScO2) using full-spectrum near-infrared spectroscopy before, during, and up to 54 h after the hypoxic-ischemic insult. ScO2 was significantly decreased during the hypoxic-ischemic insult compared with baseline values.

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Article Synopsis
  • The study used optical topography to compare cerebral oxygenation changes in preterm and term infants when exposed to verbal stimuli, specifically a recording of a Japanese fairy tale.
  • Eight preterm infants (gestational age 23-34 weeks) and ten term infants (2-11 days old) were observed at the same postconceptional age (38-46 weeks).
  • Preterm infants showed a significantly shorter response time to verbal stimulation, indicating that their brain development—especially in auditory processing and neuro-vascular coupling—is influenced more by the days after birth than by their postconceptional age.
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Background: The light-emitting diode is used as one of the new light sources for phototherapy. NeoBLUE (Atom Medical, Tokyo, Japan) incorporates blue light-emitting diodes for the treatment of neonatal hyperbilirubinemia. The authors compared the in vitro efficacy of neoBLUE with conventional phototherapy devices.

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Near-infrared spectroscopy has been used for measurement of changes in cerebral Hb concentrations in infants to study cerebral oxygenation and hemodynamics. In this study, measurements by time-resolved spectroscopy (TRS) were performed in 22 neonates to estimate the values of light absorption coefficient and reduced scattering coefficient (mu'(s)), cerebral Hb oxygen saturation (SCO2), cerebral blood volume (CBV), and differential pathlength factor (DPF), and the relationships between postconceptional age and mu'(s), SCO2, CBV, and DPF were investigated. A portable three-wavelength TRS system with a probe attached to the head of the neonate was used.

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Background: Phototherapy has been a standard treatment for neonatal hyperbilirubinemia for more than 40 years, but it has remained sub-optimal.

Aims: To clarify the developmental changes in parameters of (4E, 15Z)-cyclobilirubin ((EZ)-C) elimination in order to obtain basic data for establishing optimal phototherapy.

Study Design: Blood samples were taken at regular intervals after stopping phototherapy, and bilirubin fractions were analyzed by high-performance liquid chromatography.

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Near-infrared spectroscopy (NIRS) has been used for measurement of cerebral hemoglobin (Hb) concentrations in neonates to study cerebral oxygenation and hemodynamics. We perform measurements by portable three-wavelength NIR time-resolved spectroscopy (TRS) in a piglet hypoxia model with various degrees of oxygenation to estimate the absorption coefficient (mu(a)) and reduced scattering coefficient (mu(s)') of the head. Measurements of absolute values of mu(a) at three wavelengths enable estimation of Hb concentration and Hb oxygen saturation in the head (SO2).

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Background: The developmental changes of the umbilical cortisol levels in neonates at gestational age of 23-41 weeks were studied and the effect of antenatal steroid administration on the umbilical cortisol levels were examined.

Methods: Cortisol levels in the umbilical vein (UV) and the umbilical artery (UA) were studied in 35 neonates at the gestational age (GA) of 23-41 weeks with or without antenatal administration of corticosteroids. Serum cortisol concentrations were measured by the high performance liquid chromatography method.

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Background: Estimation of hemodynamics is important for critically ill infants. Pulse dye densitometry (PDD) using indocyanine green (ICG), which enables measurements of circulating blood volume at the bedside, has recently been developed for adults.

Methods: We conducted a basic investigation to determine whether this method can be applied to infants and measured circulating blood volume in 25 infants whose gestational ages ranged from 24 to 40 weeks (median, 32 weeks).

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Background: The clinical effect of phototherapy for neonatal hyperbilirubinemia is based on the production and elimination of cyclobilirubin. Generally, the clinical effect of light sources is estimated by the reduction in the total serum bilirubin level. One procedure with less invasiveness than blood collecting is urine collection.

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During the developmental stage, the brain undergoes anatomic, functional, and metabolic changes necessary to support the complex adaptive behavior of a mature individual. Estimation of developmental changes occurring in different regions of the brain would provide a means of relating various behavioral phenomena to maturation-specific brain structures, thereby providing useful information on structure-function relationships in both normal and disease states. We used multichannel near-infrared spectroscopy (MNIRS), a new noninvasive imaging technique for revealing the course of neural activity in selected brain regions, to monitor the activities of the visual cortex as mirrored by hemodynamic responses in infants subjected to photostimulation during natural sleep.

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The aim of this study was to determine the validity of the hypothesis that excitatory amino acids are related to phosphorylation potential during primary and secondary cerebral energy failure observed in asphyxiated infants. We report here the results of experiments using newborn piglets subjected to severe transient cerebral hypoxia-ischemia followed by resuscitation. We examined cerebral energy metabolism by phosphorus nuclear magnetic resonance spectroscopy and changes in levels of amino acid neurotransmitters in the cortex by microdialysis before, during, and up to 24 h after the hypoxic-ischemic insult.

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To investigate whether or not the mode of delivery produces differences in cerebral oxygenation, cerebral hemoglobin oxygen saturation was measured using full-spectrum near infrared spectroscopy in 26 healthy term newborn infants immediately after birth. Infants in group 1 (n=20) were delivered vaginally, and those in group 2 (n=6) by elective cesarean section. Arterial oxygen saturation in the right hand was also measured simultaneously using a pulse oximeter.

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The aim of this study was to quantify the relative concentrations of oxyhemoglobin and deoxyhemoglobin within the light path of the brain and to estimate cerebral hemoglobin (Hb) oxygen saturation using full-spectrum near-infrared spectroscopy (fsNIRS). For this purpose, we developed a novel exponential correction equation as well as a two-point spectroscopy method to estimate the relative concentrations of Hb and Hb oxygen saturation in biological tissues. The results of evaluation of measurements using an in vitro model indicated that our fsNIRS method enables accurate and non-invasive measurements of Hb content and saturation in a highly scattered medium such as the human brain.

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