Codon reading patterns in Drosophila melanogaster mitochondria based on their tRNA sequences: a unique wobble rule in animal mitochondria.

Mitochondrial (mt) tRNA(Trp), tRNA(Ile), tRNA(Met), tRNA(Ser)GCU, tRNA(Asn)and tRNA(Lys)were purified from Drosophila melanogaster (fruit fly) and their nucleotide sequences were determined. tRNA(Lys)corresponding to both AAA and AAG lysine codons was found to contain the anticodon CUU, C34 at the wobble position being unmodified. tRNA(Met)corresponding to both AUA and AUG methionine codons was found to contain 5-formylcytidine (f(5)C) at the wobble position, although the extent of modification is partial. These results suggest that both C and f(5)C as the wobble bases at the anticodon first position (position 34) can recognize A at the codon third position (position 3) in the fruit fly mt translation system. tRNA(Ser)GCU corresponding to AGU, AGC and AGA serine codons was found to contain unmodified G at the anticodon wobble position, suggesting the utilization of an unconventional G34-A3 base pair during translation. When these tRNA anticodon sequences are compared with those of other animal counterparts, it is concluded that either unmodified C or G at the wobble position can recognize A at the codon third position and that modification from A to t(6)A at position 37, 3'-adjacent to the anticodon, seems to be important for tRNA possessing C34 to recognize A3 in the mRNA in the fruit fly mt translation system.

Clinical markers in CSF for determining neurologic deficits after thoracoabdominal aortic aneurysm repairs.

BACKGROUND: Spinal cord ischemia is a major cause of morbidity and mortality after thoracoabdominal aortic aneurysm operations. The incidence of paraplegia is high even in experienced institutions. METHODS: We investigated whether neurotransmitter excitotoxicity is associated with neurologic deficits after thoracoabdominal aortic aneurysm operations. We hypothesized that patients with spinal cord injury would manifest elevated levels of excitatory amino acids in their cerebrospinal fluid. Sixteen patients undergoing thoracoabdominal aortic aneurysm operations had cerebrospinal fluid drawn through lumbar spinal drains preoperatively, intraoperatively, and postoperatively. Excitatory amino acid levels (glutamate, aspartate, glycine) were measured using high-performance liquid chromatography. Excitatory amino acid levels were compared in patients who exhibited no neurologic deficits postoperatively (group I; n = 12) with patients who had clinically evident lower extremity and cerebral neurologic deficits (group II; n = 4). RESULTS: Significant elevations in glutamate and aspartate levels from baseline (p < 0.05) were limited to group II. Excitatory amino acid levels in group II were significantly elevated (p < 0.05) compared with those observed in group I. Glutamate levels were especially increased during aortic cross-clamping and late reperfusion, whereas aspartate levels were increased only during late reperfusion. CONCLUSIONS: These data suggest that neurotransmitter excitotoxicity plays a significant role in central nervous system injury.

Brief post-hypoxic-ischemic hypothermia markedly delays neonatal brain injury.

The influence of post-insult temperature modulation on ischemic injury in immature brain was studied in 7-day-old rats that underwent a unilateral carotid artery ligation followed by exposure to hypoxia in 8% oxygen at an ambient temperature of 36.5 degrees C. After the hypoxic exposure, the animals were separated into three groups and placed for 3 h in temperature-controlled incubators set at 32 degrees C, 35 degrees C, and 38 degrees C. In Study 1, the influence of post-insult temperature modulation was assessed after graded cerebral hypoxic-ischemic injury. Brain damage was assessed 1 week after the insult by comparison of wet weights in the cerebral hemispheres ipsilateral and contralateral to the carotid artery ligation. Rectal temperatures of the animals significantly correlated with extent of brain injury after 60 min (Spearman correlation coefficient, p = 0.44, P = 0.005) and 90 min (p = 0.46, P = 0.004) but not 120 min of hypoxia (p = 0.18, P = 0.46). In Study 2, animals were exposed to 75 min hypoxia, and injury was assessed morphometrically and histologically at 1 and 4 weeks after the injury. Rectal temperatures significantly correlated with the extent of ischemic injury in the cerebral cortex (p = 0.3, P = 0.046) and striatum (p = 0.3, P = 0.048) at 1 week, but not 4 weeks, after the insult. The findings indicate that post-insult hypothermia delayed the expression of mild to moderate brain damage by more than a week, after which the damage was as severe as in normothermic animals. The results indicate that the events that determine the final expression of a neonatal hypoxic-ischemic insult can be extended over a long interval by post-insult hypothermia.

Ontogenic development of autoregressive component waves of waking EEG in normal infants and children.

Waking EEGs of 150 normal children aged from 20 days to 15 years were subjected to analysis. Discrete time series of an artifact free segment of the EEG record at 50 samples/sec for twenty seconds was generated and autoregressive (AR) and component analyses were carried out with a minicomputer PDP 11/40 (DEC). The results may be summarized as follows: 1) In the group of 1 year old and less, the power increased with the monthly age, whereas the bio-informing activity amount decreased. In those older than 1 year, both parameters showed maximal values at 1 year and then decreased with age, and the decreases were marked from 1 to 3 years. 2) The first- and second-order component activities of 129 and 677 waves, respectively, were obtained by applying component analysis to 152 EEG records. The frequency polygons of natural frequency of second-order component waves verified several modes, each of which was enhanced in the frequency range of the well-known delta 0, delta 1, theta 1, theta 2, alpha 1, alpha 2, beta 1, beta 2 and beta 3 waves, respectively. 3) The average percent-power of the delta wave (delta 0 + delta 1) decreased with age, especially from 1 to 3 years old, whereas those of beta- and alpha-waves increased with advancing age. That of the theta wave tended to increase from 2 to 4 years of age, and thereafter decreased gradually with increasing age. 4) With increasing age, the durations of damped oscillations were significantly lengthened in delta 1, alpha 1 and beta 3 waves, whereas that in the theta 1 wave was significantly shortened. 5) The bio-informing activity amounts of alpha waves increased from 1 to 3 years with increasing age, whereas those of delta and theta waves decreased. No significant developmental change in the parameters, however, was observed in the beta wave. The results indicate that AR-power spectral and component analyses of EEG are sensitive methods for obtaining valuable information regarding the electrical brain maturation in childhood.

Ontogenic development of EEG-asymmetry in early infantile autism.

Autoregressive (AR) analysis and component analysis were done on EEGs during sleep stage 2 in normal and autistic children, since AR-coefficients of EEG characterize the autocovariance and power spectral density of EEG. In addition, as the generalized distance of the average AR-coefficient vector of an EEG group at one side from that at the opposite side exhibits an F-distribution, the statistical inferences were determined, as to whether there is hemispheric specialization in EEG in 21 right-handed autistic children and whether there is a difference between the AR-spectral pattern of EEG in the autistic children and that of 28 normal children of the same age range. The results obtained are as follows: 1. Significant hemispheric lateralization in EEG at the significant level of 0.01 was observed in normal children, whereas no lateralization was confirmed in autistic children. 2. Random click stimulation had cumulative effects on the hemispheric lateralization in the normal children, but not in the autistic children. On the contrary, the effects of random flash light stimulation on hemispheric asymmetry were verified in the autistic children as well as in the normal children. 3. The EEG components of autistic children were significantly different from the normal ones in the frequency range of alpha-2 component waves at bilateral frontal (Fp1 and Fp2) regions and the activity of these component waves was higher in the autistic children than in the normal ones over 5 years old. 4. These findings suggest that autistic children are not only less responsive to external stimuli, but also neurophysiologically less active in the internal regulatory mechanism.

[Hemispheric lateralization of EEG in early infantile autism].

Autoregressive (AR) analysis and component analysis were applied to EEGs during sleep stage 2 of normal and autistic children, since AR-coefficients of EEG characterize the autocovariance and power spectral density of EEG. In addition, as the Mahalanobis' generalized distance of the average AR coefficient vector of an EEG group at one side from that at the opposite side follows a F-distribution, the statistical inferences were carried out, whether or not there is hemispheric specialization in EEG in 21 right handed autistic children and whether there is difference between AR-spectral pattern of EEG in the autistic children and that of 28 normal children of the same age range or not. The results obtained were as follows: 1) The significant hemispheric lateralization in EEG at the significant level of 0.01 was observed in normals, whereas none of the lateralization was confirmed in autistic children. 2) The random click stimulation caused a cumulative effect on the hemispheric lateralization in the normals, but not in the autistic children. On the contrary, the effects of random flash light stimulation on hemispheric asymmetry were verified in the autistic children as well as in the normals. 3) The EEG components of autistic children were significantly different from the normal ones in frequency range of alpha-2 component wave at bilateral frontal (F1 and F2) regions and the activity of these component waves were higher in the autistic children than in the normal ones over 5 years-old. 4) These findings suggest that autistic children are not only less responsive to external stimuli, but also neurophysiologically less active in the internal regulatory mechanism.

[Developmental characteristics of topographic EEG in the newborn using an autoregressive model].

Using an autoregressive topographic mapping system, developmental changes in the total power of EEG in quiet and active sleep were studied in 23 normal premature infants aged from 34 to 40 weeks of postconceptional age. Pattern discrimination of topographic EEG between both sleep stages was also made. Tracé alternant patterns in quiet sleep and low voltage irregular patterns in active sleep were analyzed. Topographic maps of one segment (10.24 sec) and 10 segments of EEG showed small peaks in the frontal region and large peaks in the occipital region during both sleep stages, with the total power in quiet sleep exceeding that in active sleep. Total power decreased with increasing postconceptional age. In the pattern discrimination of topographic EEG between both sleep stages, significant differences were noted mainly in the frontal and occipital regions. It was concluded that topographic mapping of EEG disclosed spatial differences in EEG development in the newborn.

[An application of autoregressive model to pattern discrimination of brain electrical activity mapping].

We developed a method of illustrating significant regional differences between two records of brain electrical activity mapping (BEAM), using pattern discrimination of autoregressive (AR) EEG analysis. In this study, the EEG data could be objectively reduced to a few AR coefficients, and this statistical method was successfully applied to discrimination of differences in BEAM among records from two or more subjects. A significant difference was illustrated at the right parietal region between two age groups, 6 years and 8 years, in normal children. It was concluded that this new approach of BEAM analysis through a statistical taxonomy was clinically useful for evaluation of the normal development of BEAM in children and for localization of functional brain abnormalities.

[Status epilepticus in two patients with Sotos syndrome].

Two patients with Sotos syndrome showed very intractable and prolonged status epilepticus, resulting in poor outcomes. Clinical seizures and EEG abnormalities in patients with Sotos syndrome are sometimes noted, but they are usually mild. These two patients showed hypoplasia of corpus callosum on MRI. We considered the mechanism of intractable seizures, and emphasized the importance of careful management for their seizures and EEG abnormalities.

[Developmental characteristics of the alpha waves of EEG in normal healthy children].

The records of waking state electroencephalography (EEG) of 1,340 normal children aged from 3 to 12 years were subjected to analysis using an autoregressive model. The results were summarized as follows. (1) 6,814 components of second-order activities were obtained through component analysis of the 1,218 EEG records. The frequency polygons of damping frequency of the second-order component waves verified several modes, each of which was enhanced in the eight frequency ranges. (2) The average percent-power of the alpha-1 waves decreased with increasing ages from 3 years, whereas that of the alpha-2 waves increased. That of the alpha-3 waves showed no change with ages. (3) The average damping times of alpha-2 waves increased with increasing ages. (4) Dominancy in frequency showed a course of two step increments at 3-6 and 10 years of age. The former was chiefly due to the increase in the alpha-1 wave and the latter in the alpha-2 wave. There were no significant increases of alpha-3 waves. (5) By means of EEG pattern discrimination, the differences in alpha components among different age groups were obtained as generalized (Maharanobis') distances. The alpha-1 activity showed a significant difference in amount between the age group of 3-6 years and the other age groups. The alpha-2 activity showed a significant difference in amount between the age group of 10 years and the other age groups. (6) The development of brain activity proceeds faster in the posterior areas and relatively slower in the central areas.

[Developmental characteristics of the beta waves of EEG in normal healthy children].

By the use of an autoregressive (AR) model, development of beta-waves in quantitative EEG parameters was studied in 1,340 normal children aged from 3 to 12 years. The results were summarized as follows. The beta band(13.5-25 Hz) was divided into three frequency ranges; beta-1(13.5-17.4 Hz), beta-2(17.5-21.4 Hz) and beta-3 (21.5-25 Hz) waves. The average power and percent-power of the beta-1 and beta-2 waves increased with advancing age, whereas these of the beta-3 wave showed no change with advancing age. By means of EEG pattern discrimination, critical period of beta band in the developing EEG was observed at the age of 4 years in frontal region, 10 years in central region and 3 to 7 years in occipital region. Those results suggest that the development of beta activity may be faster in frontal, occipital areas and relatively slower in central area.

Developmental characteristics of topographic EEG in the newborn using an autoregressive model.

Autoregressive topographic EEG analysis was used to determine topographic EEGs of the total power in quiet and active sleep stages in 33 healthy premature infants of 34 to 40 weeks conceptional age. The developmental characteristics were also examined by simultaneously referring to the autoregressive pattern discrimination of topographic EEGs between different conceptional age groups in both sleep stages. Treating 10.24 seconds of EEG as one segment, the topographic EEG of 10 segments in each of the quit and active sleep stages as well as their mean were obtained. In both sleep stages the results showed a small peak in total power in the frontal region and a large peak in the occipital region, but total power was greater in the quiet sleep. Total power decreased with increasing conceptional age. Topographic pattern discrimination between different conceptional age groups showed significant differences mainly in the frontal, temporal and occipital regions. It was concluded that regional differences in the development of EEG in premature infants could be clarified by means of topographic EEG analysis and the pattern discrimination method using the autoregressive model.

An application of autoregressive model to pattern discrimination of brain electrical activity mapping.

Using the autoregressive model, we developed a method of illustrating significant regional differences between two records of brain electrical activity mapping. This new approach of brain electrical activity mapping analysis through a statistical taxonomy may be clinically useful for evaluation of the normal development of EEG in children and for localizing functional brain abnormality.

Cardio-respiratory control in an infant with Ondine's curse: a multivariate autoregressive modelling approach.

We applied spectral analysis through multivariant autoregressive model fitting [1] to RR interval (RRI) and respiratory (RES) oscillation obtained during quiet sleep in an infant with congenital central hypoventilation syndrome (Ondine's curse), a child with obstructive sleep apnea, and two healthy children. Power spectra, impulse response and noise contribution ratio between RRI and RES oscillation were calculated by using a minicomputer PFU-1200 (FACOM) to determine the structure of the feedback system between RRI and RES within the central nervous system. We found that the respiratory noise contribution ratio to RRI was significantly smaller in Ondine's curse (37 +/- 7.7%, at 0.23 Hz) than in obstructive sleep apnea (90 +/- 6.7%, at 0.39 Hz) and healthy subjects. We postulate that the result shows disturbance of the central autonomic control of breathing and heart rate in Ondine's curse.

Oxidative stress in newborn infants with and without asphyxia as measured by plasma antioxidants and free fatty acids.

A rapid perfusion of oxygen in infants at birth may cause an increase of oxidative stress. To assess this possibility, we measured levels of blood plasma antioxidants and free fatty acids in 20 normal infants at 0, 1, 3, and 5 days after birth. Plasma levels of the most reactive antioxidant, ascorbic acid, decreased daily to equilibrium values at days 3 and 5. Percentages of oxidized form of coenzyme Q-10 (%CoQ-10) in total coenzyme Q, another good marker of oxidative stress, in infants (25-31%) were significantly higher than those in healthy young adults (4.5%). Plasma levels of total free fatty acids (FFA) in normal infants were highest at day 1 and decreased rapidly thereafter. The content of polyunsaturated fatty acids (PUFA) in total FFA was lowest at day 1 and then increased. Since PUFA are susceptible to oxidation, these changes in FFA composition suggest that oxidative stress is most evident at the initial day of neonatal life. Furthermore, it appears that mono-unsaturated fatty acids such as oleic and palmitoleic acids increase in response to the oxidative loss of PUFA. Similar changes in plasma antioxidants, FFA levels, and FFA compositions were observed in 9 infants with asphyxia. Values of %CoQ-10 in infants with asphyxia were significantly greater than those in normal infants, suggesting that infants with asphyxia have elevated oxidative stress.

[A case of surgically treated newborn with congenital tracheal stenosis].

This is a case report of a newborn with congenital tracheal stenosis which was fortunately healed by surgery. A 2,650 g female infant was born at 39 wk gestation. She began having respiratory difficulty soon after birth. Prompt endotracheal intubation was attempted, but failed. She was transferred to our hospital under assisted ventilation. Chest roentgenogram and bronchoscopy demonstrated segmental narrowing of the trachea about 2 cm distal from the vocal cord. A surgical operation was performed because respiratory management would not be enough to save the infant. Through a transverse collar incision and an upper median sternotomy, a stenotic 7 mm length of the trachea was resected and anastomosed with 5-0 Dexon suture. Postoperative course was uneventful. Histologically, the stenotic segment consisted of hypoplasia of the tracheal cartilage and fibrosis of the membranous portion. Squamous metaplasia was also recognized. There was no other report of tracheal stenosis successfully operated during the period of newborn.

Delayed increase in neuronal nitric oxide synthase immunoreactivity in thalamus and other brain regions after hypoxic-ischemic injury in neonatal rats.

We examined the response of neuronal nitric oxide synthase (nNOS)-containing CNS neurons in rats exposed to a unilateral hypoxic-ischemic insult at 7 days of age. Animals were sacrificed at several time points after the injury, up to and including 7 days (Postnatal Day 14). Brain regions ipsilateral to the injury (including cerebral cortex, caudate-putamen, and thalamus) exhibited delayed, focal increases in nNOS immunoreactivity. The increase in nNOS immunoreactive fiber staining was prominent in areas adjacent to severe neuronal damage, especially in the cortex and the thalamus, regions that are also heavily and focally injured in term human neonates with hypoxic-ischemic encephalopathy. In cerebral cortex, these increases occurred despite modest declines in nNOS catalytic activity and protein levels. Proliferation of surviving nNOS immunoreactive fibers highlights regions of selective vulnerability to hypoxic-ischemic insult in the neonatal brain and may also contribute to plasticity of neuronal circuitry during recovery.