Kazuna Sugiyama

A Morphological Analysis of Thalamocortical Axon Fibers of Rat Posterior Thalamic Nuclei: A Single Neuron Tracing Study with Viral Vectors

The rostral sector of the posterior thalamic nuclei (POm) is, together with the ventral posterior nuclei (VP), involved in somatosensory information processing in rodents. The POm receives inputs from the spinal cord and trigeminal nuclei and projects to the primary somatosensory (S1) cortex and other cortical areas. Although thalamocortical axons of single VP neurons are well known to innervate layer (L) 4 of the S1 cortex with distinct columnar organization, those of POm neurons have not been elucidated yet. In the present study, we investigated complete axonal and dendritic arborizations of single POm neurons in rats by visualizing the processes with Sindbis viruses expressing membrane-targeted fluorescent protein. When we divided the POm into anterior and posterior parts according to calbindin immunoreactivity, dendrites of posterior POm neurons were wider but less numerous than those of anterior neurons. More interestingly, axon fibers of anterior POm neurons were preferentially distributed in L5 of the S1 cortex, whereas those of posterior neurons were principally spread in L1 with wider and sparser arborization than those of anterior neurons. These results suggest that the POm is functionally segregated into anterior and posterior parts and that the 2 parts may play different roles in somatosensory information processing.

Displacement of the Endotracheal Tube Caused by Change of Head Position in Pediatric Anesthesia: Evaluation by Fiberoptic Bronchoscopy

Displacement of the endotracheal tube (ETT) caused by flexion and extension of the neck and the placement of a tongue depressor was investigated in 10 small children between the ages of 16 and 19 mo by means of a fiberoptic bronchoscope.The ETT tip moved a mean distance of 0.9 cm toward the carina with flexion and 1.7 cm toward the vocal cords with extension of the neck. After the placement of a tongue depressor, the ETT tip, which had once moved toward the vocal cords with neck extension, was displaced a mean distance of 1.2 cm toward the carina. Our results demonstrate that endobronchial intubation and accidental extubation could occur after significant changes of the head position and careless placement of a tongue depressor in small children. (Anesth Analg 1996;82:251-3)

Effects of ketamine on dopamine metabolism during anesthesia in discrete brain regions in mice: comparison with the effects during the recovery and subanesthetic phases

The effects of ketamine on the levels of dopamine (DA), norepinephrine (NE), 5-hydroxytryptamine (5-HT, serotonin) and their metabolites were examined in discrete brain regions in mice. A high dose of ketamine (150 mg/kg, i.p.) did not change DA metabolism in the frontal cortex, nucleus accumbens, striatum and hippocampus, but did decrease it in the brainstem during anesthesia. In contrast, during recovery from the ketamine anesthesia, the high dose increased the level of homovanillic acid (HVA) in all brain regions. A low subanesthetic dose of ketamine (30 mg/kg, i.p.) increased the concentrations of both 3,4-dihydroxyphenylacetic acid (DOPAC) and HVA only in the nucleus accumbens. The DA level was not affected by any ketamine treatment. During ketamine anesthesia, the content of 3-methoxy-4-hydroxy-phenylglycol (MHPG) was decreased in the brainstem, whereas during recovery from anesthesia, the MHPG level was increased in the frontal cortex, nucleus accumbens and brainstem. The NE content was not altered in any region by ketamine treatment. The concentration of 5-hydroxyindoleacetic acid (5-HIAA) was reduced in the frontal cortex, striatum, hippocampus and brainstem during ketamine anesthesia. The 5-HT level was unaltered in all regions except the brainstem where it was reduced. In contrast, after anesthesia, the concentrations of both 5-HT and 5-HIAA were increased in the striatum. During the subanesthetic phase, however, the levels of NE, 5-HT and their metabolites were unchanged. These neurochemical results are consistent with the electrophysiological findings that a high dose of ketamine does not change the basal firing rates of nigrostriatal DA neurons during anesthesia, while low subanesthetic doses significantly increase those of ventral tegmental DA neurons.

Does the Murphy eye reduce the reliability of chest auscultation in detecting endobronchial intubation

UNLABELLED Bilateral breath sounds are routinely auscultated after endotracheal intubation to verify that the endotracheal tube (ETT) tip is properly positioned. We conducted the present study to ascertain whether the eye of the Murphy tube has an influence on the reliability of auscultation of breath sounds in detecting endobronchial intubation. Twenty patients undergoing scheduled oral and maxillofacial surgery participated in this study. After the induction of general anesthesia, either the Magill tube or the Murphy tube was inserted through the nose into the trachea. The fiberoptic bronchoscope was inserted through the ETT, and the distance from the nares to the carina of the trachea was measured. When breath sounds from the left side of the chest changed and disappeared while the ETT was being advanced, the distance from the nares to the ETT tip was measured. Unilateral auscultatory change was not observed until the ETT tip was advanced beyond the carina and inserted 1.5+/-0.4 cm into the right mainstem bronchus when the Magill tube was used and 2.0+/-0.4 cm when the Murphy tube was used (P < 0.01). Breath sounds disappeared when the ETT tip was further advanced up to 3.2+/-0.3 cm from the carina. We demonstrated that the eye of the Murphy tube reduces the reliability of chest auscultation in detecting endobronchial intubation. IMPLICATIONS The Murphy eye was designed to allow ventilation of the lung when the bevel of the endotracheal tube is occluded. We demonstrated that the eye of the Murphy tube reduces the reliability of chest auscultation in detecting endobronchial intubation.

Temporomandibular joint pain analgesia by linearly polarized near-infrared irradiation.

Objective: The objective of this study was to describe a pilot treatment of temporomandibular joint pain by linearly polarized near-infrared irradiation. Design: A prospective clinical study. Setting: University teaching hospital. Patients: Patients comprised 20 women (mean age ±SD: 26.6 ± 15.2 years) with unilateral temporomandibular pain. The patients had already received other conservative treatments, but temporomandibular pain did not attenuate. Intervention: Linearly polarized near-infrared irradiation with the Super Lizer was used. Results: The painless interincisal distance of the mouth opening, which is one of the objective parameters of temporomandibular dysfunction, and the visual analogue scale of the affected temporomandibular joint before treatment were 33.4 ± 6.5 mm and 5.0 ± 2.7 points, respectively. Pilot linearly polarized near-infrared irradiation was applied weekly to the skin areas overlying four painful points. The present treatment alleviated temporomandibular pain after the patients had received only four weekly irradiation treatments, with final measured values of the visual analogue scale being 1.4 ± 1.6 points. The final painless mouth-opening distance increased by 7.6 ± 4.6 mm compared with the first measured distance without complications. Conclusion: This pilot treatment using the Super Lizer provided relief from temporomandibular pain over a period of 4 weeks.

Sizes and depths of endotracheal tubes for cleft lip and palate children undergoing primary cheiloplasty and palatoplasty

Background:  Appropriate sizes (internal diameters) and insertion depths of uncuffed preformed endotracheal tubes in children with cleft lip and palate, who generally have delayed growth and development in early infancy have not been elucidated.

Inhalational conscious sedation with nitrous oxide enhances the cardiac parasympathetic component of heart rate variability

OBJECTIVE We investigated the effects of conscious sedation by 30% nitrous oxide inhalation on the cardiac autonomic nervous system in the absence or presence of music listening. STUDY DESIGN The power spectral analysis of heart rate variability (HRV) and cardiovascular parameters were measured in 26 healthy volunteers, who were divided into the control and N(2)O groups. RESULTS Nitrous oxide inhalation attenuated the increase in relative low frequency (LF) power in the control group, but relative high frequency (HF) power remained constant compared to a decreased value in the control group. Nitrous oxide inhibited the increase in the LF/HF ratio. These autonomic balance shifts were observed without hemodynamic changes. Additional music during sedation did not alter HRV variables. CONCLUSIONS Inhalational sedation with nitrous oxide shifted cardiac sympathetic-parasympathetic balance toward a parasympathetic dominance via the suppression of sympathetic activity. Music listening during sedation did not provide further relaxing effects.

Influence of Linearly Polarized Near-Infrared Irradiation on Deformability of Human Stored Erythrocytes

OBJECTIVE To investigate the influence of linearly polarized near-infrared irradiation using the Super Lizer trade mark on deformability of human erythrocytes. BACKGROUND DATA Not only low-powered laser but also linearly polarized near-infrared beams have some biostimulation effects on various tissues. There were some reports of erythrocyte deformability improved by low-powered He-Ne laser irradiation. MATERIALS AND METHODS Human erythrocyte samples stored for three weeks were adjusted to 30% hematocrit. Erythrocyte deformability presented as the filter filtration rate was measured. RESULTS There was no difference of the filter filtration rate between control group without irradiation and the group of 125 mJ/cm(2) exposure level at a wavelength of 830 nm. However, the groups of 625 and 1,250 mJ/cm(2) exposure levels at a wavelength of 830 nm showed higher filter filtration rates compared to the control group. CONCLUSION Linearly polarized near-infrared irradiation in a range of 625-1,250 mJ/cm(2) exposure level at a wavelength of 830 nm improved deformability of human stored erythrocytes.

Dexmedetomidine dose-dependently enhances local anesthetic action of lidocaine.

PURPOSE The combination of α2-adrenoceptor agonists, such as dexmedetomidine (DEX) and clonidine, with local anesthetics has been found to extend the duration of peripheral nerve blocks, probably owing to the resultant local vasoconstriction in the peripheral nerves. However, because the clear elucidation of the effect of DEX requires examination of the local anesthetic effect with DEX alone and the combination of various concentrations of DEX with local anesthetics, we evaluated the local anesthetic effect of various concentrations of DEX alone and with a local anesthetic. MATERIALS AND METHODS The present study assessed the tail-flick (TF) latencies after injection of the appropriate drug in male Sprague-Dawley rats, using an epidural model that allowed constant pain stimulation intensity, dispersion of the anesthetic, and a precise injection site and dose. Lidocaine alone, lidocaine with 2.5-ppm DEX, lidocaine with 5.0-ppm DEX, lidocaine with 7.5-ppm DEX, and DEX alone were administered at the predetermined dose. The TF latency changes over time were compared using repeated measures analysis of variance (ANOVA). Comparisons among the groups were analyzed using ANOVA followed by a post hoc Dunnetts multiple comparison test or Tukeys multiple comparison test. RESULTS The addition of DEX to lidocaine increased the TF latency and dose-dependently prolonged its duration as follows: 0-ppm DEX, 20 minutes; 2.5-ppm, 40 minutes; 5.0-ppm, 40 minutes; and 7.5-ppm, 50 minutes. DEX alone did not change the TF latency. CONCLUSIONS Our results have demonstrated that DEX dose-dependently enhances the local anesthetic action of lidocaine in a rat TF model.

Difficult Intubation in a Patient Without a Mandibular Body

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