Biomedical subjects

Yasuhiro Kikuchi

Publications and source records attributed to Yasuhiro Kikuchi.

8 recordsLinked to original sources

PubMed2005

Optic nerve evoked potentials elicited by electrical stimulation.

This study investigated whether the optic nerve evoked potential (ONEP) elicited by electrical stimulation of the optic nerve can serve as a reliable intraoperative indicator of visual function. In the experimental study, two silver-ball stimulating electrodes were placed on the dog optic nerve adjacent to the apex of the orbit and one recording electrode was placed on the optic nerve near the chiasm. The nerve was stimulated with 0.1 to 10 mA rectangular pulses. Stable and reproducible ONEPs were obtained. The ONEPs were not influenced by electromyographic potentials and were recorded more clearly on the optic nerve than on the surrounding tissue. Stepwise incremental transection of the thickness of the nerve resulted in incremental amplitude reduction proportional to the transected area. No response was recorded after complete sectioning of the nerve. In the clinical study, recordings were obtained from 15 patients after craniotomy to treat parasellar tumors or cerebral aneurysms. Reproducible ONEPs were recorded intraoperatively from the electrode placed on the optic nerve near the chiasm in 14 of 15 patients. In the remaining patient, the ONEP, recorded only after tumor removal because the optic nerve was stretched and extremely thin, was remarkably small and the patient developed unilateral blindness postoperatively. These experimental and clinical results suggest the possibility of intraoperative monitoring of visual function in patients undergoing craniotomy for the treatment of lesions near the optic nerve.

Adult↗

PubMed2005

[Significance of shunt efficacy decision of SPECT on idiopathic normal pressure hydrocephalus].

PURPOSE: The purpose of this study was to investigate the significance of the shunt-effect evaluation of SPECT in idiopathic normal pressure hydrocephalus (iNPH). SUBJECTS AND METHODS: The subjects were 15 patients with possible iNPH, aged 62-83 (mean 75.3, the ratio of males to females to 6:9), who were treated at our department during the period from June to September, 2004. All patients received the lumbar tap test (LTT) at the outpatient section before surgery. An L-P shunt was conducted on patients whose the LTT positive or negative with cerebrospinal fluid outflow resistance value (Ro) was 10 mmHg/ml/min. or higher patients. As for SPECT, a 3D-SSP Z-score, as well as an mCBF, was conducted before and after the LTT and within one month after surgery. Comparisons were made for (1) the shunt effect, (2) mCBF before and after the LTT and after surgery, (3) mean cerebral blood flow increase rate (mIR) after the LTT, and (4) 3D-SSP before and after surgery. RESULTS: (1) The shunt was effective for all the patients. (2) The mCBF levels was 30.8 +/- 4.02 ml/100 g/min. before the LTT, 37.1 +/- 100 g/min. after the LTT, and 38.6 +/- 3.4 ml/100 g/min. after surgery. A significant increase in mCBF was observed both after the LTT and after surgery (p < 0.05). (3) The mean mIR after the LTT was 21.2 +/- 8.01%, with all the patients showing 10% or higher. (4) The ischemic patterns in the SD-SSP Z-score before surgery were the frontal type (F: 10 cases, 66.7%), the occipitotemporal type (OT: 3 cases, 20%), and the mixed type (M: 2 cases, 13.3%), but not the parietal localized type. The post-operative course showed no-change in 4 cases, disappearance-reduction in 9 cases, and shift to OT in 2 cases. CONCLUSION: The evaluation factors in the measurement of the cerebral blood flow for evaluation of the shunt effect were the following two items. (1) The mIR of mCBF after the LIT was 10% or higher. (2) As for the preoperative cerebral ischemic patterns, there were many F cases and no parietial localized types found.

Aged↗

PubMed2005

[Reinvestigation of CSF outflow resistance value in idiopathic normal pressure hydrocephalus--comparing epidural pressure monitoring with lumbar subarachnoid cerebrospinal fluid pressure monitoring].

PURPOSE: To compare the cerebrospinal fluid (CSF) outflow resistance values (Ro) with epidural pressure (EDP) monitoring and lumbar subarachnoid CSF pressure (L-CSFP) monitoring. SUBJECTS AND METHODS: The subjects were 14 patients with possible iNPH (age: 59-74 years old, ratio of male and female 8:6). All the patients were subjected to an infusion test by a single bolus injection method (1 ml/sec., deltaV: 5 ml, t2: 2 min) as prescribed in the Standard of SINPHONI. EDP was monitored by continuous monitoring and the L-CSFP values By intermittent simple glass tube method (SINPHONI) were measured simultaneously. The Ro (RoEDP, RoL-CSFP) calculated from both methods, (1) the correlation of Ro and (2) the Ro threshold in a shunt effective group (E: nine cases) and a non effective group (NE, five cases) were compared. RESULTS: (1) Although a favorable correlation was found between both Ro measurements (r=0.784), the RoEDP was always higher than the RoL-CSFP. (2) The mean Ro values in the E and NE groups were 36.8 +/- 15.7 mmHg/ml/min, and 10 +/- 2.05 mmHg/ml/min for Ro-EDP, 22.1 +/- 13.95 mmg/ml/min and 6.4 +/- 1.7 mmHg/ml/min for RoL-CSFP, respectively. The approximate thresholds in the E and NE groups were 15 mmHg/ml/min for RoEDP and 10 mmHg/ml/min for RoL-CSFP. CONCLUSION: (1) Although the RoEDP is always higher than the RoL-CSFP, a favorable correlation is found between the RoEDP and RoL-CSFP, (2) The Ro thresholds of the E and NE groups in the infusion test are about 15 mmHg/ml/min for RoEDP and 10 mmHg/ml/min for RoL-CSFP. (3) After this, Ro calculation ought to execute by standard of SINPHONI and the Ro threshold of the E and NE groups is about 10 mmHg/ml/min.

Aged↗

PubMed2003

Quantitative analyses of cross-sectional shape of the distal radius in three species of macaques.

I conducted quantitative analyses of the cross-sectional shape of the distal radial shaft in three species of macaques, which differ in locomotor behavior: semi-terrestrial Japanese macaques ( Macaca fuscata), arboreal long tailed macaques ( M. fascicularis), and relatively terrestrial rhesus macaques ( M. mulatta). I took CT scans of the distal radial shafts of a total of 180 specimens at the level of the inferior radio-ulnar articulation. From each CT image, the periosteal outline of the radius was traced automatically by a digital imaging technique. I determined five points (landmarks) on the outline by developing a standardized morphometric technique. Bone surface lengths were measured by using these landmarks and their soft tissue correlates were investigated. The results of this study were as follows: (1) Semi-terrestrial M. fuscata has features that are approximately intermediate between those of the other two species. M. fuscata has a relatively small groove for M. abductor pollicis longus and a large groove for Mm. extensor carpi radialis longus et brevis. These characters resemble those of M. fascicularis. On the other hand, the ulnar notch of M. fuscata is relatively large, a character which is similar to that of M. mulatta. Moreover, compared to the other two macaques, the surface of the flexor muscles of M. fuscata is intermediate in size. (2) The more terrestrial M. mulatta has a relatively large groove for M. abductor pollicis longus and a small groove for Mm. extensor carpi radialis longus et brevis. Moreover, M. mulatta has a relatively large ulnar notch and a small surface for the flexor muscles. (3) The arboreal M. fascicularis has similar features to those of M. fuscata for the first and second relative size index. However, in the ulnar notch, M. fascicularis has a peculiar character and the surface for the flexor muscles is relatively large compared to those of the other two species. These results can be interpreted in terms of positional habits and presumed functional demands. A form-functional study by Lemelin and Schmitt also corroborates the interpretations of the present study. Thus, the distal region of the forearm strongly reflects muscular development and joint resultant force, and is an important region for investigating locomotor adaptations in primates. The present study reveals the possibility of using this type of morphometric analysis for reconstructing the positional behavior of fossil primates.

Animals↗

PubMed2003

A longitudinal study on hand and wrist skeletal maturation in chimpanzees ( Pan troglodytes), with emphasis on growth in linear dimensions.

Skeletal maturation in the chimpanzee hand and wrist (the RUS system; radius, ulna, and short bones) was studied both longitudinally and cross-sectionally. Maturity states were evaluated in each of the 13 bones of the RUS system based on the TW2 method (Tanner and Whitehouse method), and the RUS score was calculated by the summation of scores for these bones. Individual variation was examined by means of residual curves and pseudo-velocity curves of RUS score and anterior trunk length (ATL). Norms of the age change pattern in RUS skeletal maturation and the growth of ATL were determined for each sex, and the relationships among ATL growth and skeletal and reproductive maturation were examined. We found a fairly good relationship between ATL growth and RUS skeletal maturation. Comparison of growth and development between humans and chimpanzees showed that growth characteristics are coupled with each other at puberty in male chimpanzees and in both sexes of humans. Although nutritional condition influenced ATL growth in infancy, it had no effect on the RUS maturational process. Social relationships appeared to influence both ATL growth and RUS maturation. Analyses on relationships between RUS skeletal maturation, ATL growth, and reproductive maturation, showed that RUS skeletal maturation is a good indicator of "physiological age".

Age Determination by Skeleton↗

PubMed2003

Bone mineral density in chimpanzees, humans, and Japanese macaques.

We performed a comparative study of bone mechanical properties in the radii of chimpanzees (Pan troglodytes), humans (Homo sapiens), and Japanese macaques (Macaca fuscata) using peripheral quantitative computed tomography. We investigated: (1)cortical bone area relative to the total periosteal area (PrA); (2) trabecular bone area relative to PrA; (3) cortical bone density; and (4) trabecular bone density. The cortical bone area index for chimpanzees was almost the same as that of Japanese macaques, whereas the equivalent value in humans was about the two-fifths that of the others. Values for the other three properties were constant among these three catarrhine species. Chimpanzees do not particularly resemble humans, but are more similar to digitigrade macaques in terms of bone properties. The constant trabecular bone area index and trabecular density value in these species may suggest that a certain amount of trabecular bone (20-30% of total bone area at the distal 4% level of the forearm) is necessary to achieve normal bone turnover. The physiological metabolism of bone, including cortical bone density, might be conserved in these catarrhines.

Animals↗

PubMed2003

Selective accumulation of delphinidin derivatives in tobacco using a putative flavonoid 3',5'-hydroxylase cDNA from Campanula medium.

Blue flowers generally contain 3',5'-hydroxylated anthocyanins (delphinidin derivatives) as pigments, which are formed only in the presence of flavonoid 3',5'-hydroxylases (F3'5'H). Heterologous expression of a F3'5'H gene therefore provides an opportunity to produce novel blue flowers for a number of ornamental plants missing blue flowering varieties. However, our previous study indicated difficulties in obtaining good accumulation of delphinidin derivatives in plants expressing F3'5'H. Here we report the isolation of a putative F3'5'H cDNA (Ka1) from canterbury bells (Campanula medium) and its expression in tobacco. Surprisingly, compared with other F3'5'H cDNAs, Ka1 encoded a protein with a unique primary structure that conferred high competence in the accumulation of delphinidin derivatives (up to 99% of total anthocyanins) and produced novel purple flowers. These results suggest that, among F3'5' H cDNAs, Ka1 is the best genetic resource for the creation of fine blue flowers by genetic engineering.

Anthocyanins↗

PubMedDate not supplied

Multifocal visual evoked potential is dependent on electrode position.

PURPOSE: To investigate whether the multifocal visual evoked potential (mVEP) is dependent on the electrode position, and to confirm the reproducibility of the mVEP. METHODS: The mVEPs were recorded using the Veris III system with two different bipolar electrode settings. In Position 1, electrodes were placed at equal distances in vertical alignment 2 cm above and below the inion. In Position 2, the electrodes were placed in horizontal alignment at equal distances 2 cm to the left and right of the inion. Dartboard pattern stimulation was conducted. The mVEPs were repeatedly recorded from 4 volunteers, and mainly the second-order kernel response components were analyzed. RESULTS: Although the reproducibility of mVEP was good in both Position 1 and Position 2, each waveform of the mVEP was drastically different between the two positions. This difference in the waveforms was clearly shown in the center and at the horizontal meridian. We also investigated the first-order kernel response components of the mVEPs. Several traces of the first-order kernel response components did not reveal flat traces. This point is also worthy of consideration. CONCLUSION: Responses from mVEPs are clearly dependent on the electrode position.

Adult↗