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Biomedical subjects

A Ikeda

Publications and source records attributed to A Ikeda.

At least 19 recordsLinked to original sources
PubMed1992

A new look at the blood supply of the retro-ocular space. Three-dimensional analysis of the arterial pattern of the posterior ciliary artery.

A study of the arterial architecture of the orbit, especially the ophthalmic artery and the course of the posterior ciliary artery in the retroocular space, was carried out in 198 cadavers by three-dimensional arteriographic analysis. The posterior ciliary arteries were classified into three types: lateral posterior ciliary, medial posterior ciliary, and accessory posterior ciliary arteries. Both the lateral and medial posterior ciliary arteries reach the eyeball in three ways: (1) they run antero-inferiorly in a winding course to the posterior margin of the eyeball, then shift upward vertically at a 60-90 degree angle and reach the eyeball, where they divide into several ciliary branches (69%); (2) after a similar course, others branch to the eyeball from the superior side (29.3%); or (3) they reach the eyeball in an almost straight course along the optic nerve (1.7%). The fundamental characteristics of these three types of posterior ciliary artery pattern also exist in subhuman primates.

Adult↗
PubMed1992

Automatic EEG interpretation: a new computer-assisted system for the automatic integrative interpretation of awake background EEG.

A new computer-assisted system for automatic interpretation of the awake electroencephalogram (EEG) was developed. First, all the items necessary for EEG interpretation were determined in accordance with the procedure that a qualified electroencephalographer (EEGer) goes through for the visual inspection of the background EEG activity, and then each item was defined quantitatively. For the automatic interpretation, specific EEG parameters were determined for each item so that they could fit the graded judgement of the item by the qualified EEGer as closely as possible. These specific EEG parameters were actually calculated from periodograms obtained from the time series of EEG records of 14 patients with various neurological diseases. The automatic EEG interpretation system thus established was applied to the EEG data of these 14 subjects and to 3 additional EEGs, and the results were compared with those obtained through the visual interpretation by the EEGer. This automatic EEG interpretation was found to be in good agreement with the visual interpretation by the EEGer in most EEG records. In contrast with the previous automatic analyses of EEG which were focussed on certain aspects of EEG such as the dominant rhythm, the present system is unique in its capability of providing an integrative interpretation of the spontaneous awake EEG by taking into account all its features except for paroxysmal abnormalities.

Adult↗
PubMed1992

Movement-related potentials recorded from supplementary motor area and primary motor area. Role of supplementary motor area in voluntary movements.

Movement-related potentials (MRPs) were recorded from subdural electrodes chronically implanted in the interhemispheric fissure in two patients being evaluated for epilepsy surgery. Different types of movements (finger, foot, tongue and vocalization) were executed. Foot movements elicited a clearly defined, well-localized slow negativity or positivity (Bereitschaftspotential, BP) preceding electromyogram (EMG) onset. These BPs were seen from the contralateral primary motor foot area and also from bilateral supplementary motor areas (SMAs) with equivalent amplitudes and temporal evolutions. A steeper potential [negative slope (NS')] occurred about 300 ms before EMG onset and the motor potential (MP) started 100 ms before EMG onset. Negative slopes and MPs also arose from the contralateral primary motor area as well as from the bilateral SMAs. Finger movements elicited well-localized BPs and NS' which were generated from the bilateral SMAs, but were of higher amplitude on the contralateral SMA. Motor potentials started 50 ms prior to EMG onset and arose exclusively from the contralateral SMA. Tongue protrusions and vocalizations also elicited BP, NS' and MP which were seen in the bilateral SMAs. Movement-related potentials for different types of movements had a somatotopic distribution in the SMA, which was consistent with the SMA somatotopic organization defined by electrical simulation. Movement-related potentials for tongue movements and vocalization had a similar distribution and waveform. It was concluded that bilateral SMAs generate well-defined MRPs consistent with the assumption that the SMA plays a significant role in the organization of voluntary movements. However, the MRPs from the bilateral SMAs do not have characteristics which are different from those of the primary motor area. This suggests the hypothesis of 'supplementary' function for SMA, and does not support the hypothesis of 'supramotor' function.

Adolescent↗
PubMed1992

Invasive recording of movement-related cortical potentials in humans.

Movement-related cortical potentials (MRCPs), especially the premovement components seen only in association with voluntary movements, may represent the higher brain functions related to preparation for voluntary movements. Recent advances in many aspects (single unit and field potential recordings in animals, intracranial recording of MRCPs in epileptic patients, magnetoencephalography, and positron emission tomography) have provided new information about the physiological significance of MRCPs. In contrast to the findings on scalp recordings, in which the early potentials prior to movement onset are seen more widely, the main cortical generators appear to be discretely localized in bilateral primary and supplementary motor areas with a contralateral predominance. This review outlines the findings in scalp-recorded MRCPs and compares them with the results of invasive recordings, paying special attention to their physiological significance.

Animals↗
PubMed1992

The vasculature and clinical application of the posterior tibial perforator-based flap.

Use of the posterior tibial flap pedicled on the posterior tibial vessels has been described by several authors, but with it there is the major disadvantage of an unavoidable transection of the posterior tibial artery. To overcome this disadvantage, we anatomically studied the perforators from the posterior tibial artery and used posterior tibial perforator-based flaps clinically. Based on our anatomic study of 25 cadaveric legs, the cutaneous perforators were considered to be distributed from the distal to the proximal sides of the lower leg through the medial border of the tibia, and they were classified into three types: septocutaneous perforators mainly located in the distal third of the leg, muscle perforators located in the proximal half, and periosteal perforators in the proximal third of the leg. The average size and number of perforators was 0.8 mm and 3.1 in one leg, respectively. A considerable number were located at sites from 70 to 140 mm superior to the medial malleolus. Based on our clinical cases repaired with flaps, we consider this flap to be useful as a free flap for the repair of defects of the extremities and as an island flap for reconstruction of defects on the anteromedial aspect of the lower leg. The territory of the flap is relatively wide, being 19 x 13 cm. The long saphenous vein can be used safely as the venous drainage system in the case of free-flap transfer.

Adult↗
PubMed1992

Intracranial paramedian hourglass-shaped dermoid associated with hereditary steatocystoma multiplex.

This is the first report to describe the coexistence of two rare diseases, intracranial paramedian hourglass-shaped dermoid and steatocystoma multiplex. A 46-year-old female with a history of steatocystoma multiplex, bradydactylies and kyphosis showed oscillopsia, ataxia and hemifacial spasm. MRI findings suggested a giant dermoid cyst extending from the left middle temporal fossa to the cerebellopontine angle, and this was confirmed surgically. We propose the involvement of some genetic factor or pathological process common to both disorders, steatocystoma multiplex and dermoid. From the clinical point of view, patients with cystic skin lesion should also be checked for intracranial lesion.

Brain Neoplasms↗
PubMed1992

[Difference between horizontal enlargement and vertical enlargement of the internal auditory meatus in acoustic neuroma].

Twenty-one patients with acoustic neuroma were investigated. The vertical diameter of the internal auditory meatus was measured by polytomography, the horizontal by target imaging CT. The ratio of the abnormal side to the normal side was calculated in each dimension. Two dimensional ratios were compared with each other in order to investigate the difference between horizontal and vertical enlargement of the internal auditory meatus. The results were as follows: 1) Horizontal enlargement of the internal auditory meatus was greater than that of the vertical one in 15 cases (75%). Vertical enlargement was greater in 6 cases but the difference between the two dimensions was not significant. 2) With horizontal enlargement, the posterior wall of the internal auditory meatus was more extended or destroyed than that of anterior wall. 3) With enlargement of the posterior wall, the bony eminence forming the inner side of the porus was predominantly extended or destroyed in every case.

Adolescent↗
PubMed1992

[Craniotomy for lesions in the cerebral convexity; how to precisely localize the lesions with conventional CT slices].

A simple direct precise localization with a CT scan for convexity lesions is presented. The shape of the normal calvarium was analyzed and a characteristic pattern was obtained, that is, one spherical surface in the frontal area and 6 flat planes in the temporal, parietal and occipital areas. The temporal plane is perpendicular to the orbito-meatal line (OML), while the parietal plane declined 29 degrees in the A-P view, and the occipital plane declined 60 degrees in the lateral view. A summit of these three planes forming the parietal tubercle, and the crest following the tubercle between the parietal and occipital planes were detected either by CT scan, or by palpating the skull. Conventional methods of preoperative localization include measurement and calculation from the base line such as OML, or obtaining a CT scan with a marker on the scalp. The former might have an error that will be amplified in the parietal region that would not be negligible. The latter is a rather troublesome method demanding that the CT scan be taken after shaving the hair. Landmarks utilized for the localization should be identified both on the CT scan and on the scalp or skull. These involved OML, coronal suture, parietal tubercle, inion, pineal body, midline and so on. Of these, the coronal suture runs almost perpendicular to the OML and would be the best landmark for the localization in the parietal area.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain↗
PubMed1992

Intracranial arterial reconstructive surgery for unclippable aneurysms. An application of microvascular suturing.

Intracranial arterial reconstructive techniques were used in three patients for whom conventional neck clipping was not feasible due to the size, location or symptoms of their aneurysms. In the first case, complicated by subarachnoid hemorrhage, a giant aneurysm in the right middle cerebral artery was excised and the stump of the parent arteries was reconstructed in end-to-end and end-to-side fashion. The second case had a large thrombosed aneurysm in the left vertebral artery compressing the medulla oblongata, with small perforators originating from the proximal posterior inferior cerebellar artery (PICA) feeding the brainstem. The PICA was transposed to cerebellar cortical artery and the aneurysm excised. The third case presented with TIA and small infarctions were observed in the left thalamus. A giant, partially thrombosed, aneurysm in the left posterior cerebral artery (PCA) was trapped with a revascularization of the distal PCA from the superior cerebellar artery in side-to-side fashion. Indications for these intracranial arterial reconstructions in aneurysmal surgery were discussed and pertinent literature was reviewed.

Adolescent↗
PubMed1991

Studies on the generation of Ca2+/calmodulin-independent activity of calmodulin-dependent protein kinase II by autophosphorylation. Autothiophosphorylation of the enzyme.

The mechanism for the generation of the Ca2+/calmodulin (CaM)-independent activity of calmodulin-dependent protein kinase II (CaM-kinase II) by autophosphorylation was studied by characterizing the autothiophosphorylated enzyme, which is resistant to hydrolysis. When CaM-kinase II was incubated with adenosine 5'-O-(thiotriphosphate) at 5 degrees C, the incorporation of thiophosphate into the enzyme occurred rapidly, reaching a maximum level within a few minutes, in parallel with increase in Ca2+/CaM-independent activity. The maximum level was 1 mol of thiophosphate per mol of subunit of the enzyme, and the thiophosphorylation occurred exclusively at Thr286 in the alpha subunit and Thr287 in the other subunits of the enzyme. These results, taken together, indicate that the autothiophosphorylation of Thr286/Thr287 of each subunit is involved in the generation of the Ca2+/CaM-independent activity. The activity of the autothiophosphorylated enzyme, when assayed in the presence of Ca2+/CaM, showed the same kinetic properties as did the Ca2+/CaM-dependent activity of the original non-phosphorylated enzyme, but when assayed in the absence of Ca2+/CaM, it showed the same Vmax as the Ca2+/CaM-dependent activity but higher Km values for protein substrates. Thus, the phosphorylation of Thr286/Thr287 of the subunit of the enzyme by autophosphorylation appears to not only enhance the affinity of its substrate-binding site for the protein substrate, although it is lower than that of the enzyme activated by the binding of CaM, but also convert the active site to the fully active state.

Animals↗
PubMed1991

Scanning electron microscopy of the capillary loops in the dermal papillae of the hand in primates, including man.

The microvasculature of the skin of the hand in primates, including man, was examined by means of scanning electron microscopy of corrosion casts. In this study, the microvascular patterns and structures in different areas of the hand, and the changes in vascular patterns that occur with age, have been described. The typical structure of the capillary loops in the hand can be observed in the ball of the finger of the young adult monkey. The capillary loops were formed out of not just one capillary vessel, but two or three vessels. Each capillary vessel arose and divided into several branches at the papillae, and these became descending limbs. After the loop passed a hairpin turn, the descending limbs were 1.5 times larger than the ascending limbs in the intrapapillary portion, and they became extrapapillary venules. The descending limbs connected with the postcapillary venules in the postpapillary portion and with the horizontal network. The postcapillary venules fused with each other to form the primary and secondary venous arcades. The secondary venous arcades anastomosed with each other and flowed into the subpapillary venules, which run along the dermal furrow in the fingerprint. Changes in vascular patterns with age could be observed. In the infant fingerprint, the vascular systems had not yet differentiated, especially the venous system in the dermis. In the old adult finger, the capillary loops presented complicated features deviating due to aging.

Aged↗
PubMed1991

CO2 laser-induced pain-related somatosensory evoked potentials in peripheral neuropathies: correlation between electrophysiological and histopathological findings.

Pain-related somatosensory evoked potentials (pain SEPs) following CO2 laser stimulation as well as conventional electrically stimulated SEPs (electric SEPs) were examined in 10 patients with peripheral neuropathies in whom the histopathological examination of the sural nerve was done. Results of pain SEPs showed a positive relationship with clinical impairment of pain sensation and densities of small myelinated fibers of the sural nerve. In contrast, results of electric SEPs showed a positive relationship with clinical impairment of deep and tactile sensations and with densities of large myelinated fibers of the sural nerve. Therefore, pain SEPs are considered to be generated by ascending signals mediated through nociceptive receptors and A delta fibers. The pain SEP is only one noninvasive and objective method currently available to investigate a physiological condition of the sensory pathway responsible for pain sense, and is especially useful when combined with the conventional electric SEPs.

Adolescent↗
PubMed1991

Treatment of HTLV-I-associated myelopathy with high-dose intravenous gammaglobulin.

Fourteen patients with HTLV-1-associated myelopathy were treated with high-dose intravenous gammaglobulin (IVGG). Ten received 10 g/day of IVGG and 4 received 400 mg/kg of body-weight/day of IVGG for 5 consecutive days. Improvement of spastic paraparesis was observed in 10 within 7 days of the commencement of IVGG. The therapeutic effects were sustained for more than 3 weeks in some patients. There were no side effects. Analysis of factors of relevance to the clinical improvement with IVGG showed that the beneficial response was preferentially found in patients having a high CSF titre of anti-HTLV-I antibodies, a high CSF IgG level and a marked brain MRI abnormality.

Adult↗
PubMed1991

Scalp topography of giant SEP and pre-myoclonus spike in cortical reflex myoclonus.

Scalp topography of the giant SEP and the pre-myoclonus spike demonstrated by jerk-locked back averaging was studied by using a computer-assisted evoked potential mapping technique in 5 patients with cortical reflex myoclonus. The initial positive peak of giant SEP was localized to the postcentral region contralateral to the stimulus and was associated with a negative potential field of the same latency at the frontal region in all cases. The main positive peak of pre-myoclonus spike was localized to the postcentral region contralateral to the myoclonus in 4 cases, and maximal at the midline postcentral region extending contralaterally with respect to the myoclonus in 1 case. The postcentral positive peak was associated with a frontal negativity in 2 of the 5 cases. In those 2 cases, the main components of giant SEP and the pre-myoclonus spike showed a similar scalp distribution with respect to the hand which was stimulated or myoclonic jerks were recorded from, although the latter was much smaller and less sharp than the former. These findings support our previous hypothesis that those 2 activities might be generated, at least in part, by common physiological mechanisms. In 3 other cases, however, the postcentral positive peak of the pre-myoclonus spike was not associated with a frontal negativity.

Action Potentials↗
PubMed1991

Clinical long-term results of anterior discectomy without interbody fusion for cervical disc disease.

There were 55 patients (soft disc, 21 and spondylosis, 34) who underwent anterior cervical discectomy without fusion (ACD) using an operating microscope. Discectomy of a single level was performed on 48 cases and two levels on 7. There were 37 patients with radiculopathy, and 18 patients with myelopathy or myeloradiculopathy who were followed clinically for 2-13 years postoperatively. Overall 81% of patients were improved in soft disc herniation, and no significant differences were noted between the group of radiculopathy and myelopathy. In spondylosis all but one patient reported initial relief of their preoperative symptoms; however, overall improvement was noted in only 16 patients (47%). The causes of symptomatic deterioration after ACD for spondylosis were later symptomatic recurrence in 5 patients, severe neck pain in 4, and development of new symptoms due to adjacent spur formation in 2. The authors eventually added interbody fusion in 4 cases. Cervical spine roentgenograms almost always showed a loss of height of the interspace and an anterior angulation immediately after ACD, but the alignment of the spine tended to improve with time, so that, at last follow-up, 82% had a good alignment. A spontaneous osseous fusion occurred in 74% of cases. An adjacent spur formation was observed in 3 patients with spondylosis. The most troublesome complication was neck and/or scapular pain. This pain usually subsided spontaneously, but this continued for more than 4 years postoperatively in 4 patients with spondylosis. Using an operating microscope ACD is a safe and effective procedure for patients with soft disc herniation, but the authors still prefer anterior cervical discectomy with interbody fusion for the patients with advanced spondylosis.

Cervical Vertebrae↗
PubMed1991

A testicular teratoma with rhabdomyosarcoma and seminoma.

A case of testicular mixed germ cell tumor with teratoma in a 36-year-old Japanese male is reported. Histologically, it was strongly suggested that the rhabdomyosarcoma had originated from the mesenchymal element of the teratoma. A review of the literature revealed six definitive and two possible previous cases of testicular rhabdomyosarcoma with teratoma, either with or without other germ cell malignancies. However, the present case associated with seminoma as a germ cell tumor is the first of its kind to be reported. In contrast to the poor prognosis observed in the previous cases, the present patient remains free of disease 3 years and 3 months after orchiectomy, chemotherapy and irradiation.

Adult↗
PubMed1991

A new classification of the brachial extensors in Tarsius.

The muscular system of the tarsier was first described by Burmeister (1846), who noted that brachial extensors (triceps complex) have six heads. The first three heads, respectively, correspond to the long, lateral and medial heads of the triceps brachii muscle in man. The fourth head is the anconaeus and the fifth is the dorsoepitrochlearis. Schultz (1984) divided the sixth head into two different parts (preaxial and postaxial) from the viewpoint of nerve supply. The present study found that the whole sixth head is innervated by the ulnar nerve, and we propose that it is recognized as the proximal and distal heads of the (preaxial) epitrochleoanconaeus muscle. The proximal head may have developed specially in the tarsier in addition to the distal head observed in other prosimians. It is thought to support the extension of the elbow joint and contribute to the tarsier's effective locomotion.

Animals↗