Biomedical subjects
Publications and source records attributed to Y Tamai.
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The corticocortical connections of the frontal 'oculomotor' areas related to eye movements of the cat were studied using the retrograde horseradish peroxidase (HRP) tracing method combined with electrophysiological techniques. The following results were obtained. (1) The medial wall of the hemisphere under the cruciate sulcus (CRU), where contralateral conjugate eye deviation was elicited, received fibers from the medial bank of the presylvian sulcus (PRE). The fundus of the coronal sulcus (COR), where monocular movement of the contralateral eye was evoked, received fibers from the lateral bank of the PRE. (2) All the frontal oculomotor areas, the medial wall of the hemisphere under the CRU, the fundus of the COR, and both banks of the PRE, received fibers from the ipsilateral ventral bank of the anterior ectosylvian sulcus (AES). (3) The ventral bank of the AES received fibers from the caudal part of the lateral suprasylvian visual areas. On the basis of the fiber connections, the frontal oculomotor areas can be subdivided into a 'medial' area, the medial wall of the hemisphere under the CRU and the medial bank of the PRE, and a 'lateral' area, the lateral bank of the PRE and the fundus of the COR. Moreover, we found evidence of fiber projections from the ventral bank of the AES to the frontal oculomotor areas that were physiologically identified.
To study the types of the monocular eye movements, intracortical microstimulations were applied to the fundus of the cat's coronal sulcus where the monocular movements of the contralateral eye were evoked. The monocular eye movements were saccadic and directed toward the nasal side converging on a horizontal line from various eye positions. The average threshold and latency were 18.0 microA (range 8-30 microA) and 19.5 ms (range 18-20 ms), respectively.
Between 1976 and 1984, 99 patients were treated with radical external irradiation (RT) for squamous cell carcinoma of the head and neck excluding the glottis and paranasal cavity. Twenty-six out of 55 patients (47%) on chemotherapy (CT) were treated by split-course (split) RT, mainly because of acute mucositis. Only 8 out of 44 patients (18%) not on CT were treated by split RT. Although the group given split RT alone rested for 14 days and received 35 Gy, the split RT + CT group rested for 16 days and received a lower dose (30.5 Gy). The mean total doses for each treatment modality were 64 Gy in the continuous course (contin.) of RT alone, 63 Gy in contin. RT + CT, 67 Gy in split RT, and 62 Gy in split RT + CT. The observed/predicted (by a Radiation Therapy Oncology Group) control ratios of primary lesions at 2 yrs were 61/80 (0.76), 72/83 (0.87), 75/73 (1.03), and 69/71 (0.97), respectively. Among patients with a predicted rate of over 80%, the observed rates were almost identical (72%, 74%, 4/4, and 75%, respectively). However, for patients with predicted rates of 50-80%, the observed rate was 71% (12/17) in the group given combined therapy against 50% (5/10) in RT alone group. Among patients with predicted rates under 50%, the observed rate was 57% (4/7) in split RT + CR and only 25% (1/4) in contin. RT; there were no cases in contin. RT + CT. Split RT + CT is considered to be favorable for patients with poor prognostic factors.
Adenylate cyclase activity was studied in Saccharomyces cerevisiae's cell division cycle (cdc) mutant 35-1. The temperature sensitive mutant cdc35-1 was previously mapped as an allele of cyr, the adenylate cyclase gene. However, the adenylate cyclase activities of membranes prepared from cdc35-1 were not thermosensitive. The adenylate cyclase activity of cdc35-1 was found to have an altered Mn2+ dependency and did not respond to Gpp(NH)p stimulation. These results suggest that cdc35-1 mutation may not be at the catalytic site but at a site where adenylate cyclase interacts with regulatory proteins.
Blink reflex responses evoked by electrical stimulation of the supraorbital nerve were examined using cats and the pathway of the blink reflex in the brainstem was elucidated. Both early response (ER) and late response (LR) were mediated by the main sensory trigeminal nucleus and the spinal trigeminal nucleus. However, a lesion of the main sensory trigeminal nucleus had less effect on the blink reflex than a lesion of the spinal trigeminal nucleus. The ER was mediated not only by the shorter disynaptic pathway of 3 neurons through the trigeminal nerve, the trigeminal nuclei and the facial nucleus but also by a polysynaptic pathway of 4 neurons. The interneurons were located between the trigeminal nuclei and the facial nucleus. Some of these interneurons participated in the production of both ER and LR. The area of the brainstem responsible for ER and LR of the blink reflex was the reticular formation from the rostral part of the medulla to the pons except the medial area around the median sulcus. The LR interneurons were distributed more widely than the ER interneurons.
Distant metastases were detected clinically in 25 (14%) of 173 patients with squamous cell carcinoma of the oral cavity and pharynx admitted from 1975 to 1982. The probability of distant metastases was higher in patients with advanced tumor (stages III and IV: 21%; T4: 27%; N3: 37%), lymphoepithelioma (57%) and in patients with a decreased lymphocyte count in the peripheral blood at presentation (less than 1300/microliter; 58%). The incidence of metastases in advanced cases was 45% in the oropharynx, 24% in the nasopharynx and 20% in the oral cavity. Whether the regional tumor had been controlled or not in advanced cases, there was no difference between the incidence and the period of detection of distant metastases.
We previously reported that injection of horseradish peroxidase (HRP) into a physiologically identified region of the thalamus between the ventrolateral nucleus and ventroposterolateral nucleus, VL-VPL, in cat results in labeled cell bodies in the caudal cuneate nucleus (CCN) of the dorsal column nuclei (DCN). We recognized, however, that the spread of HRP to localized regions of less than 1.0 mm distance from the injection site and subsequent uptake by neighboring fibers might have accounted for the resulting label in CCN. In the present study, therefore, we reexamined the DCN input to VL-VPL using a more sensitive physiological method. First, we used the microstimulation technique and corroborated the previous result. In 5 additional preparations, a modified collision procedure was used to ascertain that the same VL-VPL neuron which projects to the motor cortex also receives input from CCN. We report, for the first time, evidence of a lemniscal input to neurons in VL-VPL which are physiologically identified as projecting to the motor cortex.
A kinetic study of Pi transport with 32Pi revealed that Saccharomyces cerevisiae has two systems of Pi transport, one with a low Km value (8.2 microM) for external Pi and the other with a high Km value (770 microM). The low-Km system was derepressed by Pi starvation, and the activity was expressed under the control of a genetic system which regulates the repressible acid and alkaline phosphatases. The function of the PHO2 gene, which is essential for the derepression of repressible acid phosphatase but not for the derepression of repressible alkaline phosphatase, was also indispensable for the derepression of the low-Km system.
A DNA fragment bearing the PHO8 gene, which encodes repressible alkaline phosphatase of Saccharomyces cerevisiae, was cloned. Northern hybridizations with the PHO8 DNA as probe indicated that the PHO8 transcript is 1.8 kilobases in length and is more abundant in cells grown in low-phosphate medium than in high-phosphate medium. The pho9 mutant, whose phenotype is defective in the activity of repressible alkaline phosphatase, produced as much of the PHO8 transcript as did the PHO9+ cells. Hence, the PHO9 product should act at the post-transcriptional level. The pho4 mutant could not derepress the PHO8 transcript, whereas the pho80 mutant could, irrespective of the amount of Pi in the medium, as has been suggested by genetic study.
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Monocular movements of the contralateral eye were demonstrated following the stimulation of the internal kneelike portion of the cortex in the coronal sulcus of the cat. The stimulation of this cortical area in the coronal sulcus yielded rapid medial or slightly oblique ventromedial movement of the contralateral eye. While ablation of the same cortical area produced contralateral eye shift toward the dorsolateral side and the shifted eye became uncontrollable. The results suggested that the control mechanism of eye movement involves unilateral innervation system to the contralateral side as seen in the extremities.
The input to the border region between the ventrolateral nucleus (VL) and ventroposterolateral nucleus (VPL) of the thalamus, VL-VPL, was studied in cats using a combined electrophysiological and anatomical technique. Neurons within this border region receive somatic afferent input and project to a region of the motor cortex having similar receptive fields. In this study we asked the question whether neurons in the VL-VPL border receive input from the dorsal column nuclei (DCN). To answer this question we delivered intra-cortical microstimulation (ICMS) to the motor cortex while a second electrode inserted into the VL-VPL border, filled with a 20% solution of HRP dissolved in KCl, was used to record antidromically activated neurons. When an antidromically activated neuron was encountered and the neuron responded to natural peripheral stimulation, HRP was iontophoretically injected through the recording electrode. After a 48-72 h survival time, cats were sacrificed, and the brain tissue processed according to the method of Hardy and Heimer. Labeled cell bodies were found in the caudal cuneate nucleus (CCN) in all injected animals. These results suggested that neurons in CCN project to cells in VL-VPL which in turn project to the motor cortex.
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The physicochemical and immunochemical properties of a thermo-labile antigen (TLA a) which is located on the cell surface of Saccharomyces cerevisiae were studied. The sedimentation constant (S20,W) and molecular weight (sedimentation equilibrium method) were 6.26S and 68,800, respectively. The circular dichroic (CD) spectrum of TLA a had negative maxima at 210 and 221 nm, indicating the presence of alpha-structure of a polypeptide chain. The molar ratio of antibody to antigen which gave maximum precipitation was 2.7. Approximately 50% of the antigenic activity of heat-denatured TLA a was recovered when denatured molecules were dissolved in 6 M guanidine hydrochloride followed by 25-fold dilution with H2O. The amount of TLA a existing on the yeast cell surface was estimated to be 37.5 micrograms per 10.5 mg of fresh cells, corresponding to 0.36% by weight of the fresh yeast.
Cerebroside, sulfatide, monoglycosyl glyceride, and ester cerebroside were isolated from frog brain and sciatic nerve, and their distribution and chemical constituents were determined. The long-chain base compositions of cerebroside, sulfatide, and ester cerebroside were unique in the presence of branched-base components (5-15% of the total bases) and in the abundance of saturated dihydroxy base components (15-45% of the total). The amount of branched long-chain bases was greater in sciatic nerve than in brain. The hexose composition of the glycolipids consisted entirely of galactose except for brain cerebroside, in which a small amount of glucose was detected. Monogalactosyl glyceride consisted of the diacyl and alkylacyl forms, in a molar ratio of 81:19 for brain and 62:38 for sciatic nerve. The fatty acid composition of glycosphingolipids was characterized by the predominance of hydroxy and nonhydroxy 24:1 acids, and the concentration of 24:0 was extremely low. The proportion of unsaturated fatty acids accounted for 80% of the total. Major fatty acids of monogalactosyl glyceride were palmitic, oleic, stearic, and palmitoleic acids; the highest concentration was that of palmitic acid. Ester cerebroside was separated into three subfractions mainly on the basis of the proportion of hydroxy and nonhydroxy components in the amide-linked fatty acids.
The frontal cortex concerned with eye movements was investigated by electrical stimulation in the cat. Stimulation of the lateral part of the frontal cortex at the coronary sulcus evoked rapid medial movement and enophthalmos of the contralateral eye. The latency of eye movement following cortical stimulation was found to be shorter in the coronary sulcus than in the medial wall of the hemisphere under the cruciate sulcus or in the presylvian sulcus.
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