Search PubMed⌕ Search

Biomedical subjects

Y Tamai

Publications and source records attributed to Y Tamai.

At least 199 records · Page 11Linked to original sources
PubMed1982

Termination of retinal fibers in lateral preoptic and hypothalamic areas of the crab-eating monkey, Macaca irus.

After a monocular injection of tritiated proline into the vitreous chamber of the eye, the distribution of labeled retinal termination in the hypothalamus of the crab-eating monkey was investigated by autoradiography. The results indicated that a few retinofugal fibers might terminate bilaterally in the lateral hypothalamic areas through the level of the anterior commissure to the infundibulum as well as the suprachiasmatic nuclei. The labeled fibers to the lateral hypothalamic area seemed to leave the dorsocaudal border of the optic chiasma in a dorsolateral direction and then coursed both rostrally and caudally above the supraoptic nucleus: these fibers might progressively diminish in number at more rostral and caudal levels. Further, small clusters of developed silver grains were found bilaterally in the caudal part of the lateral preoptic nuclei.

Animals↗
PubMed1982

Reactivated response of blink reflex in the cat.

Three reflex responses in the orbicularis oculi muscles were observed by electrical stimulation of the trigeminal nerve in lightly anesthetized or conscious cats. The third response, following the first and second responses, was concluded as being a "reactivated response" of the blink reflex as it was set up by the trigeminal afferent input evoked by the palpebral movement of the preceding blink. The reasons for this were as follows: 1) the third response disappeared on administration of muscle relaxants and 2) was enhanced by touching the palpebral hair; 3) the palpebral movement activated the afferent discharges of the trigeminal exteroceptors which were strong enough to yield the reflex responses and 4) the latency of the first reflex response by the palpebral movement corresponded to the time lag between the preceding large reflex response and the third response; 5) the third response was hardly suppressed at all until the first response disappeared over a period of maximum reflex suppression following the conditioned stimulation of the trigeminal nerve.

Action Potentials↗
PubMed1981

Hypolipidemic effect of L-form S-methylmethionine sulfonium chloride in man.

The effect of L-form S-methylmethionine sulfonium chloride (L-MMSC) was studied in 26 patients with hypercholesterolemia during the oral administration period for 8 weeks (daily dose 1500 mg). The oral administration of L-MMSC resulted in the statistically significant decrease of serum total cholesterol (9.7%, P less than 0.001), but not of serum triglycerides. In addition, the statistically significant increases in serum high-density lipoprotein-cholesterol (HDL-cholesterol) and in the ratios of HDL-cholesterol/(total cholesterol) -- (HDL-cholesterol) and HDL-cholesterol/(total cholesterol) + (triglycerides) were observed by the administration of L-MMSC. The therapeutic effects in in-patients were more remarkable than those in outpatients.

Adult↗
PubMed1980

Further studies on the smooth-surfaced membranes isolated from rat brain.

The light and heavy smooth-surfaced membranes (LSM and HSM), which had densities corresponding to 1.08 M and 1.28 M sucrose, respectively, were isolated from rat brain and some of their biochemical properties were investigated. Both LSM and HSM showed high Na+,K+-ATPase activity and, in particular, in HSM the activity was four times (21.55 mumol/mg protein/h) higher than that of the brain homogenate. High 2',3'-cyclic nucleotide 3'-phosphodiesterase activity (293.4 mumol/mg protein/h) was characteristic of LSM. 5'-Nucleotidase and acetylcholinesterase activities were also higher in LSM than in HSM. SDS-polyacrylamide gel electrophoresis showed that LSM and HSM had many protein component and that low molecular weight proteins such as proteolipid protein and basic protein were almost absent, in contrast with myelin and myelin-like membrane. GM1 ganglioside constituted the major class of total ganglioside in both LSM and HSM. These biochemical findings suggested that LSM is a membrane that has not previously been described, or a membrane fraction related to the oligodendroglial plasma membrane.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1979

Neutral lipid and sphingolipid composition of the brain of a patient with membranous lipodystrophy.

Lipids were extracted from brains of a patient with membranous lipodystrophy (ML) and three normal patients and the neutral lipid and sphingolipid constituents were investigated. The storage of a large amount of free fatty acid was observed in the ML brain, but no cholesterol ester was found. Total lipid, cholesterol and cerebroside contents were slightly decreased in the white matter of the ML brain. The composition of free and sphingolipid fatty acids did not differ between ML and normal brains.

Adult↗
PubMed1979

Creutzfeldt-Jakob disease--alteration in ganglioside sphingosine in the brain of a patient.

Gangliosides isolated from the brain of patients with Creutzfelt-Jakob (C-J) disease were analyzed. The ganglioside current was abnormally low, and the percentage distributions of individual gangliosides and the long-chain base compositions were abnormal. The C20-sphingosine contents of all the ganglioside fractions were low. Abnormalities in ganglioside long-chain bases in adult human brain have been reported previously only in patients with inherited metabolic disorders. These abnormalities in C-J disease seem to be closely related to the cause of the disease.

Brain Chemistry↗
PubMed1979

Lipid composition of brain in a patient with mental retardation due to encephalopathy in an infantile period and one due to homocystinuria.

The lipid compositions of brains of a patient with etiologically unknown encephalopathy (ECP) in an early infantile period and a patient with homocystinuria (HCU) were investigated. In the ECP brain the total lipid content and all lipid classes decreased and the degree of the reduction was more conspicuous in the gray matter than in the white matter. The ganglioside distribution was altered in the ECP brain and the ganglioside long-chain base composition was the infantile pattern. It was shown that damage inflicted on an immature brain leaves persistent effects on lipid metabolism in the course of future brain development, resulting mental and neurological dysfunction. The HCU brain retained almost a normal lipid composition. Among disorders of amino acid metabolism it was found that HCU did not significantly affect lipid metabolism in the brain.

Adult↗
PubMed1978

Effect of immunoglobulin G on membrane-bound enzyme activity of sarcoma 180 cells.

Changes in the activity of membrane bound ATPase of Sarcoma 180 cells caused by immunoglobulin G (IgG) of anti-Sarcoma 180 was investigated in relation to the incorporation of amino acid by the cells. Enzymatic activity of ATPase was increased up to 160% of the original activity upon incubation of the cell with IgG. Kinetic studies showed that IgG did not change the affinity of this enzyme for the substrate, but exerted influence upon catalytic efficiency of the enzyme. The rate of incorporation of leucine into Sarcoma 180 cells was also affected by IgG, as observed in the effect of IgG on the enzymatic reaction of the cells.

Animals↗
PubMed1978

Biochemical characterization of the submicrosomal membrane of the rat brain. Selective solubilization of the components of the light smooth-surfaced membrane by lysophosphatidylcholine.

The light smooth-surfaced membrane, one of the three membrane fractions derived from the rat brain microsomal fraction, was fractionated into its soluble and insoluble parts by the use of lysophosphatidylcholine and the chemical composition of these was investigated. Under the condition whereby the maximal amount of the membrane protein was solubilized by lysophosphatidylcholine (0.5% lysophosphatidylcholine at 37 degrees C for 10 min), the insoluble residue, which accounted for approximately 30% of the membrane protein, was ultracentrifugally homogeneous and showed a granular structure under the electron microscope. The lipid composition of the soluble and insoluble fractions, as well as their protein composition, revealed a preferential and limited solubilization of the constituents of the membrane by lysophosphatidylcholine.

Animals↗
PubMed1978

Selenium protection against mercury toxicity: high binding affinity of methylmercury by selenium-containing ligands in comparison with sulfur-containing ligands.

In determining the protection of selenium against mercury toxicity, the binding affinity of methylmercury by various selenium-containing ligands was investigated by proton magnetic resonance (PMR) spectroscopy. The most striking feature was the small J199Hg-1H value of the selenocysteamine- and selenocysteine-methylmercury complexes, namely, the high affinity of the selenohydryl group to the mercury in comparison with those of the sulfhydryl and amino groups. The order of binding affinity of the coordination groups toward methylmercury is clearly SeH greater than SH greater than or equal to Se-Se greater than NH2 greater than S-S, SeCH3, SCH3. A definite correlation was found to exist between the mercury-proton coupling constants and the chemical shifts of methyl groups of the methylmercury complexes. A relationship between the order (Se greater than S greater than NH2) of affinity for methylmercury and the basicity (or electronegativity and covalent radius) of the donor groups was also discussed. These results suggest the high covalency of the CH3Hg-Se bond, which involves dpi-dpi back bonding.

Chemical Phenomena↗