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Biomedical subjects

T Ichimura

Publications and source records attributed to T Ichimura.

At least 127 records · Page 7Linked to original sources
PubMed1987

Brain 14-3-3 protein is an activator protein that activates tryptophan 5-monooxygenase and tyrosine 3-monooxygenase in the presence of Ca2+,calmodulin-dependent protein kinase II.

We have found that the 14-3-3 protein, an acidic neuronal protein, is substantially identical to the 'activator' protein [(1981) J. Biol. Chem. 256, 5404-5409] that activates tryptophan 5-monooxygenase and tyrosine 3-monooxygenase in the presence of Ca2+, calmodulin dependent protein kinase II. This finding is based on the remarkable similarity of both these proteins in physicochemical, biochemical and immunochemical properties, as well as on detection for the 14-3-3 protein of an activator activity towards tryptophan 5-monooxygenase. The result suggests that the 14-3-3 protein plays a role in the regulation of serotonin and noradrenaline biosynthesis in brain.

14-3-3 Proteins↗
PubMed1986

Identification of the C-terminal portion of a protein by comparative peptide mapping.

A method is presented for the simple identification of C-terminal fragment of proteins. The method consists of (i) C-terminal processing of a protein by carboxypeptidase and (ii) comparative peptide mapping of the intact and carboxypeptidase-excised protein after fragmentation by endoproteinase or by chemical cleavage. The peptide mapping was performed by means of high-performance reversed-phase chromatography, where the C-terminal fragment was identified as a peptide peak that was lost or decreased in the carboxypeptidase-excised protein. The C-terminal sequence of the protein could be then determined by sequential Edman degradation of the C-terminal fragment collected from the peptide mapping chromatography. The sensitivity of the method depends solely on the peptide detection and subsequent Edman degradation, currently available techniques of which require a nanomole to subnanomole quantity of protein. The present method can be coupled with conventional carboxypeptidase technology because it utilizes a protein portion remaining after carboxypeptidase digestion while released amino acids are needed in the conventional technique. The method would be particularly valuable in finding a gene probe site for a RNA message coding for the C-terminal portion of a molecule.

14-3-3 Proteins↗
PubMed1986

Acoustoelectric technique for assessing the mechanical state of the dental implant-bone interface.

A simple technique is described for in vivo assessing the interfacial rigidity between a dental root implant and the bone surrounding it. The method is based on estimating the frequency (10 to 150 KHz) and amplitude of the vibration of the implant induced by a small pulsed force. Application of the force to the implant and detection of the vibrational signal from the implant are performed by lightly touching it with two fine needles connected with piezoelectric elements. A distinct signal difference observed in animal tests of bioactive implant and nonbioactive one is shown to well agree with that obtained from corresponding ex vivo models.

Animals↗
PubMed1986

Fine-structural study of the pineal body of the monkey (Macaca fuscata) with special reference to synaptic formations.

Various types of synaptic formations on pinealocytes and pineal neurons were found in the pineal body of Macaca fuscata. Axo-somatic synapses of the Gray type-II category were detected on the pinealocyte cell body. Gap junctions and ribbon synapses were observed between adjacent pinealocytes. About 70 nerve-cell bodies were detected in one half of the whole pineal body bisected midsagittally. They were localized exclusively deep in the central part. When examined electron-microscopically, they were found to receive ribbon-synapse-like contacts from pinealocytic processes. They also received synaptic contacts of the Gray type-I category on their dendrites, and those of the Gray type-II category on their cell bodies from nerve terminals of unknown origin. All these synapse-forming axon terminals contained small clear vesicles. Thus, the pineal neurons of the monkey, at least in part, are suggested to be derived from the pineal ganglion cells in the lower vertebrates and not from the postganglionic parasympathetic neurons. The functional significance of these observations is discussed in relation to the innervation of the pineal body of the monkey.

Animals↗
PubMed1985

Visualization of the cerebrospinal fluid drainage into the Galen's vein.

Arachnoid granulations are not always present in lower mammals and primate newborns. In order to visualize the route for the cerebrospinal fluid (CSF) to drain into the venous system, horseradish peroxidase (HRP) was injected into the lateral ventricle or cisterna cerebellomedullaris of the mouse and rat. From 30 to 60 min after the commencing of a slow infusion for 15-30 min of 0.05-0.1 ml solution containing 10-20 mg HRP, the mouse, whose skull had been exposed, was dropped into cold acetone at dry ice temperature; other animals were fixed by perfusion with aldehyde solution. The frozen head was dissected in a cryostat kept at -18 degrees C to remove the skull, but leave the dura mater and the falx cerebri. The brain with meninges was cut into 30-45 microns sagittal sections in the cryostat, and processed for peroxidase reaction. The perfusion-fixed brains were used for scanning electron microscopy and for electron microscope observation of the tracer. The reaction product was found within fenestrated venous capillaries of the choroid plexus. The route for the HRP in the CSF to drain into the sinus rectus via the vena choroidea and vena cerebri magna was directly visualized in the mouse.

Animals↗
PubMed1985

Emetic effect of triazolopyrimidine, a pyrimidine compound, in dogs.

The intention of this study was to determine the minimum required dosage of triazolpyridine (TAP) to consistently induce emesis in canines. We administered single oral doses of TAP to 42 adult beagle dogs. The effect of TAP dosage on emesis was highly significant. The effective emetic dosages were 4.0 mg/10 ml water/animal (p less than 0.05) and 8.0 mg/10 ml water/animal (p less than 0.01). In all the dogs tested, 8.0 mg of TAP successfully induced emesis. The mean latency of emesis in the beagle group studied was 15 min, 54 sec (95% confidence limits = 8 min, 11 sec to 23 min, 38 sec). Intravenous apomorphine HCL was used to demonstrate the effectiveness of anti-emetic pretreatment with subcutaneous chlorpromazine (CPZ). Pretreatment with CPZ appeared to inhibit apomorphine-induced emesis, but did not modify the emetic response elicited by TAP. Emesis following the administration of TAP was considered a result of direct action of TAP upon the gastrointestinal mucosa. Eighty adult mongrel dogs were also given TAP doses of 8.0 mg/10 ml water/animal, with 100% effectiveness in inducing emesis.

Animals↗
PubMed1984

Fine structure of basement membranes of the capillary endothelium and perivascular astrocyte in some circumventricular organs by three-dimensional SEM.

The three components of the basement membrane, the lamina lucida, lamina basalis, and lamina reticularis, were examined stereoscopically with a high-resolution scanning electron microscope. Brains of 12 rats and 3 guinea pigs were used. In the lamina reticularis, microfibrils connect to collagen fibrils with one end and anchor to the external surface of the lamina basalis with the other. Their helical substructure, the pitch of helices 70-80 nm and maximum width 15-20 nm on scanning electron micrographs, was reconfirmed. In the lamina lucida, short cross-bridge filaments spanned the basal lamina and the applied plasma membrane. They measured 10-15 nm in diameter, 30-90 nm in length, and were distributed with a regular spacing fo 40-60 nm. It is discussed that the basement membrane serves as the anchorage of the microfibrils and of the cross-bridge filaments and mediates the interconnection between the plasma membrane and extracellular connective tissue elements.

Actin Cytoskeleton↗