Biomedical subjects

K Hiranuma

Publications and source records attributed to K Hiranuma.

At least 19 recordsLinked to original sources

PubMed1994

Increase of hepatic mRNAS of profilin, actin and extracellular matrix proteins after carbon tetrachloride treatment and partial hepatectomy in rats.

The synthesis of liver collagen increases during the fibrotic process after administration of carbon tetrachloride and during regeneration after partial hepatectomy in rats. In the present study, we investigated the behavior of profilin and actin mRNA under such conditions. Profilin and actin mRNA increased after acute and chronic treatments of carbon tetrachloride, which is associated with the increase of fibronectin, type-III and -IV collagen mRNA. Furthermore, a simultaneous expression of profilin, actin and extracellular matrix proteins was observed during the regeneration of rat liver, that is, all mRNAs of these proteins showed biphasic peaks around 6 h and 48 h after partial hepatectomy. These results suggest that possible coupling might occur between the changes of extracellular matrix and the reorganization of actin cytoskeleton in vivo.

Actins↗

PubMed1994

The healing process of chronic colitis in rats, induced by 2,4,6-trinitrobenzene sulfonic acid, with special reference to the role of fibronectin.

BACKGROUND: The healing process of rat chronic colitis was investigated to evaluate the role of fibronectin produced by fibroblasts in the healing tissue. METHODS: Chronic colitis was produced by intrarectal instillation of 2,4,6-trinitrobenzene sulfonic acid. The healing process was observed by light and electron microscopy and immunocytochemistry. Time course of fibronectin mRNA expression was measured by Northern blot hybridization. RESULTS: By light and electron microscopy, an abundance of young fibroblasts had gathered at the healing tissue and were involved in incorporation into the endothelium of the preexisting vessels, as vasoformative cells, and in transformation to new muscle cells in muscular regeneration. Such processes became pronounced from day 3 and persisted for 6 weeks. Immunocytochemical data showed that fibronectin, produced in the rough endoplasmic reticulum of the fibroblasts and released to the extracellular surface, played inductive roles in the movement and aggregation of such cells and in their contacts with neighboring endothelial cells of the preexisting capillaries. Northern hybridization showed that mRNA coding for fibronectin rapidly reached maximum on day 3 and gradually decreased almost to the control level at 6 weeks. CONCLUSIONS: These observations elucidate the role of young fibroblasts, as multipotent cells, and of fibronectin in acceleration of the healing process in this model of chronic colitis.

Animals↗

PubMed1993

Induction of mitochondrial chaperonin, hsp60, by cadmium in human hepatoma cells.

Mitochondrial dysfunction is readily induced by a low level of cadmium both in vivo and in vitro. The gene expression of mitochondrial hsp60 was induced in a dose- and time-dependent manner and also in parallel with the accumulation of cadmium in mitochondria. The levels of hsp60 mRNA increased with time until 18 h, while the induction of heat shock 70 (hsp70) gene peaked at 6 h and then declined. On the other hand, the levels of metallothionein mRNA reached to a plateau at 6 h and were maintained at this level continuously. These results suggest that the regulatory mechanism and/or the signals for hsp60 induction by cadmium are independent from those of hsp70 and metallothionein.

Biological Transport↗

PubMed1993

An attempt to substitute the cell binding domain of human fibronectin in lambda phage J protein: computer design and expression.

We superimposed hydropathic indexes of the human fibronectin cell binding domain (CBD) on the lambda phage J protein by computer, and substituted 22 amino acids from the fibronectin CBD for a part of the lambda phage J protein. The fibronectin cell binding domain -Arg-Gly-Asp-Ser- (-RGDS-) localizes at the junction of hydrophobicity and hydrophilicity. We selected a similar hydrophobic-to-hydrophilic junction in the J protein region for substitution. This junction corresponds to 150 bp of the PstI fragment of J protein cDNA. We synthesized 150 bp of the relevant PstI fragment that includes the cell binding domain region. The region was then constructed by serial cloning as an expression vector, pJCBD. The vector pJCBD expressed the fused protein named JCBD (M(r) 32 kDa) in E coli XL1-BLUE. The expressed JCBD protein was identified by Western blot analysis in the extract of the pJCBD carrying bacterial lysate using both rabbit anti-lambda phage antiserum and anti-CBD of fibronectin antibody. The JCBD protein appeared to recognize retinoblast cell membrane RGDS-directed receptors, detected by enzyme-linked immuno-sorbent assay and also by binding competition assay with synthetic pentapeptides, Gly-Arg-Gly-Asp-Ser (GRGDS) and Gly-Arg-Gly-Glu-Ser (GRGES). The former competitor inhibited completely fibronectin CBD-dependent binding activity of JCBD, the latter had no inhibitory activity. These results suggest that certain functional proteins engineered by computer design between human fibronectin cell binding domain and lambda phage J protein can be produced.

Amino Acid Sequence↗

PubMed1991

Is there a three neuron arc in the cat utriculo-trochlear pathway?

The utriculo-ocular pathway was examined in decerebrated and anesthetized cats, in which all the vestibular afferents in the labyrinth, except for those innervating the utricular (UT) macula, had been transected. The UT nerve was stimulated with tungsten electrodes which were insulated except for 200 microns at the tips. Stimulation of the UT nerve evoked a small negative (N1) potential in the vestibular nuclei, with a threshold (N1T) less than 25 microA. The stimulus evoked disynaptic EPSPs in ipsilateral abducens (AB) motoneurons. The threshold and latency of the excitatory postsynaptic potentials (EPSPs) was 1.3 x N1T and 1.2 ms, respectively, in accordance with the data of Schwindt et al. (1973). On the other hand, EPSPs with a clear rising phase and short latency, suggesting the existence of a disynaptic pathway, were never observed in any contralateral trochlear (TR) motoneurons, even when triple shocks at intensities of up to 4 x N1T were applied. This stimulus strength was strong enough to activate the UT nerve. Thus it seems very likely that a disynaptic pathway from the UT nerve to contralateral TR motoneurons, is absent or very poorly organized.

Animals↗

PubMed1991

The neuronal organization of horizontal semicircular canalactivated inhibitory vestibulocollic neurons in the cat.

1. The somatic location and axonal projections of inhibitory vestibular nucleus neurons activated by the horizontal semicircular canal nerve (HCN) were studied in anesthetized cats. Cats were anesthetized with ketamine hydrochloride and pentobarbital sodium. 2. Intracellular recordings were obtained from 11 neck extensor motoneurons which were identified by antidromic activation from the dosal rami (DR) in the C1 segment. Stimulation of the ipsilateral (i-) HCN and the ipsilateral abducens (AB) nucleus evoked IPSPs in the motoneurons. These IPSPs were fully or partially occluded when they were evoked simultaneously. 3. Intracellular recordings were obtained from 8 AB motoneurons. Stimulation of the i-HCN and the i-C1DR motoneuron pool evoked IPSPs in the AB motoneurons. These IPSPs were also partially occluded when they were evoked simultaneously, which implied that some HCN-activated neurons inhibit both i-AB motoneurons and ipsilateral neck motoneurons. 4. Unit activity was extracellularly recorded from 30 vestibular neurons that were activated monosynaptically by i-HCN stimulation. Their axonal projections were determined by stimulating the i-AB nucleus and the i-C1DR motoneuron pool. Eight neurons were activated by both stimuli, and were termed vestibulooculo-collic (VOC) neurons. Their axonal branching was examined by means of local stimulation in and around the i-AB nucleus and the i-C1DR motoneuron pool. Eighteen neurons were antidromically activated from the i-C1DR motoneuron pool but not from the i-AB nucleus. These were termed vestibulo-collic (VC) neurons. Four neurons were activated from the i-AB nucleus but not from the ventral funiculus in the C1 segment, and were termed vestibulo-ocular (VO) neurons.(ABSTRACT TRUNCATED AT 250 WORDS)

Abducens Nerve↗

PubMed1990

Localization and synaptic effects of inhibitory vestibulocollic neurons activated by the posterior semicircular canal nerve in the cat.

Cellular locations, axonal projections, and synaptic effects of inhibitory vestibulocollic (VC) neurons activated by the ampullary nerve of the posterior semicircular canal (PCN) were studied in anesthetized cats. The inhibitory VC neurons were identified by their monosynaptic responses to PCN stimulation and by their antidromic responses to stimulation of the ipsilateral (i-) and contralateral (c-) neck extensor motoneuron pools, which are inhibitory targets of the PCN. They were classified as VCi (vestibulocollic neuron sending an axon to the i-neck extensor motoneuron pool) and VCc (vestibulocollic neuron sending an axon to the c-neck extensor motoneuron pool) neurons. Neither VCi nor VCc neurons were activated antidromically by localized stimulation of the ascending medial longitudinal fasciculus (asc. MLF) or the 3rd nuclei. Their cell somata were localized in the rostral part of the descending vestibular nucleus and the ventral part of the lateral vestibular nucleus. VCi and VCc neurons produced unitary IPSPs in neck extensor motoneurons in the C1 segment.

Action Potentials↗

PubMed1990

Axonal trajectories of inhibitory vestibulocollic neurons activated by the anterior semicircular canal nerve and their synaptic effects on neck motoneurons in the cat.

Somatic location, axonal trajectories and synaptic effects of inhibitory vestibulocollic neurons which were activated by selective stimulation of the anterior semicircular canal nerve (ACN) were studied in the anesthetized cat. ACN stimulation evoked disynaptic inhibitory postsynaptic potentials (IPSPs) in neck flexor motoneurons. This was seen in all the (64/64) tested motoneurons innervating the ipsilateral (i-) longus capitis (LC) and the i-sternocleidomastoideus (SCM) muscles and in 86% (38/44) of the motoneurons innervating the contralateral (c-) LC muscle. The inhibitory relay neurons, identified by orthodromic and antidromic responses to stimulation of the ACN and the i- and c-LC motoneuron pools, were classified as VCi (vestibulocollic neurons sending an axon to the i-LC motoneuron pool) and VCc (vestibulocollic neurons sending an axon to the c-LC motoneuron pool) neurons. Neither VCi nor VCc neurons were activated antidromically by localized stimulation of the ascending medial longitudinal fasciculus (asc. MLF) or the 3rd nuclei. They were located in the medial, descending and ventral lateral vestibular nuclei. It was also observed that VCi neurons produced unitary IPSPs in i-LC and i-SCM motoneurons in the C1 segment. Inhibitory synapses were estimated to be on the cell somata and/or the proximal dendrites of the motoneurons.

Animals↗

PubMed1990

[Properties of experimental high abrasion resistance plastic teeth].

High abrasion resistance plastic teeth made of microfilled urethane dimethacrylate resin were developed around ten years ago. In recent years, several of this same type of resin teeth were developed and introduced commercially in Japan. Many studies have reported the properties of restorative resin materials, but few comparative studies have been conducted among the various resin teeth on the market. The purpose of this study was to compare the basic physical properties of conventional acrylic resin teeth as dental materials with an experimental high abrasion resistance plastic for posterior teeth made of microfilled urethane dimethacrylate. In addition, we compared the properties of the experimental teeth with the other high abrasion resistance plastic teeth including a comparative study of anterior and posterior teeth already on the market. The results indicated that basic physical properties of the experimental posterior resin teeth were better than those of the conventional acrylic resin teeth, but the staining resistance of the former was a little lower than that of the latter. Further, the experimental posterior teeth appeared to have physical properties equal to those of other resin teeth of the same type, but the staining resistance of the experimental resin teeth was higher.

Acrylic Resins↗

PubMed1989

[Study of a particle counting method for index of masticatory efficiency].

The present report discusses our new simplified measuring method of masticatory efficiency by counting particles in the matter of making test materials and the standard equation for subjects with normal dentition. 1. Two kinds of hydrocolloid impression materials, reversible and irreversible, were used as the test materials. 2. For evaluating the shape of test materials, 12 subjects with normal dentition were tested and for calculating the standard equation, 108 subjects with normal dentition were tested. 3. Each subject was investigated by the simplified method of counting particles through a sieve system. The number of remaining particles on the mesh was calculated as a masticatory performance. 4. As indicated in a previous report by Dr. Ozawa about cubical test materials, columnar test materials are easier to make than the others and these were avairable for the present particle counting method for investigating masticatory efficiency. 5. We obtained the standard equation for both kinds of test material using 108 subjects with normal dentition. To simplify the measuring method, we selected the standard equation of a 5-mesh sieve with 10 strokes chewing for the index of masticatory efficiency. The standard equation of a 5-mesh sieve for both test materials are as follows; 1) Reversible hydrocolloid test material: Y = -1.605X+29.058 2) Irreversible hydrocolloid test material: Y = -1.116X+23.868 6. 5, 10-mesh sieve with 10 strokes chewing showed the smallest variation in the individual coefficient of variation with both kinds of test material.

Colloids↗

PubMed1989

[Evaluation of masticatory efficiency and the analysis of occlusal pattern factors using computer image processing method].

The purpose of this study was to evaluate the newly developed computer-assisted image processing method. We applied this method for the evaluation of masticatory efficiency and the analysis of occlusal pattern factors: the number and the size of occlusal contact areas, the number of and the size of the projected facets. We compared this new method with our conventional one which is the simplified particle counting method using a sieve and measuring the occlusal pattern factors with a planimeter. The results were as follows: 1. It is possible to count the number of particles within an optional range of size with the new method. 2. The new method may be used with minimum error for the measurement of occlusal pattern factors. We believe that this newly developed computer-assisted image processing method can be put to practical use for clinical evaluation of masticatory efficiency and analysis of occlusal pattern factors.

Dental Occlusion↗

PubMed1989

[Survey on oral and maxillofacial injuries in contact sports and diffusion of mouthguards].

Recent reports have shown an increase of oral and maxillofacial injuries caused by sports activities. In European and American countries, mouthguards are the popular measure against these injuries. The purpose of this study was to survey the rate of incidence of oral and maxillofacial injuries caused by contact sports, the diffusion and the evaluation of mouthguards and the interest in mouthguards in Japan. Questionnaires were sent to 244 Rugby football teams in Aichi prefecture and 27 American football teams in the Tokai area. We received replies from 153 Rugby football teams and 17 American football teams, and the results were as follows: 1) The rate of incidence of oral and maxillofacial injuries was 239 players out of 4721 players, which means 5.1% in Rugby football and 22 players out of 428 players, which means 5.1% in American football. 2) The diffusion of mouthguards was 20 out of 153 teams in Rugby football and 16 out of 17 teams in American football. And most of them are using commercially available mouthguards. 3) Almost all teams were not satisfied with their mouthguards and complained of speaking difficulties, discomfort and easy dislocation. 4) Almost all teams desire the improvement of mouthguards. 5) Teams with no experience of mouthguards were very much interested in the use of mouthguards but they do not have enough information about mouthguards. 6) We have to enlighten players and their instructors about mouthguards and diffuse the use of mouthguards more positively to contact sports players.

Adolescent↗

PubMed1984