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Biomedical subjects

Y Munakata

Publications and source records attributed to Y Munakata.

At least 19 recordsLinked to original sources
PubMed1992

Isolation and characterization of a gene encoding rat nucleoside diphosphate kinase.

Two overlapping genomic clones for a rat nucleoside diphosphate kinase (NDP kinase) have been isolated and characterized. Complete sequencing of the genomic segment including the whole coding region for the enzyme revealed that the gene consists of four exons spanning 5.5 kilobase pairs. Primer extension analyses and ribonuclease protection assays indicated that the transcription may start from multiple sites with the major initiation site at 3 base pairs upstream from the translation initiation site, Met-1. Neither CAAT-box nor TATA-box could be assigned for each transcription initiation site, whereas five putative Sp1-binding sites (GC-boxes) were present in the 5'-flanking region. These features of the NDP kinase gene represent those of housekeeping genes. In genomic Southern blotting using a full-length rat NDP kinase cDNA as a probe, many positively hybridized fragments were detected. In support of this, five possible processed pseudogenes were identified in different DNA segments although many other NDP kinase-related genomic fragments remained to be characterized. These results demonstrate that the NDP kinase gene may consist of a multiple gene family.

Amino Acid Sequence↗
PubMed1992

The origin of short- and long-latency mylohyoid nerve responses elicited by high-intensity electrical stimulation of intradental nerve in cats.

A double reflex response of the mylohyoid nerve to the jaw depressor muscles after electrical stimulation of the intradental nerves was recorded in cats anaesthetized with alpha-chloralose. The threshold value of the long-latency (16-19 ms) response was almost 20 times greater than that of the short-latency (5-8 ms) response. At the threshold intensity of the long-latency response, the short-latency response with shorter latency appeared. After extirpation of the stimulated tooth pulp, the short-latency response with a lower threshold disappeared, whereas the short-latency response with a higher threshold and the long-latency response both persisted and showed no change in threshold or latency. These findings indicate that the low-threshold, short-latency response was due to excitation of pulpal nerve fibres, while the high-threshold, short-latency response and the long-latency response were both due to excitation of extrapulpal afferent fibres as a result of the spread of current outside the tooth.

Animals↗
PubMed1992

Clonal frequency analysis of B cells producing pathogenic anti-DNA antibody-associated idiotypes in systemic lupus erythematosus.

In order to identify the mechanism responsible for autoantibody production in systemic lupus erythematosus (SLE), B cell repertoires associated with anti-DNA idiotypes were explored by a limiting dilution analysis using Epstein-Barr virus (EBV) transformation methods and ELISA spot assays. The frequencies of B cell clones producing antibodies to DNA and to conventional antigens, tetanus toxoid, dinitrophenyl, or keyhole limpet hemocyanin were higher in active SLE compared to those in inactive SLE and in normal subjects. In addition, there was a disproportionate increase in anti-DNA antibody- and anti-DNA idiotype (Id)-producing clones at the precursor cell levels as well as at the mature cell level. On the other hand, numbers of anti-Id clones against anti-DNA-Id, termed 0-81 Id, were markedly increased at inactive stages of the disease but not at active stages. These were confirmed by serial studies in some patients with SLE. These results support a two-step mechanism for autoantibody production, in which initial polyclonal activation is followed by an antigen-driven process, and indicate an alteration of the precursor B cell repertoire in SLE, which may also associate with a preferential expansion of anti-DNA clones.

Antibodies, Antinuclear↗
PubMed1992

Contribution of the mucosal tactile information to the mandibular position sense in patients wearing dentures.

The effects of mechanical stimulation of denture-bearing mucosa on the perception of mandibular position was tested in five patients wearing dentures. In order to produce mucosal stimulation of different intensities, five types of a punctate stimulus plate each having a different number of raised points was used. A hydraulic vertical displacement meter was also used so as to vary mandibular position. The mandibular position sense altered with changes in the physical stimulus intensity to the denture-bearing mucosa within a limit of jaw separation (less than 2.3 mm). In addition, the increases of the stimulus intensities stabilized the response regarding the mandibular position discrimination. From these results, it has been suggested that the tactile information from the denture-bearing mucosa regulates the neural mechanism concerning the mandibular position discrimination.

Aged↗
PubMed1991

Occlusal force pattern during rhythmic human tapping movement.

The dynamic occlusal force patterns associated with the performance of rhythmic tapping movement were analysed in normal subjects, who were instructed to make tapping movements at four frequencies, 2, 2.5, 3.3 and 5 Hz, with as constant a magnitude of force as possible. The occlusal force recorded by an intra-oral customized device showed a triphasic pattern which could be divided into two components, and this pattern was more clearly defined during slower tapping movements. Of the two components, the first was relatively stable, regardless of changes in tapping frequency, while the second was highly dependent on the tapping cycle duration, and its duration was shortened with increases in tapping frequency. Furthermore, there was a significant correlation between the changes in the occlusal power phase and those in the burst duration of the masseter EMG simultaneously recorded by a pair of surface electrodes. On the basis of these findings, it is suggested that the tapping rhythm is modulated by the duration of the occlusal power phase and the associated jaw elevator muscle activity.

Adult↗
PubMed1990

Determination of occlusal vertical dimension by means of controlled pressure against tissues supporting a complete denture.

In order to establish the vertical dimension (VD) of a complete denture prosthesis, a new method of determining a comfortable mandibular position was tested using a recently designed hydraulic jack (hydraulic vertical displacement meter) in five edentulous patients. The device was designed so as to vary occlusal height by means of an extraoral jig connected to intra-oral hydraulic jacks, and to distribute the bite pressure applied against the denture-supporting tissue in approximately the same pattern as that produced by a denture with a VD preferred by the patient. The most comfortable mandibular position determined by this method coincided remarkably with the preferred VD of each patient in our study, indicating that the new device may be used to establish VD for complete denture construction.

Aged↗
PubMed1990

Effects of chelated sera and alteration in calcium concentration on the growth of oral epithelial cells in primary culture.

The purpose of this study were to examine the distribution of growth-promoting activity of some chelated sera and to investigate the relationship between calcium concentration in culture medium and the growth-promoting activity of the chelated sera in comparison with that of the original serum. Results showed that the chelated serum obtained by acidic resin treatment promoted colony formation, while the number of colonies decreased in cultures containing either dialyzed serum or chelated one obtained by treatment with alkaline resin. The acid-chelated serum and its lyophilized materials maintained the growth-promoting activity for 6 months or more in a deep freezer. This activity depended on the calcium concentration of culture medium in the range from 0.06 to approximately 1.5 mM. The optimal concentration of this material for growth promotion was 4 mg/ml as the protein density, which was about a quarter of that for the original serum protein. Sera from different sources treated with the acidic resin also showed similar effect on the growth. This finding strongly suggests that the acid-chelated serum and its lyophilized protein contain a keratinocyte growth factor(s).

Animals↗
PubMed1989

Comparison of jaw-opening reflex response elicited by anterior and posterior tooth tapping in the cat.

The response elicited by various levels of controlled mechanical stimuli to maxillary teeth was studied in 8 adult cats anaesthetized with alpha-chloralose. When an anterior tooth was tapped, short (4-6 ms) and long (16-20 ms) latency responses were recorded from the mylohyoid nerve. On the other hand, when a posterior tooth was tap-stimulated, only the long-latency response was induced. The effects of ether narcosis on the responses were studied. As the short-latency response was induced only by anterior tooth tapping and its amplitude increased according to increases in stimulus intensity, the response may be related to the protection of the mouth from entrance of harmful materials. The long-latency response was induced by light tapping on both anterior and posterior teeth and its amplitude increased according to increases in stimulus intensity to the posterior teeth rather than the anterior teeth. As it was readily inhibited by ether, the long-latency response may have a reflex centre in an area like the brain stem reticular formation which is particularly sensitive to ether and may be related to the regulation of jaw movement in mastication.

Action Potentials↗
PubMed1989

[Jaw and perioral reflexes elicited by tooth tapping in the cat].

The reflex responses elicited by tapping the maxillary canine were studied in 12 adult cats anesthetized with alpha-chloralose. Short (4-8 msec) and long (14-22 msec) latency responses were recorded from both efferent nerves innervating a digastric muscle and an inferior portion of perioral muscles. These two responses were also observed from a single fiber teased from the efferent nerve as two successive groups of spike discharges. The long-latency responses from the digastric and the perioral muscle were both elicited by a light tooth tapping and disappeared at about the same time following infiltration of local anesthetic over the tap-stimulated tooth root or following inhalation of ether narcosis. The long-latency responses from the above muscles may be, therefore, elicited by the same sensory information of the periodontal afferent, and have a common reflex center.

Animals↗
PubMed1988

Alcohol-induced enhancement of intestinal gamma-glutamyl transpeptidase activity in rats and humans: a possible role in increased serum gamma-glutamyl transpeptidase activity in alcoholics.

It is a well-known phenomenon that serum gamma-glutamyltranspeptidase (gamma-GTP, EC 2.3.2.2.) activity is increased after chronic consumption of ethanol, and gamma-GTP has been, therefore, widely used as a sensitive marker for detection of alcoholism and its related liver disease. However, the precise mechanisms whereby the chronic ethanol consumption leads to an increase in serum gamma-GTP activity are not fully understood. In the present study, we investigated the relationship between the intestinal and serum gamma-GTP activities after chronic ethanol consumption both in rats and humans. Chronic ethanol feeding to rats resulted in a significant increase in serum gamma-GTP activity associated with a significant increment of the intestinal gamma-GTP activity. The histochemical staining of gamma-GTP in the mucosa of the small intestine of these animals demonstrated enhanced gamma-GTP activity at the microvilli of the brush border membrane, lamina propria of the mucosa, and endoplasmic reticulum of the intestinal epithelial cell. The augmented activity in the lamina propria was mainly localized at the submucosal lymphatics. Histology of the small intestine of human alcoholics was, more or less, similar to those observed in alcoholic rats. We further investigated the gamma-GTP activity in the mesenteric lymph using the animal model of lymphorrhea, and found that the gamma-GTP activity was increased by 83% when expressed per unit of lymph in the ethanol-fed rat, accompanied by a marked decrease of serum gamma-GTP activity, suggesting a close relationship between the serum and the intestinal gamma-GTP via the lymphatic channel.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcoholism↗
PubMed1987

[The possibility of surgery for aged patients with gastric cancer].

The possibility of surgery for aged patients with gastric cancer has been studied. Of 484 cases who underwent a gastrectomy, patients 70 years of age or over amounted to 86 (20%). The postoperative mortality rate for these aged patients was 3% and the postoperative mortality rate with hospital deaths added from other causes than operative deaths was 7%. The postoperative mortality rate of aged patients who underwent total or proximal subtotal gastrectomy improved during the period between 1975-1983 compared with the period between 1967-1974. In the second period, there were no deaths among aged patients who underwent an R3-operation and/or a combine operation. This fact shows that operative procedures have become safer for aged patients.

Adult↗
PubMed1986

The effects of changes in bite pressure and mucosal stimulation on the perception of mandibular position in man.

In edentulous subjects, the mandibular position (MP) was altered by adjustable hydraulic jacks attached to the denture base. The MP which they began to perceive as high (HMP) was shifted toward the closed position when the bite pressure against the incisal region was increased. Thus the perception of MP may be modulated by information concerning the distribution of bite pressure. The HMP also shifted toward the closed position when the incisal palatal region of the denture-supporting mucosa was subjected to increased mechanical stimulation, the distribution of the bite force being constant. Therefore, mechanoreceptors in the mucosa may be involved in the perception of MP by providing precise information as to the distribution of bite pressure.

Aged↗
PubMed1985

Syringadenocarcinoma papilliferum.

A giant tumor developed on the right chest wall of a 52-year-old housewife over a 20-year period. It was accompanied by a spider-like invasion of skin, and a lymph node was palpated in the right axilla. Wide excision of the lesion was carried out. The cross-section of the tumor showed two different appearances. The tumor was histologically diagnosed as a syringadenocarcinoma papilliferum. The post-operative course was uncomplicated and without evidence of recurrence.

Adenocarcinoma, Papillary↗