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Biomedical subjects

Jun Sato

Publications and source records attributed to Jun Sato.

At least 37 records · Page 2Linked to original sources
PubMed2005

Augmented mechanical response of muscle thin-fiber sensory receptors recorded from rat muscle-nerve preparations in vitro after eccentric contraction.

Unaccustomed strenuous exercise, especially that from eccentric muscular work, often causes muscle tenderness, which is a kind of mechanical hyperalgesia. We developed an animal model of delayed-onset muscle soreness (DOMS) from eccentric muscular contraction (ECC) in rats and demonstrated the existence of muscle tenderness by means of behavioral pain tests and c-Fos protein expression in the spinal dorsal horn. The purpose of the present study was to examine whether the sensitivities of muscle thin-fiber sensory receptors to mechanical, chemical, and thermal stimuli were altered after repetitive ECC in a rat model of DOMS. ECC was caused in the animals by electrical stimulation of the common peroneal nerve innervating the extensor digitorum longus muscle (EDL) while the muscle was being stretched. Activities of single thin-fiber receptors (sensitive to pressure but insensitive to stretch, with conduction velocity slower than 2.0 m/s) were recorded from muscle (EDL)-nerve preparations in vitro 2 days after ECC when mechanical hyperalgesia was at its peak. The mechanical threshold of thin-fiber receptors was found to be very much lower in the ECC preparations than in the nontreated control (CTR) [median 65.4 mN (interquartile range [IQR]; 46.6-122.0 mN) in the CTR preparation vs. 38.2 mN (IQR; 26.8-55.8 mN) in the ECC, P < 0.001]. In addition, the total number of evoked discharges during a ramp mechanical stimulus, taken as an index of the magnitude of the mechanical response, nearly doubled in the ECC preparations compared with the CTR [24.7 spikes (IQR; 14.2-37.1 spikes) in the CTR preparation vs. 54.2 spikes (IQR; 24.3-89.0 spikes) in the ECC, P < 0.001]. In contrast, the numbers of discharges induced by chemical (pH 5.5, lactic acid, adenosine triphosphate, and bradykinin) and thermal (cold and heat) stimuli were not different between the two preparations. These results suggest that augmentation of the mechanical response in muscle thin-fiber sensory receptors might be related to the muscle tenderness in DOMS after ECC.

Action Potentials↗
PubMed2005

Preliminary study of histological comparison on the growth patterns of long-bone cortex in young calf, pig, and sheep.

Some young large farm animals show a laminar bone formation in the long-bone cortex. Such a laminar bone is gradually replaced by Haversian bone with osteons during their growth periods. In this preliminary study, we observed the transverse ground samples of tibia cortex in young calves, pigs, and sheep by backscattered electron imaging. The cortex bones of all the newborn (NB) animals were basically formed with laminar bone structures. The NB and 1-month-old (1-M) calves had a typical concentric structure of laminar bone, whereas the NB and 1-M pigs showed a wire-netting bone with laminar-bone units. The NB sheep was similar to the calf rather than the pig. In the growth rate of bone volume, sheep was similar to calf up to 6 months after birth (6-M). Such calf and sheep showed a more rapid ratio of bone volume than pig. A few osteons had initially appeared in the innermost layer of the 6-M calf. A 1-year-old (1-Y) calf showed scattered osteons in the bone cortex, but many laminar-bone units were still retained in the outer layer. A 6-M pig had many osteons in the entire cortex but only a few osteons in the outermost layer. In the 6-M sheep, no osteons were observed, whereas a 1-Y sheep showed a relatively small number of osteons mainly in the middle layer but a higher osteon-volume than the 1-Y calf. In the 1-Y sheep, the more widely absorbed areas by bone-remodeling with osteons were observed as compared with the 1-Y calf, and the bone volume was decreased from the 6-M into the 1-Y sheep because of the remarkable bone-absorption. Thus, calf kept on possessing many laminar-bone units for a longer time in the growth period than sheep, while pig showed the earliest bone-remodeling with osteons. These results may be caused by their different body size and withers height in calf and sheep after growing and the difference of the dependence upon mother's body during juvenile period between pig and calf with sheep. The initial region of osteon formation may be distinguishable among their animals, respectively. However, further detailed investigations of their young animals at successive stages will be necessary.

Age Factors↗
PubMed2005

Changes of serum alkaline phosphatase activity in dry and lactational cows.

Serum alkaline phosphatase (ALP) activities were measured during dry and lactational periods to investigate the influence of lactation on serum ALP activity in cows. Higher levels of serum ALP activity were seen in lactational periods than in dry periods. The serum activities of bone-specific ALP (BALP), liver ALP (LALP), tartrate resistant acid phosphatase (TRAP) and aspartate aminotransferase also increased in lactational periods. ALP activities in the bone extract and in whey were decreased at similar rates by the addition of lectin. Moreover, since the ALP band in whey was observed to have the same migration in polyacrylamide gel (PAG) disk electrophoresis as that of the bone extract, analysis of ALP isoenzymes by lectin affinity or PAG disk electrophoresis could not distinguish ALP originating from the mammary gland from that of bone. In this study, it was clear that the increased level of serum ALP activity was due to increases of BALP and LALP in lactational periods. However, the extent of the influence of ALP originating from the mammary glands on serum ALP activity was unknown. Judging from changes of BALP and TRAP activities in the serum and the correlation between the both, it was guessed that ALP originating from the mammary glands influenced serum ALP activity.

Acid Phosphatase↗
PubMed2005

Toxicity studies of tetradecanoic acid, 2-sulfo-, 1-methylester, sodium salt (C14-MES).

We evaluated the toxicity of tetradecanoic acid methyl ester sodium salt (C14-MES), a major component of fabric detergents, following the test guidelines of the Organization for Economic Cooperation and Development. The rat acute oral LD(50) was 1,000 mg/kg in males and 500 mg/kg in females. Applying the combined repeated dose and reproductive/developmental toxicity screening test (ReproTox), we exposed groups of Crj:CD (SD) IGS rats to C14-MES in the diet at concentrations of 0, 0.3, 0.6, or 1.2%. We observed decreases in fibrinogen levels and longer prothrombin time at the 1.2% treated level in females and decreases in serum triglyceride levels in both sexes at the 0.6% and 1.2% treatment levels, but the effects were not clinically significant. The no-observed-effect-level (NOEL) for repeated dose toxicity was 0.3% (175 mg/kg body weight/day for males, 249 for females). The NOEL for reproduction/developmental toxicity was 1.2% (740 mg/kg for males, 1039 for females). C14-MES was negative in the reverse gene mutation assay and the chromosomal aberration test and did not induce skin sensitization in the guinea pig maximization test. These data confirm that C14-MES is of low hazard potential.

Animals↗
PubMed2005

[An adult case of asymptomatic congenital tracheal stenosis].

A 42-year-old woman was admitted with abnormal chest radiographs. Though interstitial pneumonia associated with dermatomyositis was diagnosed, her chest radiograph also revealed a narrowed trachea about 6 mm in diameter. Bronchoscopy showed that her trachea lacked a membranous posterior segment and O-shaped complete tracheal rings were present throughout the trachea, indicating congenital tracheal stenosis. Congenital tracheal stenosis is a rare disorder and is usually recognized in the first few weeks of life, but the patient had no history of dyspnea or recurrent pneumonia. This case suggests that among healthy people there are a very few who have asymptomatic congenital tracheal stenosis.

Adult↗
PubMed2004

Norepinephrine reduces heat responses of cutaneous C-fiber nociceptors in Sprague-Dawley rats in vitro.

Nociceptors are excited or sensitized by many inflammatory mediators as well as by elevation of tissue temperature. We have shown that there is a facilitatory synergistic interaction between norepinephrine (NE) and bradykinin (BK) on cutaneous C-fiber nociceptors in normal Lewis rats. These interactions may play an important role in the mechanism of sympathetically maintained pain. In the present experiment, using skin-saphenous nerve in vitro preparations, we tested the effect of NE on the activity of nociceptive fibers and their response to heat in normal Sprague-Dawley rats. For comparison with the previous data on Lewis rats, we also examined the effect of NE on BK response. NE (10(-5) or 10(-6) M) did not excite nociceptive fibers before repeated heat stimuli or BK superfusion (10(-5) or 10(-6) M) to the receptive field. In contrast, after a few applications of heat or BK, NE excited 20-43% of nociceptive fibers to similar magnitudes. We also found that NE sensitized subsequent BK responses, but somewhat unexpectedly that it suppressed subsequent heat responses. This occurred regardless of the presence or absence of NE-induced excitation. These results suggest different mechanisms of NE modification to the BK and heat responses of cutaneous C-fiber nociceptors.

Animals↗
PubMed2004

To-and-fro optical voltage signal propagation between the insular gustatory and parietal oral somatosensory areas in rat cortex slices.

Taste perception depends not only on special taste information processed in the insular cortex, but also on oral somesthetic processing in the parietal cortex. Many insular cortex neurons show multimodal responsiveness. Such multimodality may be enabled by signal exchange between these two cortices. By using the protocol that we have developed, a synchronized population oscillation of synaptic potentials was induced in the parietal cortex by stimulation to the insular cortex in rat neocortex slices. The spatiotemporal pattern of propagation of this oscillation was studied by recording voltage-sensitive optical signals and field potentials. The first wavelet of the oscillation was propagated from the insular stimulation site to the parietal cortex. However, the second and later wavelets propagated back from the parietal cortex to the insular cortex. The oscillation was detected in the insular cortex as well, but was actually generated in the parietal cortex. Thus, the initial peak of optical signal, sent from the insular to parietal cortex, served to generate oscillatory responses in the parietal cortex, which propagated back to the insular cortex wave-by-wave. We propose that this to-and-fro propagation may be an artificially exaggerated demonstration of an intrinsic mechanism relevant to signal exchange between the parietal and insular cortices.

Animals↗
PubMed2004

Artificially produced meteorological changes aggravate pain in adjuvant-induced arthritic rats.

To examine the effects of change in meteorological parameters on pain-related behaviors in a simulated arthritic condition, rats with an injection of complete Freund's adjuvant into the tibio-tarsal joint were exposed to low barometric pressure (20 mmHg below the natural atmospheric pressure) and low ambient temperature (7 degrees C lower than 22 degrees C) in a climate-controlled room. When the arthritic rats were exposed to these environments, the already increased number of hindpaw withdrawals in response to noxious mechanical stimulation (hyperalgesia) was further increased, and a hindpaw withdrawal response to innocuous mechanical stimulation (allodynia) began to occur. Such exposures did not influence any of the pain-related behaviors of the control rats. These results show that lowering barometric pressure and ambient temperature within the range of natural environmental fluctuation intensify pain in arthritic rats.

Animals↗
PubMed2004

Melanin pigmented oncocytic metaplasia of the nasopharynx.

A case of melanin pigmented oncocytic metaplasia is reported. A 62-year-old man presented with a history of discomfort of the ear of a 2 weeks' duration. Nasoscopic examination revealed a black nodule of about 5mm at the left Eustachian opening, and several black spots were discovered around the bilateral torus tubarius. The nodule was biopsied to determine the histology. Microscopically, there were oncocytic cells with abundant pigmented granules showing glandular pattern. Such a pigmented variant of benign oncocytic lesion is very rare.

Eustachian Tube↗
PubMed2004

Transitional joint effusion in the mandibular prognathic surgery patient: intraoral vertical ramus osteotomy versus sagittal split ramus osteotomy.

PURPOSE: The purpose of this study was to examine the cause of joint effusion (JE) appearing postoperatively in the temporomandibular joint (TMJ) of patients with mandibular prognathism on T2-weighted magnetic resonance (MR) images. PATIENTS AND METHODS: MR imaging was performed before and after surgery in 30 TMJs of 15 subjects with mandibular prognathism who underwent intraoral vertical ramus osteotomy (IVRO) and in 20 TMJs of 10 subjects with mandibular prognathism who underwent sagittal split ramus osteotomy (SSRO). The preoperative MR imaging was performed 1 month before surgery, and postoperative MR imaging was performed during maxillomandibular fixation. RESULTS: Preoperatively, none of SSRO and IVRO groups had JE. Postoperatively, 12 TMJs (40%) of the IVRO group and only 1 TMJ (5%) of the SSRO group had JE. As for the TMJs in the IVRO group, on MR imaging, the degree of downward movement of the condyle after surgery was larger in TMJs with JE (3.8 +/- 2.3 mm) than in TMJs without JE (1.8 +/- 1.6 mm). JE diminished within about 4 months after removal of the maxillomandibular fixation. CONCLUSION: JE appearing postoperatively in the TMJ of patients with mandibular prognathism might be relation to the degree of downward movement of the condyle.

Adolescent↗
PubMed2004

Comparison of cytokine level in synovial fluid between successful and unsuccessful cases in arthrocentesis of the temporomandibular joint.

PURPOSE: The aim of this study was to compare proinflammatory cytokine levels between successful cases and unsuccessful cases of arthrocentesis in patients with internal derangement of the temporomandibular joint (TMJ). PATIENTS AND METHODS: This study involved 73 joints judged as successful and 30 judged as unsuccessful of 103 joints in 100 patients diagnosed with internal derangement of the TMJ and who underwent arthrocentesis. The diluted synovial fluid before undergoing arthrocentesis was aspirated from the superior joint space. The concentrations of interleukin (IL)-1beta, tumor necrosis factor-alpha, IL-6, and IL-8 were measured using an enzyme-linked immunosorbent assay. The differences in the detection rate and concentration of each cytokine between successful cases and unsuccessful cases were analyzed statistically. RESULTS: There was a statistically significant difference between successful cases (72.2%) and unsuccessful cases (95.5%) in the detection ratio of IL-6 (P <.05). There was a statistically significant difference between successful cases (0.017 pg/100 microg protein) and unsuccessful cases (0.046 pg/100 microg protein) in the concentration of IL-1beta (P <.05). CONCLUSION: It has been shown that the presence of IL-1beta and IL-6 in synovial fluid may be indicators of possible unsuccessful treatment following arthrocentesis for internal derangement of the TMJ.

Adolescent↗
PubMed2004

The ideal lavage volume for removing bradykinin, interleukin-6, and protein from the temporomandibular joint by arthrocentesis.

PURPOSE: The aim of this study was to investigate the ideal volume of perfusate for arthrocentesis of the temporomandibular joint (TMJ) disorders (TMDs). PATIENTS AND METHODS: We evaluated 17 joints in 17 patients with TMD in this study. Arthrocentesis of the TMJ was done by perfusion of 400 mL of Ringer's solution. The first 5 mL of perfusate was collected, and then a 5-mL sample was collected when the total volume of perfusate outflow approached 50, 100, 200, 300, and 400 mL. The concentrations of bradykinin, interleukin-6, and protein were measured by immunoassay. RESULTS: The concentration of bradykinin, interleukin-6, and protein during arthrocentesis were effectively reduced by more than 200 mL of lavage (P <.05). With a perfusate volume of 300 to 400 mL, the protein and bradykinin were no longer detectable. CONCLUSIONS: Arthrocentesis is effective for washing out bradykinin, interleukin-6, and protein from the TMJ, and the ideal lavage volume of perfusate for arthrocentesis is between 300 and 400 mL.

Adolescent↗
PubMed2004

Advantages of intraoral verticosagittal ramus osteotomy in skeletofacial deformity patients with temporomandibular joint disorders.

PURPOSE: This preliminary study was performed to clarify the usefulness of intraoral verticosagittal ramus osteotomy (IVSRO) in patients with temporomandibular joint (TMJ) disorders. PATIENTS AND METHODS: We examined 34 sides in 19 consecutive patients with dentofacial deformities with TMJ dysfunction undergoing IVSRO. Preoperatively, 15 patients had TMJ sounds bilaterally and 4 had sounds unilaterally. Five sides in 3 patients had pain in the TMJ, and 4 sides in 3 patients had masticatory muscle pain. The TMJ symptoms, including TMJ sounds, pain in the TMJ, and masticatory muscle pain in each patient, were assessed clinically before and approximately 12 months after IVSRO. Magnetic resonance imaging was also performed to determine joint status, including determination of the positions of the condyle and disc. RESULTS: The symptoms of the TMJ after 12 months of orthodontic treatment showed marked improvements, with the disappearance of the TMJ sounds in 94% of the sides examined. Pain in the TMJ improved in 4 of 5 sides, and pain of the masticatory muscle improved in 3 of 4 sides. With regard to the relative positions of the condyle and disc on magnetic resonance imaging, 6 of 8 joints and 5 of 7 joints showed improvement in anterior disc displacement with and without reduction, respectively. The direction and mean amount of movement in the distal segment were 8 mm in setback, 4 mm in advance, and 5 mm counterclockwise. CONCLUSION: IVSRO is potentially as useful for the treatment of TMJ disorders in orthognathic surgery patients as is intraoral vertical ramus osteotomy, and IVSRO can be used selectively in cases in which intraoral vertical ramus osteotomy is contraindicated.

Adolescent↗
PubMed2004

Interactions of bradykinin and norepinephrine on rat cutaneous nociceptors in both normal and inflamed conditions in vitro.

Many inflammatory chemical mediators excite or sensitize nociceptors, which had led some researchers to believe that they may interact with each other to maintain a persistent painful state. We examined how the excitatory mediators norepinephrine (NE) and bradykinin (BK) interact, using single fiber recordings from cutaneous nociceptors. We observed that NE augmented the BK-induced response in both control and adjuvant-inflamed rats in a way different from NE-induced excitation in inflamed animals only. BK also tended to augment the NE-induced response (examined only in inflamed rats). Our results provide the first evidence that BK and NE synergistically interact on nociceptors.

Animals↗
PubMed2004

Diagnostic significance of carbamazepine and trigger zones in trigeminal neuralgia.

OBJECTIVE: To investigate the relationship between the efficacy of carbamazepine (CBZ) and the presence of the trigger zone for diagnosis of trigeminal neuralgia (TN). Study design CBZ was administered to 61 patients with suspected TN. All patients underwent intracranial examination by magnetic resonance imaging or computed tomography. The final diagnosis was established by oral and maxillofacial surgeon and neurosurgeon. RESULTS: Of the 61 patients, 50 were finally diagnosed as having TN and 6 as having atypical facial pain. CBZ was effective for pain relief in 45 of the 50 TN patients (90%), and in 5 of the 11 patients (45%) with other diseases (P <.005). However, CBZ also relieved pain in some patients other than TN. Thirty of the 31 patients (97%) with a distinct trigger zone and 20 of the 30 (67%) without a trigger zone were diagnosed as having TN (P<0.005). CONCLUSION: The efficacy of CBZ is an auxiliary indicator of TN and the presence of a distinct trigger zone is a strong indicator of TN.

Adolescent↗
PubMed2004

Relationship of calcitonin gene-related peptide in synovial tissues and temporomandibular joint pain in humans.

OBJECTIVE: To elucidate the expression of calcitonin gene-related peptide (CGRP) in synovial tissue taken from the human temporomandibular joint (TMJ) with internal derangement, and discuss the relationship between CGRP and joint pain. STUDY DESIGN: Using an immunohistochemical technique, 48 joints in 48 patients were examined. As controls, synovial tissue specimens from 7 joints with habitual dislocation without pain were also examined. RESULTS: In all of the internal derangement and control subjects, CGRP-positive cells were observed in the connective tissues around the blood vessels beneath the lining cells. The extent score of CGRP was significantly higher in the internal derangement group than in the control group (P=.033). There was a significant positive correlation between the extent score of CGRP and joint pain (P=.036, r=0.30). CONCLUSIONS: These results suggest that the expression of CGRP is increased in the synovial tissues from patients with internal derangement, and that CGRP seems to play an important role in the mechanism of pain production in patients with symptomatic internal derangement.

Adolescent↗
PubMed2004

Interleukin-6 family of cytokines as biochemical markers of osseous changes in the temporomandibular joint disorders.

The aim of this study was to find out whether there was a correlationship between the concentrations of interleukin-6 (IL-6), IL-11, and IL-17 in synovial fluid and osseous changes in the condyle. The synovial fluid was obtained from 61 patients with temporomandibular joint disorders (TMD) and seven healthy volunteers (controls). The concentrations of IL-6, IL-11, and IL-17 were measured by enzyme-linked immunosorbent assay. IL-6 was detected in 43 of 59 (73%), IL-11 in 23 of 52 (44%) and IL-17 in 14 of 51 (27%) samples of synovial fluid. The concentrations of IL-6 and IL-11 in the joints with osseous changes in the condyle were significantly higher than in the joints without osseous changes (P < 0.05) and also higher than in the joints of the control group (P < 0.05). In addition, there was a correlation of concentrations between IL-6 and IL-11 (P < 0.05). These results suggest that IL-6 and IL-11 may participate in the pathogenesis of TMD and induce osseous changes in the condyle.

Adolescent↗