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Biomedical subjects

Y Tsukiyama

Publications and source records attributed to Y Tsukiyama.

16 recordsLinked to original sources
PubMed2003

A simplified sieve method for determining masticatory performance using hydrocolloid material.

The purpose of this study was to develop a simplified technique for measuring masticatory performance by measuring the particle size distribution of masticated hydrocolloid impression material using a sieve method. Masticatory performance was defined as the rate of increase in the number of particles of masticated material on specific sieves with the increment in the number of chewing strokes. The number and weight of masticated hydrocolloid impression material on 10 sieves were compared with results for peanuts. The reproducibility of this method to determine masticatory performance was then examined. In seven sieves, there was a linear relationship between the number of particles and the number of chewing strokes for the hydrocolloid impression material; Pearson's correlation coefficient was higher for the hydrocolloid impression material than for peanuts. Measuring masticatory performance three times a day and three times every week revealed there were no differences in intra-individual variation in masticatory performance in six sieves. There was no significant difference between the masticatory performance calculated from two mastication tasks using the specific sieves and that calculated from seven tasks. These results suggest that this simplified sieve method using hydrocolloid materials can be reliably used for research purposes and in clinical situations.

Adult↗
PubMed2003

NF-kappaB activation and iNOS expression in the synovial membrane of rat temporomandibular joints after induced synovitis.

NF-kappaB plays a pivotal role in pathogenesis in general arthritis. However, the participation of NF-kappaB in inflammation of the temporomandibular joint (TMJ) is poorly understood. We examined NF-kappaB expression in rat TMJs with synovitis induced by condyle hypermobility. By immunohistochemistry, NF-kappaB immunoreactivity was found mainly in the cytoplasm, not the nucleus, of the synovial lining cells of induced-synovitis and control TMJs. Southwestern histochemistry, a new method for detecting transcription factors, showed greater NF-kappaB expression in the nucleus of the synovial lining cells in the hypertrophic synovium than in control synovium. Increased numbers of the synovial lining cells with immunoreactivity for inducible nitric oxide synthase (iNOS), which is transcriptionally regulated by NF-kappaB, were also seen in the inflamed synovium. These findings indicate that excess mechanical stress increases NF-kappaB activation in the TMJ and suggest that active NF-kappaB is involved in the progression of TMJ inflammation.

Animals↗
PubMed2001

Evaluation of oral health promotion in the workplace: the effects on dental care costs and frequency of dental visits.

UNLABELLED: An oral health promotion program has been conducted since 1989 at a shipyard in Japan. AIMS: The purpose of the present study was to assess the impact of oral health promotion in the workplace in terms of dental care costs and frequency of dental visits. METHODS: This program consisted of orientation, an initial regimen, and group counseling. The initial regimen included an evaluation of each participant's oral health status, and instruction concerning oral hygiene, and prevention of oral disease. The participants were selected with each unit being a preexisting peer group. Eighty-seven participants were compared with 216 control subjects in terms of annual dental care costs and frequency of dental visits in four periods: the 1-year period before the program, the 1st year after the program, the 2nd year after, and the 3rd year after. RESULTS: The annual mean dental care cost in the participant group for the year prior to the program was higher than that in the control group (21,317 vs. 17,116 yen). In the 1st year after the program, the difference increased (26,642 vs. 19,481 yen). In the 2nd and 3rd years after the program, dental care costs in the participant group were lower than those in the control group (2nd year: 18,305 vs. 22,841 yen, 3rd year: 16,911 vs. 21,920 yen). CONCLUSIONS: It can be concluded that this oral health promotion program in the workplace contributed to saving of costs associated with dental care. The workplace can be regarded as a key area for implementation of an oral health care system to make good use of limited resources.

Dental Care↗
PubMed2001

An evidence-based assessment of occlusal adjustment as a treatment for temporomandibular disorders.

STATEMENT OF PROBLEM: Occlusal adjustment therapy has been advocated as a treatment modality for temporomandibular disorders. In contrast to this position, a panel at the 1996 National Institute of Health technology assessment conference on TMD indicated that no clinical trials demonstrate that occlusal adjustment is superior to noninvasive therapies. PURPOSE: This article summarizes the published experimental studies on occlusal adjustments and temporomandibular disorders. MATERIAL AND METHODS: Eleven research experiments involving 413 subjects with either bruxism (n = 59), temporomandibular disorders (n = 219), headaches and temporomandibular disorders (n = 91), or chronic cervical pain (n = 40) were selected for critical review from the English dental literature. RESULTS: Three experiments evaluated the relationship between occlusal adjustment and bruxism. Six experiments evaluated occlusal adjustment therapy as a treatment for patients with primary temporomandibular disorders. One experiment looked at occlusal adjustment effect on headache/temporomandibular disorder symptoms; another looked at its effect on chronic neck pain. Most of these experiments used a mock adjustment or a comparison treatment as the control condition in adults who had an existing nonacute general temporomandibular disorder. Overall, the data from these experiments did not demonstrate elevated therapeutic efficacy for occlusal adjustment over the control or the contrasting therapy. CONCLUSION: The experimental evidence reviewed was neither convincing nor powerful enough to support the performance of occlusal therapy as a general method for treating a nonacute temporomandibular disorder, bruxism, or headache.

Adult↗
PubMed2001

A review of temporomandibular disorder diagnostic techniques.

The American Dental Association has approved several devices as aids in the diagnosis of temporomandibular disorders. Concerns remain, however, about their safety and effectiveness. This article reviews the validity and use of several instruments that claim to serve as aids in the detection of masticatory muscle pain, trismus, joint noises, and limitation of jaw motion. A review of data from 62 published articles indicated that, although commercial devices that measure jaw muscle tenderness, muscle activity levels, joint noises, and jaw motion are safe and can document these phenomena, cost-benefit analyses of these devices have not yet been conducted. Moreover, these devices have not been shown to have stand-alone diagnostic value and, when tested, they have demonstrated unacceptable sensitivity and specificity levels. None of the instruments reviewed in this article can be said to provide more than ancillary documentation.

Auscultation↗
PubMed2000

Reliability, validity, and utility of various occlusal measurement methods and techniques.

STATEMENT OF PROBLEM: The controversy continues regarding the efficacy of several commercially available devices that are used as aids in the diagnosis of occlusal abnormalities. PURPOSE: This article reviews the reliability, validity, and utility of instruments that claim to detect occlusal interferences and abnormal vertical dimension of occlusion. MATERIAL AND METHODS: Data, opinions, and technical information from 37 published articles were reviewed. Evidence for method reliability, validity, and utility was assessed. RESULTS: Although occlusal contact detection devices can document the occlusal contact patterns on teeth, the basic in vivo testing of their reproducibility and validity has not been performed. Moreover, while EMG and jaw tracking systems can indeed measure jaw muscle activation and jaw position, no cost-benefit analysis of these devices has yet been conducted. One manufacturer suggests that these instruments be used in conjunction with an electrical muscle stimulation device to find a new resting jaw position that is more open vertically. This new, more open position has been inappropriately labeled as evidence of vertical dimension of occlusion over-closure. CONCLUSION: None of the instruments reviewed can be said to be more than ancillary documentation devices and they have been inadequately tested for reliability and validity. Moreover, because scientifically acceptable disease definitions are not available for these 2 conditions, the issue of over-diagnosing becomes a substantial concern.

Dental Occlusion↗
PubMed1999

Haemodynamic changes in human masseter and temporalis muscles induced by different levels of isometric contraction.

This study evaluated the influence of low contraction forces on intramuscular haemodynamics in human masseter and temporalis using near-infrared tissue spectroscopy. This method allowed the intramuscular haemoglobin (Hb) to be assessed dynamically before, during and after a 5, 15, 25 and 100% maximum voluntary contraction (MVC). Twenty volunteers, 10 males and 10 females, without pain or dysfunction in the masticatory system were included in this study. Data were recorded for 30 s before, 30 s during and 5 min after the four sustained contraction tasks. The results showed that all four levels of voluntary contraction produced a clear haemodynamic response (during and after contraction) in both muscles. For analytical purposes, the maximum Hb achieved after 100% MVC was set equal to 1.00. In the masseter the mean peak Hb during the 5, 15, 25 and 100% MVC was 0.49, 0.92, 1.30 and 1.73 while after the contractions it was 0.50, 0.65, 0.78 and 1.00, respectively. In the temporalis the peak Hb during the contractions was 0.23, 0.36, 0.48 and 0.66 and after the contractions 0.32, 0.45, 0.56 and 1.00, respectively. Repeated-measures analysis of variance revealed a significant main effect for the different contraction levels both in the masseter (during contraction, p = 0.001; after contraction, p<0.001) and the temporalis (during contraction, p = 0.002; after contraction, p<0.001). These data suggest that low levels of contraction induce a clear haemodynamic response, even at 5% effort. When compared, the masseter and anterior temporalis showed clearly different patterns for the Hb signal during the contraction (p<0.001) as well as after it (p = 0.007). Specifically, the Hb during the contractions in the masseter appeared more stable than in the temporalis, which showed a strong return to baseline. Obviously the contracting masseter had a stronger and more sustained venous occlusion than the contracting temporalis. It is speculated that variation in architecture between the two muscles contributes to these differences in blood flow.

Adult↗
PubMed1999

Sixty-eight years of experimental occlusal interference studies: what have we learned?

STATEMENT OF PROBLEM: Understanding is needed regarding the effect that occlusal interferences have on the teeth, periodontium, and especially on jaw function. PURPOSE: This article summarizes research in which experimental occlusal interferences have been placed on the teeth of animals and human volunteers. MATERIAL AND METHODS: Data from 18 human and 10 animals studies were reviewed. Experimental occlusal interferences were grouped into those that alter intercuspal position and those contacting on lateral jaw movement only. The outcome of these interferences were analyzed according to their local pulpal-periodontal, jaw function, or bruxism effects. RESULTS: Experimental occlusal interferences in maximum intercuspation had a deleterious effect on periodontal and pulpal tissues of the affected tooth; sometimes this produces a disruption of smooth jaw function and occasionally jaw muscle pain and clicking. Experimental occlusal interferences that contact only in a lateral jaw movement are infrequently harmful to jaw function. Furthermore, no reliable evidence demonstrates that occlusal interferences can cause nocturnal bruxism, or stop it. CONCLUSION: Transient local tooth pain, loosening of the tooth, a slight change in postural muscle tension levels, chewing stroke patterns, and sometimes a clicking joint can be induced by an experimental occlusal interference. Because such findings are present in relatively asymptomatic patients, these data do not prove that occlusal interferences are causally related to a chronic jaw muscle pain or temporomandibular joint dysfunction problems.

Animals↗
PubMed1999

Cold pressor stimulation effect on hemodynamic changes following sustained isometric contraction in human jaw-closure muscles.

It is postulated that an altered adrenergic response pattern may be associated with chronic muscle pain states. To evaluate this hypothesis, one must fully understand the effect of an adrenergic activation on masticatory muscle blood flow under various conditions. This study evaluated the effect of a 12 degrees C cold pressor stimulation (a mild adrenergic activator), applied to the hand-forearm area, on intramuscular hemodynamics in the human masseter and temporalis muscles following a sustained isometric contraction. We assessed hemodynamics by measuring intramuscular hemoglobin concentration repeatedly, using a non-invasive near-infrared spectroscopy device. Measurements were taken before, during, and after a 30-second sustained 50% maximum voluntary contraction task. Fourteen healthy subjects, seven males and seven females, with no history of muscle pain in the masticatory system participated in this study. This protocol was repeated three times, but in the second trial, the cold pressor stimulation was applied to the subject during and for 5 min after the sustained contraction task. Repeated-measure analysis of variance performed on these data revealed that the peak hemoglobin concentration levels in the post-contraction recovery period were significantly reduced (between 13 and 14%) with cold pressor stimulation, both in the masseter (p < 0.001) and in the temporalis (p < 0.001) muscles. The results suggest that cold pressor stimulation produced a reduced intramuscular vasodilative response in these muscles during the immediate post-contraction period. One explanation for these results is that altering the local chemical environment of the muscle affects the adrenergic response pattern typically induced by a cold pressor stimulation.

Adult↗
PubMed1998

Difference in the mechanism of balancing-side disclusion between 1st and 2nd molars.

This study investigates the cusp angle and movement variables related to balancing-side disclusion and compares the characteristics between the 1st and 2nd molar regions. Fifty-six normal young adults were divided into two groups according to balancing-side contact: a disclusion group consisting of 40 subjects (80 excursions), and a non-disclusion group consisting of 16 subjects (20 excursions). Lateral excursions were measured in six-degrees of freedom, and the inclinations of the frontal paths were calculated on the working-side canine, balancing-side 1st and 2nd molars and balancing-side condylar point. The cusp angle was measured using a three-dimensional digitizer. While there were no differences between disclusion and non-disclusion groups in the inclination of the balancing-side condylar path, significant differences were found in the cusp angle and the inclination of the working-side canine path. In the non-disclusion group, the cusp angle of the 2nd molar was markedly greater than that of the 1st molar. It was concluded that the inclination of the anterior guidance and the cusp angle of related teeth have a great effect on the occurrence of balancing-side disclusion and that the mechanism of high frequent balancing-side contacts at the 2nd molar was characterized by its greater cusp angle compared to the 1st molar.

Adult↗
PubMed1997

Halothane inhibition of acetylcholine-induced relaxation in rat mesenteric artery and aorta.

PURPOSE: The effect of halothane was compared on acetylcholine (ACh)-induced relaxation of the mesenteric artery and the aorta in rats. METHODS: The responses of isolated rat aortic and mesenteric arterial ring segments precontracted with phenylephrine to ACh (10(-8)-10(-5) M), in the presence of halothane 0-3%, were compared using isometric force tension recordings. Effects of NG-nitro-l-arginine (L-NOARG, 3 x 10(-5), methylene blue (MB, 5 x 10(-6) M), oxyhaemoglobin in (OxyHB, 10(-7) M), and various potassium channel inhibitors; tetraethylammonium (TEA, 10(-5) M, 10(-3) M), apamin (AP, 10(-7) M), charybdotoxin (ChTx, 10(-7) M) and glibenclamide (GC, 10(-5) M) on ACh-induced relaxation in mesenteric artery were tested. Using radioimmunoassay, ACh (10(-6) M)-induced guanosine 3':5'-cyclic monophosphate (cGMP) accumulation of mesenteric arterial rings pretreated with L-NAORG were also measured. RESULTS: L-NOARG partially inhibited ACh-induced relaxation in mesenteric arterial rings (P < 0.05, maximum relaxation reduced by approximately 50%), whereas it abolished them in aortic rings. The remaining relaxation resistant to L-NOARG in mesenteric arterial rings was insensitive to additional MB or OxyHB, and was not accompanied by increases in cGMP contents of rings. Halothane inhibited endothelium-dependent relaxation in aorta and mesenteric arterial rings. This inhibitory effect was larger in aorta. Halothane also inhibited NO independent EDHF-dependent relaxation in the mesenteric arterial rings, CONCLUSION: Despite a similar inhibitory effect on the EDHF relaxing pathway, halothane has a larger effect on endothelium-dependent relaxation in the aorta (NO dependent mainly) than in the mesenteric rings (NO and EDHF dependent).

Acetylcholine↗
PubMed1997

The validity and utility of disease detection methods and of occlusal therapy for temporomandibular disorders.

Our evaluation of the clinical usefulness or devices for the diagnosis or treatment of temporomandibular disorders (TMD) led to the conclusion that the only current gold standard for TMD is a global clinical examination, because none of the instruments can be said to provide more than ancillary documentation and none have proven diagnostic validity or utility. Regarding the therapeutic efficacy of occlusal adjustment, we could find no comparative studies that test the efficacy of occlusal adjustment in preventing TMD. The studies we reviewed on the relationship of occlusion to TMD are not convincing, powerful, or practical enough to make any recommendations about a causal association.

Centric Relation↗
PubMed1997

Effect of occlusal splint on masticatory movement in healthy individuals.

To investigate the effects of wearing an occlusal splint on masticatory movements in healthy individuals, twelve healthy individuals were examined. A full maxillary stabilization splint made of heat-cured acrylic resin was fabricated for, and worn by, each individual for 24 hours. Masticatory movement was measured before and after the 24-hour period using a 3-D mandibular movement analyzing system. While the duration of a masticatory cycle+ did not change, the occlusal time significantly decreased after use of the splint. The lateral displacement of the opening phase to the balancing-side area also decreased after use of the splint, showing a vertical pattern of the opening path. Measurement in more healthy individuals and patients should help clarify the therapeutic mechanism of the splint in the treatment of temporomandibular disorders.

Adult↗
PubMed1996

A beta-adrenoceptor agonist evokes a nitric oxide-cGMP relaxation mechanism modulated by adenylyl cyclase in rat aorta. Halothane does not inhibit this mechanism.

BACKGROUND: The objective of this study was to characterize the effects of halothane on the agonist-induced nitric oxide-cyclic GMP (NO-cGMP) mechanisms by comparing the intracellular signal transduction mediating isoproterenol- and acetylcholine-induced nitric oxide formation. METHODS: Isoproterenol-induced relaxations of rat aortic rings with and without endothelia were examined in the absence and presence of halothane. Studies were also done in the presence of inhibitors of nitric oxide-synthase, adenylyl cyclase, calmodulin, protein kinase A, and intracellular Ca2+ release mechanism. The relaxations under some of these conditions were compared with those induced by acetylcholine. Cyclic nucleotide contents of the rings were also measured. RESULTS: Isoproterenol relaxed aortic rings via the endothelium-dependent nitric oxide-cyclic GMP mechanism. Inhibition of adenylyl cyclase or of protein kinase A attenuated the isoproterenol-induced relaxations significantly but did not affect those induced by acetylcholine. Inhibition of intracellular Ca2+ release abolished the acetylcholine-induced relaxations but did not affect those induced by isoproterenol. Calmodulin inhibition attenuated both agonist-induced relaxations significantly. Unlike acetylcholine-induced relaxation, that induced by isoproterenol was not affected by halothane. Isoproterenol increased both the cyclic adenosine monophosphate and cGMP contents of rings significantly when endothelia were intact. Inhibition of nitric oxide synthase attenuated the isoproterenol-induced cGMP content increases significantly but did not affect the cyclic adenosine monophosphate content increases. Halothane (2%) did not affect isoproterenol-induced increases in nucleotide content. CONCLUSIONS: Isoproterenol-induced nitric oxide formation requires the activation of constitutive nitric oxide synthase, but the Ca2+ release mechanism is not involved in activating this enzyme. Halothane can inhibit the nitric oxide-cyclic GMP mechanism only when Ca2+ release is greatly involved in the activation of constitutive nitric oxide synthase.

Acetylcholine↗
PubMed1993

A patient with hepatocellular carcinoma who underwent resection of the primary lesion 10 years ago and resection of a giant adrenal metastasis 8 and a half years later.

A 56-year-old male consulted us because of a palpable mass and pain of the left flank 8 and a half years after resection of hepatocellular carcinoma of the left lobe about 3 cm in diameter. Ultrasound examination of the abdomen demonstrated a tumor about 10 cm in diameter showing a mosaic of hyperechoic and hypoechoic areas on the upper pole of the left kidney. By angiography, the tumor was found to be supplied mainly by the inferior adrenal artery. PIVKA-II was increased. Adrenal metastasis of hepatocellular carcinoma was suspected, and adrenalectomy was carried out. No intrahepatic metastasis was noted. The tumor was histopathologically identified as a pseudo-glandular type of moderately differentiated hepatocellular carcinoma with a trabecular pattern similar to the primary lesion. In this patient, a resectable giant metastasis was observed only in the left adrenal gland and no intrahepatic metastasis was demonstrated 8 and a half years after resection of hepatocellular carcinoma. The patient has survived 10 years after the first operation. This case is considered to be important for evaluation of the treatment for distant metastasis of hepatocellular carcinoma.

Adrenal Gland Neoplasms↗