Clinical Characteristics and Major Adverse Cardiovascular Events in Diabetic and Non-Diabetic Patients with Vasospastic Angina.

Purpose: The clinical background and prognostic impact of diabetes mellitus (DM) on vasospastic angina (VSA) are unclear; thus, in this retrospective study, we investigated whether they differ based on the presence or absence of DM in patients with VSA. Patients and Methods: We included 272 Japanese patients with VSA diagnosed by coronary angiography (CAG) and the spasm provocation test (SPT). The diagnosis of DM was determined by measuring fasting blood glucose and hemoglobin A1C and by the patient's current oral medications. On CAG, the presence of atherosclerotic lesions (20%-50%) was checked. On SPT, the coronary spasm was defined as transient coronary vasoconstriction >90% on CAG, accompanied by chest symptoms and/or ST-T changes. Focal spasm was defined as coronary spasm occurring within one segment of the American Heart Association classification on CAG. Blood and urine tests and vascular endothelial function were also evaluated when possible. A major adverse cardiovascular event (MACE), which is defined as cardiac mortality and rehospitalization due to cardiovascular illness, was the basis for determining the prognosis. Results: There were 49 patients (18%) in the DM group and 223 (82%) in the non-DM group. No significant differences in urinary albumin levels and peripheral vascular function were between groups. On CAG, atherosclerotic lesions were observed significantly more frequently in the DM group (63% vs 46%; P = 0.028). Results of SPT showed a trend toward fewer focal spasms in the DM group (24% vs 39%; P = 0.072). No significant differences in MACE were noted between groups in the primary analysis of DM, whereas sub-analyses of focal spasms showed lower MACE-free survival in the DM group (P = 0.042). Conclusion: The study results support the hypothesis that DM associated with VSA should be treated appropriately, especially in cases of focal spasm, which may require more attention in treatment.

Which Coronary Artery Should Be Preferred for Starting the Coronary Spasm Provocation Test?

BACKGROUND: The spasm provocation test (SPT) is a critical test for diagnosing vasospastic angina (VSA). However, the choice of vessel to be preferred for initiating the SPT-the right coronary artery (RCA) or the left coronary artery (LCA)-is unclear. This study aimed to assess SPT results including SPT-related complications while initiating the SPT in the RCA and LCA. METHODS: We enrolled 225 patients who underwent coronary angiography and SPTs. The SPT was first performed in the RCA in 133 patients (RCA group) and the LCA in 92 patients (LCA group). We defined VSA as >90% narrowing of the coronary artery during the SPT, accompanied by chest pain and/or ST-T changes on the electrocardiogram. When coronary spasm occurs in two or more major coronary arteries, it is referred to as a multivessel spasm (MVS). SPT-related complications comprised atrial fibrillation, ventricular fibrillation, and unstable hemodynamics following catecholamine use. Analyses using propensity score matching (PSM) were performed in 120 patients. RESULTS: No significant differences in the frequencies of VSA and complications were observed between the two groups (RCA: 79% and 19%, respectively; LCA: 85% and 22%, respectively). In both groups, spasms were most frequently provoked in the left anterior descending coronary artery (both p < 0.001) whereas spasms in the left circumflex coronary artery (LCX) were higher in the LCA group than in the RCA group (p = 0.015). Furthermore, no significant difference in the frequency of MVS was observed between both groups (RCA: 50%, LCA: 62%; p = 0.122). After PSM, no significant difference in the frequencies of VSA and complications were observed between the two groups (RCA: 82% and 15%, respectively; LCA: 88% and 18%, respectively). The frequencies of LCX spasms (RCA: 8%, LCA: 23%; p = 0.022) and MVS (RCA: 40%, LCA: 62%; p = 0.020) were higher in the LCA group than in the RCA group. CONCLUSIONS: Although the diagnostic rate of VSA and frequency of SPT-related complications were similar in the two groups, the frequency of MVS was higher in the LCA group than in the RCA group because of the increase in the number of LCX spasms. A routine SPT may be started from the LCA.

Frequency and Clinical Impact of Family History of Coronary Artery Disease in Patients with Vasospastic Angina.

BACKGROUND: Family history (FH) of coronary artery disease (CAD) [FH-CAD] is a well-known risk factor for atherosclerotic CAD. However, FH-CAD frequency in patients with vasospastic angina (VSA) remains unknown, and the clinical characteristics and prognosis of VSA patients with FH-CAD are unclear. Therefore, this study compared FH-CAD frequency between patients with atherosclerotic CAD and those with VSA and examined the clinical characteristics and prognosis of VSA patients with FH-CAD. METHODS: Coronary angiography and spasm provocation tests (SPT) were used to investigate chest pain of coronary artery origin in patients classified into atherosclerotic CAD (362 cases), VSA (221 cases; positive for SPT) and non-VSA (73 cases; negative for SPT) groups, with FH-CAD being defined. In the VSA group, flow-mediated vasodilation (FMD) and nitroglycerin-independent vasodilation (NID) via brachial artery echocardiography and clinical symptoms in the groups with and without FH-CAD were checked, with Kaplan-Meier curves revealing major adverse cardiovascular events (cardiac death and rehospitalisation for cardiovascular disease) between the two groups. RESULTS: The atherosclerotic CAD group had a significantly lower FH-CAD frequency (12%, p = 0.029) than the VSA (19%) and non-VSA groups (19%). FH-CAD was more common in females in the VSA and non-VSA groups than in the atherosclerotic CAD group (p < 0.001). Nonpharmacological treatment for CAD in FH-CAD was more common in the atherosclerotic CAD group (p = 0.017). In the VSA group, FH-CAD tended to be more common in females (p = 0.052). Although no differences in FMD of the brachial artery were observed between the groups, the FH-CAD (+) group had significantly higher NID than the FH-CAD (-) group (p = 0.023). Kaplan-Meier's analysis revealed a similar prognosis between the two groups, and other clinical characteristics did not differ. CONCLUSION: Patients with VSA have a higher FH-CAD frequency than those with atherosclerotic CAD, especially in females. Although FH-CAD may affect vascular function in patients with VSA, its effect on the severity and prognosis of VSA appears to be minimal. FH-CAD and its confirmation may assist in CAD diagnosis, especially in female patients.

Effect of febuxostat on the level of malondialdehyde-modified low-density lipoprotein, an oxidative stress marker: A subanalysis of the PRIZE study.

BACKGROUND: Febuxostat is a selective xanthine oxidase inhibitor that reportedly exhibits antioxidant properties. We previously performed a multicentre, randomized controlled (PRIZE) study for vascular evaluation under uric acid (UA) control by febuxostat to investigate the progression of carotid lesions in asymptomatic hyperuricemic patients with carotid atherosclerosis for 2 years. HYPOTHESIS: The current subanalysis of the PRIZE study aimed to assess the effect of febuxostat on the level of malondialdehyde-modified low-density lipoprotein (MDA-LDL), an oxidative stress marker. METHODS: We recruited 383 patients (febuxostat group, n = 200; control group, n = 183) from the PRIZE trial for whom MDA-LDL measurements were available. The UA, MDA-LDL, low-density lipoprotein cholesterol (LDL-C) levels, and MDA-LDL/LDL-C ratio were identified, represented as the estimated difference from baseline to 24 months. We also evaluated the relationship between febuxostat dose (10, ≤20 to <40, and ≤40 to ≤60 mg) and changes in the MDA-LDL level, LDL-C level, or MDA-LDL/LDL-C ratios. RESULTS: The estimated change in MDA-LDL/LDL-C ratio from baseline to 24 months was significantly lower in the febuxostat group than in the control group (p = .025), whereas the estimated changes in MDA-LDL (p = .235) and LDL-C (p = .323) levels did not differ between the two groups. No significant correlation existed between the febuxostat doses and the estimated change in the MDA-LDL level (p = .626), LDL-C level (p = .896), or MDA-LDL/LDL-C ratio (p = .747). CONCLUSIONS: Our findings may indicate a possibility that febuxostat can lower the MDA-LDL/LDL-C ratio, a potential marker of atherosclerosis and oxidative stress, in asymptomatic hyperuricemic patients with carotid atherosclerosis. Further studies are required to validate our findings and elucidate the clinical antioxidant effect of febuxostat.

Development of an indirect competitive enzyme-linked immunosorbent assay for formononetin and its application in a cell-based assay using MC3T3-E1 cells.

Formononetin (FMN) is a methoxy isoflavone found abundantly in leguminous plants and associated foods. Several analytical methods have been developed to detect FMN. However, they are costly, complicated, and time-consuming. This study describes an indirect competitive enzyme-linked immunosorbent assay (icELISA) to determine FMN content in food samples using a monoclonal antibody (mAb) against FMN produced by a newly established hybridoma cell line. Validation studies were conducted, and this assay was found to be sufficiently reliable, with an analytical measurement range of 19.53-1250 ng/mL and a detection limit of 17.42 ng/mL. Furthermore, icELISA was successfully applied for a cell-based assay in which the amount of FMN and ononin uptake was quantified in MC3T3-E1 cells. Hence, icELISA is a simple and reliable method for the detection and quantification of FMN, as well as elucidation of its functions and underlying mechanisms of action.

Development of Highly Sensitive Chemiluminescence Enzyme Immunostaining Assay to Determine Glycyrrhizin Content Using Anti-glycyrrhizin Monoclonal Antibody.

Licorice, the root of Glycyrrhiza spp., is used in a large number of herbal medicines, such as traditional Chinese medicines, Japanese Kampo medicines, and therapeutic drugs. Since glycyrrhizin (GL) is among the main components in licorice and exhibits numerous beneficial pharmacological activities, the content of GL directly affects biological activity. The quality control based on GL content is an important factor in ensuring biological activity; however, the content of GL in licorice varies depending on plant cultivation environment, genetic factors, and species type. Previously, we prepared an anti-GL monoclonal antibody (anti-GL mAb) and employed it in various immunochemical assays for quality control of licorice and licorice-based products. In this study, we employed the anti-GL mAb in chemiluminescence enzyme immunostaining (CLEIS) to develop a very simple, rapid, specific, and sensitive quality control assay for licorice products, with a limit of detection of 3.9 ng. Furthermore, the CLEIS assay enabled semiquantitative analysis of GL in Kampo medicines. Our results showed that multiple samples can be simultaneously analyzed using CLEIS, and it is a useful tool for determining GL content, as well as ensuring chemical quality control of licorice-containing products and herbal medicines.

Co-ingestion of glutamine and leucine synergistically promotes mTORC1 activation.

Leucine (Leu) regulates protein synthesis and degradation via activation of mammalian target of rapamycin complex 1 (mTORC1). Glutamine (Gln) synergistically promotes mTORC1 activation with Leu via glutaminolysis and Leu absorption via an antiporter. However, Gln has also been shown to inhibit mTORC1 activity. To resolve this paradox, we aimed to elucidate the effects of Gln on Leu-mediated mTORC1 activation. We administered Leu, Gln, tryptophan, Leu + Gln, or Leu + tryptophan to mice after 24-h fasting. The mice were then administered puromycin to evaluate protein synthesis and the gastrocnemius muscle was harvested 30 min later. Phosphorylated eukaryotic initiation factor 4E-binding protein 1, 70-kDa ribosomal protein S6 kinase 1, and Unc-51 like kinase 1 levels were the highest in the Leu + Gln group and significantly increased compared with those in the control group; however, Gln alone did not increase the levels of phosphorylated proteins. No difference in glutamate dehydrogenase activity was observed between the groups. Leu concentrations in the gastrocnemius muscle were similar in the Leu-intake groups. Our study highlights a novel mechanism underlying the promotive effect of Gln on Leu-mediated mTORC1 activation, providing insights into the pathway through which amino acids regulate muscle protein metabolism.

Simultaneous determination of glycyrrhizin and liquiritin in licorice roots and Kampo medicines by combination enzyme-linked immunosorbent assay using anti-glycyrrhizin and anti-liquiritin monoclonal antibodies.

Immunoassay systems using monoclonal antibodies (mAbs) are one of the most useful techniques in the analytical, biochemical, and clinical fields. In this study, a combination enzyme-linked immunosorbent assay (ELISA) using both anti-glycyrrhizin and anti-liquiritin mAbs (anti-GL/Liq mixture mAbs) was developed for quality control of licorice and its products. The combination ELISA demonstrated high sensitivity, reproducibility, and specificity for the total content of GL and Liq by a single assay. The developed ELISA was effective and useful as the first screening method in the selection of high-quality licorice from the Glycyrrhiza species and in confirming the quality of licorice-containing Kampo medicines.

Development of Double Eastern Blotting for Major Licorice Components, Glycyrrhizin and Liquiritin for Chemical Quality Control of Licorice Using anti-Glycyrrhizin and anti-Liquiritin Monoclonal Antibodies.

Licorice is utilized in various food industries around the world for seasoning agents, confectioneries, drinks, and functional foods. Glycyrrhizin (GL) and liquiritin (Liq) are major quality control chemical markers of licorice that have multifunctional bioactivities. Chemical quality control of licorice is important because its component profiles change depending environmental factors (climate, soil condition, and water deficit) and differences between species. Double eastern blotting using anti-GL and anti-Liq monoclonal antibodies was developed for more convenient, rapid, and specific quality control analysis of GL and Liq, respectively. Moreover, double eastern blotting was applied to investigate the immunohistochemical distributions of GL and Liq in the root of fresh licorice; the localization of both components was then clarified visually. This double eastern blotting technique for GL and Liq may serve as a powerful approach for visually determining the chemical quality of licorice.

Case of angina pectoris at rest and during effort due to coronary spasm and myocardial bridging.

We present a case of a 71-year-old male who had chest symptoms at rest and during effort. He had felt chest oppression during effort for 1 year, and his chest symptoms had recently worsened. One month before admission he felt chest squeezing at rest in the early morning. He presented at our institution to evaluate his chest symptoms. Electrocardiography and echocardiography failed to show any specific changes. Because of the possibility that his chest symptoms were due to myocardial ischemia, he was admitted to our institution for coronary angiography (CAG). An initial CAG showed mild atherosclerotic changes in the proximal segment of the left anterior descending coronary artery (LAD) and mid-segment of the left circumflex coronary artery. Subsequent spasm provocation testing using acetylcholine revealed a bilateral coronary vasospasm, which was relieved after the intracoronary infusion of nitroglycerin. Finally, a CAG showed myocardial bridging (MB) of the mid-distal segments of the LAD. Fractional flow reserve using the intravenous administration of adenosine triphosphate was positive at 0.77, which jumped up to 0.90 through the myocardial bridging segments when the pressure wire was pulled back. Thus, coronary vasospasm and MB might have contributed to his chest symptoms at rest and during effort. Interventional cardiologists should consider the presence of MB as a potential cause of myocardial ischemia.

Usefulness of a rotation-revolution mixer for mixing powder-liquid reline material.

PURPOSE: The purpose of this study was to evaluate the distribution of bubbles, degree of mixing, flowability and mechanical strength of powder-liquid reline material by manually and with a rotation-revolution (planetary) mixer, and to determine the usefulness of a rotation-revolution mixer for this application. METHODS: Powder-liquid reline material (Mild Rebaron, GC, Tokyo, Japan) was mixed with a powder to liquid ratio of 1:0.62 according to the manufacturer's instruction. Two methods were used to mix it: mixed by manually ("manual-mixing") and automatically with a rotation-revolution mixer (Super Rakuneru Fine, GC, Tokyo, Japan; "automatic-mixing"). Disc-shaped specimens, 30 mm in diameter and 1.0mm in thickness, were used to observe the distribution of bubbles in at 10× magnifications. Flowability tests were carried out according to the JIS T6521 for denture base hard reline materials. A three point bending test was carried out by a universal testing machine. Elastic modulus and flexural stress at the proportional limit were calculated. RESULTS: A median of 4 bubbles and inhomogeneous were observed in manual-mixed specimens. However, no bubbles and homogeneous were observed in automatic-mixed specimens. Flowability was within the JIS range in all mixing conditions and did not differ significantly across conditions. The elastic modulus was the same for manual-mixed and automatic-mixed specimens. On the other hand, the flexural stress at the proportional limit differed significantly between manual-mixed and automatic-mixed specimens. CONCLUSION: The results confirm that rotation-revolution mixer is useful for mixing powder-liquid reline material. Automatic-mixing may be recommended for clinical practice.

Development of a monoclonal antibody-based immunochemical assay for liquiritin and its application to the quality control of licorice products.

Liquiritin was reacted with a keyhole limpet hemocyanin (KLH) to synthesize a liquiritin-KLH conjugate as an immunogen for mice. A hybridoma cell line named 2F8 secreted a monoclonal antibody (mAb) against liquiritin, which was applied to an enzyme-linked immunosorbent assay (ELISA) for liquiritin. ELISA showed a good linear range from 0.39 to 25 µg/mL of liquiritin. The maximum relative standard deviation (RSD) values for the intra-assay and interassay were approximately 5%. The recovery rates of liquiritin were in the range of 100.9-103.7%, and the concentrations of liquiritin in various licorice roots, as determined by ELISA, showed a good correlation with those analyzed by high-performance liquid chromatography (HPLC; R² = 0.948). These results suggested that ELISA with anti-liquiritin mAb could be a simple, rapid, convenient, and accurate method for the high-throughput analysis of liquiritin in various licorice products including liqueurs, sweets, and food supplements.

Heart failure in which coronary spasms played an important role.

A 69-year-old woman was admitted for further examinations and treatment of chest pain. Emergency cardiac catheterization showed no significant stenosis on coronary angiograms; however, diffuse wall hypokinesis was observed on a left ventriculogram. After treating the patient's heart failure, cardiac catheterization was performed again. A spasm provocation test showed coronary spasms of the right and left coronary arteries. A right ventricular endomyocardial biopsy revealed denaturation and fibrosis of the myocardium under the endocardium, thus suggesting the presence of myocardial ischemia. This case highlights coronary spasms as a cause of heart failure.

Effects of low-energy electron beam irradiation on flexural properties of self-curing acrylic resin.

PURPOSE: The purpose of this study was to confirm the effectiveness of LEB irradiation onto the polymer powder for improving the mechanical properties of self-curing acrylic resin. METHODS: The polymer powder of self-curing acrylic resin was irradiated with total LEB doses of 25, 50, 75 or 100kGy. Non-irradiated powder was used as a control. After LEB irradiation, ESR measurement, weight-average molecular weight measurement and three-point bending test were performed. RESULTS: ESR spectrum of control had no peaks. After LEB irradiation, nine peaks were observed in each ESR spectrum, which indicates the presence of free radicals from main polymer chain. The quantity of free radicals increased linearly up to 100kGy. Calibrated weight-average molecular weights were as follows: control, 960,000; 25kGy, 500,000; 50kGy, 440,000; 75kGy, 410,000; and 100kGy, 390,000. Molecular weight decreased with increasing LEB irradiation dose. The mean values of flexural strength (MPa) were as follows: control, 61.5±3.0; 25kGy, 68.1±4.0; 50kGy, 73.0±1.9; 75kGy, 70.4±3.6; and 100kGy, 67.7±2.3. The flexural strength of the specimens cured with the LEB-irradiated powder was significantly higher than that of control (p<0.01). These results indicate that flexural strength of polymer materials cured with the LEB-irradiated powder increases because of increase in cross-linking structure. CONCLUSION: It is confirmed that LEB irradiation onto the polymer powder of self-curing acrylic resin improves the flexural strength.

Endovascular technique using a snare and suture for retrieving a migrated peripherally inserted central catheter in the left pulmonary artery.

We report a successful endovascular technique using a snare with a suture for retrieving a migrated broken peripherally inserted central catheter (PICC) in a chemotherapy patient. A 62-year-old male received monthly chemotherapy through a central venous port implanted into his right subclavian area. The patient completed chemotherapy without complications 1 mo ago; however, he experienced pain in the right subclavian area during his last chemotherapy session. Computed tomography on that day showed migration of a broken PICC in his left pulmonary artery, for which the patient was admitted to our hospital. We attempted to retrieve the ectopic PICC through the right jugular vein using a gooseneck snare, but were unsuccessful because the catheter was lodged in the pulmonary artery wall. Therefore, a second attempt was made through the right femoral vein using a snare with triple loops, but we could not grasp the migrated PICC. Finally, a string was tied to the top of the snare, allowing us to curve the snare toward the pulmonary artery by pulling the string. Finally, the catheter body was grasped and retrieved. The endovascular suture technique is occasionally extremely useful and should be considered by interventional cardiologists for retrieving migrated catheters.

Microstructural Observation with MicroCT and Histological Analysis of Human Alveolar Bone Biopsy from a Planned Implant Site: A Case Report.

The subject was a 53-year-old male. An alveolar bone sample was obtained from the site of the lower left first molar, before dental implant placement. Although the details of the trabecular structure were not visible with conventional computed tomography, micro-computed tomography (microCT) three-dimensional images of the alveolar bone biopsy sample showed several plate-like trabeculae extending from the lingual cortical bone. Histological observations of the bone sample revealed trabeculae, cuboidal osteoblasts, osteoclasts and hematopoietic cells existing in the bone tissue at the implantation site. Bone metabolic markers and calcaneal bone density were all within normal ranges, indicating no acceleration of the patient's bone metabolism. Using microCT, and histological and histomorphometrical techniques, a great deal of valuable information about the bone tissue was obtained from a biopsy sample extracted from the patient's planned implant site.

Correlations between alveolar bone microstructure and bone turnover markers in pre- and post-menopausal women.

OBJECTIVE: Alveolar cancellous bone biopsy samples were extracted during dental implant preparation for investigating microstructural changes due to menopause and relationships between these changes and bone turnover markers. STUDY DESIGN: Subjects were 18 women receiving mandibular implants: premenopausal (n = 5), early postmenopausal (≤5 years; n = 3), and late postmenopausal (>5 years; n = 10). Bone turnover markers were measured and the samples analyzed using microscopic computerized tomography and 3-dimensional bone morphometry. RESULTS: The alveolar bone volume was significantly less in late postmenopausal women than in premenopausal ones. The trabeculae in early postmenopausal women were more separated and rod-like than in premenopausal ones (P < .05). Each alveolar bone parameter was significantly (P < .05) related to at least 1 bone turnover marker. CONCLUSIONS: Alveolar cancellous bone structure begins changing even in early postmenopausal women, and this structure varies in close relationship to bone turnover markers.

Sequential analysis of head movement during mandibular open-close movements in TMD patients with disc displacement with reduction.

This study examined relationships between starting points of head and mandibular movements in 11 female control subjects and 10 TMD patients showing disc displacement with reduction during consecutive open-close movements, using a six-degree-of-freedom measuring device. During the first mandibular opening cycle, in the TMD group, head movement was significantly preceded in relation to mandibular movement when compared with the control group, and major differences in onset were seen between maximum and minimal values at the beginning of mandibular movements. After the second cycle, significant differences in starting points were not evident. In TMD patients showing disc displacement with reduction, in the first cycle, at the commencement of opening movements, it is proposed that the head precedes the mandible in order to compensate for irregular condylar movements, and the degree of the condylar movement irregularity might affect the onset relation between the head and the mandible.

A dimerization defect caused by a glycine substitution at position 420 by serine in tissue-nonspecific alkaline phosphatase associated with perinatal hypophosphatasia.

Mutations in the tissue-nonspecific alkaline phosphatase (TNSALP) gene cause hypophosphatasia (HPP), an inborn error of metabolism characterized by defects in bone and teeth mineralization accompanying subnormal levels of serum alkaline phosphatase activity. Missense mutations at position 420 of TNSALP (standard nomenclature), which convert glycine to serine [TNSALP (G420S)] or alanine [TNSALP (G420A)], have been reported in perinatal and childhood HPP, respectively. When expressed in COS-1 cells, both TNSALP mutants were indistinguishable from wild-type TNSALP [TNSALP (W)] as evidenced by immunofluorescence and western blotting. Nevertheless, the two TNSALP mutants did not show substantial alkaline phosphatase activity. In agreement with transiently transfected cells, TNSALP (G420S) expressed in a Tet-On inducible expression system lacked its alkaline phosphatase activity, although this mutant was anchored to the cell surface lipid bilayers by glycosylphosphatidylinositol as an 80 kDa mature form bearing complex-type oligosaccharides like TNSALP (W). Importantly, TNSALP (G420S) was found to largely fail to assemble into the homodimer in contrast to TNSALP (W). Taken together, these results demonstrate that the glycine residue at position 420 is crucial for the subunit interaction of TNSALP and hence its catalytic function without affecting trafficking of monomeric TNSALP. We conclude that the dimerization defect is the molecular basis for perinatal HPP associated with the genotype G420S/G420S.

Alterations in intermediate filaments expression in disc cells from the rat temporomandibular joint following exposure to continuous compressive force.

The articular disc in the temporomandibular joint (TMJ) that serves in load relief and stabilizing in jaw movements is a dense collagenous tissue consisting of extracellular matrices and disc cells. The various morphological configurations of the disc cells have given us diverse names, such as fibroblasts, chondrocyte-like cells and fibrochondrocytes; however, the characteristics of these cells have remained to be elucidated in detail. The disc cells have been reported to exhibit heterogeneous immunoreaction patterns for intermediate filaments including glial fibrillary acidic protein (GFAP), nestin and vimentin in the adult rat TMJ. Because these intermediate filaments accumulate in the disc cells as tooth eruption proceeds during postnatal development, it might be surmised that the expression of these intermediate filaments in the disc cells closely relates to mechanical stress. The present study was therefore undertaken to examine the effect of a continuous compressive force on the immunoexpression of these intermediate filaments and an additional intermediate filament - muscle-specific desmin - in the disc cells of the TMJ disc using a rat experimental model. The rats wore an appliance that exerts a continuous compressive load on the TMJ. The experimental period with the appliance was 5 days as determined by previous studies, after which some experimental animals were allowed to survive another 5 days after removal of the appliance. Histological observations demonstrated that the compressive force provoked a remarkable acellular region and a decrease in the thickness of the condylar cartilage of the mandible, and a sparse collagen fiber distribution in the articular disc. The articular disc showed a significant increase in the number of desmin-positive cells as compared with the controls. In contrast, immunopositive cells for GFAP, nestin and vimentin remained unchanged in number as well as intensity. At 5 days after removal of the appliance, both the disc and cartilage exhibited immunohistological and histological features in a recovery process. These findings indicate that the mature articular cells are capable of producing desmin instead of the other intermediate filaments against mechanical stress. The desmin-positive disc cells lacked α-smooth muscle actin (α-SMA) in this study, even though desmin usually co-exists with α-SMA in the vascular smooth muscle cells or pericytes. Because the precursor of a pericyte has such an immunoexpression pattern during angiogenesis, there is a further possibility that the formation of new vessels commenced in response to the extraordinary compressive force.