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Biomedical subjects

Masao Tanaka

Publications and source records attributed to Masao Tanaka.

At least 19 recordsLinked to original sources

Hedgehog signaling pathway is a possible therapeutic target for gastric cancer.

BACKGROUND AND OBJECTIVES: It has been shown that the hedgehog (Hh) signaling pathway is activated in gastric cancer. To investigate the viability of the Hh pathway as a therapeutic target, we analyzed activation of the Hh pathway in gastric cancer. METHODS: Surgically resected gastric carcinoma specimens and lymph nodes were analyzed immunohistochemically. We used the percentage of cancer cells with nuclear translocation of Gli1 as a marker of Hh pathway activation. RESULTS: Nuclear localization of Gli1 was higher in 28 undifferentiated-type tumors than in 30 differentiated-type tumors. Eighteen of the fifty-eight cancer specimens consisted of a mixture of a histologically predominant part and a small area with different histology. In these 18 tumors, the percentage of cells showing nuclear staining of Gli1 was higher in the undifferentiated-type part than in the differentiated-type part. Nuclear staining of Gli1 in primary tumors was positively correlated with lymph node metastasis. The Gli1 nuclear staining percentage of metastatic lymph nodes correlated closely with that of each primary carcinoma. Cyclopamine, a Hh pathway inhibitor, suppressed the growth of gastric cancer cells in vitro. CONCLUSIONS: The Hh pathway may be a useful therapeutic target for such as undifferentiated-type gastric cancer with lymph node metastasis.

Adenocarcinoma↗

S100A11, a putative tumor suppressor gene, is overexpressed in pancreatic carcinogenesis.

PURPOSE: Recent microarray analyses revealed that expression of S100A11 is up-regulated in pancreatic cancer. The aim of the present study was to evaluate the association of S100A11 with pancreatic carcinogenesis. EXPERIMENTAL DESIGN: We measured S100A11 mRNA expression in various clinical samples related to pancreatic cancer and its precursor lesions, intraductal papillary mucinous neoplasm (IPMN) and pancreatic intraepithelial neoplasia, by quantitative reverse transcription-PCR. RESULTS: Levels of S100A11 were significantly higher in pancreatic cancer (n=22) and IPMN (n=18) bulk tissues than in nonneoplastic bulk tissues (n=22; P<0.0001 for both). Levels of S100A11 did not differ between pancreatic cancer and IPMN bulk tissues. In microdissection analyses, however, IPMN cells (n=21) expressed significantly higher levels of S100A11 than did cancer cells (n=23; P=0.003). The median level of S100A11 expression was higher in pancreatic intraepithelial neoplasia cells (n=6) than in cancer cells. In pancreatic juice analyses, cancer-related (n=24; P=0.004) and IPMN-related (n=18; P=0.001) juice expressed significantly higher levels of S100A11 than did chronic pancreatitis-related juice (n=23). CONCLUSIONS: The present data suggest that expression of S100A11, a putative tumor suppressor gene, is increased in the early stage of pancreatic carcinogenesis and decreased during subsequent progression to cancer. Analysis of the S100A11 level in pancreatic juice may be an effective tool for screening of patients with high-risk lesions that could progress to pancreatic cancer or detecting early-stage pancreatic cancer.

Carcinoma↗

S100P is an early developmental marker of pancreatic carcinogenesis.

PURPOSE: Our goal was to clarify the involvement and clinical significance of S100P in pancreatic carcinogenesis. EXPERIMENTAL DESIGN: We examined S100P expression in 45 bulk pancreatic tissues; in microdissected cells, including invasive ductal carcinoma (IDC) cells (20 sections), pancreatic intraepithelial neoplasia (PanIN) cells (12 sections), intraductal papillary mucinous neoplasm (IPMN) cells (19 sections), and normal epithelial cells (11 sections); and in pancreatic juice samples from 99 patients with pancreatic diseases (32 cancer, 35 IPMN, and 32 chronic pancreatitis samples). We used quantitative real-time reverse transcription-PCR with gene-specific priming to measure S100P in these various types of samples. RESULTS: In bulk tissue analyses, pancreatic cancer and IPMN expressed significantly higher levels of S100P than did nonneoplastic pancreas (P<0.017 and P=0.0013, respectively). Microdissection analyses revealed that IPMN expressed significantly higher levels of S100P than did IDC (P<0.0001) and PanIN (P=0.0031), although S100P expression did not differ between IDC and PanIN (P=0.077). In pancreatic juice analyses, cancer and IPMN juice expressed significantly higher levels of S100P than did pancreatitis juice (both P<0.0001). Receiver operating characteristic curve analyses revealed that measurement of S100P in pancreatic juice was useful for discriminating neoplastic disease from chronic pancreatitis (area under the curve=0.837; 95% confidence interval, 0.749-0.903). CONCLUSION: S100P may be an early developmental marker of pancreatic carcinogenesis, and measurement of S100P in pancreatic juice may be useful for early detection of pancreatic cancer or screening of early pancreatic carcinogenesis.

Adenocarcinoma, Mucinous↗

Physical activity and colorectal cancer: the Fukuoka Colorectal Cancer Study.

The number of cases of colorectal cancer in Japan has increased over the past few decades, and incidence rates are now among the highest in the world. The present investigation within the Fukuoka Colorectal Cancer Study, including 778 cases and 767 controls aged 20-74 years, examined the association between physical activity and colorectal cancer risk by subsite. Employment-associated and leisure time physical activity was assessed by a questionnaire and interview. Division of sites into the proximal and distal colon, as well as the rectum, revealed clear site-dependent protective effects, with adjustment for smoking, alcohol consumption, BMI and age. In males, greater job-related physical activity was associated with significant reduction of risk in the distal colon and rectum (P = 0.047 and 0.02, respectively), whereas total and moderate or hard non-job physical activity exerted effects limited to the rectum (P = 0.01 and 0.004, respectively). In females, job-related physical activity and moderate or hard non-job physical activity was also protective, but only in the distal colon. Separate assessment of the influence of BMI 10 years previous to the study showed increase in risk with obesity in males but not in females, limited to distal colon and rectum. The results of the present study indicate that physical activity associated with work and leisure-time exerts beneficial effects in Japanese, but not on the proximal colon.

Adult↗

Nuclear factor-kappaB contributes to hedgehog signaling pathway activation through sonic hedgehog induction in pancreatic cancer.

The hedgehog (Hh) signaling pathway, which functions as an organizer in embryonic development, is implicated in the development of various tumors. In pancreatic cancer, pathway activation is reported to result from aberrant expression of the ligand, sonic Hh (Shh). However, the details of the mechanisms regulating Shh expression are not yet known. We hypothesized that nuclear factor-kappaB (NF-kappaB), a hallmark transcription factor in inflammatory responses, contributes to the overexpression of Shh in pancreatic cancer. In the present study, we found a close positive correlation between NF-kappaB p65 and Shh expression in surgically resected pancreas specimens, including specimens of chronic pancreatitis and pancreatic adenocarcinoma. We showed that blockade of NF-kappaB suppressed constitutive expression of Shh mRNA in pancreatic cancer cells. Further activation of NF-kappaB by inflammatory stimuli, including interleukin-1beta, tumor necrosis factor-alpha, and lipopolysaccharide, induced overexpression of Shh, resulting in activation of the Hh pathway. Overexpression of Shh induced by these stimuli was also suppressed by blockade of NF-kappaB. NF-kappaB-induced Shh expression actually activated the Hh pathway in a ligand-dependent manner and enhanced cell proliferation in pancreatic cancer cells. In addition, inhibition of the Hh pathway as well as NF-kappaB suppressed the enhanced cell proliferation. Our data suggest that NF-kappaB activation is one of the mechanisms underlying Shh overexpression in pancreatic cancer and that proliferation of pancreatic cancer cells is accelerated by NF-kappaB activation in part through Shh overexpression.

Animals↗

Overexpression of c-met in the early stage of pancreatic carcinogenesis; altered expression is not sufficient for progression from chronic pancreatitis to pancreatic cancer.

AIM: To investigate c-met expression during early pancreatic carcinogenesis. METHODS: We used 46 bulk tissues and 36 micro-dissected samples, including normal pancreas, chronic pancreatitis, and pancreatic cancer, for quantitative real-time reverse transcription-polymerase chain reaction. RESULTS: In bulk tissue analyses, pancreatic cancer tissues expressed significantly higher levels of c-met than did chronic pancreatitis and normal pancreas tissues. c-met levels did not differ between chronic pancreatitis and normal pancreas tissues. In microdissection-based analyses, c-met was expressed at higher levels in microdissected pancreatic cancer cells and pancreatitis-affected epithelial cells than in normal ductal epithelial cells (both, P < 0.01). Interestingly, pancreatitis-affected epithelial cells expressed levels of c-met similar to those of pancreatic cancer cells. CONCLUSION: Overexpression of c-met occurs during the early stage of pancreatic carcinogenesis, and a single alteration of c-met expression is not sufficient for progression of chronic pancreatitis-affected epithelial cells to pancreatic cancer cells.

Biomarkers, Tumor↗

New rapid detection test with a combination of polymerase chain reaction and immunochromatographic assay for Mycobacterium tuberculosis complex.

Recently, we had developed a polymerase chain reaction (PCR)-immunochromatographic assay (ICA) method for Mycobacterium tuberculosis and examined its clinical utility among 138 sputa of patients under suspicion of pulmonary tuberculosis. According to the results of fluorochrome staining of acid-fast bacillus, which were confirmed by Ziehl-Neelsen staining, these were 83 specimens (-), 7 specimens (+/-), 30 specimens (1+), 8 specimens (2+), and 10 specimens (3+). These specimens included 4 groups: group 1, 41 specimens of smear (+/-) approximately (3+) with culture-positive M. tuberculosis; group 2, 11 specimens of smear (-) with culture-positive M. tuberculosis; group 3, 12 specimens of smear (+/-) approximately (1+) with culture-positive nontuberculosis mycobacterium (NTM); and group 4, 9 specimens of smear (-) with culture-positive NTM. The positive results of PCR-ICA test and Amplicor M. tuberculosis (Amplicor MTB) test for M. tuberculosis are as follows: group 1, 40 positive by PCR-ICA and 39 positive by Amplicor MTB from 41 specimens; group 2, 1 positive by PCR-ICA and 5 positive by Amplicor MTB from 11 specimens; group 3, 0 positive by both tests from 12 specimens; and group 4, 0 positive by both tests from 9 specimens. None of NTM-positive specimens from groups 3 and 4 reacted on the PCR-ICA test for M. tuberculosis.

Bacteriological Techniques↗

Microbiological analysis and endoanal ultrasonography for diagnosis of anal fistula in acute anorectal sepsis.

BACKGROUND AND AIMS: Treatment of anorectal sepsis requires prompt surgical drainage, but it is important to identify any associated anal fistula for preventing recurrence. We evaluated whether microbiological analysis and/or endoanal ultrasonography could be used to predict anal fistula in patients with acute anorectal sepsis. METHODS: Five hundred fourteen consecutive patients with acute anorectal sepsis were studied. Clinical data, digital examination findings, endosonographic findings, and results of microbiological analysis were compared with definitive surgical findings of the presence or absence of anal fistula. RESULTS: Anorectal abscess with anal fistula was found in 418 patients, and anorectal abscess without anal fistula was found in 96 patients. Microbiological examination showed that Escherichia coli, Bacteroides, Bacillus, and Klebsiella species were significantly more prevalent in patients with fistula (P<0.01), and coagulase-negative Staphylococci and Peptostreptococcus species were significantly more prevalent in patients without fistula (P<0.01). Results of endoanal ultrasonography were concordant with the definitive surgical diagnosis in 421 (94%) of 448 patients studied. CONCLUSION: Acute anorectal sepsis due to colonization of "gut-derived" microorganisms rather than "skin-derived" organisms is more likely to be associated with anal fistula. When the microbiological analysis yields gut-derived bacteria, but no fistula has been found in the initial drainage operation, repeat examinations during a period of quiescence, including careful digital assessment and meticulous endosonography, are warranted to identify a potentially missed anal fistula.

Abscess↗

Quantitative analysis of human telomerase reverse transcriptase in pancreatic cancer.

Although telomerase activity is a promising diagnostic marker, clinical introduction of this marker for cancer diagnosis is still problematic due to the lack of means of evaluating sample quality. Human telomerase reverse transcriptase (hTERT), one of the subunits of telomerase, is also a promising diagnostic marker. In the present study, we did large-scale analysis of 88 pancreatic juice samples to determine the feasibility of quantitative analysis of hTERT mRNA for diagnosis of pancreatic cancer. We found significant differences in hTERT expression among carcinoma-derived, intraductal papillary mucinous neoplasm (IPMN)-derived, and chronic pancreatitis-derived juice samples. Results showed that quantitative analyses of hTERT mRNAs are more useful in discriminating carcinoma from IPMN than from chronic pancreatitis. When the specificity was set at 100%, the sensitivity for differentiation between carcinoma and IPMN was 43.5%, whereas the sensitivity of cytologic examination was 22.0%. There were significant differences in hTERT expression among carcinoma cells, IPMN cells, and normal ductal cells isolated from pancreatic tissues by microdissection. Lymphocytes and hyperplastic epithelial cells isolated from tissues with the histologic appearance of pancreatitis showed various expression levels of hTERT. Our results suggest that quantitative analysis of hTERT mRNA in pancreatic juice is advantageous over cytologic analysis for differentiation between carcinoma and IPMN but probably not for differentiation between carcinoma and chronic pancreatitis.

DNA-Binding Proteins↗

Postoperative urinary retention after surgery for benign anorectal disease: potential risk factors and strategy for prevention.

PURPOSE: This study was undertaken to determine the incidence of and risk factors for urinary retention after surgery for benign anorectal disease. METHODS: We reviewed 2,011 consecutive surgeries performed under spinal anesthesia for benign anorectal disease from January through June 2003 to identify potential risk factors for postoperative urinary retention. In addition, we prospectively investigated the preventive effect of perioperative fluid restriction and pain control by prophylactic analgesics on postoperative urinary retention. RESULTS: The number of procedures and the urinary retention rates were as follows: hemorrhoidectomy, 1,243, 21.9%; fistulectomy, 349, 6.3%; incision/drainage, 177, 2.3%; and sliding skin graft/lateral subcutaneous internal sphincterotomy, 64, 17.2%. The overall urinary retention rate was 16.7%. With hemorrhoidectomy, female sex, presence of preoperative urinary symptoms, diabetes mellitus, need for postoperative analgesics, and more than three hemorrhoids resected were independent risk factors for urinary retention as assessed by multivariate analysis. With fistulectomy, female sex, diabetes mellitus, and intravenous fluids >1,000 ml were independent risk factors for urinary retention. Perioperative fluid restriction, including limiting the administration of intravenous fluids, significantly decreased the incidence of urinary retention (7.9 vs 16.7%, P<0.0001). Furthermore, prophylactic analgesic treatment significantly decreased the incidence of urinary retention (7.9 vs 25.6%, P=0.0005). CONCLUSIONS: Urinary retention is a common complication after anorectal surgery. It is linked to several risk factors, including increased intravenous fluids and postoperative pain. Perioperative fluid restriction and adequate pain relief appear to be effective in preventing urinary retention in a significant number of patients after anorectal surgery.

Adult↗

Quantitative analysis of MUC1 and MUC5AC mRNA in pancreatic juice for preoperative diagnosis of pancreatic cancer.

Pancreatic juice is a promising type of diagnostic sample for pancreatic cancer, and members of the mucin (MUC) family are diagnostic candidates. To evaluate the utility of MUC family members as diagnostic markers, we measured MUC mRNA expression in pancreatic tissues and pancreatic juice obtained from patients with different pancreatic diseases as well as in pancreatic cancer cell lines by real-time PCR. Furthermore, to support the possibility of early diagnosis by quantification of MUC1 and MUC5AC, immunohistochemistry and microdissection-based quantitative analysis of mRNA were carried out. There was no significant correlation between MUC1 and MUC5AC expression in cell lines. When beta-actin was used as a reference gene, median MUC1 and MUC5AC mRNA expression levels were remarkably greater in tumoral tissues than in non-tumoral tissues, but median MUC4 and MUC6 mRNA expression levels were not. Receiver operating characteristic curve analysis showed that quantitative analysis of MUC1 and MUC5AC mRNA in pancreatic juice is better diagnostic modality than that of MUC4 and MUC6 mRNA. Immunohistochemistry showed that MUC1 and MUC5AC were highly expressed in invasive ductal carcinomas (IDC) and moderately expressed in high-grade pancreatic intraepithelial neoplasia (PanIN); no staining was observed in normal ducts. Analysis of cells isolated by microdissection showed stepwise upregulation of MUC1 and MUC5AC in the development of high-grade PanIN to IDC. Our results suggest that MUC1 and MUC5AC are upregulated stepwise in pancreatic carcinogenesis and that quantitative assessment of MUC1 and MUC5AC mRNA in pancreatic juice has high potential for preoperative diagnosis of pancreatic cancer.

Biomarkers, Tumor↗

Long-term results of treatment for pancreaticobiliary maljunction without bile duct dilatation.

HYPOTHESIS: Resection of the gallbladder together with the dilated bile duct is the preferred treatment for pancreaticobiliary maljunction (PBM) with bile duct dilatation, whereas this treatment for PBM without bile duct dilatation is still controversial. DESIGN: Retrospective study of 196 patients from January 1979 to November 2004. SETTING: Two university hospitals. PATIENTS: One hundred ninety-six patients with PBM, 152 (78%) with and 44 (22%) without bile duct dilatation, formed the basis of this study. MAIN OUTCOME MEASURES: The effects of cholecystectomy on long-term results in the patients without bile duct dilatation. RESULTS: Significant differences were observed in patients without bile duct dilatation: patients were older, carcinoma of the gallbladder was more prevalent (19 patients [43.2%] without dilatation vs 9 patients [5.9%] with dilatation), and pancreatic cancer and pancreatitis were also more frequent. Most of their gallbladder carcinomas were found at stage IV (63%). The outcome was very poor in stage IV, whereas 5 patients in stage I and II lived for more than 5 years after surgery. Of the 44 patients without bile duct dilatation, 23 with carcinoma of the gallbladder or pancreas died and the other 2 were lost to follow-up. The remaining 19 patients were alive at the study's conclusion after cholecystectomy without bile duct resection. None of them had bile duct carcinoma at the time of surgery or during the mean follow-up period of 9 years after surgery. CONCLUSIONS: Prophylactic cholecystectomy without bile duct resection is the best treatment option for patients with PBM without bile duct dilatation. Possible association of gallbladder carcinoma should be kept in mind at the time of treatment of patients with PBM when the bile duct is not dilated.

Adolescent↗

Gastrointestinal function and quality of life after pylorus-preserving pancreatoduodenectomy.

The pylorus-preserving pancreatoduodenectomy (PPPD) has taken the place of the conventional Whipple pancreatoduodenectomy as the standard procedure for various periampullary disease. With recent advances in surgical techniques and improvements in perioperative management, the number of long-term survivors after PPPD is increasing. As a result, surgeons should pay more attention to the patients' postoperative gastrointestinal function, nutrition, and quality of life (QOL). Gastric stasis, which is a frequent complication during the early postoperative period after PPPD, prolongs the hospital stay and impairs the QOL in the intermediate term. Several possible pathogeneses for this gastric stasis have been postulated; however, the precise mechanism remains unclear. The gastric emptying function gradually recovers to the preoperative level by 6 months after PPPD. Pancreatic functions are likely to be maintained for at least 1 year after PPPD; however, in some cases, they tend to gradually deteriorate over time after the operation, depending on the type of pancreatic reconstruction or the preoperative condition of the pancreas. It is important to note that preoperative and postoperative pancreatic exocrine function strongly influence the postoperative outcome regarding such factors as pancreatic fistula, body weight maintenance, nutrition, and the QOL. The QOL, as assessed by questionnaire, normally returns to the preoperative level within 6 months after PPPD, and this correlates with the changes in gastrointestinal function and nutritional status. It still remains an unresolved question, however, whether the Billroth-I PPPD really leads to better long-term nutritional status, but worse early gastric emptying function, than the Billroth-II type of reconstruction.

Gastric Emptying↗

Type of gastrointestinal reconstruction affects postoperative recovery after pancreatic head resection.

BACKGROUND/PURPOSE: The postoperative recovery of gastric motility with various reconstructions after pancreatic head resection has been reported. However, little is known about this recovery after pancreatic head resection with segmental duodenectomy (PHRSD). Some have attributed gastric stasis after pylorus-preserving pancreatoduodenectomy (PPPD) to tube gastrostomy, but its effect on gastric motility has not been investigated. In this study, the postoperative recovery after PHRSD and PPPD, and gastric motility with and without gastrostomy after PPPD were investigated. METHODS: We analyzed the first appearance of gastric phase III motility, postoperative systemic status, and body weight (BW; n = 32). The Imanaga PPPD and PHRSD were compared because the procedures differ only in the length of the remaining duodenum. Traverso and Roux-en-Y PPPDs were compared because the two procedures are similar except for the creation of gastrostomy. RESULTS: (1) Times to first appearance of gastric phase III motility and BW recovery were significantly better after PHRSD than after the Imanaga PPPD (P < 0.05). (2) Times to first gastric phase III motility and resumption of a regular diet as well as periods of gastric sump tube use and postoperative hospital stay were significantly shorter after the Roux-en-Y than after the Traverso PPPD (P < 0.05). CONCLUSIONS: Preservation of as long a portion of the duodenum as possible, the choice of a Roux-en-Y duodenojejunostomy, and the avoidance of peritoneal fixation of the gastric wall may be factors that improve the recovery of gastric motility and BW after pancreatic head resection.

Adult↗

Complete extirpation of a bronchogenic cyst causing recurrent laryngeal nerve palsy by thoracoscopy: report of a case.

We excised a bronchogenic cyst causing recurrent laryngeal nerve palsy using thoracoscopic surgery. A 28-year-old woman presented after the sudden onset of hoarseness, and laryngoscopic examination showed left vocal cord palsy. Computed tomography and magnetic resonance imaging showed a cystic mass, 4 cm in diameter, in the aortopulmonary window. Thoracoscopic examination revealed that the mass was adhered to the recurrent laryngeal nerve below the aortic arch. We extirpated the cyst via thoracoscopy without any injury to the nerves or major blood vessels. This case illustrates the benefits of thoracoscopic surgery for providing good visualization of the perineural structures and as a safe surgical treatment for a cystic mass in the aortopulmonary window.

Adult↗

Fractalkine in rheumatoid arthritis and allied conditions.

Leukocyte adhesion and trafficking at the endothelium requires both adhesion molecules and chemotactic factors. Fractalkine (CX3C) is a unique chemokine, and is expressed on tumor necrosis factor-alpha- and interleukin-1-activated endothelial cells (ECs). Fractalkine receptor, CX3CR1, is expressed on NK cells, monocytes, and some portion of CD4- and CD8-positive T cells. Interactions between fractalkine and CX3CR1 can mediate not only chemotaxis, but also cell adhesion in the absence of substrates for other adhesion molecules. Furthermore, fractalkine activates NK cells, leading to increased cytotoxicity and interferon-gamma production. Recently, accumulating evidence has shown that fractalkine is involved in the pathogenesis of rheumatoid arthritis and allied conditions. This review examines new concepts underlying fractalkine-mediated leukocyte migration and tissue damage, focusing primarily on the pathophysiological roles of fractalkine in rheumatic diseases.

Arthritis, Rheumatoid↗

Inhibition of inducible nitric oxide synthase prevents hepatic, but not pulmonary, injury following ischemia-reperfusion of rat liver.

The aim of this study was to investigate the contribution of inducible nitric oxide synthase (iNOS)-derived nitric oxide on the liver and lung injury following hepatic ischemia-reperfusion (I/R) using a novel and potent iNOS inhibitor, ONO-1714. Rats were subjected to 90 min of partial hepatic ischemia followed by 3, 6, 12, and 24 hr of reperfusion. Expression of iNOS mRNA peaked at 3 hr of reperfusion in the liver and lung. Plasma nitric oxide levels were increased fourfold at 24 hr of reperfusion and plasma ALT was increased, reaching a peak at 12 hr of reperfusion; both were significantly inhibited by ONO-1714. Histological examination revealed extensive liver damage, whereas this was not seen in the ONO-1714 group. Lung injury was not significantly changed in groups with versus without ONO-1714. Nitrotyrosine expression was seen in regions similar to those of the histological injuries of the liver, while this staining was absent in the ONO-1714 group. These data show that generation of peroxynitrite could be involved in the pathogenesis of liver injury but not lung injury after hepatic I/R. Inhibition of iNOS could be applied for attenuation of liver injury following hepatic I/R.

Amidines↗

The effect of removal of the disc on the friction in the temporomandibular joint.

PURPOSE: The amount of friction in the temporomandibular joint (TMJ) is dependent on the joint components, including the synovial fluid, disc, and articular surface cartilage. As friction in the TMJ is less than in other (discless) joints, we hypothesized that this is caused by the presence of the disc. MATERIALS AND METHODS: The frictional coefficient of the TMJ was first measured in the intact porcine joint (n = 10). After the disc was removed the measurement of frictional coefficient was conducted again. Furthermore, the subsequent effects of loading duration and the application of hyaluronic acid (HA) were examined. RESULTS: The mean frictional coefficient in the intact joint was 0.0177 (SD 0.0021). After disc resection it became 0.0361 (SD 0.0063). The frictional coefficient increased with the length of the preceding loading duration and exceeded 0.0635 (SD 0.0085) after 30 minutes. Subsequent application of HA resulted in a slight decrease of the frictional coefficient. CONCLUSIONS: The presence of the disc reduces the amount of friction in the TMJ. This reduction is likely due to the role of the disc in reducing the amount of incongruity between the articular surfaces and in increasing synovial fluid lubrication.

Animals↗