Bronchogenic cyst in the abdomen

A bronchogenic cyst was found in the abdomen, in the retroperitoneum adjacent to the superior pancreatic body. The cyst was unilocular and contained about 100 ml pale yellow mucinous fluid. Microscopic examination revealed a pseudostratified columnar ciliated or cuboidal epithelium, seromucous glands, smooth muscle and cartilage, the distinctive features of bronchogenic cysts. This aberrant location of the cyst is explicable if abnormal buds of the tracheobronchial tree are pinched off and migrate into the abdomen in an early embryonic stage before the canal linking the abdominal with the thoracic cavity is closed by fusion of the future components of the diaphragm.

Plasminogen activator system in human breast cancer

We measured antigen levels of 2 kinds of plasminogen activator, tissue-type plasminogen activator (t-PA) and urokinase-type plasminogen activator (UK), as well as those of their primary inhibitors, type-I plasminogen activator inhibitor (PAI-1) and type-2 plasminogen activator inhibitor (PAI-2), in tissue extracts from benign and malignant breast tumors. Tumor tissue samples from 40 fibroadenomas and 40 breast cancers were examined. t-PA antigen levels were the same in the 2 groups. Malignant tumors contained higher levels of UK antigen than did benign tumors. In the case of breast cancer, UK antigen levels of tumors with axillary lymph-node involvement were significantly higher than those of tumors without lymph-node involvement. PAI-1 and PAI-2 antigen levels of breast-cancer tissue samples were higher than those of fibroadenoma samples. PAI-1 antigen levels of carcinomas with lymph-node involvement were also significantly higher than those of carcinomas without node involvement. PAI-2 antigen levels, on the contrary, were higher in carcinomas without node involvement. UK, PAI-1 and PAI-2 antigen levels are potentially excellent independent factors for prediction of the metastatic potential of breast cancers.

Elastofibromatous lesion of the stomach in a patient with elastofibroma dorsi

A 69-year-old woman underwent partial gastrectomy because of peptic ulcer which resisted medical treatment. The resected stomach exhibited a wide thickening of the antral wall around a 1.2 X 0.8 cm ulcer. The cut surface showed a gray-white thickened submucosal layer and had a rubbery elastic consistency. Microscopically, the thickened areas consisted of abundant acellular collagen fibers containing numerous elastinophilic, thick, serrated fibers and globules, identical with the elastofibroma fibers seen in elastofibroma dorsi. Reexamination of the patient revealed bilateral subscapular masses; one of these was biopsied and proved to be an elastofibroma dorsi.

Prospective randomized study of hyperthermia combined with chemoradiotherapy for esophageal carcinoma

From January 1988 to June 1992, 66 patients with resectable squamous cell carcinoma of the thoracic esophagus underwent preoperative adjuvant therapy. These patients were prospectively divided into two treatment groups; 32 were treated with radiofrequency wave local hyperthermia combined with chemoradiotherapy (hyperthermochemoradiotherapy; HCR), while the remaining 34 patients were treated with chemoradiotherapy alone (CR). There were no procedural complications in either group and the postoperative mortality was zero. In the HCR group, no viable cancer cells were found within the entire 5 mm-width slices of the resected specimen in eight patients (25%), while only two (5.9%) in the CR group (P < 0.05) demonstrate no viable cancer cells. The cumulative 3-year survival rate was 50.4% in the HCR group and 24.2% in the CR group. The present prospective trial demonstrated that the addition of hyperthermia to chemoradiotherapy resulted in a better local control and an improved long-term survival when treating patients with advanced esophageal carcinoma.

Impact of recent advances in hepatobiliary imaging techniques on the preoperative diagnosis of carcinoma of the gallbladder

Among 26 patients with gallbladder carcinoma, 11 resected cases were studied retrospectively with respect to the preoperative imaging techniques and the operative procedures employed. Ultrasonography, endoscopic ultrasonography, and computed tomography were valuable in detecting gallbladder carcinoma preoperatively while direct cholangiography and angiography were helpful in designing operative strategy. The ultrasonographic findings were: a polypoid (fungating) mass protruding into the gallbladder lumen in 45%, abnormal thickening of the gallbladder wall in 18%, and a mass in the gallbladder invading adjacent organs in 18% of cases. Approximately 80% was diagnosed preoperatively by ultrasonography. Correct diagnosis was made by computed tomography in 60% of the cases. Endoscopic ultrasonography offered valuable information on the depth of tumor invasion. Direct cholangiography and angiography were useful in assessing the extent of the tumor spread. Recent advances in hepatobiliary imaging techniques, especially ultrasonography and computed tomography, contributed greatly to the detection and evaluation of gallbladder carcinoma at an early and resectable stage.

Protein microarray analysis identifies human cellular prion protein interactors

AIMS

To obtain an insight into the function of cellular prion protein (PrPC), we studied PrPC-interacting proteins (PrPIPs) by analysing a protein microarray.

METHODS

We identified 47 novel PrPIPs by probing an array of 5000 human proteins with recombinant human PrPC spanning amino acid residues 23-231 named PR209.

RESULTS

The great majority of 47 PrPIPs were annotated as proteins involved in the recognition of nucleic acids. Coimmunoprecipitation and cell imaging in a transient expression system validated the interaction of PR209 with neuronal PrPIPs, such as FAM64A, HOXA1, PLK3 and MPG. However, the interaction did not generate proteinase K-resistant proteins. KeyMolnet, a bioinformatics tool for analysing molecular interaction on the curated knowledge database, revealed that the complex molecular network of PrPC and PrPIPs has a significant relationship with AKT, JNK and MAPK signalling pathways.

CONCLUSIONS

Protein microarray is a useful tool for systematic screening and comprehensive profiling of the human PrPC interactome. Because the network of PrPC and interactors involves signalling pathways essential for regulation of cell survival, differentiation, proliferation and apoptosis, these observations suggest a logical hypothesis that dysregulation of the PrPC interactome might induce extensive neurodegeneration in prion diseases.

Pathology of carcinoma of the gallbladder

A clinicopathologic study of 40 cases of carcinoma of the gallbladder is presented. Twenty-six cases resected were assessed retrospectively with respect to the operative procedures employed and the results based on the pathologic findings from the resected specimens. The relationship between clinical features, macroscopic forms of tumor, histological types, liver invasion, and lymph node metastasis were investigated. Papillary, papillary infiltrative and nodular forms were classified as either papillary adenocarcinoma or well-differentiated tubular adenocarcinoma and invasion of the liver and lymph node metastasis were rare. Frequent lymph node metastasis was encountered in the nodular infiltrative form and invasion of the liver was frequently present in the infiltrative form. Invasion of the liver, lymph node metastasis, and the presence of gallstones were less frequent in papillary adenocarcinoma. In contrast, moderately-differentiated tubular adenocarcinoma frequently had lymph node metastasis. Invasion of the liver and lymph node metastasis were, however, present regardless of the histologic types and were more related to the extent of subserosal involvement present. A female preponderance was noted in poorly-differentiated adenocarcinoma. The main reasons for surgery being limited to exploratory laparotomy only or palliative procedures included carcinoma infiltration into the hepatoduodenal ligament, carcinoma extension to the neighboring structures, multiple liver metastases, peritoneal dissemination, large liver invasion, and multiple metastases to the paraaortic lymph nodes.

Relationship between preoperative assessment of organ function and postoperative morbidity in patients with oesophageal cancer

OBJECTIVE

To find out if strict assessment of organ function preoperatively predicted morbidity and mortality in patients being operated on for oesophageal carcinoma.

DESIGN

Retrospective study.

SETTING

Teaching hospital, Japan.

SUBJECTS

178 patients operated on for oesophageal cancer 1989-1993.

INTERVENTIONS

Oesophagectomy and reconstruction (using either stomach or colon) in one stage by a right thoracoabdominal approach in 173, and transhiatal resection in 5 with either poor pulmonary reserve or early lesions.

MAIN OUTCOME MEASURES

Correlation between preoperative assessment of organ function and postoperative development of complications.

RESULT

79 patients (44%) developed complications and 6 died (3%). Pulmonary dysfunction preoperatively was significantly associated with the development of all complications (p=0.001) and of postoperative pulmonary complications (p=0.04). No other preoperative assessment correlated significantly with the development of postoperative complications.

CONCLUSION

Accurate preoperative assessment of pulmonary function is a valuable indicator of postoperative morbidity.

Interleukin 4 acts as an inducer of decay-accelerating factor gene expression in human intestinal epithelial cells

BACKGROUND & AIMS

Decay-accelerating factor (DAF) protects host tissues from the attack of autologous complement activation. In this study, we attempted to define the cytokine regulation of DAF messenger RNA (mRNA) expression in human intestinal epithelial cells.

METHODS

The effects of cytokines on DAF mRNA accumulation were evaluated by Northern blot analysis. The DAF protein expression was analyzed by both immunoprecipitation and immunoblotting.

RESULTS

Interleukin (IL)-4 induced a marked increase in DAF mRNA accumulation in HT-29 cells. In this line, IL-1 beta evoked only weak induction, and IL-6, IL-8, IL-10, and interferon gamma had no effect. The effect of IL-4 was observed in a dose-dependent manner and confirmed at the protein level. The increase in DAF mRNA accumulation reached a maximum at 3-6 hours and then gradually decreased. These effects of IL-4 on DAF mRNA and protein expression were also observed in T84 cells. The mRNA stability studies suggested that IL-4 regulates DAF gene expression mainly at the transcriptional level.

CONCLUSIONS

In human intestinal epithelial cells, IL-4 acts as a potent inducer of DAF mRNA expression, suggesting a cytoprotective role for IL-4 against autologous complement activation.

Increase in levels of plasminogen activator and type-1 plasminogen activator inhibitor in human breast cancer: possible roles in tumor progression and metastasis

We measured antigen levels of two kinds of plasminogen activators, tissue type plasminogen activator (t-PA) and urokinase type plasminogen activator (UK), as well as their primary inhibitor, type-1 plasminogen activator inhibitor (PAI-1) in the tissue extracts of benign and malignant breast tumors. Tumor tissues of 36 fibroadenomas and 39 breast cancers were examined. t-PA levels were not different in both groups. Malignant tumors contained the significantly higher levels of UK than benign tumors (p less than 0.001). Furthermore in breast cancer tissues, UK antigen levels of tumors with axillary lymph node involvements were significantly higher than those of tumors without lymph node involvements (p less than 0.05). PAI-1 antigen levels of breast cancer tissues were dramatically higher than those of fibroadenoma (p less than 0.001). PAI-1 levels of node positive carcinomas showed also values significantly higher than node negative ones (p less than 0.01). When we divided cancer tissues into three groups as node negative tumors, tumors with positive axillary nodes fewer than four and tumors with four or more positive nodes, PAI-1 levels increased corresponding to the progression of lymph node involvements (p less than 0.05). Immunohistochemical studies, using mouse monoclonal antibodies to human UK and PAI-1, showed that those immunoreactivities were diffusely distributed in the cytoplasm of human breast cancer cells. Their staining patterns were very similar to each other.

The concentration of tissue plasminogen activator and urokinase in plasma and tissues of patients with ovarian and uterine tumors

The concentrations of tissue plasminogen activator (t-PA) and urokinase (UK) were measured in the plasma of patients with benign or malignant ovarian and uterine tumors. Plasma levels of t-PA were higher in patients with malignant ovarian and uterine tumors than in patients with benign tumors. Plasma UK levels were, however, not different between patients with ovarian and uterine tumors (benign or malignant) and normal persons. The concentrations of t-PA and UK of tissues of uterine myoma were lower than those in normal uterine muscular layer. UK levels of tissues of endometrial and cervical cancers were significantly higher than those in normal endometrium and uterine cervix, whereas t-PA levels were not different between these tumors compared with those in normal uterine tissues.

Pancreatic Schwannoma: report of a case

We present herein a case of solitary schwannoma of the pancreas and also review 26 previously reported cases from the English and Japanese literature. Primary schwannoma of the pancreas is a rare tumor. A 50-year-old female was discovered to have a large mass in the upper abdomen on ultrasonography. An examination by computed tomography (CT) scan, magnetic resonance imaging (MRI), and ultrasonography revealed a solid and cystic tumor in the left upper quadrant of the abdomen. A distal pancreatectomy with a splenectomy was performed to remove this tumor. A microscopic examination identified the tumor to be situated in the pancreas while it was composed of cells that originated from Schwann cells. Only 26 cases of pancreatic schwannoma have previously been reported in the English and Japanese literature. We describe in detail the characteristic findings based on image analyses, including CT scan, MRI, ultrasonography, and angiography, in these 26 cases.

Efficacy and safety of nurse-administered propofol sedation during emergency upper endoscopy for gastrointestinal bleeding: a prospective study

BACKGROUND AND STUDY AIMS

Recent studies have documented the safety of propofol sedation for endoscopic procedures, but many endoscopists are reluctant to use propofol for high-risk patients because of adverse effects. The aim of this study was to demonstrate the safety and efficacy of nurse-administered propofol sedation during emergency upper endoscopy for patients with gastrointestinal bleeding.

PATIENTS AND METHODS

Over a period of 18 months, 120 patients suffering from acute upper gastrointestinal bleeding received propofol sedation administered by a registered nurse. Among these, 15 patients were classified into American Society of Anesthesiologists (ASA) class IV, 84 were ASA class III, and 21 were ASA class II. Patients without gastrointestinal bleeding, who also received propofol during the same period and were matched for age, gender, and ASA class, served as controls.

RESULTS

Endoscopic hemostasis was achieved in 98.3 % of patients, and 97.5 % were satisfied with the procedure. In patients with gastrointestinal bleeding, the rates of hypotension (systolic blood pressure < 90 mmHg) and hypoxemia (peripheral oxygen saturation < 90 %) were 8.3 % and 6.7 % respectively, values higher than those in the control group. However, neither mask ventilation nor endotracheal intubation was necessary. Although two patients with gastrointestinal bleeding developed pneumonia, most likely due to aspiration during the procedure, they recovered within 5 days of treatment. There were no sedation-associated severe complications or mortalities.

CONCLUSION

Using a strict protocol designed to protect the patient's airway and cardiovascular function, nurse-administered propofol sedation during emergency upper gastrointestinal endoscopy is safe and appropriate in cases of acute gastrointestinal bleeding.

Tumour necrosis factor-alpha up-regulates decay-accelerating factor gene expression in human intestinal epithelial cells

The increased expression of decay-accelerating factor (DAF) has been detected in intestinal epithelial cells at the inflamed mucosa. In this study, we examined the effects of tumour necrosis factor (TNF)-alpha on DAF expression in three intestinal epithelial cell lines. DAF mRNA expression was evaluated by Northern blot analysis, and DAF protein expression was analysed by biotin labelling and immunoprecipitation. TNF-alpha induced a marked increase in DAF mRNA and protein expression in HT-29, T84 and Caco-2 cells. In HT-29 cells, the effects of TNF-a on DAF mRNA accumulation were observed in a dose-dependent manner; DAF mRNA accumulation reached a maximum at 3-6 hr, and then gradually decreased. These effects of TNF-alpha required de novo protein synthesis. Messenger RNA stability studies suggested that TNF-alpha partially regulated DAF gene expression by a posttranscriptional mechanism. Moreover, the combination of TNF-alpha and interleukin (IL)-4 induced an additive increase in DAF mRNA accumulation in HT-29 and T84 cells. In human intestinal epithelial cells, TNF-alpha acts as a potent inducer of DAF mRNA expression, indicating an important role for TNF-alpha in the regulation of DAF expression at the inflamed mucosa.

Transforming growth factor-beta1 suppresses atopic dermatitis-like skin lesions in NC/Nga mice

BACKGROUND

Atopic dermatitis is a chronic, relapsing inflammatory disorder characterized by pruritic and eczematous skin lesions. Transforming growth factor (TGF)-beta1 has been implicated in the suppression of inflammatory responses.

OBJECTIVE

The purpose of this study is to determine whether TGF-beta1 suppresses skin lesions in a mouse model of atopic dermatitis.

METHODS

We used the NC/Nga strain of mice as an in vivo model of atopic dermatitis. The effects of exogenous TGF-beta1 on atopic dermatitis-like skin lesions in NC/Nga mice were evaluated clinically, histologically and immunologically.

RESULTS

Subcutaneous injection of recombinant TGF-beta1 macroscopically suppressed eczematous skin lesions in NC/Nga mice associated with reduced serum immunoglobulin E (IgE) levels. Histological analysis showed that TGF-beta1 significantly inhibited the infiltration of inflammatory cells such as mast cells and eosinophils into the skin of NC/Nga mice. Spontaneous interferon (IFN)-gamma production from splenocytes of NC/Nga mice was down-regulated by the treatment with TGF-beta1 and neutralizing antibody against IFN-gamma inhibited skin lesions in NC/Nga mice. The inhibitory effect of TGF-beta1 on the skin lesions lasted at least 1 week after cessation of the treatment.

CONCLUSION

These findings indicate that TGF-beta1 suppressed atopic dermatitis-like skin lesions in NC/Nga mice at least in part through down-regulation of IFN-gamma. These results suggest that TGF-beta1 may have a therapeutic potential for atopic dermatitis.

Adenosquamous carcinoma of the pancreas: report of two cases

Adenosquamous carcinoma of the pancreas is a rare variant of pancreatic exocrine carcinoma. We herein report two patients with this entity. One patient was a 60-yr-old Japanese man complaining of a palpable mass, 5.5 cm in the greatest diameter, in the epigastrium. Serum CA 19-9 was increased (2010 U/ml). Ultrasonography and computed tomography showed a mass in the pancreatic tail with central necrosis and invading the posterior wall of the stomach. Angiography showed an encasement of the splenic artery and complete obstruction of the splenic vein. Distal pancreatectomy, splenectomy, and partial resection of the stomach were done. The patient died of uncontrolled bleeding from the duodenal ulcer four months after operation. The other patient was a 73-yr-old man who presented with jaundice. The CA 19-9 was also elevated (354.8 U/ml). Ultrasonography showed a pancreatic head mass of heterogeneous echogeneity and computed tomography demonstrated a cystic mass with an enhanced rim, indicating necrosis in the tumor center. Angiography showed a hypervascular mass in the head of the pancreas. Pylorus-preserving pancreatoduodenectomy was done, but the patient died of multiple liver metastases 10 months after the operation. From our experience with the two patients, the presence of central necrosis in an infiltrative huge pancreatic tumor seems to be suggestive of the diagnosis of adenosquamous carcinoma of the pancreas.

Local secretion of complement C3 in the exocrine pancreas: ductal epithelial cells as a possible biosynthetic site

BACKGROUND & AIMS

The complement system participates in the local immune system in various tissues. In this study, we investigated the local secretion of complement C3 into the pancreatic fluid and attempted to determine a possible biosynthetic site.

METHODS

C3 protein in human pancreatic fluid was analyzed by, immunoblotting. The C3 messenger RNA (mRNA) expression in several pancreatic carcinoma cell lines was analyzed by the polymerase chain reaction and/or Northern blotting. The secretion of C3 by these pancreatic carcinoma cells was assessed by metabolic labeling and immunoprecipitation experiments.

RESULTS

In five samples of human pancreatic fluid, C3 was detected as a molecule composed of alpha and beta chains. C3 mRNA expression was observed in the ductal cell carcinoma lines (PANC-1 and MIA PaCa-2) but not in the acinar cell line (HPC-YO and AR-42J). C3 production in these cells was enhanced by interleukin 1 beta and tumor necrosis factor alpha at both the protein and the mRNA levels.

CONCLUSIONS

(1) Complement C3 is secreted into the exocrine fluids of the pancreas. (2) Ductal epithelial cells are possible biosynthetic sites for C3. (3) The proinflammatory cytokines, interleukin 1 beta and tumor necrosis factor alpha are effective stimulators of local C3 production in the pancreas.

Pressure-pain threshold determination in the oral mucosa: validity and reliability

Fundamental knowledge of pain in the oral mucosa is lacking. We determined the validity and reliability of the pressure-pain threshold (PPT) measurement in the oral mucosa using a newly developed hand-held pressure algometer. Ten dentulous subjects were recruited, and the PPT was measured at the bilateral buccal (on the attached gingiva apical to the midline of the upper first premolars, 3 mm from the mucogingival junction) and the palatal sites (mid-point between the bilateral upper first molars). The PPT linearly increased with an increase in load-rate (P < 0.0001). The PPT yielded a high intra-individual stability both for the same-day consecutive trials and weekly sessions. The palatal site revealed a 4- to 4.65-fold greater PPT than the buccal sites (Bonferroni, P < 0.0001), whereas no difference was found between the bilateral buccal sites (P=0.663). Despite a great interindividual variation in the PPT, significant intra-individual correlations were found among the measurement sites. This suggested differences in individual sensitivity to pain in the oral mucosa, which may determine overall pain sensation specific to an individual. A pressure algometer described herein reliably assessed the PPT in the oral mucosa and sensitively discriminated PPT differences at different sites and at different load-rates, suggesting the reliability and validity of PPT measurements in the oral mucosa for clinical and research investigations.

Carcinogenesis and histogenesis of esophageal carcinoma

Dysplasia is one of the most important subjects regarding carcinogenesis of the esophagus, because there is continuing controversy as to whether esophageal dysplasia is a cancerous lesion or a noncancerous lesion. In this study, it is histopathologically shown that dysplasia has a close correlation with cancer itself and that there is no substantial difference in the cell proliferative activity of dysplasia and intraepithelial carcinoma. These findings thus show that dysplasia has as high a potential for malignancy, thus it should be treated as an extremely early cancerous lesion of the esophagus to substantially improve the long term results of this disease. Conversely, esophageal carcinoma with glandular and/or mucus-secreting components is commonly found in addition to the ordinary component of squamous cell carcinoma, which indicates that this type of esophageal tumor originates not only from the squamous epithelium but also from the esophageal mucus gland or the ductal epithelium. These findings support the concept of field carcinogenesis in esophageal carcinoma.

What is the earliest malignant lesion in the esophagus?

BACKGROUND

The incidence of early esophageal cancer is definitely increasing due to recent advances in diagnostics. When we discuss early carcinoma of the esophagus, however, there is still controversy as to whether dysplasia is either benign or the earliest malignant lesion.

METHODS

Nineteen resected esophaguses with both cancer and dysplasia (including 19 cancers concomitant with 26 dysplastic lesions) were studied for expression of p53 protein.

RESULTS

Immunohistochemical overexpression of p53 protein in esophageal dysplasia is almost the same as that in cancer.

CONCLUSIONS

Esophageal dysplasia should be recognized as the earliest malignant lesion which already demonstrates cancerous features although it is not immediately critical. A routine endoscopic Lugol's solution test is very useful for both detection and following-up of the early nests in the esophagus. These lesions are good candidates for endoscopic mucosal resection for the purpose of accurate diagnosis or curative treatment.

Effect of perioperative pain neuroscience education in patients with post-mastectomy persistent pain: a retrospective, propensity score-matched study

PURPOSE

Central sensitization (CS)-related symptoms and pain catastrophizing contribute to persistent post-mastectomy pain (PPMP). Pain neuroscience education (PNE) is effective in reducing CS-related symptoms and pain catastrophizing in patients with chronic pain. However, to date, no intervention study of PNE has been conducted to patients with PPMP. This study was aimed to examine whether PNE is more effective than biomedical education (BME) for PPMP.

METHODS

In this retrospective case-control study, 118 patients were included. We intervened different patients at different times as follows: (1) a BME group (n = 58) of patients who received BME combined with physiotherapy and (2) a PNE group (n = 60) of patients who received PNE combined with physiotherapy. One year after surgery, we assessed pain intensity and interference (brief pain inventory [BPI]), CS-related symptoms (central sensitization inventory [CSI]), and pain catastrophizing (pain catastrophizing scale [PCS]). Propensity score matching was used to reduce or minimize selection bias and confounding biases and to make the number of cases in both groups match 1:1.

RESULTS

Propensity score matching generated the BME group (n = 51) and the PNE group (n = 51). The BPI score, CSI score, and PCS score were statistically significantly lower in the PNE group than in the BME group (all, p < 0.05). The effect sizes for the BPI intensity (r = 0.31) were moderate.

CONCLUSIONS

PNE resulted in a better outcome of pain management with less functional disability and CS-related symptoms compared to BME after breast surgery.

Gap-junction-mediated Communication in Human Periodontal Ligament Cells

Periodontal tissue homeostasis depends on a complex cellular network that conveys cell-cell communication. Gap junctions (GJs), one of the intercellular communication systems, are found between adjacent human periodontal ligament (hPDL) cells; however, the functional GJ coupling between hPDL cells has not yet been elucidated. In this study, we investigated functional gap-junction-mediated intercellular communication in isolated primary hPDL cells. SEM images indicated that the cells were in contact with each other via dendritic processes, and also showed high anti-connexin43 (Cx43) immunoreactivity on these processes. Gap-junctional intercellular communication (GJIC) among hPDL cells was assessed by fluorescence recovery after a photobleaching (FRAP) analysis, which exhibited dye coupling between hPDL cells, and was remarkably down-regulated when the cells were treated with a GJ blocker. Additionally, we examined GJs under hypoxic stress. The fluorescence recovery and expression levels of Cx43 decreased time-dependently under the hypoxic condition. Exposure to GJ inhibitor or hypoxia increased RANKL expression, and decreased OPG expression. This study shows that GJIC is responsible for hPDL cells and that its activity is reduced under hypoxia. This is consistent with the possible role of hPDL cells in regulating the biochemical reactions in response to changes in the hypoxic environment.