Fully covered self-expandable metallic stents versus plastic stents for preoperative biliary drainage in patients with pancreatic head cancer and the risk factors for post-endoscopic retrograde cholangiopancreatography pancreatitis

Objectives

Optimal stents for preoperative biliary drainage (PBD) for patients with possible resectable pancreatic cancer remain controversial, and risk factors for post-endoscopic retrograde cholangiopancreatography pancreatitis (PEP), followed by PBD, are unknown. In this study, the efficacy and safety of fully covered self-expandable metallic stents (FCSEMSs) and plastic stents (PSs) were compared, and the risk factors for PEP, followed by PBD, were investigated for patients with pancreatic cancer.

Methods

Consecutive patients with pancreatic cancer who underwent PBD between April 2005 and March 2022 were included. We retrospectively evaluated recurrent biliary obstruction, adverse events (AEs), and postoperative complications for FCSEMS and PS groups and investigated the risk factors for PEP.

Results

A total of 105 patients were included. There were 20 patients in the FCSEMS group and 85 patients in the PS group. For the FCSEMS group, the rate of recurrent biliary obstruction (0% vs. 25%, p = 0.03) was significantly lower. There was no difference in AE between the two groups. No significant differences were observed in the overall postoperative complications, but the volume of intraoperative bleeding was larger for the PS group than it was for the FCSEMS group (p < 0.001). From multivariate analysis, being female and lack of main pancreatic duct dilation were independent risk factors for pancreatitis (odds ratio, 5.68; p = 0.028; odds ratio, 4.91; p = 0.048).

Conclusions

FCSEMSs are thought to be preferable to PSs for PBD due to their longer time to recurrent biliary obstruction. Being female and the lack of main pancreatic duct dilation were risk factors for PEP.

The usefulness of texture and color enhancement imaging to identify the minor papilla orifice

In clinical cases of pancreas divisum, endoscopic retrograde cholangiopancreatography often necessitates cannulation of the pancreatic duct through the minor papilla. Nevertheless, this procedure can be challenging because of the small size of the minor papilla and the difficulty in visualizing the ductal orifice. A new image-enhanced endoscopy technique called texture and color enhancement imaging (TXI) has been developed, which enhances texture, brightness, and color compared with white-light imaging, resulting in subtle differences in the surface mucosa. Herein, we describe the case of a 73-year-old man with pancreas divisum in whom TXI was useful in identifying the orifice of the minor papilla. He was referred to our hospital with repetitive acute exacerbation of chronic pancreatitis. Since contrast-enhanced computed tomography revealed a pancreatic stone in the main pancreatic duct, endoscopic retrograde cholangoepancreatography was performed as a therapeutic intervention. Despite the initial difficulty in identifying the orifice of the minor papilla on white-light imaging, TXI enhanced its visibility successfully, enabling dorsal pancreatic duct cannulation via the minor papilla. Subsequently, endoscopic pancreatic sphincterotomy was performed and a 6Fr plastic stent was placed. Post-endoscopic therapy, the patient's abdominal pain was relieved. TXI was useful in identifying the minor papilla orifice and led to successful cannulation.

Diagnostic value of homogenous delayed enhancement in contrast-enhanced computed tomography images and endoscopic ultrasound-guided tissue acquisition for patients with focal autoimmune pancreatitis

Background/Aims

We aimed to investigate (1) promising clinical findings for the recognition of focal type autoimmune pancreatitis (FAIP) and (2) the impact of endoscopic ultrasound (EUS)-guided tissue acquisition (EUS-TA) on the diagnosis of FAIP.

Methods

Twenty-three patients with FAIP were involved in this study, and 44 patients with resected pancreatic ductal adenocarcinoma (PDAC) were included in the control group.

Results

(1) Multivariate analysis revealed that homogeneous delayed enhancement on contrast-enhanced computed tomography was a significant factor indicative of FAIP compared to PDAC (90% vs. 7%, p=0.015). (2) For 13 of 17 FAIP patients (76.5%) who underwent EUS-TA, EUS-TA aided the diagnostic confirmation of AIPs, and only one patient (5.9%) was found to have AIP after surgery. On the other hand, of the six patients who did not undergo EUS-TA, three (50.0%) underwent surgery for pancreatic lesions.

Conclusions

Homogeneous delayed enhancement on contrast-enhanced computed tomography was the most useful clinical factor for discriminating FAIPs from PDACs. EUS-TA is mandatory for diagnostic confirmation of FAIP lesions and can contribute to a reduction in the rate of unnecessary surgery for patients with FAIP.

Treatment Strategy for Acute Cholecystitis Induced by a Metallic Stent Placed in Malignant Biliary Strictures: Role of Percutaneous Transhepatic Gallbladder Aspiration

Objective The present study evaluated the strategic role of percutaneous transhepatic gallbladder aspiration (PTGBA) for acute cholecystitis (AC) induced by a metallic stent (MS) placed in a malignant biliary stricture in comparison with percutaneous transhepatic gallbladder drainage (PTGBD). Methods The treatment outcomes for 31 patients who underwent PTGBA as the initial intervention for MS-induced AC were evaluated and compared with those for 12 who underwent PTGBD. Results The technical success rate was 100% for both groups. PTGBA was ineffective for 11 patients, all of whom recovered with additional intervention, whereas PTGBD was effective for all patients except for 1 who died of sepsis (clinical success rate, 65% vs. 90%, p=0.16). Adverse events (AEs) were observed in only 1 case (3%) in the PTGBA group (mild bile peritonitis). Among the clinically effective cases, AC recurred in 20% of the PTGBA group and 33% of the PTGBD group (p=0.72). In the PTGBA group, the clinical success rate was significantly higher for patients without cancer invasion to a feeding artery of the gallbladder than in those with invasion (75% without invasion vs. 29% with invasion; p=0.036). According to the multivariate analysis, this factor was an independent factor for clinical success of PTGBA (odds ratio, 9.27; p=0.040). Conclusion Although the clinical success rate of PTGBA for MS-induced AC was lower than that of PTGBD, PTGBA remains a viable option because of its safety and procedural simplicity, especially for cases without tumor invasion to a feeding artery.

Prospective feasibility study on the efficacy and safety of a novel spiral dilator for endoscopic ultrasound-guided drainage

Objectives

A difficult step in endoscopic ultrasound (EUS)‐guided drainage procedures is dilation of the puncture tract before stent deployment. The efficacy and safety of a novel spiral dilator, Tornus ES, for EUS‐guided drainage were investigated in this study.

Methods

This study was conducted as a prospective, single‐arm, observational study at Sendai City Medical center. Dilation of the puncture tract using a spiral dilator was attempted for all EUS‐guided drainage cases. The primary outcome was the technical success rate which was defined as successful stent placement in the puncture tract. Secondary outcomes were the success rate of dilation using a spiral dilator, procedure time, and adverse events related to the procedures.

Results

A total of 10 patients were enrolled between January and March 2022. Seven patients underwent EUS‐guided biliary drainage (hepaticogastrostomy for six and hepaticojejunostomy for one), and the remaining three patients underwent EUS‐guided gallbladder drainage. The technical success rate and the success rate of dilation using a spiral dilator were both 100%. The mean procedure time was 27 min. No adverse events related to the procedure occurred in all cases.

Conclusions

Dilation of the puncture tract using a spiral dilator was effective and safe and might make it easier to perform EUS‐guided drainage.

Safety of Cold Snare Polypectomy in Patients Receiving Treatment with Antithrombotic Agents

BACKGROUND

With the aging of the population and rising incidence of thromboembolic events, the clinical use of antithrombotic agents is also increasing. There are few reports yet on the management of antithrombotic agent use in patients undergoing cold snare polypectomy (CSP).

AIMS

The aim of this study was to evaluate whether continued administration of antithrombotic agents in patients undergoing CSP would be associated with an increased rate of delayed post-polypectomy bleeding (DPPB).

METHODS

A total of 1177 colorectal polyps in 501 patients were resected at Omori Red Cross Hospital between October 2017 and March 2018. The polyps were divided into two groups depending on whether the patients received antithrombotic agent treatment or not: the antithrombotic group (911 polyps) and the no-antithrombotic group (266 polyps).

RESULTS

Among the 1177 polyp resections, there was no case of DPPB, including in the antithrombotic group. Immediate bleeding occurred in a total of 63 (5.4%) cases. Polyp location in the rectum (OR (95% CI) 2.64 (1.223-5.679); p = 0.013), polyp size ≥ 6 mm (OR (95% CI) 4.64 (2.719-7.933); p < 0.001), polypoid growth pattern (OR (95% CI) 2.78 (1.607-4.793); p < 0.001), and antithrombotic agent use (OR (95% CI) 2.98 (1.715-5.183); p < 0.001) were identified as significant risk factors of immediate bleeding.

CONCLUSIONS

Continued use of antithrombotic agents does not increase the risk of DPPB, even in those receiving multiple antithrombotic agents. Thus, it is safe to perform CSP even in multiple agent users. Prospective, randomized studies are necessary to confirm our results.

PTHrP Induces Notch Signaling in Periodontal Ligament Cells

Periodontal ligament (PDL) cells are known to play important roles in tooth eruption and alveolar bone metabolism. We previously reported that PTHrP increases RANKL expression in human PDL cells, suggesting that it promotes odontoclastic root resorption during tooth eruption. While it is known that Notch-related genes play a key role during bone development, the role of the Notch signaling pathway in PDL cells during tooth and bone resorption is less clear. We hypothesized that PTHrP induces a Notch ligand in PDL cells and thereby regulates osteo- and odontoclastogenesis. We found that PTHrP increased Notch1 ligand Jagged1 expression in human PDL cells in a dose- and time-dependent manner. PTHrP-induced Jagged1 up-regulation was mediated by PKA activation, but not by PKC. Jagged1 also promoted RANKL-induced osteoclastogenesis. These results demonstrate that PTHrP induces Jagged1 expression in PDL cells, leading to osteo- and odontoclastogenesis, and thus likely promoting tooth and alveolar bone resorption.

Susceptibility of type 2 diabetic mice to low-virulence bacterial infection: induction of abscess formation by gingipain-deficient Porphyromonas gingivalis

BACKGROUND AND OBJECTIVE

Type 2 diabetes mellitus is considered an important risk factor of adult periodontitis. However, recent studies have revealed that the subgingival microbial flora of diabetes mellitus patients does not differ from that of healthy individuals. In this study, we examined the response of type 2 diabetes mellitus hosts to low-virulence bacteria in a murine abscess model.

MATERIAL AND METHODS

Porphyromonas gingivalis ATCC 33277 or KDP128 (rgpA rgpB kgp) were injected into two mouse strains - C57BL/6J and its derivative, KK/A(Y), which becomes diabetic spontaneously.

RESULTS

Lesions of KK/A(Y) mice injected with either low-virulence P. gingivalis KDP128 or wild-type 33277 were significantly larger than those of C57BL/6J mice injected with the same strains. Histologically, more neutrophils and macrophages migrated to the lesions in the KK/A(Y) mice injected with P. gingivalis 33277 and KDP128 compared with those of C57BL/6J mice injected with the same respective strains.

CONCLUSION

These results suggest that severe inflammation is observed in response to low-virulence bacteria in addition to the highly virulent bacteria in type 2 diabetes mellitus hosts.

Mixed infection of Porphyromonas gingivalis and Bacteroides forsythus in a murine abscess model: involvement of gingipains in a synergistic effect

Several microorganisms including Porphyromonas gingivalis and Bacteroides forsythus have been implicated to be etiologically important agents of periodontal disease. In this study, we determined the ability of combinations of periodontopathogenic microorganisms to cause tissue destruction in a murine abscess model. Although all bacterial combinations used in this study produced larger abscesses than did monoinfection of each bacterium, the combination of P. gingivalis and B.forsythus showed a synergistic effect on abscess formation. Since these two bacteria have been frequently found together in lesions of periodontitis, these results suggest the significance of their co-infection in the progression of periodontitis. P. gingivalis produces extracellular and cell-associated cysteine proteinases (gingipains) which appear to be involved in its virulence. The rgpA rgpB double and kgp mutants induced significantly smaller abscesses than the wild type. Moreover, the rgpA rgpB kgp triple (gingipain-null) mutant hardly showed lesion formation at all with the experimental conditions used in this study, indicating that these genes encoding gingipains are important for virulence of P. gingivalis. Mixed infection of these P. gingivalis mutants with B. forsythus showed an additive effect on abscess formation, indicating that the gingipains of P. gingivalis may play an important role in the pathological synergism between P. gingivalis and B. forsythus.

Intracystic papillary carcinoma in the male breast. A case report

Male breast cancer is a rare disease with an incidence between 0.5% and 2.4% of that in women. We report a case of intracystic papillary carcinoma of the breast in a 75-year-old Japanese man. The macroscopic features of the carcinoma could be accurately demonstrated by pneumocystography and ultrasonography preoperatively.

Development of mineralized nodules in fetal rat mandibular osteogenic precursor cells: requirement for dexamethasone but not for beta-glycerophosphate

We have reported that a cell population obtained from fetal rat mandible with neutral protease (Pro I) has a unique differentiation sequence in which the elevation of alkaline phosphatase (ALPase), calcium accumulation, and collagen synthesis occurs simultaneously. In this report, we further characterized Pro I-released population of cells by studying the effect of dexamethasone (Dex) or beta-glycerophosphate (beta-GP) on the formation of bone nodules. The formation of bone nodules in Pro I-released population of cells (ProIRPC) was augmented by the addition of Dex (10(-7) M) from days 3 to 14, suggesting that Pro IRPC contained osteoprogenitor (OP) cells. A 24-hour pulse treatment of ProIRPC released population of cells with Dex on days 9 and 12 resulted in an increase in the number of nodules but treatment on days 3, 6, or 15 did not. The number of bone nodules formed in Pro IRPC pulse treated with Dex on day 9 was comparable with that in Pro IRPC treated with Dex from days 3 to 14. Dex caused an earlier elevation of ALPase, in which maximal expression was observed on day 10. beta-GP caused a prolonged elevation of ALPase, but did not affect the formation of bone nodules. Unlike Pro I-released population of cells, rat calvarial cells did not form mineralized nodules without beta-GP, and showed that a Dex-responsive period on bone nodule formation in rat calvarial cells was at preconfluency (days 0 and 1). Thus, it appeared that the Dex-induced differentiation of early OP cells in Pro IRPCs occurred during the limited period from day 9 to day 12. Pro IRPC was found to have an unique characteristic that bone nodule formation was not affected by beta-GP.

Peptide based interleukin-1 beta converting enzyme (ICE) inhibitors: synthesis, structure activity relationships and crystallographic study of the ICE-inhibitor complex

Based on the X-ray structure of the complex of Ac-Tyr-Val-Ala-Asp-H (L-709049) and interleukin-1 beta converting enzyme (ICE), we synthesized compounds which were derived from 2-NapCO-Val-Pro-Asp-CH2OPh (1) to obtain a potent inhibitor in the cell assay. Among these compounds, (3S)-N-methanesulfonyl-3-[[1-[N-(2-naphthoyl)-L-valyl]-L-prolyl]amino]- 4-oxobutanamide (27c) showed high potency not only in the enzyme assay but also cell assay with IC50 values of 38 nM and 0.23 microM, respectively. Compound 27c, with a c log P value of 1.76, had a more hydrophilic character compared with 1. Compound 27c also dose dependently inhibited LPS-primed ATP-induced IL-1 beta release in mice. The crystal structure of the complex of compound 27c and ICE revealed that compound 27c had further interactions with ICE in the naphthoyl group at the P4 position and in the methyl group of the methanesulfonamidecarbonyl group at the P1 position, compared with L-709049. To our knowledge, compound 27c is the first example that shows a strong inhibitory activity without the carboxyl group at the P1 position.

An immunohistochemical study of the behavior of cells expressing interleukin-1 alpha and interleukin-1 beta within experimentally induced periapical lesions in rats

Cells expressing interleukin-1 (IL-1) were examined in rat periapical lesions using immunohistochemical methods. During the acute phase, both IL-1 alpha- and IL-1 beta-expressing cells were observed adjacent to many osteoclasts that contained large cytoplasms, and consequently the periapical lesions tended to expand. However, the number of IL-1 beta-expressing cells was about twice that of IL-1 alpha-expressing cells during the same period. On the other hand, there were significantly less IL-1 beta-expressing cells during the chronic phase and consequently a significant expansion of the periapical lesions was not seen. Furthermore, IL-1 alpha- and IL-1 beta-expressing cells were located far from the bone surfaces, whereas a fibroblastic cell layer lay between the IL-1-expressing cells and the bone surfaces. Both IL-1 alpha and IL-1 beta were mainly expressed by macrophages. In addition, after the percolated application of formocresol to experimentally induced periapical lesions, numerous macrophages expressing IL-1 beta became conspicuous within the vicinity of the extensive bone resorption sites. These results suggest that macrophages expressing IL-1 beta may play an important role in the activation and recrudescence of osteoclastic bone resorption, and this may be due to their localization close to the bone resorption sites noted within experimental periapical lesions.

[An epidemiologic examination on the prevalence of the periodontal diseases and oral pigmentation in Yusho patients in 1996]

An epidemiologic examination was carried out to reveal the prevalence of the periodontal diseases and oral pigmentation in patients with Yusho 28 years after PCB exposure. The results obtained were as follows. 1) 162 teeth out of a total of 309 examined teeth had a periodontal pocket deeper than 3 mm, although 32 teeth out of 162 teeth had a periodontal pocket deeper than 4 mm. 2) Oral pigmentation was observed in 47 out of 82 patients with Yusho. It was particularly noteworthy that gingival pigmentation was observed at a much higher frequency in younger patients while pigmentation of the buccal mucosa, the lips or the palate was observed at a much higher frequency in older patients.

In vitro interaction between tetracalcium phosphate-based cement and calvarial osteogenic cells

Newly-developed tetracalcium phosphate-based cement (4CP cement) and cells derived from neonatal rat calvaria were cocultured to study the in vitro reaction of osteoblastic cells to the biomaterial at light and electron microscopic levels. Three-dimensional nodular structures covered with active osteoblastic cells were formed in the periphery of the test material and they contained a mineralized tissue that exhibited features closely resembling bone formed in vivo. Ultrastructurally, the test material was circumscribed with an electron-dense structure, and was immediately adjacent to elongated cyoplasmic processes with intact morphology or collagen fibrils with periodic structures. Furthermore, the mineralization of the extracellular collagenous matrix occurred directly on the surface of the material. These in vitro findings suggest the ability of 4CP cement to bind directly with newly-formed hard tissues.

Effects of a combination of an antibacterial agent (ofloxacin) and a collagenase inhibitor (FN-439) on the healing of rat periapical lesions

To investigate the effects of a combination of an antibacterial agent (ofloxacin) and a collagenase inhibitor (FN-439) in the root canal treatment of apical periodontitis, we studied the healing process of experimentally induced periapical lesions in rats by using immunohistochemical methods. With a topical application of a combination of ofloxacin and FN-439 following experimentally induced periapical lesions, both neutrophils and macrophages became significantly decreased in number, while active cementogenesis and extensive bone formation were seen in the periapical region. However, the use of ofloxacin alone also demonstrated a beneficial effect on periapical inflammation and healing. Therefore, it is suggested that ofloxacin is powerful against bacterial infection whether FN-439 is added. The only observed effect of a combination of ofloxacin and FN-439 is that it may more effectively inhibit osteoclastic bone resorption and activate the remodeling of the apical periodontal tissue if this combined medicament is used in a stage of active bone destruction characterized by high production of tissue collagenase.

4-(3,4-Dihydroxyphenyl)-1,2,3,4-tetrahydroisoquinoline derivatives. II. Their renal vasodilation activity and structure-activity relationship

A series of 4-(3,4-dihydroxyphenyl)-1,2,3,4-tetrahydroisoquinoline derivatives showed potent DA1 agonistic activities. We investigated the structure-activity relationship of the racemic compounds of this series. 4-(3,4-Dihydroxyphenyl)-7-methanesulfonamido-1,2,3,4-tetrahydroiso quinoline (43) was identified as a potent renal vasodilator with activity almost equal to that of YM435 (1).

[An epidemiologic examination on the prevalence of the periodontal diseases and oral pigmentation in Yusho patients]

An epidemiologic examination was carried out to reveal the prevalence of the periodontal diseases and oral pigmentation in Yusho patients 26 years after PCB exposure. The results obtained were as follows. 1) 158 teeth of the total 284 examined teeth had the periodontal pockets deeper than 3 mm and the lower left first molar showed the highest prevalence of the periodontal pocket among the examined six index teeth. There was no definitive difference not only between sexes but also between age groups. However, 42 teeth had the periodontal pockets deeper than 4 mm. 2) Oral pigmentation was observed in 25 Yusho patients (33.8%). Chronological examination revealed that the prevalence of oral pigmentation seemed to be higher in the patients below the age of 49 than in those beyond the age of 50, but there was no definitive difference between sexes. It was of particular interest that the incidence of oral pigmentation appeared to decrease with decrease of the teeth present in number.

Detection of interleukin-1 beta mRNA in rat periapical lesions

Cells expressing interleukin-1 beta (IL-1 beta) mRNA were demonstrated by in situ hybridization in rat periapical lesions. A great number of osteoclasts with significant tartrate-resistant acid phosphatase activity were observed on the bone surfaces, and numerous IL-1 beta mRNA-expressing cells were widely distributed in the periodontal ligaments. IL-1 beta mRNA-expressing cells were mainly observed around the blood vessels in the vicinity of the bone resorption sites and occasionally found near the osteoblasts. Immunohistochemistry and enzyme histochemistry assays showed that IL-1 beta mRNA-expressing cells were not bone cells, but that they had the characteristic features of macrophages. These results suggested that macrophages may contribute to the production of IL-1 beta and play an important role in activation of osteoclastic bone resorption.

A histochemical study of the behavior of macrophages during experimental apical periodontitis in rats

The behavior of macrophages from experimentally induced periapical lesions of rats was studied in paraffin sections using nonspecific esterase and a monoclonal antibody, ED1. Macrophages were seen near the regularly arranged osteoblasts in controls and the detached osteoblasts at the initiation phase of bone resorption. In addition, numerous macrophages were widely distributed throughout the periodontium at the activation phase of bone resorption. On the other hand, macrophages were rarely seen near the bone formation surfaces, but large numbers of macrophages were localized in microabscess at the activation phase of bone formation. It is suggested that macrophages may play an important role in activation of osteoclastic bone resorption and inhibition of complete bone repair in bone remodeling during experimental apical periodontitis.

An enzyme histochemical study of the behavior of rat bone cells during experimental apical periodontitis

Bone alkaline and tartrate-resistant acid phosphatase activities were studied in paraffin sections obtained from experimentally induced periapical lesions of rats. These enzyme activities were demonstrated despite the use of high temperatures during embedding. In the formation phase, numerous osteoblasts and periodontal ligament cells showed strong alkaline phosphatase activity. On the other hand, a number of osteoclasts and preosteoclasts showed tartrate-resistant acid phosphatase activity in the activated resorption sites of periapical lesions. It is suggested that enzyme histochemical applications to paraffin sections are a useful means for clarifying the behavior of bone cells and that bone remodeling has occurred in the periapical lesions.

Rosette formation of impacted molar teeth in mucopolysaccharidoses and related disorders

The radiographic features of the jaws in the mucopolysaccharidoses and related disorders (MPS) have been reviewed and three further cases are reported here, with particular reference to a novel dental anomaly, not previously described in detail, in two of them. The dental changes appear to be fully developed by the third decade and are characterized by bilateral multiple impacted molar teeth, which conglomerate in a single follicle to form a characteristic rosette of teeth. Rosetting was present only in relatively mature cases of MPS. However, it was also seen in the fourth patient, where we could not detect any other abnormal clinical or radiographic features. We therefore propose that since multiple rosetting of molar teeth can also occur in an isolated form, it is only suggestive of MPS.

Synthesis, resolution, and renal vasodilation activity of novel DA1 agonists: 4-(3,4-dihydroxyphenyl)-1,2,3,4-tetrahydroisoquinoline derivatives

7,8-Dihydroxy-4-(3,4-dihydroxyphenyl)-1,2,3,4-tetrahydroisoquinoline (1) and 4-(3,4-dihydroxyphenyl)-7-hydroxy-8-methyl-1,2,3, 4-tetrahydroisoquinoline (2) are potent renal vasodilators which selectively stimulate DA1 (peripheral dopamine receptor-1) receptors. Especially, (S)-(-)-1 is the most potent. Its DA1 agonist activity is about 10 times stronger than dopamine for increasing renal blood flow in anesthetized dogs. The renal and cardiovascular effects of (S)-(-)-1 may be suitable for the treatment of patients with renal insufficiency, heart failure and hypertension.

A histochemical study of bone remodeling during experimental apical periodontitis in rats

An apical periodontitis experimental model was produced by means of opening the pulp chamber of the mandibular first molar in Wistar strain rats. In particular, the behavior of bone tissue in the vicinity of the root apex was investigated histochemically, ultrastructurally, and quantitatively. In addition, in order to demonstrate the effects of prostaglandin on the formation process of apical periodontitis, we examined the effects of indomethacin on bone remodeling during experimental apical periodontitis. These experiments suggested that prostaglandin may stimulate osteoclastic bone resorption and that the relationship between bone resorption and formation in apical periodontitis is a coupling phenomenon.

[Immunohistological and histopathological study of the effect of PCB on the periodontal tissue]

We performed immunohistochemical and histopathological investigation on the inflamed gingiva from the patient with Yusho and on the periodontal tissue from PCB poisoned rats respectively. The results obtained were as follows. 1) In the gingiva from the Yusho patients, the proportions of plasma cells, B cells, T cells in the inflammatory cells and CD4/CD8 ratio were 47.9%, 18.3%, 10.7%, and 2.84, respectively. 2) In the periodontal tissue from rats with experimental periodontitis, we found no definitive difference between the PCB poisoned rats and the clinically healthy rats.