The potential of a surface pre-reacted glass root canal dressing for treating apical periodontitis in rats.

AIM: To evaluate the efficacy of a prototype root canal dressing containing surface pre-reacted glass-ionomer (S-PRG) fillers on repairing induced periapical lesions in a rat model. Calcium hydroxide [Ca(OH)2 ] was applied as a comparison in the healing process. METHODOLOGY: The pulp chambers of the maxillary first molars in 64 male Wistar rats aged 16 weeks were opened to induce periapical lesions. After 28 days, the mesial canal of each tooth was prepared, irrigated with 2.5% sodium hypochlorite only (control group: irrigation) or followed by the respective dressing [Ca(OH)2 group, irrigation + Ca(OH)2 ; S-PRG group, irrigation + S-PRG] and restored with composite resin for 3 or 7 days (10/group). Four rats with healthy molars were used as blank controls. Descriptive analysis of the periapical radiographs, haematoxylin and eosin staining and immunohistochemical observation was performed 3 and 7 days after treatment. The periapical grey value, CD68 macrophages and osteoclasts (cathepsin-K) were quantified and statistically analysed with Tukey's honest significant difference test. A significant difference was achieved when P values were <0.05. RESULTS: S-PRG and Ca(OH)2 dressings were associated with increased periapical grey values and inhibited osteoclast activity at 3 and 7 days; a significant difference in radiographic results and the number of osteoclasts was obtained at 3 and 7 days compared with the control group (P < 0.05). Reparative tissue was observed histologically in the space of the periapical resorbed necrotic area after S-PRG and Ca(OH)2 treatment for 3 and 7 days. The number of macrophages was significantly decreased at 3 and 7 days in the S-PRG and Ca(OH)2 specimens when compared with the controls (P < 0.05). CONCLUSIONS: In a rat experimental model, the S-PRG root canal dressing was comparable to Ca(OH)2 in promoting the healing of experimentally induced periapical lesions. S-PRG paste has the potential to be used as an alternative intracanal dressing in teeth with apical periodontitis.

Correlation of mandibular impacted tooth and bone morphology determined by cone beam computed topography on a premise of third molar operation.

PURPOSE: To determine the width and morphology of the mandible in the impacted third molar region, and to identify the location of the mandibular canal prior to planning impacted third molar operations. METHODS: Cone beam computed tomography (CBCT) data of 87 mandibular third molars from 62 Japanese patients were analyzed in this study. The width of the lingual cortical bone and apex-canal distance were measured from cross-sectional images in which the cortical bone was thinnest at the lingual side in the third molar region. Images were used for measuring the space (distance between the inner border of the lingual cortical bone and outer surface of the third molar root), apex-canal distance (distance from the root of the third molar tooth to the superior border of the inferior alveolar canal) and the cortical bone (width between the inner and outer borders of the lingual cortical bone). RESULTS: The means of the space, apex-canal distance and lingual cortical width were 0.31, 1.99, and 0.68 mm, respectively. Impacted third molar teeth (types A-C) were observed at the following frequencies: type A (angular) 37 %; type B (horizontal), 42 %; type C (vertical), 21 %. The morphology of the mandible at the third molar region (types D-F) was observed as: type D (round), 49 %; type E (lingual extended), 18 %; and type F (lingual concave), 32 %. CONCLUSIONS: The width and morphology of the mandible with impacted teeth and the location of the mandibular canal at the third molar region could be clearly determined using cross-sectional CBCT images.

Salivary microbial levels in relation to periodontal status and caries development.

BACKGROUND AND OBJECTIVE: Although an inverse relationship between caries and periodontal disease has been suggested, some studies have reported a positive correlation between periodontal disease and the decayed, missing and filled teeth (DMF) index. The aim of the present study was to examine the relationship between caries and periodontal disease. MATERIAL AND METHODS: We assessed the clinical parameters and salivary levels of Porphyromonas gingivalis and Streptococcus mutans using real-time polymerase chain reaction in 40 subjects with varying degrees of caries and periodontal disease. RESULTS: The salivary levels of S. mutans were significantly higher in the periodontally healthy group than in the periodontitis group. The salivary levels of P. gingivalis were significantly higher in the caries-free group than in the periodontally healthy group with caries. The salivary levels of S. mutans were significantly increased after the initial periodontal treatment. CONCLUSIONS: This study showed that an inverse relationship exists between periodontitis and caries in terms of the clinical and bacteriological findings.

Comparison of the effects of polysulfone and polyester-polymer alloy dialyzers on glycemic control in diabetic patients undergoing hemodialysis.

BACKGROUND: Though different high-flux dialyzers are available, there are no comparative studies on their glycemic control effects on diabetic hemodialysis (HD) patients. In this crossover study, we compared the effects of polysulfone (PS) and polyester-polymer alloy (PEPA) dialyzers. METHODS: We recruited 47 diabetic HD patients. The conventional dialyzers were replaced with PS or PEPA dialyzers and the patients were treated for 16 weeks. Subsequently, after interchanging the PS and PEPA dialyzers, the treatment continued for another 16 weeks. For each dialyzer, we analyzed the glycemic control effect and measured their clearance and reduction rates of insulin. RESULTS: The PEPA dialyzer lowered the glycated albumin (GA) levels more significantly than the PS dialyzer. While the groups exhibited no differences in metabolic parameters, the clearance and reduction rates of insulin were more significant in the PS. A significant decrease was observed in the levels of GA, fasting plasma glucose, and glycated hemoglobin in patients with lower fasting C-peptide levels (< 6.0 ng/ml). CONCLUSION: Glycemic control in diabetic HD patients is affected by the type of dialyzer used. Our results indicate that the PEPA dialyzer is more potent in controlling glycemia than the PS dialyzer in diabetic HD patients.

Periodontitis Is Associated with Chronic Obstructive Pulmonary Disease.

Although they are known to share pathophysiological processes, the relationship between periodontitis and chronic obstructive pulmonary disease (COPD) is not fully understood. The aim of the present study was to test the hypothesis that periodontitis is associated with a greater risk of development of COPD, when smoking is taken into account. The analysis in a 5-y follow-up population-based cohort study was based on 900 community-dwelling Japanese adults (age: 68.8 ± 6.3 [mean ± SD], 46.0% male) without COPD aged 60 or older with at least 1 tooth. Participants were classified into 3 categories according to baseline periodontitis severity (no/mild, moderate, and severe). COPD was spirometrically determined by a fixed ratio of <0.7 for forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) and by FEV1/FVC below the lower limit of normal. Poisson regression was used to calculate the relative risk (RR) of developing COPD according to the severity of periodontitis. The population attributable fraction (PAF) was also calculated. During follow-up, 22 (2.4%) subjects developed COPD. Compared with no/mild periodontitis subjects, a significantly increased risk of COPD occurred among severe periodontitis subjects (RR = 3.55; 95% confidence interval [CI], 1.18 to 10.67), but no significant differences were observed between the no/mild and moderate categories (RR = 1.48; 95% CI, 0.56 to 3.90). After adjustment for potential confounders, including smoking intensity, the relationship between severe periodontitis and risk of COPD remained significant (RR = 3.51; 95% CI, 1.15 to 10.74). Likewise, there was a positive association of periodontitis severity with risk of COPD ( P for trend = 0.043). The PAF for COPD due to periodontitis was 22.6%. These data highlight the potential importance of periodontitis as a risk factor for COPD.

The influence of hemodialysis membranes on the plasma insulin level of diabetic patients on maintenance hemodialysis.

AIM: The aim of the present study was to evaluate the alteration in plasma immunoreactive insulin (IRI) concentrations due to hemodialysis (HD) treatment by using three types of membranes in diabetic HD patients. METHOD: We recruited 20 outpatients on maintenance HD with diabetes for this crossover study. HD was performed using membranes made of cellulose triacetate (CTA), polyester-polymer alloy (PEPA), and polysulphone (PS). These membranes were used for 2 weeks (6 HD sessions) in each patient in a randomized order decided by drawing lots. Blood samples were obtained at the beginning and end of the HD session from the blood tubing at the arterial (A) site. At 60 min after the initiation of dialysis, blood samples were obtained from the blood tubing at both the A and venous (V) sites of the dialyzer. RESULTS: The plasma IRI levels decreased significantly at the sites an hour after initiating HD in all membranes. The clearance of IRI was significantly higher in the case of the PS membrane when compared with the CTA and PEPA membranes. CONCLUSIONS: It was concluded that plasma insulin is cleared by HD, and the rate differs for each membrane. Plasma insulin clearance with the PS membrane is higher than that with the PEPA and CTA membranes.

Hepatic differentiation of mouse embryonic stem cells in a bioreactor using polyurethane/spheroid culture.

BACKGROUND: We have previously developed a hybrid artificial liver (HAL) using polyurethane foam (PUF)/hepatocyte spheroid culture. The PUF-HAL has been successfully scaled up to a clinical level. However, one of the most difficult problems for clinical application of HALs is obtaining a cell source. We now focused our attention on embryonic stem (ES) cells as a potential source for HAL. In this study, we investigated the differentiation of mouse ES (mES) cells into functional hepatocytes in the PUF-HAL module. METHODS: The PUF-HAL module included a cylindrical PUF block having many capillaries for medium flow. mES cells were immobilized in the module. To induce hepatic differentiation, growth factors were added to the culture medium. We evaluated cell density, gene expression analysis, and liver-specific functions. RESULTS: mES cells spontaneously formed spherical multicellular aggregates (spheroids) in the pores of PUF. mES cells proliferated by 20 days, achieving a high cell density (about 1 x 10(8) cells/cm3 PUF). Differentiating ES cells expressed endodermal-specific genes such as alpha-fetoprotein, albumin, and tryptophan 2, 3-deoxygenase. The activity of ammonia removal of mES cells per unit volume of the module was detectable by 15 days and increased with culture time. Maximal expression levels were comparable to those of primary (porcine and human) hepatocytes. SUMMARY: mES cells immobilized in the PUF module expressed liver-specific functions at high level, because of high cell density in culture and hepatic differentiation. These results indicated that PUF module-immobilized mES cells may be useful as a biocomponent of HALs.

Clinical evaluation of plasma insulin and C-peptide levels with 3 different high-flux dialyzers in diabetic patients on hemodialysis.

AIM: Changes in plasma immunoreactive insulin (IRI) and connecting-peptide immunoreactivity (CPR) concentrations during hemodialysis (HD) were evaluated in diabetic HD patients with 3 different high-flux membranes. The removal properties of the membranes were compared. METHOD: In this prospective controlled study, 15 stable diabetic patients on HD were randomly selected for 6 HD sessions with 3 different membranes: polysulfone (PS), cellulose triacetate (CTA), and polymethylmethacrylate (PMMA). Blood samples were obtained from the blood tubing at the arterial (A) site at the beginning and end of the sixth HD session. At 60 minutes after dialysis initiation, blood samples were obtained from both the A and venous (V) sites of the dialyzer to investigate the clearance and removal properties of the membranes. RESULTS: The plasma IRI and CPR levels decreased significantly at each time point with all 3 membranes. IRI clearance with the PS membrane was significantly higher than that with the CTA and PMMA membranes. No difference was observed in the IRI reduction rate between the 3 membranes. CPR clearance and reduction rate with the PMMA membrane were lower than with the PS and CTA membranes. No significant difference was observed in serum creatinine clearance and reduction rates between the 3 membranes; however, serum urea nitrogen clearance was significantly lower with the PMMA membrane compared with the PS and CTA membranes. A significantly high beta2-microglobulin clearance and reduction rate was achieved in the order PS > CTA > PMMA. CONCLUSION: Plasma IRI and CPR are cleared by HD; their clearance rates differ with the dialyzer membranes. Plasma IRI clearance with the PS membrane is higher than that with the CTA and PMMA membranes.

Is the removal of osteosynthesis plates after orthognathic surgery necessary? Retrospective long-term follow-up study.

The removal of titanium miniplates is a controversial topic in oral and maxillofacial surgery. This retrospective study examined the timing of and reasons for titanium plate removal after orthognathic surgery. The study included 240 orthognathic surgery patients (71 male, 169 female; age range 16-55 years, mean 25.0±8.8 years) who had maxillofacial osteosynthesis plates inserted or inserted and then removed at the Division of Oral and Maxillofacial Surgery, Kagawa Prefectural Central Hospital, between April 2003 and March 2017. During the study period, a total of 717 miniplates were inserted in the 240 patients, and 71 of the patients (29.6%) had 236 plates (32.9%) removed. Ten patients (14.1%) had their plates removed within a year due to early complications. Although no patient had their plate removed due to complications at 1-5 years postoperative, a further 14 patients (19.7%) had their plates removed after more than 5 years of long-term follow-up due to plate-related complications. Complications requiring plate removal were evidently biphasic, occurring within 1 year after the operation and at ≥5 years after the operation. Therefore, after confirming postoperative bone healing, it is necessary to explain to patients the risks of plate removal and the importance of long-term follow-up.

Hepatocyte growth factor ameliorates acute graft-versus-host disease and promotes hematopoietic function.

Acute graft-versus-host disease (GVHD) is a major complication of bone marrow transplantation (BMT) and is characterized by hematopoietic dysfunction, immunosuppression, and tissue injury in the skin, liver, and intestinal mucosa. Hepatocyte growth factor (HGF), originally identified and cloned as a potent mitogen for hepatocytes, induces mitogenic and antiapoptotic activity in various epithelial cells and promotes hematopoiesis. Working in a murine model of acute GVHD, we performed repeated transfection of the human HGF cDNA into skeletal muscle and showed that this treatment inhibited apoptosis of intestinal epithelial cells and donor T-cell infiltration into the liver, thereby ameliorating the enteropathy and liver injury caused by acute GVHD. HGF also markedly suppressed IFN-gamma and TNF-alpha expression in the intestine and liver and decreased the serum IL-12. Furthermore, extramedullary hematopoiesis by donor cells was increased, and the survival rate was improved. These results suggest that HGF may be useful for controlling acute GVHD after allogeneic BMT.

Branched-chain amino acids supplementation attenuates the accumulation of blood lactate dehydrogenase during distance running.

AIM: We investigated the effect of branched-chain amino acids (BCAA) supplementation on tissue damage during distance running. METHODS: Eight male distance runners (mean +/- standard deviation; age: 20.4+/-1.2 years, body weight: 58.4+/-4.2 kg) participated in a double blinded cross over designed study conducted during training camp. During each intervention period, the subjects were asked to participate in a 25-km run, and the blood BCAA and lactate dehydrogenase (LDH) level, an index of tissue damage, were measured pre- and post-run. Either a drink containing BCAA (0.4% BCAA in a 4% carbohydrate solution) or an iso-calorie placebo drink was provided to the subjects 5 times during the run without any restriction in the volume. RESULTS: The total volume of the drink consumed by the subjects did not differ substantially between the trials: 591+/-188 (2.36 g BCAA) vs 516+/-169 mL in BCAA and placebo trial, respectively. During the run, the blood BCAA concentration was maintained in the BCAA trial. However, the blood BCAA concentration level tended to decrease in the placebo trial (P<0.1). The extent of the blood LDH increase in the BCAA trial was significantly less than that of the placebo trail (48% vs 58%, P<0.05). CONCLUSION: Maintaining the blood BCAA level throughout a long distance run contributes to a reduction in the LDH release and, therefore, the effect of BCAA supplementation is suggested to reduce the degree of muscle damage.

Enhanced suppression of tumor growth using a combination of NK4 plasmid DNA-PEG engrafted cationized dextran complex and ultrasound irradiation.

This investigation aims to determine experimentally whether or not ultrasound (US) irradiation is effective in enhancing the in vivo gene expression of NK4 plasmid DNA and suppressing tumor growth. NK4, composed of the NH2-terminal hairpin and subsequent four-kringle domains of hepatocyte growth factor (HGF), acts as an HGF-antagonist and angiogenesis inhibitor. Dextran was cationized by introducing spermine to the hydroxyl groups to allow for polyionic complexation with NK4 plasmid DNA. The cationized dextran was additionally modified with poly(ethylene glycol) (PEG) molecules giving PEG engrafted cationized dextran. Significant suppression of tumor growth was observed when PEG engrafted cationized dextran-NK4 plasmid DNA complexes were intravenously injected into mice carrying a subcutaneous Lewis lung carcinoma tumor mass with subsequent US irradiation when compared with the cationized dextran-NK4 plasmid DNA complex and naked NK4 plasmid DNA with or without US irradiation. We conclude that complexation with PEG-engrafted cationized dextran in combination with US irradiation is a promising way to target the NK4 plasmid DNA to the tumor for gene expression.

First molecular detection of R. conorii, R. aeschlimannii, and R. massiliae in ticks from Algeria.

Ticks collected in Northern Algeria between May 2001 and November 2003 were tested by PCR for the presence of Rickettsia spp. DNA using primer amplifying gltA and OmpA genes. Three different spotted fever group rickettsias were amplified from these ticks: R. Conorii subsp. P. conorii strain Malish in Rhipicephalus sanguineus, R. aeschlimannii in Hyalomma marginatum, and R. massiliae in Rhipicephalus turanicus. Our results confirm the presence of R. conorii in ticks in Algeria and provide the first detection of R. aeschlimannii and R. massiliae in Algeria.

Therapeutic angiogenesis induced by human hepatocyte growth factor gene in rat diabetic hind limb ischemia model: molecular mechanisms of delayed angiogenesis in diabetes.

BACKGROUND: Because no study has documented the angiogenic properties of hepatocyte growth factor (HGF) in a diabetes model, we examined the feasibility of gene therapy using HGF to treat peripheral arterial disease in diabetes. METHODS AND RESULTS: Because intramuscular injection of luciferase plasmid by the hemagglutinating virus of Japan (HVJ)-liposome method had much higher efficiency than injection of naked plasmid, we used the HVJ-liposome method to transfect the human HGF gene into the rat diabetic hindlimb model. As expected, transfection of human HGF vector resulted in a significant increase in blood flow as assessed by laser Doppler imaging and capillary density, even in the diabetes model, accompanied by the detection of human HGF protein. Interestingly, the degree of natural recovery of blood flow was significantly greater in nondiabetic rats than in diabetic rats. Thus, in an in vitro culture system, we further studied the molecular mechanisms of how diabetes delayed angiogenesis. Importantly, high-D-glucose treatment of endothelial cells resulted in a significant decrease in matrix metalloproteinase (MMP)-1 protein and ets-1 expression in human aortic endothelial cells. Similarly, high D-glucose significantly decreased mRNA and protein of HGF in endothelial cells. Downregulation of MMP-1 and ets-1 by high D-glucose might be due to a significant decrease in HGF, because HGF stimulated MMP-1 production and activated ets-1. CONCLUSIONS: Overall, intramuscular injection of human HGF plasmid induced therapeutic angiogenesis in a rat diabetic ischemic hindlimb model as a potential therapy for peripheral arterial disease. The delay of angiogenesis in diabetes might be due to downregulation of MMP-1 and ets-1 through a decrease in HGF by high D-glucose.

Mechanism of the immunosuppressive effect in vivo of novel immunosuppressive drug beta-SQAG9, which inhibits the response of the CD62L+ T-cell subset.

INTRODUCTION: We synthesized sulfo-glycolipid, beta-SQAG9 (designate square beta-SQAG9 liposome, because it efficiently forms a liposome structure) that possessed immunosuppressive effects such as inhibition of T-cell responses in human allogeneic MLR and skin allograft survival in rats, and bound to CD62L (L-selectin) in vitro. In this study, we further investigated the immunosuppressive mechanism in vivo by beta-SQAG9 liposome in a skin-allografted rat model. METHODS: ACI rats (RT1(a)) were grafted skin of LEW rats (RT1(1)) treated with PBS or beta-SQAG9 liposome IV once a day for 7 days. Subsequently, we investigated the population of T cells and CD62L(+) T-cell subset in the spleen, axillary lymph nodes (ALNs), and peripheral blood of skin-allografted rats by two-color flow cytometry. RESULTS: Five of 11 (45.5%) rats that were treated with 50 mg/kg beta-SQAG9 liposome showed graft survival and another showed moderate rejection in graft. The CD62L(+) T-cell subset population in ALNs of beta-SQAG9 liposome-treated rats decreased in a dose-dependent manner. No significant difference in the T-cell population was observed between the beta-SQAG9 and control groups. These data suggest that beta-SQAG9 could bind to the CD62L(+) T-cell subset in vivo as well as in vitro and affect T-cell migration, which might lead to T-cell tolerance in vivo.

Local application of Aqua Titan improves symptoms of temporomandibular joint muscle disorder: a preliminary study.

Aqua Titan (AT), comprising microscopic titanium particles dispersed in water, has been reported to have beneficial effects on muscle tissue. This study investigated the effects of local application of AT on symptoms in patients with muscle disorders of the temporomandibular joint (TMJ) compared to patients with joint disorders of the TMJ. Sixteen patients with unilateral masseter muscle pain during motion (muscle disorder group) and six patients with unilateral TMJ pain during motion (joint disorder group) applied an AT-permeated patch over the painful area every night for 2 weeks. Symptoms were evaluated clinically at the initial visit and 1 and 2 weeks later. Clinical symptoms in the joint disorder group showed no tendency towards improvement after 2 weeks. In contrast, mouth opening range with/without pain, visual analogue scale (VAS) scores for pain during mouth opening and eating, and activities of daily living (ADL) scores in the muscle disorder group were improved significantly after 2 weeks. Multiple comparison tests in the muscle disorder group showed significant improvements in the VAS for eating and ADL score after 1 week. These results suggest that the AT patch has a potential supplementary role in the treatment of patients with muscle disorders of the TMJ.

Biological activities and quantitative structure-activity relationships of spiro[imidazolidine-4,4'(1'H)-quinazoline]-2,2',5(3'H)-triones as aldose reductase inhibitors.

A series of spiro[imidazolidine-4,4'(1'H)-quinazoline]- 2,2'5(3'H)-triones were prepared and tested for aldose reductase inhibitory activity. The 6'-halogenated derivatives were found to be highly potent in vitro inhibitors of male rabbit lens aldose reductase and in vivo inhibitors of polyol accumulation in the sciatic nerves of galactosemic rats. Of these, (4R)-6'-chloro-3'-methylspiro[imidazolidine-4,4'(1'H)-quinazoline] -2,2',5(3'H)-trione (67) showed the most potent in vitro and in vivo activities. An oral dose of 3 g/kg of compound 67 caused neither death nor behavioral abnormality in the preliminary acute toxicity study using mice and rats. Compound 67 was selected as a candidate for further evaluation. The quantitative structure-activity relationships in this series are also discussed.

Inhibitory effect of microfibril wheat bran on azoxymethane-induced colon carcinogenesis in CF1 mice.

Microfibril wheat bran (MFW), a processed dietary fiber prepared by milling of coarse wheat bran (WB), is softer and has a more pleasant taste than WB. In this study, we examined the inhibitory effect of MFW on azoxymethane (AOM)-induced colon carcinogenesis in female CF1 mice and compared its effect with that of WB and cellulose (CL). The mice were fed a modified AIN 76 A diet supplemented with either MFW, WB, or CL at a final concentration of 20% (w/w). Six weekly s.c. injections of AOM (10 mg/kg body weight) were administered per mouse commencing 1 week after the start of the feeding period. Control mice were injected with saline only. Thirty-three weeks after the initial injection, the mice were sacrificed, examined for tumors, and the cecal contents were analyzed to determine the moisture content and the concentrations of short-chain fatty acids (SCFA). The average number of total tumors per mouse in the MFW (2.9 +/- 0.6, P = 0.017) and WB (5.3 +/- 1.3, P = 0.373) diet groups was lower than that of the CL diet group (7.5 +/- 1.3), though there was no significant difference in tumor incidence (94.7%, 90.0% and 94.7%, respectively) between the groups. More than 90% of the tumors in each group were adenocarcinomas. The incidence of adenoma and that of carcinoma in situ in the MFW diet group (5.3% and 0%, respectively) were also lower than those in the CL diet group (26.3 and 26.3%, respectively; P = 0.180 and P = 0.046, respectively). Analysis of the cecal contents revealed a significantly higher moisture content and significantly higher concentrations of SCFA, butyrate in particular, in the MFW and WB diet groups. The results of this study indicate that the source and texture of dietary fiber can influence tumor development in CF1 mice, and more specifically that MFW is a promising and useful dietary supplement with properties serving to protect against the development of colon cancer.

Carinal reconstruction with a Y-shaped collagen-conjugated prosthesis.

BACKGROUND: Carinal reconstruction by direct suturing is associated with a high mortality because high tension at the anastomosis can lead to tracheobronchial fistula. A new tracheal prosthesis was therefore designed for reconstruction of the tracheal bifurcation and applied for experimental carinal replacement in dogs. METHODS: The main frame of the new prosthesis consists of a Y-shaped Marlex mesh tube (C.R. Bard, Inc, Billerica, Mass) reinforced with polypropylene spirals, to which collagen extracted from porcine skin is chemically conjugated to provide biocompatibility and airtightness. This conjugated collagen is composed of amorphous and sponge collagen layers. The tracheobronchial bifurcation was replaced with the prosthesis in 10 beagle dogs. RESULTS: Eight dogs survived the postoperative period, and 2 dogs died within 4 days after the operation. Bronchoscopic examination revealed that the tracheal prosthesis was covered with smooth whitish tissue and that no stenosis or dehiscence was present in the 8 dogs even 6 months after the operation. Slight mesh exposure was recognized in 1 dog. Histologic examination revealed that approximately one half of the luminal surface was covered with ciliated columnar epithelium or nonciliated squamous epithelium. In the remaining lumen, especially in the middle portion of the prosthesis, connective tissue without epithelium was observed. CONCLUSIONS: These long-term results indicate that our bifurcated tracheal prosthesis can be used for reconstruction of the tracheobronchial bifurcation with long-term safety.

Immunosuppressant-free allotransplantation of the trachea: the antigenicity of tracheal grafts can be reduced by removing the epithelium and mixed glands from the graft by detergent treatment.

OBJECTIVE: To develop a method for eliminating the epithelium and mixed glands from tracheal grafts by detergent treatment and evaluate these grafts for immunosuppressant-free allotransplantation in dogs. METHODS: Fresh canine tracheal grafts were treated with a detergent (1% Triton X-100 t-octylphenoxypolyethoxyethanol; T-9284; Sigma Chemical Co, St Louis, Mo) at 4 degrees C for 48 hours. The grafts were then used for intrathoracic 5-ring tracheal replacement in other dogs without immunosuppressant treatment (n = 6, detergent treatment group). In the control group (n = 6) fresh untreated canine tracheal segments were implanted as allografts. All the implanted grafts were covered with an omental pedicle. RESULTS: In the detergent treatment group the chondrocytes in the graft had a similar appearance to those in the fresh trachea, indicating that the chondrocytes remained viable after the detergent treatment. In 5 of the 6 grafts, the epithelium and mixed glands had been removed completely. After transplantation, these 5 grafts were incorporated by the host trachea without stenosis. In the remaining treated tracheal graft, in which removal of the epithelium was incomplete, moderate stenosis was observed at the fourth week after implantation, although this was not progressive. In the control group, granulation tissue of the graft and significant stenosis were observed after transplantation. CONCLUSION: The antigenicity of tracheal grafts can be greatly reduced by removing the epithelium and mixed glands by the use of detergent treatment. The epithelium and mixed glands of the graft appear to be the determining elements involved in rejection after tracheal allotransplantation.