Liposomal bupivacaine versus conventional anesthetic or placebo for hemorrhoidectomy: a systematic review and meta-analysis

BACKGROUND

Liposome bupivacaine (LB) is a long-acting anesthetic to enhance postoperative analgesia. Studies evaluating the efficacy of the LB against an active comparator (bupivacaine or placebo) on acute postoperative pain control in hemorrhoidectomy procedures are few and heterogeneous. Therefore, we performed a systematic review and meta-analysis comparing LB's analgesic efficacy and side effects to conventional/placebo anesthetic in hemorrhoidectomy patients.

METHODS

We performed a systematic review and meta-analysis of randomised controlled trials investigating the use of LB after haemorrhoidectomy. We searched the literature published from the time of inception of the datasets to August 19, 2022. The electronic databases included English publications in Ovid MEDLINE In-Process & Other Non-Indexed Citations, Ovid MEDLINE, Ovid EMBASE, and Scopus.

RESULTS

A total of 338 patients who underwent a hemorrhoidectomy procedure enrolled in three randomized clinical trials were included. The overall mean age was 45.84 years (SD ± 11.43), and there was a male predominance (53.55% male). In total 194 patients (52.2%) received LB and 144 (47.8%) received either bupivacaine or placebo. Pain scores at 72 h in the LB (199, 266, and 300 mg) were significantly lower than in the bupivacaine HCl group (p = 0.002). Compared to the bupivacaine/placebo group, the time to first use of opioids in the LB group was significantly longer at LB 199 mg (11 h vs. 9 h), LB 266 mg (19 h vs. 9 h), and LB 300 mg (19 h vs. 8 h) (p < 0.05). Moreover, compared to the bupivacaine/epinephrine group, it was significantly lower in the LB 266 mg group (3.7 vs. 10.2 mg) and at LB 300 mg (13 vs. 33 mg) (p < 0.05). Finally, regarding adverse effects, the conventional anesthetic/placebo group reported more pain in bowel movement than LB groups (OR 2.60, 95% CI 1.31-5.16).

CONCLUSIONS

Comparing LB to conventional anesthetic/placebo anesthetic for hemorrhoidectomy, we found a statistically significant reduction in pain through 72 h, decreased opioid requirements, and delayed time to first opioid use. Moreover, the conventional anesthetic/placebo group reported more pain in bowel movement than LB groups.

Reallocating desk workers' sitting time to standing or stepping: associations with work performance

BACKGROUND

Studies have suggested that sitting time at work may lead to underperformance but they may underestimate the benefits to desk workers' performance of reducing occupational sitting time without considering the relative effects of the specific activities replaced.

AIMS

To estimate differences in work performance (presenteeism, absenteeism and engagement) when occupational sitting time is reallocated to standing/stepping in desk workers.

METHODS

Data for middle-aged desk workers were from a Japan-wide online survey (n = 2228). Self-report proportion of occupational sitting and standing/stepping, work hours and work performance indicators, including absolute (ratings relating only to self) and relative (ratings of self, compared to others) presenteeism and absenteeism, and dimensions of work engagement, were collected. Partition and isotemporal substitution models were used to investigate the associations of occupational sitting and standing/stepping time with work performance, including their reallocation effects.

RESULTS

In partition models, longer occupational sitting time was associated with a lower absolute presenteeism score (i.e. less productivity), lower absolute absenteeism (i.e. longer-than-expected work hours), and lower engagement. Longer occupational standing/stepping time was associated with lower absolute absenteeism and more engagement. Isotemporal substitution models showed that each hour of occupational sitting reallocated to standing/stepping was favourably associated with overall work engagement (B = 0.087; 95% confidence interval 0.051, 0.122) and its dimensions (B ranged from 0.078 to 0.092), but was not associated with presenteeism or absenteeism.

CONCLUSIONS

These findings suggest that management support and practical initiatives to encourage desk workers to replace portions of their sitting time with standing/stepping may contribute to enhanced work engagement.

P932Structural changes in left ventricle after transcatheter aortic valve implantation

Background

Transcatheter aortic valve implantation (TAVI) has improved prognosis and quality of life of patients with severe aortic stenosis (AS) who had been considered inoperable or at high risk for surgical aortic valve replacement reflecting their age, frailty, and comorbidities. However, less is known about changes in cardiac geometry after TAVI procedure, and predictors of them.

Purpose

To clarify changes in cardiac geometry after TAVI, and their predictors.

Methods

We retrospectively analyzed patients with severe AS who underwent TAVI in our institute between May 2016 and June 2018. Of the 117 consecutive patients enrolled to this study, 12 patients died before six-month follow up, and finally 88 patients received follow up exams including echocardiography at six months after TAVI procedure.

Results

The analysis of echocardiographic data at the baseline and the six-month follow up of the 88 patients (age 86.2±4.0 years, male 19.3%, STS-PROM 6.76±3.28%, peak aortic jet velocity 4.67±0.75m/s) revealed that left ventricular end-diastolic volume index (LVEDVi) (from 80.1±20.9ml/m2to 74.2±15.9ml/m2, p=0.011), and left ventricular mass index (LVMi) (from 116.0±32.7g/m2to 93.6±25.6g/m2, p<0.001) had improved in six months after TAVI procedure. The difference of LVEDVi (ΔLVEDVi: six-month LVEDVi–baseline LVEDVi) and the difference of LVMi (ΔLVMi: six-month LVMi – baseline LVMi) were significantly higher in the patients with chronic atrial fibrillation compared to the rest (ΔLVEDVi: +7.7±8.7ml/m2 vs −7.2±18.1ml/m2, p=0.024; ΔLVMi: +7.1±11.5g/m2 vs −25.3±33.5g/m2, p=0.008). In echocardiographic data, ΔLVEDVi and ΔLVMi both had positive correlation between baseline E/e' ratio (ΔLVEDVi: r=0.224, p=0.048; ΔLVMi: r=0.240, p=0.034), and negative correlation between baseline LVEDVi (ΔLVEDVi: r=−0.674, p<0.001; ΔLVMi: r=−0.312, p=0.003), LVMi (ΔLVEDVi: r=−0.422, p<0.001; ΔLVMi: r=−0.699, p<0.001), peak aortic jet velocity (ΔLVEDVi: r=−0.257, p=0.016; ΔLVMi: r=−0.376, p<0.001), and mean transaortic pressure gradient (ΔLVEDVi: r=−0.269, p=0.011; ΔLVMi: r=−0.403, p<0.001).

Conclusion

TAVI resulted in reverse remodeling and regression of hypertrophy in left ventricle. And these improvement were grater in patients with more advanced left ventricular remodeling and hypertrophy, and higher severity of AS at the baseline, however, less in patients with chronic atrial fibrillation and worse diastolic dysfunction.

Cartilage wear patterns in severe osteoarthritis of the trapeziometacarpal joint: a quantitative analysis

OBJECTIVE

The present quantitative study aimed to assess the three-dimensional (3-D) cartilage wear patterns of the first metacarpal and trapezium in the advanced stage of osteoarthritis (OA) and compare cartilage measurements with radiographic severity.

DESIGN

Using 19 cadaveric trapeziometacarpal (TMC) joints, 3-D cartilage surface models of the first metacarpal and trapezium were created with a laser scanner, and 3-D bone surface model counterparts were similarly created after dissolving the cartilage. These two models were superimposed, and the interval distance on the articular surface as the cartilage thickness was measured. All measurements were obtained in categorized anatomic regions on the articular surface of the respective bone, and we analyzed the 3-D wear patterns on the entire cartilage surface. Furthermore, we compared measurements of cartilage thickness with radiographic OA severity according to the Eaton grading system using Pearson correlation coefficients (r).

RESULTS

In the first metacarpal, the cartilage thickness declined volarly (the mean cartilage thickness of the volar region was 0.32 ± 0.16 mm, whereas that of the dorsal region was 0.53 ± 0.18 mm). Conversely, the cartilage evenly degenerated throughout the articular surface of the trapezium. Measurements of the categorized regions where cartilage thinning was remarkable exhibited statistical correlations with radiographic staging (r = -0.48 to -0.72).

CONCLUSIONS

Our findings indicate that cartilage wear patterns differ between the first metacarpal and trapezium in the late stage of OA. There is a need for further studies on cartilage degeneration leading to symptomatic OA in the TMC joint.

X-Ray Spectrometer for EXAFS Using a Position Sensitive Detector

An active recording x-ray crystal spectrometer for extended x-ray absorption fine structure (EXAFS) has been built using a position sensitive detector of the self scanning photodiode array (SSPA) type. The SSPA detector has energy and position sensitivity for x-rays. The spectrometer was applied to the measurement for EXAFS of the several compounds in foil, powder and liquid states. The spectra can be obtained rapidly, and compare very well with other methods. We found that the SSPA detector is very useful for the measurement of EXAFS.

Probing ultrafast spin-relaxation and precession dynamics in a cuprate Mott insulator with seven-femtosecond optical pulses

A charge excitation in a two-dimensional Mott insulator is strongly coupled with the surrounding spins, which is observed as magnetic-polaron formations of doped carriers and a magnon sideband in the Mott-gap transition spectrum. However, the dynamics related to the spin sector are difficult to measure. Here, we show that pump-probe reflection spectroscopy with seven-femtosecond laser pulses can detect the optically induced spin dynamics in Nd2CuO4, a typical cuprate Mott insulator. The bleaching signal at the Mott-gap transition is enhanced at ~18 fs. This time constant is attributable to the spin-relaxation time during magnetic-polaron formation, which is characterized by the exchange interaction. More importantly, ultrafast coherent oscillations appear in the time evolution of the reflectivity changes, and their frequencies (1400-2700 cm-1) are equal to the probe energy measured from the Mott-gap transition peak. These oscillations can be interpreted as the interference between charge excitations with two magnons originating from charge-spin coupling.

Educational effects using a robot patient simulation system for development of clinical attitude

INTRODUCTION

The aim of this study was to assess the effectiveness of improving the attitude of dental students towards the use of a full-body patient simulation system (SIMROID) compared to the traditional mannequin (CLINSIM) for dental clinical education.

MATERIALS AND METHODS

The participants were 10 male undergraduate dental students who had finished clinical training in the university hospital 1 year before this study started. They performed a crown preparation on an upper pre-molar tooth using SIMROID and CLINSIM as the practical clinical trials. The elapsed time for preparation was recorded. The taper of the abutment teeth was measured using a 3-dimensional shape-measuring device after this trial. In addition, a self-reported questionnaire was collected that included physical pain, treatment safety and maintaining a clean area for each simulator. Qualitative data analysis of a free format report about SIMROID was performed using text mining analysis. This trial was performed twice at 1-month intervals.

RESULTS

The students considered physical pain, treatment safety and a clean area for SIMROID significantly better than that for CLINSIM (P < .01). The elapsed time of preparation in the second practical clinical trial was significantly lower than in the first for SIMROID and CLINSIM (P < .01). However, there were no significant differences between the abutment tapers for both systems. For the text mining analysis, most of the students wrote that SIMROID was similar to real patients.

CONCLUSION

The use of SIMROID was proven to be effective in improving the attitude of students towards patients, thereby giving importance to considerations for actual patients during dental treatment.

Altered bone density and stress distribution patterns in long-standing cubitus varus deformity and their effect during early osteoarthritis of the elbow

OBJECTIVE

To quantify the bone density and stress distribution patterns in long-standing cubitus varus and clarify the effects of the deformity on bone density.

DESIGN

We created three-dimensional computed tomography (CT) elbow models from 21 patients with long-standing cubitus varus deformities without advanced osteoarthritis (OA) and assessed the deformity by superimposing the affected humerus onto a mirror-image of the contralateral normal. Elbows were divided into 13 regions before measuring the bone density of each region and comparing the percentage of high-density volume (%HDV) between affected and normal sides. We constructed finite element models and quantitatively analyzed stress distribution.

RESULTS

Average degrees of deformities were 20.1° of varus, 6.4° of extension, and 12.7° of internal rotation. The medial side of the affected humerus and ulna, Anteromedial trochlea (P < 0.001), Medial coronoid (P = 0.004), and Medial olecranon (P = 0.049) had significantly higher %HDVs than their normal counterparts. Conversely, %HDVs on the affected lateral side, Capitellum (P < 0.001), Anterolateral trochlea (P = 0.010), Posterolateral trochlea (P < 0.001), Lateral coronoid (P = 0.007), and Lateral olecranon (P < 0.001) were significantly lower than the normal side. The affected radial head %HDVs at Anterolateral and Posteromedial quadrants were high (P = 0.007) and low (P = 0.007), respectively. The bone density distribution coincided with stress distribution patterns revealed by finite element analysis (FEA), except in the lateral region influenced by forearm rotation.

CONCLUSIONS

Repetitive stress on the medial elbow may alter bone density distribution patterns, probably presenting from early stage of OA.

Accuracy of self-reported height, weight and waist circumference in a Japanese sample

Objective

Inconsistent results have been found in prior studies investigating the accuracy of self‐reported waist circumference, and no study has investigated the validity of self‐reported waist circumference among Japanese individuals. This study used the diagnostic standard of metabolic syndrome to assess the accuracy of individual's self‐reported height, weight and waist circumference in a Japanese sample.

Methods

Study participants included 7,443 Japanese men and women aged 35–79 years. They participated in a cohort study's baseline survey between 2007 and 2011. Participants' height, weight and waist circumference were measured, and their body mass index was calculated. Self‐reported values were collected through a questionnaire before the examination.

Results

Strong correlations between measured and self‐reported values for height, weight and body mass index were detected. The correlation was lowest for waist circumference (men, 0.87; women, 0.73). Men significantly overestimated their waist circumference (mean difference, 0.8 cm), whereas women significantly underestimated theirs (mean difference, 5.1 cm). The sensitivity of self‐reported waist circumference using the cut‐off value of metabolic syndrome was 0.83 for men and 0.57 for women.

Conclusions

Due to systematic and random errors, the accuracy of self‐reported waist circumference was low. Therefore, waist circumference should be measured without relying on self‐reported values, particularly in the case of women.

Increased Sensitivities of Peripheral Blood Mononuclear Cells to Immunosuppressive Drugs in Cirrhosis Patients Awaiting Liver Transplantation

Successful immunosuppressive therapy is critical for liver transplantation. However, a considerable number of patients show clinical resistance to the therapy and experience rejection episodes, or alternatively exhibits serious adverse effects of drugs. We examined the in vitro response of peripheral blood mononuclear cells (PBMCs) to immunosuppressive drugs in cirrhosis patients awaiting liver transplantation. We evaluated the suppressive efficacy of prednisolone, methylprednisolone, cyclosporine, and tacrolimus on the in vitro blastogenesis of PBMCs obtained from 22 cirrhosis patients and 31 healthy subjects. In vitro drug concentrations giving 50% inhibition of PBMC blastogenesis (IC50s) were calculated. Two out of these 22 patients received liver transplantation from living donors, and their clinical courses were surveyed until 5 weeks after operation. The median IC50 values for prednisolone, cyclosporine, and tacrolimus against blastogenesis of PBMCs from cirrhosis patients were significantly lower than those of PBMCs from healthy subjects (p < 0.01). However, large individual differences were observed in the IC50 values of the immunosuppressive drugs examined, especially in the cirrhosis patients. One recipient exhibiting high PBMC sensitivity to tacrolimus (IC50 = 0.001 ng/ml) showed good clinical course without rejection until 5 weeks after liver transplantation. The other recipient exhibiting relatively low PBMC sensitivity to taclolimus (IC50 = 0.30) showed allograft rejection at 1 week after operation. We concluded from these observations that PBMCs of cirrhosis patients are vulnerable to the immunosuppressive effects of prednisolone and calcineurin inhibitors. However, large individual variations in the IC50 values suggest that patients exhibiting relatively lower sensitivity to these drugs may have risks of rejection, whereas highly sensitive patients are possibly able to reduce the dose of immunosuppressive drugs to avoid serious drug-adverse effects, after liver transplantation.

Abstract OT3-07-02: Influence of exercise or educational programs on long-term physical activity by patients after surgery for primary breast cancer: A randomized trial

[Background]

Past studies revealed that a moderate to high level of physical activity after diagnosis of breast cancer reduces both the risk of breast cancer-related death and death from all causes. Furthermore, some randomized studies suggested that exercise programs improve the percentage of patients who complete the chemotherapy and quality of life, and decrease fatigue, and adverse events. The issues to be determined include defining an established uniform exercise program and the efficacy of a long-term exercise program after breast cancer surgery.

[Object] To elucidate the efficacy of a long-term exercise program and to verify the safety and feasibility of a uniform exercise program using an ‘existing social resource’ after primary therapy of breast cancer.

[Design] A multi-center, randomized trial.

[Method] Subjects: The subjects included patients who had completed treatment for primary breast cancer, including surgery and/or adjuvant chemotherapy. Patients with metastatic breast cancer were excluded.

Randomization & intervention: The patients were randomly assigned to three groups.

The first group followed an exercise program at Curves® that involved 30 minutes of exercise, including aerobics, weight training, and stretching 3 times a week for 4 months. The second group was given life-style guidance at least once that patients participate in a lecture program about recommended exercise at this point and the importance of weight control after diagnosis of breast cancer using a brochure. The third group served as controls that the patients receive a brochure used same one in the second group. The variables included age and weight.

Outcome: The primary endpoint is level of physical activity at 1 year after randomization, and the secondary endpoints are the percentage of those completing the exercise program, patient reported outcomes (QOL, cancer or treatment associated symptoms, fatigue, depression, and anxiety), body mass index, bone density, and level of lymphedema.

Period of research: The study will last 2 years beginning March 2016.

Sample size: We plan to enroll 400 patients to detect 20% difference with 90% power.

Additional study: Some biochemical markers in the blood will be evaluated to determine the mechanism of the effect of exercise on the human body.

Citation Format: Kawada K, Taira N, Hatono M, Takahashi Y, Miyoshi Y, Nogami T, Iwamoto T, Motoki T, Sien T, Matsuoka J, Doihara H, Ikeda M, Ogasawara Y, Takabatake D, Yoshitomi S, Kiyoto S, Yamamoto S, Mizota Y, Oka K. Influence of exercise or educational programs on long-term physical activity by patients after surgery for primary breast cancer: A randomized trial [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT3-07-02.

Picosecond rotation of a ring-shaped optical lattice by using a chirped vortex-pulse pair

A novel method of ultrafast rotation of a ring-shaped optical lattice in the picosecond time region was proposed and demonstrated. Our ring-lattice generator was assembled by a pair of linearly chirped pulses with a time delay, a high-order birefringent retarder, and an axially symmetric polarization element. Using a mode-locked Ti:sapphire laser oscillator as a light source, stable two-, four-, and six-petaled ring-lattice rotations were demonstrated with the rotation periods of 1.6, 3.2, and 4.8 ps, respectively. Our method has the potential to open up a new technique to resonantly excite propagating quasi-particles together with their coherent enhancement.

Safety assessment of the Clostridium butyricum MIYAIRI 588® probiotic strain including evaluation of antimicrobial sensitivity and presence of Clostridium toxin genes in vitro and teratogenicity in vivo

Probiotics are live microorganisms ingested for the purpose of conferring a health benefit on the host. Development of new probiotics includes the need for safety evaluations that should consider factors such as pathogenicity, infectivity, virulence factors, toxicity, and metabolic activity. Clostridium butyricum MIYAIRI 588® (CBM 588®), an anaerobic spore-forming bacterium, has been developed as a probiotic for use by humans and food animals. Safety studies of this probiotic strain have been conducted and include assessment of antimicrobial sensitivity, documentation of the lack of Clostridium toxin genes, and evaluation of CBM 588® on reproductive and developmental toxicity in a rodent model. With the exception of aminoglycosides, to which anaerobes are intrinsically resistant, CBM 588® showed sensitivity to all antibiotic classes important in human and animal therapeutics. In addition, analysis of the CBM 588® genome established the absence of genes for encoding for α, β, or ε toxins and botulin neurotoxins types A, B, E, or F. There were no deleterious reproductive and developmental effects observed in mice associated with the administration of CBM 588®. These data provide further support for the safety of CBM 588® for use as a probiotic in animals and humans.

How to Embolize Wide-Necked Aneurysms?

Novel endovascular approaches are needed for safer and more definitive treatment of wide-necked aneurysms, to overcome the limitations of the Guglielmi detachable coil (GDC) system and further, the application of this technique.

The double GDC technique (DGT), for embolization of wide-necked aneurysms, and the combination of stent placement and coil deposition (CTSC) for management of fusiform aneurysms have been developed and their usefulness is reviewed. The DGT involves scaffolding of a GDC coil to form a stabilizing frame inside the aneurysmal neck and then positioning of a second coil to reinforce the first coil. After confirming the absence of coil herniation in the parent artery, both coils are released together. A patient with a wide-necked large aneurysm of the left internal carotid artery was treated using this technique, and followed up angiographically and clinically for a period of three months. The follow-up angiograms revealed complete embolization of the aneurysm.

The patient had no neurological changes or adverse events during the procedure. The CTSC involves reconstructing the artery with a stent and packing the aneurysm lumen with GDCs through the stent interstices. A patient with a dissecting fusiform aneurysm of the vertebral artery associated with hypoplasia of the contralateral vertebral artery was treated using this technique to prevent rebleeding. His clinical course was uneventful over a six-month follow-up period. Angiography performed two months after the procedure confirmed excellent flow through the right vertebral artery and absence of filling of the daughter aneurysm.

Decreased expression of Met during differentiation in rat lung

Organ-specific stem cells play key roles in maintaining the epithelial cell layers of lung. Bronchioalveolar stem cells (BASCs) are distal lung epithelial stem cells of adult mice. Alveolar type 2 (AT2) cells have important functions and serve as progenitor cells of alveolar type 1 (AT1) cells to repair the epithelium when they are injured. Hepatocyte growth factor (HGF) elicits mitogenic, morphogenic, and anti-apoptotic effects on lung epithelial cells through tyrosine phosphorylation of Met receptor, and thus is recognized as a pulmotrophic factor. To understand which cells HGF targets in lung, we identified the cells expressing Met by immunofluorescence assay. Met was strongly expressed in BASCs, which expressed an AT2 cell marker, pro-SP-C, and a club cell marker, CCSP. In alveoli, we found higher expression of Met in primary AT2 than in AT1 cells, which was confirmed using primary AT2 cells. We further examined the mitogenic activity of HGF in AT2-cell-derived alveolar-like cysts (ALCs) in 3D culture. Multicellular ALCs expressed Met, and HGF enhanced the ALC production. Taking these findings together, BASCs could also be an important target for HGF, and HGF-Met signaling could function more potent on cells that have greater multipotency in adult lung.

Pharmacology in a Cup of Coffee The Virtue of Coffee and Vitamins Learned from the History of Scurvy and Dropsy

Scurvy, a vitamin C deficiency, was rampant during the age of discovery in Europe. In the mid-17th century, “Pasqua Rosée,” the first coffee house in London, put an ad in the newspaper “Publick Adviser” clearly stating, “It (coffee) is excellent to prevent and cure dropsy, gout, and scurvy.” A Netherlands trade merchant carried the information to Nagasaki, Japan, along with coffee beans harvested in the Netherlands’ new territory, Java Island. A Japanese physician in Nagasaki, Dr. Kai Hirokawa, translated the information into Japanese in his new book, “Dutch Medicines,” published in 1803. According to the ancient documents stored in Wakkanai City, Japan, the coffee beans were distributed to Tsugaru Clan soldiers who were guarding the northern coastline from 1855 to 1856. The purpose of the distribution was the prevention of scurvy and dropsy. As the result, none of the soldiers died from scurvy during the winter of 1855-1856. This paper discusses the pharmacological relationship between coffee micronutrients and vitamin deficiency syndrome.

A histological study on microthrombi in autopsy cases of DIC

Microthrombi in 43 untreated and 26 treated cases of DIC were studied histologically and immunohistochemically. In the untreated cases, four types of microthrombi (intraluminal microthrombi with or without fibroblastic and/or smooth muscle cell reaction) were identified. Microthrombi in the former three types showed various degrees of thrombolysis. Failure of thrombolysis seemed to lead the organization of microthrombi. These morphological findings were considered to indicate the course of DIC and the degree of disappearance of the microthrombi in DIC. Microthrombi in the hepatic sinusoids and glomerular capillaries were studied with special reference to the removal processes of the microthrombi. Pathogenesis of renal cortical necrosis in DIC was also discussed. The number of microthrombi was markedly decreased by heparin and gabexate mesilate treatment. The incidences of microthrombi in the liver, kidney, lung, and heart were compared in the two treated groups.

Immunohistochemical expression of fibrillin-1 and fibrillin-2 during tooth development

BACKGROUND AND OBJECTIVE

Oxytalan fibers are categorized as a microfibril assembly without elastin deposition, and are unique components in the periodontal ligament (PDL). However, little is known about their formation during PDL development. To clarify the mechanisms of oxytalan fiber formation in developing PDL, we performed immunohistochemical analysis to detect the direct expression of fibrillin-1 and fibrillin-2, which are major components of microfibrils.

MATERIAL AND METHODS

Frozen sections of lower molars from mice at several stages of growth were prepared without chemical fixation and decalcification using the film transfer method. Immunostaining was performed with anti-fibrillin-1 and -2, and anticytokeratin antibodies.

RESULTS

Fibrillin-1 was not expressed in the dental follicle during the crown forming stage. At postneonatal day 9, fibrillin-1 expression started with meshwork appearance between the epithelial cells from Hertwig's epithelial root sheath at the root dentin surface. Fibirillin-2 was detected much earlier than fibrillin-1 expression. Fibrillin-2 was expressed with a liner appearance, running parallel to the root axis in PDL, and was partially co-expressed with cytokeratin 14 expression in Hertwig's epithelial root sheath. Furthermore, we detected both fibrillin-1 and fibrillin-2 expression in human PDL. Fibrillin-1 was detected in fibers with a vertically oriented root axis in PDL. Fibrillin-2 was widely expressed in PDL, including around the epithelial cell rests of Malassez. Fibrillin-1 and fibrillin-2 were clearly co-expressed in thick fiber structures in human PDL.

CONCLUSION

Our results suggest that both fibrillin-1 and fibrillin-2 expression is required to form thick oxytalan fibers in PDL. Based on the expression patterns for fibrillin-1 and fibrillin-2, they have different functions during tooth root and PDL development. Early expression of fibrillin-2 may regulate dental epithelial cell behavior during root and PDL development.