Yong-Chan Lee

Accelerated healing with the use of a silk fibroin membrane for the guided bone regeneration technique.

OBJECTIVE The purpose of this study was to evaluate the bone regeneration ability of silk fibroin (SF) membrane. STUDY DESIGN Fourier-transform infrared (FT-IR) and solubility test against distilled water were performed with 3 different types of SF membrane (SM1, SM2, and SM3). Subsequently, microscopic computerized tomography (μ-CT) and histomorphometric analyses were performed in rabbit calvarial defect model after SF membrane application at 4 and 8 weeks after surgery. RESULTS FT-IR showed that the conformation of the SF membrane was a random coil structure and that SM1 was the least soluble. When SM1 was used in the animal model, the groups with SM1 had significantly higher new bone formation than the uncovered control in both the μ-CT and the histomorphometric analyses (P < .05). CONCLUSIONS The SF membrane had more new bone formation compared with the uncovered control.

Sialolipoma: case report and review of 27 cases

IntroductionThis article presents a patient with sialolipoma of the submandibular gland, a rare neoplasm, and reviews related literatures. A MEDLINE literature and articles published in the Korean language in KMbase (kmbase.medric.or.kr) search was performed and the literatures were reviewed.DiscussionWe presented a sialolipoma of the submandibular gland and other 27 cases from published literatures. Our case was shown in 62-year-old female. It was the second case of submandibular gland sialolipoma reported in the English literature. Unlike other lipomatous lesion in the oral cavity, definite male predilection was not observed in the sialolipoma. The most common site for the tumor was the parotid gland (17 cases, 60.7%), followed by the palate (four cases, 14.2%). Histopathologically, a tumor was a benign lesion with proliferating lipocytes including scattered foci with a normal salivary gland tissue. Our treatment of choice was surgical excision and recurrent case has not been reported.ConclusionSialolipoma is a rare benign neoplasm in the head and neck and it shows equal sex predilection.

Restoration of a peri-implant defect by platelet-rich fibrin

OBJECTIVE The objective of this study was to evaluate the application of platelet-rich fibrin (PRF) into a peri-implant defect in vivo. STUDY DESIGN Eight New Zealand white rabbits were used for this study. Two peri-implants with defects sized 3.0 × 5.0 mm (width × length) were prepared after drilling to host the dental implant in the tibia. Subsequently, the 2 dental implants were installed (diameter, 3.0 mm and length, 8.0 mm). In the experimental group, PRF was applied into the bony defect. In the control group, the peri-implant defect was left unfilled. The animals were humanely killed 8 weeks after implantation and histomorphometric analysis was done. RESULTS In the histomorphometric analysis, mean new bone formation was 29.30% ± 7.50% in the experimental group and 11.06% ± 8.94% in the control group (P = .020). Mean bone-to-implant contact was 39.43% ± 7.39% in the experimental group and 17.11% ± 8.12% in the control group (P = .006). CONCLUSIONS In the animal model, peri-implant defect sized 3.0 × 5.0 mm (width × length) was successfully repaired by the application of PRF alone.

Aerosol Deposition of Hydroxyapatite and 4-Hexylresorcinol Coatings on Titanium Alloys for Dental Implants

PURPOSE Aerosol deposition is a newly developed technique, and it can deliver the drug from a hydroxyapatite (HA)-coated surface. 4-Hexylresorcinol (4-HR) is a well-known antiseptic. The influence of the 4-HR component of HA coatings on titanium surfaces was studied in vitro and in vivo. MATERIALS AND METHODS X-ray diffraction and Fourier transform infrared techniques were used for the evaluation of the coating. The cellular response of the coating was evaluated by scanning electron microscopic study, MTT assay, alkaline phosphatase assay, and osteocalcin assay. In addition, the dental implant was coated with HA or HA + 4-HR. The implant was installed into the tibia of a rabbit after contamination by Aggregatibacter actinomycetemcomitans. The torque test and histologic analysis were then performed at 8 weeks after the operation. RESULTS By use of an aerosol deposition technique, the combination of HA and 4-HR was successfully coated onto a titanium surface, which was confirmed by x-ray diffraction and Fourier transform infrared techniques. MG63 cells attached more rapidly to the HA + 4-HR coating than to the HA-only coating. The HA + 4-HR coating had significantly increased osteocalcin expression and alkaline phosphatase activity compared with the HA-only coating (P < .05). The dental implant coated with HA + 4-HR had a significantly higher removal torque value than that coated with HA alone at 8 weeks after surgery (P < .05). On histologic analysis, both the bone formation value and the bone-to-implant contact value were significantly higher in the HA + 4-HR group than in the HA-only group at 8 weeks after surgery (P < .05). CONCLUSIONS Collectively, the HA + 4-HR-coated dental implant had clear advantages over the HA-coated dental implant. Therefore HA + 4-HR coatings can be considered for patients who need immediate implant installation after tooth extraction or who have poor-quality bone.

Creutzfeldt-Jakob disease with the V203I mutation and M129V polymorphism of the prion protein gene (PRNP) and a 17 kDa prion protein fragment

Human prion diseases are fatal neurodegenerative disorders that include kuru, Gerstmann-Sträussler-Scheinker disease, fatal familial insomnia and Creutzfeldt-Jakob disease (CJD). They are characterized by the accumulation of an abnormal protease-resistant isoform of the prion protein, PrP, spongiform neurodegeneration, astrogliosis and neuronal cell loss [1]. CJD occurs in sporadic, genetic, infectious and iatrogenic forms. About 85% of all CJD cases are sporadic. Approximately 10–15% of CJD cases are inherited, and less than 1% are acquired by transmission. Human prion protein contains 253 amino acids encoded by the prion protein gene (PRNP), located on chromosome 20p12 in humans. PRNP plays an important role in conferring susceptibility or resistance to prion disease. A number of point or insertional mutations in the open reading frame of PRNP are linked to the genetic forms of CJD [2]. In addition to pathogenic mutations, polymorphisms at codons 129 or 219 of PRNP influence susceptibility to prion diseases and determine disease phenotype [3]. A CJD patient with a point mutation at codon 203 of PRNP, yielding the substitution of Val by Ile (V203I) and Met/Met homozygosity at codon 129 was reported previously [4]. Here we report the first analysis of a CJD case with V203I mutation and codon 129 Met/Val (M129V) heterozygosity. A 66-year-old Korean woman, with no family history of prion diseases, developed gait disturbance and rapidly progressive cognitive dysfunction. Three weeks after the onset, she was admitted to our hospital. She was alert, and her score on the Mini-Mental State Examination was 29 points. She showed dystonic posturing of both hands, leftside dominant resting and postural tremor, mild bradykinesia, cogwheel rigidity and incontinence of urine. Brain magnetic resonance imaging (MRI) revealed no specific findings (Figure 1A,C). Cerebrospinal fluid (CSF) study did not show any signs of infection of the central nervous system. Three days after admission, she had severe voiding difficulty. To investigate the possibility of hydrocephalus, cisternography was done; evidence of hydrocephalus was not seen. One month after onset, she had myoclonic jerks. Her mental and neurologic disturbances gradually worsened. Five weeks after onset, she had frequent myoclonus, dysphonation, aggravation of dysphagia and quadriparesis. Repeat MRI examination at that time revealed gyriform hyperintensity in the cerebral cortex on diffusion-weighted images (Figure 1B) and T2-weighted images (Figure 1D). Six weeks after onset, she began to have dyspnoea. The patient’s condition deteriorated rapidly to reach a stuporous state with impaired comprehension. The patient died 2 months after onset of clinical signs. An autopsy was performed. Total brain weight was 1450 g. One half of the autopsy brain was immediately frozen, the other half was used for neuropathological examination. Formalin-fixed, paraffinembedded tissue blocks from frontal and temporal lobes as well as basal ganglia and cerebellum were processed for haematoxylin and eosin staining and immunohistochemistry. The immunohistochemical staining was performed with either monoclonal anti-PrP 3F4 antibody or polyclonal antibody for glial fibrillary acidic protein. Post mortem neuropathological examination revealed moderate spongiform degeneration and vacuoles in the frontal cortex (Figure 1E). Slight neuronal loss and moderate astrogliosis were also observed in the frontal cortex (Figure 1F). Immunohistochemical staining for PrP using 3F4 antibody showed patterns of synaptic deposition and patchy deposits in the frontal lobes and temporal lobes (Figure 1G,H). Intraand peri-neuronal deposits were seen in the basal ganglia (Figure 1I). Punctuate deposits of PrP were seen in the granular layer of the cerebellum (Figure 1J). No plaque-like deposits of PrP were detected. In addition, mild spongiform degeneration and large vacuoles were observed in all regions analysed. After obtaining informed consent, blood samples were collected from the patient with the mutation at codon 203, from 240 sporadic CJD patients and from 543 healthy Koreans [5,6]. The study was approved by the Institutional Review Board of Hallym University Sacred Heart Hospital. Genomic DNA was extracted from blood

PRNP 1368 polymorphism is not associated with sporadic Creutzfeldt‐Jakob disease in the Korean population

Background:  Human prion protein gene (PRNP) is considered a critical and fundamental gene in determining the incidence of human prion diseases. Codons 129 and 219 play an important role in the susceptibility to sporadic Creutzfeldt‐Jakob disease (CJD). An association between sporadic CJD and the polymorphism (PRNP 1368) in an upstream of PRNP exon 1 has been reported in the British and German populations, but study in the Dutch population has failed to confirm an association.

Polymorphisms at codons 129 and 219 of the prion protein gene (PRNP) are not associated with sporadic Alzheimer's disease in the Korean population

Polymorphisms of prion protein gene (PRNP) at codons 129 and 219 play an important role in the susceptibility to Creutzfeldt‐Jakob disease (CJD). Alzheimers disease (AD) and prion diseases, such as CJD, are both characterized by the accumulation of abnormally folded proteins in the brain. An association between sporadic AD and the PRNP polymorphism at codon 129 has been reported in several studies, but other studies have failed to confirm an association. To investigate whether PRNP polymorphisms are associated with an increased risk for developing sporadic AD in the Korean population, we compared the genotype, allele, and haplotype frequencies of PRNP polymorphisms in 271 sporadic AD patients with those in 236 healthy Koreans. Our study does not show a significant difference in PRNP genotype, allele, and haplotype frequency at codons 129 and 219 between sporadic AD and normal controls. Analyses stratifying by age at disease onset, and gender also failed to reveal any association between these polymorphisms and sporadic AD. These results indicate that these PRNP polymorphisms have no direct influence on the susceptibility to sporadic AD in the Korean population.

Effects of installation depth on survival of an hydroxyapatite-coated Bicon implant for single-tooth restoration.

PURPOSE The present retrospective study evaluated various implant surface factors associated with Bicon implant survival for single-tooth restoration in the healthy individual. PATIENTS AND METHODS A retrospective cohort study design was used. A total of 613 Bicon (Bicon System, Boston, MA) implants (272 patients) were included. Because the use of hydroxyapatite (HA) coating has been controversial, the surface type was chosen according to the patients preference. A total of 308 HA-coated implants and 305 titanium plasma-sprayed (TPS) implants were used. The macroanatomy of both implant types was identical. Patients who had systemic disease, poor quality bone, or removable prosthetics were excluded from the present study. A chart review was conducted to record age, gender, implant diameter, implant length, installation depth, installation location, and the use of bone grafting. Implant failure was recorded, and the data were analyzed using the chi(2) test and logistic regression analysis. RESULTS The installation depth was an important prognostic factor in the HA-coated implants. The failure rate for the HA-coated implants installed at margin level and 2 mm below level was 10.29% and 3.01%, respectively (chi(2) = 6.035, P = .014). The implant length was an important prognostic factor for the TPS-treated implants. The failure rate recorded for the TPS-treated implants installed with a length of less than 10 mm and 10 mm or longer was 15.46% and 2.40%, respectively (chi(2) = 18.414, P < .001). CONCLUSION Many factors can influence the failure rate of TPS and HA-coated Bicon implants. Among these, installation depth played an especially significant role in the success of HA-coated Bicon implants in the present study.

Genetic polymorphism in exon 2 of cathepsin D is not associated with vascular dementia

Jeong B‐H, Lee K‐H, Lee Y‐J, Yun J, Park Y‐J, Kim Y‐H, Cho Y‐S, Choi E‐K, Carp RI, Kim Y‐S. Genetic polymorphism in exon 2 of cathepsin D is not associated with vascular dementia.
Acta Neurol Scand: 2011: 123: 419–423.
© 2010 John Wiley & Sons A/S.

New Bone Formation Between Bare Titanium Surface and Hydroxyapatite Coating by the Aerosol Deposition Technique in the Nasal Mucosal Penetration Model

ObjectiveThe aim of this study was to compare new bone formation with titanium (Ti) surface and hydroxyapatite (HA)-coated titanium surface in mucosal perforation model. Materials and MethodsHA coating to the Ti disc and implant were done by aerosol deposition technique. Alkaline phosphatase assay and cell migration assay were done in Ti and HA surface disc with MG63 cells. For the in vivo test, 5 New Zealand white rabbits were used. Two penetration defects were prepared in the nasal bone. Subsequently, 2 types of implants were installed into the defect (diameter: 3.0 mm, length: 6.0 mm). Approximately 5.0 mm of the fixture’s surface penetrated into the nasal cavity. In the experimental group, HA-coated implants were used. The same design of implants without coating was used in the control group. The animals were sacrificed 8 weeks postoperatively. Subsequently, a histomorphometric analysis was done. ResultsAlkaline phosphatase activity was significantly higher in HA-coated surface than in titanium surface (P < 0.05). In addition, more cells were migrated into the HA-coated surface when compared to Ti surface. In the animal experiments, mean new bone formation was 30.68 ± 14.16% in the experimental group and 6.92 ± 5.12% in the control group (P = 0.001). Mean bone-to-implant contact was 31.71 ± 8.41% in the experimental group and 7.98 ± 5.58% in the control group (P < 0.001). Mean height of the bone regeneration was 3.70 ± 0.76 mm in the experimental group and 1.04 ± 0.67 mm in the control group. The difference between the 2 groups was statistically significant (P < 0.001). ConclusionsHA-coated implants exhibited more bone regeneration in the mucosal penetration model than the uncoated implants.