• Journal of Chest Surgery
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• v.19 no.1
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• pp.92-100
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• 1986

Results of reoperation for tissue valve failure were presented with review of current knowledge. Through January 1986, 19 patients required reoperation: 18 had undergone mitral, 2 aortic, and 1 tricuspid valve. Primary tissue failure was the main cause of tissue valve failure: it occurred in 18 valves [15 mitral, 2 aortic, and 1 tricuspid] at a mean postoperative interval of 54-25 months [range 29-120]. During the same period, 2 patients required reoperation for prosthetic valve endocarditis, 1 for paravalvular leakage. The types of valves failed were 12 lonescu-Shiley valves, 5 Hancock valves, and 1 Carpentier-Edwards valve. All 6 patients younger than 15 years of age at first operation had been implanted with lonescu-Shiley valves and failed after a mean interval of 35 months. In contrast, 11 patients older than 15 years had been implanted with 5 Hancock, 6 lonescu-Shiley, and 1 Carpentier-Edwards valve initially, and eventually failed after mean intervals of 81, 53, 47 months each other. The kinds of valves used at reoperation were 8 lonescu-Shiley, 4 Bjork-Shiley, and 6 St. Jude Medical valves for primary tissue failure cases and 3 lonescu-Shiley valves for the other 3 cases. Overall mortality at reoperation was 10%: 5.6% for primary tissue failure, 50% for prosthetic valve endocarditis. In 15 cases [all mitral] primary tissue failure were caused by calcification associated with or without leaflet destruction or fibrous ingrowth, and in 2 cases [all aortic] caused by cusp perforation and tearing without any evidence of calcification. In conclusion: 1 primary tissue failure is the main cause of reoperation in patients with tissue valve failure; 2. the majority of the failed valves is in mitral position; 3. leaflet calcification is the leading pathology of primary tissue failure; 4, reoperation for tissue valve failure may be a major concern, although the mortality is low; 5. the limited durability of tissue valve suggests its use be restricted to selected cases.

• Korean Journal of Materials Research
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• v.20 no.3
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• pp.155-160
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• 2010

In this study, we investigated primary biocompatibility and osteogenic gene expression of porous granular BCP bone substitutes with or without strontium (Sr) doping. In vitro biocompatibility was investigated on fibroblasts like L929 cells and osteoblasts like MG-63 cells using a cell viability assay (MTT) and one cell morphological observation by SEM, respectively. MTT results showed a cell viability percent of L929 fibroblasts, which was higher in Sr-BCP granules (98-101%) than in the non-doped granules (92-96%, p < 0.05). Osteoblasts like MG-63 cells were also found to proliferate better on Sr-doped BCP granules (01-111%) than on the non-doped ones (92-99%, p < 0.05) using an MTT assay. As compared with pure BCP granules, SEM images of MG-63 cells grown on sample surfaces confirmed that cellular spreading, adhesion and proliferation were facilitated by Sr doping on BCP. Active filopodial growth of MG-63 cells was also observed on Sr-doped BCP granules. The cells on Sr-doped BCP granules were well attached and spread out. Gene expression of osteonectin, osteopontin and osteoprotegrin were also evaluated using reverse transcriptase polymerase chain reaction (RT-PCR), which showed that the mRNA phenotypes of these genes were well maintained and expressed in Sr-doped BCP granules. These results suggest that Sr doping in a porous BCP granule can potentially enhance the biocompatibility and bone ingrowth capability of BCP biomaterials.

• The Korean Journal of Nuclear Medicine
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• v.33 no.6
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• pp.475-483
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• 1999

Purpose: Complete fibrovascular ingrowth within the hydroxyapatite ocular implant is necessary for peg drilling which is performed to Prevent infection and to provide motility to the ocular prosthesis. We compared planar bone scintigraphy and SPECT for the evaluation of the vascularization within hydroxyapatite ocular implants. Materials and Methods: Seventeen patients (M:F: 12:5, mean age; $50.4{\pm}17.5$ years) who had received a coralline hydroxyapatite ocular implant after enucleation surgery were enrolled. Patients underwent Tc-99m MDP planar bone and SPECT imaging by dual head gamma camera after their implant surgery (interval: $197{\pm}81$ days). Uptake on planar and SPECT images was graded visually as less than (grade 1), equal to (grade 2), and greater than (grade 3) nasal bridge activity. Quantitative ratio of implanted to non-implanted intraorbital activity was also measured. Vascularization within hydroxyapatite implants was confirmed by slit lamp examination and ocular movement. Results: All but three patients were considered to be vascularized within hydroxyapatite implants. In visual analysis of planar image and SPECT, grade 1 was noted in 9/18 (50%) and 6/18 (33%), respectively. Grade 2 pattern was 7/18 (39%) and 4/18 (22%), and grade 3 pattern was 2/18 (11%) and 8/18 (44%) respectively. When grade 2 or 3 was considered to be positive for vascularization, the sensitivity of planar and SPECT imaging were 60% (9/15) and 80% (12/15), respectively. In 3 patients with incomplete vascularization, both planar and SPECT showed grade 1 uptake The orbital activity ratios on planar imaging were not significantly different between complete and incomplete vascularization ($1.96{\pm}0.87$ vs $1.17{\pm}0.08$, p>0.05), however, it was significantly higher on SPECT in patients with complete vascularization ($8.44{\pm}5.45$ vs $2.20{\pm}0.87$, p<0.05). Conclusion: In the assessment of fibrovascular ingrowth within ocular implants by Tc-99m MDP bone scintigraphy, SPECT image appears to be more effective than planar scintigraphy.

• Journal of Gastric Cancer
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• v.7 no.2
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• pp.82-87
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• 2007

Purpose: In gastric cancer patients with gastric outlet obstruction, there are several complications such as malnutrition and vomiting. Palliative enteral stenting is a less invasive procedure as compared with a gastrojejunostomy. The aim of this study was to determine whether there was a significant difference between patients that undergone palliative enteral slanting and patients that had received a bypass gastrojejunostomy. Materials and Methods: One hundred patients underwent palliative entering stenting and 3f patients were subjected to a surgical bypass gastrojejunostomy. We reviewed the medical records of the patients with gastric outlet obstruction secondary to far advanced gastric cancer that were diagnosed using a gastrofibroscope, UGI and abdominal CT, and were admitted to our institution between January 2000 and August 2006. The outcome of stent placement for gastric outlet obstruction was compared with palliative gastrojejunostomy during the same period. We excluded patients with recurrent gastric cancer and double cancer from this study. Results: There were significant differences between the group of patients that underwent slanting and the group of patients that received a gastrojejunostomy regarding the age of patients ($67{\pm}12$ vs. $57{\pm}9$, P<0.001) but not between the sex of the patients (M : F, 2 : 1 vs. 2 :1, P=0.637). The most common complication of stenting was tumor ingrowth (16/100, 16%) and the second most common complication was stent migration (14/100). Failure of the procedure occurred in only three patients. Twenty-three patients underwent re-slanting and one patient required open conversion with a gastrojejunostomy. The median time to the first meal was $4{\pm}2$ days in the stent group of patients and $6{\pm}2$ days in the gastrojejunostomy group of patients (P=0.001). The median postoperative hospital stays were 9 days in the stent group of patients and 15 days in the gastrojejunostomy group of patients (P=0.003). The mean survival periods were 11 months in the stent group of patients and 10 months in the gastrojejunostomy group of patients (P=0.937). Conclusion: There were no significant differences In the mean survival rates. An earlier first meal and a shorter hospitalization stay were found in the slanting group of patients compared to the bypass gastrojejunostomy group of patients. However, re-slanting was a concern due to tumor ingrowth and stent migration.

• The Journal of the Petrological Society of Korea
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• v.23 no.3
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• pp.239-247
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• 2014

The (U-Th)/He dating utilizes the production of alpha particles ($^4He$ atoms) during natural radioactive decays of $^{238}U$, $^{235}U$ and $^{232}Th$. (U-Th)/He age can be determined from the abundances of the parent nuclides $^{238}U$, $^{235}U$ and $^{232}Th$ and the radiogenic $^4He$. Because helium is one of the noble gases (non-reactive) with a relatively small radius, it diffuses rapidly in many geological materials, even at low temperatures. Therefore, ingrowth of $^4He$ during radioactive decay competes with diffusive loss at elevated temperatures during the geologic time scale, determining the amount of $^4He$ existing today in natural samples. For example, He diffusion in apatite is known to be very rapid compared to that in most other minerals, causing a significant diffusive loss at ${\sim}80^{\circ}C$ or higher. At ${\sim}40^{\circ}C$, He diffusion in apatite becomes slow enough to preserve most $^4He$ in the sample. Thus, an apatite's (U-Th)/He age represents the timing when the sample passed through the temperature range of $80-40^{\circ}C$. The crustal depth corresponding to this temperature range is called a "partial retention zone." Normal closure temperatures for a typical grain size and cooling rate are ${\sim}60-70^{\circ}C$ for apatite and ${\sim}200^{\circ}C$ for zircon and titanite. Because the apatite He closure temperature is lower than that of most other thermochronometers, it can provide critical constraints on relatively recent or shallow-crustal exhumation histories.

• Analytical Science and Technology
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• v.12 no.5
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• pp.428-435
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• 1999

A method for measuring Rn-222 and Ra-226 in aqueous sample using liquid scintillation counting technique has been studied. The Rn-222 was extracted easily from the water sample (10 mL) by 12 mL of xylene based organic scintillant. After radioactive equilibrium between Rn-222 and its alpha emitting decay products for three hours, the alpha activity from Rn-222 and its decay products were measured in a scintillation vial using the Wallae $1220^{TM}$ Quantulus liquid scintillation counter. Ra-226 concentration in aqueous sample was determined, after isolation of Ra-226 from the sample matrix, by extraction the ingrowth of the Rn-222 and its alpha emitting decay products with xylene based organic scintillant. The optimum pulse-shape analysis (PSA) value was evaluated by the figure of merit (FM) criterion. Minimum detectable activity (MDA) is about 0.14 Bq/L (3.78 pCi) for the region of Rn-222 and its alpha emitting decay products and 0.06 Bq/L (1.63 pCi) for the region of Po-214 respectively, with 200 min, counting time at PSA level 100 in the low-diffusion polyethylene vial and xylene based cocktail solution. Experiment on the optimum sample-cocktail volume ratio, the influence of agitation and the diffusion of radon from vial were carried out.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.20 no.2
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• pp.112-126
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• 1998

In dentistry, bony defects can be formed by cyst, tumor, inflammation, trauma and surgery in maxilla and mandible. If the overlying soft tissue invades and preoccupies the jaw bony defects, regenerated bony tissue same as adjacent bone can not replace whole space of the defects, thus preventing osteogenesis from occurring. Guided bone regeneration(GBR) is based on the prevention of overlying soft tissue from entering the bony defect during the initial healing periods. E-polytetrafluoroethylene(e-PTFE) is one of an effective and widely used barrier membrane for GBR, but it has the disadvantages such as surgical removal and high price. To overcome such disadvantages of e-PTFE, many investigators have proposed various absorbable barrier membranes. Inexpensive oxidized cellulose($Surgicel^{(R)}$) membrane was shown to have potential for use as an absorbable barrier membrane for regenerative procedure and it would not require surgical removal. The purpose of this study is to investigate the absorption periods of oxidized cellulose at the implant site and usefulness as a mechanical barrier, preventing the ingrowth of the overlying soft tissue into the bony defects. Two bony defects were made in each tibia of a dog using drill and one defect covered with oxidized cellulose and the other covered with periosteum directly as control. The experimental animals were sacrificed at 1st-7th, 10th, 14th, 21th, 28th day postoperatively, Inspection of the specimens was done to evaluate gross changes. Specimens were examined histopathologically by hematoxylin-eosin and Masson's trichrome staining under light microscope. The results were as follows : 1. There was no significant differences of inflammatory reaction between the experimental and the control group. 2. The resorption of oxidized cellulose was almost completed within 14th day. 3. Histologically, bone formation in the experimental group was somewhat more than that of the control group at 10th, 14th, 21th and 28th day postoperatively. The bone forming pattern of the experimental group was more regular than that of the control group. 4. There was no evidence of soft tissue invasion into the bony defect in the experimental group. In conclusion, oxidized cellulose membrane might be used as an alternative absorbable barrier membrane to prevent overlying soft tissue invasion into the bony defects.

• Journal of Periodontal and Implant Science
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• v.29 no.2
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• pp.415-433
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• 1999

Implant stability is the key to long-term successful outcome for osseointegrated implants. To evaluate the initial healing response of bone around HA-coated implants without primary bone contact. 21 HA-coated thread type implants(STERI-OSS?) were placed in the femurs of 5 mongrel dogs, about 1-year old. Implants, 8 mm in length and 3.8mm(experimental 1group), 5.0mm(experimental 2group) and 6.0mm(control group) in diameter, were inserted after 3 holes of 6.0mm in diameter and 10mm in depth were prepared in the surgical sites each dog. Implants were supported by only nonresorbable membrane($Teflon^{(R)}$), in order to prevent the ingrowth of upper soft tissue into the gap between bone and implant, and to maintain each implant to be positioned in the center of the drilled hole. 9 implants with different diameters were inserted in 3 dogs for histologic observation, and 12 implants were inserted in 2 dogs for mobility test and removal torque test. Fluorescent dyes were injected for the observation of new bone formation in order of $Terramycin^{(R)}$, Arizarin $Red^{(R)}$, and $Calcein^{(R)}$ at an interval of 2 weeks. 3 dogs were sacrificed for histologic observation at 4, 8, and 12-week after placement. Light microscopy and confocal laser scanning microscopy were used to qualitatively characterize the bone around HA-coated implant. 2 dogs were sacrificed for mobility test($Periotest^{(R)}$, Simens AG, Bensheim, Germany) and removal torque test($Autograph^{(R)}$ AGS-1000D series, Japan) at 8 and 12-week after placement The results were as follows: 1. Histologic observation showed that osseointegration occurred to both control and experimental groups as time lapse, but delayed bone healing was revealed in 3.8mm group (experimental 1group), compared to contrtol group and 5.0mm group (experimental 2group). 2. The mobility test showed that the experimental groups had no distinguishable movement during experimental periods of 8 and 12-week, and there was no difference in mobility depending on the gap between bone and implant, and time lapse. 3. The removal torque forces were increased depended on the gaps decreasing between bone and implant, and time lapse. The results suggest that HA-coated implant without primary bone contact, based on guided bone regeneration could obtain its stability in all experimental groups as time lapse, but bone healing was delayed in experimental group of 3.8mm. And the results suggested that studies on correlationship between mobility test and removal torque test for implant stability would be necessary.

• Journal of Chest Surgery
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• v.29 no.1
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• pp.7-13
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• 1996

The conventional glutaraldehyde (GA) fixation method of tissue valves is considered to be responsible for accelerated valve degeneration. The release of toxic GA from the valve tissue is believed to limit endothelial cell (EC) ingrowth. Removal of toxic GA by reaction with L-glutamic acid and storage in a Paraben solution may offer good EC growth. To investigate the conditions for endothelialization of tissue valves, the growth properties of ECs on the conventionally and alternatively treated pericardial tissue were compared. Conventional preparation included zero-pressure fixation for 72 hours in phosphated-buffered saline (PBS) solution containing 0.5% GA at 4$^{\circ}C$ and storage into PBS containing 0.2% GA(group I). Alternatively treated pericardial tissues were divided into three postfixation treatment groups : (1) storage in PBS solution containing Paraben(group II), (2) treatment with PBS containing 8$^{\circ}C$ L-glutamic acid(PH 7.35) and storage in PBS solution containing Paraben (g oup III), (3) treatment with L-glutamic acid dissolved in distilled water (PH 3.5) (group IV). Pericardial tissue were transferred into the 24-well plate after storage for 4 weeks. ECs were harvested enzymatically from the bovine pulmonary artery and grown to confluence on culture flask surfaces. Detached ECs by trypsin were incubated into the each well of the 24-well plate including test pericardial tissues. Cells were detached by trypsin, 1, 2, 3, 5, 7 days after incubation and counted on the hemacytometer. Cell viability test was performed by frypan-blue exclusion method. Acute cell death in the group I were found even after prolonged washing. The group II showed prolonged cell survival compared with the group I. Both group III and group IV showed better cell growth than group II. There was no statistically significant difference between group III and group IV method in terms of EC growth. This results suggest that treatment by L-glutamic ac id and storage in a Paraben solution be a promising approach for improvement of durability of GA-treated tissue valves.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.23 no.1
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• pp.87-94
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• 2001

The present study was performed to investigate the effect of $HTR^{(R)}$ (Hard Tissue Replacement) on osteogenesis in the mandibular bone defects. Eight adult male white rabbits weighing 2.5 to 3.0kg were used. Four bone defects (8mm in diameter and 4mm in depth) were made at the both mandibular body. In the control group, the right mesial bone defect was filled with blood clot and spontaneously healed. In the DFDB group, the right distal bone defect was filled with xenogenic demineralized freeze-dried bone. In the $HTR^{(R)}$ group, the left mesial bone defect was filled with $HTR^{(R)}$. In the $HTR^{(R)}-membrane$ group, the left distal bone defect was filled with $HTR^{(R)}$ and covered with BioMesh membrane. The rabbits were sacrified at 2,4,6 and 9 weeks after the operation and microscopic examination was performed. Results obtained were as follows: In the control and DFDB groups, inflammatory cells and the fibrous connective tissue existed and the bone growth was slower than $HTR^{(R)}$ group by 6 week, and there was intervention of the soft tissue at 9 week. In the $HTR^{(R)}$ group, bone trabeculi extended between the $HTR^{(R)}$ particles without intervention of inflammatory cells and the connective tissue at 4 and 6 weeks. In addition, extensive osseous ingrowth into the $HTR^{(R)}$ particles was observed at 9 week. Bone formation was more active in the $HTR^{(R)}$ group than the control and DFDB groups. There was not obvious difference in the bone healing rate between the $HTR^{(R)}$ and the $HTR^{(R)}-membrane$ group. These results suggest that the $HTR^{(R)}$ promotes osteogenesis in the bone defects and the $HTR^{(R)}$ group has no difference in comparison with the $HTR^{(R)}-BioMesh^{(R)}$ membrane group in bone healing.