Enhanced guided bone regeneration by controlled tetracycline release from poly(L-lactide) barrier membranes

With the aim of providing effective periodontal therapeutic modality, drug-releasing membranes for guided tissue regeneration (GTR) were developed. As GTR membranes, biodegradable barrier membranes composed of porous poly(L-lactide) (PLLA) films cast on poly(glycolide) (PGA) meshes were fabricated using an in-air drying phase inversion technique. PLLA was dissolved in methylene chloride-ethylacetate mixtures, cast on knitted PGA mesh, and then air-dried. Tetracycline, which is used in periodontal therapy because of its antibacterial activity and tissue regenerating effects, including osteoblast chemotactic effect and anti-collagenolytic activity, was incorporated into the membranes by adding it to PLLA solutions. The guided bone regenerating potential of tetracycline-loaded membranes was evaluated using release kinetics both in vitro and in vivo, biodegradation tests, and cell attachment tests. Homogeneous pores were generated both at the surface and in a sublayer of the membranes. The release kinetics of tetracycline depended mainly upon the hydrophilicity of tetracycline and the porosity of the membrane. The release rate further could be controlled by loaded drug contents. The release of tetracycline was appropriate for maintaining anti-microbial activity and for its tissue-regenerating potential. The membranes retained a proper degradation property, maintaining their mechanical integrity for the barrier function for 4 weeks. Tetracycline-loaded membranes induced increased cell attachment levels compared with those of unloaded membranes. Tetracycline-loaded membranes markedly increased new bone formation in rat calvarial defects and induced bony reunion after 2 weeks of implantation. These results suggest that tetracycline-loaded PLLA membranes potentially enhance guided tissue regenerative efficacy.

Histoclinical analysis of early colorectal cancer

To evaluate the clinicopathologic characteristics of early colorectal cancer (ECC), histopathologic and clinical features of 90 ECC patients who underwent surgical resection (not including the endoscopic polypectomized cases) and 1704 patients with advanced colorectal cancer were analyzed. Smaller size, better histologic differentiation, less lymph node (LN) metastasis, and better clinical outcome were observed in those with ECC than in patients with more advanced lesions. LN metastasis was found in 5 patients with ECC among the 56 patients who underwent bowel resection (8.9%). Tumors with LN metastasis were more frequently associated with deep submucosal invasion, absence of an adenomatous component within the tumor, sessile configuration, and lymphovascular invasion. Tumors showing deep submucosal layer invasion were associated with a more unfavorable histologic grade, lymphovascular invasion, LN metastasis, sessile morphology, and absence of an adenomatous component within the tumor. Recurrence was observed in two patients who underwent local excision for their submucosal cancer. One of the patients was salvaged after bowel resection, but one patient died of distant metastasis. From our data analysis and literature review, extensive submucosal invasion, lymphovascular invasion, sessile configuration, and tumors with no adenomatous component should be considered high risk factors for LN metastasis and recurrence after limited therapy.

Risk of gastric cancer in hereditary nonpolyposis colorectal cancer in Korea

After endometrial cancer, gastric cancer is the second most common extracolonic cancer in cases of hereditary nonpolyposis colorectal cancer (HNPCC), where the relative risk in HNPCC familial members is known to be 4-fold. However, it is not yet clear whether HNPCC families from Korea, an endemic area for gastric cancer, have the same relative risk or whether the incidence of gastric cancer is high enough to justify familial screening. To clarify these questions, we investigated 1011 individuals from 66 Korean HNPCC families (28 families fulfilled the Amsterdam criteria and 38 did not). The overall and age-specific relative risk of gastric cancer in HNPCC families when compared with the background population was calculated. Twenty-five patients with gastric cancer were identified from among 22 HNPCC families. The calculated risk of gastric cancer in patients with HNPCC and their first-degree relatives was 2.1-fold greater than in the general population (95% confidence interval; range, 1.4-3.2). However, the relative risk of gastric cancer in the younger generations was much greater (11.3-fold in the 30s and 5.5-fold in the 40s). Additionally, the relative risk was greater in mutation carrier families than noncarrier families (3.2-fold versus 1.6-fold). This study demonstrates that the risk of gastric cancer in members of HNPCC families in a gastric cancer endemic population, particularly in younger subjects and mutation carrier families, is high enough to justify careful screening.

Novel transcripts of fibroblast growth factor receptor 3 reveal aberrant splicing and activation of cryptic splice sequences in colorectal cancer

A nested reverse transcription-PCR analysis of FGFR3 from human colorectal carcinomas revealed novel mutant transcripts caused by aberrant splicing and activation of cryptic splice sequences. Two aberrantly spliced transcripts were detected with high frequency in 50% of 36 primary tumors and in 60% of 10 human colorectal cancer cell lines. Most transcripts used normal splice sites but skipped or included exons 8 and 9. Two mutant transcripts arose from cryptic splice donor sites in exon 7 that spliced to exon 10. The predicted translation products would exhibit frameshifts and a premature termination codon in exon 10. We propose that dysregulation of mRNA splicing frequently generates an aberrant FGFR3 transcript that may confer a selectable advantage on clones of cells in colorectal tumorigenesis.

Controlled release of platelet-derived growth factor-BB from chondroitin sulfate-chitosan sponge for guided bone regeneration

Platelet-derived growth factor-BB (PDGF-BB) releasing porous chondroitin-4-sulfate (CS)-chitosan sponge was designed with an aim of controlling growth factor delivery in order to improve bone formation. Porous CS-chitosan sponge was fabricated by freeze drying and crosslinking aqueous CS-chitosan solution. PDGF-BB was incorporated into the CS-chitosan sponge by soaking CS-chitosan sponge into the PDGF-BB solution. CS-chitosan sponge retained a porous structure with a 150-200-microm pore diameter that was suitable for cellular migration and osteoid ingrowth. Release rate of PDGF-BB could be controlled by varying the composition of CS in the sponge or initial loading content of PDGF-BB. CS-chitosan sponge induced increased osteoblast migration and proliferation as compared with chitosan sponge alone. Furthermore, the release of PDGF-BB from CS-chitosan sponge significantly enhanced osteoblast proliferation. These results suggest that PDGF-BB-releasing CS-chitosan sponge may be beneficial to enhance bone cell adaptation and regenerative potential when applied in wound sites.

The prevalence and clinical significance of blocking thyrotropin receptor antibodies in untreated hyperthyroid Graves' disease

The goal of this study was to evaluate the clinical significance of the blocking thyrotropin receptor antibodies (TSHRAb) in Graves' disease. The amount of blocking and stimulating TSHRAb were measured in 200 patients with untreated hyperthyroid Graves' disease using several cell lines carrying different TSHR chimera. Stimulating TSHRAb were measured in Chinese hamster ovary (CHO) cells with wild-type human TSHR (CHO-hTSHR) or a TSHR chimera with residues 90-165 (Mc2) or 8-165 (Mc1+2) substituted by equivalent residues of rat luteinizing hormone/chorionic gonadotrophin (LH/CG) receptor or in FRTL-5 cells. Blocking TSHRAb were measured in Mc2 cells. The activities of different TSHRAb were assessed and clinical features were compared to patients who were positive or negative for blocking TSHRAb antibodies. Blocking TSHRAbs were detected in 18.5% of patients (37/200) with hyperthyroid Graves' disease. Patients with blocking antibodies had significantly lower mean stimulating TSHRAb activities than those without blocking antibodies in wild-type CHO-hTSHR cells (301 +/- 179 vs. 446% +/- 537%, p = 0.005). Mean stimulating TSHRAb activities measured by FRTL-5, Mc1+2, or Mc2 cells and mean thyrotropin receptor inhibitor immunoglobulin (TBII) activities were not different between the two groups. The patients with blocking antibodies were not different from those without blocking antibodies in age, gender ratio, initial serum free thyroxine (T4) levels, or goiter size. However, the prevalence of exophthalmos was higher (35.1% vs. 17.5%, p = 0.024) in the patients with blocking antibodies than those without. In summary, the presence of blocking TSHRAb is not rare in patients with hyperthyroid Graves' disease when measured with chimeric receptor expressing cells. Blocking TSHRAb in Graves' sera do not strongly antagonize the action of stimulating TSHRAb in vivo, but could be a major factor responsible for underestimation of stimulating TSHRAb activities measured by CHO-hTSHR. The association of blocking TSHRAb with ophthalmopathy suggests that the TSHRAb repertoire of Graves' patients is different in those who do and who do not have ophthalmopathy.

Population pharmacokinetics of digoxin in Korean patients

AIM

Digoxin possesses a narrow therapeutic index and shows a large inter-patient pharmacokinetic variability. The purpose of this study was to develop a population model for the pharmacokinetics of digoxin in Korean patients.

METHODS

Plasma concentrations of digoxin after multiple administration at varying dosing schedules in Korean patients were used for population modeling. Data analysis was performed with the P-Pharm software. The data were best fitted by a one-compartment model. The effect of demographic and clinical factors like sex, age, weight, disease state, and renal function on the pharmacokinetic parameters of digoxin was investigated.

RESULTS

The study indicated that the clearance of digoxin was influenced by creatinine clearance, while body weight and creatinine clearance were the covariates for its volume of distribution. The population mean estimates for CL and V were 4.4 l/h and 535 l, respectively. Absorption rate constant was lower in females and in the presence of concomitant drug treatment.

CONCLUSION

A population pharmacokinetic model for the digoxin pharmacokinetics in a section of Korean patients was developed. The relationships between the pharmacokinetic parameters and the demographic data and the patient-specific covariates were established.

Polymorphism in the promoter and exon 1 of the cytotoxic T lymphocyte antigen-4 gene associated with autoimmune thyroid disease in Koreans

The objective of this study was to examine the polymorphism in the cytotoxic T lymphocyte antigen-4 (CTLA-4) gene and its relationship with autoimmune thyroid disease in Koreans. Polymorphism in the promoter and exon 1 of CTLA-4, clinical symptoms of disease and thyrotropin receptor antibody (TSHRAb) characteristics were analyzed. Polymorphism was detected using restriction fragment length polymorphism and polymerase chain reaction amplification of genomic DNA. All subjects were Korean (97 Graves' disease, 110 Hashimoto's thyroiditis, and 199 normal controls). Graves' patients had significantly more G allele in exon 1 and C allele in the promoter than controls. When the exon 1 genotype was GG, the frequency of CC genotype in the promoter was higher. Allele frequencies in CTLA-4 did not differ from controls in patients with Hashimoto's thyroiditis. In Graves' patients, there were significant differences between genotypic groups in serum triiodothyronine (T3) levels and the presence of ophthalmopathy. However, TSHRAbs and other clinical characteristics were not significantly different. In conclusion, the CTLA-4 G allele in exon 1 and C allele in the promoter may confer genetic susceptibility to Graves' disease in Koreans. These two polymorphisms are additional and dependent genetic risk markers that help to characterize risk alleles within CTLA-4 gene.

Effect of temperature on the breakthrough of a charcoal tube during vinyl chloride monomer sampling

This study evaluated the effects of temperature on breakthrough of two standard collection media at various concentrations during vinyl chloride monomer (VCM) sampling. The National Institute for Occupational Safety and Health (NIOSH) and Occupational Safety and Health Administration (OSHA) methods were evaluated. To determine whether breakthrough of VCM would occur at the extremes of exposure and temperature that might be encountered in some workplaces, air samples containing 4 ppm (10.24 mg/m3), 8 ppm (20.45 mg/m3), 16 ppm (40.98 mg/m3), and 32 ppm (81.80 mg/m3) of VCM were collected at temperatures of 4, 22, and 40 degrees C. Five liters of air was sampled at the rate of 0.05 L/min for 100 min using the activated charcoal tube recommended by NIOSH. A second tube was added to the sampling train to collect any VCM that might not have been absorbed in the first tube. To collect VCM air samples by the OSHA method, two carbon molecular sieve tubes were connected serially and 3 L of air was sampled at the rate of 0.05 L/min for 60 min. A gas chromatograph with a flame ionization detector and ultra 2 capillary column was used to analyze VCM. Significant breakthrough was found when sampling at higher temperatures with the NIOSH method. No breakthrough was found when samples were collected using the OSHA media at different temperatures and concentrations. Therefore, under hot ambient conditions (>22 degrees C), the possibility of breakthrough should be considered when sampling VCM by the NIOSH method.

Screening method for detecting staphylococci with reduced susceptibility to teicoplanin

The incidence of infections caused by staphylococci with decreased susceptibility to teicoplanin (MIC>/=8 microg/ml) is increasing, but the disk diffusion test has difficulty detecting this low level of resistance. In addition, detection is complicated because of the heterogeneous phenotypes for teicoplanin. In this study, we evaluated an agar screening method to detect staphylococci with decreased susceptibility to teicoplanin or heterogeneous resistance. First, to investigate the inoculum density and teicoplanin concentration of screening agar, we used 10(5) and 10(6) CFU/ml and Mueller-Hinton agars supplemented with 6 and 8 microg of teicoplanin/ml to test 39 genetically distinct staphylococcal strains (15 strains with teicoplanin MICs>/=8 microg/ml and 24 strains with teicoplanin MICs</=4 microg/ml). On the basis of the results obtained, a final inoculum of 10(6) CFU/spot and a teicoplanin concentration of 8 microg/ml were selected. By this screening method, all strains having teicoplanin MICs>/=8 microg/ml or showing heteroresistance could be detected. These findings indicate that the method can be used as a reliable screening method for detecting staphylococci with reduced susceptibility to teicoplanin.

Germline mutations of the STK11 gene in Korean Peutz-Jeghers syndrome patients

Peutz-Jeghers syndrome (PJS) is an autosomal dominantly inherited disease characterized by hamartomatous gastrointestinal polyps and mucocutaneous pigmentation, with an increased risk for various neoplasms, including gastrointestinal cancer. Recently, the PJS gene encoding the serine/threonine kinase STK11 (also named LKB1) was mapped to chromosome 19p13.3, and germline mutations were identified in PJS patients. We screened a total of ten Korean PJS patients (nine sporadic cases and one familial case including two patients) to investigate the germline mutations of the STK11 gene. By polymerase chain reaction-single-strand conformation polymorphism and DNA sequencing analysis, three kinds of mis-sense mutation and a frame-shift mutation were identified: codon 232 (TCC to CCC) in exon 5, codon 256 (GAA to GCA) in exon 6, codon 324 (CCG to CTG) in exon 8, and a guanine insertion at codon 342 resulting in a premature stop codon in exon 8. These mis-sense variants were not detected in 100 control DNA samples. Furthermore, we found an intronic mutation at the dinucleotide sequence of a splice-acceptor site: a one base substitution from AG to CG in intron 1, which may cause aberrant splicing. Most reported germline mutations of the STK11 gene in PJS patients were frame-shift or non-sense mutations resulting in truncated proteins. Together, these findings indicate that germline mis-sense mutations of the STK11 gene are found in PJS patients in addition to truncating mutations. The effects of these mutations on protein function require further examination. In summary, we found germline mutations of the STK11 gene in five out of ten Korean PJS patients.

Tissue engineered bone formation using chitosan/tricalcium phosphate sponges

BACKGROUND

Chitosan is a biodegradable natural polymer that has been shown to improve wound healing. This study aimed to develop chitosan/tricalcium phosphate (TCP) sponges as tissue engineering scaffolds for bone formation by three-dimensional osteoblast culture.

METHODS

The sponges were prepared by freeze-drying and cross-linking a mixture of chitosan solution with TCP. Fetal rat calvarial osteoblastic cells were isolated, cultured, and seeded into the sponges. The cell-sponge constructs were cultured for 56 days. Cell proliferation, alkaline phosphatase (ALPase) activity, and calcium deposition in the cell-sponge constructs were measured at 1, 7, 14, 28, and 56 days. Histologic examination was performed with light microscopy and scanning electron microscopy.

RESULTS

Chitosan/TCP sponges supported the proliferation of osteoblastic cells as well as their differentiation as indicated by high ALPase activities and deposition of mineralized matrices by the cells. Light and scanning electron microscopic examination indicated that seeded osteoblastic cells were well attached to sponge matrices and proliferated in a multi-layer fashion. Small bone-like spicules were observed on the sponge matrix at 14 days. Seeded cells appeared to be embedded in the newly formed tissue matrix, which is characteristic of the osteoblast differentiation and their progression into osteocytic cells. The amount of mineralized tissue formed in the sponge at 56 days was significant.

CONCLUSIONS

These results suggest that the chitosan/TCP sponge is a feasible tool as a scaffolding material to grow osteoblast in a three-dimensional structure for transplantation into a site for bone regeneration.

The bone regenerative effect of platelet-derived growth factor-BB delivered with a chitosan/tricalcium phosphate sponge carrier

BACKGROUND

In order to achieve optimal effects, growth factors including platelet-derived growth factor (PDGF) should be delivered with a biodegradable carrier that will release therapeutic concentrations over a sufficient length of time. The purpose of this study was to evaluate the bone regenerative effect of PDGF-BB delivered with a chitosan/tricalcium phosphate (TCP) sponge carrier in a rat calvarial defect model.

METHODS

The PDGF-BB-loaded chitosan/TCP sponge carrier was fabricated by freeze-drying a mixture of chitosan solution and TCP powder and soaking in a PDGF-BB solution. The release kinetics of PDGF-BB loaded onto the sponge were measured in vitro with 125I-labeled PDGF-BB. Chitosan/TCP sponges with and without PDGF-BB were implanted into 8 mm calvarial defects in rats. Rats were sacrificed at 2 and 4 weeks following implantation, and histologic and histomorphometrical examinations were performed.

RESULTS

In vitro evaluation demonstrated that an effective therapeutic concentration of PDGF-BB following a high initial burst release was maintained throughout the examination period. In the histologic examination, the chitosan/TCP sponge carrier promoted osseous healing of the rat calvarial defects as compared to controls. The addition of PDGF-BB to the carrier further enhanced bone regeneration. Evidence of the degraded sponge matrix was observed mingled within the newly formed bone without connective tissue encapsulation.

CONCLUSIONS

The results of this study support the use of chitosan/TCP sponges as a delivery system for growth factors and demonstrate that PDGF-BB loaded onto chitosan/TCP sponge carriers has an osteogenic effect on bone regeneration in vivo.

Clinical characteristics of Peutz-Jeghers syndrome in Korean polyposis patients

Peutz-Jeghers syndrome is an autosomal dominant inherited disorder characterized by hamartomatous polyps in the small bowel and mucocutaneous pigmentation. Patients with Peutz-Jeghers syndrome often present as surgical emergencies with complications of the polyps, such as intussusception, bowel obstruction, and bleeding. Recently an increased risk of malignancies has also been reported. This study was initiated to determine the clinical features of Peutz-Jeghers syndrome in Korean patients, with special attention to the development of malignancies. Thirty patients with Peutz-Jeghers syndrome were investigated; their median age was 23.5 years, and symptoms appeared at a median age of 12.5 years. Family history was positive in one-half of cases, and mucocutaneous pigmentation was observed in almost all patients (93%). The jejunoileum was the most frequent site of the polyps, and there were generally 10-100 polyps. Multiple laparotomies were performed in a substantial portion of the patients, due mainly to polyp-induced bowel obstruction, and the surgical interventions were begun at a relatively young age (average 21.4 years). Four cases of small-bowel cancer and one case of breast cancer were detected in probands, at a relatively young age (mean 36 years). Cancers of the small bowel, stomach, colon, breast and cervix were diagnosed in the first relatives of the probands. Close follow-up from an early age should thus be performed in patients with Peutz-Jeghers syndrome as they are at high risk of surgical emergency and development of malignancy.

Mutational analysis of the transforming growth factor beta receptor type II gene in hereditary nonpolyposis colorectal cancer and early-onset colorectal cancer patients

Somatic mutations in the transforming growth factor beta receptor type II (TGF-beta RII) gene have been observed in various human cancers showing microsatellite instability. Most of the mutations observed were additions or deletions of the mononucleotide repeat sequence present in TGF-beta RII coding region, suggesting that the TGF-beta RII may be a target gene of genomic instability in tumorigenesis. Recently, we reported germ-line frameshift mutations in the mononucleotide repeat sequence of the hMSH6 gene, which is believed to be one of the target genes of genomic instability in tumorigenesis, suggesting the possibility of germ-line mutation in mononucleotide repeat sequences. Moreover, one case of germ-line mutation in the TGF-beta RII gene was identified in a hereditary nonpolyposis colorectal cancer (HNPCC) kindred, indicating the involvement of TGF-beta RII inactivation in tumorigenesis of HNPCC. However, germ-line mutation analysis of all of the coding sequences and the mononucleotide repeat sequence of the TGF-beta RII in HNPCC patients has not yet been fully elucidated. Therefore, to further investigate the presence of germ-line mutations, we screened all of the coding region sequences and mononucleotide repeat sequence of TGF-beta RII from 35 HNPCC, 44 suspected HNPCC, and 45 sporadic early-onset colorectal cancer patients. However, no pathogenic mutations other than silent mutations, introgenic mutation, and polymorphisms were identified. Two silent mutations at codons 309 (ACG to ACA) and 340 (CAT to CAC) in the kinase domain located in exon 4 were detected. A 1-bp cytidine deletion was observed 6 bases from the 3' end of intron. Two polymorphisms were identified at codon 389 (AAC to AAT) and at the fourth-to-last base in intron 3. The polymorphism at codon 389 was more frequent in HNPCC (20%; 7 of 35) and suspected HNPCC patients (18%; 8 of 44) than in nonmalignant control group (10%; 5 of 50). Moreover, the frequency was significantly higher in early-onset colorectal cancer patients (31%; 14 of 45). This is the first report of a different frequency of polymorphism in HNPCC, suspected HNPCC, early-onset colorectal cancer patients, and healthy normal individuals. This result suggests that: (a) germ-line mutation of the TGF-beta RII gene may be a rare event during tumorigenesis in HNPCC and sporadic early-onset colorectal cancer; (b) the mononucleotide repeat sequence of the TGF-beta RII gene is an apparent target of genomic instability but not of germ-line mutation; and (c) the polymorphism of codon 389 (AAC to AAT) is frequent, especially in early-onset colorectal cancer patients, in which it is more frequent than in control group.

Comparison of glucose tolerance categories in the Korean population according to World Health Organization and American Diabetes Association diagnostic criteria

OBJECTIVES

To compare the prevalence and metabolic profiles of glucose tolerance categories according to World Health Organization(WHO) and 1997 American Diabetes Association(ADA) fasting criteria for the diagnosis of diabetes mellitus and impaired glucose metabolism in the Korean population.

METHODS

2251 subjects without previous history of diabetes, who participated in the Yonchon diabetes epidemiology survey in 1993, were classified according to both criteria. The prevalence of glucose tolerance categories and the agreement across all categories of glucose tolerance were calculated. Metabolic characteristics of different glucose tolerance categories were compared.

RESULTS

The prevalence of diabetes and impaired fasting glucose(IFG) according to ADA fasting criteria was similar to those of diabetes and impaired glucose tolerance(IGT) according to WHO criteria, respectively. However, 35.5% of the subjects who were diagnosed as diabetes by WHO criteria were reclassified as either IFG or normal fasting glucose (NFG), and 38.5% of diabetic patients according to ADA fasting criteria were IGT or normal glucose tolerance (NGT) by WHO criteria. Only 31.3% of IGT subjects remained as IFG and 62.1% were reclassified as NFG. Similarly, 69.4% of IFG subjects were NGT by WHO criteria. The agreement between the two criteria was poor (K = 0.31). Discordant diabetes groups had higher WHR, systolic and diastolic blood pressure, cholesterol and triglyceride levels than concordant non-diabetes group. Non-diabetes(WHO)/diabetes(ADA) group had higher WHR than diabetes (WHO)/non-diabetes(ADA) group. There were no differences in other metabolic characteristics between the two discordant diabetes groups. IGT/NFG and NGT/IFG group showed higher BMI, WHR, systolic and diastolic blood pressure, cholesterol and triglyceride levels than NGT/NFG group. Metabolic characteristics of IGT/NFG group were not different from those of NGT/IFG group except IGT/NFG subjects were older than NGT/IFG subjects.

CONCLUSION

The agreement between WHO and ADA fasting criteria was poor. ADA fasting criteria can detect new diabetic patients and subjects with impaired glucose metabolism who are not classified as diabetes or IGT by WHO criteria. However, a substantial number of subjects, who may have increased cardiovascular risk and/or increased risk for the development of diabetes and its complication, will be missed when using ADA fasting criteria.

Platelet derived growth factor releasing chitosan sponge for periodontal bone regeneration

With an aim of improving bone regeneration, chitosan sponge containing platelet-derived growth factor-BB (PDGF-BB) were developed. For fabrication of chitosan sponge, chitosan solution was freeze-dried, crosslinked and freeze-dried again. PDGF-BB was incorporated into the chitosan sponge by soaking chitosan sponge into the PDGF-BB solution. Release kinetics of PDGF-BB, cell attachment, proliferation capacity and bony regenerative potentials of PDGF-BB-loaded chitosan sponge were investigated. Prepared chitosan sponge retained porous structure with 100 microm pore diameter that was suitable for cellular migration and growth. Release rate of PDGF-BB could be controlled by varying initial loading content of PDGF-BB to obtain optimal therapeutic efficacy. PDGF-BB-loaded chitosan sponge induced significantly high cell attachment and proliferation level, which indicated good cellular adaptability. PDGF-BB-loaded chitosan sponge demonstrated marked increase in new bone formation and rapid calcification. Degradation of the chitosan sponge was proceeded at defect site and subsequently replaced with new bone. Histomorphometric analysis confirmed that PDGF-BB-loaded chitosan sponge significantly induced new bone formation. These results suggested that chitosan sponge and PDGF-BB-loaded chitosan sponge may be beneficial to enhance periodontal bone regeneration.

Behcet's disease associated with myelodysplastic syndrome: a case report

A rare case of Behcet's disease associated with myelodysplastic syndrome (MDS) is described. A 50-year-old Korean female suffering recurrent oral ulcer, genital ulcer, fatigue, arthralgia in both knees and fever was diagnosed as Behcet's disease. The findings of bone marrow aspirates were consistent with refractory anemia, a subtype of myelodysplastic syndrome. Chromosomal analysis of bone marrow cells revealed 46,XX,-8,-20,+der(8)t(8;20)(p23;p10),+der(8) t(8;20)(p23;q10)[30]. The chromosomal changes found in this patient were different from those of previous reports, which mostly revealed trisomy 8. If anemia, low reticulocyte count and dyspoietic cells are sustained in Behcet's disease, physicians should be alert to the possibility of MDS with aberration in chromosome 8 and perform a bone marrow study for the proper diagnosis and treatment of the disease. We presented a case of Behcet's disease associated with MDS, which is the first Korean case.

Mini-detachable snare ligation for the treatment of esophageal varices

BACKGROUND

We manufactured and studied the usefulness of a newly designed mini-detachable snare in the treatment of esophageal varices. The use of a multiple rubber band ligator, although generally effective and well tolerated, has certain limitations, including high cost, reduced visual field, and inadvertent band release.

METHODS

We performed a prospective randomized controlled trial of the use of mini-detachable snare ligation vs. multiple band ligation in patients with recent or active esophageal variceal bleeding. The outcomes assessed were immediate hemostasis and rates of recurrent bleeding, eradication, and recurrence.

RESULTS

From March 1997 to October 1998, 103 patients were entered into this trial; 46 underwent mini-detachable snare ligations and 57 multiple band ligations. Among patients with active bleeding, hemostasis was achieved in 6 of 7 (86%) in the mini-detachable snare ligation group and 11 of 13 (85%) in multiple band ligation group. Recurrent bleeding after initial treatment occurred in 2 of 46 (5.5%) in the mini-detachable snare ligation group and 3 of 57 (5.3%) in the multiple band ligation group. Esophageal varices were eradicated or reduced to grade I in 4.8 +/- 2.1 and 4.5 +/- 1.9 sessions in the mini-detachable snare ligation group and multiple band ligation group, respectively. The recurrence rate was 5 of 46 (11%) and 6 of 57 (11%) in the mini-detachable snare ligation group and multiple band ligation group during a follow-up period of 6 and 16 months, respectively. No serious complication occurred in either group.

CONCLUSION

The mini-detachable snare is a new device that provides safe and effective treatment for esophageal varices that is comparable to multiple band ligation.

Gene-environment interaction in hereditary nonpolyposis colorectal cancer with implications for diagnosis and genetic testing

Hereditary nonpolyposis colorectal cancer (Lynch syndrome) is an autosomal dominant disease caused by mutations in the mismatch repair genes in particular in MLH1, MSH2 and MSH6. The disease is characterized by the development of colorectal, endometrial cancer and several other cancers. There is evidence that the clinical expression of the disease varies from one country to another. This variation might affect not only the application of criteria proposed to identify families but also clinical risk factors reported to predict the outcome of genetic testing. Data on site of the cancer, age at diagnosis and pathology were collected from 155 families with suspected HNPCC known at the Korean and Dutch HNPCC registries. DGGE, SSCP and DNA-sequencing were performed to identify MSH2, MLH1 and MSH6 mutations. A total of 33 Korean and 42 Dutch families met the clinical criteria for HNPCC. Germline mutations in the MMR-genes were found in 23 Korean and 24 Dutch families. In families that met the Amsterdam criteria, and also in those associated with MLH1 mutations, more cancers of the stomach and pancreas were observed in the Korean families than in the Dutch HNPCC families; in relative terms, the incidence of cancers of the endometrium in the Korean families was lower. Multivariate analysis showed that an early age at diagnosis, and the occurrence of pancreatic cancer were independent predictive factors of germline mutations in MLH1, MSH2 and MSH6 in the Korean subset of families.

Gene-environment interaction in hereditary nonpolyposis colorectal cancer with implications for diagnosis and genetic testing

Hereditary nonpolyposis colorectal cancer (Lynch syndrome) is an autosomal dominant disease caused by mutations in the mismatch repair genes in particular in MLH1, MSH2 and MSH6. The disease is characterized by the development of colorectal, endometrial cancer and several other cancers. There is evidence that the clinical expression of the disease varies from one country to another. This variation might affect not only the application of criteria proposed to identify families but also clinical risk factors reported to predict the outcome of genetic testing. Data on site of the cancer, age at diagnosis and pathology were collected from 155 families with suspected HNPCC known at the Korean and Dutch HNPCC registries. DGGE, SSCP and DNA-sequencing were performed to identify MSH2, MLH1 and MSH6 mutations. A total of 33 Korean and 42 Dutch families met the clinical criteria for HNPCC. Germline mutations in the MMR-genes were found in 23 Korean and 24 Dutch families. In families that met the Amsterdam criteria, and also in those associated with MLH1 mutations, more cancers of the stomach and pancreas were observed in the Korean families than in the Dutch HNPCC families; in relative terms, the incidence of cancers of the endometrium in the Korean families was lower. Multivariate analysis showed that an early age at diagnosis, and the occurrence of pancreatic cancer were independent predictive factors of germline mutations in MLH1, MSH2 and MSH6 in the Korean subset of families.

Reproducibility of the cortisol response to stimulation with the low dose (1 microg) of ACTH

OBJECTIVE

Previous studies have shown that the rapid ACTH stimulation test using a low dose of 1 microg is more sensitive than that using 250 microg ACTH for detecting subtle cases of adrenal insufficiency. However, there are controversies for the reproducibility of the 1 microg-test. To evaluate the reproducibility of the 1 microg-test, we assessed both day-to-day and diurnal variations of cortisol responses to 1 microg ACTH injection. In addition, optimum sampling time for the 1 microg-test was also determined.

SUBJECTS

AND DESIGN Eight healthy volunteers and five patients with secondary adrenal insufficiency were recruited. Healthy subjects were given 1 microg ACTH 3 times in the morning (0800 h) and 2 times in the afternoon (1600 h). Patients with adrenal insufficiency had 2-tests in the morning and 2 in the afternoon. Serum cortisol levels were measured every 10 minutes for 1 h after the injection.

RESULTS

In healthy subjects, basal and peak serum cortisol levels were significantly higher in the morning (P < 0.05), whereas maximum cortisol increments were higher in the afternoon (P < 0.001). In patients with adrenal insufficiency, basal and peak serum cortisol levels in the morning were not different from corresponding values in the afternoon. Intra-individual coefficient of variation (CV) of peak serum cortisol response to 1 microg ACTH ranged from 3.0 to 16.4% in healthy subjects and 10.0-34. 4% in patients. Also, there was a significant correlation between peak morning or afternoon cortisol levels after 1 microg ACTH injection given in different days in both healthy subjects and patients. Twenty-six of the 40 studies in healthy subjects showed peak response at 20 minutes, while nine showed it at 30 minutes Using the data acquired at 20 and 30 minutes, all 40 studies in healthy subjects showed normal results while none of 20 studies in patients was normal.

CONCLUSIONS

We conclude that the cortisol response to 1 microg ACTH stimulation was reproducible in both healthy subjects and patients with secondary adrenal insufficiency. In order to assess adrenal function more accurately with the 1 microg ACTH stimulation test, serum cortisol should be measured before and 20 and 30 minutes after ACTH injection.

Phenotypic characteristics of Enterococcus faecium variants confirmed by intergenic ribosomal polymerase chain reaction and E. faecium polymerase chain reaction

Enterococcus faecium has recently emerged as a serious nosocomial pathogen. The emergence of multiple antimicrobial agent-resistant E. faecium has been remarkable; with its strains it is one of the most phenotypically heterogeneous of all enterococcal species. About 15% of enterococcal strains isolated from human clinical specimens were found to have atypical biochemical characteristics. In order to determine if these strains were E. faecium variants, intergenic ribosomal polymerase chain reaction (ITS-PCR) and E. faecium PCR (EfPCR) were performed in 45 atypical strains, and the two PCR results were used to analyze phenotypic characteristics of the strains. As many as 60% (27/45) of the atypical strains were identified as E. faecium. Thus, it is concluded that if an enterococcal strain shows positive reaction to arabinose, arginine, and ribose and negative reaction to methyl-alpha-D-glucopyranoside and pigment, it should be identified as E. faecium.

Prognostic factors in 2230 Korean colorectal cancer patients: analysis of consecutively operated cases

To define the prognostic factors in Korean colorectal cancer patients, univariate and multivariate analysis were performed on data from 2230 consecutive patients who underwent resection for colorectal cancer at the Seoul National University Hospital. The prognostic variables used for the analysis included patient's age, gender, bowel obstruction, bleeding, symptom duration, preoperative leukocyte count, preoperative serum carcinoembryonic antigen (CEA) level, Dukes' stage, tumor location, tumor size, depth of bowel wall invasion, number of lymph node metastases, histologic differentiation, and gross morphology of tumor. The overall 5-year survival rate was 62%. In the univariate analysis, all the factors except sex, symptom duration, and tumor size were associated with prognosis. Among the factors significant in the univariate analysis, Dukes' stage (p < 0.001), number of lymph node metastasis (p < 0.001), CEA level (p < 0.001), tumor location (p = 0.003), gross morphology of tumor (p = 0.017), and depth of bowel wall invasion (p = 0.031) were significant in the multivariate analysis. Several differences in prognostic factors between colon cancer and rectal cancer were observed. In the multivariate analysis, gross tumor morphology was significant only for colon cancer, and histologic differentiation was significant only for rectal cancer. Lymph node metastasis was an independent prognostic variable for both colon and rectal cancer, but its significance was more prominent for rectal cancer. Although Dukes' stage is the most reliable prognostic predictor, this study shows that other factors (preoperative CEA level, gross morphology of tumor, location of tumor, nodal status) also provide important information for the outcome of the patient.

Gas chromatographic organic acid profiling analysis of brandies and whiskeys for pattern recognition analysis

An efficient gas chromatographic profiling and pattern recognition method is described for brandy and whiskey samples according to their organic acid contents. It involves solid-phase extraction of organic acids using Chromosorb P with subsequent conversion to stable tert-butyldimethylsilyl derivatives for the direct analysis by capillary column gas chromatography and gas chromatography-mass spectrometry. A total of 12 organic acids were reproducibly identified in liquor samples (1 mL). When the GC profiles were simplified to their retention index spectra, characteristic patterns were obtained for each liquor sample as well as for each group average. Stepwise discriminant analysis provided star symbols characteristic for each liquor sample and group average. As expected, canonical discriminant analysis correctly classified 23 liquor samples studied into two groups of either brandy or whiskey.

Shear-induced tyrosine phosphorylation in endothelial cells requires Rac1-dependent production of ROS

The shear-induced intracellular signal transduction pathway in vascular endothelial cells involves tyrosine phosphorylation and activation of mitogen-activated protein (MAP) kinase, which may be responsible for the sustained release of nitric oxide. MAP kinase is known to be activated by reactive oxygen species (ROS), such as H2O2, in several cell types. ROS production in ligand-stimulated nonphagocytic cells appears to require the participation of a Ras-related small GTP-binding protein, Rac1. We hypothesized that Rac1 might serve as a mediator for the effect of shear stress on MAP kinase activation. Exposure of bovine aortic endothelial cells to laminar shear stress of 20 dyn/cm2 for 5-30 min stimulated total cellular and cytosolic tyrosine phosphorylation as well as tyrosine phosphorylation of MAP kinase. Treating endothelial cells with the antioxidants N-acetylcysteine and pyrrolidine dithiocarbamate inhibited in a dose-dependent manner the shear-stimulated increase in total cytosolic and, specifically, MAP kinase tyrosine phosphorylation. Hence, the onset of shear stress caused an enhanced generation of intracellular ROS, as evidenced by an oxidized protein detection kit, which were required for the shear-induced total cellular and MAP kinase tyrosine phosphorylation. Total cellular and MAP kinase tyrosine phosphorylation was completely blocked in sheared bovine aortic endothelial cells expressing a dominant negative Rac1 gene product (N17rac1). We concluded that the GTPase Rac1 mediates the shear-induced tyrosine phosphorylation of MAP kinase via regulation of the flow-dependent redox changes in endothelial cells in physiological and pathological circumstances.

Experience of 1446 rectal cancer patients in Korea and analysis of prognostic factors

In order to investigate the changing pattern of rectal cancers in Korea and to identify prognostic factors, we investigated the case histories of 1446 rectal cancer patients who had received surgical treatment. During the study period there were trends toward a decrease in the ratio of rectal cancer to colon cancer, earlier detection (more Dukes' stages A and B and fewer C), a decrease in the number of abdominoperineal resections, and an increase in the number of sphincter-preserving operations. Univariate analysis of prognostic factors showed that gender, obstruction symptoms, preoperative serum carcinoembryonic antigen (CEA) level, tumor size, depth of bowel wall invasion, lymph node metastases (presence and number), tumor differentiation, operative method, and date of operation were significant, but age, symptom duration, and tumor location were not. The use of sphincter-saving operations did not adversely affect the clinical outcome. Multivariate analysis showed lymph node metastasis factor to be the most significant factor (P < 0.001); the depth of bowel wall invasion, differentiation, CEA level, and date of operation were also significant (0.001 < P < 0.05). This study shows that although anatomical extent of disease (depth of invasion and lymph node metastasis) is the most reliable prognostic predictor in rectal cancer, other factors such as preoperative CEA level and tumor differentiation also provide important information on the outcome and use of an anal-preserving operation does not adversely affect the patient survival.

Development of a new photoinitiation system for dental light-cure composite resins

OBJECTIVES

The purpose of this study is to explore the synergistic effect of combining camphorquinone (CQ) with 1-phenyl-1,2-propanedione (PPD) as a new photoinitiator.

METHODS

A BisGMA, UDMA, TEGDMA monomer mixture was made light-curing with CQ and/or PPD plus 0.2 wt.% N,N-cyanoethyl-methylaniline (CEMA). Seventeen groups, three specimens each, were tested in which the concentrations of PPD and CQ were varied. The effect of photosensitizer type (CQ or PPD) and ratio (PPD/CQ) on degree of conversion (DC) was investigated using FTIR spectrophotometry. The results were analyzed by ANOVA and Student-Newman-Keuls' multiple range comparison. The absorption spectra of PPD and CQ were recorded by UV-Vis spectrophotometry. A blind color comparison of specimens containing combinations of the two photosensitizers was also undertaken.

RESULTS

Alone, PPD induces a DC which is not significantly different from that of CQ alone. In combination, CQ + PPD produces a DC that generally exceeds that produced by the same concentration of either used alone. The maximum DC occurs between PPD/CQ = 1:1 and 1:4. At total photosensitizer concentrations above 1.8 wt.%, DC is increased by PPD but depressed by CQ, which is evidence that different mechanisms are involved. PPD (lambda max approximately 410 nm) and CQ (lambda max approximately 468 nm) have different wavelength absorption ranges, resulting in a perceptibly lighter shade of yellow for PPD.

SIGNIFICANCE

1-phenyl-1,2-propanedione is a photosensitizer of potential value in reducing color problems associated with visible light cured dental resins. In combination with camphorquinone, it acts synergistically to produce a more efficient photoinitiation reaction.

Peutz-Jeghers syndrome: a new understanding

Peutz-Jeghers syndrome is an autosomal dominant inherited disorder characterized by hamartomatous polyps in the small bowel and mucocutaneous pigmentation. Patients with Peutz-Jeghers syndrome often present as surgical emergencies with complications of the polyps, such as intussusception, bowel obstruction and bleeding. Furthermore, repeated operations may be needed in some patients, which may result in short bowel syndrome. Although early reports did not demonstrate a predisposition to cancer in patients with this syndrome, more recent studies have described an increased risk for both gastrointestinal and extra-gastrointestinal cancers. Women with the Peutz-Jeghers syndrome have the extremely high risk for breast and gynecologic cancer. Recently, Peutz-Jeghers syndrome susceptibility gene, encoding the serine threonine kinase STK11 (also called LKB1), was identified in families with Peutz-Jeghers syndrome. The identifications of germline mutations in families with Peutz-Jeghers syndrome could be a turning point in the management of Peutz-Jeghers syndrome.

Investigation of Coordinational Properties of Europium(III) Complexes with Picolinic Acid Using Eu(III) Excitation Spectroscopy

The 7F0 --> 5D0 excitation spectra of Eu(III) complexed with picolinic acid were investigated using Eu(III) excitation spectroscopy. Six overlapping peaks are seen in the excitation spectra, indicating the formation of six species. The structures of the six species are proposed here and described in terms of both coordination by carboxylate and N-chelation. Copyright 1999 Academic Press.

[Medical education in Je Joon Won]

Medical education in Je Joong Won was proposed and initiated by Dr. HN Allen. In his proposal of building a new hospital, submitted to the king in 1885, he expressed his wish to teach Western medicine to young Koreans at the hospital. The king welcomed his proposal and the plan was soon realized. Je Joon Won, the first modern hospital in Korea, opened on April 10th, 1885. The following year, on March 29th, Dr. Allen began medical school attached to the hospital. Many applicants were recruited by the government and 16 students were selected through the entrance examination. At first, they were taught English and finally 12 students out of them were selected after three months of teaching. The selected students were taught arithmetic, physics, chemistry, anatomy and physiology. The medical education at this period cannot be evaluated entirely successful since none of the 12 students was presumed to have worked as a practitioner.

Korean Nationwide Surveillance of Antimicrobial Resistance of bacteria in 1997

Antimicrobial-resistant bacteria are known to be prevalent in tertiary-care hospitals in Korea. Twenty hospitals participated to this surveillance to determine the nationwide prevalence of resistance bacteria in 1997. Seven per cent and 26% of Escherichia coli and Klebsiella pneumoniae were resistant to 3rd-generation cephalosporin. Increased resistance rates, 19% of Acinetobacter baumannii to ampicillin/sulbactam, and 17% of Pseudomonas aeruginoa to imipenem, were noted. The resistance rate to fluoroquinolone rose to 24% in E. coli, 56% in A. baumannii and 42% in P. aeruginosa. Mean resistance rates were similar in all hospital groups: about 17% of P. aeruginosa to imipenem, 50% of Haemophilus influenzae to ampicillin, 70% of Staphylococcus aureus to methicillin, and 70% of pneumococci to penicillin. In conclusion, nosocomial pathogens and problem resistant organisms are prevalent in smaller hospitals too, indicating nosocomial spread is a significant cause of the increasing prevalence of resistant bacteria in Korea.

Tibial bone defects treated by internal bone transport using the Ilizarov method

We reviewed 27 cases of tibial bone defects treated by internal bone transport using the Ilizarov method. The causes of the bone defects were open fractures in 14 segments and infected non-unions in 13. The average length of the defects was 8.3 cm (range, 3-20 cm). There were 21 one-level tibial transports, 3 two-level tibial transports, 1 one-level tibial transport with fibular transport, and 2 fibular transports. At the docking site, 25 segments underwent bone grafting. Eleven of the 25 were Papineau-type open cancellous bone grafts. Acute shortening or docking was performed in 10 segments. Bone union was obtained in every instance. The average time of external fixation was 8 months and the average time to union was 7.1 months. Bone grafting at the docking site is recommended in order to shorten the duration of treatment and to prevent refracture and non-union.

Learning needs of congestive heart failure patients

Congestive heart failure (CHF) affects approximately one-half million Canadians and five million Americans. Patient education is a vital component of nursing care of this population, with the goals of improving the CHF patient's quality of life, minimizing symptoms and hospital admissions, and reducing length of hospital stay. A review of the literature related to the educational needs of CHF patients reveals minimal research. The purpose of this study was to compare the perceived learning needs of CHF patients by patients and nurses, and to identify existing gaps between their perceptions. Fifty (50) CHF patients and 47 cardiac nurses were surveyed using a modified version of the CHF Patient Learning Needs Inventory developed by Hagenhoff et al. This instrument measured the importance of specific learning topics within the categories of anatomy and physiology, medications, diet, risk factors, activity, psychological factors, and other pertinent information. The results indicated that both groups found most information "moderately" to "very" important to learn. The patients generally rated all information items higher than nurses did. The most significant finding was that the nurses rated the diet category as second in importance, while the patients rated it last. The results from the study will be incorporated into a needs-based educational program for CHF patients.

(Ta/Si) multilayer as a wide-bandpass monochromator material

Specular and non-specular X-ray reflectivity intensities of a (Ta/Si)(60) multilayer sample were measured to characterize its interface structure. Since the multilayer has a good reflectance at its multilayer peaks, its performance as a wide-bandpass monochromator for X-ray scattering experiments of polymers has been tested.

Controlled release of platelet-derived growth factor from porous poly(L-lactide) membranes for guided tissue regeneration

Platelet-derived growth factor-BB (PDGF-BB) was incorporated into porous poly (L-lactide) (PLLA) membranes with an aim of improving early bone healing in guided tissue regeneration (GTR) therapy. Porous PDGF-BB loaded membranes were fabricated by coating PDGF-BB-dissolved PLLA methylene chloride-ethyl acetate solutions on polyglycolic acid (PGA) meshes. Release kinetics of PDGF-BB, biologic activity, degradability and guided tissue regenerative potentials of the membranes were investigated. Release of PDGF-BB could be controlled by adding bovine serum albumin that may provide porous diffusion channels for PDGF-BB release and by varying initial loading content of PDGF-BB. Biologic activity of PDGF-BB in the membranes was ascertained by fibroblast chemotaxis. PDGF-BB loaded membranes maintained proper degradation property for periodontal application. PDGF-BB loaded membrane markedly increased new bone formation in rat calvarial defects, and completed bony reunion after 2 weeks of implantation period. These results suggested that PDGF-BB loaded PLLA membrane might potentially enhance guided tissue regenerative efficacy.

A case of type IIa early gastric cancer developed in pernicious anemia

Pernicious anemia is an autoimmune disease characterized by a gastric mucosal defect which results in an insufficiency of intrinsic factor to facilitate the absorption of the physiologic amount of cobalamin. Increased risk of cancers of the stomach has been reported for patients with pernicious anemia. We report here a case of a 65 year old woman who had been diagnosed as having pernicious anemia 16 months previously, was receiving monthly vitamin B12 injections, and developed early gastric cancer type IIa by routine follow-up gastroscopic examination. This patient underwent endoscopic mucosal resection for an early gastric cancer lesion with a free resection margin.

[The fate of the old Jejoong Won following the establishment of the new Jejoong Won (Severance Hospital)]

Dr. Allen, the first Protestant missionary in Korea, had an opportunity of saving the life of the queen's nephew shortly after his arrival in Korea in 1884. In gratitude the King established the Royal Korean Hospital (Jejoong Won), the first hospital in Korea, and appointed Dr. Allen in charge of the medical affairs of the hospital. After Dr. Allen's resignation from the mission, the work was successively carried on by Drs. JW Heron, RA Hardie, CC Vinton and OR Avison, the last of whom arrived in 1893. In 1894 the connection of the Hospital with the Korean Government was severed and the work taken over by the Northern Presbyterian Mission. Since then, it has been a distinctly mission institute. In 1900, while attending the Ecumenical Conference of Foreign Missions in Carnegie Hall, New York, Dr. Avison made the acquaintance of a philanthropist LH Severance, who made a gift of $10,000 for a new hospital. This building, the first modern hospital in Korea, was opened and dedicated in 1904. It was named the Severance Hospital. As the new hospital was built, the old hospital building was to be returned to the Korean Government according to the agreement made in 1894. On retaking the old hospital, the Korean Government paid $30,289.99 won for the renovation of the original building and new buildings established in the site during the period of Avison's entire charge of Jejoong Won. The old hospital building was used as an official residence for a diplomatic adviser Stevens, who was assassinated for his pro-Japan activities, and as a social club for Japanese officials.

[A study on medical educational system in North Korea]

Medical education in North Korea began with 2 medical colleges established during the 1930s and 1940s, and each Province came to have one medical college by the 1970s. It is presumed to exist 14 medical colleges in 1992. Apart from medical colleges, there are several kinds of medical schools. the number of medical practitioners has increased as the number of educational institutes for medicine increased. In 1996, there was 29.7 medical practitioners for 10,000 persons. They have several kinds of academic degrees in North Korea. They include: Wonsa, candidate Wonsa, doctor, vice-doctor, candidate doctor. In the university they have professor, associate professor, associate professor, lecturer, and research assistant. Academic degrees and positions are given not by the university nor research institute, but by the Government Board for Awarding Academic Degree and Position. Concerning research institutes, there is Chosen Institute for Medical Science that once was a medical research center under the Central Science Academy, and became an independent institute in 1963. Besides this institute, universities have their own research institutes, and there are also some other independent institutes.

[A study on the movement for establishing a private isolation hospital under the rule of Japanese imperialism]

Koreans had an ill feeling against the only public isolation hospital, and their ill feeling was a cause the movement for establishing a private isolation hospital. The bad seating capacity and the nearness to downtown of public isolation hospital, and some violence caused in the course of taking a patient to the public isolation hospital were concrete causes of the movement for establishing a private isolation hospital. The three purposes of the movement for establishing a private isolation hospital are as follows. First, for the purpose of removing the national ill feeling, Koreans had to establish the isolation hospital by themselves. Second, for the purpose of curing the patients, doctors needed to use Oriental medicine together. Third, for the purpose of doing away with the anxiety of infection, the isolation hospital had to be located in a distant place from downtown. The movement for establishing a private isolation hospital didn't succeed. It only ended up establishing a contagious ward in Severance hospital. Because whenever an isolation hospital was planned to be constructed somehere, the residents worrying about the infection opposed to the construction, and enough money didn't be gathered. Abve all, rich pro-Japanese men didn't contribute enough money. The middle and lower classes contributed almost all of the money. The movement for estabishing a private isolation hospital was the extension of anti-Japanese national feeling that sprung from the March 1st movement. In view of strenghtening Korean ability, the movement for establishing a private isolation hospital had a common cause with the Shilryokyangsong movement in the early 1920s.

Antibiotic-impregnated cement beads in the treatment of chronic osteomyelitis

Fifty-four patients with chronic osteomyelitis of the long bones were treated at Gyeong-Sang National University Hospital between 1985 and 1993 using the cement bead technique. We studied the results of thirty-one patients who were followed up for 3 years or more. The average duration of follow-up was 4 years and 2 months (range: 3 to 7 years). All of the patients were treated by a two-stage operation; primary saucerization with implantation of antibiotic-impregnated polymethylmethacrylate beads and secondary bone grafts. The most recent follow-up examinations and analyses revealed that 17 patients (55%) were completely free of infection. Ten patients (32%) required repeated procedures of curettage and/or bone grafting. Amputations were performed on 4 patients.

Clinical and microbiological effects of minocycline-loaded microcapsules in adult periodontitis

Clinical and microbiological effects of subgingival delivery of 10% minocycline-loaded (MC), bioabsorbable microcapsules were examined in 15 adult periodontitis patients. Patients received oral hygiene instruction 2 weeks prior to the study. At baseline (day 0) all teeth received supragingival scaling (SC); 2 quadrants received no further treatment and 1 quadrant received subgingival scaling and root planning (SRP). In the fourth quadrant, the tooth with the deepest probing sites (at least 1 site > or = 5 mm) was treated with minocycline microcapsules. The sites were evaluated at baseline and weeks 1, 2, 4, and 6. Clinical indices included bleeding on probing (BOP), probing depths (PD), and attachment loss (AL). Microbiological evaluations included percent morphotypes by phase-contrast microscopy; cultivable anaerobic, aerobic, and black-pigmented Bacteroides (BPB); and percent Porphyromonas gingivalis, Prevotella intermedia, Eikenella corrodens, and Actinomyces viscosus by indirect immunofluorescence. In the SC + MC group, BOP, PD, and AL were significantly reduced from baseline for weeks 1 to 6. BOP in the SC + MC group was significantly reduced compared to the SRP group from weeks 2 to 6. In the SC + MC group the percent of spirochetes and motile rods decreased and the percent of cocci increased after 1 week. The increased cocci and decreased motile rods were statistically greater at weeks 4 and 6 in the SC + MC group compared to the SRP group. This study demonstrates that local subgingival delivery of 10% minocycline-loaded microcapsules as an adjunct to scaling results in reduction in the percent sites bleeding on probing greater than scaling and root planning alone and induces a microbial response more favorable for periodontal health than scaling and root planing.

Supracondylar osteotomy with Ilizarov fixation for elbow deformities in adults

Stable fixation after a corrective supracondylar osteotomy in adults is difficult because of the irregularity of the area of bony contact, displacement of the fragments, the predominance of cortical bone, and the need for early mobilisation. We have used the Ilizarov apparatus for fixation in 15 patients who were treated by complex osteotomies with displacement of fragments for cubitus varus or valgus. Most patients with cubitus varus required medial displacement with rotation of the distal fragment. Those with cubitus valgus required lateral shift of the distal fragment to reduce the medial prominence of the elbow that would otherwise result. All osteotomies united within the expected time without loss of correction, despite early mobilisation. Complications related to the fixation were few and had resolved at the long-term follow-up.

Experimental determination of a geometric form factor in a lidar equation for an inhomogeneous atmosphere

We experimentally determine a geometric form factor for an inhomogeneous atmosphere by using the polynomial regression method in a lidar equation.

Deconvolution of long-pulse lidar signals with matrix formulation

A deconvolution technique for deriving more resolved signals from lidar signals with typical CO(2) laser pulses is proposed, utilizing special matrices constructed from the temporal profile of laser pulses. It is shown that near-range signals can be corrected and small-scale variations of backscattered signals can be retrieved with this technique. Deconvolution errors as a result of noise in lidar data and in the laser pulse profile are also investigated numerically by computer simulation.

Biological effects of drug-loaded biodegradable membranes for guided bone regeneration

The biological effects of drug-loaded biodegradable novel membrane for guided bone regeneration (GBR) was evaluated. The membranes were polyglycolic acid mesh coated with poly-L-lactic acid containing flurbiprofen, tetracycline or PDGF-BB. Porous structure was generated in the membranes by using a phase inversion method. The membrane was less toxic, nicely biodegradable and biocompatible for 8 wk after implantation in the dorsal skin of the rat. The drugs released from the membranes were shown to be effective for new bone formation. Tetracycline, flurbiprofen or PDGF-BB loaded membrane was markedly effective for osteoid tissue and new bone formation in the bony defect prepared in rat calvaria to compare with that by unloaded membrane. These results suggested that drug-loaded biodegradable barrier membrane might be a potential tool for GBR in periodontal therapy.

Stress analysis of a cantilevered fixed partial denture with normal and reduced bone support

A two-dimensional finite element model was constructed to analyze the simulated mechanical behavior of a cantilevered fixed partial denture. The variations of the models were made by altering the degree of bone support, the number of splinted abutments, and the length of the pontics. High stress concentrations were observed around the connectors of the fixed prosthesis and the tooth closest to the cantilever. Reduced bone support increased the deflection and stress concentrations. There was reduction in displacement and stress concentration when the teeth were splinted together. To improve the prognosis of the fixed partial denture cantilever, the number of abutments should be increased and the number of pontics decreased.

ICG-enhanced digital angiography and photocoagulation of choroidal neovascularization in age-related macular degeneration

Choroidal neovascular membranes are often poorly defined on fluorescein angiography because of fluorescein leakage or blockage of hyperfluorescence by overlying hemorrhage, lipid, turbid fluid, or pigment. Indocyanine green (ICG) is a highly protein-bound dye in the near infrared portion of the spectrum. Therefore, ICG remained in and around the neovascular membrane and enhanced the visualization of certain membranes poorly defined with fluorescein. ICG penetrated through the overlying turbid tissue, and improved the visualization of the underlying choroidal neovascular membrane. Using an infrared angiography system, the authors obtained 21 ICG-angiograms with suspected choroidal neovascularization, and compared them to fluorescein angiograms. In 5 of the 21 eyes, occult choroidal neovascularization was well delineated on the ICG angiograms. In 2 eyes, we were able to detect a well-defined choroidal neovascular membrane underlying a subretinal hemorrhage. In 12 of the 21 eyes with choroidal neovascular membrane, we performed argon-green laser photocoagulation applying the overlay technique of the ICG angiogram to red-free photo or the early fluorescein angiogram, and evaluated the effect of full coverage laser treatment.