Heat treatment which removes internal stress enhances the mechanical properties of the orthodontic arch wire. The main purpose of this experiment was to investigate the effects of the heat treatment on the mechanical properties of the Elgiloy wire. The Elgiloy wire, 0.016" X 0.022" and 0.018" X 0.025", were heat treated in an electric oven for 5, 10 and 15 minutes at selected temperatures between 300 and 900degreesC. Tensile strength and load deflection rate were measured to reveal the changes of mechanical property at various con?ditions, and each specimen was observed under metallurgic microscope. Also to trace the precipitation material due to overheat treatment, a qualitative analysis was carried out with EDS system. It was found that heat treatment at a low temperature caused an increase in the tensile strength and bending resistance, and a maintenance in the fibrous in the tensile strength and bending resistance, and a maintenance in the fibrous structure of both sizes of wire. The changes observed in properties and appearance were probably due to the relief of internal stresses incurred in the metal during cold working. In both sizes of wire the tensile strength and the bending resistance continued to decrease at high temperature, and the fibrous structure continued to disappear then was not observed at 900degreesC. The carbide precipitation founded in grain boundary at 750degreesC probably was other elements carbide (Ni, Co) except Cr. The grain growth was observed at 1100degreesC. Optimum heat treatment for the 0.016" X 0.022" Elgiloy wire was 10 minutes at 500degreesC, and for the 0.018" X 0.025" Elgiloy wire it was 5 to 15 minutes at 500degreesC.
Edible Grain ; Hot Temperature* ; Tensile Strength

Fracuture-dislocation of the cuboid is an extremely rere injury compared with fracture-dislocation of other tarsal bones. We report a case of the fracture-dislocation of the cuboid treated by open reduction and internal fixation.
Tarsal Bones

PURPOSE:This study was performed to investigate clinical characteristics and the etiology of cervical lymphadenopathy in children. METHODS:A clinical review of 240 cases of children under the age of 18 who were admitted with cervical lymphadenopathy from January 2002 to December 2007. RESULTS:Cervical lymphadenopathy was diagnosed as follows:clinically diagnosed lymphadenitis (52.1%), abscess (15%), necrotizing lymphadenitis (7.9%), reactive hyperplasia (5.4 %), tuberculous lymphadenitis (4.2%), Kawasaki disease (2.9%) and malignancy (2.5%). Abscess was presented as an acute lesion (94.1%) with less than 2 weeks of fever (69.4 %) and tuberculous lymphadenitis was presented as a chronic lesion (62.5%) without fever (90 %). Malignant disease (100%) and necrotizing lymphadenitis (62.5%) were found in chronic lesion of older children with systemic symptoms (40% and 37.5%, respectively). Leukopenia (57.9%) with various duration of fever occured in case of necrotizing lymphadenitis. CONCLUSION:Clinically diagnosed lymphadenitis (52.1%), abscess (15%), necrotizing lymphadenitis (7.9%), reactive hyperplasia (5.4%), tuberculous lymphadenitis (4.2%), Kawasaki disease (2.9%) and malignancy (2.5%) were found in cervical lymphadenopathy. Although cervical lymphadenopathy was commonly caused by a benign infectious process, a more serious disease was not rare, which may have different clinical characteristics including age, duration of fever and disease, previous or accompanying symptoms, or white cell counts. Meticulous combination of clinical characteristics, history, physical examination and workup as well as follow-up may be the most important for the proper approach on cervical lymphadenopathy in children.
Abscess ; Cell Count ; Child ; Fever ; Humans ; Hyperplasia ; Leukopenia ; Lymphadenitis ; Lymphatic Diseases ; Mucocutaneous Lymph Node Syndrome ; Physical Examination ; Tuberculosis, Lymph Node

BACKGROUND/AIMS: This study evaluated medical students' experience performing basic clinical skills with real patients in a tertiary hospital and their response to clinical skill training in the Skills Center during their clerkship in internal medicine. METHODS: We surveyed 169 third-year students at the end of the internal medicine clerkship. The questionnaire included questions on their experience sampling blood and inserting intravenous (IV) catheters with real patients, success with their first patient, and the usefulness of the Skills Center during the clinical clerkship. RESULTS: Of the 169 students, 145 (86%) answered the questionnaire. Two (5%) of 39 students had not sampled blood and 22 (56%) had not inserted an IV catheter during the 8 weeks of the internal medicine clerkship. Two (6%) of 35 students had not sampled blood and 8 (23%) had not inserted an IV catheter during 32 weeks of the 3rd-year clinical clerkships. The partial or complete success rate for performing the skills with real patients was 93% for blood sampling and 79% for IV catheter insertion. Ninety (62%) students stated that skill training in the Skills Center during the clinical clerkship improved their basic clinical skills and 62 (43%) agreed that it increased their confidence to perform those skills on real patients. CONCLUSIONS: A significant number of medical students do not experience basic clinical skills with real patients during the clinical clerkship in a university hospital, although they had relatively high success rates performing those skills.
Catheters ; Clinical Clerkship ; Clinical Competence ; Humans ; Internal Medicine ; Students, Medical ; Tertiary Care Centers ; Surveys and Questionnaires

BACKGROUND: Although the incidence of hepatitis A infection has dramatically declined in developed countries, it is still endemic in many of developing countries, and sporadic outbreak has developed in many middle classed endemic area. Many reports indicate that hepatitis A vaccine would have to be used for widespread immunization of infants, who live in endemic or non-endemic region, for eliminating this infection from circulation. Therefor, the optimal immunization schedule and dose of vaccine should be determined. Recent several studies suggested that high dose hepatitis A vaccination at the time of disappearance of maternal antibody promise protectable immunogenicity in infants. The purpose of our study to find out the prevalence and persistence of maternal HAV antibodies in Korean infants (below 2 years old age). METHODS: 60 mother without past-history of hepatitis A, and 300 heathy infants without history of hepatitis A vaccination and intra-familial contact history of hepatitis A were enrolled in this study. The infants below 2 years old age were classified into 5 groups as following; 0~3 months, 4~6 months, 7~9 months, 10~12 months, 13~24 months, and the number of each group were 60 and sex distribution of each group was equal. Positive rates of Anti-HAV were determined by ELISA. And comparisons of seroprevalence of anti- HAV between groups were analyzed by ANOVA repeated t-test. RESULTS: The seropositive rate of maternal group was 81.7%, and the seropositive rate of 0~3 months of age group was 43.3%. The seroprevalence of anti- HAV significantly declined after 4~6 months of age, and reached below 10% at the age of 7~9 months of age and the low rate of anti-HAV maintained until 2 years old age. And positive rates of anti-HAV showed no significant differences between males and females. CONCLUSION: The results of our study showed that the seroprevalence of anti-HAV significantly declined after 4~6 months of age and the anti-HAV almostly disappeared at 7~9 months of age. So, low seropositive rate of anti-HAV at 7 months of age may justify trials on infant vaccination in Korea.
Antibodies ; Child, Preschool ; Developed Countries ; Developing Countries ; Enzyme-Linked Immunosorbent Assay ; Female ; Hepatitis A ; Hepatitis A Antibodies ; Hepatitis A Vaccines ; Hepatitis* ; Humans ; Immunization ; Immunization Schedule ; Incidence ; Infant* ; Korea ; Male ; Mothers ; Prevalence* ; Seroepidemiologic Studies ; Sex Distribution ; Vaccination

PURPOSE: Necrotizing pneumonitis is a complication of severe invasive lobar pneumonia characterized by necrotic foci in consolidated areas and its development may be due to excessive host cell-mediated immune response. Necrotizing pneumonitis caused by Mycoplasma pneumoniae (M. pneumoniae) in children and its successful treatment have been reported. We reviewed 5 cases to determine the disease course and outcome in pediatric patients with necrotizing pneumonitis resulting from M. pneumoniae infection. METHODS: Five patients with necrotizing pneumonitis caused by M. pneumoniae who were diagnosed and treated in the Department of Pediatrics, Uijeongbu St. Mary`s Hospital from January 2003 to December 2006 were reviewed in this study. Sex, age, clinical manifestations, laboratory and radiologic findings, treatments, and long-term follow-up outcomes of these patients were analysed retrospectively. RESULTS: One patient was a boy and others were girls. All were less than 5 years of age and had no immunocompromised conditions. Lower pH and glucose, higher protein and LDH were observed in pleural fluid. On the radiologic examinations, all had multilobar pneumonic involvements, especially in the right lobes and lower lobes. Necrotizing pneumonitis was diagnosed on chest CTs taken between two and 20 days following admission. The necrotic foci were identified as multiple low-attenuation changes within the contrast-enhanced consolidation areas mainly in the lower lobes of the affected side of lung. Cavitary necrosis was shown in 3 patients and persisted as pneumatoceles, which disappeared on the follow-up chest radiographs nearly up to 7 months following admission. Macrolide and broad-spectrum antibiotics were administered in all patients and chest tube drainage was performed in 2 patients. Systemic steroid therapy was added in 4 patients. Of those four, 2 patients, both under 2 years of age, improved more rapidly than others in clinical status and radiographic findings. In spite of steroid therapy, one patient died of acute respiratory distress syndrome. Consequently 4 patients were improved and discharged. Two patients who were under 2 ears were normalized and 2 patients who were 4 years of age showed remaining cavitation or fibrosis in the last follow-up chest radiographs. CONCLUSION: Our results may suggest though they are not yet proven nor have they been discussed extensively that younger patients show better prognoses than older children. Further well-designed and large scale studies may be warranted.
Anti-Bacterial Agents ; Chest Tubes ; Child* ; Drainage ; Ear ; Female ; Fibrosis ; Follow-Up Studies ; Glucose ; Humans ; Hydrogen-Ion Concentration ; Lung ; Male ; Mycoplasma pneumoniae* ; Mycoplasma* ; Necrosis ; Pediatrics ; Pneumonia* ; Pneumonia, Mycoplasma* ; Prognosis ; Radiography, Thoracic ; Respiratory Distress Syndrome, Adult ; Retrospective Studies ; Tomography, X-Ray Computed