OBJECTIVE: This study was performed to investigate an appropriate degree of prestretch for orthodontic synthetic elastomeric chains focusing on time-dependent viscoelastic properties. METHODS: Orthodontic synthetic elastomeric chains of two brands were prestretched to 50, 100, 150, and 200% of the original length in one and three cycles, and the hysteresis areas of the obtained stress-strain curves were determined. Acrylic plates were employed to maintain constant strain during the experiment. A total of 180 samples were classified into nine groups according to brand, and their stresses and permanent deformations were measured immediately after prestretch (0 hour), after 1 hour and 24 hours, and after 1, 2, 3, 4, 5, 6, 7, and 8 weeks. The relationship between stress relaxation and permanent deformation was investigated for various degrees of prestretch, and the estimated stress resulting from tooth movement was calculated. RESULTS: The degree of prestretch and the stress relaxation ratio exhibited a strong negative correlation, whereas no correlation was found between the degree of prestretch and the average normalized permanent strain. The maximal estimated stress was observed when prestretch was performed in three cycles to 200% of the original length. CONCLUSIONS: Although prestretch benefited residual stress, it did not exhibit negative effects such as permanent deformation. The maximal estimated stress was observed at the maximal prestretch, but the difference between prestretch and control groups decreased with time. In general, higher residual stresses were observed for product B than for product A, but this difference was not clinically significant.
Elastomers* ; Relaxation* ; Tooth Movement

Sideroblastic anemia is a rare, heterogeneous group of disorders characterized by hyperferremia, microcytic hypochromic anemia, and bone marrow erythroid hyperplasia with the presence of numerous ringed sideroblasts. We describe herewith the case of a rare coincidence of sideroblastic anemia and mitral valve prolapse with resultant regurgitation in a 2-year-old boy. In addition to the inherent propensity for the development of cardiac dysfunction in sideroblastic anemia due to transfusion-associated myocardial iron overload and chronic anemia, a coincidence of MVP will further increase the likelihood of the morbidity or mortality of th patient. in this patient. After response to pyridoxine, the patient remains in good condition with stable hemoglobin levels.
Anemia ; Anemia, Hypochromic ; Anemia, Sideroblastic* ; Bone Marrow ; Child, Preschool ; Humans ; Hyperplasia ; Iron Overload ; Male* ; Mitral Valve Prolapse* ; Mitral Valve* ; Mortality ; Pyridoxine*

Common complications of Henoch-Schonlein purpura (HSP) that lead to surgical intervention include intussusception, perforation, necrosis, and massive gastrointestinal bleeding. Acute appendicitis is rarely seen as a complication of HSP. A sevenyear-old boy was admitted for arthralgia, abdominal pain, hematochezia, melena, and purpuric rash on the lower extremities. On admission day abdominal ultrasonography was normal, but on day 5, he became pyrexial and developed right iliac fossa pain and tenderness with guarding. Ultrasonography showed distended appendix surrounded by hyperechoic inflamed fat. On exploration an acutely inflamed, necrotic appendix was removed and grossly there was an appendiceal perforation in the appendiceal tip. Microscopically some of the small blood vessels in the submucosa showed fibrinoid necrosis with neutrophilic infiltrations. The authors report the case of a child who developed acute perforative appendicitis requiring appendectomy while on treatment for HSP.
Appendicitis/*diagnosis/*etiology ; Child ; Diagnosis, Differential ; Humans ; Male ; Purpura, Schoenlein-Henoch/*complications/*diagnosis

X-linked severe combined immunodeficiency (X-SCID) is a rare, life-threatening immune disorder, caused by mutations in the gamma c chain gene, which encodes an essential component of the cytokine receptors for interleukin-2 (IL-2), IL-4, IL-7, IL-9, IL-15, and IL-21. A 13-month-old boy with recurrent infections who had reduced serum immunoglobulin levels and decreased numbers of CD3, CD16/56 cells was evaluated for gamma c chain gene mutation and protein expression. The patient had a C-to-T point mutation at nucleotide position 690, one of the hot spots, resulting in a single amino acid substitution of cysteine for arginine (R226C), as determined by direct sequencing and PCR-RFLP. The patient's mother was a heterozygous carrier. Percutaneous umbilical cord blood sampling was performed at the 6-month of gestation in a subsequent pregnancy. As the immunophenotype of the fetus showed an identical pattern, the pregnancy was terminated and genetic analysis of the abortus confirmed recurrence. This is the first report of the molecular diagnosis of X-SCID in Korea. Genetic analysis of the gamma c chain gene is useful for definite diagnosis and genetic counseling for X-SCID.
Arginine/chemistry ; Cysteine/chemistry ; DNA/metabolism ; DNA Mutational Analysis ; Female ; Flow Cytometry ; Genetic Counseling/*methods ; Heterozygote ; Human ; Immunoglobulins/metabolism ; Immunophenotyping/methods ; Korea ; *Linkage (Genetics) ; Male ; *Mutation ; Pedigree ; Point Mutation ; Polymerase Chain Reaction ; Polymorphism, Restriction Fragment Length ; Receptors, Immunologic/*genetics ; Sequence Analysis, DNA ; Severe Combined Immunodeficiency/*diagnosis/*genetics ; Support, Non-U.S. Gov't ; Time Factors ; *X Chromosome

PURPOSE: Twins have a higher mortality and morbidity than singletons. Co-twin with one fetal death is particularly at risk. We investigated the neonatal outcome of live co-twins when one fetus had died after the 20th gestational week, and associated risk factors. METHODS: A retrospective study was performed in fifteen cases of twin pregnancy with single intrauterine fetal deaths after the 20th gestational week during the period from January 1996 to December 2000 at Chonnam University Hospital. RESULTS: Gestational age was 33.7+/-3.2 weeks, birth weight was 1,992+/-592 g. Interval between one fetal death being detected and the delivery of a live co-twin was 32.4+/-29.5 days. There were 11 cases(73.3%) of premature babies less than 37 gestational weeks. Main causes of preterm delivery were preterm labor and premature rupture of membranes. Hematologic findings suggesting disseminated intravascular coagulopathy(DIC) were not found in all mothers before delivery, and was not associated with DIC and encephalomalacia of the live co-twin. Perinatal outcome of fifteen live co-twins was as follows : six were normal(40%), three were DIC(20.0%), three were encephalomalacia(20.0%), one suffered intrauterine growth retardation, there was one case of twin to twin transfusion syndrome, and one of congenital heart disease(atrial septal defect with pulmonary stenosis). The occurrence of DIC and encephalomalacia in live co-twins was not related to placental chorionicity, birth weight, gestational week, and the interval between the detection one fetal death and the delivery of a live co-twin. CONCLUSIONS: We could not find any maternal hematologic problems in twin pregnancies complicated by one fetal death. Twenty percent of live co-twins showed DIC and encephalomalacia. However, its associated risk factors were not found. We need to investigate more closely the cases of live co-twins with one intrauterine fetal death.
Birth Weight ; Chorion ; Dacarbazine ; Encephalomalacia ; Female ; Fetal Death* ; Fetal Growth Retardation ; Fetofetal Transfusion ; Fetus ; Gestational Age ; Heart ; Humans ; Jeollanam-do ; Membranes ; Mortality ; Mothers* ; Obstetric Labor, Premature ; Pregnancy ; Pregnancy, Twin* ; Retrospective Studies ; Risk Factors ; Rupture

The treatment for full thickness skin defect with the full or split-thickness autograft was often associated with aesthetically poor result, hypertrophic scar or extensive injury on donor site. Because of this donor morbidity, the use of artificial dermis was considered, which was the substrate of collagen or collagen cross-linked with polyglactin or polylactin. Unfortunately this substrate was void of advantages for the artificial dermis but was of easy biodegradability, antigenicity, or cytotoxic property. Currently chitosan is given attention by many investigators for its biochemical properties in wound healing process. Chitosan is the deacetylated derivative of chitin, which is a polymer of 2-amino-2-deoxy glucose with chemically active free amino group. Chitosan facilitates wound healing process, and then stimulates migration of polymorphonuclear cell(PMN) and macrophage, release of IL-8 and accelerates collagen synthesis surely with vascularization. Indeed chitosan supplies the resistance against bacterial infection of the wound. In this study, we have investigated the clinical applicability of the artificial dermal substrate which is cross-linked of collagen and GAG with chitosan, which we have applied on the full thickness skin defect in Fisher rat. The conclusions are as the follows: 1. There was sufficient vascularization in the grafted dermal substrate for STSG after 2 weeks of artificial dermis grafting. 2. Four 4 weeks after artificial dermis grafting, the architecture of the dermal substrate was maintained in about half amounts and the half of dermal skeleton was replaced with the newly formed dermis(neodermis). In conclusion, the dermal substrate used in this study is available enough for wound of full thickness skin defect.
Animals ; Autografts ; Bacterial Infections ; Chitin ; Chitosan ; Cicatrix, Hypertrophic ; Collagen ; Dermis ; Equipment and Supplies ; Glucose ; Humans ; Interleukin-8 ; Macrophages ; Polyglactin 910 ; Polymers ; Rats ; Research Personnel ; Skeleton ; Skin ; Tissue Donors ; Transplants ; Wound Healing ; Wounds and Injuries

PURPOSE: This study was undertaken to investigate the seroepidemiologic pattern of Helicobacter pylori (H. pylori) and hepatitis A virus (HAV) infections in children. METHODS: A total of 315 serum samples were obtained from healthy children, living in Gwangju and Chonnam area. All serum samples were assayed for H. pylori IgG level using enzyme immunoassay techniques. HAV IgG level in serum were tested by a competitive radio-immunoassay in 215 subjects. The age-specific seroprevalence of H. pylori and HAV was separately analysed. The concordance of seropositivity and seronegativity between H. pylori and HAV infection was examined by the kappa statistic analysis. RESULTS: Seropositivity was found in 17.5% (55/315) and 30.2% (65/215) of the subjects for H. pylori and HAV, respectively. Cross-tabulation of these data showed that 21 subjects (9.8%) were seropositive and 135 (62.8%) were seronegative for both H. pylori and HAV, 15 (7.0%) were seropositive for only H. pylori and 44 (20.5%) for only HAV. The seroprevalence of H. pylori and HAV increased significantly with age. There was a slight agreement between H. pylori and HAV seropositivity (kappa=0.26). CONCLUSION: This study shows a slight similarity in the concordance of seropositivity and seronegativity between H. pylori and HAV infection and provides evidence that H. pylori and HAV may share a common mode of transmission.
Child* ; Epidemiology ; Gwangju* ; Helicobacter pylori* ; Helicobacter* ; Hepatitis A virus* ; Hepatitis A* ; Hepatitis* ; Humans ; Immunoenzyme Techniques ; Immunoglobulin G ; Jeollanam-do* ; Seroepidemiologic Studies

PURPOSE: This study was undertaken to determine the incidence of chromosome 22q11 deletion in patients with infundibular ventricular septal defect(VSD). METHODS: Sixty-two children with infundibular VSD were included in this study from January 1999 to December 2000. Chromosome 22q11 deletion was confirmed by FISH, using LSI DiGeorge/VCFS region dual color probe(Vysis, USA). RESULTS: Thirty-two patients had conotruncal cardiac defects:tetralogy of Fallot (TOF) in 15; TOF with absent pulmonary valve in 1; VSD with pulmonary atresia in 7; truncus arteriosus in 3; double outlet right ventricle in 2; interrupted aortic arch in 2; transposition of the great arteries in 2. Thirty patients had isolated infundibular VSD without conotruncal cardiac defect:perimembranous infundibular VSD in 15; subarterial infundibular VSD in 9; muscular infundibular VSD in 6. Chromosome 22q11 deletion was observed in 8 patients(male 5, female 3):TOF 2; VSD with pulmonary atresia 4; truncus arteriosus 1; perimembranous infundibular VSD 1. All of the patients with chromosome 21q11 deletion showed typical facial appearance. Low incidence was found of chromosome 22q11 deletion in patients with infundibular VSD without conotruncal cardiac defect than in those with conotruncal cardiac defect(3.3% vs 21.9%). CONCLUSION: These data indicate that a small proportion of isolated infundibular VSD is pathogenetically related to deletion of chromosome region 22q11.
Aorta, Thoracic ; Arteries ; Child ; Double Outlet Right Ventricle ; Female ; Heart Septal Defects, Ventricular* ; Humans ; Incidence ; Pulmonary Atresia ; Pulmonary Valve ; Truncus Arteriosus

Pituitary abscess is a rare condition of the pituitary gland. We report MR imaging findings in two cases of surgically-confirmed pituitary abscess occurring in women aged 39 and 28. In both a peripheral rim enhancing lesion, similar to abscesses in other areas of brain, was seen in the pituitary fossa.
Abscess* ; Brain ; Female ; Humans ; Magnetic Resonance Imaging* ; Pituitary Gland

PURPOSE: To evaluate MR imaging findings of degenerating parenchymal neurocysticercosis and to determine the characteristics which distinguish it from other brain diseases. METHODS: MR imagings of 19 patients (56 lesions)of degenerating parenchymal neurocysticercosis were retrospectively evaluated, focusing on the size and locationof lesions, signal intensity patterns of cyst fluid and wall, the extent of the surrounding edema and features of contrast enhancement. RESULTS: Degenerating parenchymal neurocysticercosis was located in gray or subcortical white matter in 89.3% of 56 lesions(50/56); most of these (98.2%) were smaller than 2cm in diameter. Cyst fluidsignal was hyperintense relative to CSF on T1 and proton density weighted images (92.9%). A hypointense signal rimof the cyst wall was noted in the lesions on proton density (92.9%) and T2 weighted (98.2%) images. Surrounding edema was mostly mild. Peripheral rim enhancement was noted in all lesions, and this was frequently irregular and lobulated (67.9%) with a focal defect in the enhancing rim (41.1%). CONCLUSION: Findings which could be helpfulin distinguishing degenerating parencymal neurocysticerosis from other brain diseases are as follows : small, superficial lesions ; hyperintense signal of the cyst fluid on T1 and proton density weighted images ; hypointense signal of the cyst wall on proton density and T2 weighted images ; relatively mild extent of surrounding edema,and peripheral rim enhancement which is frequently irregular and lobulated with a focal defect in the enhancingrim.
Brain Diseases ; Cyst Fluid ; Cysticercosis ; Edema ; Humans ; Magnetic Resonance Imaging ; Neurocysticercosis* ; Parasites ; Protons ; Retrospective Studies