The aims of this experiment were to investigate the strain and temperature changes simultaneously within autopolymerizing acrylic resin specimens. A computerized data acquisition system with an electrical resistance strain gauge and a thermocouple was used over time periods up to 180 minutes. The overall strain kinetics, the effects of stress relaxation and additional heat supply during the polymerization were evaluated. Stone mold replicas with an inner butt-joint rectangular cavity (40.0x25.0mm, 5.0mm in depth) were duplicated from a brass master mold. A strain gauge (AE-11-S50N-120-EC, CAS Inc., Korea) and a thermocouple were installed within the cavity, which had been connected to a personal computer and a precision signal conditioning amplifier (DA 1600 Dynamic Strain Amplifier, CAS Inc., Korea) so that real-time recordings of both polymerization-induced strain and temperature changes were performed. After each of fresh resin mixture was poured into the mold replica, data recording was done up to 180 minutes with three-second interval. Each of two poly (methyl methacrylate) products (Duralay, Vertex) and a vinyl ethyl methacrylate product (Snap) was examined repeatedly ten times. Additionally, removal procedures were done after 15, 30 and 60 minutes from the start of mixing to evaluate the effect of stress relaxation after deflasking. Six specimens for each of nine conditions were examined. After removal from the mold, the specimen continued benchcuring up to 180 minutes. Using a waterbath (Hanau Junior Curing Unit, Model No.76-0, Teledyne Hanau, New York, U.S.A.) with its temperature control maintained at 50degrees C, heat-soaking procedures with two different durations (15 and 45 minutes) were done to evaluate the effect of additional heat supply on the strain and temperature changes within the specimen during the polymerization. Five specimens for each of six conditions were examined. Within the parameters of this study the following results were drawn : 1. The mean shrinkage strains reached -3095mu epsilon, -1796mu epsilon and -2959mu epsilon for Duralay, Snap and Vertex, respectively. The mean maximum temperature rise reached 56.7degrees C, 41.3degrees C and 56.1degrees C for Duralay, Snap, and Vertex, respectively. A vinyl ethyl methacrylate product (Snap) showed significantly less polymerization shrinkage strain (p<0.01) and significantly lower maximum temperature rise (p<0.01) than the other two poly (methyl methacrylate) products (Duralay, Vertex). 2. Mean maximum shrinkage rate for each resin was calculated to ?31.8mu epsilon/sec, -15.9mu epsilon/sec and ?31.8mu epsilon/sec for Duralay, Snap and Vertex, respectively. Snap showed significantly lower maximum shrinkage rate than Duralay and Vertex (p<0.01). 3. from the second experiment, some expansion was observed immediately after removal of specimen from the mold, and the amount of expansion increased as the removal time was delayed. For each removal time, Snap showed significantly less strain changes than the other two poly (methyl methacrylate) products (p<0.05). 4. During the external heat supply for the resins, higher maximum temperature rises were found. Meanwhile, the maximum shrinkage rates were not different from those of room temperature polymerizations. 5. From the third experiment, the external heat supply for the resins during polymerization could temporarily decrease or even reverse shrinkage strains of each material. But, shrinkage re-occurred in the linear nature after completion of heat supply. 6. Linear thermal expansion coefficients obtained from the end of heat supply continuing for an additional 5 minutes, showed that Snap exhibited significantly lower values than the other two poly (methyl methacrylate) products (p<0.01). Moreover, little difference was found between the mean linear thermal expansion coefficients obtained from two different heating durations (p>0.05).
Acrylic Resins* ; Electric Impedance ; Fungi ; Heating ; Hot Temperature ; Kinetics ; Microcomputers ; Polymerization* ; Polymers* ; Relaxation

The current clinical technique for occlusal vertical dimension recording is based on marking the skin reference points on the patient's face and measuring between these pints using caliper-like device. And it is difficult to achieve reliable measurements by this technique because of movable soft tissue. The purpose of this study is to reveal the stability of skin reference points by comparing the relative movement between extra-oral skin reference points and intra-oral reference points using X-ray fluoroscope. 10 test subjects were divided into 2 groups : Group I (natural dentition) and Group II (denture-wearer whose vertical dimension was lost) and Group III consists of identical test subjects to Group II with their upper denture removed and record base inserted. Attaching the 3mm diameter steel ball to nose tip, chin and to existing denture (or record base), fluoroscopic examination and recording were taken during 2 jaw opening and closing movements. After subsequent digitization using personal compute, 1219 still pictures with 0.1 second interval were made. Using the 2 dimensional graphic software, measurements between reference points were executed. Dividing the entire jaw movement into 3 ranges (total, 1st half opening, 2nd half opening), rate of movement and relative movement between extra-oral and intra-oral reference points were calculated and statistically analyzed. The results of this study are as follows. 1. Within the same experimental group, no statistical difference was found in the stability of skin reference between lower lip point and chin point during total range of jaw opening and closing movement (p>.05). 2. In the first half range of jaw opening, statistical difference was found between Group I (natural dentition) and Group II (denture wearer) (p<.05). Group I has greater skin reference stability than Group II. 3. In the first half range of jaw opening, statistical difference was found between Group I and Group III (record base wearer) (p<.05). Group I has greater skin reference stability than Group III. 4. In the first half range of jaw opening, no statistical difference was found in the stability of skin reference between Group II and Group III (p>.05). 5. In the second half range of jaw opening, no statistical difference was found in the stability of skin reference between any experimental groups (p>.05). 6. In patients with their occlusal vertical dimension lost, employing other measuring references rather than skin is recommended because of low stability.
Chin ; Dentures ; Humans ; Jaw* ; Lip ; Nose ; Skin* ; Steel ; Vertical Dimension

This study was conducted to explore the feasibility of using the lead level in the hair of children as a screening test for lead intoxication of children and as an indicator for environmental pollution. Lead concentration of hair was measured for 268 seven to nine-year-old elementary school children in Taegu city (147 children) and Gampo. town(121 children). The lead level in hair was measured by atomic absorption spectrophotometer equipped with a graphite furnace atomizer. The following information was obtained for all children : sex, age, father's occupation and smoking habits, kinds of hair cleaner, fingernail biting habits, and status of the child's hands and clothing. The mean lead level in hair was 8.7+/-2-9 microg/g in the urban area and 7.7+/-2.2 pg/g in the rural area. There were significant differences between two groups(p(0.01). The difference of lead levels in hair measured by cleanliness of the child's hands (clean : 7.4+/- 2.7 pg/g, dirty : 8.2+/- 2.6 pg/g) and child's clothing(clean : 8.0+/- 2.5 microg/g, dirty : 9.3+/- 2.6 microg/g) were statistically significant, but other factors were not significant. In multiple regression analysis, difference of residency and age were significant variables for lead level in the hair of children. These findings suggest that measurement of lead level in the hair is a useful method for the screening of the lead intoxication of children and monitoring environmental conditions.
Absorption ; Child* ; Clothing ; Daegu ; Environmental Pollution ; Graphite ; Hair* ; Hand ; Humans ; Internship and Residency ; Mass Screening ; Nails ; Nebulizers and Vaporizers ; Occupations ; Smoke ; Smoking

No abstract available.
Congenital Abnormalities* ; Ring Chromosomes*

No abstract available.
Colitis, Ulcerative* ; Ulcer*

Diabetes mellitus (DM) is an important cause of organic impotence in man. The exact pathogenesis remains debatable although it has been focused on cavernosal neuropathy and/or endothelial dysfunction. This study was designed to investigate the effect of DM on penile erection, especially in association with nitric oxide synthase (NOS) in corpus cavernosum of diabetic rats. NOS studies of rat penis were performed in diabetic (DM was induced for 3, 6, 9, 12 weeks, respectively, by intraperitoneal administration of streptozotocin, 60mg/kg), in control and neurotomy group (3 weeks after bilateral cavernous nerve transection). The experiments consisted of nicotinamide dinucleotide phosphate (NADPH) diaphorase activity with spectrophotometric assay for NOS catalytic activity, NADPH diaphorase staining for the identification of NOS containing nerve fibers, and Western blotting analysis with anti-brain NOS antibody for the expression of neuronal NOS. Finally, these results were compared with erectile response to cavernous nerve stimulation in diabetic and in control rats. In assay of NADPH diaphorase activity, NOS activity decreased significantly in penis of diabetic rat as compared to that of controls. Between the diabetic groups, NOS activity was not seen significantly different, and in neurotomy groups it was similar to that of diabetic groups. On histochemical staining of penile tissues, the number of NADPH-positive nerve fibers in control group (a mean of 127+/-6 fibers recorded in 4 random fields on each corporal side) contrasted significantly with that of the bilateral cavernous nerve ablation group (a mean of 12+/-2). In diabetic group, the number of NOS-containing nerve fibers was gradually reduced along with duration of diabetes (from 92+/- 3 at 3 weeks to 28+/-3 at 12 weeks). In addition, analysis of blot density of neuronal NOS by Western blotting showed similar findings: 16% at 3 weeks and 8% at 12 weeks in diabetic group, 5% in neurotomy group and 27% in controls, based on the density of the rat cerebellum. Furthermore, erection response to cavernous nerve stimulation was also decreased in diabetic rats along with DM duration. The results, indicated that reduction of cavernous NOS, particularly, its neuronal form at the level of NO production plays an important role on the pathogenesis of erectile impotence in diabetic rats although the role of endothelial N0S in DM remains to be elucidated. Furthermore, cavernosal NADPH diaphorase staining and/or NOS activity may allow to characterize certain pathological condition, which comprise neurogenic impotence.
Animals ; Blotting, Western ; Cerebellum ; Diabetes Mellitus ; Erectile Dysfunction ; Male ; NADPH Dehydrogenase ; Nerve Fibers ; Neurons* ; Niacinamide ; Nitric Oxide ; Nitric Oxide Synthase ; Nitric Oxide Synthase Type I* ; Penile Erection* ; Penis ; Rats* ; Streptozocin

No abstract available.
Animals ; Mice* ; Mycobacterium bovis*

PURPOSE: To evaluate the surgical effect of anterior interbody fusion using a horizontal cylinder cage in a degenerative lumbar spine. MATERIALS AND METHODS: We evaluated 16 patients (at 20 levels) who received anterior interbody fusion using a horizontal cylinder cage in a degenerative lumbar spine or in secondary segmental lumbar instability following decompression at the same level from May 1997 to May 1998. Preoperative, postoperative, and follow-up radiographs were taken to compare the posterior disc height, neuroforaminal area, and the neuroforaminal volume. Fusion rates and clinical results were also reviewed. RESULTS: Posterior disc height (mm), neuroforaminal area (mm2) and neuroforaminal volume (mm3) were increased and maintained during the follow-up period. Radiological fusion was noted in 17 levels (85%) at a postoperative 1 year. Satisfactory clinical results were also obtained in 17 levels (85%). CONCLUSION: Anterior interbody fusion using a horizontal cylinder cage might be an effective method in the surgical treatment of degenerative lumbar spine or secondary segmental lumbar instability.
Decompression ; Follow-Up Studies ; Humans ; Spine*

STATEMENT OF PROBLEM: Platelet-rich plasma(PRP) is well known to be very effective method to stimulate and accelerate the healing of bone and soft tissue. However, there are few reports which deal with the mechanisms of the PRP on the activation of the osteoblasts. PURPOSE: This study was aimed to investigate the effect of growth factors in PRP on the activity of osteoblasts. MATERIAL AND METHOD: To evaluate the effect on human, human osteoblast cell line was cultured. PRP was extracted from the blood of a healthy volunteer. Using the recombinant growth factors of PDGF, TGF-beta, IGF-1, bFGF which are mainly found at bone matrix and their neutralizing antibody, the effect of PRP on the attachment and proliferation of osteoblasts was evaluated. To evaluate the autocrine and paracrine effects, conditioned media(CM) of PRP was made and compared with PRP. By the western blot analysis, the expression of growth factors in PRP, CM was examined. Cell morphology was compared by the light microscope. RESULTS: 1) The effects of CM on osteoblast were similar to the effects of PRP. 2) PRP, CM, recombinant TGF-beta, bFGF, IGF-1 showed significantly higher cellular attachment than control(P<0.05) in the cell attachment assay. In the cell proliferation assay, PRP, CM, recombinant TGF-beta, IGF-1, bFGF, PDGF increased significantly cell proliferation(P<0.01). Among the recombinant growth factors, IGF-1 showed the highest cellular attachment and proliferation. 3) In the western blot assay, bFGF, IGF-1, PDGF were equally expressed in PRP and CM. 4) The attachment of osteoblast cell decreased significantly after the addition of neutralizing antibody against TGF-beta, IGF-1(P<0.05). In the cell proliferation assay, the addition of neutralizing antibody against TGF-beta, bFGF, PDGF, IGF-1 decreased significantly the cellular proliferation(P<0.05). The amount of decreasing in the cell attachment and proliferation is the highest in ab-IGF-1. 5) The cells in control group were flattened and elongated with a few cellular processes in the a light microscope. But, the cells appeared as spherical, plump cells with well developed cellular processes in experimental groups. The cells in PRP and CM had more prominent developed features than recombinant growth factor groups. CONCLUSIONS: These findings imply that PRP maximize the cellular activity in early healing period using the synergistic effect, autocrine, paracrine effects of growth factors and increase the rate and degree of bone formation.
Antibodies, Neutralizing ; Blotting, Western ; Bone Matrix ; Cell Line* ; Cell Proliferation ; Culture Media, Conditioned ; Healthy Volunteers ; Humans ; Insulin-Like Growth Factor I ; Intercellular Signaling Peptides and Proteins* ; Osteoblasts* ; Osteogenesis ; Platelet-Rich Plasma* ; Transforming Growth Factor beta

STATEMENT OF PROBLEMS: The precision of fit between the bearing surfaces of implant abutments and the prosthesis framework has been considered fundamental to implant prosthodontic protocol. PURPOSE: The study aimed to investigate the effect of laboratory procedure on the dimensional accuracy of cast implant bars. MATERIAL AND METHODS: Thirty implant bars were fabricated on a metal master model. The gap distances were measured at the right implant abutment replica-gold cylinder interface after casting procedure. The bar length data of precasting and postcasting state were collected and analyzed. RESULTS: The mean gap distance found after casting was 106.3 micrometer for buccal side, 122.1 micrometer for distal side and 117.1 micrometer for the lingual side. The mean bar length was 17964.7 micrometer at precasting measurement, 17891.6 micrometer at postcasting measurement. The mean change of bar length was - 73.1 micrometer. CONCLUSION: Even though the techniques used in this study strictly followed the guidelines established in the literature, the 30 cast implant bars evaluated all yielded gap distances that were beyond acceptable accuracy. There was a statistically significant difference between precasting and postcasting bar length (P<0.01). There was a decreasing tendency in bar length after casting procedure. It was necessary to correct this dimensional change from laboratory procedure by some corrective methods.
Prostheses and Implants ; Prosthodontics