Biomedical subjects

K Hwang

Publications and source records attributed to K Hwang.

At least 37 records · Page 2Linked to original sources

PubMed2000

Brachycephaly and external pressure.

Browsing through some literatures, I happened to find out some records on the rite of imitation of the child's head to brachycephaly. In 1976, two skulls showing extraordinary forms were excavated out of an ancient tomb at Yean village of Daedong township in Kimhae County in Kyungnam Province, the Republic of Korea. The deformation in Yean village is judged to be an intentional frontal flattening. The frontal bone of deformed individuals is remarkably flattened by a primary deforming force. The parietal bone expands laterally and superoposteriorly as a major compensatory growth. The lambdoid or occipital flattening induced by the counterforce is light and unstable. In the facial skeleton, the maxilla shifts downward as a minor compensatory growth. These findings might be substantially correspondent to the custom in the southern area of Korea in the 4th century A.D. paragraphed by Han chuan of Wei-dynasty record, History of the Three Kingdoms. It described that the people gave a pressure onto the child's forehead with stones in order to mold it for preference. Flatheaded meant "free" among the Chinook and Salish tribes of American Indians. Babies of slaves were denied the year-long beauty treatment--a board tied to the infants' padded skull--that permanently flattened the foreheads of tribal members. Referring to these records, I presume that brachycephaly can be induced by direct extrinsic pressure at least until the soft infant's head gets hard.

Culture↗

PubMed2000

Interface between titanium miniplate/screw and human calvaria.

This study demonstrates interfacial changes of titanium miniplate/screw with normal calvaria and nonvascularized calvarial bone graft ensued from craniectomy in a 53-year-old female. In 18 months after operation, a right parietal bone containing an L-shaped miniplate with screws, 5 mm long and 2 mm in external diameter, was harvested, fixed, and embedded in methylmetacrylate. Fifteen micrometer thick sections were made by an EXAKT cutting-grinding system (Exakt Company, Hamburg, Germany), and reviewed under the bright field light microscope. The mean of the bone-contacting surface ratio (BCSR) in six screwed bone was 64.1%; 69.3% in normal bone, and 60.4% in grafted bone. The trabecular bone areas in 10 x 5 mm (50 mm2) rectangular area of diploe surrounding the screws was 43.02 mm2; 45.25 mm2 in normal calvaria; and 41.82 mm2 in grafted bone. The mean Ca/P peak-height ratio of the plated and screwed calvaria was 1.47 in a 9 mm wide zone around each screw; 1.37 in normal calvaria; and 1.51 in grafted calvaria. We concede that the effect of direct contact of titanium with screws onto the bone is as much as an osseous integration (osseointegration).

Bone Plates↗

PubMed2000

Cutaneous sinus tract from remaining tooth fragment of edentulous maxilla.

Cutaneous sinus tract of dental origin usually arises from chronic dental infections. These tracts usually appear as suppurative lesions of the chin or neck. Because many patients with this lesion do not have any complaints of oral symptoms, these lesions are often diagnosed incorrectly and overlooked, and are also treated ineffectively. A case of an unusual presentation of a chronic suppurative granuloma on nasolabial fold, which originated from the remaining tooth fragment of edentulous maxilla, is reported. Treatment with removal of the tooth fragment as well as the sinus tract resulted in complete healing of the lesion. This report emphasizes the importance of awareness of the possible dental origin of facial sinuses, despite their unusual location.

Chronic Disease↗

PubMed2000

Intraosseous hemangioma of the orbit.

Intraosseous hemangiomas of the orbit are very rare tumors. A case of cavernous hemangioma of the superolateral orbital rim is presented. A 45-year-old woman had a 1-year history of progressive swelling in the left lateral brow area. A computed tomography scan showed a well-marginated osteolytic lesion on the frontal bone near the frontozygomatic suture. The lesion was thought to be fibrous dysplasia, and the patient underwent tumor excision. The histological diagnosis was cavernous hemangioma. Cavernous spaces were filled with blood between the bony trabeculae. The spaces were lined by benign flattened endothelium. Intraosseous hemangioma should be suspected when a patient presents with an enlarging mass fixed to bone around the orbit.

Cranial Sutures↗

PubMed2000

Pneumosinus dilatans multiplex, mental retardation, and facial deformity.

Pneumosinus dilatans is a term used to describe enlargement of one or more paranasal sinuses without radiological evidence of localized bone destruction, hyperostosis, or mucous-membrane thickening. To date, many cases have been reported that involved frontal, ethmoid, sphenoid, and maxillary sinus. However, no case has been reported that involved all paranasal sinuses. Our case involved mastoid air cells as well as all paranasal sinuses. It is named pneumosinus dilatans multiplex by us. This is the first case to be reported in English literature that has this syndromic condition of pneumosinus dilatans multiplex, mental retardation, and facial deformity.

Adult↗

PubMed2000

Chin augmentation with a bone graft from the mandibular region.

The prominent, square angles of the mandible are not generally considered an alluring virtue in Asian women because a square chin is thought to be masculine, and sunken cheeks are thought to be ill-fated. An oval, slender face is customarily preferred. A 28-year-old single woman requested reduction of the mandibular angle and concomitant chin augmentation. Each scalene triangular piece of the bone from both mandibular angles was carved and shaped like an obtuse triangle. One side of its surface was serrated to effect a curve, and the revision was fixed with a miniplate. The pieces were placed on top of each other, set on the symphysis menti, and were immobilized with screws. The excised fragments of the mandible were used as bone grafts to augment the chin during the same operation.

Adult↗

PubMed2000

Imaging of malignant lymphomas with F-18 FDG coincidence detection positron emission tomography.

PURPOSE: The authors evaluated the utility of F-18 fluorodeoxyglucose (FDG) coincidence detection (CoDe) positron emission tomography (PET) for staging, post-treatment evaluation, and follow-up assessment of patients with malignant lymphomas. MATERIALS AND METHODS: Fifty-eight patients with histologically proved malignant lymphomas (4 Hodgkin's disease, 54 non-Hodgkin's lymphoma) underwent CoDe PET using F-18 FDG. CoDe PET was performed using a dual-head gamma camera equipped with coincidence detection circuitry. Of the 87 CoDe PET studies, 26 were performed for staging, 38 for post-treatment evaluation, and 23 for follow-up evaluation of recurrence. The entire trunk, from the cervical to the inguinal regions, or selected regions were scanned with the patient in the supine position. No attenuation correction was made and reconstruction was performed using filtered back-projection rather than iterative reconstruction. CoDe PET findings were compared with corresponding results of computed tomographic (CT) and magnetic resonance imaging (MRI), tissue biopsy, or clinical follow-up. RESULTS: For staging, 52 sites were positive on CoDe PET or CT-MRI. CoDe PET detected 49 sites (94%), and CT-MRI showed 47 sites (90%). CoDe PET detected five more lymphomatous lesions and missed three lesions. For post-treatment evaluation, CoDe PET showed a positive predictive value of 100% and a negative predictive value of 83%, but the validated cases numbered only 11. For follow-up for recurrence, CoDe PET had a negative predictive value of 90%, but frequent false-positive findings were noted in the head and neck region as a result of underlying inflammatory changes. CONCLUSIONS: For staging, FDG CoDe PET alone without attenuation correction is not sensitive enough to be used as an independent imaging method, especially for small abdominal lesions. However, it appears to be an accurate method for assessing residual disease and for patient follow-up.

Adolescent↗

PubMed2000

Purification and embryotropic roles of tissue inhibitor of metalloproteinase-1 in development of "HanWoo" (Bos taurus coreanae) oocytes co-cultured with bovine oviduct epithelial cells.

This study was conducted to purify a tissue inhibitor of metalloproteinase (TIMP)-1 in a serum-free medium conditioned with bovine oviduct epithelial cells (BOEC) and to evaluate its effect on development of "HanWoo" (Bos taurus coreanae) embryos to the blastocyst stage. In the first study using SDS-PAGE electrophoresis, the presence of 32 kDa proteins, which contains TIMP-1, was detected in the medium conditioned with BOEC, and TIMP-1 was then purified from the medium by gel filtration and HPLC techniques. When examined TIMP-1 secretion, fluorescent foci indicating the secretion of TIMP-1 were found after stained BOEC with fluorescein isothiocyanate. In the next experiment, two-cell embryos derived from in vitro-fertilization were cultured in a serum-free medium, to which 0, 1.25, 2.5 or 5 microg/ml of purified TIMP-1 was supplemented. More (P<0.05) embryos developed to the morula and blastocyst stages after the addition of 2.5 microg/ml to culture medium than after no addition. In conclusion, our data indicate that BOEC secrete TIMP-1 and this glycoprotein promotes the prehatched development of "HanWoo" embryos derived from in vitro-fertilization.

Animals↗

PubMed1999

Alteration of the NAD+/NADH ratio in CHO cells by stable transfection with human cytosolic glycerol-3-phosphate dehydrogenase: resistance to oxidative stress.

The intracellular level of the NAD+/NADH ratio plays a vital role in sustaining and coordinating the catabolic reaction of the cell, and reflects the redox state of cytosol. Antioxidants play a role to protect cytosol and membrane from free radicals. This role of antioxidants involves sustaining cell viability and the procedure is thought to be regulated by the equilibrium of the redox state of the cell. However, there is very little known about how the NAD+/NADH level is set and changed. To alter the ratio, human NAD-dependent glycerol-3-phosphate dehydrogenase (cGPDH) cDNA was transfected stably in CHO dhfr- cells. When compared to parental CHO cells, cGPDH activities of the transfected cells were increased 8-12 fold, but the NAD+/NADH ratio was decreased. Specific growth rate of the transfected cells was similar to or slight lower than that of wild type CHO cells. Cell viability of the stable transformants against H2O2 was increased without change of either catalase or glutathione peroxidase activity. However, the increase of cell viability was correlated with the decrease of NAD+/NADH ratio in transfectants. From these results, it is suggested that the overexpression of cGPDH changes the NAD+/NADH ratio toward a decrease, and by this change in the redox state the cell confers more resistance against H2O2.

Animals↗

PubMed1999

Impact of nicotine on bone healing.

A limited number of experimental animal studies and in vitro data confirm that nicotine impairs bone healing, diminishes osteoblast function, causes autogenous bone graft morbidity, and decreases graft biomechanical properties. Therefore, our long-term goal is to develop an effective therapy to reverse the adverse impact of nicotine from tobacco products. However, before accomplishing this goal, we had to develop an animal model. Our hypotheses were nicotine administration preceding and following autogenous bone grafting adversely affected autograft incorporation and depressed donor site healing in a characterized animal wound model. Hypothesis testing was accomplished in bilateral, 4-mm diameter parietal bone defects prepared in 60 Long-Evans rats (male, 35-day-old). A 4-mm diameter disk of donor bone was removed from the left parietal bone and placed in the contralateral defect. The donor site served as a spontaneously healing bone wound. The rats were partitioned equally among three doses of nicotine administered orally in the drinking water (12.5, 25, and 50 mg/L). For each dose, the duration and sequence of nicotine treatment followed four courses, including no nicotine and designated combinations of nicotine administration and abatement prior to and following osseous surgery. Experimental sites were recovered on 14 and 28 days postsurgery, responses quantitated, and data analyzed by analysis of variance and post hoc statistics (p < or = 0.05). We developed a convenient and effective osseous model, and the results validated our hypothesis that nicotine negatively impacts on bone healing.

Animals↗

PubMed1999

Bone morphogenetic proteins: an update on basic biology and clinical relevance.

The regeneration of bone is a remarkable, complex physiological process, and BMPs are a formidable clinical tool to promote its regeneration. By defining roles played by BMPs in developmental biology and bone regeneration, significant progress has been made to identify cell-signaling molecules and their regulators. For example, the regulators of BMPs that include noggin, chordin, cerberus, dan, and gremlin may be harnessed as therapies to offset calcification encountered after total hip arthroplasties. Furthermore, exploiting BMPs and Smads may generate new therapeutic options for bone repair. Another compelling clinical consideration is the trans-acting factor osteoblast-specific factor-2, which can promote osteoblast differentiation. Moreover, the affiliation of osteoblast-specific factor-2 with heritable disorders merits exploration. A recognized daunting challenge includes a carrier/delivery system for the powerful morphogenetic therapeutic tools, as well as osteoprogenitor cells and intracellular transduction and transcriptional factors. In addition, the long-term effects of administering superphysiological doses of rhBMPs to patients must be assessed systematically. A new generation carrier/delivery system may be the answer to offset dosing liabilities as well as to provide residence for exogenous, BMP-receptive osteoprogenitor cells (111,112). The areas highlighted in this review offer fertile territory for thought and research to develop rational clinical treatments to promote bone regeneration and to understand some of the biological roles of BMPs.

Animals↗

PubMed1999

Barbarin as a new tyrosinase inhibitor from Barbarea orthocerus.

A tyrosinase inhibitor was isolated from the whole plant of Barbarea orthocerus Led. (Brassicaceae) by activity-guided fractionation, and identified as (R)-5-phenyl-2-oxazolidinethione (barbarin) by structural analysis followed by comparison with reported spectral data. The compound exhibited significant inhibitory effects on mushroom and murine tyrosinases at more than 1.6 x 10(-5) M. Barbarin exhibited IC50 values of 4.2 x 10(-5) M on mushroom tyrosinase and of 4.8 x 10(-5) M on murine tyrosinase. Kojic acid as a positive control exhibited IC50 values of 3.4 x 10(-5) M and 6.0 x 10(-5) M on mushroom and murine tyrosinases, respectively. Therefore, barbarin exhibited a similar level of inhibitory potency with kojic acid used as a positive control. In a kinetic study with various concentrations of L-dopa as the substrate, barbarin was identified as an uncompetitive inhibitor and kojic acid as a mixed inhibitor of both mushroom and murine tyrosinases. Barbarin exhibited KEIS values of 3.3 x 10(-5) M and 3.6 x 10(-5) M on mushroom and murine tyrosinases, respectively. Kojic acid exhibited KEIS and KEI values of 2.4 x 10(-5) M and 2.2 x 10(-5) M on mushroom tyrosinase and those of 8.9 x 10(-5) M and 7.2 x 10(-5) M on murine tyrosinase, respectively.

Animals↗

PubMed1999

Surgical anatomy of the orbit of Korean adults.

When operating in and around the orbit, the key to a successful result is precise anatomical localization. However, there is no precise study about the localization of vital orbital structures from reliable periorbital bony anatomy of the Korean adult. This study was constructed to give pertinent anatomical measurements to which the plastic and maxillofacial surgeon may refer. The 82 orbits obtained from 41 skulls of adult Koreans were measured with Vernier calipers and Marshac calipers. Superiorly, the supraorbital fissure was 40.0 +/- 2.5 mm from the supraorbital notch. Medially, the posterior ethmoidal foramen was 31.7 +/- 3.0 mm from the anterior lacrimal crest. Inferiorly, the infraorbital fissure where the infraorbital groove started was 26.4 +/- 2.6 mm from the infraorbital foramen. Laterally, the supraorbital fissure was 34.3 +/- 2.7 mm from the frontozygomatic suture. These distances are suggested as appropriate safe distances from each periorbital bony landmark. Dissection beyond that distance should be done with great caution.

Adult↗

PubMed1999

Attachment of the deep temporal fascia to the zygomatic arch: an anatomic study.

It is generally acknowledged that the superficial layer of the deep temporal fascia attaches to the lateral surface and its deep layer along the medial surface of the zygomatic arch. However, Ramírez asserts that the superficial and the deep layer of the deep temporal fascia fuse consistently approximately 1 cm above the upper ridge of the arch and attach to the outer surface of the arch, blending with the superficial fascia of the masseter muscle. In this study the authors clarify the precise anatomic relations between the fascia and the zygomatic arch. Coronal sections crossing the midpoint between the zygomaticotemporal suture and the tubercle of zygoma were observed grossly and histologically in 32 hemifaces from 16 Korean adult cadavers. This study demonstrates that the superficial and the deep layers of the deep temporal fascial fuse and insert onto the superior margin of the arch in 18 dissections (56%) and insert onto the superolateral surface in 14 dissections (44%). The contacting surface of the fused deep temporal fascia to the periosteum of the zygomatic arch is less than 2 mm. The following route is safer and is recommended for reaching the zygomatic arch region: Just above the split of the deep temporal fascia, a dissection is carried through the deep temporal fasica, continuing downward to the superior margin of the arch along the undersurface of the fascia. At this spot the periosteum of the arch is dissected.

Adult↗

PubMed1999

The thickness of the skull in Korean adults.

New instrumentation and techniques for skeletal fixation have been developed in response to concerns regarding variability of the skull base and the calvaria. The fear of intracranial penetration has limited the use of internal or external fixation to the skull base and the calvaria. Despite potential clinical usefulness, limited anthropometric data have been reported on the skull base and the calvaria. The purpose of this study was to measure the average thickness of various points of the skull base and the calvaria of Korean adults. Fifty-one Korean adult skull bases and calvaria, which were cut 2 cm above the supraorbital margin anteriorly and 2 cm above the inion posteriorly, were measured in this study. Thickness of 13 clinically important points were measured with a Teclock GM-21 Calipergauge (Teclock Co., Tokyo, Japan). The mean thickness of the two opposite sides were compared using paired t-tests. They did not differ significantly from the others except for three points. Frontal bone A (located 1 cm above the supraorbital margin and 1.5 cm lateral to the midline) was 6.35 +/- 2.88 mm, frontal bone B (located at the midpoint of the frontal midpoint and the frontoparietal suture on the cut edge) was 5.24 +/- 1.50 mm, frontal bone C (located at the midpoint of the vertex and frontal bone B) was 6.63 +/- 1.77 mm, the pterion was 3.19 +/- 0.85 mm, the midpoint of the squamous temporal was 1.96 +/- 0.65 mm, parietal bone A (located 1.5 cm below the middle meningeal groove) was 3.99 +/- 1.11 mm; parietal bones B and C (divided at the distances between the frontoparietal suture and the occipital midpoint with a ratio of 1:3 and 2:3 respectively on the cut edge) were 4.71 +/- 1.06 mm and 5.35 +/- 0.91 mm respectively, occipital bone A (located 1.5 cm posterolateral from the foramen magnum) was 2.31 +/- 1.00 mm, occipital bone B (located 1.5 cm lateral to the midline and 0.5 cm above the inion) was 5.41 +/- 1.50 mm, occipital bone C (located occipital to the midpoint and 2 cm above the inion) was 8.2 +/- 1.67 mm, the orbital roof was 1.37 +/- 1.08 mm, and the orbital lateral wall was 2.25 +/- 1.06 mm. The data give practical information for determining the position and depth for safe and effective internal or external fixation during craniofacial procedures.

Adult↗

PubMed1999

Reduction of zygomatic arch fracture using a towel clip.

The authors describe a simple technique for reducing zygomatic arch fractures with a towel clip. The orbital rim and zygomatic arch are outlined with a marking pen. The exact fracture site is then marked by palpation. The depressed fracture site is held with a towel clip and pulled outward gently. A clicking noise may be heard. The clip is then released. The contour of the zygomatic arch is compared with the other side. Using this technique the authors reduced 11 fractured zygomatic arches (arch only, displaced medially) in 11 patients and the results were satisfactory in all patients. The towel clip method is one procedure to reduce zygomatic arch fracture.

Adolescent↗

PubMed1999

Tenosynovial giant cell tumor of finger, localized type: a case report.

The authors report a typical case of tenosynovial giant cell tumor of the right middle finger of a 31-year-old man. Histologically, this tumor is characterized by a discrete proliferation of rounded synovial-like cells accompanied by a variable number of multinucleated giant cells, inflammatory cells, and xanthoma cells. Clinicopathologically, this tumor is a benign lesion that nonetheless possesses a capacity for local recurrence. Local excision with a small cuff of normal tissue is the treatment of choice in this tumor.

Adult↗

PubMed1998

An anatomical study of the junction of the orbital septum and the levator aponeurosis in Orientals.

The anatomical relationships of the orbital septum and levator aponeurosis has been studied in 40 eyelids subjected to blepharoplasty and corrective ptosis surgery by dissection in 10 cadavers and in histological sections. The orbital septum originates from the arcus marginalis of the frontal bone and consists of two layers. The whitish outer (superficial) layer, containing vertically running vessels, descends just inside the orbicularis oculi muscle to interdigitate with the levator aponeurosis with loose connective tissue, then disperses inferiorly. The inner (deep) layer follows the superficial one initially, then reflects at the levator aponeurosis and continues posteriorly with the levator sheath. We reconfirmed Whitnall's original description that the levator sheath thickens to form the superior transverse ligament runs continuously inferiorly anterior to the levator aponeurosis and forms the inner layer of the orbital septum. This detailed anatomical analysis should assist in performing upper eyelid surgery such as the Oriental double fold operation or levator resection.

Asian People↗