Biomedical subjects

S M Kwon

Publications and source records attributed to S M Kwon.

4 recordsLinked to original sources

PubMed2002

Spine needle biopsy simulator using visual and force feedback.

OBJECTIVE: Biopsy with an inserted needle is an important procedure for lesion detection in the spine, but is difficult to perform due to the presence of many critical organs near the spine. This article presents a spine needle biopsy simulator, based on visual and force feedback, which can be used to plan the optimal path of a needle and to practice the procedure without risk. MATERIALS AND METHODS: The simulator is composed of a 3D human model, a visual-feedback component, a force-feedback component, and an evaluation module. The human model is based on 3D CT data. The visual-feedback component provides an oblique section, multiplanar reformatting images, and a volume-rendered image. Of these, the oblique section display is very useful for planning a 3D path for the needle. During simulation, the force-feedback component generates and provides realistic forces acting on the biopsy needle in real time by synchronizing them to visual feedback. After each simulation, the evaluation module provides a performance analysis for the trainee. RESULTS: For an XCT abdomen volume data set of 256 x 256 x 256, the update rate of image rendering due to needle movement is over 25 Hz, with a force-feedback rate of 1 kHz. This performance proved to be good enough for the trainee to learn the relationship between visual and force feedback. CONCLUSIONS: The simulator is useful for the planning of and training in complicated 3D spine needle biopsy procedures. It may be used as an educational tool for beginners, a practice tool to increase expertise, or a test bed for new procedures.

Algorithms↗

PubMed2001

Development of rat prostatitis model by oral administration of isoflavone and its characteristics.

Inflammation of the prostate can be induced experimentally in rats by the subcutaneous administration of estrogen. However, it is usually achieved at the price of some alteration in the sex steroid hormone balance and morphological changes in the prostate. In this study, a soy-extracted isoflavone mixture with weak estrogenic activity was administered orally in an attempt to induce prostatitis in a more physiologic way and to characterize the inflammation induced. A total of 36 male Sprague-Dawley rats, 8 weeks old, were divided into 2 groups. The control group was fed with only an AIN-76A diet containing no detectable phytoestrogen and the experimental group was fed with AIN-76A and a soy- extracted isoflavone mixture (genistein 60.0% and daidzein 19.6%), 300 mg/kg body weight for 9 weeks. The sequential body weight and prostate weight at necropsy were measured. A histologic examination and histomorphometry assessed the changes in the prostate. The serum concentrations of testosterone and dihydrotestosterone were measured to estimate the effects on the androgen level. Intraprostatic concentrations of genistein and daidzein were measured by gas chromatography/ mass spectroscopy (GC/MS). While no sign of prostate inflammation was apparent in the control group, severe inflammatory changes in the stroma, increased epithelial detachment and inflammatory exudates within the glandular lumen of the dorsolateral prostate were observed in more than 80%(15/18) of the experimental group. However, there was no significant difference in the ventral prostate between the two groups. The daidzein and genistein concentrations in both the lateral and ventral prostates were significantly higher in the experimental group than in the control group where no isoflavone was detectable. In addition, the concentrations were much higher in the dorsolateral than in the ventral prostate. Although the body weight gain was not consistent in the experimental group, there were no significant differences in the prostate weight and serum androgen level between groups. In summary, when a soy-extracted genistein and daidzein-rich isoflavone mixture was administered orally into rats, prostatic inflammation with characteristic lobe specificity developed. The present method of inducing prostatitis seems to be a more physiologic than an estrogen-induced experimental model, and sequential pharmacokinetic studies might help in establishing this model as a more valuable tool in assisting future research in this field.

Administration, Oral↗

PubMed1999

Simultaneous determination of anions and cations by ion-exclusion chromatography-cation-exchange chromatography with tartaric acid/18-crown-6 as eluent.

Ion-exclusion chromatography-cation-exchange chromatography was developed for the simultaneous separation of common inorganic anions and cations (Cl-, NO3- and SO4(2-); Na+, NH4+, K+, Mg2+ and Ca2+) on a weakly acidic cation-exchange column by elution with weak acid. Generally, the resolution among these monovalent cations was only moderate, thereby hindering the determination of these analytes in natural-water samples. Therefore, 18-crown-6 was added to the eluent to improve the resolution. A good separation of these anions and cations on a weakly acidic cation-exchange column was achieved in 30 min by elution with 5 mM tartaric acid/6 mM 18-crown-6/methanol-water (7.5:92.5). The ion-exclusion chromatography-cation-exchange chromatography method developed here was successfully applied to the separation of major anions and cations in an environmental water sample.

Anions↗

PubMed1998

Reduced need for alveolar bone grafting by presurgical orthopedics and primary gingivoperiosteoplasty.

OBJECTIVE: The purpose of this study was to evaluate if narrowing and approximation of the alveolar cleft through presurgical alveolar molding followed by gingivoperiosteoplasty (GPP) at the time of lip repair reduces the need for a bone-grafting procedure. DESIGN: This was a retrospective blind study of patients with unilateral or bilateral alveolar clefts who underwent presurgical infant alveolar molding and GPP by a single surgeon. Alveolar bone formation was assessed prior to the eruption of the maxillary lateral incisor or canine by clinical examination, panoramic and periapical radiographs, and/or a dental CT scan. The criterion for bone grafting was inadequate bone stock to permit the eruption and maintenance of the permanent dentition. SETTING: This study was performed at the Institute of Reconstructive Plastic Surgery by the members of the Cleft Palate Team. PATIENTS: All patients with unilateral (n = 16) or bilateral (n = 2) alveolar clefts who underwent presurgical infant alveolar molding and GPP by a single surgeon from 1985 to 1988 were studied. The control population consisted of all alveolar cleft patients (n = 14) who did not undergo alveolar modeling or GPP during the same time period. INTERVENTIONS: Presurgical alveolar modeling was performed with an intraoral acrylic molding plate. This plate was modified on a weekly basis to align the alveolar segments and close the alveolar gap. The surgical intervention consisted of a modified Millard GPP. MAIN OUTCOME MEASURES: The primary study outcome measure was the elimination of the need for a secondary bone graft in patients who underwent presurgical alveolar molding and GPP. RESULTS: Of the 20 sites in the 18 patients who underwent GPP, 12 sites did not require an alveolar bone graft. Of the 8 sites requiring a bone graft, 4 presented minimal bony defects. All 14 patients in the control group required bone grafts. CONCLUSIONS: In this series of 20 alveolar cleft sites treated with presurgical orthopedics and GPP, 60% did not need a secondary alveolar bone graft in the mixed dentition.

Alveolar Process↗