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Biomedical subjects

K G Lee

Publications and source records attributed to K G Lee.

At least 19 recordsLinked to original sources
PubMed2005

Coupling of surface plasmon polaritons and light in metallic nanoslits.

We clarify the nature of coupling between surface plasmon polaritons (SPP) and transmitted light in metallic nanoslit structures. The coupling strength is found to be the product of the geometric opening ratio, the aperture momentum, and the Fabry-Perot factor. We determine the effective coupling, which includes corrections due to other SPPs, and show that this effective coupling causes enhanced transmission with redshifted or blueshifted transmission peaks. Without coupling, SPP is proven to suppress transmission due to the equipartition of diffraction orders. These results show good agreement with experiment.

Journal Article↗
PubMed2002

Coherent optical phonon oscillations in bulk GaN excited by far below the band gap photons.

We report on generation of coherent optical phonon oscillations in 150 microm thick bulk GaN. With photon energy far below the band gap, the generation mechanisms of coherent phonon modes of A1(LO), high- and low-frequency E2 are revealed to be the impulsive stimulated Raman scattering. We find that one among the two degenerate E2 modes is selectively detected with a proper choice of probe polarization. Dephasing times range from 1.5 to 70 ps for different modes, and phonon-three-photon absorbed carrier interactions are compared between the A1(LO) and the E2 mode.

Journal Article↗
PubMed2001

In vitro morphogenesis of amphibian erythroblasts.

Non-mammalian vertebrate erythrocytes are flattened nucleated ellipsoids containing marginal bands (MBs) of microtubules that assemble during cellular morphogenesis. Earlier work suggested that pointed erythroid cells containing pointed MBs were intermediate stages in terminal differentiation, rather than aberrant forms, but direct evidence was lacking. Here we report on morphogenesis in individual post-cytokinetic amphibian erythroblasts in culture. Daughter cells remained adjacent in pairs, and developed pointed morphology over 1-2 h in the following sequence: (a) ends opposite the cytokinetic furrow became pointed, producing a spheroidal singly-pointed stage; (b) furrow ends usually became pointed, yielding doubly-pointed cells; (c) furrow-end points disappeared, producing a second singly-pointed stage that was flattening. Over a longer term, the single points sometimes disappeared, yielding a flattened discoid. These observations support the hypothesis that pointed cells are normal intermediates in a biogenetic program in which post-mitotic centrosomes organize MBs while occupying the singly-pointed ends of differentiating erythroblasts.

Ambystoma↗
PubMed2001

Inhibition of malonaldehyde formation from blood plasma oxidation by aroma extracts and aroma components isolated from clove and eucalyptus.

The inhibitory effect of aroma extracts isolated from clove buds [Syzygium aromaticum (L.) Merr. et Perry] and eucalyptus leaves (Eucalyptus polyanthemos Schauer) on malonaldehyde (MA) formation from horse blood plasma oxidized with Fenton's reagent was determined by gas chromatography. Aroma chemicals such as eugenol, thymol and benzyl alcohol, identified in the aroma extracts, were examined for their inhibitory effect on the same system. Between the two aroma extracts tested, clove exhibited the most potent antioxidant activities. Extracts of eucalyptus and clove inhibited MA formation by 23 and 48%, respectively, at the level of 400 microg/ml, whereas, alpha-tocopherol and BHT inhibited MA formation by 52 and 70%, respectively, at the same level. Eugenol, thymol and benzyl alcohol inhibited MA formation by 57, 43 and 32%, respectively, at the level of 400 microg/ml.

Animals↗
PubMed2001

Studies of the central neural pathways to the stomach and Zusanli (ST36).

The purpose of this morphological study was to investigate the relation between the meridian, meridian points and viscera using neuroanatomical tracers. The common locations of the spinal cord and brain projecting to the stomach and Zusanli were observed following injection of CTB (cholera toxin B subunit) and pseudorabies viruses (PRV-Ba, Bartha strain and PRV-Ba-Gal, galactosidase insertion) into the stomach and Zusanli (ST36). After 4-5 days of survival following injection into twelve rats, they were perfused, and their spinal cords and brains were frozen sectioned (30 microm). These sections were stained by X-gal histochemical, CTB and PRV-Ba immunohistochemical staining methods, and examined with the light microscope. The results were as follows: Commonly labeled medulla oblongata regions were dorsal motor nucleus of vagus nerve (DMV), nucleus tractus solitarius (NTS) and area postrema (AP) following injection of CTB and PRV-Ba-Gal into stomach and Zusanli, respectively. In the spinal cord, commonly labeled neurons were found in thoracic, lumbar and sacral spinal segments. Densely labeled areas were found in lamina IV, V, VII (intermediolateral nucleus) and X of the spinal cord. In the brain, commonly labeled neurons were found in the Al noradrenalin cells/Cl adrenalin cells/caudoventrolateral reticular nucleus, dorsal motor nucleus of vagus nerve, nucleus tractus solitarius, area postrema, raphe obscurus nucleus, raphe pallidus nucleus, raphe magnus nucleus, gigantocellular nucleus, locus coeruleus, parabrachial nucleus, Kolliker-Fuse nucleus, A5 cell group, central gray matter, paraventricular hypothalamic nucleus, lateral hypothalamic nucleus, retrochiasmatic hypothalamic nucleus, bed nucleus of stria terminalis and amygdaloid nucleus. Thus central autonomic center project both to the stomach and Zusanli. These morphological results suggest that there is a commonality of CNS cell groups in brain controlling stomach (viscera) and Zusanli (limb).

Acupuncture Points↗
PubMed2001

Mucinous cystadenoma coexisting with stromal tumor with minor sex-cord elements of the ovary: a case report.

Mucinous neoplasms occur rarely in association with cystic teratoma, Sertoli-Leydig cell tumor, granulosa cell tumor or carcinoid tumor. Several cases of an ovarian stromal tumor with minor sex-cord elements have been reported in the literatures. However, there has been no report about an ovarian mucinous neoplasm coexisting with a stromal tumor with sex-cord elements yet. We report a case of an ovarian neoplasm composed of both mucinous cystadenoma and stromal tumor with minor sex-cord elements in a 58-yr-old female. The ovary including the mass measured 5 cm in size. On section, it revealed an unilocular cyst (4.5 cm in diameter) filled with mucinous fluid. There was a round, yellow, solid nodule, 1.5 cm in diameter within the wall. Microscopically, the cyst was lined by a single layer of endocervical mucinous epithelium and the nodule was composed of spindle cells showing an intersecting and whorled arrangement. There were cell nests showing polygonal shape with abundant cytoplasm among the spindle cells. They showed immunoreactivity for inhibin and did not have any connection with the adjacent mucinous epithelium. Therefore, we interpret the mucinous cystadenoma as having arisen de novo.

Cystadenoma, Mucinous↗
PubMed2000

Antioxidative activities of aroma extracts isolated from natural plants.

Natural leaves and flowers containing numerous aroma chemicals are widely used in aromatherapy since ancient times. In addition to their pleasant smells, aroma chemicals might have some beneficial health effects. Aroma extracts, isolated from coffee beans, soybeans, and mung beans by steam distillation under mild conditions (55 degrees C and 85 mm Hg) were examined for their antioxidative activities. The inhibitory effect of these extracts toward hexanal/hexanoic acid conversion was measured in the testing solution over prolonged time periods. The inhibitory effects of these extracts toward malonaldehyde formation from lipids oxidized by Fenton's reagent were also measured. The antioxidative activity of these extracts, in particular coffee bean extract, was consistent with that of BHT or alpha-tocopherol (vitamin E). Soybeans and mung beans extract contained maltol, which inhibits hexanal oxidation significantly. Eugenol, which is one of the major constituents of mung bean extract, exhibited potent antioxidative activity in an aldehyde/carboxylic acid assay. Antioxidants such as eugenol and maltol may play an important role in the pharmaceutical activities of natural plant extracts used for aromatherapy.

Aldehydes↗
PubMed2000

Determination of antioxidant properties of aroma extracts from various beans.

Aroma extracts from fresh soybeans, mung beans, kidney beans, and azuki beans were prepared using simultaneous steam distillation and solvent extraction (SDE) under mild conditions (55 degrees C and 95 mmHg). Extracts were examined for antioxidative activities in two different assays. The aroma extracts isolated from all beans inhibited the oxidation of hexanal for nearly one month at a level of 250 microL/mL. Mung bean and soybean extracts inhibited malonaldehyde (MA) formation from cod-liver oil by 86% and 88%, respectively, at the 250 microL/mL level. Azuki and kidney bean extracts inhibited MA formation from cod-liver oil by 76% and 53%, respectively, at the 250 microL/mL level. The antioxidative activities of mung bean and soybean extracts were comparable with that of the natural antioxidant, alpha-tocopherol (vitamin E).

Antioxidants↗
PubMed2000

Antioxidant properties of aroma compounds isolated from soybeans and mung beans.

Aroma compounds contained in the extracts of soybean and mung bean that possess antioxidant activity were identified by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). The major aroma constituents of soybeans were 1-octen-3-ol (13.699 ppm), maltol (1.662 ppm), phenylethyl alcohol (1.474 ppm), hexanol (1.430 ppm), and gamma-butyrolactone (1.370 ppm). The major aroma constituents of mung beans were hexanol (3.234 ppm), benzyl alcohol (2.060 ppm), gamma-butyrolactone (1.857 ppm), 2-methyl-2-propenal (1. 633 ppm), and pentanol (1.363 ppm). The major aroma chemicals of soybeans and mung beans were examined for antioxidative activities in two different assays. Eugenol, maltol, benzyl alcohol, and 1-octen-3-ol showed potent antioxidative activities in two different assays. Eugenol, maltol, benzyl alcohol, and 1-octen-3-ol inhibited the oxidation of hexanal by 100%, 93%, 84%, and 32%, respectively, for a period of 40 days at the 500 microg/mL level. Eugenol, maltol, benzyl alcohol, and 1-octen-3-ol inhibited malonaldehyde (MA) formation from cod liver oil by 91%, 78%, 78%, and 78%, respectively, at the 160 microg/mL level. The antioxidative activity of eugenol was comparable to that of the natural antioxidant alpha-tocopherol (vitamin E).

Antioxidants↗
PubMed2000

The biomechanics of rapid maxillary sutural expansion.

Micro-displacements (fringe patterns) in the bones of the craniofacial complex as seen through laser holography during midpalatal sutural expansion with the Hyrax appliance are used to define the centers of rotation of the maxillary halves in both the frontal and occlusal views. Biomechanical analyses of the maxillary expansion force system are concomitant with the holographic findings and strongly suggest that the stainless steel wires joining the teeth to any expansion device be of the largest diameter possible. In addition, in the case of the Hyrax expansion device, it is recommended that the manufacturer increase the diameter of the activating screw as well as those of the 2 adjacent wire guides. And, importantly, the use of acrylic as a structural member to join the teeth to a sutural expansion device should be avoided if tipping of the maxillary halves is to be minimized, as the acrylic lacks sufficient rigidity.

Acrylic Resins↗
PubMed2000

The effects of Pva/chitosan/fibroin (PCF)-blended spongy sheets on wound healing in rats.

The effects of poly vinyl alcohol (PVA)/Chitosan/Fibroin (PCF)-blended sponge on wound healing in rats were investigated. We excised the skin of a rat, including the dermis, approximately 2 x 2 cm in size. The wound was covered with PCF-blended spongy sheets. The spongy sheets absorbed the exudate, and gained flexibility and softness. Histopathological inspection of the wound 12 d later showed an increase of vascular ingrowth and the absence of inflammatory cells. Regeneration of the skin around the wound was faster than that of the control. We also tested wound healing effects of PVA, Chitosan and Fibroin, alone or in various combinations. Wound healing was accelerated in the order of PCF-blended sponge>Chitosan/Fibroin (CF)-blended sponge>Fibroin (F) sponge > PVA/Chitosan-blended sponge (PC) > Chitosan (C) sponge.

Animals↗
PubMed1999

A reexamination of various extraoral appliances in light of recent research findings.

The location of the center of resistance of the dentomaxillary complex has recently been identified more accurately than before. Based on this new finding, various modifications of the common facebow are presented for use in protraction therapy. Clinical applications for specific treatment objectives are also reviewed. Orthopedic and biomechanical implications of various standard retraction type extraoral appliances are also analyzed.

Biomechanical Phenomena↗
PubMed1998

Detection of human papillomavirus in warty carcinoma of the uterine cervix: comparison of immunohistochemistry, in situ hybridization and in situ polymerase chain reaction methods.

Warty carcinoma of the uterine cervix is a very rare specific variant of invasive squamous cell carcinoma, usually described as a hybrid feature of condyloma with invasive squamous cell carcinoma. Besides having the koilocytes and maturation of squamous epithelium, there is unequivocal stromal invasion. The feathery surface seems to be characteristic of warty carcinoma, differentiating it from condylomata acuminata or verrucous carcinoma. Using in situ polymerase chain reaction (IS-PCR) and in situ hybridization (ISH) as well as an immunohistochemical technique (IHC), we determined the amplification and expression of several human papilloma virus (HPV) types (6, 11, 33, 16 and 18) in nine warty carcinomas of the uterine cervix. We found amplified HPV predominantly in the nuclei of the feathery surface in all cases only when IS-PCR was applied, while it was detected only in five (55.6%) or six cases (66.7%) by conventional IHC or ISH, respectively. We found multiple types in the same lesion in six cases (66.7%) by IS-PCR, in comparison with ISH which detected a lower incidence (22.2%). This finding of coinfection is more consistent with that seen in low-grade squamous intraepithelial lesions (LSILs) of the uterine cervix than in high SIL. It is important to be aware of these distinct lesions in postmenopausal women with their characteristic feathery and thin surface, as well as a hybrid form of exophytic condyloma and stromal invasion, and frequent coinfection of multiple different HPVs as a type of LSILs.

Adult↗
PubMed1998

Allergic and immunologic profile of symptomatic Persian Gulf War veterans.

BACKGROUND: Persian Gulf War veterans have been enrolled in the Veterans Administration Persian Gulf Health Registry for evaluation of unexplained symptoms and illnesses. The allergy and immunology division at the West Los Angeles Veterans Administration Medical Center evaluated 20 consecutive symptomatic Persian Gulf War veterans. OBJECTIVE: The purpose of this study was to examine the immunologic profiles of symptomatic Persian Gulf War Veterans. METHODS: A detailed history was obtained that included duties/responsibilities, length of time in the Persian Gulf, location, and exposures during the Gulf War. A complete physical examination was performed, with extensive laboratory testing and immediate and delayed hypersensitivity skin testing. Data from these Persian Gulf War Veterans were compared with a control population consisting of 44 non-Persian Gulf War veterans enrolled in our allergy and immunology clinic. Presenting allergic symptoms, presence of atopy, and total serum IgE levels were compared. RESULTS: Persian Gulf study patients and registry patients had a broad spectrum of nonspecific symptoms as compared with allergy clinic control patients who had dermatologic and respiratory symptoms. Persian Gulf study patients with allergy symptoms had a higher mean IgE level (88.7 IU/mL) than Persian Gulf study patients without allergy symptoms (47.5 IU/mL). Persian Gulf study patients with positive skin tests had a higher mean IgE level (161.5 IU/mL) than Persian Gulf study patients with negative skin tests (22.3 IU/mL). Laboratory data showed no significant immune abnormalities. CONCLUSION: Our study showed that 20 Persian Gulf veterans with a multitude of nonspecific symptoms had no immune abnormality. Mean IgE levels and eosinophil counts correlated with atopic state and reported allergy symptoms.

Adult↗
PubMed1998

Malignant eccrine spiradenoma with florid squamous differentiation.

Malignant eccrine spiradenoma (MES) is an exceedingly rare neoplasm of cutaneous adnexal origin. To date, 31 cases have been documented in the literature. We herein report an additional case of MES that arose in longstanding eccrine spiradenoma (ES). A 54-year-old woman was seen for a bluish nodular mass on the right flank that previously had been stable for 7 to 8 years and had recently increased in size and become tender. The excised mass (2.8 x 2.5 x 2.5 cm) had no attachment to the overlying epidermis. Microscopically, 2 to 3 sharply demarcated lobules were surrounded by a markedly thickened and hyalinized fibrous capsule. Of the lesion removed, approximately 20% of the tumor showed typical histologic features of benign ES. In the remaining malignant areas, the typical configuration of benign counterpart, consisting of peripheral rows of small dark basaloid cells and central layers of large pale cells partially forming lumina, was replaced with a massive solid proliferation of large pale cells showing nuclear pleomorphism, prominent nucleoli, increased mitotic activity (reaching 12/10 HPF) and loss of PAS-positive basement membrane. There were multiple foci of florid squamous differentiation in the malignant portion. Cytokeratin, focally S-100 and EMA were expressed in large pale cells, whereas alpha smooth muscle actin and S-100 were positive in small dark basaloid cells. Focal reactivity of CEA and EMA was found in the central lumina. P53 was not expressed in benign areas, whilst in malignant areas an occasional nuclear reaction was disclosed.

Adenoma, Sweat Gland↗
PubMed1997

A study of holographic interferometry on the initial reaction of maxillofacial complex during protraction.

Most extraoral appliances used for protracting small or retropositioned maxilla do not allow for variations in the point of force application or in its direction. This variation may be necessary to control vertical, anteroposterior, as well as transverse effects. The purpose of this study was to investigate the initial reaction of the maxillofacial complex according to force magnitude, force direction, and point of force application. For this purpose, an antenna-type modified protraction headgear was tested with double exposure holographic interferometry on a dry human skull with well-aligned upper teeth. Fringe patterns of each protraction condition were compared and analyzed. In most cases, upward rotation of the anterior portion of the maxilla changed to translation, or to downward rotation, as force direction was changed from parallel to the occlusal plane to 20 degrees downward to the occlusal plane. Furthermore, a 500 gm force applied 15 mm above and directed 20 degrees below the occlusal plane produced a translation of the maxillary complex, indicated by a typical circular fringe pattern on the holographic plate, which represents the center of resistance of the maxilla. In most cases, with all force variables tested, a protraction of the maxilla with palatal expansion was more effective in producing translation of the maxilla than was protraction without palatal expansion. By varying force magnitude, force direction and point of force application with maxillary protraction, the amount of maxillary rotation and translation might be controlled.

Adult↗
PubMed1993

Diagnosis of cervical tuberculous lymphadenitis with fine needle aspiration biopsy and cytologic examination under ultrasonographic guides.

The efficacy of the fine needle aspiration biopsy and cytological examination (FNABC) under ultrasonographic (US) guides for the diagnosis of cervical tuberculous lymphadenitis was assessed. In one hundred and one patients with a neck mass or masses, tuberculous lymphadenitis has been proved by FNABC. US disclosed the physical characteristics of the masses: All the cases that involved two or more lymph nodes were multiple lesions. Eighty lesions (79.1%) were multiregional, and in 19 cases (18.8%), bilateral neck was involved. The posterior triangle of the neck was the most prevalent site (N = 69, 68.3%). Ninety two cases (90.9%) were hypoechoic lesions and 9 (9.1%) showed mixed echo patterns. There was no hyperechoic lesion (p < 0.001). The sensitivity of FNABC was 77.2% and the specificity was 99.0%. The diagnostic accuracy was 85.0%. There was no complication during the procedure. FNABC for the diagnosis of cervical tuberculous lymphadenitis is a safe, convenient procedure and has a relatively high specificity. The limitation of FNABC, the low sensitivity, seemed to be compensated by US examinations.

Biopsy, Needle↗