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Biomedical subjects

K Hwang

Publications and source records attributed to K Hwang.

52 records · Page 3Linked to original sources
PubMed1997

Thickness map of parietal bone in Korean adults.

The parietal bone remains the most common donor site for a bone graft in treating facial bone fractures, especially those involving orbital walls. Despite this potential clinical usefulness, anthropometric data on the parietal bone is lacking. Only one Korean and a few foreign studies report on its thickness, measured at two and three points of each of two parietal bones in a given subject, respectively. These studies, however, fall short of offering enough information for locating the optimal harvest point of the parietal bone for bone grafting. This study was thus aimed at constructing a thickness map that provides the mean parietal bone thickness at various points and determines the difference between them. Eighty-eight parietal bones were obtained from 44 Korean adult skulls for this study. Parietal bone thickness was measured at 15 points, spaced at regular intervals on each parietal bone of a given skull, using a Techlock GM 21 caliper gauge. The mean bone thickness at each of the 15 points of the bone and at the corresponding points of the opposite parietal bone was obtained in all skulls studied. The mean thickness at each point of measurement on two opposite parietal bones was compared using the paired Student's t test. Mean thickness did not differ significantly. The thickness in the same bone varied widely depending on the points of measurement. The thickest part, the posteromedial region of the parietal bone near the lambda, was 6.67 +/- 1.41 mm (mean +/- standard deviation [SD]) thick, and it became thinner toward the diagonal (anterolateral) direction, to the thinnest part, 4.73 +/- 1.19 mm (mean +/- SD) thick, near the pterion. It is hoped that our thickness map can serve as a practical guide for choosing an ideal site on the parietal bone for a bone graft of desired thickness.

Adult↗
PubMed1997

A thickness map of iliac bone of Korean adults.

The iliac bone is one of the most common donor sites for bone graft. Despite such potential and clinical usefulness, the anthropometric data on the iliac bone are lacking. The purpose of this study is to construct a thickness map that provides the mean iliac bone thickness of its various points and their differences. We studied 58 hip bones (from 23 males and 35 females) from Korean adults. We measured the iliac bone thickness at 26 points, which were positioned at regular intervals on each given iliac bone, using a Techlock GM 21 caliper gauge. The mean thickness of each measuring point of the male and the female, and of the right and the left, was compared with each other through paired t-test; the measurements did not differ significantly. From the anteriorposterior perspective, the region between anterior superior iliac spine (ASIS) and iliac tubercle was relatively thick. However, it became progressively thinner before it reached the sacroiliac articulation. It became thicker again toward the posterior superior iliac spine (PSIS), the thickest area. From the superoinferior perspective of superior iliac crest and inferior acetabulum, the thickness became inferiorly thinner in the anterior part between ASIS and iliac tuberosity. However, in the posterior part between the sacroiliac joint and PSIS, there was no significant difference of thickness. We hope that our thickness map can serve as a practical guide to the choice of an ideal site of the iliac bone for bone graft to obtain desired thickness.

Adult↗
PubMed1997

Distribution of hairs and sweat glands on the bodies of Korean adults: a morphometric study.

A morphometric study was made of the number of sweat glands and hairs per square centimeter of skin on different body regions of Korean adults. For this purpose, samples of skin from 30 body regions were obtained by punch biopsy from 74 cadavers of Korean adults. Serial transverse sections that extended through the papillary layer of the dermis were prepared in each case and subjected to routine histological staining. Sections of skin were examined under low magnification and the sweat ducts and hair follicles in each section were counted and recorded in terms of the number per square centimeter of skin. Arithmetic means and standard deviations for each region were also obtained for comparison of the densities of distribution. The soles (male) and the palms (female) were the regions of most densely distributed sweat glands while the mammary area in both sexes was the region of lowest density. Hairs were distributed most densely in the buccal region in males and on the mental (chin) region in females. The region of lowest density of hairs was the dorsum of the middle phalanx of the fingers in both sexes. Seven regions of the body exhibited significant sexual dimorphism in terms of the density of sweat glands while only four regions showed significant sexual dimorphism in terms of the density of hairs. Hairs appeared to be more densely distributed in the buccal regions of females than of males. However, the density of hairs in the dermis was not always proportional to the density of visible hairs.

Adult↗
PubMed1996

Intracellular distribution of selenium and the growth of mammary cells in culture.

Retention of Se in CMT-13 cells increased with an increase in the concentration of selenite in the incubation medium, the duration of exposure, and the density of the culture. The enhanced toxicity of selenite coincided with a proportional increase in Se in both the cytoplasm and nucleus. About 90% of the accumulated Se was isolated with cytoplasmic macromolecules. Increased nuclear Se retention correlated with increased cytoplasmic Se retention. Greater quantities of cytosolic Se-containing proteins (74, 55, 41, 34, and 28 kDa) and a nuclear Se-containing protein (56 kDa) were detected as the quantity of Se within CMT-13 cells increased. These findings suggest that cellular retention and distribution of Se are determinants of the degree of cellular growth inhibition caused by this trace element.

Animals↗
PubMed1992

Identification and characterization of a coronavirus packaging signal.

Previously, a mouse hepatitis virus (MHV) genomic sequence necessary for defective interfering (DI) RNA packaging into MHV particles (packaging signal) was mapped to within a region of 1,480 nucleotides in the MHV polymerase gene by comparison of two DI RNAs. One of these, DIssF, is 3.6 kb in size and exhibits efficient packaging, whereas the other, DIssE, which is 2.3 kb, does not. For more precise mapping, a series of mutant DIssF RNAs with deletions within this 1,480-nucleotide region were constructed. After transfection of in vitro-synthesized mutant DI RNA in MHV-infected cells, the virus product was passaged several times. The efficiency of DI RNA packaging into MHV virions was then estimated by viral homologous interference activity and by analysis of intracellular virus-specific RNAs and virion RNA. The results indicated that an area of 190 nucleotides was necessary for packaging. A computer-generated secondary structural analysis of the A59 and JHM strains of MHV demonstrated that within this 190-nucleotide region a stable stem-loop of 69 nucleotides was common between the two viruses. A DIssE-derived DI DNA which had these 69 nucleotides inserted into the DIssE sequence demonstrated efficient DI RNA packaging. Site-directed mutagenic analysis showed that of these 69 nucleotides, the minimum sequence of the packaging signal was 61 nucleotides and that destruction of the secondary structure abolished packaging ability. These studies demonstrated that an MHV packaging signal was present within the 61 nucleotides, which are located on MHV genomic RNA 1,381 to 1,441 nucleotides upstream of the 3' end of gene 1.

Animals↗
PubMed1990

Primary amino acid sequence of alpha-trichosanthin and molecular models for abrin A-chain and alpha-trichosanthin.

Ricin A-chain, abrin A-chain, and alpha-trichosanthin are members of a larger group of proteins called ribosome-inactivating proteins. These proteins all function to catalytically inactivate eukaryotic 60 S ribosomal subunits leading to rapid shutdown of protein synthesis. They are homologous in sequence and are probably evolutionarily related. We have determined the complete primary amino acid sequence of alpha-trichosanthin and have found it to be homologous, as expected, to that of abrin A-chain and ricin A-chain. A crystal structure for ricin, which includes ricin A-chain and ricin B-chain, has been determined from x-ray diffraction data. Based on the sequence homologies of these proteins, we fit the primary sequences of abrin A-chain and alpha-trichosanthin to the backbone structure for ricin A-chain and have generated energy-minimized molecular models for them. These models should prove useful in studying the structural-functional relationships of these proteins in particular and of the class in general.

Abrin↗
PubMed1987

Calcium regulation in vascular smooth muscle contractility.

The contractile activity of vascular smooth muscle is regulated by control over the cytoplasmic calcium concentration. The intracellular calcium receptor is calmodulin, which, through stimulation of myosin light chain kinase, can activate 2 different contractile states. The calcium is supplied from the sarcoplasmic reticulum and the extracellular space; a minor component is supplied from the inner surface of the plasmalemma. The main intracellular messenger responsible for the transduction of receptor occupation and calcium release from the sarcoplasmic reticulum is IP3 and, to a lesser extent, calcium itself. The superficial location of the sarcoplasmic reticulum in vascular smooth muscle makes it the logical area for control of calcium entry due to calcium leak or through either or both types of calcium channel. The sarcoplasmic reticulum, therefore, acts as a "superficial calcium buffer barrier" and is probably the major system controlling free cytoplasmic calcium concentration in vascular smooth muscle.

Animals↗
PubMed1981

Evidence that platelet buoyant density, but not size, correlates with platelet age in man.

Following infusion of 51Cr-labeled autologous platelets into normal subjects, high-density (HD) and low-density (LD) platelet cohorts were isolated by prolonged centrifugation in isosmotic arabino-galactan (Stractan). Specific radio-activity of LD platelets declined rapidly post-infusion (T1/2 = 1.5 days), but specific radioactivity of HD platelets remained constant or increased over a 3--4-day period and gradually declined for 6--7 days thereafter. These differences were exaggerated when platelet cohorts enriched in LD or HD cells by slow centrifugation in high-density albumin were labeled and transfused. Mean survival of a platelet cohort enriched with HD cells was significantly (P less than 0.02) shorter (7.73 days) than that of a cohort enriched with LD cells (9.33) days). In normal subjects treated with aspirin, capacity for thromboxane synthesis was regained more rapidly (P less than 0.05) in LD than in HD platelets. HD and LD platelets differed only slightly in mean volume (HD platelets = 7.57 mu3, LD platelets = 6.87 mu3, 0.05 less than P less than 0.01). We believe the most logical interpretation of these findings is that under normal conditions in man, newly formed platelets are less dense on the average than total platelets and become more dense as they age in the circulation. Thus, specific radioactivity of LD platelets declines rapidly as these platelets move into a more dense compartment and are replaced by newly formed, unlabelled cells; specific radioactivity of HD platelets remains constant or increases as labelled platelets enter this compartment in numbers equal to or greater than the number leaving it at the end of their life span. The similarity in mean volumes of LD and HD platelets suggests that platelet size is unrelated to platelet age under normal conditions.

Adult↗
PubMed1976

Drugs derived from cannabinoids. 5. delta6a,10a-Tetrahydrocannabinol and heterocyclic analogs containing aromatic side chains.

Ten new delta6a,10a-THC analogs with arylalkyl side chains, one with a dimethylaminoalkyl side chain, and six heterocyclic delta6a,10a-THC analogs [8-substituted 5,5-dimethyl-10-hydroxy-2-(2-propynyl)-1,2,3,4-tetrahydro-5H-[1]benzo-pyrano[4,3-c]pyridines] were prepared. They showed pharmacological activity as analgesics, tranquilizers, antihypertensives, and hypnotics and as antisecretory, antiulcer, and antidiarrheal agents. The most potent compounds had either a 1-methyl-4-(4-fluorophenyl)butyl or a 1,2-dimethyl-4-(4-fluorophenyl)butyl side chain.

Aggression↗
PubMedDate not supplied

Appendiceal CT in 140 cases. Diagnostic criteria for acute and necrotizing appendicitis.

Computed tomography (CT) was performed in 140 patients with suspected acute appendicitis. Thin collimation (5 mm), intravenous contrast enhancement, 1-second scan times, and supplementary cecal air insufflation were emphasized. CT accuracy was 98% overall (137/140), and 99% in the 124 cases with early surgery. Necrotizing appendicitis was diagnosed by CT with 86% accuracy and 90% positive predictive value.

Acute Disease↗
PubMedDate not supplied

Coronary blood flow and thallium 201 uptake in rejecting rat heart transplantations.

The effects of rejection on coronary flow (CAF) in heart allografts are unclear, although previous evidence with cardiac imaging agents indicates impaired flow during advanced rejection. The purpose of this study was to measure CAF in heterotopically placed heart grafts. Lewis rats (LEW) received grafts from either syngeneic Lewis rats (LEW/LEW group) or allogeneic ACI rats (ACI/LEW group). CAF was measured in both the transplanted and native hearts with radiolabeled microspheres. Rejection was measured histologically (grades 0 [absent] to 4+ [severe]). In addition systemic blood pressure and cardiac outputs of the native hearts were determined with microspheres. Different animals were studied during relatively early (4 days) and late (6 days) rejection. Among the 4-day animals a cyclosporine-treated group was included (ACI/LEW CyA). In 6-day rats CAF in allografts was lower (0.56 +/- .06 ml/gm/min) compared with syngeneic grafts (1.72 +/- 0.4 ml/gm/min) (p less than 0.05). The CAF in the native hearts did not differ significantly but was higher than in the grafts in both groups. Heart rates were reduced in allografts (p less than 0.05). It is interesting that arterial pressure and cardiac output were significantly lower in animals bearing allogeneic than syngeneic grafts. In rats studied at 4 days graft CAF was lower than in the native heart in both the LEW/LEW and ACI/LEW groups, but there was no significant difference in behavior between groups. The same was true for a cyclosporine-treated group. Graft heart rates were similar in all 4-day rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗