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Biomedical subjects

D Hong

Publications and source records attributed to D Hong.

48 records · Page 3Linked to original sources
PubMed1992

Schwann cells and cells in the oligodendrocyte lineage proliferate in response to a 50,000 dalton membrane-associated mitogen present in developing brain.

The neuronal cell surface is believed to carry a mitogenic signal for peripheral glial cells. We have purified a mitogen from fetal bovine brain membranes that, in common with the PNS neuronal mitogen, stimulates the proliferation of Schwann cells in vitro and binds heparin. The purified mitogen has an apparent molecular weight of 50,000 daltons as estimated by elution of activity from non-reducing polyacrylamide gels. Since the developing central nervous system is a rich source of mitogen, we tested whether the protein is mitogenic for one or more cell types isolated from the developing brain. Purified mitogen was added to enriched cultures of astrocytes or developing oligodendrocytes, or to microglial cells. The analyses demonstrated that the protein is mitogenic for developing oligodendrocytes but not astrocytes or microglial cells. These results suggest that during development a membrane-associated mitogen present in the brain might regulate the proliferation of developing oligodendrocytes, and consequently, the population size of oligodendrocytes in the brain.

Animals↗
PubMed1991

Effects of asymmetric load carrying on the biomechanics of walking.

The purpose of the study was to investigate the effects of an asymmetric sidepack carrying system on frontal plane joint moments of force in both lower extremities and in the L5/S1 joint during level walking. Ground reaction force data and frontal plane film records were obtained from five males performing three walking conditions: 0, 10 and 20% bodyweight loads in a sidepack supported by the left shoulder. Inverse dynamics were used to calculate the lower extremity moments during stance and a static model of the pelvis was used to calculate the L5/S1 moments during single support for each limb. Normal walking was characterized by symmetric kinetics between left and right limbs and around the L5/S1 joint. The asymmetric loads produced unbalanced lateral trunk muscle dominance between left and right limb stance phases, increased right hip and knee moments and decreased left hip and knee moments. During normal walking, the L5/S1 moment was dominant on the contralateral trunk side for both limbs. The asymmetric loads applied to the left side caused a shift in L5/S1 moment dominance to the right side during left and right single support phases.

Adult↗
PubMed1990

New potent topical anti-inflammatory steroids with reduced side effects: derivatives of steroid-16-carboxy esters.

Therapeutic use of anti-inflammatory steroids is limited due to their potential suppressive effects on pituitary-adrenal function and the immune system. Based on the antedrug concept, a new class of potent locally active compounds with reduced risk of side effects has been synthesized from prednisolone by introducing a metabolically labile methoxycarbonyl substituent at C-16. Results of topical application of the lead compound, methyl 11 beta,17 alpha,21-trihydroxy-3,20-dioxo-pregna-1,4-diene-16 alpha-carboxylate (P16CM;1), showed that it was 14 times more potent than prednisolone and that it had a greatly reduced tendency to cause systemic side effects. In the present investigations, we have demonstrated that chemical modifications such as 17- and/or 21-esterifications and 17,21-acetonidation of 1 further enhance topical activity in the croton oil ear edema model in rats. Following multiple topical ID50 applications of 1 or its derivatives, no thymolysis was noted. In the carrageenan-soaked sponge model of acute inflammation, all derivatives were potent inhibitors of leukocyte migration, generation of PGE2, and release of elastase. Taken together, these results indicate that esterification or acetonidation of hydroxyl groups at the 17 and/or 21 position, in combination with a labile C-16 methoxycarbonyl group, increases topical activity without concomitantly increasing the risk of side effects.

Adrenal Glands↗
PubMed1987

Button batteries as foreign bodies in the nasal cavities.

Two cases of foreign bodies (button batteries) in the nasal cavities were reported. The first patient was a 6-year-old girl who put a button battery into her left nostril and ulceration of the septum and inferior turbinate was found. The other patient was a 3-year-old boy, the alkaline battery caused neither septal perforation nor stenosis of the nasal meatus. All button batteries as foreign bodies in the nasal cavities should be removed immediately to prevent severe local tissue damage, resulting in late sequels, such as septal perforation or stenosis of the nasal meatus.

Child↗
PubMed1984

The role of protein synthesis in the chemotaxis and chemiluminescence of human polymorphonuclear leukocytes.

We investigated the role of protein synthesis in human polymorphonuclear leukocyte (PMN) chemotaxis and luminol-dependent chemiluminescence (CL). We used cycloheximide and puromycin to inhibit protein synthesis, and determined the extent of synthesis by measurement of 14C-amino acid incorporation. With 2-hour incubations both puromycin at 9.0 X 10(-6) M and cycloheximide at 1.8 X 10(-6) M inhibited PMN protein synthesis. At concentrations of 2-4 X 10(-5) M both cycloheximide and puromycin inhibited PMN-chemotaxis 40 and 55%, respectively. However, inhibition was observed only when using zymosan-activated serum and not formyl-methionyl-phenylalanine as a chemoattractant. Using 2-hour incubations, PMN-CL was also suppressed by puromycin and cycloheximide, at 20 and 40%, respectively. The data demonstrated that protein synthesis had an important role in chemotaxis that was dependent on the chemoattractant and perhaps the cellular receptor involved in that process. CL did not require de novo protein synthesis but appeared to depend on protein(s) with a relatively rapid turnover.

Carbon Radioisotopes↗
PubMedDate not supplied

New approach to radial expansive force measurement of self expandable esophageal metal stents.

The accurate measurement of radial expansive force is crucial for optimal design and implantation of self expandable esophageal metal stents. In the present study, a new method of measurement under experimental conditions simulating actual stent implantation has been developed. This method offers precise and reproducible measurements and can be applied to a wide variety of stent types. In particular, the method enables one to measure expansive pressure as well as the true radial expansive force up to the radial compression ratio of 72%, covering the range of compression often encountered in a partially obstructed lumen. The test results for various kinds of metal stents are presented and compared. Based on these results, three important points of observation critical in explaining and predicting the expansion characteristics of stents have been reported. Further understanding and characterization of these findings will be necessary for developing new stents with outstanding clinical efficacy.

Compliance↗