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Biomedical subjects

J W Hong

Publications and source records attributed to J W Hong.

At least 19 recordsLinked to original sources
PubMed2005

Direct determination of verapamil in rat plasma by coupled column microbore-HPLC method.

This report describes an automated coupled column microbore-high-performance liquid chromatography (HPLC) with fluorescence detection for direct determination of verapamil in small volume of rat plasma. We used HPLC system consisting of three columns such as precolumn, intermediate and analytical column and six-port switching valve and injected small volume of rat plasma to the system without sample preparation. An aliquot of sample was directly injected into Capcell Pak MF Ph precolumn for clean-up and enrichment, 35 mm Capcell Pak C18, intermediate column for concentration of compounds and 250 mm Capcell Pak C18 analytical column for separation of compounds and two mobile phases are used as mobile phase A (50mM ammonium phosphate, pH 4.5) and B (50mM ammonium phosphate:acetonitrile=70:30 v/v). Analysis of verapamil and internal standard, propranolol was performed with direct injection of 10 microl of rat plasma to the system and were eluted at 22 and 12 min, respectively, at a mobile phase flow rate of 0.5 (mobile phase A) and 0.15 ml/min (mobile phase B). The peaks of verapamil and internal standard were good shapes and well separated from any interfering endogenous peaks during a total run time of 25 min. The calibration curve for verapamil showed good linearity (r(2)=0.9997) over the concentration range of 0.01-2.50 microg/ml. The mean RSD (%) values of intra-day (n=5) and inter-day (n=5) variability of verapamil ranged from 1.96 to 9.06 and 0.62 to 3.08%, respectively. The LOD and LOQ were 0.01 and 0.025 microg/ml, respectively, for verapamil using 10 microl of rat plasma. An automated coupled column microbore-HPLC method was successfully applied to a pharmacokinetic study after intravenous injection of 3mg/kg of verapamil to the normal and dimethylnitrosamine (DMN)-induced hepatofibrotic rats.

Animals↗
PubMed2001

The wound healing response after laser in situ keratomileusis and photorefractive keratectomy: elusive control of biological variability and effect on custom laser vision correction.

Biological diversity in the wound healing response is thought to be a major factor limiting the predictability of the outcome of refractive surgical procedures such as laser in situ keratomileusis and photorefractive keratectomy. Corneal wound healing is critical to the success of topography-linked or wave front-linked excimer laser ablation to optimize visual performance. This is because of the importance of retaining subtle features of custom ablation and the tendency of epithelial hyperplasia and stromal remodeling to obscure these features following either procedure. The corneal wound healing response is exceedingly complex. Keratocyte apoptosis, which occurs in response to epithelial injury, is the earliest observable event in the wound healing cascades and is therefore an excellent target for pharmacological intervention. Alterations of surgical technique can be designed to limit keratocyte apoptosis and the subsequent events in corneal wound healing. Abnormalities of the cascades could contribute to the pathogenesis of corneal diseases. For example, recent data have suggested that perturbation of the keratocyte apoptosis/mitosis balance could underlie the development of keratoconus in a proportion of patients.

Animals↗
PubMed2001

Integration of gene amplification and capillary gel electrophoresis on a polydimethylsiloxane-glass hybrid microchip.

We report on the development of a hybrid polydimethylsiloxane (PDMS)-glass microchip for genetic analysis by functional integration of polymerase chain reaction (PCR) and capillary gel electrophoresis (CGE), and on related temperature control systems for PCR on a PDMS-glass hybrid microchip. The microchip was produced by molding PDMS against a microfabricated master with comparatively simple and inexpensive methods. PCR was successfully carried out on the PDMS-glass hybrid microchip with 500 bp target of lambdaDNA and the amplified gene was subsequently analyzed by CGE on the same PDMS-glass microchip. The chip could be considered as an inexpensive single-use apparatus compared to glass or silicon-made microchips for the same purpose.

Bacteriophage lambda↗
PubMed2001

Differential expression analysis by gene array of cell cycle modulators in human corneal epithelial cells stimulated with epidermal growth factor (EGF), hepatocyte growth factor (HGF), or keratinocyte growth factor (KGF).

PURPOSE: To identify and differentiate cell cycle and differentiation genes that are up-regulated or down-regulated in human corneal epithelial cells in response to alternative epithelium-modulating cytokines epidermal growth factor (EGF), hepatocyte growth factor (HGF) or keratinocyte growth factor (KGF). METHODS: Primary cultures human corneal epithelial cell (HCE) were treated with 25 ng/ml of EGF, 25 ng/ml HGF, 25 ng/ml KGF, or vehicle for 8 hours. Complementary DNA (cDNA) probes were synthesized from total cellular RNA isolated from the HCE cells. The cDNA probes were hybridized to the Atlas human cell cycle/differentiation array membrane. RNAse protection assay was used to confirm up-regulation of the serine/threonine-protein kinase PITALRE gene by EGF, KGF, and HGF. RESULTS: The expression of one hundred and eleven cell cycle and differentiation genes was monitored with the gene array system. It was found that these epithelial cell-modulating cytokines shared similar effects on some of the cell cycle and differentiation genes that were monitored, but had specific effects on some cytokines. Up-regulation of PITALRE gene expression was confirmed using RNAse protection assay. CONCLUSION: EGF, HGF and KGF had differential effects on cell cycle- and differentiation-related gene expression in corneal epithelial cells. For example, all three mitogenic growth factors up-regulated the expression of cyclin D1 (BCL-1 oncogene) and serine/threonine-protein kinase PITALRE in the primary cultured human corneal epithelial cells. However, EGF and KGF, but not HGF, up-regulated expression of the E2F-1 pRB-binding protein gene. Thus, while these three epithelial mitogens have similar effects on many genes that were analyzed, important differences were noted that may relate to differing effects of these growth factors on corneal epithelial cells. Studies to analyze the significance of the identified differences among these growth factors are in progress.

Cell Cycle↗
PubMed2001

Proinflammatory chemokine induction in keratocytes and inflammatory cell infiltration into the cornea.

PURPOSE: To determine the effect of interleukin (IL)-1alpha and tumor necrosis factor (TNF)-alpha on cytokine, chemokine, and receptor expression in corneal stromal cells; the effect of corneal scrape injury on monocyte chemotactic and activating factor (MCAF) expression and monocyte-macrophage influx into the stroma; and the effect of MCAF and granulocyte colony-stimulating factor (G-CSF) microinjection on inflammatory cell infiltration into the stroma. METHODS: Gene array technology was used to evaluate changes in cytokine, chemokine, and receptor gene expression in stromal fibroblasts in response to IL-1alpha and TNFalpha. Expression of MCAF mRNA and protein was monitored with an RNase protection assay and Western blot analysis, respectively. Keratocyte MCAF protein expression in the rabbit cornea was detected with immunocytochemistry. After epithelial scrape injury, monocytes-macrophages were detected in rabbit corneas, by immunocytochemistry for monocyte-macrophage antigen. Inflammatory cell infiltration after MCAF and G-CSF microinjection into the stroma of mouse corneas was monitored with hematoxylin and eosin staining. RESULTS: IL-1alpha or TNFalpha upregulated the expression of several proinflammatory chemokines in stromal fibroblasts in culture. These included G-CSF, MCAF, neutrophil-activating peptide (ENA-78), and monocyte-derived neutrophil chemotactic factor (MDNCF). MCAF mRNA upregulation was confirmed by RNase protection assay, and MCAF protein was detected by Western blot analysis. MCAF protein was detected in keratocytes at 4 hours and 24 hours after epithelial injury, but not in keratocytes in the unwounded cornea. Corneal epithelial injury triggered the influx of monocytes-macrophages into the corneal stroma in the rabbit. Microinjection of MCAF and G-CSF into mouse cornea resulted in the influx of monocytes-macrophages and granulocytes, respectively, into the stroma. CONCLUSIONS: Proinflammatory chemokine induction in keratocytes is mediated by IL-1alpha and TNFalpha. The proinflammatory chemokines produced by the keratocytes probably trigger the influx of inflammatory cells into the stroma after epithelial injury associated with corneal surgery, contact lenses, or trauma.

Blotting, Western↗
PubMed2000

Bowman's layer structure and function: critical or dispensable to corneal function? A hypothesis.

PURPOSE: The purpose of this article is to review available information regarding development, structure, and function of Bowman's layer in the cornea. Disease-related abnormalities of Bowman's layer are described. A hypothesis is advanced to explain the development and maintenance of Bowman's layer. METHODS: Literature review and hypothesis formulation based on previous studies. RESULTS: Information is presented that supports the hypothesis that Bowman's layer forms as a result of cytokine-mediated interactions occurring between corneal epithelial cells and keratocytes that include chemotactic and apoptotic effects on the keratocytes. This hypothesis suggests that Bowman's layer results from such interactions beginning in early development and continuing into adulthood in humans and other animals, such as chickens. CONCLUSIONS: Bowman's layer may be a visible indicator of ongoing stromal-epithelial interactions in the human and have no critical function in corneal physiology. Bowman's layer is commonly destroyed in diseases such as advanced bullous keratopathy where stromal-epithelial interactions may be interrupted. Bowman's-like layers often form in response to epithelium, for example when epithelial plugs extend into the stroma in corneas with radial keratotomy incisions.

Animals↗
PubMed1999

Different antigenic reactivities of bovine brain glutamate dehydrogenase isoproteins.

The structural differences between two types of glutamate dehydrogenase (GDH) isoproteins (GDH I and GDH II), homogeneously isolated from bovine brain, were investigated using a biosensor technology and monoclonal antibodies. A total of seven monoclonal antibodies raised against GDH II were produced, and the antibodies recognized a single protein band that comigrates with purified GDH II on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblot. Of seven anti-GDH II monoclonal antibodies tested in the immunoblot analysis, all seven antibodies interacted with GDH II, whereas only four antibodies recognized the protein band of the other GDH isoprotein, GDH I. When inhibition tests of the GDH isoproteins were performed with the seven anti-GDH II monoclonal antibodies, three antibodies inhibited GDH II activity, whereas only one antibody inhibited GDH I activity. The binding affinity of anti-GDH II monoclonal antibodies for GDH II (K(D) = 1.0 nM) determined using a biosensor technology (Pharmacia BIAcore) was fivefold higher than for GDH I (K(D) = 5.3 nM). These results, together with epitope mapping analysis, suggest that there may be structural differences between the two GDH isoproteins, in addition to their different biochemical properties. Using the anti-GDH II antibodies as probes, we also investigated the cross-reactivities of brain GDHs from some mammalian and an avian species, showing that the mammalian brain GDH enzymes are related immunologically to each other.

Animals↗
PubMed1999

The relationship between rabbit corneal opacity and immunohistochemical expression of heat shock protein 72/73 and c-fos after excimer laser photorefractive keratectomy.

To evaluate the etiology of corneal opacities, a study was done on the immunohistochemical staining for heat shock protein (HSP) 72/73 and c-fos after myopic excimer laser photorefractive keratectomy (PRK). New Zealand white rabbits (60 eyes) were divided into four groups: -6-, -9- and -15-dpt operation groups and a control group (only corneal epithelium removed). Using an excimer laser (VisX 20/20, Sunnyvale, Calif., USA), myopic PRK was performed on the rabbit's cornea by a single or multizone technique followed by an immunohistochemical stain to detect the expression of HSP 72/73 and c-fos at 6, 24, 48 h, 1 week and 8 weeks. Corneal epithelia were healed within 3 days in all groups, and 8 weeks after the operation, the mean density of corneal opacity was 0.83 (-6-dpt operation group), 1 (-9-dpt operation group) and 1.67 (-15-dpt operation group). All groups exhibited HSP 73 in corneal epithelium and stroma. However, the maximal expression of c-fos and HSP 72 appeared in corneal epithelium at 24 and 48 h, respectively, after the operation in the -15-dpt group. These results suggest that the expressions of HSP 72 and c-fos in rabbit corneal epithelium are significant factors in relation to corneal opacity after excimer laser PRK.

Animals↗
PubMed1997

Modulation of the catalytic activity of brain succinic semialdehyde reductase by reaction with pyridoxal 5'-phosphate.

An NADPH-dependent succinic semialdehyde reductase from bovine brain was inactivated by pyridoxal 5'-phosphate. Spectral evidence is presented to indicate that the inactivation proceeds through formation of a Schiff's base with amino groups of the enzyme. After sodium borohydride reduction of the inactivated enzyme, it was observed that 1 mol phosphopyridoxyl residue was incorporated/mol enzyme monomer. The coenzyme, NADPH, protected the enzyme against inactivation by pyridoxal 5'-phosphate. After tryptic digestion of the enzyme modified with pyridoxal 5'-phosphate in the presence and absence of NADPH followed by [1H]NaBH4 reduction, a radioactive peptide absorbing at 310 nm was isolated by reverse-phase HPLC. The amino acid sequence of the peptide identified a portion of the pyridoxal-5'-phosphate-binding site as the region containing the sequence I-L-E-N-I-Q-V-F-X-K, where X indicates that the phenylthiohydantoin amino acid could not be assigned. The missing residue, however, can be designated as a phosphopyridoxyl lysine as interpreted from the result of amino acid composition of the peptide. It is suggested that the catalytic function of succinic semialdehyde reductase is modulated by binding of pyridoxal 5'-phosphate to a specific lysyl residue at or near the coenzyme-binding site of the protein.

Amino Acids↗
PubMed1997

Distribution of succinic semialdehyde reductase in rat brain.

Succinic semialdehyde reductase (SSR) that catalyzes the reduction of succinic semialdehyde (SSA) to gamma-hydroxybutyrate (GHB) has been identified as one of the NADPH-dependent aldehyde reductases. Reduction of SSA to GHB strongly supports the proposal that GHB biosynthesis may be an important step in the GABA shunt. It is pharmacologically significant in anesthesia, evoking the state of sleep, and an increase in brain dopamine level. Monoclonal antibodies against bovine brain succinic semialdehyde reductase were produced. Using the anti-succinic semialdehyde reductase antibodies, we investigated the distribution of brain succinic semialdehyde reductase in rat brain. The brain tissues were sectioned with a basis on the rat brain atlas of Paxinos and were stained by the immunoperoxidase staining method using monoclonal antibodies. In the section of the frontal lobe, immunoreactive cells were observed in the lateral septal area, the ventral pallidum, which belongs to the substantia innominata. We could observe immunoreactive cells in the reticular thalamic nucleus, which is closely related with 'sleeping', the basal nuclei of Meynert, which is associated with Alzheimer's disease, and hypothalamic nuclei. Immunoreactive cells were also shown in raphe nuclei or the reticular formation of the midbrain, cerebellum, and inferior olivary nuclei of the medulla oblongata. Succinic semialdehyde reductase-immunoreactive cells were distributed extensively in rat brain, especially immunoreactive cells were strongly observed in the areas associated with the limbic system and reticular formation.

Animals↗
PubMed1997

The changes of tear break up time after myopic excimer laser photorefractive keratectomy.

We compared the tear break-up time (BUT) and Schirmer test value after myopic excimer laser photorefractive keratectomy (PRK). Patients with normal preoperative Schirmer test value and BUT were included. Pre- and post-operative tear break-up time and Schirmer test values were measured in 220 eyes who underwent PRK. Minimum follow-up was 6 months. Visx 20/20 B excimer laser was used for myopic PRK. Six months after surgery, no significant changes in Schirmer test value between pre- and post-operation were observed. However, 47.8% of eyes showed a decrease in BUT after surgery, and 72.7% of patients with decreased BUT complained of dry eye symptom. There was no significant relationship between BUT changes and uncorrected visual acuity after PRK. BUT changes did not influence the PRK visual outcome, but excimer laser PRK may change the tear break-up time and cause a dry eye symptom.

Adult↗
PubMed1996

Inactivation of an NADPH-dependent succinic semialdehyde reductase by o-phthalaldehyde.

Incubation of an NADPH-dependent succinic semi-aldehyde reductase from bovine brain with o-phthalaldehyde resulted in a time-dependent loss of enzyme activity. The inactivation followed pseudo first-order kinetics with the second-order rate constant of 28 M(-1) s(-1). The inactivation was prevented by preincubation of the enzymes with NADPH, but not by succinic semialdehyde. There was a linear relationship between isoindole formation and the loss of enzyme activity. Spectrophotometric studies indicated that complete inactivation of the enzyme resulted from the formation of one isoindole derivative per molecule of enzyme, which was formed from the reaction of cysteine and lysine residues with o-phthalaldehyde at or near the enzyme active site.

Animals↗
PubMed1996

Occult lumbar lateral spinal stenosis in neural foramina subjected to physiologic loading.

PURPOSE: To measure the effect of extension, flexion, lateral bending, and axial rotation loads applied to the spine on the anatomic relationship of the spinal nerves in the neural foramen to the ligamentum flavum and the intervertebral disk, anc to determine the effect of disk degeneration on the response to loading. METHODS: Cadaveric lumbar motion segments were examined with CT and MR imaging, loaded with pure moment forces, frozen in situ, reexamined with CT, and sectioned with a cryomicrotome. The morphology of the intervertebral disks was classified on the basis of the appearance of the cryomicrotome sections. The neural foramina were classified as having no evident stenosis, as being stenotic, as having occult stenosis, or as showing resolved stenosis on the basis of the images and sections before and after loading. The stenotic and nonstenotic foramina were stratified by disk level, intervertebral disk classification, and type of loading applied. The effect of spinal level, disk type, and load type on the prevalence of stenosis was studied. RESULTS: On average, extension, flexion, lateral bending, and axial rotation resulted in the ligamentum flavum or intervertebral disk contacting or compressing the spinal nerve in 18% of the neural foramina. Extension loading produced the most cases of nerve root contact, and lateral bending produced the fewest cases. Each of the loading types resulted also in diminished contact between the spinal nerve and the intervertebral disk or ligamentum flavum in some cases. Disk degeneration significantly increased the prevalence of spinal stenosis. All foramina associated with advanced disk degeneration and half of the foramina associated with disks having radial tears of the annulus fibrosus either developed occult stenosis or were stenotic before loading. CONCLUSIONS: The study supports the concept of dynamic spinal stenosis; that is, intermittent stenosis of the neural foramina. Flexion, extension, lateral bending, and axial rotation significantly changed the anatomic relationships of the ligamentum flavum and intervertebral disk to the spinal nerve roots.

Adult↗
PubMed1995

[Retroperitoneoscopic nephrectomy without pneumoperitoneum--experiments in pigs].

Laparoscopic nephrectomy has been performed widely for minimally invasive therapy. However, the procedure of insertion of needles and trocars can cause vascular and intestinal injuries. In addition, pneumoperitoneum using high pressure CO2 gas can cause circulatory and respiratory problems. In order to avoid these problems, we tried retroperitoneoscopic nephrectomy without CO2 gas in 8 kidneys of 4 pigs. A 1.5 cm skin incision was made just below the lowest rib and a small retroperitoneal space was made with the forefinger. The sheath of a 27 Fr rigid nephroscope was covered with a condom balloon and inserted into the retroperitoneal space. Under observing through the nephroscope, the condom was filled with 150-200 ml saline to make a space for the operation. After removing the nephroscope with condom, a scope and trocars were inserted into the space and retroperitoneoscopic nephrectomy was performed. Making the space with condom balloon in the retroperitoneal space was very efficient. The procedures succeeded in 8 and average procedure time was 3 hours. Retroperitoneoscopic nephrectomy without gas is a very attractive minimally invasive technique.

Animals↗
PubMed1991

[Preliminary study of naturally occurring anti-idiotypic antibodies in schistosomiasis japonica].

In this study, naturally occurring anti-idiotypic antibodies in sera from patients with schistosomiasis japonica were demonstrated by using McAb (5B5H)-ELISA. McAb 5B5H against Schistosoma japonicum soluble egg antigen (SEA) was purified by precipitation with 50%, 40% and 33% saturated (NH4)2SO4 and coupled to CNBr-activated Sepharose 4B (Pharmacia). 5B5H column was loaded with sera from two patients with schistosomiasis japonica and then the bound material was eluated with 3M KCNS. The resulting eluate was further characterized with McAb-ELISA and complement fixation test in order to minimize the possible interference of circulating antigen-antibody complex. The results showed that the eluate contained mainly anti-Id antibodies. In the competitive 5B5H-ELISA tests, SEA markedly inhibited the interaction of 5B5H (Id) and anti-Id anti-bodies, suggesting that the relevant idiotype is within or adjacent closely to antigen binding site of anti-SEA molecule. The anti-Id antibodies were detected using 5B5H-ELISA in patients with schistosomiasis japonica from A and B areas, positive rate of 35.1% (13/37) and 60% (18/30) was obtained respectively. No cross or false reactions were found with sera from patients with fasciolopsiasis buski (0/15), clonorchiasis sinensis (0/15) and normal group of students (0/54) with the exception of one out of 20 patients with paragonimiasis westermani.

Animals↗