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Biomedical subjects

Jae Young Choi

Publications and source records attributed to Jae Young Choi.

At least 19 recordsLinked to original sources
PubMed2007

Interleukin-1beta upregulates Na+-K+-2Cl- cotransporter in human middle ear epithelia.

Disruption of periciliary fluid homeostasis is the main pathogenesis of otitis media with effusion (OME), one of the most common childhood diseases. Although the underlying molecular mechanisms are unclear, it has been suggested that the altered functions of ion channels and transporters are involved in the fluid collection of middle ear cavity of OME patients. In the present study, we analyzed the effects of a major cytokine interleukin (IL)-1beta, which was known to be involved in the pathogenesis of OME, on Na(+)-K(+)-2Cl(-) cotransporter (NKCC) in human middle ear cells. Intracellular pH (pH(i)) was measured in primary cultures of normal human middle ear epithelial (NHMEE) cells using a double perfusion chamber, which enabled us to analyze the membrane-specific transporter activities. NKCC activities were estimated by the pH(i) reduction due to bumetanide-sensitive intracellular uptake of NH(4) (+). In NHMEE cells, NKCC activities were observed only in the basolateral membrane, and immunoblotting using specific antibodies revealed the expression of NKCC1. Interestingly, IL-1beta treatments augmented the basolateral NKCC activities and increased NKCC1 expression. In addition, IL-1beta treatments stimulated bumetanide-sensitive fluid transport across the NHMEE cell monolayers. Furthermore, an elevated NKCC1 expression was observed in middle ear cells from OME patients when compared to those from control individuals. The above results provide in vitro and in vivo evidence that the inflammatory cytokine IL-1beta upregulates NKCC1 in middle ear epithelial cells, which would be one of the important underlying mechanisms of excess fluid collection in OME patients.

Ammonium Chloride↗
PubMed2007

Mucus secretion by single tracheal submucosal glands from normal and cystic fibrosis transmembrane conductance regulator knockout mice.

Submucosal glands line the cartilaginous airways and produce most of the antimicrobial mucus that keeps the airways sterile. The glands are defective in cystic fibrosis (CF), but how this impacts airway health remains uncertain. Although most CF mouse strains exhibit mild airway defects, those with the C57Bl/6 genetic background have increased airway pathology and susceptibility to Pseudomonas. Thus, they offer the possibility of studying whether, and if so how, abnormal submucosal gland function contributes to CF airway disease. We used optical methods to study fluid secretion by individual glands in tracheas from normal, wild-type (WT) mice and from cystic fibrosis transmembrane conductance regulator (CFTR) knockout mice (Cftr(m1UNC)/Cftr(m1UNC); CF mice). Glands from WT mice qualitatively resembled those in humans by responding to carbachol and vasoactive intestinal peptide (VIP), although the relative rates of VIP- and forskolin-stimulated secretion were much lower in mice than in large mammals. The pharmacology of mouse gland secretion was also similar to that in humans; adding bumetanide or replacement of HCO(3)(-) by Hepes reduced the carbachol response by approximately 50%, and this inhibition increased to 80% when both manoeuvres were performed simultaneously. It is important to note that glands from CFTR knockout mice responded to carbachol but did not secrete when exposed to VIP or forskolin, as has been shown previously for glands from CF patients. Tracheal glands from WT and CF mice both had robust secretory responses to electrical field stimulation that were blocked by tetrodotoxin. It is interesting that local irritation of the mucosa using chili pepper oil elicited secretion from WT glands but did not stimulate glands from CF mice. These results clarify the mechanisms of murine submucosal gland secretion and reveal a novel defect in local regulation of glands lacking CFTR which may also compromise airway defence in CF patients.

Animals↗
PubMed2006

Mutations of acetylcholinesterase1 contribute to prothiofos-resistance in Plutella xylostella (L.).

Insensitive acetylcholinesterase (AChE) is involved in the resistance of organophosphorous and carbamate insecticides. We cloned a novel full-length AChE cDNA encoding ace1 gene from adult heads of the diamondback moth (DBM, Plutella xylostella). The ace1 gene encoding 679 amino acids has conserved motifs including catalytic triad, choline-binding site and acyl pocket. Northern blot analysis revealed that the ace1 gene was expressed much higher than the ace2 in all examined body parts. The biochemical properties of expressed AChEs showed substrate specificity for acetylthiocholine iodide and inhibitor specificity for BW284C51 and eserine. Three mutations of AChE1 (D229G, A298S, and G324A) were identified in the prothiofos-resistant strain, two of which (A298S and G324A) were expected to be involved in the prothiofos-resistance through three-dimensional modeling. In vitro functional expression of AChEs in Sf9 cells revealed that only resistant AChE1 is less inhibited with paraoxon, suggesting that resistant AChE1 is responsible for prothiofos-resistance.

Acetylcholinesterase↗
PubMed2006

Intradural lumbar disc herniation--is it predictable preoperatively? A report of two cases.

BACKGROUND CONTEXT: Intradural disc herniations are thought to be rare events, and there have been relatively few literature reports of intradural disc herniations available with regard to magnetic resonance imaging findings. PURPOSE: The authors describe two patients with intradural lumbar disc herniations, one with and one without preoperative diagnosis, who had different postoperative outcomes. STUDY DESIGN: Case study METHODS: The first patient underwent an extended L3 subtotal laminectomy followed by bilateral medial facetectomy and foraminotomy at L3-L4. A durotomy uncovered large disc fragments comprised of friable disc materials and end plates, after no clear disc herniation was found in the epidural space. The second patient underwent anterior lumbar interbody fusion after a preoperative diagnosis of intradural disc herniation. RESULTS: The first patient experienced a marked reduction of pain and progressive recovery of sensory disturbance, but neurologic examination showed right foot drop postoperatively. Two years after surgery, she can not walk without a cane because the neurologic deficit of the right ankle has shown no improvement. Two days after surgery, the second patient was allowed to ambulate with a lumbar orthosis. Neurologic examination showed no motor deficit. Twenty-one months after surgery, the patient reports minimal back pain when sitting on a chair for prolonged periods of time. CONCLUSION: Our cases highlight the importance of preoperative diagnosis in the treatment of intradural lumbar disc herniations. The potential presence of an intradural disc herniation must always be considered preoperatively on a patient whose magnetic resonance imaging study demonstrates the "hawk-beak sign" on axial imaging as well as abrupt loss of continuity of the posterior longitudinal ligament (PLL). This association results in an adequate surgical approach, thereby reducing the chance of postoperative neurologic deficit. Finally, anterior lumbar interbody fusion can be a reasonable alternative in the treatment of intradural lumbar disc herniations.

Adult↗
PubMed2006

Risk factors of developing new symptomatic vertebral compression fractures after percutaneous vertebroplasty in osteoporotic patients.

Percutaneous vertebroplasty (PVP) is an efficient procedure to treat pain due to osteoporotic vertebral compression fractures (OVCFs). However, some patient populations experience recurrent vertebral fracture after initial successful procedure. There are a lot of literatures about the effectiveness of this procedure but few concerning the development of recurrent, new compression fracture. This is a retrospective review of all PVPs performed in author's institution from September 1999 to December 2001 to investigate the factors related to the development of new symptomatic OVCFs after PVPs. A retrospective review of 244 cases of PVP for symptomatic OVCFs at 382 levels was performed. Sociodemographic, clinical, radiologic, and procedural data were analyzed and compared between the two patient groups (control group : no further symptomatic OVCFs after the initial PVP, "new symptomatic fracture" group: with newly developed symptomatic OVCF). Statistical analysis was performed between the variables of the two groups. Survival analysis was performed using the Kaplan-Meier method. Over all, 38 among 244 treated patients (15.6%) had experienced newly developed symptomatic OVCF(s) during the follow up period (mean 52.5 months). Old age and the presence of multiple treated vertebrae at the initial PVP were assessed as a strong parameter for predicting new symptomatic OVCF. With increasing preoperative wedging deformity the risk of developing new symptomatic OVCF decreased. The Kaplan-Meier estimate of the 1 year fracture-free rate was 92.2%. The Kaplan-Meier curve showed that 7.8% of the patients would experience new symptomatic OVCF within 1 year after initial PVP. A preoperative only mild wedge deformity of the fractured vertebra(e) could indicate the increased risk of developing new symptomatic OVCF after vertebroplasty.

Aged↗
PubMed2006

Dexamethasone increases fluid absorption via Na+/H+ exchanger (NHE) 3 activation in normal human middle ear epithelial cells.

The proper homeostasis of the liquid lining the surface of the middle ear cavity is vitally important for maintaining a fluid-free middle ear cavity. Disruption of this homeostasis leads to fluid collection in the middle ear cavity and results in otitis media with effusion. We demonstrated the molecular and functional expression of the Na+/H+ exchanger (NHE)s in normal human middle ear epithelial (NHMEE) cells. We also evaluated the role of NHEs in fluid absorption and the effect of dexamethasone on NHE function and NHE-dependent fluid absorption in NHMEE cells. Western blot analysis was performed for NHE1, -2, and -3 in NHMEE cells. The fluid absorption rate was measured after liquid application on the luminal surface of the cells. Intracellular pH (pHi) was measured using the pH-sensitive fluorescent probe bis-(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF)-AM. NHE activity was determined as Na+-induced pHi recovery from an acid load achieved by luminal exposure to 40 mmol/l NH4Cl. NHE1, -2 and -3 were all expressed in the NHMEE cells. The pHi recovery rate was suppressed by inhibition of NHE2 and -3 with HOE694 at concentrations greater than 50 microM. Inhibition of NHE3 with 650 microM of HOE694 or S3226 significantly decreased the fluid absorption rate. Dexamethasone increased the Na+-induced pHi recovery rate which was reversed by the inhibition of NHE3 with 650 microM of HOE694. Dexamethasone treatment up-regulated NHE3 expression in a dose-dependent manner. The fluid absorption rate was increased by treatment with dexamethasone (10(-7) M) and reversed by the inhibition of NHE3. In summary, we have shown that NHE3 are involved in the regulation of both pHi and fluid absorption on the luminal surface of NHMEE cells. Dexamethasone stimulates NHE3 expression and NHE3-dependent fluid absorption in NHMEE cells. These findings provide a new insight into mechanisms that regulate periciliary fluid and the therapeutic mechanisms behind steroid treatment of otitis media with effusion.

Absorption↗
PubMed2006

Characterization of the Helicoverpa assulta nucleopolyhedrovirus genome and sequence analysis of the polyhedrin gene region.

A local strain of Helicoverpa assulta nucleopolyhedrovirus (HasNPV) was isolated from infected H.assulta larvae in Korea. Restriction endonuclease fragment analysis, using 4 restriction enzymes, estimated that the total genome size of HasNPV is about 138 kb. A degenerate polymerase chain reaction (PCR) primer set for the polyhedrin gene successfully amplified the partial polyhedrin gene of HasNPV. The sequencing results showed that the about 430 bp PCR product was a fragment of the corresponding polyhedrin gene. Using HasNPV partial predicted polyhedrin to probe the Southern blots, we identified the location of the polyhedrin gene within the 6 kb Eco RI, 15 kb Nco I, 20 kb Xho I, 17 kb Bgl II and 3 kb Cla I fragments, respectively. The 3 kb Cla I fragment was cloned and the nucleotide sequences of the polyhedrin coding region and its flaking regions were determined. Nucleotide sequence analysis indicated the presence of an open reading frame of 735 nucleotides which could encode 245 amino acids with a predicted molecular mass of 29 kDa. The nucleotide sequences within the coding region of HasNPV polyhedrin shared 73.7% identity with the polyhedrin gene from Autographa californica NPV but were most closely related to Helicoverpa and Heliothis species NPVs with over 99% sequence identity.

Amino Acid Sequence↗
PubMed2006

Response to galvanic vestibular stimulation in patients with unilateral vestibular loss.

OBJECTIVES: This study sought to characterize various responses to galvanic vestibular stimulation (GVS) by comparing GVS-induced eye movements in healthy subjects and patients with vestibular function loss. The study also aimed to estimate the clinical significance of GVS tests. Finally, an effort was made to localize the primary excitation site of stimulation in the vestibular system. MATERIALS AND METHODS: Three parameters of response to GVS, spontaneous nystagmus, galvanic stimulating nystagmus (GSN), and postgalvanic stimulating nystagmus (PGSN), were evaluated in 20 normal subjects and 14 patients with complete unilateral vestibular function loss resulting from labyrinthectomy or vestibular neurectomy using a three-dimensional video-electronystagmography technique. RESULTS: In normal subjects, GSN was detected in all subjects and was directed toward the negative electrode. PGSN was also detected but was directed toward the opposite electrode. When the negative electrode was attached to the intact side in unilateral vestibular loss subjects, GSN was always directed toward the negative electrode and PGSN was never observed. When the negative electrode was attached to the lesion side, however, GSN was detected in only one case, and PGSN was observed and directed to the intact side in 13 patients. CONCLUSIONS: The response to GVS in vestibular loss patients differed from that in normal subjects, which suggests that GVS could be useful for estimating the extent of vestibular function loss. The fact that the patterns of GVS response differed so significantly suggests that the primary site of excitation is not central but is instead the peripheral vestibular organ.

Adolescent↗
PubMed2005

ENaC- and CFTR-dependent ion and fluid transport in human middle ear epithelial cells.

Ion channels, such as the epithelial sodium channel (ENaC), are essential for maintaining a fluid-free middle ear cavity by controlling periciliary fluid. Deviations from the normal volume or compositions of periciliary fluid are probably responsible for otitis media with effusion. To elucidate the physiologic roles of the ENaC and cystic fibrosis transmembrane conductance regulator (CFTR) in the middle ear mucosa, we compared the electrophysiological activity and protein expressions of ENaC and CFTR in normal human middle ear epithelial (NHMEE) cells with those in normal human nasal epithelial (NHNE) cells. We also evaluated the role of ENaC and CFTR in fluid transport by NHMEE cells. Short-circuit current (Isc) was measured in cell monolayers by modified Ussing chambers. Immunoblotting was performed for ENaC and CFTR. In addition, transepithelial fluid transport was measured after loading 100 microl of fluid onto the luminal cell surface. The amiloride-sensitive Isc in NHMEE cells was much larger than in NHNE cells, whereas the forskolin-induced Isc, presumably mediated by CFTR, was significantly smaller in NHMEE cells. ENaC subunits alpha, beta, and gamma were all detected in NHMEE cells, and their expressions were stronger than those in NHNE cells. In comparison, CFTR was also detected in the middle ear mucosa, but at a lower expression level than in NHNE cells. NHMEE cells showed more amiloride-sensitive fluid absorption than NHNE cells. In contrast, fluid absorption was less sensitive to forskolin/IBMX in NHMEE cells than in NHNE cells. The ATP induced Cl- efflux and the amplitude of ATP-induced current in NHMEE cells was much larger than in NHNE cells. In the present study, we have demonstrated an enhanced amiloride-sensitive Isc and fluid absorption in NHMEE cells, where the role of CFTR is limited. Our data also suggest that the ATP-induced Cl- channel could be an alternative Cl- channel to CFTR in NHMEE cells.

1-Methyl-3-isobutylxanthine↗
PubMed2005

P2Y2 agonist induces mucin secretion via Ca2+- and inositol 1,4,5-triphosphate-dependent pathway in human middle ear epithelial cells.

Purinergic agonists regulate mucin secretion in the airway epithelial cells. This study examined the effects of the apical application of purinergic agonists on Ca(2+) influx ([Ca(2+)](i)), and mucin secretion along with their underlying signaling pathway in normal human middle ear epithelial (NHMEE) cells. The apical membrane of NHMEE cells were stimulated with various purinergic agonists, including UTP, and the [Ca(2+)](i) was measured using a miniature Ussing double perfusion chamber. P2Y(2) receptor in NHMEE cells was also localized by immunohistochemistry. UTP-induced mucin secretion was quantified by an immunoblotting assay. The order of the purinergic agonist potency with respect to [Ca(2+)](i) determined in this study was ATP = UTP > 2-MeSATP > UDP >> adenosine which is consistent with that obtained from P2Y(2) receptor activation. The P2Y(2) receptor is expressed in the apical membrane of monolayered cultured NHMEE cells. Apical UTP-induced [Ca(2+)](i) was inhibited by 2-aminoethoxydiphenyl borate (2-APB) but not by ryanodine. UTP-induced mucin secretion was inhibited by a Ca(2+) chelating agent, BAPTA-AM, and was stimulated by ionomycin. UTP-induced mucin secretion was also suppressed by U73122 and 2-APB, while Calphostin C suppressed it to a small extent and PD98059 was ineffective. Caffeine also inhibited the UTP-induced [Ca(2+)](i) and mucin secretion. These results suggest that the P2Y(2) receptor is expressed in NHMEE cells, and plays a major role in modulating the [Ca(2+)](i) from the IP(3)-sensitive intracellular Ca(2+) store. UTP-induced mucin secretion in NHMEE cells is strongly dependent on Ca(2+)- and IP(3).

Calcium↗
PubMed2005

Genomic segments cloning and analysis of Cotesia plutellae polydnavirus using plasmid capture system.

Cotesia plutellae polydnaviruses (CpBV) has a segmented genome consisting of multiple circular double stranded DNAs. Recently, we have developed an easy, simple, and convenient system based on Tn7 transposition in order to clone genomic segments of CpBV in Escherichia coli cell and designated plasmid capture system (PCS). The PCS donor-S transferred a pUC19 origin of replication and an ampicillin resistance marker into CpBV genomic DNA by in vitro transposition. Through PCS system, we were able to clone 53 genomic clones ranging from 0.1 to 25.5 kb and further they were classified into 29 segments by their sizes and restriction endonuclease patterns. Among them, a complete nucleotide sequence of CpBV-S28 segment was determined and 10 putative genes were predicted from this segment. Interestingly, 9 of 10 putative ORFs had high level of similarities with catalytic domain of protein tyrosine phosphatase. Also, ORF2807 showed similarity with EP1-like proteins of C. congregata polydnavirus.

Chromosome Mapping↗
PubMed2005

Subsidence after anterior lumbar interbody fusion using paired stand-alone rectangular cages.

The authors conducted a study to determine at what stage after surgery the subsidence occurred, and to assess the relationships of radiographic fusion and the recurrence of symptoms with the development of subsidence. Ninety patients underwent a single-level anterior lumbar interbody fusion (ALIF) using paired stand-alone rectangular cages between November 2000 and June 2002. All patients had regular clinical or imaging follow-up for a minimum of 19 months (range 19-38 months, mean = 27 months). The ratio of male to female patients was 1:3.1. The patients' ages at the time of ALIF ranged from 25 to 72 years, with a mean of 53 years. The preoperative and postoperative intervertebral disc heights were serially measured by plain radiographs. The location of cage subsidence into the vertebral body and times until the presence of subsidence were also assessed. The mean preoperative intervertebral disc height was 11.6+/-3.1 mm, which spread immediately after surgery to 16.9+/-2.0 mm. This increase was statistically significant (P = 0.001). At the last follow-up visit, the mean intervertebral disc height had been reduced to 13.2+/-2.4 mm. Sixty-nine of 90 patients (76.7%) developed cage subsidence into the surrounding vertebral body. Subsidence was more often noted in the superior endplate above the cage with regard to the location of cage subsidence [superior endplate: 27 patients (39.1%), inferior endplate: 12 patients (17.3%), both: 30 patients (43.6%)]. The onset of subsidence varied from 0.25 to 8 months after surgery (median, 2.75 months). The 8-, 12-, and 16-week actuarial rates for developing cage subsidence were 38.9, 63.4, and 70.7%, respectively, when using the Kaplan-Meier method. There was no statistical correlation between the recurrence of symptoms (P = 0.3952) and radiographic fusion (P = 0.9518) with the log-rank test in development of subsidence. This study demonstrates that cage subsidence is an expected occurrence after ALIF using stand-alone rectangular cages. The 3- and 4-month actuarial rates for developing cage subsidence were 63.4 and 70.7%, respectively, and cage subsidence had no correlation with recurrence of symptoms and radiographic fusion in our study.

Adult↗
PubMed2005

Curative surgery for recurrent nasopharyngeal carcinoma via the infratemporal fossa approach.

OBJECTIVE: To determine the proper indications (and thus define good candidates) for the infratemporal fossa approach (ITFA) in the treatment of recurrent nasopharyngeal carcinoma (NPC). DESIGN: Retrospective analysis of 11 consecutive patients who had recurrent NPC after radiation therapy failure and were treated with curative surgery via the ITFA approach from July 1, 1993, to November 20, 1999. The mean follow-up was 32.5 months (range, 9-56 months). SETTING: Academic tertiary referral center. RESULTS: Patients who had a recurrent tumor confined to the Rosenmüller fossa (rT1; n = 3) or extending to the parapharynx (rT2; n = 3) maintained a clear surgical margin and were disease free. However, patients who had rT1 (n = 1) or rT2 (n = 1) tumors crossing the midline of the posterior nasopharyngeal wall had surgical margin involvement and their tumors recurred, and all patients with rT3 (n = 2) or rT4 (n = 1) tumors eventually died of the disease. CONCLUSIONS: Resection of recurrent NPC via ITFA is useful for tumors located in the Rosenmüller fossa with or without parapharyngeal extension. However, tumors extending to the contralateral nasopharyngeal mucosa and tumors at an advanced stage are not suitable indications for ITFA.

Adult↗
PubMed2005

Expression of Na+/H+ exchanger isoforms in normal human nasal epithelial cells and functional activity of Na+/H+ exchanger 1 in intracellular pH regulation.

CONCLUSIONS: Both the mRNA and protein of NHE1, -2 and -3 were expressed in NHNE cells. NHE1 is a major NHE isoform which is expressed in the basolateral membranes of NHNE cells. OBJECTIVE: Na+/H+ exchangers are ubiquitous plasma membrane transport proteins implicated in the maintenance of intracellular pH. The aim of this study was to examine the expression of Na+/H+ exchangers as a function of the differentiation of normal human nasal epithelial (NHNE) cells. In addition, we investigated the functional activity of the Na+/H+ exchanger 1 (NHE1) in basolateral membranes. MATERIAL AND METHODS: Cultured passage-2 NHNE cells were used. RNA and histological samples were collected on the day of confluence and on the 7th, 14th and 28th days after confluence in order to determine the effects of time. Cell lysates were collected on the day of confluence to investigate the presence of the proteins. Reverse transcriptase polymerase chain reaction and Western blotting were performed to investigate the presence of mRNA and protein, respectively. The functional activity of NHE1 was examined using 3-methylsulfonyl-4-piperidinobenzoyl guanidine methanesulfonate (HOE694), an NHE1-specific inhibitor, on the day of confluence. RESULTS: The NHE1 mRNA expression level did not change as a function of differentiation. However, the NHE2 mRNA expression levels increased on the 7th, 14th and 28th days after confluence. The NHE3 mRNA expression levels increased on the 14th and 28th days after confluence. Western blot analysis confirmed the expression of NHE1 (91 kDa), NHE2 (90 kDa) and NHE3 (93 kDa). In addition, HOE694 inhibited basolateral NHE activity by 68% at 1 microM and by 85% at 5 microM in the NHNE cells.

Blotting, Western↗
PubMed2005

IL-1beta promotes the ciliogenesis of human middle ear epithelial cells: possible linkage with the expression of mucin gene 8.

CONCLUSIONS: These findings suggest that IL-1beta, increases ciliogenesis in NHMEE cells and that MUC8 protein may play a role in this process. OBJECTIVES: The morphology of the middle ear epithelium changes under various pathologic conditions. We compared the density of ciliated cells and the level of mucin gene 8 (MUC8) mRNA in the middle ear epithelial cells of mucoid otitis media (MOM) patients with those of normal controls. We also investigated the effect of IL-1beta on the ciliogenesis and expression of MUC8 mRNA in cultured normal human middle ear epithelial (NHMEE) cells. In addition, we localized the MUC8 protein in cultured NHMEE cells. MATERIAL AND METHODS: The surface morphology of NHMEE cells was examined using scanning electron microscopy. Reverse transcriptase polymerase chain reaction was performed to determine the level of MUC8 mRNA expression. After synthesis of MUC8 polyclonal antibody, we performed immunohistochemical staining. RESULTS: The density of ciliated cells was increased in the middle ear epithelium of both MOM patients and IL-1beta-treated cultures. Similarly, the expression of MUC8 was increased in both cases. MUC8 antibody was primarily stained on the ciliated cells of NHMEE cells.

Case-Control Studies↗