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S J Suh

Publications and source records attributed to S J Suh.

15 recordsLinked to original sources
PubMed2001

Three functional isoforms of GAR-2, a Caenorhabditis elegans G-protein-linked acetylcholine receptor, are produced by alternative splicing.

We have previously isolated a cDNA clone from Caenorhabditis elegans that encodes a novel form of G-protein-linked acetylcholine receptor, termed GAR-2. GAR-2 is similar to but pharmacologically distinct from muscarinic acetylcholine receptors. Here we report the identification of two gar-2 cDNA clones that are different from the previous one. These newly identified cDNAs encode polypeptides of 664 and 627 amino acids, whereas the previous one encodes a polypeptide of 614 amino acids. The three GAR-2 isoforms, which differ only in the third intracellular loop, arise from alternative splicing. Electrophysiological analyses using the Xenopus oocyte system showed that all three GAR-2 isoforms couple to the activation of G-protein-gated inwardly rectifying K+ (GIRK1) channel with similar drug specificity. Our results indicate that alternative splicing plays an important role in promoting molecular diversity of G-protein-linked acetylcholine receptors in C. elegans.

Alternative Splicing↗
PubMed2001

MR findings of the spinal paraganglioma : report of three cases.

Extraadrenal paragangliomas involving the spine is less common and usually takes the form of intradural compression of the cauda equina. The authors report three cases of spinal paragangliomas resulting in extradural spinal cord compression and their MR findings. The MR imaging revealed a well-demarcated extradural mass with low to intermediate signal intensity on T1-weighted images and intermediate to high signal intensity on T2-weighted images compared to paravertebral muscles. After Gd-DTPA administration, heterogeneous and intense enhancement was found. Multiple punctate and serpiginous structures of signal void due to high-velocity flow were noted around and within the tumors on all sequences. In one case, the signal void structures were well corresponded with feeding arteries on angiography. These may be the characteristic findings of the extraadrenal paraganglioma involving the spine.

Adult↗
PubMed2000

Role of RpoS and AlgT in Pseudomonas aeruginosa biofilm resistance to hydrogen peroxide and monochloramine.

The role of two sigma factors, AlgT and RpoS, in mediating Pseudomonas aeruginosa biofilm resistance to hydrogen peroxide and monochloramine was investigated. Two knock out mutant strains, SS24 (rpoS-) and PAO6852 (algT-), were compared with a wild type, PAO1, in their susceptibility to monochloramine and hydrogen peroxide. When grown as biofilms on alginate gel beads (mean untreated areal cell density 3.7 +/- 0.27 log cfu cm-2) or on glass slides (mean untreated areal cell density 7.6 +/- 0.9 log cfu cm-2), wild type bacteria exhibited reduced susceptibility to both antimicrobial agents in comparison with suspended cells. On alginate gel beads, all strains were equally resistant to monochloramine. rpoS- and algT- gel bead biofilms of 24-hour-old were more susceptible to hydrogen peroxide disinfection than were biofilms formed by PAO1. Biofilm disinfection rate coefficients for the two mutant strains were statistically indistinguishable from planktonic disinfection rate coefficients, indicating complete loss of biofilm resistance. While 48-hour-old algT- biofilm cells became resistant to hydrogen peroxide, 48-hour-old rpoS- biofilm cells remained highly susceptible. With the thicker biofilms formed on glass coupons, all strains were equally resistant to both hydrogen peroxide and monochloramine. It is concluded that while RpoS and AlgT may play a transient role in protecting thin biofilms from hydrogen peroxide, these sigma factors do not mediate resistance to monochloramine and do not contribute significantly to the hydrogen peroxide resistance of thick biofilms.

Alginates↗
PubMed2000

Characterization of GAR-2, a novel G protein-linked acetylcholine receptor from Caenorhabditis elegans.

We have previously identified two G protein-linked acetylcholine receptors (GARs), GAR-1 and GAR-3, in the nematode Caenorhabditis elegans. Whereas GAR-3 is a homologue of muscarinic acetylcholine receptors (mAChRs), GAR-1 is similar to but pharmacologically distinct from mAChRs. In the current work we isolated a new type of GAR using C. elegans genome sequence information. This receptor, named GAR-2, consists of 614 amino acid residues and has seven putative transmembrane domains. Database searches indicate that GAR-2 is most similar to GAR-1 and closely related to GAR-3/mAChRs. The overall amino acid sequence identities to GAR-1 and GAR-3 are approximately 32 and approximately 23%, respectively. When GAR-2 was coexpressed with the G protein-activated inwardly rectifying K(+) (GIRK1) channel in Xenopus oocytes, acetylcholine was able to evoke the GIRK current in a dose-dependent fashion. Oxotremorine, a classical muscarinic agonist, had little effect on the receptor, indicating that GAR-2 is pharmacologically different from mAChRs but rather similar to GAR-1. GAR-2 differs from GAR-1, however, in that it showed virtually no response to muscarinic antagonists such as atropine, scopolamine, and pirenzepine. Expression studies using green fluorescent protein reporter gene fusion revealed that GAR-2 is expressed in a subset of C. elegans neurons, distinct from those expressing GAR-1. Together with our previous reports, this study demonstrates that diverse types of GARs are present in C. elegans.

Acetylcholine↗
PubMed2000

"Daughter cyst" sign: a sonographic finding of ovarian cyst in neonates, infants, and young children.

OBJECTIVE: The purpose of this study was to assess the value of the "daughter cyst" sign, a sonographic finding of neonatal ovarian cysts, in differentiating ovarian cysts from other cystic masses in neonates, infants, and young children. SUBJECTS AND METHODS: In a prospective study, 23 neonates, infants, and young children (age range, 1 day to 36 months) with a lower abdominal cystic mass underwent sonography. We defined the daughter cyst sign as the presence of a small cyst along the wall of a cystic mass. The diagnosis of ovarian cyst was made when this sign was present. Detailed pathologic correlation was available in four ovarian cysts. The size, wall thickness, and contents of the cysts were also evaluated. RESULTS: The 23 cystic lesions included ovarian cyst (n = 11), lymphangioma (n = 3), enteric duplication cyst (n = 3), enteric cyst (n = 1), meconium pseudocyst (n = 2), hydrometrocolpos (n = 2), and urachal cyst (n = 1). The daughter cyst sign was seen in nine (82%) of 11 ovarian cysts but in none of the other cystic lesions. Sensitivity, specificity, and positive predictive value of the daughter cyst sign for differentiating ovarian cysts from other cystic lesions were 82%, 100%, and 100%, respectively. The daughter cyst corresponded to an ovarian follicle on pathologic examination. CONCLUSION: The daughter cyst sign is a specific sonographic finding for an ovarian cyst and may be useful in differentiating uncomplicated ovarian cysts from other cystic masses in neonates, infants, and young children.

Child, Preschool↗
PubMed1999

Effect of rpoS mutation on the stress response and expression of virulence factors in Pseudomonas aeruginosa.

The sigma factor RpoS (sigmaS) has been described as a general stress response regulator that controls the expression of genes which confer increased resistance to various stresses in some gram-negative bacteria. To elucidate the role of RpoS in Pseudomonas aeruginosa physiology and pathogenesis, we constructed rpoS mutants in several strains of P. aeruginosa, including PAO1. The PAO1 rpoS mutant was subjected to various environmental stresses, and we compared the resistance phenotype of the mutant to that of the parent. The PAO1 rpoS mutant was slightly more sensitive to carbon starvation than the wild-type strain, but this phenotype was obvious only when the cells were grown in a medium supplemented with glucose as the sole carbon source. In addition, the PAO1 rpoS mutant was hypersensitive to heat shock at 50 degrees C, increased osmolarity, and prolonged exposure to high concentrations of H2O2. In accordance with the hypersensitivity to H2O2, catalase production was 60% lower in the rpoS mutant than in the parent strain. We also assessed the role of RpoS in the production of several exoproducts known to be important for virulence of P. aeruginosa. The rpoS mutant produced 50% less exotoxin A, but it produced only slightly smaller amounts of elastase and LasA protease than the parent strain. The levels of phospholipase C and casein-degrading proteases were unaffected by a mutation in rpoS in PAO1. The rpoS mutation resulted in the increased production of the phenazine antibiotic pyocyanin and the siderophore pyoverdine. This increased pyocyanin production may be responsible for the enhanced virulence of the PAO1 rpoS mutant that was observed in a rat chronic-lung-infection model. In addition, the rpoS mutant displayed an altered twitching-motility phenotype, suggesting that the colonization factors, type IV fimbriae, were affected. Finally, in an alginate-overproducing cystic fibrosis (CF) isolate, FRD1, the rpoS101::aacCI mutation almost completely abolished the production of alginate when the bacterium was grown in a liquid medium. On a solid medium, the FRD1 rpoS mutant produced approximately 70% less alginate than did the wild-type strain. Thus, our data indicate that although some of the functions of RpoS in P. aeruginosa physiology are similar to RpoS functions in other gram-negative bacteria, it also has some functions unique to this bacterium.

Alginates↗
PubMed1995

Sonographic diagnosis of paraovarian cysts: value of detecting a separate ipsilateral ovary.

OBJECTIVE: The purpose of this study was to determine the frequency with which sonographic detection of a normal separate ipsilateral ovary enables the diagnosis of paraovarian cysts. MATERIALS AND METHODS: We reviewed the initial sonographic reports, sonograms, and medical records of 42 patients with surgically proved paraovarian cysts. All sonograms were obtained with a 3.5-MHz transabdominal probe. The location, size, shape, wall thickness, internal echoes of the cyst, and visualization or nonvisualization of the ipsilateral ovaries were recorded during sonographic examination. RESULTS: Forty-six paraovarian cysts were identified in 42 patients. One patient had bilateral cysts, and one had multiple (four) unilateral cysts. A teratoma in one patient and an ovarian cyst in another coexisted with a paraovarian cyst in the same adnexa. With the exception of these two, 31 (76%) of 41 ovaries abutted by cysts were detected. All detectable ovaries were normal. With one exception, all cysts were thin walled and unilocular, and 43 of 46 were anechoic. During surgery, two patients were found to have cyst torsion, two were found to have papillary serous cystadenoma, and one was found to have both. CONCLUSION: Unlike the findings of previous reports, our results indicate that most patients with paraovarian cysts have a separate, normal ipsilateral ovary that can be detected easily by means of transabdominal sonography, thus aiding in distinguishing paraovarian from true ovarian cysts.

Adult↗
PubMed1993

Cloning, sequencing and overexpression of cobA which encodes ATP:corrinoid adenosyltransferase in Salmonella typhimurium.

The cobA gene of Salmonella typhimurium was cloned, sequenced and overexpressed. A 990-bp HpaI-SacI fragment was cloned into the multiple cloning site of plasmid pSU19, an intermediate-copy-number vector. DNA sequence analysis established that cobA is 588 bp in length and codes for a protein with a predicted molecular weight of 21.7 kDa. However, the CobA protein expressed from the T7 promoter migrated as a 25-kDa protein on SDS-polyacrylamide gels. A high degree of identity at the amino acid sequence level was established between the CobA, Pseudomonas denitrificans CobO and Escherichia coli BtuR proteins. P. denitrificans CobO has been shown to be a ATP:corrinoid adenosyltransferase enzyme. Based on the similarities between CobO and CobA, and the phenotypes of cobA mutants, we suggest that CobA is the ATP:corrinoid adenosyltransferase of S. typhimurium.

Alkyl and Aryl Transferases↗
PubMed1992

Childhood intussusception: US-guided hydrostatic reduction.

Over a 30-month period, real-time ultrasound (US) was performed in 116 children with suspected intussusception. US findings were positive in all 75 cases of intussusception. Except in one case of transient small-bowel intussusception, the authors immediately attempted US-guided hydrostatic reduction in all cases. Reduction was successful in 63 cases (85%), as demonstrated with US and resolution of signs and symptoms of intussusception. Negative sonograms were confirmed with clinical follow-up. Among 11 failed cases, reduction with barium enema was attempted in six, but all attempts failed. No complications have occurred to date. The authors conclude that US is a reliable diagnostic screening modality in cases of suspected intussusception and that US-guided hydrostatic reduction is a promising technique in nonoperative treatment.

Child↗
PubMed1992

Pediatric gastric volvulus--experience with 7 cases.

Gastric volvulus, organoaxial or mesenterioaxial, is a rare condition in infancy and childhood. We experienced 7 cases of pediatric gastric volvulus, consisting of 3 cases of secondary gastric volvulus due to left diaphragmatic eventration or paraesophageal hernia and 4 cases of idiopathic gastric volvulus. Of 7 cases, five were organoaxial in type and two were mesenterioaxial. The main symptoms of secondary gastric volvulus were vomiting and respiratory difficulty whereas those of idiopathic gastric volvulus were abdominal distension and weight loss with or without failure to thrive. It may be suspected on plain abdominal radiographs and usually confirmed by upper gastrointestinal series. Upper gastrointestinal series in organaxial volvulus demonstrated characteristic findings such as reversal of the greater and lesser curvatures and two air-fluid levels. In mesenterioaxial volvulus, the stomach was rotated into inverted position with pyloroantral obstruction showing a beak appearance. The three patients with secondary volvulus underwent repair of associated defect with or without gastropexy and the 3 patients with idiopathic volvulus underwent anterior gastropexy or gastrostomy. In those with idiopathic gastric volvulus, there was no obvious cause such as laxity of the perigastric ligaments. The operative results were satisfactory except for the three patients with idiopathic gastric volvulus whose abdomen remained distended regardless of weight gain.

Child↗
PubMed1990

Right perirenal space. Computed tomography evidence of communication between the bare area of the liver.

Computed tomography (CT) images from one cadaver and 11 patients with perirenal fluid collection were reviewed to study whether the right perirenal space communicates with the bare area of the liver. CT of a cadaver obtained after meticulous right perirenal injection of contrast media showed that contrast media extended superiorly into the bare area of the liver. CT of 11 patients with right perirenal hemorrhage or infection showed that fluid collection within the right perirenal space continued upward, crossing the coronary ligament, extending into the bare area of the liver. The inferior vena cava were completely or partially surrounded by fluid. CT of two patients with bleeding hepatocellular carcinoma showed that blood in the bare area continued extending downward into the perirenal space. We conclude that the right perirenal space is open toward the bare area of the liver and fluid collection within one space may communicate with the other space across the coronary ligament.

Cadaver↗
PubMed1990

cobA function is required for both de novo cobalamin biosynthesis and assimilation of exogenous corrinoids in Salmonella typhimurium.

Salmonella typhimurium is able to synthesize cobalamin (B12) under anaerobic growth conditions. The previously described cobalamin biosynthetic mutations (phenotypic classes CobI, CobII, and CobIII) map in three operons located near the his locus (minute 41). A new class of mutant (CobIV) defective in B12 biosynthesis was isolated and characterized. These mutations map between the cysB and trp loci (minute 34) and define a new genetic locus, cobA. The anaerobic phenotype of cobA mutants suggests an early block in corrin ring formation; mutants failed to synthesize cobalamin de novo but did so when the corrin ring is provided as cobyric acid dicyanide or as cobinamide dicyanide. Under aerobic conditions, cobA mutants were unable to convert either cobyric acid dicyanide or cobinamide dicyanide to cobalamin but could use adenosylcobyric acid or adenosylcobinamide as a precursor; this suggests that the mutants are unable to adenosylate exogenous corrinoids. To explain the anaerobic CobI phenotype of a cobA mutant, we propose that the cobA gene product catalyzes adenosylation of an early intermediate in the de novo B12 pathway and also adenosylates exogenous corrinoids. Under anaerobic conditions, a substitute function, known to be encoded in the main Cob operons, is induced; this substitute function can adenosylate exogenous cobyric acid and cobinamide but not the early biosynthetic intermediate. The cobA gene of S. typhimurium appears to be functionally equivalent to the btuR gene of Escherichia coli.

Chromosome Mapping↗
PubMedDate not supplied

MR findings of secondary hemochromatosis: transfusional vs erythropoietic.

OBJECTIVE: The aim of this study was to demonstrate the MR characteristics of secondary hemochromatosis (transfusional versus erythropoietic). MATERIALS AND METHODS: Magnetic resonance images of five patients with transfusional (n = 3) or erythropoietic (n = 2) hemochromatosis were reviewed. RESULTS: The liver of all patients had low signal intensity in all pulse sequences. The spleen had low signal intensity in all patients with transfusional iron overload, but normal signal intensity in erythropoietic hemochromatosis, which had similar MR findings to idiopathic hemochromatosis. However, the pancreas had variable signal intensity. CONCLUSION: On MRI the signal intensity of the spleen may allow distinction between transfusional and erythropoietic hemochromatosis.

Adult↗
PubMedDate not supplied

Isolation of a unique membrane protein from Naegleria fowleri.

Naegleria fowleri, an amoeboflagellate, is the causative agent of Primary Amoebic Meningoencephalitis, a fulminating disease of the central nervous system. In order to elucidate the mechanisms of pathogenicity of this amoeba, a cDNA expression library was prepared from N. fowleri RNA. A specific protein was found to be expressed from a cDNA clone designated Mp2CL5. Northern blot analysis showed that the Mp2CL5 mRNA was expressed in pathogenic N. fowleri but was not expressed in non-pathogenic Naegleria species nor in Acanthamoeba. Western blot analysis using anti-N. fowleri antiserum demonstrated that IPTG-induced Escherichia coli Mp2CL5 expressed a 23-kDa recombinant protein. The Mp2CL5 recombinant protein was histidine-tagged and purified to homogeneity from E. coli. A polyclonal rabbit antiserum was prepared against the purified Mp2CL5 recombinant protein. This antibody was used to further characterize the Mp2CL5 native protein expressed by N. fowleri. Western blot analysis in conjunction with immunofluorescence microscopy demonstrated the presence of a native protein of 17 kDa on the plasma membrane of N. fowleri trophozoites. The native N. fowleri protein was expressed in the logarithmic phase of trophozoite growth and the production of this protein increased through the stationary phase of growth. Studies are in progress to examine further its role as a virulence factor.

Amebiasis↗