Biomedical subjects

S K Choi

Publications and source records attributed to S K Choi.

At least 73 records · Page 4Linked to original sources

PubMed1998

An 8 kb nucleotide sequence at the 3' flanking region of the sspC gene (184 degrees) on the Bacillus subtilis 168 chromosome containing an intein and an intron.

As part of the Bacillus subtilis genome sequencing project, we determined the complete nucleotide sequence of an 8000-bp fragment downstream of the sspC gene (184 degrees) of the B. subtilis 168 chromosome. The sequence analysis shows that the sspC gene is located inside of the SP beta region, which differs from the current genetic map of B. subtilis 168. This region contains 12 putative ORFs (yojQ through yojZ and sspC). A homology search for the deduced products of the ORFs shows significant similarities to enzymes involved in deoxyribonucleotide metabolism: ribonucleotide reductase (Nrd) E, NrdF, thioredoxin and dUTPase. Interestingly, this DNA fragment includes two split genes, yojP containing conserved motifs of an intein and yojQ and yojS with an 808-bp intervening sequence for a putative intron structure. In addition, the yojR gene includes a putative new DNA replication terminator.

Amino Acid Sequence↗

PubMed1998

Potential antitumor alpha-methylene-gamma-butyrolactone-bearing nucleic acid base. 3. Synthesis of 5'-methyl-5'-[(6-substituted-9H-purin-9-yl)methyl]-2'-oxo-3'- methylenetetrahydrofurans.

Search for a new alpha-methylene-gamma-butyrolactone-bearing 6-substituted purine as a potential antitumor agent has led to synthesize seven, hitherto unreported, 5'-Methyl-5'-[(6-substituted-9H-purin-9-yl)methyl]-2'-oxo-3'- methylenetetrahydrofurans (H, Cl, I, CH3, NH2, SH, > C=O) (6a-g). These include 5'-Methyl-5'-[(9H-purin-9-yl)methyl]-2'-oxo-3'-methylenetetrahydrofur ans (6a), 5'-Methyl-5'-[(chloro-9H-purin-9-yl)methyl]-2'-oxo-3'- methylenetetrahydrofurans (6b), 5'-Methyl-5'-[(6-iodo-9H-purin-9-yl) methyl]-2'-oxo-3'-methylenetetrahydrofurans (6c), 5'-Methyl-5'-[(6-methyl-9H-purin-9-yl) methyl]-2'-oxo-3'-methylenetetrahydrofurans (6d), 5'-Methyl-5'-[(9H-adenin-9-yl)methyl]-2'-oxo-3-methylenetetrahy drofurans (6e), 5'-Methyl-5'-[(6-mercapto-9H-purin-9-yl) methyl]-2'-oxo-3'-methylenetetrahydrofurans (6f) and 5'-Methyl-5'-[(9H-hypoxanthin-9-yl)methyl]-2'-oxo-3'- methylenetetrahydrofurans (6g) which were made by the Reformatsky-type reaction of ethyl alpha-(bromomethyl) acrylate with the corresponding (6-substituted-9H-purin-9-yl)-2-propanone intermediates (5a-g). These ketone intermediates 5a-g, 1-(9H-purin-9-yl)-2-propanone (5a), 1-(6-chloro-9H-purin-9-yl)-2-propanone (5b), 1-(6-iodo-9H-purin-9-yl)-2-propanone (5c), 1-(6-methyl-9H-purin-9-yl)-2-propanone (5d), 1-(9H-adenin-9-yl)-2-propanone (5e), 1-(6-mercapto-9H-purin-9-yl)-2-propanone (5f), and 1-(9H-hypoxanthin-9-yl)-2-propanone (5g) were directly obtained by the alkylation of the 6-substituted purine bases with the chloroacetone in the presence of K2CO3 (or NaH) under DMF (or DMSO). The preliminary in vitro cytotoxicity assay for the synthetic alpha-methylene-gamma-butyro-lactone compounds (6a-g) were determined against three cell lines (PM-3A, P-388, and K-562) and showed the moderate antitumor activity (IC50 ranged from 1.4 to 4.3 micrograms/ml) with the compound 5'-methyl-5'-[(9H-hypoxanthin-9-yl)methyl]-2'-oxo-3'- methylenetetrahydrofuran (6g) showing the least antitumor activity.

4-Butyrolactone↗

PubMed1998

Synthesis and antitumor evaluation of cis-(1,2-diaminoethane) dichloroplatinum (II) complexes linked to 5- and 6-methyleneuracil and -uridine analogues.

The search for platinum (II)-based compounds with improved therapeutic properties was prompted to design and synthesize a new family of water-soluble, third generation cis-diaminedichloroplatinum (II) complexes linked to uracil and uridine. Six heretofore unreported uracil and uridine-platinum (II) complexes are; [N-(uracil-5-yl-methyl)ethane-1,2-di-amine]dichloroplatinum (II) (3a), [N-(uracil-6-yl-methyl)ethane-1,2-diamine] dichloroplatinum (II) (3b), ¿[N-(2', 3',5'-tri-O-acetyl)uridine-5-yl-methyl] ethane-1,2-diamine¿dichloroplatinum (II) (6a), ¿[N-(2',3', 5'-tri-O-acetyl) uridine-6-yl-methyl)ethane-1,2-diamine¿dichloroplatinum (II) (6b), [N-(uridine-5-yl-methyl)ethane-1,2-diamine]dichloroplatinum (II) (7a), [N-(uridine-6-yl-methyl)ethane-1,2-diamine]dichloroplatinum (II) (7b). These analogues were prepared from the key starting materials, 5-chloromethyluracil (1a) and 6-chloromethyluracil (1b) which were reacted with ethylenediamine to afford the respective 5-[(2-aminoethyl)amino] methyluracil (2a) and 6-[(2-aminoethyl)amino]methyluracil (2b). The cis-platin complexes 3a and 3b were obtained through the reaction of the respective 2a and 2b with potassium tetrachloroplatinate (II). The heterocyclic nucleic acid bases 1a and 1b were efficiently introduced on the beta-D-ribose ring via a Vorbruggen-type nucleoside coupling procedure with hexamethyldisilazane, trimethylchlorosilane and stannic chloride under anhydrous acetonitrile to yield the stereospecific beta-anomeric 5-chloromethyl-2',3',5'-tri-O-acetyluridine (4a) and 6-chloromethyl-2',3',5'-tri-O-acetyluridine (4b), respectively. The nucleosides 4a and 4b were coupled with ethylenediamine to provide the respective 5-[(amino-ethyl)amino]methyl-2',3',5'-tri-O-acetyluridine (5a) and 6-[(aminoethyl)amino] methyl-2',3',5'-tri-O-acetyluridine (5b). The diamino-uridines 5a and 5b were reacted with potassium tetrachloroplatinate (II) to give the novel nucleoside complexes, 6a and 6b, respectively which were deacetylated into the free nucleosides, 7a and 7b by the treatment with CH3ONa. The cytotoxic activities were evaluated against three cell lines (FM-3A, P-388 and J-82) and none of the synthesized compounds showed any significant activity.

Animals↗

PubMed1998

Induction of differentiation of the human histocytic lymphoma cell line U-937 by hypericin.

Hypericin, a photosensitizing plant pigment, was found to be a potent inducer of differentiation of human myeloid leukemia U-937 cells. At a concentration of 0.2 microM, hypericin exhibited 50% growth inhibition. An effect on cell differentiation by hypericin was assessed by its ability to induce phagocytosis of latex particles, and to reduce nitroblue tetrazolium (NBT). Approximately 51% of 0.2 microM hypericin-treated cells were stained with NBT and 63% showed phagocytic activity. In order to establish whether hypericin induces differentiation of U-937 cells to macrophage or granulocyte, esterase activities and cell sizes were measured. When U-937 cells were treated with 0.2 microM and 0.15 microM of hypericin, the alpha-naphthyl acetate esterase activity was increased by 38.4% and 48.1%, respectively, but naphthol AS-D chloroacetate esterase activity was not influenced. The size of hypericin-treated cells in terms of cell mass was larger than that observed in untreated cells as determined by flow cytometry. Protein kinase C (PKC) inhibitor, NA-382, decreased the NBT reducing activity of hypericin, whereas a cAMP-dependent protein kinase A (PKA) inhibitor, H-89, did not show any influence on the differentiation. These results indicate that hypericin triggers differentiation toward monocyte/macrophage lineage by PKC stimulation.

Anthracenes↗

PubMed1998

Polysaccharide K induces Mn superoxide dismutase (Mn-SOD) in tumor tissues and inhibits malignant progression of QR-32 tumor cells: possible roles of interferon alpha, tumor necrosis factor alpha and transforming growth factor beta in Mn-SOD induction by polysaccharide K.

Previously we reported the malignant progression of QR-32, a regressor-type tumor clone, following co-implantation with foreign bodies (gelatin sponge or plastic plate) in normal syngeneic C57BL/6 mice. We also reported that the progression of QR-32 cells by a gelatin sponge was significantly inhibited in the mice administered polysaccharide K (PSK) and that PSK induced an increase of radical scavengers, especially manganese superoxide dismutase (Mn-SOD), locally at the site of tumor tissues. In this study, to reveal the possible mechanism by which PSK induced Mn-SOD in the tumor tissues, we examined the mRNA expression and protein levels of inflammatory cytokines in the tissues. We found that mRNAs of tumor necrosis factor alpha (TNFalpha) and interleukin-1alpha (IL-1alpha) were considerably expressed in both PSK-treated and phosphate-buffered-saline-treated tumors, and that the mRNA expression and protein level of interferon gamma (IFNgamma) increased in the tumor tissues treated with PSK. In vitro treatment of QR-32 cells with IFNgamma did not significantly increase the production of Mn-SOD; however, the combination of IFNgamma with TNFalpha increased the Mn-SOD production more effectively than did any of the cytokines used singly. Furthermore, we observed the down-regulation of the mRNA expression and protein level of transforming growth factor beta (TGFbeta) in the tumor tissues treated with PSK, and that in vitro treatment of QR-32 cells with TGFbeta decreased the production of Mn-SOD. These results suggest that PSK suppresses the progression of QR-32 cells by increasing Mn-SOD via the modulation of inflammatory cytokines; that is, by decreasing TGF-beta and increasing IFN-gamma.

Adjuvants, Immunologic↗

PubMed1998

Single hair grafting for the treatment of vitiligo.

BACKGROUND: Vitiligo is a disease of unknown cause, and many medical and surgical therapeutic methods are used to treat it. OBJECTIVE: Our purpose was to evaluate the effectiveness of single hair grafting in patients with vitiligo. METHODS: Single hairs were grafted into vitiliginous areas of 21 patients. The diameter of the spreading pigmentation was evaluated periodically. RESULTS: Perifollicular repigmentation around the grafted hair was observed in 15 patients (71%) within 2 to 8 weeks. The diameter of the spreading pigmentation ranged from 2 to 10 mm during a 12-month follow-up period. In cases of generalized vitiligo, perifollicular pigmentation was seen in one of four patients (25%), whereas it was observed in 14 of 17 patients (82%) with localized/segmental vitiligo. Transformation of depigmented hairs into pigmented ones occurred in five patients. CONCLUSION: Single hair grafting appears to be an effective method for treating localized/segmental vitiligo, especially on hairy parts of the skin, including the eyelids and eyebrows, and for small areas of vitiligo.

Adult↗

PubMed1998

Does delayed operation for pediatric ureteropelvic junction obstruction cause histopathological changes?

PURPOSE: We studied histopathological changes in kidneys with demonstrable ureteropelvic junction obstruction in relation to patient age, differential renal function and urinary tract infection. MATERIALS AND METHODS: Renal biopsy was performed in 42 children (44 kidneys) with a mean age of 3 years 6 months who underwent open pyeloplasty due to ureteropelvic junction obstruction. Each specimen was examined for reversible inflammatory cell infiltration and irreversible change, including interstitial fibrosis, arteriolar thickening and glomerular sclerosis. Each pathological finding was scored 0 to 3 in increasing grades of severity, and correlated with patient age, differential renal function and history of urinary tract infection. RESULTS: Of the 44 kidneys 20 (45%) had irreversible change. Correlation study revealed no association between patient age and histological findings, and there was no statistically significant difference in any histopathological category regardless of age. Differential renal function correlated with inflammatory cell infiltration and interstitial fibrosis. There were significantly worse histopathology scores in all categories when differential renal function was less than 30 versus 40% or greater. Interstitial fibrosis was significantly worse in the 30 to 40% group than in the greater than 40% group. The histopathological score of interstitial fibrosis was significantly higher in patients with than without urinary tract infection. CONCLUSIONS: Early correction in infants with ureteropelvic junction obstruction may not be necessary when initial differential renal function is greater than 40%. However, any decrease in differential renal function or recurrent urinary tract infections despite antibiotic prophylaxis warrant surgical correction of obstruction.

Adolescent↗

PubMed1998

Immunoreactivity of androgen receptor protein in sexually dimorphic spinal motonucleus in neonatal male rats.

The spinal motonucleus of the genitofemoral nerve regulating scrotal temperature can also be related to prenatal and neonatal testicular descent by gubernacular change in rats, and a sexually dimorphic-like bulbocavernosus/dorsolateral motonucleus. There is a hypothesis that neonatal androgen affects these motonuclei, and induces development of sexual organs through neural stimulation. Until now, the accumulation of isotope-labelled androgen and the immuno-reactivity of androgen receptor protein in each sexually-dimorphic spinal motonucleus have been revealed in adult rats but they have not been established in rats during neonatal periods. To investigate the presence of the androgen receptor in spinal sexually-dimorphic motonuclei in the neonatal period, we evaluated the androgen receptor immunoreactivity of these motonuclei. In Sprague-Dawley male rats, the lumbar spinal cords were resected at postnatal days 3, 10 and 30, and stained immunohistochemically using polyclonal antibody of androgen receptor protein. The immunoreactivity of androgen receptor protein was observed in the cells of the genitofemoral motonucleus from the 13th thoracic to the 2nd lumbar spinal cord and the bulbocavernosus/dorsolateral motonucleus was observed from the 4th to 5th lumbar spinal cord in all age groups. The proportional areas of both motonuclei at days 3 and 10 on cross-section were larger than at day 30. The motonuclei at days 3 and 10 were similar in all age groups. With the above results, the presence of androgen receptor protein was confirmed in the genitofemoral and bulbocavernosus/dorsolateral motonucleus from neonate to day 30. The larger proportional area of these motonuclei in neonates may indicate an active role for these motonuclei during the neonatal period. Although the immunoreactivity does not directly imply the presence of a functional receptor, neonatal androgen could be responsible for the development of sexual organs through the spinal motonucleus.

Animals↗

PubMed1998

Acute scrotum in 7 cases of Schoenlein-Henoch syndrome.

Schoenlein-Henoch syndrome (SHS), one of the manifestations of systemic vasculitis, usually involves the skin, gastrointestinal tract, joints and kidney. Since the involvement of male genitalia is very rare and there is little mention of it in textbooks, doctors have a tendency to neglect this finding in SHS. Unless there is a confirming diagnosis, it is easily mistaken for testicular torsion and the patients undergo unnecessary operations because they complain of unbearable scrotal pain. SHS is not uncommon in Korea, but hardly any cases of scrotal involvement are found. We have experienced 7 cases of acute scrotum associated with SHS admitted to Severance Hospital, Yonsei University College of Medicine during the last 20 years; 2 underwent operation and 5 received conservative treatment only.

Acute Disease↗

PubMed1997

The complete genome sequence of the gram-positive bacterium Bacillus subtilis.

Bacillus subtilis is the best-characterized member of the Gram-positive bacteria. Its genome of 4,214,810 base pairs comprises 4,100 protein-coding genes. Of these protein-coding genes, 53% are represented once, while a quarter of the genome corresponds to several gene families that have been greatly expanded by gene duplication, the largest family containing 77 putative ATP-binding transport proteins. In addition, a large proportion of the genetic capacity is devoted to the utilization of a variety of carbon sources, including many plant-derived molecules. The identification of five signal peptidase genes, as well as several genes for components of the secretion apparatus, is important given the capacity of Bacillus strains to secrete large amounts of industrially important enzymes. Many of the genes are involved in the synthesis of secondary metabolites, including antibiotics, that are more typically associated with Streptomyces species. The genome contains at least ten prophages or remnants of prophages, indicating that bacteriophage infection has played an important evolutionary role in horizontal gene transfer, in particular in the propagation of bacterial pathogenesis.

Bacillus subtilis↗

PubMed1997

Establishment and characterization of a highly tumorigenic human diploid endometrial cancer cell line.

A new cell line designated CUME-1 has been established from a poorly differentiated endometrial adenocarcinoma of the uterus. This cell line grew well without interruption for more than 88 months and 110 serial passages were successively carried out. The cells were highly tumorigenic in nude mice (85%). Repeated karyotype analyses from early (4th) to late (55th) passages of this cell line revealed a diploid stable clone in each passages without any noticeable structural or numerical aberrations. But from the 80th passage, a subpopulation with reciprocal translocation between chromosomes 1q and 9q consistently appeared and was observed in about 30% of the cells. This cell line is one of the rare examples of experimentally proved tumorigenic cells of human solid tumor origin that retains the diploid karyotype in vitro. HLA typing indicated the presence of DR4, DR13, DQ3 and DQ6. Cytosol estrogen and progesterone receptors were found both in fresh primary tumor and in this cell line. Gonadotropin-releasing hormone (Gn-RH) receptor mRNA was detected by reverse transcription-polymerase chain reaction (RT-PCR) in cultured cells. Using the single-strand conformation polymorphism (SSCP) technique, we have screened CUME-1 cells for p53 mutation in exons 4 to 9. No mobility shift was observed. This cell line may be useful in studying the in vitro chromosomal evolution of the cell line and the in vivo properties of human endometrial adenocarcinoma.

Adenocarcinoma↗

PubMed1997

Structure-binding relation of philanthotoxins from nicotinic acetylcholine receptor binding assay.

Philanthotoxins are noncompetitive inhibitors of the nicotinic acetylcholine receptor and the various glutamate receptors. Analogues carrying photoaffinity labels, fluorine atoms for solid-state NMR studies of ligand/receptor interaction, and large head groups such as porphyrins and planar bulky aromatic rings (BIG analogues) for clarifying mode of entry and orientation of analogues in receptors have been synthesized, assayed against the nicotinic acetylcholine receptor, and brief comments are given for the assay results.

Amino Acids↗

PubMed1997

A randomized animal study evaluating the efficacies of locally delivered heparin and urokinase for reducing in-stent restenosis.

BACKGROUND: In-stent restenosis is primarily due to neointimal hyperplasia. Results from recent nonrandomized studies suggest that local delivery of heparin or urokinase to the site of angioplasty or stenting results in a lower rate of restenosis. OBJECTIVE: To determine whether local delivery of heparin or urokinase reduces in-stent restenosis. METHODS AND RESULTS: Thirty-three pigs were assigned randomly to one of three groups: controls (n = 9) administered local saline infusion, the heparin group (n = 15) administered local heparin (6000 u/10 min), and the urokinase group (n = 9) administered local urokinase (250000 u/10 min), via a local delivery catheter (Dispatch) at the site of subsequent stent implantation. Prior to local delivery, all of the animals were subjected to balloon injury (balloon:artery diameter ratio approximately or = 1.3) to facilitate intramural drug impregnation. After local therapy, one Palmaz-Schatz stent (mean stent: artery diameter ratio approximately or = 1.25) was implanted within the left anterior descending coronary artery. The degree of neointimal hyperplasia was evaluated 4 weeks later by angiography (as the maximal percentage diameter stenosis) and histology (as the maximal neointimal area stenosis). We found no difference in percentage diameter stenosis (46 +/- 18% control, 42 +/- 27% heparin group, and 37 +/- 20% urokinase group, P = 0.7) and corrected neointimal area (1.06 +/- 0.42 mm2 control, 0.94 +/- 0.29 mm2 heparin, and 0.88 +/- 0.26 mm2 urokinase group, P = 0.7) among groups at follow-up. The activated clotting time rose slightly for heparin-treated animals, suggesting that systemic delivery had occurred, whereas fibrinogen levels did not change in urokinase-treated animals. CONCLUSIONS: Local deliveries of heparin and urokinase via the Dispatch catheter, at the chosen dosages, do not reduce in-stent neointimal hyperplasia in this porcine model.

Animals↗

PubMed1997

Microsatellite instability in Korean patients with gastric adenocarcinoma.

OBJECTIVES: Microsatellites are short repeated oligonucleotide sequences found throughout the human genome. High mutation rates in microsatellite sequences have been found in tumors from patients with hereditary non-polyposis colorectal carcinoma and some sporadic carcinomas. However, little information is available regarding RER-positive phenotype in gastric carcinomas, particularly in terms of age of onset and other pathologic features, such as histologic types, degree of differentiation, location or stage of the carcinoma. METHODS: To obtain a better understanding of the molecular mechanism of gastric carcinogenesis, microsatellite instability was examined at 6 gene loci (D2S71, D2S119, D3S1067, D6S87, D8S87, D11S905) in 77 gastric carcinomas (40 cases of young patients and 37 cases of elderly patients). RESULTS: RER-positive phenotypes were found in 17 (22.1%) of 77 cases. In young patients (under 40 years) RER-positive phenotype was found in 9 (22.5%) of 40 cases, and in elderly patients 8 (21.6%) of 37 cases. Moderately differentiated carcinoma revealed a significantly high frequency of RER-positive phenotype than well differentiated carcinoma(p < 0.001). Tumors arising from the middle third (p < 0.001) or lower third (p < 0.001) revealed higher frequency of RER-positive phenotype than the tumors arising from the upper third of the stomach. The RER-positive phenotype was not significantly affected by the sex, histologic type or stage of carcinoma. CONCLUSION: RER-positive phenotype occurs frequently in gastric carcinoma, although the frequency of RER-positive phenotype between young and elderly patient was not significantly different. Thus, the acquisition of RER-positive phenotype might be an early event in gastric carcinogenesis.

Adenocarcinoma↗

PubMed1996

Dissociation of the cellulosome of Clostridium thermocellum in the presence of ethylenediaminetetraacetic acid occurs with the formation of trucated polypeptides.

The cellulosome of Clostridium thermocellum JW20 consists of 14-26 different polypeptides as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The intact cellulosomes hydrolyzes crystalline cellulose in the presence of Ca2+ and thiols. This activity is inhibited by ethylenediaminetetraacetic acid (EDTA). Ca is incorporated into the cellulosome and tightly bound as demonstrated using 45Ca added to the growth medium. Upon incubation in 50 mM Tris (pH 7.5), 0.1 M NaCl, and 5 mM EDTA at 37 degrees C, Ca is released from the cellulosome, which disintegrates into polypeptides. The SDS-PAGE pattern of cellulosomal polypeptides is remarkably different after the EDTA treatment when compared to this pattern of untreated cellulosomes. Polypeptide bands corresponding to molecular masses of 160, 98, 76, 91, and 54 kDa disappear, and new bands of masses 150, 132, 91, 71, 57, and 46 kDa appear. N-terminal analyses of the 98, 76, 91, and 71 kDa polypeptides show that the 91 and 71 kDa polypeptides are truncated products of the 98 and 76 kDa polypeptides, respectively. The 76 and 71 kDa polypeptides correspond to CelS [Wang, W. K., Kruus K., & Wu, J. H. D. (1993) J. Bacteriol. 175, 1293-1302]. The 71 kDa polypeptide is formed from the 76 kDa polypeptide during the EDTA treatment, by a cleavage that occurs at asparagine residue 681. It involves the removal of 60 amino acid residues from the C-terminal end. All catalytic subunits so far characterized contain an asparagine residue corresponding to residue 681 of CelS. This residue is part of the conserved duplicated region found in catalytically active subunits, and it is postulated that several of these subunits also are truncated by the EDTA treatment. The polypeptides truncated by the EDTA treatment reduced Ca binding capacities compared to their native subunits, indicating a Ca-binding site within the conserved duplicated region. This region has been implicated in the binding of the catalytic peptides to the scaffolding polypeptide CipA, which is a structural protein of the cellulosome and has a strong affinity for calcium.

Amino Acid Sequence↗

PubMed1996

Structural role of calcium for the organization of the cellulosome of Clostridium thermocellum.

The cellulosome of Clostridium thermocellum is a multipolypeptide complex of structural and catalytic subunits. Several of the catalytic subunits have at the carboxyl end a conserved duplicated region (CDR) which interacts with internally repeated elements (IREs) of scaffolding subunits such as CipA. This interaction requires calcium. The two parts of the CDR region here designated CDR1 and CDR2 (closest to the carboxyl end) each consist of about 20 amino acids residues. As shown in our previous paper [Choi, S.K., & Ljungdahl, L.G. (1996) Biochemistry 35, 4897-4905], treatment of the cellulosome with ethylenediaminetetraacetic acid (EDTA) under aerobic conditions disintegrates the cellulosome with formation of truncated catalytic subunits. The cleavage is at a specific asparagine residue located within CDR1 and occurs with complete loss of CDR2. Two branched peptides containing the amino acid sequences of CDR1 and CDR2 (designated bCDR1 and bCDR2) were synthesized, and specific antibodies were raised against them. These antibodies did not cross react with bCDR1 or bCDR2, respectively. After sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting, it was observed that about 15 subunits of the cellulosome reacted with anti-bCDR1 and anti-bCDR2. In a similar experiment with EDTA-treated cellulosomes, these subunits reacted with anti-bCDR1 but not with anti-bCDR2, showing that they lost the bCDR2 epitope and were truncated. The peptide bCDR1 binds calcium, whereas bCDR2 does not. Furthermore, bCDR1 but not bCDR2 binds to CipA, presumably at IRE regions. This binding requires calcium. A model is proposed for the binding of the catalytic subunits to CipA which involves CDR1, an IRE, and calcium.

Amino Acid Sequence↗

PubMed1996

Patterns of anismus and the relation to biofeedback therapy.

PURPOSE: A study was undertaken to assess physiologic characteristics and clinical significance of anismus. Specifically, we sought to assess patterns of anismus and the relation of these findings to the success of therapy. METHODS: Sixty-eight patients were found to have anismus based on history and diagnostic criteria including anismus by defecography and at least one of three additional tests: anorectal manometry, electromyography, or colonic transit time study. Interpretation of defecography was based on the consensus of at least three of four observers. Anal canal hypertonia (n = 32) was defined when mean and maximum resting pressures were at least 1 standard deviation higher than those in 63 controls. There were two distinct defecographic patterns of anismus: Type A (n = 26), a flattened anorectal angle without definitive puborectalis indentation but a closed anal canal; Type B (n = 42), a clear puborectalis indentation, narrow anorectal angle, and closed anal canal. Outcomes of 57 patients who had electromyographybased biofeedback therapy were reported as either improved or unimproved at a mean follow-up of 23.7 (range, 6-62) months. These two types of anismus were compared with biofeedback outcome to assess clinical relevance. RESULTS: Patients with Type A anismus showed greater perineal descent at rest (mean, 5.1 vs. 3.5 cm; P < 0.01), greater dynamic descent between rest and evacuation (mean, 2.7 vs. 1.4 cm; P < 0.01), greater difference of anorectal angle between rest and evacuation (mean, 14.6 vs. -3.1 degrees; P < 0.001), higher mean resting pressure (mean, 77.1 vs. 62.8 mmHg; P < 0.05), lower mean squeeze pressure (58.8 vs. 80.7 mmHg; P < 0.05), and a higher incidence of anal canal hypertonia (69.2 vs. 33.3 percent; P < 0.01) than did patients with Type B anismus. Only 25 percent of patients who had Type A anismus with anal canal hypertonia were improved by biofeedback therapy. Conversely, 86 percent of patients with Type B anismus without anal canal hypertonia were successfully treated with biofeedback (P < 0.001; Fisher's exact test). CONCLUSIONS: These two distinct physiologic patterns of anismus correlate with the success of biofeedback treatment. Therefore, knowledge of these patterns may help direct therapy.

Adolescent↗

PubMed1996

Studies of gas-jet assisted RF-glow discharge atomic absorption spectrometry.

The gas jet assisted glow discharge source has been employed for the RF-glow discharge atomic absorption spectrometry (RF-GDAAS). Data are described to illustrate the role of discharge power, pressure as well as gas flow rate on the sample loss rate, absorbance and self-bias potential. Results show that the optimum discharge conditions depend not only on the pressure and discharge power but also on the gas flow rate. The absorbance increases as much as 1 order of magnitude as the gas flow rate increases from 50 mL/min to 500 mL/min at a pressure of 3 mbar. The use of a gas-jet source allows the direct analysis of solids by RF-GDAAS.

Journal Article↗