A new approach to assay endo-type carbohydrases: bifluorescent-labeled substrates for glycoamidases and ceramide glycanases

Glycoamidases and ceramide glycanases are important "endo-type" enzymes for structural elucidations of glycoconjugates as well as for construction of neoglycoconjugates. The assay methods currently available for these enzymes are tedious and do not permit continual assay of the enzyme activities. We modified a desialylated biantennary glycopeptide with 2-naphthylacetic acid at the N-terminus and at the non-reducing terminal galactosyl residues with mono-N-dansylethylenediamine, via a specific oxidation of the C-6 hydroxyl group with galactose oxidase. In such a substrate, the naphthyl fluorescence (lambda em = 335 nm) is quenched due to absorption of its emitted light by the dansyl group, which in turn results in emission of fluorescence (lambda ex = 520 nm) by the latter. However, when the link between the two fluorophores is severed by glycoamidase (PNGase), the energy transfer ceases to occur. Consequently the emission of the dansyl fluorescence and the quenching of naphthyl fluorescence diminish or disappear. Likewise, the energy transfer between the fluorophores in an alkyl lactoside containing a dansyl group at the terminal position of aglycon and a 2-naphthylmethyl group on the galactosyl residue is also eliminated by the glycosidic cleavage by a ceramide glycanase from American leech, Macrobdella decora, resulting in enhancement of the naphthyl emission and decrease in the dansyl emission. The substrates presented here permit continuous fluorescent monitoring of the enzymatic reaction. This allows precise analyses of enzyme kinetics not possible with the conventional assay methods for the endo-type enzymes which usually require separation of reaction products.

The 3'-terminal exon of the family of steroid and phenol sulfotransferase genes is spliced at the N-terminal glycine of the universally conserved GXXGXXK motif that forms the sulfonate donor binding site

The guinea pig estrogen sulfotransferase gene has been cloned and compared to three other cloned steroid and phenol sulfotransferase genes (human estrogen sulfotransferase, human phenol sulfotransferase, and guinea pig 3 alpha-hydroxysteroid sulfotransferase). The four sulfotransferase genes demonstrate a common outstanding feature: the splice sites for their 3'-terminal exons are identically located. That is, the 3'-terminal exon splice sites involve a glycine that constitutes the N-terminal glycine of an invariably conserved GXXGXXK motif present in all steroid and phenol sulfotransferases for which primary structures are known. This consistency strongly suggests that all steroid and phenol sulfotransferase genes will be similarly spliced. The GXXGXXK motif forms the active binding site for the universal sulfonate donor 3'-phosphoadenosine 5'-phosphosulfate. Amino acid sequence alignment of 19 cloned steroid and phenol sulfotransferases starting with the GXXGXXK motif indicates that the 3'-terminal exon for each steroid and phenol sulfotransferase gene encodes a similarly sized C-terminal fragment of the protein. Interestingly, on further analysis of the alignment, three distinct amino acid sequence patterns emerge. The presence of the conserved functional GXXGXXK motif suggests that the protein domains encoded by steroid and phenol sulfotransferase 3'-terminal exons have evolved from a common ancestor. Furthermore, it is hypothesized that during the course of evolution, the 3'-terminal exon further diverged into at least three sulfotransferase subdivisions: a phenol or aryl group, an estrogen or phenolic steroid group, and a neutral steroid group.

Enhanced transglycosylation activity of Arthrobacter protophormiae endo-beta-N-acetylglucosaminidase in media containing organic solvents

The transglycosylation activity of endo-beta-N-acetylglucosaminidase from Arthrobacter protophormiae (endo-A) was enhanced by inclusion of organic solvents in the reaction mixture. In aqueous solution, the transglycosylation yield relative to starting substrate was 32% using Man9GlcNAc2Asn as donor and 0.5 M GlcNAc as acceptor. However, in the media containing 30% (v/v) acetone, dioxane, N,N-dimethylformamide, or dimethyl sulfoxide with 0.5 M GlcNAc as acceptor, the transglycosylation attained yields of 89, 13, 28, and 75%, respectively, as analyzed by high performance anion exchange chromatography. The enzyme was stable in media containing up to 30% acetone, 30% dimethyl sulfoxide, or 20% N,N-dimethylformamide at 37 degrees C for at least 30 min. The acceptor (GlcNAc) concentration must be greater than 0.2 M for efficient transglycosylation. Electrospray mass spectrometry analysis of the transglycosylation product obtained in 30% acetone with Man5GlcNAc2Asn as donor and methyl alpha-2-acetamido-2-deoxy-D-glucopyranoside as acceptor showed a mass ion of m/z 1249.4, consistent with the expected molecular weight. Analysis by 1H NMR of the product revealed that transglycosylation occurred at the C-4 of GlcNAc and the linkage was of the beta-configuration. In the acetone-containing medium, Glc, Man, 2-deoxy-Glc, and methyl alpha-D-GlcNAc can serve as a good acceptor as GlcNAc. Less favorable acceptors are xylose, fructose, 6-deoxy-Glc, and 3-O-methyl-D-glucose. On the other hand, GalNAc, Gal, allose, and 3-deoxy-Glc could not serve as acceptors of the enzyme transglycosylation.

Synthesis of neoglycoconjugates by transglycosylation with Arthrobacter protophormiae endo-beta-N-acetylglucosaminidase. Demonstration of a macro-cluster effect for mannose-binding proteins

The transglycosylation activity of endo-beta-N-acetylglucosaminidase from Arthrobacter protophormiae (endo-A) can be enhanced dramatically by inclusion of organic solvent in the reaction mixture (see accompanying article; Fan, J.-Q., Takegawa, K., Iwahara, S., Kondo, A., Kato, I., Abeygunawardana, C., and Lee, Y. C. (1995) J. Biol. Chem. 270, 17723-17729). This finding was extended to synthesis of important intermediates for preparation of neoglycoconjugates. When 0.2 M GlcNAc-O-(CH2)6NH2, GlcNAc-O-CH2CH = CH2, GlcNAc-O-(CH2)3-CH = CH2, GlcNAc-O-(CH2)3NHCOCH = CH2, GlcNAc-S-CH2CN, GlcNAc-S-(CH2)3CH3, or GlcNAc-S-CH2-CONHCH2CH(OMe)2 were used as acceptors in 30% acetone-containing media, the transglycosylation was accomplished with about 80% yield. The transglycosylation yields to benzyl beta-GlcNAc (67%), 4-methyl-umbelliferyl beta-GlcNAc (66%), p-nitrophenyl beta-GlcNAc (33%), and (GlcNAc-beta-S-CH2CH2CH2)2 (43%) were lower, because their poor solubilities allowed only 0.05 M or lower concentrations in the reaction mixture. A micromole-scale synthesis of Man9GlcNAc2-O-(CH2)3-NHCOCH = CH2 (Man9GlcNAc2-NAP) was accomplished with 90% yield, and the structure of the transglycosylation product was confirmed by 1H NMR. Man9GlcNAc2-NAP was co-polymerized with acrylamide. The ratio of sugar side chain to acrylamide in this glycopolymer was 1:44 and the molecular weight of glycopolymer was estimated to be between 1,500,000 and 2,000,000 by high performance gel filtration chromatography. The glycopolymer was shown to be a much more efficient inhibitor of binding by recombinant rat mannose binding protein-carbohydrate recognition domains (MBP-CRD) from serum (I50 = 3.5 microM Man9GlcNAc2-sugar chain) and liver (I50 = 74.5 nM) than soybean agglutinin.

The differences in structural specificity for recognition and binding between asialoglycoprotein receptors of liver and macrophages

The Gal/GalNAc-specific lectin on the surface of rat peritoneal macrophages (macrophage asialoglycoprotein binding protein, M-ASGP-BP), which consists of a single polypeptide chain of 42 kDa, can form a homo-oligomeric receptor exhibiting high affinity for asialoorosomucoid (ASOR) [Ozaki K., Ii M., Itoh N., Kawasaki T. (1992) J Biol Chem 267: 9229-35]. In this study, the binding affinity of M-ASGP-BP was studied by using a series of synthetic or natural glycosides as inhibitors of 125I-ASOR binding to recombinant M-ASGP-BP expressed on COS-1 cells (rM-ASGP-BP), and the results were compared with those of human hepatic lectin (HHL) on Hep G2 cells. Clustering of multiple Gal (or GalNAc) residues increased the binding affinity to M-ASGP-BP as well as to HHL. In contrast to HHL and other mammalian hepatic lectins, rM-ASGP-BP bound Gal residues tighter than GalNAc residues. A galactose-terminated triantennary N-glycoside, having one N-acetyl-lactosamine unit on the 6 branch and two N-acetyl-lactosamine units on the 3 branch of the trimannosyl core structure, showed affinity enhancement of approximately 10(5) over a monovalent ligand for HHL, while the same glycopeptide showed enhancement of about 2000-fold for rM-ASGP-BP. These results suggest that spatial arrangements of sugar combining sites and subunit organization of macrophage and hepatic lectins are different.

Donor substrate specificities of Gal beta 1,4GlcNAc alpha 2,6-sialyltransferase and Gal beta 1,3GalNAc alpha 2,3-sialyltransferase: comparison of N-acetyl and N-glycolylneuraminic acids

Using cloned sialyltransferases, Gal beta 1,3GalNAc alpha 2,3-sialyltransferase (ST3Gal I) and Gal beta 1,4GlcNAc alpha 2,6-sialyltransferase (ST6Gal I) from both chicken and mouse, CMP-NeuAc and CMP-NeuGc were compared as donor substrates with pyridylamino-oligo-saccharides as acceptors. ST6Gal I showed 4-7-times higher activity toward CMP-NeuGc than CMP-NeuAc, while for ST3Gal I there was no significant difference between them, irrespective of the origin of the enzymes. Also, the difference in donor substrate (i.e., NeuAc and NeuGc) had little effect on the preference to acceptor substrates of these enzymes. Thus, the results showed that the cloned sialyltransferases can utilize both CMP-NeuAc and CMP-NeuGc as donor substrates, and that the preference difference between the sialyltransferases to CMP-NeuGc and CMP-NeuAc could, at least partly, explain the discrepancy in the ratio of NeuAc and NeuGc in glycolipids and glycoproteins in individual tissues.

Three-Year Results of Photorefractive Keratectomy for Myopia

We evaluated the results of single-step photorefractive keratectomy (PRK) on 35 consecutive myopic eyes (19 patients) with follow up of 3 years or more. The range of preoperative myopia was from -2.00 diopters (D) to -6.00 D with astigmatism of less than 1.50 D. The excimer laser used in this study was the ExciMed UV 200LA, (Summit Technology), which was set to a maximum correction of -6.00 D at a 5.0-mm diameter ablation zone. Uncorrected visual acuity better than 20/25 was achieved in 82.9% of eyes. Spectacle corrected visual acuity was equal to or better than that of preoperative levels in 94.3%. The difference between attempted and achieved correction was within 1.00 D in 60.0% of eyes. The myopic regression curve was Y = 3.679-0.6876 log (X). If the regression remains constant, we expect that refraction at 5 years after PRK would be -1.48 D. Trace corneal haze was present in 12 eyes (34.3%). At three years the most common subjective complaint was mild decreased night vision with asthenopia. The findings suggest that myopic regression can occur as long as 3 years after PRK.

Photorefractive Keratectomy for Undercorrected Myopia After Radial Keratotomy: Two-Year Follow Up

We evaluated the clinical results of excimer laser photorefractive keratectomy (PRK) on 18 myopic eyes of 13 patients with residual myopia after radial keratotomy. Follow up was 24 months or more and the time interval between radial keratotomy and PRK ranged from 12 to 94 months. Patients were divided into two groups for analysis based on their preoperative myopia: group 1 (-6.00 diopters (D) or less), group 2 (more than -6.00 D). Uncorrected visual acuity at 2 years follow up was 20/40 or better in 86% (group 1) and 50% (group 2). Mean manifest refractive change was from -3.55 D to -0.91 D in group 1 and from -7.44 D to -2.50 D in group 2. Predictability within 1.00 D between attempted and achieved correction was 71.4% (group 1) and 80% (group 2). Most complications were transient except decreased spectacle corrected visual acuity in one eye--a complication also reported by others. Glare (61%) and decreased vision at night (50%) were the most troublesome subjective symptoms. These results show that previous radial keratotomy may not influence the myopic correction of PRK. Planned two-stage myopic correction (PRK after radial keratotomy) in high myopia can be considered a useful technique.

Glucocorticoid upregulates Na-K-ATPase alpha- and beta-mRNA via an indirect mechanism in proximal tubule cell primary cultures

Adrenalectomy leads to the decline in the levels of renal Na-K-adenosinetriphosphatase (Na-K-ATPase) alpha- and beta-subunit protein and mRNA. Both alpha- and beta-mRNA, however, return to the control level within 1 h after corticosterone administration. Whether or not glucocorticoid acts directly on a specific segment of nephron to upregulate Na-K-ATPase has not been determined. Studies were undertaken in an attempt to elucidate this problem. Using primary cultures of renal proximal tubules, we found that 24-h treatment with dexamethasone augmented Na-K-ATPase activity and induced coordinate increase of alpha- and beta-protein and mRNA abundance dependent on the doses in the range of 10(-8) to 10(-6) M. We further demonstrated that 24-h incubation of dexamethasone (10(-7) M) enhanced Na-K-ATPase activity by 58 +/- 14%, alpha- and beta-protein abundance by 70 +/- 18 and 51 +/- 10%, and alpha- and beta-mRNA levels by 87 +/- 12 and 62 +/- 11%, respectively. The time course studies revealed that significant increase of Na-K-ATPase activity and alpha and beta-protein abundance was reached within 4 hr of dexamethasone treatment. Pretreatment of cultured proximal tubule cells with cycloheximide (20 micrograms/ml) completely inhibited dexamethasone-induced increase of Na-K-ATPase alpha- and beta-mRNA. Our results indicate that dexamethasone upregulates Na-K-ATPase in proximal tubule cells via pretranslational mechanisms, which may be mediated by proteins.

Fine needle aspiration cytology of thymic carcinoid tumor

Carcinoid tumors of the thymus are very rare, and their cytologic findings have not been reported previously in English. Retrospective study of fine needle aspiration (FNA) cytologic features in four histopathologically verified thymic carcinoid tumors are described here in detail. The FNA cytology of thymic carcinoids is characterized by predominantly single and some loose clusters of small, round to oval cells with scanty cytoplasm, interspersed with some larger cells with moderate to abundant, granular cytoplasm. The differential diagnosis of the cytologic features between carcinoid tumor and other mediastinal tumors is also discussed.

Bioactivation of 5-hydroxymethyl-2-furaldehyde to an electrophilic and mutagenic allylic sulfuric acid ester

5-Hydroxymethyl-2-furaldehyde (HMF), a ubiquitous food contaminant, has been proposed to be metabolically activated through sulfonation of its allylic hydroxyl functional group. In support of this idea, we have found the strong direct mutagenicity of chemically synthesized sulfuric acid ester, 5-sulfooxymethylfurfural (SMF), in Salmonella typhimurium TA104. The intrinsic mutagenicity of this reactive ester was significantly inhibited by glutathione and glutathione S-transferase activity in dialyzed rat liver cytosol. The metabolic formation of SMF was elucidated by enhanced mutagenicity of HMF in the presence of rat hepatic cytosol enriched with the sulfo-group donor, 3'-phosphoadenosine-5'-phosphosulfate (PAPS). The PAPS- and cytosol-dependent mutagenicity of HMF was markedly lessened by sulfotransferase inhibitors such as 2,6-dichloro-4-nitrophenol and dehydroepiandrosterone. These results suggest that HMF can be metabolically activated to an allylic sulfuric acid ester which may play a role as an ultimate electrophilic metabolite in toxification of the parent compound in vivo.

Changes of white blood cells, immunosuppressive acidic protein, and interleukin-2 receptor after open heart surgery

There are a lot of immunological changes after major surgery, especially in open heart surgery when blood flows through a cardiopulmonary bypass system. We monitored leukocyte count, lymphocyte subpopulation count, soluble IL- 2 receptor (sIL-2r) and serum IL-2 levels, and an immunosuppressive acidic protein (IAP) level before and on the 1st, 7th, and 14th day after open heart surgery. It was noted that there were significant increases of total leukocyte and granulocyte counts for more than two weeks. But total lymphocyte, T-lymphocyte, b-lymphocyte, natural killer cell, suppressor T-cell, and helper T-cell all showed significant decreases in absolute numbers for more than one week as compared to the preoperative values. Serum IAP level was elevated for more than two weeks after operation. Serum IL-2 decreased but serum sIL-2R increased in the postoperative period. It is concluded that there is a period of immunosuppression after open heart surgery which lasts for at least one week and perhaps more than two weeks.

Congenital muscular dystrophy (non-Fukuyama type): a case report

A Taiwanese girl, aged 12 years, presented with early myogenic hypotonia, multiple joint contractures, mental subnormality and epilepsy. Computerized tomography scanning of the brain showed white matter hyperlucency. According to her clinical manifestations and radiological pictures, the patient could be the fourth oriental case who had the features of occidental-type cerebromuscular dystrophy.

The in vitro activity of beta-lactamase inhibitors in combination with cephalosporins against M. tuberculosis

Although there are reports that the addition of a beta-lactamase inhibitor to ampicillin or amoxicillin greatly improves their in vitro activity against M. tuberculosis, there are no written reports about the antituberculosis effects of beta-lactamase inhibitors in combination with cephalosporins against M. tuberculosis. In this report, we have determined the minimal inhibitory concentrations (MIC) of 5 cephalosporins with or without combination with beta-lactamase inhibitor against M. tuberculosis strains isolated from patients before antituberculosis treatment and checked the production of beta-lactamase by bacteria before this procedure. Four strains of M. tuberculosis were contaminated during the experiment, and all the other 16 strains hydrolyzed the nitrocefin disc, thus indicating a beta-lactamase producer. The MICs of cephalosporins alone against M. tuberculosis were 200-400 micrograms/ml for ceforanide, 100-400 micrograms/ml for cephapirin, 400-1600 micrograms/ml for cefamandole, 200-1600 micrograms/ml for cefotaxime, and 800-1600 micrograms/ml for ceftriaxone. After adding the equimolar concentrations of sulbactam, the MICs were reduced to 100-200 micrograms/ml for ceforanide, 12.5-100 micrograms/ml for cephapirin, 100-400 micrograms/ml for cefamandole, 25-200 micrograms/ml for cefotaxime, and 100-800 micrograms/ml for ceftriaxone. We concluded that sulbactam enhanced the antituberculosis effect of cephalosporins.

High affinity binding of the Entamoeba histolytica lectin to polyvalent N-acetylgalactosaminides

Entamoeba histolytica trophozoites initiate pathogenic colonization by adherence to host glycoconjugates via an amebic surface lectin which binds to galactose (Gal) and N-acetylgalactosamine (GalNAc) residues. Monovalent and multivalent carbohydrate ligands were screened for inhibition of E. histolytica lectin-mediated human red cell hemagglutination, revealing that: (i) the synthetic multivalent neoglycoprotein GalNAc39BSA (having an average of 39 GalNAc residues linked to bovine serum albumin) was 140,000-fold more potent an inhibitor than monovalent GalNAc and 500,000-fold more potent than monovalent Gal; and (ii) small synthetic multivalent ligands which bind with high affinity to the mammalian hepatic Gal/GalNAc lectin do not bind with high affinity to the E. histolytica lectin. Radioligand binding studies revealed saturable binding of 125I-GalNAc39BSA to E. histolytica membranes (KD = 10 +/- 3 nM, Bmax = 0.9 +/- 0.08 pmol/mg membrane protein). Maximal binding required the presence of calcium chloride (300 microM) or sodium chloride (50 mM), and had a broad pH maximum (pH 6-9). GalNAc39BSA was 200,000-fold more potent than monovalent GalNAc in blocking radio-ligand binding. Among synthetic saccharide-derivatized linear polymers, the GalNAc beta and GalNAc alpha 3Gal beta derivatives were the most potent, with GalNAc alpha and GalNAc alpha 3(Fuc alpha 2)Gal beta derivatives much weaker. The data support a model in which a unique pattern of spaced multiple GalNAc residues are the highest affinity targets for the E. histolytica lectin.

Determination of enantiomers of histidine, arginine and other amino acids by HPLC of their diastereomeric N-ethoxycarbonyldipeptides

Oxazolones and symmetrical anhydrides react efficiently with amino acids if the aqueous solvent includes a high proportion of dimethylformamide, the temperature is not lowered and sodium carbonate is used for neutralizing the amino acids. Subsequent separation of the diastereomeric products by high-performance liquid chromatography on a C-18 column provides a simple method for determining enantiomers. The symmetrical anhydrides of N-ethoxycarbonylvaline and phenyl-alanine are reagents suitable for determining enantiomers. Enantiomers of arginine and histidine in a mixture of amino acids can be determined if the products of the reaction are first fractionated by a simple extraction.

Surgical treatment of second primary lung cancer: report of eight cases

Of 312 patients undergoing resection for lung cancer at National Taiwan University Hospital during 1980 to 1990, eight presented with second primary lung cancer. One patient had synchronous and seven patients had metachronous primaries. There were five males and three females with ages ranging from 41 to 77 years. In the metachronous group, two patients had a different histology between the first and the second tumor, and the intervals between the two tumors varied from 12 to 60 months. The initial resections included pneumonectomy in one and lobectomy in six patients. At the second operation, the surgical procedures included lobectomy in three, completed pneumonectomy in one, segmentectomy in another, and wedge resection in two patients. There was no operative mortality and all patients were regularly followed up from 6 months to 6 years after the second operation. Two patients died, one from repeated respiratory tract infection and the other from brain metastasis. Kaplan-Meier analysis showed 2-year and 3-year survivals of 80% and 60%, respectively. It can be concluded that surgical resection for second primary lung cancer is justified, as it can prolong the patient's survival. Lobectomy can be performed for patients with a second primary lung cancer and sufficient lung reserve, but limited resection should be chosen for patients with poor lung reserve.

Enzymatic activity of a developmentally regulated member of the sialyltransferase family (STX): evidence for alpha 2,8-sialyltransferase activity toward N-linked oligosaccharides

We have detected sialyltransferase activity of recombinant mouse STX, which was cloned from rat brain as a new member of the sialyltransferase family, but sialyltransferase activity of which had not been detected previously [Livingston and Paulson, J. Biol. Chem. (1993) 268, 11504-11507]. The activity of mouse STX was specific toward sialylated glycoproteins. N-Glycanase treatment and linkage-specific sialidase treatment of glycoproteins revealed that STX transfers sialic acids through alpha 2,8-linkages to only N-linked oligosaccharides of glycoproteins. However, polymerase activity for polysialic acid synthesis was not detected for this sialyltransferase. Since this alpha 2,8-sialyltransferase gene is highly restricted in fetal and newborn brain, it may be involved in the polysialylation of glycoproteins, especially of N-CAM.

Adrenocortical pregnenolone binding activity resides with estrogen sulfotransferase

Cytosol prepared from Chinese hamster ovary (CHO)-K1 cells transfected with guinea pig estrogen sulfotransferase (EST) cDNA demonstrated high affinity binding activity for pregnenolone as well as 17 beta-estradiol but failed to bind dehydroepiandrosterone or testosterone. In contrast, cytosol prepared from nontransfected CHO-K1 cells did not demonstrate steroid binding activity. Additionally, the binding activity for pregnenolone and 17 beta-estradiol was dependent on the presence of the cofactor adenosine-3',5'-diphosphate. Pregnenolone and 17 beta-estradiol effectively competed with each other for binding. On the other hand, pregnenolone, which was not sulfonated, did not inhibit the sulfonation of 17 beta-estradiol by expressed EST.

Integrity of intermediate filaments is associated with the development of acquired thermotolerance in 9L rat brain tumor cells

Withangulatin A (WA), a newly discovered withanolide isolated from an antitumor Chinese herb, has been shown to be a vimentin intermediate filament-targeting drug by using immunofluorescence microscopy. Together with cytochalasin D and colchicine, these drugs were employed to investigate the importance of vimentin intermediate filaments, actin filaments, and microtubules in the development of acquired thermotolerance in 9L rat brain tumor cells treated at 45 degrees C for 15 min (priming heat-shock). Acquired thermotolerance was abrogated in cells incubated with WA before the priming heat-shock but it could be detected in cells treated with WA after the priming heat-shock. In contrast, cytochalasin D and colchicine do not interfere with the development of thermotolerance at all. The intracellular localizations of vimentin and the constitutive heat-shock protein70 (HSC70) in treated cells were examined by using immunofluorescence microscopy and detergent-extractability studies. In cells treated with WA before the priming heat-shock, vimentin IFs were tightly aggregated around the nucleus and unable to return to their normal organization after a recovery under normal growing conditions. In contrast, the IF network in cells treated with WA after the priming heat-shock was able to reorganize into filamentous form after a recovery period, a behavior similar to that of the cells treated with heat-shock only. HSC70 was found to be co-localized with vimentin during these changes. It is suggested that the integrity of intermediate filaments is important for the development of thermotolerance and that HSC70 may be involved in this process by stabilizing the intermediate filaments through direct or indirect binding.

Obstruction after self-expanding metallic stents in tuberculous bronchial stenosis

Expandable metallic stents seemed to be a good method in tuberculous bronchial stenosis that does not respond to medical therapy. But there was no long-term follow-up study after stents insertion in tuberculous bronchial stenosis. We report a case of obstruction after successful Gianturco metallic stents insertion due to tuberculous bronchial stenosis.

Structural and functional characterization of estrogen sulfotransferase isoforms: distinct catalytic and high affinity binding activities

Estrogen sulfotransferase (EST) purified from the guinea pig (gp) adrenal gland consists of multiple charge isoforms with isoelectric points (pls) ranging from 6.5 to 5.2. Four individual isoforms were isolated for use in antibody production, as well as for tryptic fragmentation analysis. The multiple charge isoforms manifested a high degree of relatedness as evidence by complete immunocross-reactivity. This relatedness was further demonstrated by peptide mapping analysis, which revealed essentially identical elution profiles for three of the isoforms, whereas the fourth most acidic isoform, although similar to the other three isoforms, demonstrated some differences. To further explore the nature of the charge isoforms, native gpEST and EST expressed by CHO-K1 cells transfected with the gpEST cDNA were subjected to additional biochemical characterization. An interesting finding was that, in addition to EST activity, gpEST bound estradiol with a high affinity [dissociation constant (Kd) 10 nM]; furthermore, the binding activity was absolutely dependent on the cofactor, adenosine-3',5'-diphosphate (3',5'-ADP). An unexpected and novel finding was that only the most basic pl 6.5 isoform was catalytically active, while estradiol-binding activity was associated with a more acidic isoform (pl 5.5-5.2); however, it has not as yet been possible to definitively assign the binding activity to a specific isoform.(ABSTRACT TRUNCATED AT 250 WORDS)

Exon 8 mutation of p53 gene associated with nodal metastasis in non-small-cell lung cancer

The epidemiologic characteristics of lung cancer in Taiwan differ from those in other parts of the world in low male-to-female ratio, the high percentage of adenocarcinoma, and the relatively high percentage of nonsmokers who are victims. To investigate possible correlation between p53 gene alteration and the unique characteristics of lung cancer here, p53 gene status of 36 patients with primary, resected non-small-cell lung cancer (NSCLC) was studied by directly sequencing the cDNA of the p53 gene, then acquiring clinical and pathologic data to correlate p53 gene status with clinical parameters and pathologic staging. Missense mutations were present in 42% (15 of 36) of patients with NSCLC, including 42% (10 of 24) with adenocarcinomas, and 45% (five of 11) with squamous cell carcinomas. The frequency of p53 mutation was 50% in smokers and 29% in nonsmokers (p = 0.355). The mutation occurred most frequently in exon 8 (56%), and G:C to A:T transitions in non-CpG or CpG sites were the most commonly observed base changes (56%). These findings differ from the high prevalence of G to T transversion found in previous reports. The frequency of metastasis in hilar and mediastinal lymph nodes was significantly higher in tumors with p53 mutations. The association with nodal stage was strong for mutations within exon 8, but it was less apparent for mutations in other exons probably because of the small number. This study suggests that p53 gene missense is common in NSCLC in Taiwan, but smoking is probably not the sole contributing factor. More interestingly, p53 gene mutations, especially those in exon 8, may be associated with regional nodal metastasis.