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Biomedical subjects

S Shin

Publications and source records attributed to S Shin.

At least 91 records · Page 5Linked to original sources
PubMed1998

Clinical appearances, healing patterns, risk factors, and outcomes of horses with fungal keratitis: 53 cases (1978-1996)

OBJECTIVE: To compare initial clinical appearances, healing mechanisms, risk factors, and outcomes of horses with fungal keratitis. DESIGN: Retrospective analysis. ANIMALS: 52 horses (53 eyes) with fungal keratitis. PROCEDURE: Medical records and clinical photographs of eyes were reviewed. Keratomycoses were categorized on the basis of clinical appearance at initial examination and pattern of healing. RESULTS: Five distinct forms of mycotic keratitis were recognized. Of 53 affected eyes, 34 (64%) retained sight and had varying degrees of corneal scarring after treatment, 6 (11%) had a cosmetic appearance but were blind, and 13 (25%) were enucleated. Bacterial-like ulcers were the most frequent type and the most difficult for predicting outcome. Eyes affected by superficial fungal keratitis were likely to be chronically infected and to require debridement and extended treatment but usually healed with minimal scarring. Keratomycosis with a surrounding furrow resulted in a grave prognosis. Aspergillus organisms were isolated from 9 of 10 such eyes. Cake-frosting material was a positive prognostic sign. Fungal corneal stromal abscesses tended to be caused by yeast. CLINICAL IMPLICATIONS: This information will aid practitioners in recognizing various forms of fungal keratitis and guide them when making therapeutic decisions and prognoses for affected horses.

Abscess↗
PubMed1998

Mn Lalpha,beta and F Kalpha resonant X-ray fluorescence spectroscopy of MnF(2).

Mn Lalpha,beta and F Kalpha(1,2) (K-L(3,2)) X-ray fluorescence spectra of MnF(2) were measured when the excitation X-ray energy was higher and lower than the threshold energies. Monochromated synchrotron radiation was used for primary excitation. The resonance fluorescence of Mn Lbeta and the multiply ionized F Kalpha(3,4) satellites (KL-L(2)) were observed.

Journal Article↗
PubMed1998

Spectrometer for polarized soft X-ray Raman scattering.

An experimental system for polarized soft X-ray Raman scattering spectroscopy has been constructed. The soft X-ray spectrometer is based on the Rowland circle geometry with a holographic spherical grating. Three types of gratings are used to cover the energy range from 18 eV to 1200 eV. According to a ray-trace simulation, the resolution is expected to be 200 meV at 700 eV by using a 10 micro m slit width. The polarized and depolarized soft X-ray Raman scattering spectra can be measured by rotating the soft X-ray spectrometer around the axis of the incident beam. Preliminary measurements of polarized and depolarized spectra were accomplished at undulator beamline BL-2C of the Photon Factory.

Journal Article↗
PubMed1998

Apoptosis as a mechanism of 2-chloroethylethyl sulfide-induced cytotoxicity.

Apoptosis is a mode of active cell death. We have examined whether 2-chloroethylethyl sulfide (CEES), a sulfur vesicating agent, triggers apoptosis as a cytotoxic mechanism. Incubation of thymocytes with CEES, resulted in an induction of apoptotic features of cell death. Treatment of cells with 100 microM CEES for 5 h increased DNA fragmentation to approximately 40% of control. The fragmentation of DNA was visualized by agarose gel electrophoresis. It showed ladder pattern of DNA fragmentation, which indicates internucleosomal cleavage of DNA. Further evidence of apoptosis was observed in morphological changes of nuclei by using the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) method. The percentage of TUNEL positive cells was dependent upon CEES concentrations. CEES induced the classical morphological features of apoptosis in nucleus. These features were accompanied by condensation of chromatin, which arranged in sharply declined clumps and fragmentation of nucleus. To study requirement for synthesis of new protein in CEES-induced apoptosis, we studied the effect of cycloheximide for apoptotic activity. This protein synthesis inhibitor did not suppress the CEES-induced apoptotic activity. Taken together, these results suggest that CEES-induced apoptosis as a cytotoxicmechanism and this process occurs independent of synthesis of new protein.

Animals↗
PubMed1998

Substrate binding and sequence preference of the proteasome revealed by active-site-directed affinity probes.

BACKGROUND: The proteasome is a multicatalytic protease complex responsible for most cytosolic protein breakdown. The complex has several distinct proteolytic activities that are defined by the preference of each for the carboxyterminal (P1) amino acid residue. Although mutational studies in yeast have begun to define substrate specificities of individual catalytically active beta subunits, little is known about the principles that govern substrate hydrolysis by the proteasome. RESULTS: A series of tripeptide and tetrapeptide vinyl sulfones were used to study substrate binding and specificity of the proteasome. Removal of the aromatic amino-terminal cap of the potent tripeptide vinyl sulfone proteasome inhibitor 4-hydroxy-3-iodo-2-nitrophenyl-leucinyl-leucinyl-leucine vinyl sulfone resulted in the complete loss of binding and inhibition. Addition of a fourth amino acid (P4) to the tri-leucine core sequence fully restored inhibitory potency. 125I-labeled peptide vinyl sulfones were also used to examine inhibitor binding and to determine the correlation of subunit modification with inhibition of peptidase activity. Changing the amino acid in the P4 position resulted in dramatically different profiles of beta-subunit modification. CONCLUSIONS: The P4 position, distal to the site of hydrolysis, is important in defining substrate processing by the proteasome. We observed direct correlations between subunit modification and inhibition of distinct proteolytic activities, allowing the assignment of activities to individual beta subunits. The ability of tetrapeptides, but not tripeptide vinyl sulfones, to act as substrates for the proteasome suggests there could be a minimal length requirement for hydrolysis by the proteasome. These studies indicate that it is possible to generate inhibitors that are largely specific for individual beta subunits of the proteasome by modulation of the P4 and carboxy-terminal vinyl sulfone moieties.

Amino Acid Sequence↗
PubMed1998

Effects of the neurotoxin 3-acetylpyridine on levels of soluble proteins and enzyme activities in various tissues of Japanese quail.

(1) The effects of the neurotoxin 3-acetylpyridine on the levels of soluble proteins and enzyme activities in various tissues of Japanese quail were investigated. (2) SDS-polyacrylamide gel electrophoresis showed that in the brain the soluble proteins with a molecular mass corresponding to 18 kDa were increased in quail treated with this toxin. The soluble liver proteins with the largest molecular masses (200, 120, 98, 80.5 and 58 kDa) were either missing or present at lower concentrations in the treated group compared to those in the controls while those of lower molecular mass (62, 55, 45, 36.5 and 24 kDa) were found to be present in higher concentrations. Similarly, treatment with 3-acetylpyridine tended to decrease the concentration of soluble proteins in pectoral muscle having a high molecular mass (160, 98, 60, 33, 30.5, 22 and 14 kDa) and to increase those having a low molecular mass (26, 20, 19.5 and 16 kDa). (3) There was a marked reduction in the treatment group in the concentration of NAD in pectoral muscle but not in other tissues. A similar observation was also made with total RNAs levels. (4) The specific activity of malic enzyme and glyceraldehyde-3-phosphate dehydrogenase was markedly reduced in the liver and pectoral muscle of the treatment group but was not affected in other tissues. The specific activity of 6-phosphogluconate dehydrogenase was significantly lower in the liver only, and that of lactic dehydrogenase and acetylcholinesterase was not affected in any of the tissues examined. (5) The results suggest that the metabolic actions of 3-acetylpyridine are quite distinct from those shown by niacin deficiency and its analog such as 6-aminonicotinamide.

Animals↗
PubMed1998

A randomized, prospective, comparative study of manual and automated renal biopsies.

A percutaneous renal biopsy can be performed in several ways, including using a spring-loaded biopsy gun. As this form of renal biopsy has become more popular, a controversy has developed regarding tissue adequacy and the incidence of complications. To compare these two aspects in an automated biopsy and a manual biopsy, we studied 166 patients assigned to one of the two renal biopsy methods. In a randomized, prospective manner from June 1994 until February 1997, group 1 (67 patients) received a 14 G Tru-cut needle (Baxter, Deerfield, IL) manual biopsy while group 2 (99 patients) received an 18 G automated gun biopsy. There was no difference in sex, age, hemoglobin level, prothrombin time, partial thromboplastin time, or diastolic and systolic blood pressure prebiopsy in groups I and II. Indications for biopsy were proteinuria (38%), proteinuria accompanied by hematuria (31.3%), acute renal failure (9.6%), lupus nephropathy (9.6%), chronic renal failure (6%), and hematuria only (5.4%). In group I, the number of cores was 1.88 +/- 0.56, the glomeruli obtained were 27.3 +/- 13.8, and the number of glomeruli per core were 15.3 +/- 8.4. In group II, the values were 2.37 +/- 0.88, 20.7 +/- 11.1, and 9.95 +/- 6.9, respectively. These results showed a statistically significant difference (P < 0.05). In all cases, pathological diagnosis was possible. The histology showed IgA nephropathy in 25.9%, minimal change disease in 16.3%, lupus nephritis in 11.4%, membranous glomerulonephropathy in 9.3%, membranoproliferative glomerulonephritis in 5.4%, and others. The incidence of postbiopsy hematoma was marginally greater in group I (22.3% v 11.1%) and the area of perirenal hematoma shown on ultrasound 24 hours postbiopsy was larger in group I, as well (848 +/- 623 mm2 v 338 +/- 260 mm2). Hematocrit levels before and after biopsy showed a significant difference (34.9% +/- 7.9% and 34.0% +/- 7.6%, respectively; P < 0.05) in group I, but no significant difference was observed in group II (35.1% +/- 7.0% and 34.7% +/- 6.9%). Both techniques rendered adequate tissue sampling, but the extent of bleeding was more severe with the manual 14 G Tru-cut needle biopsy.

Acute Kidney Injury↗
PubMed1998

Genotyping HIV-1 and HCV strains by a combinatorial DNA melting assay (COMA).

BACKGROUND: Human immunodeficiency virus type 1 (HIV-1) and hepatitis C virus (HCV) strains can be genetically classified into genetic lineages known as genetic types or subtypes according to phylogenetic analyses of complete or partial nucleotide sequences of their genomes. The genetic classification of HIV-1 and HCV strains has important implications for the development of globally effective vaccines and for the management of patients. MATERIALS AND METHODS: A new method, termed combinatorial DNA melting assay (COMA), allows rapid accessing of comparative genetic information between related DNA sequences, making it possible to rapidly and accurately genotype unknown HIV-1 and HCV strains. COMA is mainly based on the differential melting properties of long DNA heteroduplexes. Combinatorial arrays of DNA heteroduplexes are formed when captured PCR-amplified reference DNA with known nucleotide sequences are combined with solution-phase complementary and antigenically labeled DNA with unknown sequences. Genetic divergence between the known and the unknown sequences is inferred as the experimentally derived melting curves of the two strands of the DNA heteroduplexes increasingly diverge. RESULTS: COMA was successfully applied to the genetic classification of HIV-1 and HCV strains into phylogenetic lineages or subtypes. CONCLUSIONS: Use of this assay should accelerate current efforts to understand the global molecular epidemiology of HIV-1 and HCV and may extend to the genetic characterization of other genetically diverse infectious pathogens associated with numerous diseases.

Base Composition↗
PubMed1997

Relaxation process of the excited state and selection rule in the soft X-ray emission of Si and cBN.

The soft X-ray emission spectra of Si and cubic boron nitride (cBN) are compared in the Si2p- and B1s-core exciton regions because inversion symmetry is lost and the band gap is extremely large for cBN although both crystal structures are very similar. The background in the soft X-ray emission spectrum of Si is much larger than that for cBN but becomes extremely weak as the excitation energy becomes low and the Raman process becomes dominant compared with the fluorescence process. The background is found to be mainly formed by electron excitation from the valence band to the conduction band. The Raman spectrum is similar to the absorption spectrum in cBN, while those of Si are quite different from each other. It is shown that the centrosymmetry is important in the selection rule of Raman scattering. In resonant Raman scattering the selection rule partly breaks down due to the lattice relaxation process that emits an ungerade phonon in the intermediate state.

Journal Article↗
PubMed1997

Involvement of iclR and rpoS in the induction of acs, the gene for acetyl coenzyme A synthetase of Escherichia coli K-12.

Two independent pathways in Escherichia coli convert acetate to acetyl CoA: reversal of acetate production by phosphotransacetylase and acetate kinase, and the acetyl-CoA synthetase (Acs) pathway that scavenges acetate. We investigated acs gene expression by using a cat transcriptional fusion. It was observed that acs expression varies depending on the carbon sources used and occurs in the stationary phase of growth even in the absence of acetate. Mutations in iclR for the repressor of the glyoxylate shunt and in rpoS for the stationary phase sigma factor reduced the consumption of acetate mediated by Acs, indicating that both are involved in acs regulation.

Acetate-CoA Ligase↗
PubMed1997

Epithelial cell polarity affects susceptibility to Pseudomonas aeruginosa invasion and cytotoxicity.

Intact tissues are relatively resistant to Pseudomonas aeruginosa-induced disease, and injury predisposes tissue to infection. Intact epithelia contain polarized cells that have distinct apical and basolateral membranes with unique lipids and proteins. In this study, the role of cell polarity in epithelial cell susceptibility to P. aeruginosa virulence mechanisms was tested. Madin-Darby canine kidney (MDCK) cells, human corneal epithelial cells, and primary cultures of two different types of airway epithelial cells were grown on Transwell filters or in plastic tissue culture wells. P. aeruginosa invasion of cells was quantified by gentamicin survival assays with two isolates that invade epithelial cells (6294 and PAO1). Cytotoxic activity was assessed by trypan blue exclusion assays with two cytotoxic strains (6206 and PA103). Basolateral surfaces of cells were exposed by one of two methods: EGTA pretreatment of epithelial cells or growth of cells in low-calcium medium. Both methods of exposing basolateral membranes increased epithelial cell susceptibility to P. aeruginosa invasion and cytotoxicity. Migrating cells were also found to be more susceptible to P. aeruginosa invasion than confluent monolayers that had established membrane polarity. Monolayers of MDCK cells that had been selected for resistance to killing by concanavalin A were resistant to both cytotoxicity and invasion by P. aeruginosa because they were more efficiently polarized for their susceptibility to P. aeruginosa virulence factors than regular MDCK cells and not because they were defective in glycosylation. These results suggest that there are factors on the basolateral surfaces of epithelial cells that promote interaction with P. aeruginosa or that there are inhibitory factors on the apical cell surface. Thus, cell polarity of intact epithelia is likely to contribute to defense against P. aeruginosa infection.

Animals↗
PubMed1997

Isolation and mapping of karyopherin alpha 3 (KPNA3), a human gene that is highly homologous to genes encoding Xenopus importin, yeast SRP1 and human RCH1.

From a human fetal-brain cDNA library, we isolated and characterized a novel gene (KPNA3) encoding a protein highly homologous to certain nuclear transport proteins of Xenopus and human. The complete cDNA clone, designated karyopherin alpha 3, contained an open reading frame of 1,563 nucleotides encoding 521 amino acids. The predicted amino acid sequence showed 48%, 45% and 48% identity with Xenopus importin, yeast SRP1 and human RCH1, respectively. The similarities among these proteins suggest that karyopherin alpha 3 may be involved in the nuclear transport system. Eight repeats of the arm motif were well conserved among these proteins. The N-terminal region of the predicted karyopherin alpha 3 product was highly basic and the C-terminal region was strongly acidic. A 4.3-kb transcript was expressed in all adult human tissues examined by Northern blotting. The cDNA clone was assigned to chromosome band 13q14.3 by fluorescence in situ hybridization.

Amino Acid Sequence↗
PubMed1996

Effects of calmodulin antagonists and anesthetics on the skin lesions induced by 2-chloroethylethyl sulfide.

The effects of calmodulin antagonists and anesthetics on the skin lesions induced by an alkylating vesicant, 2-chloroethylethyl sulfide, were investigated using female hairless mice. 2-Chloroethylethyl sulfide, topically applied (0.6 microliter/5 mm in diameter) on the back skin of hairless mice, induced mild to moderate petechiae on the 1st day, and ulcers with a thick scab after 3 days. The healing process started after 6 days, resulting in shedding of scabs on 9.52 days. Water-soluble ointment bases showed some beneficial effects, whereas oily bases made the skin lesions worse. Trifluoperazine (0.5-1%) and thioridazine (2%), potent calmodulin antagonists, in Pluronic F-127 base substantially prevented the development of 2-chloroethylethyl sulfide-induced skin lesions. A similar effect was achieved with pentamidine (10%), another type of calmodulin antagonist, but not with ketoconazole, a weak calmodulin antagonist. In addition, anesthetics, such as lidocaine and pentobarbital, showed some protection, although at high concentrations (> 5%). As judged by the microscopic appearance, trifluoperazine successfully reduced the hemorrhage and the infiltration of inflammatory cells in early skin lesions, and the formation of thick scabs, which leads to granulomatous scar tissue in late lesions. These results suggest that some calmodulin antagonists and anesthetics in water-soluble bases might be a choice for the treatment of 2-chloroethylethyl sulfide-induced skin burns.

Adjuvants, Anesthesia↗