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Biomedical subjects

E Kim

Publications and source records attributed to E Kim.

At least 217 records · Page 12Linked to original sources
PubMed1996

Ampicillin-sulbactam is effective in prevention and therapy of experimental endocarditis caused by beta-lactamase-producing coagulase-negative staphylococci.

Optimal strategies for the prophylaxis and therapy of endocarditis caused by oxacillin-resistant, coagulase-negative staphylococci in patients with native or prosthetic valvular heart disease are not well defined. We compared the in vivo efficacies of ampicillin-sulbactam-based regimens with those of vancomycin-based oxacillin-resistant, beta-lactamase-producing coagulase-negative staphylococcal isolate (Staphylococcus haemolyticus SE220). Ampicillin-sulbactam (100 and 20 mg/kg of body weight, respectively, given intramuscularly in a two-dose regimen) was equivalent to vancomycin (30 mg/kg given intravenously in a two-dose regimen) in its prophylactic efficacy against the coagulase-negative staphylococcal strain (93 and 80%, respectively). The combination of ampicillin-sulbactam plus either rifampin or vancomycin did not enhance the prophylactic efficacy compared with that of ampicillin-sulbactam or vancomycin alone. In the therapy of established aortic valve endocarditis in rabbits caused by this same coagulase-negative staphylococcal strain, animals received 7-day ampicillin-sulbactam-based or vancomycin-based regimens with or without rifampin. All treatment regimens were effective at lowering intravegetation coagulase-negative staphylococcal densities and rendering vegetations culture negative compared with the coagulase-negative staphylococcal densities and vegetations of untreated controls, with ampicillin-sulbactam in combination with rifampin or vancomycin being the most active regimen. However, only the regimen of ampicillin-sulbactam in combination with vancomycin effectively prevented relapse of endocarditis posttherapy after a 5-day antibiotic-free period. For animals receiving rifampin-containing regimens, relapses of endocarditis were associated with the in vivo development of rifampin resistance among coagulase-negative staphylococcal isolates in the vegetation. Ampicillin-sulbactam was highly effective in the prevention of experimental endocarditis caused by a beta-lactamase-producing, oxacillin-resistant coagulase-negative staphylococcal strain. Ampicillin-sulbactam was also efficacious for the therapy of coagulase-negative staphylococcal endocarditis, especially when it was combined with vancomycin to prevent posttherapeutic relapses.

Ampicillin↗
PubMed1996

Comparison of fluconazole and amphotericin B in prophylaxis of experimental Candida endocarditis caused by non-C. albicans strains.

Amphotericin B (1 mg/kg of body weight, intravenous) and fluconazole (100 mg/kg, intraperitoneal) were compared in the prophylaxis of experimental Candida endocarditis caused by drug-susceptible, non-C. albicans strains C. tropicalis and C. parapsilosis. Neither antifungal agent was effective at preventing endocarditis due to either Candida strain when either agent was administered in a single-dose regimen (1 h prior to fungal challenge); the prophylactic efficacy of both agents increased substantially when a second prophylactic dose was given (24 h postchallenge). The excellent prophylactic efficacy of fluconazole, a fungistatic agent, underscores the importance of microbistatic mechanisms in endocarditis prophylaxis.

Amphotericin B↗
PubMed1996

Genetic structures of the genes encoding 2,3-dihydroxybiphenyl 1,2-dioxygenase and 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acid hydrolase from biphenyl- and 4-chlorobiphenyl-degrading Pseudomonas sp. strain DJ-12.

The pcbC and pcbD genes of Pseudomonas sp. strain DJ-12, a natural isolate degrading biphenyl and 4-chlorobiphenyl, encode the 2,3-dihydroxybiphenyl 1,2-dioxygenase and 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acid hydrolase, respectively. The two genes were sequenced and appear to be present in the order pcbD-pcbC as an operon.

Base Sequence↗
PubMed1996

Homology between genes for aromatic hydrocarbon degradation in surface and deep-subsurface Sphingomonas strains.

The cloned genes for aromatic hydrocarbon degradation from Sphingomonas yanoikuyae B1 were utilized in Southern hybridization experiments with Sphingomonas strains from the surface and deep-subsurface environments. One hybridization pattern was obtained with BamHI-digested genomic DNAs for two surface strains, while a differing pattern was seen for five deep-subsurface strains. The cross-hybridizing genes were located in the chromosomes of the surface strains and on plasmids in the deep-subsurface strains.

Bacteria↗
PubMed1996

Fluorescent in situ hybridization assessment of chromosome copy number in buccal mucosal cells.

Sex chromatin (Barr body) analysis of buccal mucosal cells has been recognized for many years as an inexpensive, noninvasive and rapid means of sex determination. The conventional Barr body analysis using Papanicolaou stain was discontinued as a routine test because of its lack of reliability and its inability to detect mosaicism and other chromosomal abnormalities. With the advent of recombinant DNA technology and the availability of molecular probes, however, the value of this simple albeit obsolete test should be re-evaluated. The results of the authors' experience in optimizing a fluorescent in situ hybridization (FISH) assay on buccal mucosal cells are described. The utility and potential of this assay are explored and discussed.

Evaluation Studies as Topic↗
PubMed1995

Clustering of Shaker-type K+ channels by interaction with a family of membrane-associated guanylate kinases.

ANCHORING of ion channels at specific subcellular sites is critical for neuronal signalling, but the mechanisms underlying channel localization and clustering are largely unknown (reviewed in ref. 1). Voltage-gated K+ channels are concentrated in various neuronal domains, including presynaptic terminals, nodes of Ranvier and dendrites, where they regulate local membrane excitability. Here we present functional and biochemical evidence that cell-surface clustering of Shaker-subfamily K+ channels is mediated by the PSD-95 family of membrane-associated putative guanylate kinases, as a result of direct binding of the carboxy-terminal cytoplasmic tails to the K+ channel subunits to two PDZ (also known as GLGF or DHR) domains in the PSD-95 protein. The ability of PDZ domains to function as independent modules for protein-protein interaction, and their presence in other junction-associated molecules (such as ZO-1 (ref. 3) and syntrophin), suggest that PDZ-domain-containing polypeptides may be widely involved in the organization of proteins at sites of membrane specialization.

Adaptor Proteins, Signal Transducing↗
PubMed1995

Purification of cranin, a laminin binding membrane protein. Identity with dystroglycan and reassessment of its carbohydrate moieties.

Cranin was described in 1987 as a membrane glycoprotein expressed in brain and many other tissues, which binds laminin with high affinity in a calcium-dependent manner. Dystrophin-associated glycoprotein ("dystroglycan") is a laminin-binding protein cloned in 1992 whose relation to cranin has remained uncertain. Here we describe the purification of cranin to homogeneity from sheep brain, show cranin to be a form of dystroglycan, and localize the N terminus of beta-dystroglycan to amino acid residue 654. We find that brain alpha-dystroglycan is tightly associated with membranes, and localizes to regions of synaptic contact as assessed by immunocytochemistry of rat cerebellum. Brain alpha-dystroglycan expresses high mannose/hybrid N-linked saccharides, terminal GalNAc residues, and the HNK-1 epitope. Although dystroglycan has previously been presumed to be a proteoglycan, the amino acid sequence, pI, O-sialoglycoprotease susceptibility, lectin-binding profile, and laminin-binding properties of brain dystroglycan are more typical of mucin-like proteins. Furthermore, using CHO mutant cell lines deficient in xylosyltransferase and galactosyltransferase I, which are required for glycosaminoglycan biosynthesis, it is shown that chondroitin sulfate and heparan sulfate are not critical for laminin binding, and indeed are apparently not expressed at all in dystroglycan from CHO cells.

Amino Acid Sequence↗
PubMed1995

The benzene metabolite p-benzoquinone forms adducts with DNA bases that are excised by a repair activity from human cells that differs from an ethenoadenine glycosylase.

Benzene is a ubitiquous human environment mental carcinogen. One of the major metabolites is hydroquinone, which is oxidized in vivo to give p-benzoquinone (p-BQ). Both metabolites are toxic to human cells. p-BQ reacts with DNA to form benzetheno adducts with deoxycytidine, deoxyadenosine, and deoxyguanosine. In this study we have synthesized the exocyclic compounds 3-hydroxy-3-N4-benzetheno-2'-deoxycytidine (p-BQ-dCyd) and 9-hydroxy-1,N6-benzetheno-2'-deoxyadenosine (p-BQ-dAdo), respectively, by reacting deoxycytidine and deoxyadenosine with p-BQ. These were converted to the phosphoamidites, which were then used to prepare site-specific oligonucleotides with either the p-BQ-dCyd or p-BQ-dAdo adduct (pbqC or pbqA in sequences) at two different defined positions. These oligonucleotides were efficiently nicked 5' to the adduct by partially purified HeLa cell extracts--the pbqC-containing oligomer more rapidly than the pbqA-containing oligomer. In contrast to the enzyme binding to derivatives produced by the vinyl chloride metabolite chloroacetaldehyde, the oligonucleotides up to 60-mer containing p-BQ adducts did not bind measurably to the same enzyme preparation in a gel retardation assay. Furthermore, there was no competition for the binding observed between oligonucleotides containing 1,N6-etheno A deoxyadenosine (1,N6-etheno-dAdo; epsilon A in sequences) and these oligomers containing either of the p-BQ adducts, even at 120-fold excess. When highly purified fast protein liquid chromatography (FPLC) enzyme fractions were obtained, there appeared to be two closely eluting nicking activities. One of these enzymes bound and cleaved the epsilon A-containing deoxyoligonucleotide. The other enzyme cleaved the pbqA- and pbqC-containing deoxyoligonucleotides. One additional unexpected fact was that bulk p-BQ-treated salmon sperm DNA did compete effectively with the epsilon A-containing oligonucleotide for protein binding. This raises the possibility that such DNA contains other, as-yet-uncharacterized adducts that are recognized by the same enzyme that recognizes the etheno adducts. In summary, we describe a previously undescribed human DNA repair activity, possibly a glycosylase, that excises from DNA pbqC and pbqA, exocyclic adducts resulting from reaction of deoxycytidine and deoxyadenosine with the benzene metabolite, p-BQ. This glycosylase activity is not identical to the one previously reported from this laboratory as excising the four etheno bases from DNA.

Autoradiography↗
PubMed1995

RIP: a novel protein containing a death domain that interacts with Fas/APO-1 (CD95) in yeast and causes cell death.

Ligation of the extracellular domain of the cell surface receptor Fas/APO-1 (CD95) elicits a characteristic programmed death response in susceptible cells. Using a genetic selection based on protein-protein interaction in yeast, we have identified two gene products that associate with the intracellular domain of Fas: Fas itself, and a novel 74 kDa protein we have named RIP, for receptor interacting protein. RIP also interacts weakly with the p55 tumor necrosis factor receptor (TNFR1) intracellular domain, but not with a mutant version of Fas corresponding to the murine lprcg mutation. RIP contains an N-terminal region with homology to protein kinases and a C-terminal region containing a cytoplasmic motif (death domain) present in the Fas and TNFR1 intracellular domains. Transient overexpression of RIP causes transfected cells to undergo the morphological changes characteristic of apoptosis. Taken together, these properties indicate that RIP is a novel form of apoptosis-inducing protein.

Amino Acid Sequence↗
PubMed1995

Immunohistochemical localization of a Shaker-related voltage-gated potassium channel protein in Schistosoma mansoni (Trematoda: Digenea).

We have recently isolated a cDNA (SKv1.1) encoding a Shaker-related K+ channel from the human parasitic trematode Schistosoma mansoni. In order to better understand the functions of SKv1.1 protein, the distribution of SKv1.1 protein in adult S. mansoni was analyzed by immunohistochemistry using a region-specific antibody. SKv1.1 proteins were widely expressed in the nervous and muscular systems. The strongest immunoreactivity (IR) was observed in the nervous system of both male and female. In the nervous system, IR for SKv1.1 proteins was localized in cell bodies and nerve fibers of the anterior ganglia, the central commissure, and the main nerve cords. IR was also observed in the dorsal and the ventral peripheral nerve nets, fine nerve fibers entering into a variety of structures such as the dorsal tubercles, longitudinal and ventral muscle fibers, and oral and ventral suckers. In the muscular system, SKv1.1 proteins were localized to the longitudinal, circular, and ventral muscle fibers of male as well as in isolated muscle fibers where native A-type K+ currents were measured. Moderate IR was also seen in a large number of cell bodies in the parenchyma. These results indicate that SKv1.1 protein may play an important role in the regulation of the excitability of neurons and muscle cells of S. mansoni.

Amino Acid Sequence↗
PubMed1995

Iron(II) is a modulator of ryanodine-sensitive calcium channels of cardiac muscle sarcoplasmic reticulum.

Iron is examined for its ability to modify Ca2+ transport across sarcoplasmic reticulum (SR) and to alter the binding of [3H]ryanodine to its high-affinity site on the Ca2+ release channel complex of SR preparations from rat heart. Iron(III) (added as ferric chloride) has negligible activity on active Ca2+ accumulation into SR and on the binding of [3H]ryanodine. In contrast, Fe(II) (added as ferrous sulfate) is a potent inhibitor of both Ca(2+)-induced Ca2+ release (IC50 of 29 microM) and DXR-induced Ca2+ release (IC50 of 14 microM). Iron(II) enhances the rate of active Ca2+ uptake into SR vesicles, mimicking the actions of the known SR Ca2+ channel blocker ruthenium red. The underlying mechanism of Fe(II) on SR Ca2+ transport is shown to be a direct and potent action on the ryanodine receptor. Fe(II) inhibits the binding of [3H]ryanodine when assayed in the presence of 5 microM Ca2+ with an IC50 of 4 microM and in an apparently cooperative manner (nH = 1.7). In the presence of physiological (1 mM) Mg2+, Fe(II) decreases the sensitivity of ryanodine receptors toward activation by Ca2+ shifting EC50 from 18 to 35 microM in the absence and presence of 5 microM Fe(II), respectively, without significant decrease in maximum [3H]ryanodine occupancy. In the presence of 5 microM Ca2+ and 1 mM Mg2+, Fe(II) decreases the potency of doxorubicin (DXR) on [3H]ryanodine binding (shifts EC50 from 8 to 24 microM in the absence and presence of 5 microM Fe(II)). These results suggest that Fe(II) competes with Ca2+ at the activator sites on the channel complex. The actions of Fe(II) on ryanodine receptor function is not correlated with membrane lipid peroxidation of SR vesicles since Fe(II) does not produce detectable changes in malondialdehyde using the thiobarbituric acid assay. These results demonstrate a direct inhibition of the Ca2+ release channel of cardiac SR by Fe(II) which may be important in pathological states of the heart during iron overload.

Animals↗
PubMed1995

Depression and anxiety in an 85-year-old woman with a toxic nodular goiter.

Depression is commonly encountered in medical settings and often may be a symptom of an underlying medical illness. This case report illustrates the disabling symptoms of anxiety and depression that can accompany a toxic nodular goiter, and underscores the importance of both accurate psychiatric diagnosis and appropriate medical evaluation in the assessment of psychiatric disorders in the elderly.

Aged↗
PubMed1995

Analysis of the kinetics and voltage-dependency of transient and delayed K+ currents in muscle fibers isolated from the flatworm Schistosoma mansoni.

There are two distinct voltage-dependent K+ currents in muscle fibers freshly isolated from the human flatworm parasite S. mansoni. Present is a delayed rectifier current with a tau act of 17 msec and tau inact > 3 sec. The delayed rectifier is very resistant to steady-state inactivation, with over 40% of the current non-inactivating, and over 15 sec required for the maximum inactivation of the other portion. The current is resistant to block by extracellular tetraethylammonium, is half-blocked by 10 mM 4-aminopyridine, and is insensitive to dendrotoxin. Also present is an "A" current with tau act < 1 msec and tau inact < 15 msec. The "A" current, like the delayed rectifier current, is resistant to block by external tetraethylammonium and is insensitive to dendrotoxin. Three micromoles of 4-aminopyridine produce a half-blockade of the "A" current. These two K+ currents are very similar to a delayed rectifier and "A" currents that have been described in a number of lower and more advanced animals.

4-Aminopyridine↗
PubMed1995

Conformational changes in subdomain 2 of G-actin: fluorescence probing by dansyl ethylenediamine attached to Gln-41.

Gln-41 on G-actin was specifically labeled with a fluorescent probe, dansyl ethylenediamine (DED), via transglutaminase reaction to explore the conformational changes in subdomain 2 of actin. Replacement of Ca2+ with Mg2+ and ATP with ADP on G-actin produced large changes in the emission properties of DED. These substitutions resulted in blue shifts in the wavelength of maximum emission and increases in DED fluorescence. Excitation of labeled actin at 295 nm revealed energy transfer from tryptophans to DED. Structure considerations and Cu2+ quenching experiments suggested that Trp-79 and/or Trp-86 serves as energy donors to DED. Energy transfer from these residues to DED on Gln-41 increased with the replacement of Ca2+ with Mg2+ and ATP with ADP. Polymerization of Mg-G-actin with MgCl2 resulted in much smaller changes in DED fluorescence than divalent cation substitution. This suggests that the conformation of loop 38-52 on actin is primed for the polymerization reaction by the substitution of Ca2+ with Mg2+ on G-actin.

Actins↗
PubMed1995

Cloning and functional expression of a Shaker-related voltage-gated potassium channel gene from Schistosoma mansoni (Trematoda: Digenea).

We have isolated a cDNA (SKv1.1) encoding a Shaker-related K+ channel from an adult cDNA library of the human parasitic trematode Schistosoma mansoni. The deduced amino acid sequence (512 aa, 56.5 kDa) contains 6 putative membrane-spanning domains (S1-S6) and a pore-forming domain (H5). SKv1.1 is grouped in the Shaker family, but forms a unique branch within this family, on the basis of dendrogram analysis. SKv1.1 shows significant sequence identity with most other Shaker channels, with 64-74% identity in the core region (S1-S6). It has the highest sequence identity with the K+ channel (Ak01a) from Aplysia. Northern blot analysis detected a single primary transcript of 2.8 kb. Southern blot analysis indicated that SKv1.1 is present as a single copy in the genomic DNA of S. mansoni. Expression of SKv1.1 in Xenopus oocytes produced a rapidly activating and inactivating outward K+ current which is highly sensitive to 4-aminopyridine, but is insensitive to tetraethylammonium, mast cell degranulating peptide, dendrotoxin and charybdotoxin. The presence of a Shaker homologue in Schistosoma suggests that Sh subfamilies may exist in other lower invertebrates as well as platyhelminths.

Amino Acid Sequence↗
PubMed1995

Molecular and biochemical characterization of two meta-cleavage dioxygenases involved in biphenyl and m-xylene degradation by Beijerinckia sp. strain B1.

Beijerinckia sp. strain B1 is able to grow on either biphenyl or m-xylene as the sole source of carbon and is capable of cooxidizing many polycyclic aromatic hydrocarbons. The catabolic pathways for biphenyl and m-xylene degradation are coinduced and share common downstream enzymatic reactions. The catabolic pathway for biphenyl degradation involves two meta-cleavage steps, one for 2,3-dihydroxybiphenyl and a second for catechol. The catabolic pathway for m-xylene involves one m-cleavage step for 3-methylcatechol. The genes for two meta-cleavage dioxygenases were cloned from Beijerinckia sp. strain B1 on a single fragment of genomic DNA. The two genes are located approximately 5.5 kb away from one another. Expression of each gene separately in Escherichia coli and analysis of the meta-cleavage dioxygenase produced showed that one enzyme was more specific for 2,3-dihydroxybiphenyl while the second was more specific for catechol. The genes for the two meta-cleavage enzymes were thus labeled bphC and xylE for 2,3-dihydroxybiphenyl 1,2-dioxygenase and catechol 2,3-dioxygenase, respectively. Nondenaturing polyacrylamide gel electrophoresis followed by enzyme activity staining showed that the two meta-cleavage dioxygenases could be easily separated from each other. Similar analyses of Beijerinckia sp. strain B1 grown on succinate, biphenyl, or m-xylene indicate that both meta-cleavage enzymes are induced when cells are grown on either biphenyl or m-xylene. The nucleotide sequence was determined for both bphC and xylE. The two genes are transcribed in opposite directions, demonstrating that at least two operons must be involved in biphenyl degradation by Beijerinckia sp. strain B1. Analysis of the deduced amino acid sequence indicates that 2,3-dihydroxybiphenyl 1,2-dioxygenase (BphC) falls into the class of meta-cleavage dioxygenases acting on dihydroxylated polycyclic aromatic hydrocarbons and is somewhat distinct from the main group of meta-cleavage dioxygenases acting on 2,3-dihydroxybiphenyl. Catechol 2,3-dioxygenase (XyIE) falls into the class of meta-cleavage enzymes acting on dihydroxylated monocyclic aromatic hydrocarbons but shows little similarity to the canonical TOL plasmid-encoded catechol 2,3-dioxygenase.

Amino Acid Sequence↗