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J Kim

Publications and source records attributed to J Kim.

At least 883 records · Page 49Linked to original sources
PubMed1995

A study of Na-DNA films containing NaCl via scanning electron and tunneling microscopies.

Unoriented films of Na-DNA were prepared by dessicating a gel with different amounts of NaCl. For low salt concentrations, the resulting films were smooth and patternless. For high salt concentrations, the resulting films had visible patterns that were very similar to those recently reported by Sclavi et al. [(1994) Biopolymers, Vol. 34, pp. 1105-1113]. Scanning electron and tunneling microscopies and electron dispersive spectroscopy studies were used to study the spatial distribution of NaCl throughout these films. Two main conclusions were reached about the NaCl: (1) some NaCl is distributed throughout every film, and (2) the visible patterns observed in films with a large amount of NaCl were caused by the growth of NaCl crystals during the dehydration process.

Animals↗
PubMed1995

The non-histone chromosomal protein HMG-I(Y) contributes to repression of the immunoglobulin heavy chain germ-line epsilon RNA promoter.

The rate of germ-line RNA transcription correlates with the rate of immunoglobulin heavy chain isotype switching. A promoter element for the transcription of RNA from the germ-line mouse immunoglobulin epsilon heavy chain constant region gene is induced by interleukin(IL)-4 and lipopolysaccharide, and is bound at its transcription initiation sites by an IL-4-inducible nuclear protein, NF-BRE. To examine the function of the binding site for this IL-4-inducible complex, substitution mutations were introduced in the promoter. These binding site mutations increased promoter activity and decreased binding of NF-BRE. To investigate the paradox of an IL-4-inducible protein binding to a repressor site in an IL-4-inducible promoter, we determined that the non-histone chromosomal protein HMG-I(Y) binds at the transcription initiation sites of the germ-line epsilon promoter. Assays with antisera against HMG-I(Y) revealed monomeric HMG-I(Y) in nuclear extracts. Cotransfection of an expression construct directing the synthesis of anti-sense HMG-I(Y) RNA also increased promoter activity, consistent with a repressor function of HMG-I(Y). Thus, the data are most consistent with a model in which HMG-I(Y) participates in repression of promoter activity. The effects of IL-4 may include derepression at this site.

Animals↗
PubMed1995

Control of a one-link arm by burst signal generators.

The focus of this paper is the study of stability and point-to-point movement of a one-link arm. The sagittal arm has two musculotendon actuators, two neural oscillators that generate burst signals as motoneuron inputs, and spindles and Golgi tendon organs for extrinsic reflex feedbacks. It is shown that coactivation leads to intrinsic position and velocity feedback, and that the tendons introduce intrinsic force and rate of force feedback. In addition, the integrating effects of the tendons are studied when the actuator is constructed from a large number of identical fibers that are excited by alpha signals whose arrival times at the fiber are randomly distributed. Each of the musculotendon actuators receives two input signals--a burst signal analogous to alpha inputs and a conventional analogue signal that represents fusimotor input to the spindles. The process of combining burst signals and conventional analogue signals is studied. Simulation results show that the movement of the system with burst signals as inputs has overshoot and speed similar to the system with analogue signals.

Biomechanical Phenomena↗
PubMed1995

Transcriptional control of the Saccharomyces cerevisiae ADH1 gene by autonomously replicating sequence binding factor 1.

Autonomously replicating sequence (ARS)-binding factor 1 (ABF1) is a multifunctional protein involved in transcriptional activation and repression, as well as DNA replication, in yeast. The ADH1 gene, encoding alcohol dehydrogenase 1, contains two ABF1 consensus binding sites in the promoter and the coding regions. To examine the effect of ABF1 on expression of the ADH1 gene, we constructed an ADH1-lacZ fusion plasmid. Both ABF1 binding sites appeared to be transcriptional activators because deletions and mutations of these sites decreased transcriptional activity. The ABF1 binding sites also acted in an orientation-independent manner when a synthetic ABF1 binding site was inserted into the yeast CYC1 gene lacking its transcriptional activation region. A gel mobility shift assay showed that ABF1 bound in vitro to both ABF1 binding sites in the promoter and coding regions. In a glycerol medium the degree of activation by ABF1 was higher than in a glucose medium. The expression of ADH1 was activated synergistically by both ABF1 binding sites. These observations suggest that ABF1 transactivates the ADH1 gene through its binding sequences in both the promoter and coding regions.

Alcohol Dehydrogenase↗
PubMed1995

The glucose-dependent transactivation activity of ABF1 on the expression of the TDH3 gene in yeast.

Autonomously replicating sequence binding factor 1 (ABF1) has been implicated in the control of a variety of gene expressions in Saccharomyces cerevisiae. In this paper evidence is presented that ABF1 is involved in the glucose-dependent expression of the TDH3 gene which encodes glyceraldehyde-3-phosphate dehydrogenase. ABF1 binds to consensus sites located between -420 and -250, and between +77 and +200, and acts as a transactivator in an orientation-independent manner on both upstream and downstream sites. TDH3-lacZ fusions having an ABF1 consensus motif showed glucose-dependent expression of TDH3, whereas in the abf1 mutant strain JCA35 glucose-dependent expression disappeared. These findings suggest that ABF1 functions as a glucose-dependent transactivator for the expression of the TDH3 gene.

Consensus Sequence↗
PubMed1995

Prophylaxis against the systemic hypotension induced by propofol during rapid-sequence intubation.

The objective of this study was to determine the effectiveness of two prophylactic approaches against the anticipated hypotension induced by propofol during rapid-sequence intubation. Thirty-six male or female nonpremedicated ASA class I-II patients aged 21-60 yr undergoing elective outpatient surgery were included in the study. Patients were randomly allocated to receive pre-induction ephedrine sulphate (70 micrograms x kg(-1)iv), pre-induction volume loading (12 ml x kg(-1) Ringer's lactate) or no treatment. Rapid-sequence intubation with cricoid pressure was then performed with propofol (2.5 mg. x kg(-1)) and succinylcholine (1.5 mg x kg(-1). The lungs were subsequently ventilated with 0.25-0.5% isoflurane in a 2:1 N2O/O2 mixture. Vecuronium was given once neuromuscular function had recovered from the succinylcholine. Heart rate and systemic arterial blood pressure were measured non-invasively before induction, after propofol administration and every minute for ten minutes after intubation. Pre-induction volume loading prevented the hypotension observed before surgical stimulation in control and ephedrine groups. Moreover, pre-induction volume loading was not associated with increases in heart rate after intubation as was ephedrine administration. The intubating conditions were excellent to satisfactory in most patients and the overall incidence of adverse events during intubation was mainly due to pain during injection of propofol. The present study showed that preoperative volume loading is more efficacious than pre-induction administration of ephedrine sulphate in maintaining haemodynamic stability during rapid-sequence induction with propofol and succinylcholine. In addition, propofol in combination with succinylcholine provides excellent conditions for rapid-sequence intubation.

Adult↗
PubMed1995

The rural and global medical informatics consortium and network for radiology services.

Telemedicine systems that provide health delivery services to rural clinics and hospitals are being demonstrated in clinical settings. This paper summarizes the research and consortia projects at the University of Arizona Medical Center. The paper describes the Rural and Global Picture Archiving and Communications (PACS) environment developed under a National Science Foundation grant. The Rural and Global PACS environment includes many workstations, database, and networking components and is treated as a large distributed system. These components are described in this paper. The multimedia services for radiology provided by the Rural and Global PACS are described and their performance is measured. Finally, the current research work using the Open Software Foundation's distributed computing environment (OSF DCE) services is described. An OSF DCE testbed for the Rural and Global PACS is described and the rationale of using OSF DCE in the project is presented.

Arizona↗
PubMed1995

The Z type variation of human alpha 1-antitrypsin causes a protein folding defect.

Emphysema is often associated with the Z type mutation of alpha 1-antitrypsin, which causes aggregation of the molecule in the liver and consequent plasma deficiency. The aggregation appears to be due to loop-sheet polymerization, although why the mutant protein polymerizes in vivo is unclear. Here we show that, unlike wild type antitrypsin, which folds in minutes, the folding of Z type alpha 1-antitrypsin is extremely slow. Once folded, however, the native Z protein shows substantial stability towards urea and incubation at 37 degrees C. The folding defect in Z antitrypsin leads to accumulation of an intermediate and it is the intermediate rather than the native protein which has a high tendency to aggregate.

Amino Acids↗
PubMed1995

Surface attachment of Salmonella typhimurium to intestinal epithelia imprints the subepithelial matrix with gradients chemotactic for neutrophils.

During intestinal disease induced by Salmonella typhimurium transepithelial migration of neutrophils (PMN) rapidly follows attachment of the bacteria to the epithelial apical membrane. Among the events stimulated by these interactions is the release of chemotaxins that guide PMN through the subepithelial matrix and subsequently through the epithelium itself (McCormick, B.A., S.P. Colgan, C. Delp-Archer, S.I. Miller, and J.L. Madara. 1993. J. Cell Biol. 123:895-907). Given the substantial volume flow that normally characterizes matrix compartments underlying transporting epithelia, it is unclear how such transmatrix signaling is sustained. Here we show that when underlying matrices are isolated from biophysically confluent polarized monolayers of the human intestinal epithelial cell line T84, they fail to support substantial transmatrix migration of PMN unless an exogenous chemotactic gradient is imposed. In contrast, such matrices isolated from confluent monolayers apically colonized with S. typhimurium support spontaneous transmatrix migration of PMN. Such chemotactic imprinting of underlying matrices is resistant to volume wash and is paralleled by secretion of the known matrix-binding chemokine IL-8. Chemotactic imprinting of the matrix underlying S. typhimurium-colonized monolayers is dependent on epithelial protein synthesis, is directional implying the existence of a gradient, and is neutralized by antibodies either to IL-8 or to the IL-8 receptor on PMN. An avirulent S. typhimurium strain, PhoPc, which attaches to epithelial cells as efficiently as wild-type S. typhimurium, fails to induce basolateral secretion of IL-8 and likewise fails to imprint matrices. Together, these observations show that the epithelial surface can respond to the presence of a luminal pathogen and subsequently imprint the subepithelial matrix with retained IL-8 gradients sufficient to resist washout effects of the volume flow that normally traverses this compartment. Such data further support the notion that the primary role for basolateral secretion of IL-8 by the intestinal and likely other epithelia is recruitment of PMN through the matrix to the subepithelial space, rather than directing the final movement of PMN across the epithelium.

Bacterial Proteins↗
PubMed1995

Regulation of Xenopus laevis estrogen receptor gene expression is mediated by an estrogen response element in the protein coding region.

To investigate the 17 beta-estradiol induction of the mRNA coding for the Xenopus laevis estrogen receptor (XER), we cloned the promoter and the 5'-flanking region of the ER gene. Transcription initiation sites were identified by primer extension, and confirmed by the polymerase chain reaction. The promoter and 5'-flanking region contain an imperfect TATA box and a potential CAAT box at -51. Sequence analysis and transfections indicated that no functional estrogen response element (ERE) was present in approximately 3 kb of 5'-flanking region. An imperfect ERE, GGTCAGTTTGACG, which differs from the consensus ERE sequence by 1 nucleotide, was detected in the protein coding region of the gene, approximately 480 nucleotides downstream of the transcription initiation site. In transient transfections using a simple promoter containing two copies of this Xenopus estrogen receptor ERE (XERE), we observed an estrogen-dependent increase in CAT activity of four- to five-fold, to a level approximately 20-fold greater than the activity of the control plasmid lacking the XEREs. In competition gel mobility-shift assays, the XERE exhibited a weak, but clearly detectable, ability to compete for binding of human ER to a labeled consensus ERE. Because it exhibits sequence-specific binding to the ER in competition gel mobility-shift assays, and is able to confer estrogen-dependent transcription on a simple synthetic promoter, the novel XERE, located in the protein coding region of the XER gene appears to represent a weak, but functional, ERE.

Amino Acid Sequence↗
PubMed1995

Pharmacodynamics of subconjunctival gentamicin after experimental cataract operations and traumatic lacerations.

We addressed the concern whether retinal toxicity could occur with subconjunctival gentamicin injections after cataract operations or traumatic corneoscleral lacerations. The lacerations were created along the superior limbus of rabbit eyes and the lenses removed. We sutured the right eyes to mimic a cataract operation and the left eyes remained unsutured to mimic a traumatic corneoscleral laceration. Vitreous humor samples were obtained at 1, 2, 4, 8 and 12 hours after the subconjunctival injection, but in no case did vitreal concentration approach retinotoxic levels (> 133 micrograms/ml).

Animals↗
PubMed1995

Ovine bone marrow extracellular matrix and soluble protein extraction: fetuin amino terminus microheterogeneity.

In this article, the authors describe a new method using phosphate-buffered saline for the initial extraction of extracellular matrix (ECM) and soluble proteins from hematologic tissues. Direct comparisons between this method and previously reported methods demonstrate superior total protein yields with the novel technique in a fraction of the time for these ovine hematologic tissues: bone marrow, marrow aspirate, spleen, liver, and blood. Analysis by one-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis and silver staining demonstrate comparable protein patterns with this method and a previously reported method. This method also successfully extracts the ECM glycoproteins fibronectin and laminin as well as the proteoglycan, chondroitin sulfate from marrow. These findings are demonstrated by Western and dot blotting. Bone marrow ECM and soluble proteins extracted by the novel method stimulate myeloid progenitor growth in a methylcellulose assay. Using an assay for elastase inhibitory capacity, the authors demonstrate that alpha 1-proteinase inhibitor, the principal inhibitor of neutrophil elastase, is present and that its activity is preserved in bone marrow samples extracted with this team's method. In contrast, very low total protein yields are obtained with the method used previously to recover hemonectin, a rabbit bone marrow ECM granulocytic cytoadhesion molecule. This team's novel procedure, which extracts ECM and soluble proteins from small samples of tissue in a rapid, efficient, and reproducible manner, greatly enhances the analysis of these proteins from tissue culture, animal, and human clinical samples. In addition, with purification by chromatofocusing chromatography and molecular sieving gel electrophoresis, N-terminal amino acid sequencing could be performed on a developmentally regulated marrow protein with biochemical properties similar to those of hemonectin and the plasma protein fetuin. The authors propose that this novel technique be used for the initial extraction of ECM and soluble proteins from hematologic tissues and that subsequent, definitive recovery of insoluble proteins be accomplished using previously reported, though less efficient, methods.

Amino Acid Sequence↗
PubMed1995

Acute renal insufficiency in ibuprofen overdose.

Since the introduction of ibuprofen as a nonprescription drug in the US, there have been reports of significant toxicity associated with large ingestions (> 400 mg/kg) in both children and adults. Acute renal insufficiency is a rare, reversible effect of ibuprofen overdose documented in adults, but we could find no published pediatric cases. We report a case of a healthy two-year-old boy, without a previous history of renal problems, who developed reversible acute renal insufficiency after a toxic ingestion of approximately 640 mg/kg ibuprofen. By 11 hours, his initially normal creatinine began to rise, reaching a peak value of 181 mmol/L (2.1 mg/dl) by 27 hours. His urinalysis showed moderate microscopic hematuria without the presence of casts or proteinuria. No problems arose with fluid management. Normalization of his renal function occurred by 72 hours. A serum ibuprofen concentration obtained by high-performance liquid chromatography and drawn approximately four hours after ingestion was 1724 mumol (therapeutic serum concentration, 50-250 mumol). This case demonstrates that acute, reversible renal insufficiency can occur in healthy children after a severe overdose of ibuprofen; hence, renal function should be monitored in such instances.

Acute Kidney Injury↗
PubMed1995

Predicting perioperative stroke.

The purpose of this review is to examine the incidence and mechanisms of perioperative stroke and to identify possible associated risk factors. The perioperative period can be subdivided into preoperative, intraoperative, and postoperative periods; we focus here on assessment in the preoperative period, as this is the time when risk prediction usually occurs. Surgical technique itself will not be considered, nor will intraoperative monitoring to detect cerebral ischemia be considered. This review will examine perioperative stroke in relation to general surgical procedures, including peripheral vascular reconstruction, orthopedic, gynecologic, and head and neck surgery.

Anesthesia↗
PubMed1995

Regional distributions of hippocampal Na+,K(+)-ATPase, cytochrome oxidase, and total protein in temporal lobe epilepsy.

Na+,K(+)-ATPase (the sodium pump) is a ubiquitous enzyme that consumes ATP to maintain an adequate neuronal transmembrane electrical potential necessary for brain function and to dissipate ionic transients. Reductions in sodium pump function augment the sensitivity of neurons to glutamate, increasing excitability and neuronal damage in vitro. Temporal lobe epilepsy (TLE) is one disease characterized by hyperexcitability and marked hippocampal neuronal losses that could depend in part, on impaired sodium pump capacity secondary to changes in sodium pump levels and/or insufficient ATP supply. To assess whether abnormalities in the sodium pump occur in this disease, we used [3H]ouabain to determine the density of Na+,K(+)-ATPase for each anatomic region of hippocampus by in vitro autoradiography. Tissues were surgically obtained from epileptic patients with hippocampal sclerosis and compared with specimens from patients with seizures originating from temporal lobe tumors and autopsy controls. Changes in cellular population arising from neuronal losses or gliosis were assessed by protein densities derived from quantitative computerized densitometry of Coomassie-stained tissue sections. We estimated regional differences in capacity for ATP generation by determining cytochrome c oxidase (CO) activity. Principal neurons of hippocampus exhibit high levels of sodium pump enzyme. Both epilepsy groups exhibited slight but significant increases in sodium pump density/unit mass of protein in the dentate molecular layer, CA2, and subiculum as compared with autopsy controls. Greater hilar sodium pump density was also observed in sclerotic hippocampi. In contrast, CO activity was reduced in both epilepsy types throughout hippocampus. Results suggest that although sodium pump protein in surviving neurons appears to be upregulated in epilepsy, sodium pump capacity may be limited by the reduced levels of CO activity. Functional reduction in sodium pump capacity may be an important factor in hyperexcitability and neuronal death.

Autoradiography↗
PubMed1995

Sambutoxin-producing isolates of fusarium species and occurrence of sambutoxin in rotten potato tubers.

A total of 50 Fusarium isolates representing 13 species from various sources were surveyed to determine their potential to produce sambutoxin. Sambutoxin production was restricted to Fusarium sambucinum and F. oxysporum, with the exception of one isolate of F. semitectum. Sambutoxin was produced by high percentages of F. sambucinum (80.0%) and F. oxysporum (84.6%) isolates at levels of 1.1 to 101.0 (mu)g/g. In addition, 9 (42.9%) of 21 rotten potato samples were contaminated with sambutoxin at levels of 15.8 to 78.1 ng/g.

Journal Article↗