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Biomedical subjects

D Kim

Publications and source records attributed to D Kim.

At least 379 records · Page 21Linked to original sources
PubMed1993

Dual control of heat shock response: involvement of a constitutive heat shock element-binding factor.

Heat shock factor (HSF) has been implicated as the key regulatory protein in the heat shock response. Our studies on the response of rodent cells to heat shock or sodium arsenite indicate that a high level of HSF-DNA-binding activity, by itself, is not sufficient for the induction of hsp70 mRNA synthesis; furthermore, a high level of HSF binding is also not necessary for this induction. Analysis of the binding of protein factors to the heat shock element (HSE) in extracts of stressed rodent cells indicates that the regulation of heat shock response involves the heat-inducible HSF and a constitutive HSE-binding factor. Our results also suggest that overexpression of human hsp70 may decrease the level of heat-induced HSF-HSE-binding activity in rat cells.

Animals↗
PubMed1993

Transcription mapping and functional analysis of the protein tyrosine/serine phosphatase (PTPase) gene of the Autographa californica nuclear polyhedrosis virus.

The protein tyrosine/serine phosphatase (PTPase) gene of the Autographa californica nuclear polyhedrosis virus yields two major transcripts of approximate sizes 3.1 and 3.9 kb. Both of these are very late transcripts, which accumulate to maximal levels more than 30 hr postinfection. The smaller transcript initiates at the T of an ATAAG sequence that lies 22 bp upstream of the putative start codon of the gene. The larger transcript initiates at the first A of a TTAAG sequence that lies approximately 798 bp further upstream. Thus, the larger transcript is made by transcribing through the entire hr1 region, which lies just 60 bp upstream of the putative translation start site. We have expressed the product of this gene as a fusion protein with glutathione-S-transferase and have shown that it has PTPase activity similar to that of the vaccinia virus H1 gene product: It dephosphorylates both protein phosphotyrosines and phosphoserines/phosphothreonines, and it is inhibited by vanadate, but not by okadaic acid.

Amino Acid Sequence↗
PubMed1993

Activation of a nonselective cation channel by swelling in atrial cells.

Cell swelling has been shown to increase the permeability of the plasma membrane to ions such as K+, Na+, Ca2+ or Cl- in many types of cells. In cardiac cells, swelling has been reported to increase Cl- conductance, but whether cation-selective currents are activated by swelling is not known. Low Cl- or Cl(-)-free solutions were used to study the presence of such currents. Lowering the osmolarity of the extracellular medium from 299 to 219 mOsm resulted in cell swelling and concurrent activation of a cation-selective whole-cell current. When cell-attached patches were formed on swollen cells, opening of bursting single channel currents were observed in 18% of the patches studied. Ion substitution experiments indicated that the channel discriminated poorly among monovalent cations, and was impermeable to Cl-. The channel was permeable to Ca2+. In symmetrical 140 mM K+, the current-voltage relation was linear with a single channel conductance of 36 +/- 3 pS. Depolarization increased channel open probability. Interestingly, depending on the membrane patch studied, application of negative pressure to the pipette caused either an increase or a decrease in the open probability of the channel already activated by swelling. Thus, the sensitivity to tension of the swelling-activated channel was different from those of previously reported stretch-activated channels. These findings suggest that nonselective cation channels exist in rat atrial cells and may be involved in swelling-induced changes in cell function.

Animals↗
PubMed1993

Stellate ganglion drives sympathetic regulation of cochlear blood flow.

The functional properties of the sympathetic fibers innervating the cochlea are not well understood. Adrenergic fibers supplying lateral wall structures of the cochlea have been observed terminating on radiating arterioles and collecting venules. Adrenergic fibers also terminate as 'free' endings in the spiral osseous lamina. Stimulation or transection of sympathetic fibers originating from superior cervical chain and supplying the cochlea have yielded mixed results concerning many aspects of cochlea physiology. In order to clarify the origin of sympathetic fibers and their role in control of cochlear blood flow (CBF), we examined the effect of electrical stimulation of the stellate ganglion (ESS) and transection of postganglionic fibers from the stellate on CBF measured by laser Doppler flowmetry and on systemic blood pressure (BP) in the guinea pig. ESS produced a 20-35% increase in BP and 10-15% decrease in CBF. The decrease in CBF presumably reflects the net result of increased perfusion pressure, local autoregulatory mechanisms, and a direct sympathetic-induced vasoconstriction. Section of the immediate postganglionic sympathetic trunk had little or no effect on the ESS-related change in BP; however, it eliminated the CBF reduction. Intravenously infused beta 1-blocker diminished the BP increase due to ESS, while the electrically-evoked reduction in CBF remained. Local application of an alpha-blocker on the round window blocked ESS evoked CBF reductions without altering the BP increase. These data confirm the functional role of sympathetic projections from the stellate ganglion in CBF regulation in guinea pig.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic Fibers↗
PubMed1993

Atherectomy of the subclavian artery for patients with symptomatic coronary-subclavian steal syndrome.

OBJECTIVES: This study addresses the efficacy of directional atherectomy in the subclavian artery for the relief of angina in patients with the coronary-subclavian steal syndrome. In addition, we review the histologic findings from the atherectomy specimens. BACKGROUND: The coronary-subclavian steal syndrome may occur after internal mammary-coronary artery bypass grafting. It is due to a stenosis in the subclavian artery proximal to the origin of the internal mammary artery and causes frank ischemia to the area supplied by the graft. Currently, surgery is the corrective procedure of choice. METHODS: In three patients with severe subclavian artery stenoses and unstable angina, directional atherectomy was performed using a peripheral atherectomy catheter through a percutaneous femoral approach. The patients ranged from 43 to 71 years of age and had undergone internal mammary-coronary artery bypass grafting 3 to 10 years previously. Each patient had severe peripheral vascular and cerebrovascular disease. RESULTS: All three patients had immediate symptomatic relief after the atherectomy, and postprocedure exercise testing demonstrated improved cardiac function. Two patients remain asymptomatic at 7 and 8 months, respectively; the third patient developed unstable angina 9 months later because of severe restenosis that was again successfully treated with atherectomy. Histologic examination of the specimens revealed atherosclerotic plaque, occasionally with adventitia. The specimen from the repeat atherectomy showed severe intimal hyperplasia. CONCLUSIONS: Directional atherectomy appears to be a safe and effective treatment for coronary-subclavian steal syndrome. This procedure may be the treatment of choice for patients in whom a vascular bypass operation is not feasible.

Adult↗
PubMed1993

Molecular basis of the increase in invertase activity elicited by gravistimulation of oat-shoot pulvini.

An asymmetric (top vs. bottom) increase in invertase activity is elicited by gravistimulation in oat-shoot pulvini starting within 3 h after treatment. In order to analyze the regulation of invertase gene expression in this system, we examined the effect of gravistimulation on invertase mRNA induction. Total RNA and poly (A)+RNA, isolated from oat pulvini, and two oligonucleotide primers, corresponding to two conserved amino-acid sequences (NDPNG and WECPD) found in invertase from other species, were used for the polymerase chain reaction (PCR). A partial-length cDNA (550 base pairs) was obtained and characterized. There was a 52% deduced amino-acid sequence homology to that of carrot beta-fructosidase and a 48% homology to that of tomato invertase. Northern blot analysis showed that there was an obvious transient accumulation of invertase mRNA elicited by gravistimulation of oat pulvini. The mRNA was rapidly induced to a maximum level at 1 h following gravistimulation treatment and gradually decreased afterwards. The mRNA level in the bottom half of the oat pulvinus was significantly higher (five-fold) than that in the top half of the pulvinus tissue. The induction of invertase mRNA was consistent with the transient enhancement of invertase activity during the graviresponse of the pulvinus. These data indicate that the expression of the invertase gene(s) could be regulated by gravistimulation at the transcriptional and/or translational levels. Southern blot analysis showed that there were four genomic DNA fragments hybridized to the invertase cDNA. This suggests that an invertase gene family may exist in oat plants.

Amino Acid Sequence↗
PubMed1993

Magnesium sulfate for the treatment of bronchospasm complicating acute bronchitis in a four-months'-pregnant woman.

A four-months'-pregnant woman without a prior history of asthma presented to the emergency department with acute bronchitis compounded by bronchospasm. The patient failed to respond adequately to aggressive treatment with conventional therapy. Prior to hospital admission, a bolus of 3 g IV magnesium sulfate was infused with complete abatement of her bronchospasm, significantly increasing peak expiratory flow rate without any significant side effects. The patient was discharged home and remained asymptomatic thereafter.

Adult↗
PubMed1993

Isolation and characterization of complement receptor type 1 from rat glomerular epithelial cells.

Complement receptor type 1 (C3b/C4b receptor, CR1) is known to be present in human glomerular epithelial cells (GEC) in vivo. The presence of CR1 has not been documented in rat glomeruli, although cultured rat GEC appear to express CR1 based upon their ability to rosette with complement-coated erythrocytes. In this study, we establish that CR1 is present in cultured rat GEC: (1) by isolating a 200 kDa protein from detergent-solubilized cultured rat GEC through the use of C3b affinity chromatography; (2) by Western blotting studies demonstrating reactivity of anti-human CR1 antibodies with this protein from cultured GEC; and (3) by demonstrating that C3b binding to GEC monolayers exhibits low affinity and that an estimate of the number of binding sites is 6700 per cell, both of which are comparable to that seen for CR1 in human blood cells. Furthermore, we show that CR1 is also present in rat glomeruli by Western blotting studies with anti-human CR1. Anti-human CR1 also identifies a 70 kDa protein from cultured GEC and isolated glomeruli. This 70 kDa protein is likely to be the CR1-like protein, designated Crry, which was initially identified in the mouse and has significant homology to human CR1. Crry may be present in rat GEC instead of decay accelerating factor, which is present in human GEC.

Animals↗
PubMed1993

Comparative evaluation of clinically available inferior vena cava filters with an in vitro physiologic simulation of the vena cava.

PURPOSE: A physiologic in vitro model of the human inferior vena cava (IVC) was developed to evaluate the clot-trapping efficiency of various IVC filters. MATERIALS AND METHODS: The flow model closely simulates the physical parameters of the human IVC in fluid viscosity, specific gravity, temperature, and pulsatility; blood flow velocity, volume, and inherent turbulence; and vein orientation, wall compliance, and clot composition. Five filters--Greenfield (G), Bird's Nest (BN), Vena Tech (VT), Simon nitinol (SN), and titanium Greenfield (TG)--were compared by using two vena cava and blood clot sizes and horizontal and vertical orientation of the model. RESULTS: Each filter varied significantly in its clot-capturing efficiency, depending on vena cava size and orientation and emboli size. Overall, decreasing rank order in filter clot-trapping efficiency was SN, BN, VT, TG, and G. CONCLUSION: The in vitro model of the human IVC is an alternative to multicenter clinical trials in evaluating the relative clot-trapping efficiency of various IVC filters.

Equipment Design↗
PubMed1993

Transient analysis of macromolecular transport across microvascular wall and into interstitium.

We studied the dynamics of macromolecular transport across the microvascular wall in the hamster cheek pouch using intravital microscopy and digital video-image analysis. We used fluorescein isothiocyanate-dextrans of 70,000 and 150,000 Da (FITC-Dextran 70 and 150, respectively) as tracers. We applied our mathematical model and our in vivo calibration to determine the diffusion coefficient (D) and the average fluid velocity (V) in the microvascular wall and in the interstitium from the experimental data. The value of D for FITC-Dextran 70 was 0.90 +/- 0.04 x 10(-11) cm2/s in the wall and 1.29 +/- 0.05 x 10(-8) cm2/s in the interstitium. In both regions, V was 2.05 +/- 0.05 x 10(-8) cm/s. The transport parameters for FITC-Dextran 150 were 0.27 +/- 0.02 x 10(-11) cm2/s, 0.55 +/- 0.05 x 10(-8) cm2/s, and 1.71 +/- 0.48 x 10(-8) cm/s for D in the wall and interstitium and V, respectively. The topical application of either calcium ionophore A23187 (7 x 10(-7) M) or bradykinin (5 x 10(-7) M) increased D for FITC-Dextran 70 and 150 2-fold and V 10-fold relative to their control values. We used these values to quantify the relative importance of the diffusive and convective mechanisms in the total solute flux. Molecular diffusion dominates convective transport in both the microvascular wall and the interstitial space.

Animals↗
PubMed1993

Novel cation-selective mechanosensitive ion channel in the atrial cell membrane.

Stretch of atrial muscle causes the release of atrial natriuretic peptide, but no stretch-sensitive membrane sensors have been clearly identified so far. The existence of an ion channel that could mediate stretch-induced Ca2+ influx and subsequent release of the peptide was examined in rat atrial cells. In this report, the discovery of a novel atrial ion channel whose opening probability is extremely sensitive to either positive or negative pressure (half-maximal activation pressure, approximately 1.5 mm Hg) is described. Activation of the current by pressure applied to the pipette was observed both at the whole-cell and single-channel levels. The channel was permeable to cations including Ca2+. The channels were clustered with six to nine channels in each cluster, and several channels tended to open simultaneously in response to a graded increase in pressure for the inwardly passing current. Hypotonic swelling also activated these channels. These results show that mechanosensitive nonselective cation channels exist in atrial cells and suggest that they could be involved in beat-to-beat regulation of the atrial contraction as well as the stretch-induced expression of proto-oncogenes and secretion of atrial natriuretic peptide via increased Ca2+ entry.

Animals↗
PubMed1993

Mechanism of rapid desensitization of muscarinic K+ current in adult rat and guinea pig atrial cells.

Acetylcholine (Ach) activates the muscarinic K+ current in atrial cells via the inhibitory GTP binding protein. After activation, the whole-cell K+ current decreases rapidly (rapid desensitization) to approximately half of the initial current within approximately 20 seconds. The mechanism of this rapid desensitization was investigated in adult rat and guinea pig atrial cells. Whole-cell voltage-clamp and patch-clamp techniques were used to study the K+ current. In voltage-clamped whole cells, ACh activated a K+ current that desensitized rapidly during the initial approximately 20 seconds followed by a slower decrease over several minutes. The rapid K+ current desensitization (a rapid decrease in channel open probability) was also observed at the single-channel level in cell-attached patches and was associated with a progressive shortening of the channel open time and prolongation of the closed time. These changes in channel current and kinetics were abolished by removal of the cytoplasm (by forming inside-out patches) and were partially inhibited by phosphatase inhibitors, suggesting an involvement of cytosolic phosphatase(s) in K+ current desensitization. In inside-out patches with ACh in the pipette and GTP in the bath, the open time of muscarinic K+ channels and channel open probability were increased by 1 mM Mg(2+)-ATP (but not by the nonhydrolyzable analogue, adenylylimidodiphosphate) and decreased by alkaline phosphatase. These results suggest that the rapid K+ current desensitization in adult rat or guinea pig atrial cells is produced by changes in the gating kinetics of the K+ channel, possibly mediated via membrane-associated protein kinase and cytosolic phosphatase(s).

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1992

Murine alpha 1,3-galactosyltransferase. A single gene locus specifies four isoforms of the enzyme by alternative splicing.

We have reported the characterization of a cDNA (clone 31A) encoding bovine alpha 1,3-galactosyltransferase (alpha 1,3-GT) (Joziasse, D. H., Shaper, J. H., Van den Eijnden, D. H., Van Tunen, A. J., and Shaper, N. L. (1989) J. Biol. Chem. 264, 14290-14297). With the goal of isolating a full-length cDNA encoding murine alpha 1,3-GT we screened a cDNA library with clone 31A and isolated a 3.4-kilobase (kb) alpha 1,3-GT clone (4A). The murine coding sequence is 78% similar to that of the bovine alpha 1,3-GT cDNA, but the "stem" region (defined as the region that links the single transmembrane domain to the catalytic domain) of the murine alpha 1,3-GT encoded by clone 4A, is 31 amino acids shorter than the corresponding region of the bovine alpha 1,3-GT. To screen for heterogeneity in the murine alpha 1,3-GT transcripts, we carried out a polymerase chain reaction (PCR) analysis on mouse C127 cDNA. Four distinct transcripts were detected, which predict four isoforms of the alpha 1,3-GT polypeptide that differ only in the length of their stem region. To determine how the four different transcripts are generated from a single gene, we have established the genomic organization for murine alpha 1,3-GT. The full-length mRNA spans at least 35 kb of genomic DNA and is distributed over nine exons that range in size from 36 base pairs (bp) to approximately 2600 bp. The protein coding region is distributed over six exons, and the 5'-untranslated sequence is distributed over three exons. Comparison of the genomic DNA sequence with that of the four different mRNAs indicates that these transcripts are produced by alternative splicing of the murine pre-mRNA according to a cassette model. A tissue survey using RNA-PCR revealed the presence of four different alpha 1,3-GT transcripts in all mouse tissues and cell lines examined to date, with the notable exception of male germ cells. Additionally, although alpha 1,3-GT levels increased upon thioglycollate-induced activation of mouse peritoneal macrophages, the ratio of the alpha 1,3-GT isoforms was essentially unchanged. Similar results were obtained upon retinoic acid-induced differentiation of murine F9 teratocarcinoma cells. Lastly, a similar PCR analysis of bovine cDNA produced only a single DNA fragment, corresponding to bovine cDNA clone 31A.

Amino Acid Sequence↗
PubMed1992

Prevention of carryover contamination in the detection of beta S and beta C genes by polymerase chain reaction.

As the polymerase chain reaction (PCR) process becomes a common tool in genetic diagnostic laboratories, prevention of carryover contamination from previous PCR amplifications has become an urgent topic. A PCR carryover prevention technique, utilizing deoxyuridine triphosphate (dUTP) and uracil DNA glycosylase (UDG), has been described recently. We report on its adaptation to a diagnostic system for detecting hemoglobin SS and SC diseases. Excellent amplification was achieved by increasing the dUTP and MgCl2 concentrations. dU-containing DNA could be analyzed by restriction endonucleases to distinguish the beta S from beta A gene using Ddel, but two other restriction enzymes, Bsu361 (replacement for MstII by the manufacturer) and CvnI, can no longer be used. The dU-containing PCR products retained their hybridization specificity with allele-specific oligonucleotide (ASO) probes for the beta A, beta S, and beta C genes. The PCR carryover prevention technique is easy to use and takes only 20 additional minutes. It should be extremely useful to genetic diagnostic laboratories where PCR is repeated daily and carryover contamination may thus lead to misdiagnoses.

Base Sequence↗
PubMed1992

Role of superficial femoral artery puncture in the development of pseudoaneurysm and arteriovenous fistula complicating percutaneous transfemoral cardiac catheterization.

Of 13,203 transfemoral diagnostic and therapeutic cardiac catheterization procedures performed between January 1, 1980 and December 31, 1990, 73 (0.55%) were complicated by pseudoaneurysm (PA) formation, and 15 (0.11%) by arteriovenous fistulas (AVF). The rate of PA increased progressively from 0.44% (1980-1987), to 0.59% (1987-1989), to 0.92% (1990), with no corresponding change in the incidence of AVF. The rising incidence of PA complicating transfemoral cardiac catheterization was associated closely with the use of larger diameter catheters and aggressive antiocoagulation during coronary interventions, but findings during surgical repair suggested that puncture of the superficial femoral (SFA), rather than the common femoral artery (CFA), was an important avoidable cause of some PA and AVF. A technique for fluoroscopic localization of the puncture site to avoid inadvertent SFA puncture and the associated increased risk of complication is proposed.

Aneurysm↗
PubMed1992

Constitutive HSP70: oligomerization and its dependence on ATP binding.

The constitutive HSP70 purified from CHO cells, which indicated a single band in SDS-polyacrylamide gel electrophoresis, showed multiple bands in native-polyacrylamide gel electrophoresis. These results indicate that the protein may exist in oligomeric forms. After crosslinking the oligomers with glutaraldehyde, SDS-polyacrylamide gel electrophoresis showed three protein bands of molecular weight 70 kDa, 153 kDa, and 200 kDa corresponded to monomer, dimer, and trimer, respectively. The relative amount of oligomeric forms was dependent upon ATP concentrations: it increased upon hydrolysis of ATP or decreased upon incubation with high concentrations of ATP (1-10 mM). Autoradiographic analysis of the native polyacrylamide gel electrophoresis of HSP70 following incubation with [gamma-32P]ATP revealed that ATP bound to only monomer. These results suggest that the equilibrium between oligomeric forms is dependent on ATP concentrations. Nonetheless, during heat shock, both monomer and oligomer might be indistinguishably associated with some proteins, probably denatured proteins.

Adenosine Triphosphate↗