Biomedical subjects

K T Kim

Publications and source records attributed to K T Kim.

At least 19 recordsLinked to original sources

PubMed1998

Opposing effects of protein kinase A and C on capacitative calcium entry into HL-60 promyelocytes.

Treatment of HL-60 cells with thapsigargin, a microsomal Ca2+/ATPase inhibitor, led to depletion of intracellular calcium stores followed by capacitative calcium entry. Stimulation of adenylyl cyclase with forskolin enhanced thapsigargin-induced Ca2+ influx. The forskolin effect was confirmed by enhanced fluorescence quenching induced by Mn2+ entry into fura-2 loaded cells. 1,9-Dideoxy-forskolin, an inactive analog of forskolin, did not affect capacitative calcium entry. On the other hand, phorbol 12-myristate 13-acetate (PMA), an activator of protein kinase C, inhibited thapsigargin-induced Ca2+ entry. Histamine and prostaglandin E2 (PGE2) elevated intracellular adenosine 3':5'-cyclic monophosphate (cAMP) levels and enhanced the thapsigargin-induced capacitative calcium entry. Incubation with N-[2-(p-bromocynnamylamino)ethyl]-5-isoquinolinesulfonamide (H89), an inhibitor of protein kinase A (PKA), blocked the forskolin effect, and GF109203X, an inhibitor of protein kinase C (PKC), blocked the phorbol 12-myristate 13-acetate effect. The results suggest that protein kinase A regulates capacitative calcium entry positively, but that protein kinase C regulates Ca2+ influx negatively. Furthermore, after differentiation of HL-60 promyelocytes with dimethylsulfoxide to granulocytes, the inhibitory effect of phorbol 12-myristate 13-acetate became more pronounced, whereas the stimulatory effect of prostaglandin E2 did not change. This result suggests that the regulation of capacitative calcium entry by protein kinase C and protein kinase A develops differently during differentiation.

Calcium↗

PubMed1998

Characterization of Mas-7-induced pore formation in SK-N-BE(2)C human neuroblastoma cells.

Mastoparan, a peptide toxin from wasp venome, mimics receptors by stimulating the GTPase activity of guanine nucleotide binding proteins and the G-protein-coupled phospholipase C (PLC). By using Mas-7, the active analog of mastoparan, we showed that it makes pores in the plasma membrane. Treatment with Mas-7 but not Mas-17, the inactive analog, produced a concentration-dependent rise in intracellular Ca2+ concentration ([Ca2+]i) and facilitated the uptake of ethidium bromide (EtBr) (314 Da) to a sustained level during the stimulation. In addition, Mas-7 triggered the influx of lucifer yellow (457 Da), while it did not induce the influx of fura-2 (831 Da) and Evans blue (961 Da). However, the Mas-7-induced permeability was selectively prevented by the addition of La3+, Ni2+, and Co2+, but not Cd2+. This blocking activity was concentration-dependent. While the stimulatory effect of Mas-7 on PLC activity was dependent on extracellular Ca2+, the pore forming activity of Mas-7 was not effected by removal of extracellular Ca2+. These results, therefore, suggest that the mastoparan's action in pore formation is independent from its action in PLC stimulation and is negatively effected by inorganic cations.

Calcium↗

PubMed1998

Inhibitory effects of bulbocapnine on dopamine biosynthesis in PC12 cells.

The effects of bulbocapnine, an aporphine isoquinoline alkaloid, on dopamine biosynthesis in PC12 cells were investigated. Bulbocapnine showed 45.2% inhibition on dopamine content in PC12 cells at a concentration of 20 microM for 12 h. The IC50 value of bulbocapnine was 26.7 microM. Bulbocapnine at concentrations up to 80 microM was not cytotoxic towards PC12 cells. Tyrosine hydroxylase (TH) activity was inhibited by the treatment of bulbocapnine in PC12 cells (24.4% inhibition at 20 microM). Bulbocapnine at 20 microM also decreased the intracellular Ca2+ concentration by 12.9% inhibition relative to control in PC12 cells. However, TH mRNA level was not altered by bulbocapnine treatment. These results suggest that the inhibition of TH activity by bulbocapnine might be involved in at least one component of the reduction of dopamine biosynthesis in PC12 cells.

Animals↗

PubMed1998

Differential inhibition of catecholamine secretion by amitriptyline through blockage of nicotinic receptors, sodium channels, and calcium channels in bovine adrenal chromaffin cells.

We investigated the effects of amitriptyline, a tricyclic antidepressant, on [3H]norepinephrine ([3H]NE) secretion and ion flux in bovine adrenal chromaffin cells. Amitriptyline inhibited [3H]NE secretion induced by 1,1-dimethyl-4-phenylpiperazinium iodide (DMPP) and 70 mM K+. The half maximal inhibitory concentration (IC50) was 2 microM and 9 microM, respectively. Amitriptyline also inhibited the elevation of cytosolic calcium ([Ca2+]i) induced by DMPP and 70 mM K+ with IC50 values of 1.1 microM and 35 microM, respectively. The rises in cytosolic sodium ([Na+]i) and [Ca2+]i induced by the Na+ channel activator veratridine were also inhibited by amitriptyline with IC50 values of 7 microM and 30 microM, respectively. These results suggest that amitriptyline at micromolar concentrations inhibits both voltage-sensitive calcium (VSCCs) and sodium channels (VSSCs). Furthermore, submicromolar concentrations of amitriptyline significantly inhibited DMPP-induced [3H]NE secretion and [Ca2+]i rise, but not veratridine- or 70 mM K+-induced responses, suggesting that nicotinic acetylcholine receptors (nAChR) as well as VSCCs and VSSCs can be targeted by amitriptyline. DMPP-induced [Na+]i rise was much more sensitive to amitriptyline than the veratridine-induced rise, suggesting that the influx of Na+ and Ca2+, through the nAChR itself is blocked by amitriptyline. Receptor binding competition analysis showed that binding of [3H]nicotine to chromaffin cells was significantly affected by amitriptyline at submicromolar concentrations. The data suggest that amitriptyline inhibits catecholamine secretion by blocking nAChR, VSSC, and VSCC.

Adrenal Glands↗

PubMed1998

Implementation recommendations for making health care facilities latex safe.

The problem of latex allergy is not limited to health care workers who provide direct patient care. Individuals in environmental services, dietary, engineering, and medical records departments have the potential for sensitization. Due to the significant liability that may arise from a latex-induced anaphylaxis or death, it is no longer prudent for health care facilities to ignore the problem. This article proposes practical recommendations for implementation of an institution wide latex-safe environment in health care facilities.

Dermatitis, Contact↗

PubMed1998

Diagnostic evaluation of type I latex allergy.

BACKGROUND: Latex hypersensitivity affects a significant number of health care workers. No universally accepted method for the diagnosis of latex allergy is currently available in the United States. OBJECTIVE: Determine the accuracy of clinical assessment in predicting type I latex allergy, and compare the ability of various latex skin test preparations and in vitro assays in confirming the diagnosis of latex allergy. METHODS: Subjects were classified into "history positive," "history ambiguous," or "history negative" based on reports of clinical symptoms. Skin prick tests were performed with ammoniated latex and glove extracts. Sera were analyzed for latex-specific IgE using the Pharmacia CAP and DPC AlaSTAT assays. RESULTS: A total of 207 subjects had histories taken, skin testing, and blood drawn. Out of 49 type I latex-allergy "history positive," 42 (86%) were skin test positive, and 24 (49%) were serum positive. Fifty-nine subjects were latex allergy "history ambiguous." In this group, skin testing showed 19 (32%) positives, and latex-specific IgE were detected in 10 (17%). Out of 99 latex "history negative," 9 (9%) were skin test positive, and 11 (11%) were positive for latex-specific IgE. Out of the 61 subjects with IgE symptoms following latex exposure who were skin test positive, a positive in vitro assay was found in 32 (52%). CONCLUSIONS: Skin testing is more likely to confirm a positive latex allergy history. Use of raw ammoniated and glove skin testing preparation sources combined adds to the diagnostic sensitivity. AlaSTAT and CAP correlate well with each other and have good negative predictive value, but lack the sensitivity of skin testing. Use of AlaSTAT and CAP assays combined raises the diagnostic sensitivity as compared to using one in vitro test alone.

Allergens↗

PubMed1998

Inhibition of voltage-sensitive calcium channels by the A2A adenosine receptor in PC12 cells.

The role of the A2A adenosine receptor in regulating voltage-sensitive calcium channels (VSCCs) was investigated in PC12 cells. Ca2+ influx induced by membrane depolarization with 70 mM K+ could be inhibited with CGS21680, an A2A receptor-specific agonist. Both L- and N-type VSCCs were inhibited by CGS21680 treatment. Effects of adenosine receptor agonists and antagonists indicate that the typical A2A receptor mediates inhibition of VSCCs. Cholera toxin (CTX) treatment for 24 h completely eliminated the CGS21680 potency. Similar inhibitory effects on VSCCs were obtained by membrane-permeable activators of protein kinase A (PKA). These effects were blocked by Rp-adenosine-3',5'-cyclic monophosphothioate, a PKA inhibitor. The data suggest that activation of the A2A receptor leads to inhibition of VSCCs via a CTX-sensitive G protein and PKA. ATP pretreatment caused a reduction in subsequent rise in cytosolic free Ca2+ concentration induced by 70 mM K+, presumably by inactivation of VSCCs. Simultaneous treatment with ATP and CGS21680 produced significantly greater inhibition of VSCCs than treatment with CGS21680 or ATP alone. Furthermore, the CGS21680-induced inhibition of VSCCs was not affected by the presence of reactive blue 2. CGS21680 still significantly inhibited ATP-evoked Ca2+ influx without VSCC activity after cobalt or 70 mM K+ pretreatment. These data suggest that the A2A receptor-sensitive VSCCs differ from those activated by ATP treatment. Although A2A receptors induce inhibition of VSCCs as well as ATP-induced Ca2+ influx, the two inhibitory effects are clearly distinct from each other.

Adenosine↗

PubMed1998

Pulmonary nodules: CT-guided contrast material localization for thoracoscopic resection.

Fifteen patients underwent computed tomography (CT)-guided contrast material localization of pulmonary nodules, with barium and indigo carmine stain used in five patients, iodized oil and indigo carmine stain in five, and water-soluble contrast material and indigo carmine stain in five before fluoroscopy-assisted thoracoscopic resection. Contrast material localization was successful in all cases, and the surgeon confirmed accurate localization, CT-guided contrast material localization is simple and useful for thoracoscopic resection.

Adult↗

PubMed1997

Feedback regulation of ATP-induced Ca2+ signaling in HL-60 cells is mediated by protein kinase A- and C-mediated changes in capacitative Ca2+ entry.

Extracellular ATP increases intracellular Ca2+ ([Ca2+]i) in HL-60 cells. When cells are stimulated with supramaximal concentrations of ATP, although the initial [Ca2+]i increase is similar over a range of 30, 100, and 300 microM ATP, the rate of the return to basal [Ca2+]i level is faster in cells treated with higher concentrations of ATP. This probably results from differences in Ca2+ influx rather than Ca2+ release, since the influx of the unidirectional Ca2+ surrogates Ba2+ and Mn2+ also exhibit similar responses. Furthermore, while 300 microM ATP had an inhibitory effect on the thapsigargin-induced capacitative Ca2+ entry, 30 microM ATP potentiated the response. However, the inhibitory action of 300 microM ATP was blocked by protein kinase C (PKC) inhibitors, such as GF 109203X and chelerythrine, and the potentiating action of 30 microM ATP was blocked by protein kinase A (PKA) inhibitors H89 and Rp-cAMPS. The PKC inhibitors also slowed the decay rate of the Ca2+ response induced by 300 microM ATP, and the PKA inhibitors increased it when induced by 30 microM ATP. In the measurements of PKA and PKC activity, 30 microM ATP activates only PKA, while 300 microM ATP activates both kinases. Taken together, these data suggest that the changes in the ATP-induced Ca2+ response result from differential modulation of ATP-induced capacitative Ca2+ entry by PKC and PKA in HL-60 cells.

Adenosine Triphosphate↗

PubMed1997

Histamine inhibits ATP-induced [Ca2+]i rise through the activation of protein kinase A in HL-60 cells.

We investigated the cross-talk between the histamine and ATP receptors in HL-60 human promyelocytes. While both histamine and extracellular ATP increase intracellular Ca2+ concentration ([Ca2+]i) we found that histamine treatment causes a decrease in the subsequent ATP-induced Ca2+ release from intracellular stores and Ca2+ influx from extracellular space. In addition, histamine also inhibited the subsequent ATP-induced inositol 1.4,5-trisphosphate (IP3) generation in a manner comparable to the Ca2+ release. However, histamine did not inhibit thapsigargin-induced Ca2+ release and influx, thus indicating that histamine does not directly inhibit the Ca2+ release-activated channel (CRAC). Ca2+ elevation induced by 2'- and 3'-O-(4-benzoylbenzoyl) ATP (BzATP), which does not produce IP3, was also inhibited by treatment with histamine, suggesting the presence of ATP-gated channels that are regulated by histamine. Treatment with dibutyryl cAMP or 8-bromo-cAMP inhibited the subsequent ATP-induced response similar to histamine. Moreover, the incubation of cells with N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H89), a protein kinase A inhibitor abolished histamine's inhibitory effect on the ATP-induced [Ca2+]i rise and IP3 formation. These results suggest that histamine inhibits both ATP-induced IP3 production and ATP-activated channel opening, through protein kinase A activation.

Adenosine Triphosphate↗

PubMed1997

A peptide with unique receptor specificity: stimulation of phosphoinositide hydrolysis and induction of superoxide generation in human neutrophils.

Previously, we identified peptides that stimulate phosphoinositide hydrolysis in several leukocyte cell lines from mixtures of random hexapeptide sequences. Moreover, the peptides activate phospholipase C via a pertussis toxin-sensitive G protein-coupled receptor. We now investigate the structure-activity relationship of the peptides with the goal of improving the activity of the peptides, as well as the biologic function of the peptides. Substitution of the L-methionine at the C terminus of peptides with D-methionine markedly increased the effectiveness of the peptides. The half-maximal effective concentrations of MKYMPm-NH2 and WKYMVm-NH2 for stimulation of phosphoinositide hydrolysis in U266 cells were 30 and 0.5 nM, respectively. By BIAcore analysis we confirmed the existence of a receptor for WKYMVm-NH2. Furthermore, the intracellular calcium concentration increase induced by WKYMVm-NH2 was not inhibited by several chemoattractants (FMLP, IL-8, platelet-activating factor, C5a, granulocyte-macrophage CSF, and granulocyte CSF) suggests that WKYMVm-NH2 has a unique cell surface receptor on leukocytes. WKYMVm-NH2 stimulated the phosphoinositide hydrolysis in U937, HL60, and U266 cells, as well as in human neutrophils. Moreover, WKYMVm-NH2 is more effective than FMLP in the production of superoxide in human neutrophils. The data suggest that WKYMVm-NH2 may have the ability to activate the microbicidal functions of human neutrophils.

Amino Acids↗

PubMed1997

Extracellular ATP-stimulated increase of cytosolic cAMP in HL-60 cells.

Extracellular ATP increases intracellular Ca2+ concentration ([Ca2+]i) through activation of P2U purinoceptors in HL-60 cells. We found that extracellular ATP also increased the intracellular cAMP level in undifferentiated HL-60 cells. ATP and the hydrolysis-resistant ATP analogue adenosine 5'-O-(3-thiotriphosphate) triggered cAMP production in a concentration-dependent manner. The effects of ATP analogues on the [Ca2+]i elevation was distinguished from their effects on cAMP generation. Reactive Blue 2, the antagonist of P2 purinoceptors, inhibited ATP-induced cAMP generation in a concentration-dependent manner without inhibiting Ca2+ mobilization. The results suggest that a distinct P2 purinoceptor, one different from P2U, is linked to adenylyl cyclase in HL-60 cells.

Adenosine Triphosphate↗

PubMed1997

Stimulation of human DBH gene expression by prostaglandin E2 in human neuroblastoma SK-N-BE(2)C cells.

Prostaglandin E2 (PGE2) enhances transcription of the human dopamine beta-hydroxylase (DBH) gene in human neuroblastoma SK-N-BE(2)C cells. To identify a PGE2-responsive cis-acting element in the human DBH gene, serial deletion constructs of the human DBH 5'-upstream region fused to the chloramphenicol acetyltransferase (CAT) reporter gene were transiently transfected into SK-N-BE(2)C cells. Treatment of the transformed cells with PGE2 increased CAT expression two- to threefold in all constructs except where the promoter region was shortened beyond position -114 bp. There are several cis-regulatory elements in the region between -262 and -114 bp from the transcription initiation site that include a cyclic AMP response element (CRE) and a putative AP1 sequence. We presupposed that the CRE and AP1 might be candidates for PGE2 stimulation, and therefore, used site-directed mutagenesis to change the CRE and AP1 motives and test which of the two elements mediated the transcriptional enhancement. Only a specific mutation within the CRE sequence abolished the PGE2 effect. In addition, cotransfection with an expression vector expressing PKA inhibitor resulted in the specific blockage of the PGE2 effect on DBH gene expression. Northern blot analysis revealed that the increase in DBH gene transcription caused by PGE2 results in elevated DBH mRNA levels. Gel-retardation and competition assays confirmed that the binding of nuclear factors to the CRE site is sequence specific. Our data, therefore, indicate that PGE2 enhances the transcription of the human DBH gene. The effect is mediated by the CRE motif through activation of PKA.

Cyclic AMP Response Element-Binding Protein↗

PubMed1997

Outcome of pediatric patients with severe brain injury in Korea: a comparison with reports in the west.

There have been relatively wide variations in the results of studies examining the outcomes of severe brain injury in children. Among the reasons for these variations in outcome, prehospital care can be considered as one of the factors. In Korea, major hospitals use an aggressive and sophisticated management policy very similar to that practiced in the West. However, effective prehospital management, such as emergency care at the scene of injury and during transport by paramedics, have not yet been established. In order to evaluate the influence of prehospital care on the outcome in severely brain-injured children, we report the outcome recorded in 73 pediatric patients treated in our hospital following severe brain injury and compare these results with those reported from centers in the western community, where well-trained paramedic care and an excellent transfer system are in operation. The overall mortality rate in our patients was 23%; 41% had a good recovery, 22% moderate disability, and 12% severe disability, and 1% remained in a vegetative state. In conclusion, we would like to suggest that prehospital care does not remarkably influence mortality rates in severely brain-injured children.

Adolescent↗

PubMed1997

Novel anti-calcification treatment of biological tissues by grafting of sulphonated poly(ethylene oxide).

Biological porcine tissue was modified by the direct coupling of sulphonated poly(ethylene oxide) (PEO-SO3) containing amino acid end groups after glutaraldehyde fixation. The calcification of the modified tissue [bioprosthetic tissue (BT)-PEO-SO3] and control (BT control) was investigated by in vivo rate subdermal, canine aorta-illiac shunt and right ventricle-pulmonary artery shunt implantation models. Less calcium deposition of BT-PEO-SP3 than of BT control was observed in in vivo tests. Such a reduced calcification of BT-PEO-SO3 can be explained by decreases of residual glutaraldehyde groups, a space filling effect and, therefore, improved biostability and synergistic blood-compatible effects of PEO and SO3 groups after the covalent binding of PEO-SO3 to tissue. This simple method can be a useful anti-calcification treatment for implantable tissue valves.

Animals↗

PubMed1997

Stimulation of the A2A adenosine receptor increases expression of the tyrosine hydroxylase gene.

PC12 cells are known to express A2A adenosine receptors that are linked to adenylyl cyclase. We investigated the role played by A2A adenosine receptors in the expression of the rat tyrosine hydroxylase (TH) gene in PC12 cells. The A2A selective adenosine receptor agonist 2-(p-2-carboxyethyl)phenylethylamino)-5'-N-ethylcarboxyamidoade nosine (CGS21680) caused TH mRNA levels to increase to more than twice the level of the untreated control. Transient transfection analysis demonstrated that the transcription of the TH gene was markedly enhanced upon treatment with CGS21680. The adenosine receptor-mediated TH gene expression was confirmed by the inhibitory effects that adenosine receptor antagonists had on the CGS21680 response. Mutational analysis of the 5' upstream region of the TH gene revealed that the cAMP response element (CRE) at -45 to -38 bp was responsible for the CGS21680 effect. Gel mobility shift assays revealed that six CRE-specific DNA-protein complexes were formed, and the amounts of three of them were significantly increased by treatment with CGS21680. Co-transfection with an expression vector containing protein kinase A (PKA) inhibitor markedly decreased the CGS21680 effect. The results suggest that stimulation of the A2A adenosine receptor leads to an elevated expression of the TH gene by changing the binding pattern of DNA binding proteins that interact with CRE through activation of protein kinase A.

Adenosine↗

PubMed1997

A protein kinase C-activating phorbol ester enhances transcription of the human DBH gene through a cyclic AMP response element in SK-N-BE(2)C cells.

Protein kinase C (PKC) activation after treatment of human neuroblastoma SK-N-BE(2)C cells with phorbol 12-myristate 13-acetate (PMA) was found to enhance transcription of the human dopamine beta-hydroxylase (DBH) in those cells. To identify which cis-acting element is responsive to the PMA treatment during DBH gene expression, we employed transient transfection assays with serially deleted constructs of the human DBH gene's 5' upstream region fused to the chloramphenicol acetyltransferase (CAT) gene. Treatment of transfected cells with PMA resulted in an approximate threefold increase in CAT expression for all deletion constructs ranging from -978 bp to -262 bp, while the enhancement did not occur with a construct shortened to -114 bp. The region between -262 and -114 bp from the initiation site of transcription contains several cis-regulatory elements including a cyclic AMP response element (CRE) and putative AP1 and YY1 sequences. Site-directed mutagenesis of those cis-acting elements were performed to identify which of the elements mediated the PMA-induced transcriptional enhancement. Substitution of bases in the putative AP1 site containing in part a putative YY1 sequence did not effect the PMA inducibility. However, specific mutations in the CRE sequence abolished the PMA-inducible effect. Changing the CRE sequence into an authentic AP1 sequence (TGACGTCC --> TGACTCA) did not affect the PMA inducibility, suggesting that AP1 factors might interact with the new AP1 site upon PKC activation. A specific PKC inhibitor, GF109203X, completely inhibited the stimulatory effect of PMA on the expression of the human DBH gene. PMA induced an increase in the DBH mRNA level as detected by Northern blot analysis. Gel retardation showed that the binding of nuclear factors to CRE, putative YY1, and AP1 was sequence specific. Our data suggest that the enhancement of the human DBH gene expression by PMA treatment is mediated by the CRE motif in the 5' upstream region of the gene, and occurs via a PKC-dependent pathway.

Base Sequence↗

PubMed1997

Treatment of external urethral sphincter hypertonicity by pudendal nerve block using phenol solution in patients with spinal cord injury.

We report our experience utilizing the technique of phenol block of the pudendal nerve in the treatment of voiding dysfunction due to hypertonicity of the external urethral sphincter. We have performed 13 pudendal nerve blocks using a 7% phenol solution in seven patients with spinal cord injury who could not obtain relaxation of the external urethral sphincter with a large postvoid urine residual (150 ml to 600 ml) despite large doses of antispasticity drugs and intermittent catheterisations over three weeks. These drugs were discontinued at least 48 hours before this procedure. The efficacy of the pudendal nerve block could also be tested by the ease of facilitating micturition during or just after the block and measuring the amount of postvoid residual urine and intravesical leak pressure. A pudendal nerve block was produced by injecting a 7% phenol solution medial to the ischial tuberosity having specifically localized the nerve by electrical stimulation. This procedure improved the voiding pattern dramatically, leading to a full stream of urine and a remarkable decrease of postvoid residual volume and intravesical leak pressure. The mean difference of the postvoid residual volume and the intravesical leak pressure before and after pudendal nerve block was 255.7 ml and 57.5 cmH2O, respectively. We conclude that pudendal nerve block with a phenol solution as a treatment of external urethral sphincter hypertonicity was effective, easy to perform, and had no complication. This treatment should be considered as a possible alternative to more invasive surgical procedures.

Adult↗