Biomedical subjects

H L Kim

Publications and source records attributed to H L Kim.

At least 55 records · Page 3Linked to original sources

PubMed1997

Chromosomal localization and neural distribution of voltage dependent calcium channel beta 3 subunit gene.

Voltage dependent calcium channel (VDCC) mediates the influx of free calcium ions that acts as a signal transducer. The beta 3 subunit of the VDCC regulates the activation (opening) and inactivation (closing) kinetics through phosphorylation/dephosphorylation. We isolated a genomic clone of the human VDCC beta 3 subunit from a human genomic DNA library using VDCC beta 3 cDNA as a probe. We localized VDCC beta 3 with this genomic DNA on the chromosome by fluorescent in situ hybridization, and the distribution of VDCC beta 3 in the nervous system was investigated in rats by in situ hybridization histochemistry with rat VDCC beta 3 cDNA. The gene for the VDCC beta 3 was specifically localized on human chromosome 12q13. The mRNA for the VDCC beta 3 was predominantly expressed in the nervous system. In the brain, a strong expression of VDCC beta 3 mRNA was found in the medial habenular nucleus, a high level of expression was observed in the olfactory bulb and cerebellum, and a relatively high level of VDCC beta 3 mRNA was localized in the cerebral cortex, caudate-putamen and hippocampal formation. Interestingly, this distribution pattern is very similar to that of the rbE-II, mid-low VDCC 1 subunit, and it is suspected that VDCC beta 3 and rbE-II may function together as a pair.

Animals↗

PubMed1996

Accumulation of gossypol enantiomers in ovine tissues.

Tissue residue levels of gossypol enantiomers in cottonseed-fed and lethally intoxicated lambs were determined by the high-performance liquid chromatography-ultraviolet detection method. Gossypol was derivatized with (+)-2-amino-1-propanol and separated with a reversed-phase C18 column and the elution of analytes was monitored at 254 nm. The highest residue level was found in the liver tissue (318-416 ng total gossypol/mg dry tissue), and the residue of (-)-gossypol was higher than (+)-gossypol in the heart, muscle and spleen. The detection limit was 2 ng, and the detector response of gossypol-amine adducts was linear between 2 and 100 ng enantiomers.

Animal Feed↗

PubMed1995

Isolation of brefeldin A.

1. A chromatographic method for the isolation of brefeldin A (BFA) from the culture medium of Penicillium brefeldianis has been developed. BFA is adsorbed on a reversed-phase (C18) silica, desorbed by methanol, and the crystalline BFA precipitated from the concentrated aqueous solution. The yield of crystalline BFA is 121 mg/l of culture medium from a sample containing 204 mg/l determined by analytical HPLC. 2. The detection limit of BFA is 50 ng by analytical HPLC and BFA in the mother liquor of crystallization is recovered by preparative HPLC.

Anti-Bacterial Agents↗

PubMed1994

Electroconvulsive shock reduces inositol 1,4,5-trisphosphate 3-kinase mRNA expression in rat dentate gyrus.

We investigated the expression of inositol 1,4,5-trisphosphate (InsP3) 3-kinase mRNA after a single electroconvulsive shock (ECS) with in situ hybridization histochemistry in rat brain. At 6 h after ECS, the expression was markedly decreased in the dentate gyrus, and the decrease was maintained until 9 h with a slight recovery. The InsP3 3-kinase mRNA content returned to basal levels after 12 h. We could not detect any apparent changes in the expression of InsP3 3-kinase mRNA in the CA1-CA3 areas of hippocampus, the striatum, and the cerebral cortex at any time point examined. In the temporal pattern, the reduction of the expression in the dentate gyrus was preceded by the induction of c-fos after ECS. These observations suggest that the InsP3 3-kinase might be one of the genes whose expression can be altered by ECS.

Animals↗

PubMed1994

Calcium mass in human aortas from autopsy.

We used a single-energy x-ray method and an image processing system to measure the amount of calcium salts deposited in 60 human aortas (41 male and 19 female) of ages 15-88 y. The aortas were removed at autopsy, slit lengthwise and preserved in formalin. The aortas were x-rayed while flat, together with a calibration block containing known amounts of CaHPO4. We determined the amount of calcium salt, referenced to CaHPO4, from the x-ray film with a personal computer using a frame-grabbing board. There was less calcium in the thoracic than the abdominal aorta both in males and females and those of ages less than 50 y. The coefficient of correlation for abdominal aortic calcium mass versus age in 19 females was 0.557 and in 41 males was 0.321. The higher correlation of mass with age for females may be related to differences in calcium metabolism between sexes.

Adolescent↗

PubMed1992

Rat brain expresses an alternatively spliced form of the dihydropyridine-sensitive L-type calcium channel alpha 2 subunit.

We have cloned and sequenced a cDNA (rB-alpha 2) encoding an alpha 2 subunit of the voltage-sensitive L-type calcium channel (dihydropyridine receptor) of rat brain. The cDNA (3823 base pairs) encodes a protein of 1091 amino acids with a Mr of 123,822. The deduced amino acid sequence of rB-alpha 2 cDNA is highly similar (95% amino acid identity) to that of rabbit skeletal muscle alpha 2 subunit. The rB-alpha 2 protein is distinct from the previously cloned skeletal muscle alpha 2-subunit protein [Ellis, S. B., Williams, M. E., Ways, N. R., Brenner, R., Sharp, A. H., Leung, A. T., Campbell, K. P., McKenna, E., Koch, W., Hui, A., Schwartz, A. & Harpold, M. M. (1988) Science 241, 1661-1664] because it contains an insertion of 7 amino acid residues and a deletion of a 19-amino acid segment between putative transmembrane domains 1 and 2. We show that the rB-alpha 2 and skeletal muscle alpha 2-subunit transcripts are the variants produced by alternative splicing of the primary transcript and that they are differentially expressed in brain and skeletal muscle, respectively.

Amino Acid Sequence↗

PubMed1992

Expression of dihydropyridine-sensitive brain calcium channels in the rat central nervous system.

We have localized dihydropyridine (DHP-sensitive calcium channels in rat brain by in situ hybridization and immunohistochemistry. The mRNA for the dihydropyridine-sensitive calcium channel alpha 1 subunit (DHPR-B) is prominently localized in neuronal cells in the olfactory bulb, dentate gyrus, hippocampus, arcuate nucleus, paraventricular nucleus, ventromedial nucleus, cerebral cortex, superior colliculus and the cerebellar Purkinje cell layer. Strong expression of DHPR-B mRNA was also found in the pituitary and pineal glands. DHP-sensitive calcium channel alpha 1 subunit distribution has also been examined immunohistochemically with polyclonal antibodies raised against synthetic peptides specific for the DHPR-B alpha 1 subunit protein. The results from immunohistochemistry were in good agreement with those from in situ hybridization. Thus, regional distribution and localization of DHPR-B mRNA and alpha 1 subunit protein in rat brain suggest that this type of DHP-sensitive brain calcium channel may play an important role in excitation-secretion coupling functions in the neuroendocrine system.

Amino Acid Sequence↗

PubMed1992

Isolation of sesbanimide from the seed of Sesbania vesicaria.

1. The HPLC separation of a water-soluble toxic fraction isolated from the seed of Sesbania vesicaria provided a potent antileukemic compound which was identified as sesbanimide (or sesbanimide A). The identity was established by comparison of the proton magnetic resonance spectra of the isolated sesbanimide and the authentic sample. 2. The IC50 value determined by the activity against the growth of murine leukemia (L1210) cells in vitro was 0.8 ng/ml.

Alkaloids↗

PubMed1992

The gene for the dihydropyridine-sensitive calcium channel alpha 2 subunit (CCHL2A) maps to the proximal region of mouse chromosome 5.

A rat brain cDNA probe for the gene encoding the alpha 2 subunit of the dihydropyridine-sensitive L-type calcium channel was used as a hybridization probe for the Southern blot analysis of Chinese hamster x mouse somatic cell hybrids and the progeny of an intersubspecies backcross. This gene, termed Cchl2a, was mapped near the centromeric end of the Chromosome 5 linkage group with gene order: centromere-Pgy-1-Cchl2a-Il-6-Pgm-1.

Animals↗

PubMed1992

The gene for the alpha 1 subunit of the skeletal muscle dihydropyridine-sensitive calcium channel (Cchl1a3) maps to mouse chromosome 1.

Cchl1a3 encodes the dihydropyridine-sensitive calcium channel alpha 1 subunit isoform predominantly expressed in skeletal muscle. mdg (muscular dysgenesis) has previously been implicated as a mutant allele of this gene. Hybridization of a rat brain cDNA probe for Cchl1a3 to Southern blots of DNAs from a panel of Chinese hamster x mouse somatic cell hybrids suggested that this gene maps to mouse Chromosome 1. Analysis of the progeny of an inbred strain cross-positioned Cchl1a3 1.3 cM proximal to the Pep-3 locus on Chr 1.

Animals↗

PubMed1992

Ovine urinary metabolites of ethoxyquin.

Metabolites of ethoxyquin (EQ, 1,2-dihydro-6-ethoxy-2,2,4-trimethylquinoline) in the urine of sheep and rats were separated and identified by gas chromatography-mass spectrometry (GC-MS). Sheep were given diets containing EQ or EQ.HCl (0.5% of total diet) and urine samples were collected for the first 24 h and for another 24-h period after 12 d of feeding. Rats were given EQ/corn oil (0.08 g EQ/d/rat) orally for 7 d and urine samples were collected at ambient temperature for a 24-h period following 6 d of dosing. The urine samples were extracted with ethyl acetate at pH 5, and the concentrated extracts were analyzed by GC-MS. Ethoxyquin was identified in all sheep urine samples collected during the first 24 h of feeding, and EQ and hydroxylated EQ were identified in all urine samples collected after 12 d of feeding. In contrast, EQ, hydroxylated EQ, and dihydroxylated EQ were identified in urine collected from rats fed EQ for 7 d.

Administration, Oral↗

PubMed1991

Effects of hydroxylated polychlorinated biphenyls on mouse liver mitochondrial oxidative phosphorylation.

The effects of three tetrachlorobiphenylols [2',3',4',5'-tetrachloro-2-biphenylol (1); 2',3',4',5'-tetrachloro-4- biphenylol (2); and 2',3',4',5'-tetrachloro-3-biphenylol (3)]; three monochlorobiphenylols [5-chloro-2-biphenylol (5), 3-chloro-2-biphenylol (6); and 2-chloro-4-biphenylol (7)] and a tetrachlorobiphenyldiol [3,3',5,5'-tetrachloro-4,4'-biphenyldiol (4) on respiration, adenosine triphosphatase (ATPase) activity, and swelling in isolated mouse liver mitochondria have been investigated. Tetrachlorobiphenylols (1-3) and the tetrachlorobiphenyldiol (4) inhibited state-3 respiration in a concentration-dependent manner with succinate as substrate (flavin adenine dinucleotide [FAD]-linked) and the tetrachlorobiphenyldiol (4) caused a more pronounced inhibitory effect on state-3 respiration than the other congeners. The monochlorobiphenylols 5-7 were less active as inhibitors of state-3 mitochondrial respiration and significant effects were observed only at higher concentration (greater than or equal to 0.4 microM). However, in the presence of the nicotinamide adenine dinucleotide (NAD)-linked substrates (glutamate plus malate), hydroxylated PCBs (1-7) significantly inhibited mitochondrial state-3 respiration in a concentration-dependent manner. Compounds 5, 6, and 7 uncoupled mitochondrial oxidative phosphorylation only in the presence of FAD-linked substrate as evidenced by increased oxygen consumption during state-4 respiratory transition, stimulating ATPase activity, releasing oligomycin-inhibited respiration, and inducing mitochondrial swelling (5, 6, and 7). Tetrachlorobiphenylols 1, 2, and 3 had no effect on mitochondrial ATPase activity while the tetrachlorobiphenyldiol, 4, decreased the enzyme activity. The possible inhibitory site of electron transport by these compounds and their toxicologic significance is discussed.

Adenosine Triphosphatases↗

PubMed1991

A brain L-type calcium channel alpha 1 subunit gene (CCHL1A2) maps to mouse chromosome 14 and human chromosome 3.

A rat brain cDNA probe was used to localize a gene encoding the alpha 1 subunit of neuronal dihydropyridine-sensitive L-type calcium channels in the mouse and human genomes. Hybridization of the probe to Southern blots made with DNAs from a Chinese hamster x mouse somatic cell hybrid panel indicated that this gene maps to mouse chromosome 14 (Chr 14). Southern blot analysis of an intersubspecies cross demonstrated that the calcium channel alpha 1 subunit gene, termed Cchl1a2, can be positioned 7.5 cM proximal to Np-1. Similarly, segregation among human X rodent somatic cell hybrids indicated that CCHL1A2 maps to human chromosome 3. These assignments are consistent with a region of linkage homology between human chromosome 3p and a proximal region of mouse Chr 14.

Animals↗

PubMed1991

Accumulation of ethoxyquin in the tissue.

Ethoxyquin (EQ) residue levels in the mouse tissue were determined by the HPLC-fluorometric detection method. Mice were given powdered feed containing 0, 0.125, and 0.5% EQ HCl and the EQ residue levels in liver, kidney, lung, and brain tissues were determined after 2, 4, 6, 10, and 14 wk (4 mice/group). The tissue samples were homogenized in 10 volumes (w/v) of acetonitrile-water (7:3, v/v), centrifuged, and the supernatants were stored in a freezer for 2-3 h or until the two layers separated; then the clear upper layers were analyzed. The mean EQ residue levels in the tissue ranged 0.84-4.58 micrograms EQ/g liver and 0.11-0.92 micrograms EQ/g brain. The relative weight of the liver (5.21-7.07% body weight) and the hepatic glutathione level (5.99-7.83 microM GSH/g tissue) of mice that received EQ were significantly higher than those of the controls (4.67-5.05% body weight and 4.30-5.78 microM GSH/g tissue, respectively). The mean hepatic mitochondrial glutathione level of the higher EQ feeding group, following dietary administration of EQ for 14 wk, was approximately twofold (1.68 nM GSH/mg protein) of both the control and the lower EQ feeding groups (0.83 and 0.74 nM GSH/mg protein, respectively).

Administration, Oral↗

PubMed1989

Effects of sesquiterpene lactones on mitochondrial oxidative phosphorylation.

1. The toxic plant sesquiterpene lactones, helenalin, hymenoxon, mexicanin-E, tenulin, dihydrogriesenin, and psilotropin which were isolated from Helenium, Hymenoxys, and Geigeria spp markedly inhibited "state 3" respiration in mouse hepatic mitochondria. With the exception of dihydrogriesenin and psilotropin, all the other sesquiterpene lactones stimulated "state 4" respiration. 2. The sesquiterpene lactones also stimulated ATPase activity in the presence of Mg2+ ions and caused mitochondrial swelling in buffer solutions containing magnesium, sodium, ammonium and potassium chloride salts. 3. The number of alkylating sites present in a sesquiterpene lactone appears to be related to the inhibitory activity on mitochondrial oxidative phosphorylation, however, the structure-activity relationship of these lactones is not clear at present. 4. Mitochondria prepared from the liver of ethoxyquin hydrochloride-fed mice were less susceptible to sesquiterpene lactone-mediated inhibition of mitochondrial oxidative phosphorylation.

Adenosine Triphosphatases↗

PubMed1989

Induction of glutathione S-transferases in genetically inbred male mice by dietary ethoxyquin hydrochloride.

1. Constitutive and ethoxyquin hydrochloride (EQ-HCl)-induced hepatic glutathione (GSH) S-transferase, GSH reductase, and GSH peroxidase activities were determined in 5 strains of 8-10 week old inbred male mice. 2. The constitutive GSH S-transferase (GST) activity varied from 2.9 (SJL/JCR) to 8.9 (C57BL/6NCR) mumol product formed/min/mg protein and the corresponding values for the EQ-HCl-treated mice were in the range of 15.3-25.3 mumol product formed/min/mg protein. 3. EQ-HCl induced GST activity in all the strains examined and this contrasted to the induction activity of Aroclor 1254 which was strain-dependent. GST activity was induced 2.9-fold in Aroclor 1254-responsive (C57BL/6) and 2.8-fold in non-responsive (DBA/2) mice, respectively.

Animals↗

PubMed1989

Role of thiol agents in protecting against the toxicity of helenalin in tumor-bearing mice.

Helanalin, a sesquiterpene lactone antineoplastic agent, is toxic at therapeutic doses in murine tumors. The toxicity has been assumed to be correlated with the binding of the drug to cellular thiol groups. Studies were undertaken to increase the intracellular level of GSH in the liver, kidney and other tissues to eliminate the toxicity of helenalin in vivo. Combination of helenalin 8 mg/kg/day i.p.) with L-cysteine (100 mg/kg/day), beta-mercaptoethanolamine (20 mg/kg/day), 18-beta-glycyrrhetinic acid (15 mg/kg/day), or 4,4'-diaminodiphenylsulfone (10 mg/kg/day) afforded improvement in survival of mice bearing P-388 lymphocytic leukemia. However, other thiol-elevating agents, anti-oxidants, intracellular buffering agents, and cardiac treatment drugs were not effective. Hydrocortisone, Cortef, treatment with helenalin afforded improvement in life expectancy. Reduced glutathione (GSH) and non-protein sulfhydryl (NPS) levels were not reduced in the liver, kidney, or circulating red blood cells (rbc) by helenalin treatment. After three days treatment of mice with helenalin, GSH levels were reduced and NPS levels elevated in P-388 tumor cells. Administration of L-cysteine, beta-mercaptoethanolamine, 4,4'-diaminodiphenylsulfone, or 18-beta-glycyrrhetinic acid alone caused no alteration in liver GSH but elevated NPS levels; P388 cell GSH and NPS levels were lowered. Combination of any of these agents, after three days, with helenalin afforded increases in P-388 cell GSH and NPS levels. This data would suggest that helenalin toxicity is not related to the lowering of GSH or NPS levels in critical tissues of mice.

Animals↗

PubMed1989

[Effect of changing position from supine to standing upright on the circulation of young men and women].

This study investigated the effect of changing position from supine to standing upright on the circulation of young men and women. Healthy men and women ranging from age of 18 to 24 were examined. Two minutes before standing, the baseline heart rate and blood pressure were measured. Heart rate and blood pressure were recorded immediately and at every minute for 10 minutes after standing upright. Differences in heart rate and blood pressure between supine and standing upright position were evaluated. The results were summarized as follows: 1. Heart rate increased significantly immediately and at every minute for 10 minutes after standing upright. 2. Systolic blood pressure increased significantly immediately and at every minute for 4 minutes after standing upright. 3. Diastolic and mean blood pressure increased significantly immediately and at every minute for 10 minutes after standing upright. 4. Pulse pressure immediately and at every minute for 10 minutes after standing upright was significantly narrower than that of supine position. 5. There was no significant difference of heart rate between men and women after standing upright. 6. Systolic and diastolic blood pressure of men after standing upright was significantly greater than those of women. From these results, it may be concluded that heart rate, systolic, diastolic and mean blood pressure and pulse pressure increase after standing upright, and systolic and diastolic blood pressure in men is greater than those of women after standing upright.

Adult↗