Biomedical subjects

Y H Chung

Publications and source records attributed to Y H Chung.

At least 19 recordsLinked to original sources

PubMed2006

DRE-CALUX bioassay in comparison with HRGC/MS for measurement of toxic equivalence in environmental samples.

CALUX, Chemically Activated LUciferase gene eXpression bioassay, has proven valuable for screening for and assessing toxic equivalents of dioxin-like compounds, because it detects all AhR (arylhydrocarbon receptor) ligands in a variety of sample matrices. In this study, we tried to validate DRE (dioxin-response elements)-CALUX bioassay, which has been developed by cloning mouse cyp1a1 gene in front of luciferase reporter gene. We compared DRE-CALUX bioassay with high resolution gas chromatography/mass spectrometry (HRGC/MS) for assessing environmental samples from Korea. 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) dose response study showed high correlation (r2=0.89) between DRE-CALUX bioassay and EROD (ethoxyresorufin O-deethylase) bioassay, a commonly used bioassay method. The mean TEQ value of water samples was 0.57 pg-TEQ(HRGC/MS)/L and 4.97 pg-TEQ(CALUX)/L. For soil samples, HRGC/MS-TEQ values ranged from 0 to 47.18 pg-TEQ/g (dry) and correlated well (r2=0.98) with values obtained by CALUX-TEQ which ranged from 0.92 to 649.97 pg-TEQ/g (dry). The difference between the absolute TEQ values might be due to the presence of dioxin-like compounds without WHO-TEQ values rather than the difference between CALUX-REP and WHO-TEQ. Based on this study, we suggest that DRE-CALUX bioassay can serve as an alternative bioassay method for high-throughput analysis of large number of environmental samples.

Biological Assay↗

PubMed2006

Evaluation of subchronic inhalation toxicity of dimethyl disulfide in rats.

This study was carried out to investigate the potential subchronic inhalation toxicity of dimethyl disulfide (DMDS) via whole-body exposure in F344 rats. Groups of 10 rats of each sex were exposed to DMDS vapor by whole-body exposure at concentrations of 0, 5, 25, or 125 ppm for 6 h/day, 5 days/wk for 13 wk. All the rats were sacrificed at the end of treatment period. During the test period, clinical signs, mortality, body weights, food consumption, ophthalmoscopy, urinalysis, hematology, serum biochemistry, gross findings, organ weights, and histopathology were examined. At 25 ppm, a decrease in the body weight gain, food intake, aspartate aminotransferase (AST), alanine aminotransferase (ALT), and blood urea nitrogen (BUN) was observed in the males, but not in the females. However, at 125 ppm, a decrease in the body weight gain, food intake, and thymus weight and an increase in the weights of adrenal glands were observed in both genders. Serum biochemical investigations revealed a decrease in the AST, ALT, BUN, creatine phosphokinase (CPK), and triglyceride levels and an increase in the glucose level. In contrast, no treatment-related effects were observed in the 5 ppm group. The toxic potency of DMDS was slightly higher in males than that in females. In these experimental conditions, the target organ was not determined in rats. The no-observed-adverse-effect concentration (NOAEC) was found to be 5 ppm, 6 h/day for male rats and 25 ppm, 6 h/day for female rats.

Alanine Transaminase↗

PubMed2006

Effects of methionine and lysine on fermentation in vitro and in vivo, nutrient flow to the intestine, and milk production.

Three experiments were conducted to investigate the feasibility of using crystalline methionine and lysine as protein supplements for lactating Holstein cows. In the first experiment, Met (dl-methionine) and Lys (l-lysine-HCl) were added to diets used in continuous culture bioreactors to estimate optimal concentrations for use in subsequent in vivo experiments. The second experiment measured ruminal fermentation and nutrient flow to the small intestine when Met and Lys were top-dressed on diets fed to nonlactating cows. The third experiment measured lactation performance when Met and Lys were added to diets fed to late-lactation cows. Providing 0.29 and 2.27% of dry matter as Met and Lys, respectively, provided the largest improvement in fermentation in vitro and these concentrations were used in subsequent experiments. When Met and Lys were top-dressed on diets fed to nonlactating cows, no changes in total tract N digestion were observed. No changes in microbial protein production or ruminal fermentation were observed. Adding Met and Lys did not change production or efficiency of production of milk or milk components by late lactation cows. These data indicate that providing supplemental Met and Lys during late lactation does not significantly improve the protein status of the cow and therefore may not improve milk production.

Ammonia↗

PubMed2006

Identification of Salmonella enterica serovar Typhimurium using specific PCR primers obtained by comparative genomics in Salmonella serovars.

Salmonella enterica serovar Typhimurium is a major foodborne pathogen throughout the world. Until now, the specific target genes for the detection and identification of serovar Typhimurium have not been developed. To determine the specific probes for serovar Typhimurium, the genes of serovar Typhimurium LT2 that were expected to be unique were selected with the BLAST (Basic Local Alignment Search Tool) program within GenBank. The selected genes were compared with 11 genomic sequences of various Salmonella serovars by BLAST. Of these selected genes, 10 were expected to be specific to serovar Typhimurium and were not related to virulence factor genes of Salmonella pathogenicity island or to genes of the O and H antigens of Salmonella. Primers for the 10 selected genes were constructed, and PCRs were evaluated with various genomic DNAs of Salmonella and non-Salmonella strains for the specific identification of Salmonella serovar Typhimurium. Among all the primer sets for the 10 genes, STM4497 showed the highest degree of specificity to serovar Typhimurium. In this study, a specific primer set for Salmonella serovar Typhimurium was developed on the basis of the comparison of genomic sequences between Salmonella serovars and was validated with PCR. This method of comparative genomics to select target genes or sequences can be applied to the specific detection of microorganisms.

Base Sequence↗

PubMed2005

The presence of megamitochondria in the ellipsoid of photoreceptor inner segment of the zebrafish retina.

Although the megamitochondria (MM) were localized in various pathological conditions, normal retina of some mammalian species was reported to include MM for various physiological roles. However, it was not clearly confirmed whether the MM is present in the retina of lower vertebrate as well. In this study, we tried to show the presence of the MM in the zebrafish retina using electron microscopic technique. In all the photoreceptors including rods, cones and double cones of the zebrafish retina, MM were observed in the ellipsoid of inner segment. In the photoreceptor epllipsoid of the zebrafish retina, the mitochondria located in the central portion of the ellipsoid had a highly electron-dense matrix, which were accompanied by the mitochondria with electron-lucent matrix in the apical portion of the ellipsoid. The presence of MM was more clearly discernable in the rods, which were localized under the double cones. This finding is somewhat different from those observed in the previous studies because MM were localized in the inner segment of cones, but were not in those of rods in the case of mammalian retina. Although the exact physiological meaning for the presence of MM in some vertebrate species should be further studied, the present study could show that the MM in the ellipsoid of the retinal photoreceptors was not only restricted in some mammalian species.

Animals↗

PubMed2004

GATE: a simulation toolkit for PET and SPECT.

Monte Carlo simulation is an essential tool in emission tomography that can assist in the design of new medical imaging devices, the optimization of acquisition protocols and the development or assessment of image reconstruction algorithms and correction techniques. GATE, the Geant4 Application for Tomographic Emission, encapsulates the Geant4 libraries to achieve a modular, versatile, scripted simulation toolkit adapted to the field of nuclear medicine. In particular, GATE allows the description of time-dependent phenomena such as source or detector movement, and source decay kinetics. This feature makes it possible to simulate time curves under realistic acquisition conditions and to test dynamic reconstruction algorithms. This paper gives a detailed description of the design and development of GATE by the OpenGATE collaboration, whose continuing objective is to improve, document and validate GATE by simulating commercially available imaging systems for PET and SPECT. Large effort is also invested in the ability and the flexibility to model novel detection systems or systems still under design. A public release of GATE licensed under the GNU Lesser General Public License can be downloaded at http:/www-lphe.epfl.ch/GATE/. Two benchmarks developed for PET and SPECT to test the installation of GATE and to serve as a tutorial for the users are presented. Extensive validation of the GATE simulation platform has been started, comparing simulations and measurements on commercially available acquisition systems. References to those results are listed. The future prospects towards the gridification of GATE and its extension to other domains such as dosimetry are also discussed.

Computer Simulation↗

PubMed2004

Effects of zinc and sodium monensin on ruminal degradation of lysine-HCl and liquid 2-hydroxy-4-methylthiobutanoic acid.

Four nonlactating, mature, Holstein cows were fitted with ruminal cannula and used in a 4 x 4 Latin square-designed experiment to evaluate the impact of supplemental Zn and monensin on ruminal degradation of Lys and liquid 2-hydroxy-4-methylthiobutanoic acid (HMB). Cows were fed 4.54 kg (as fed) of alfalfa hay top-dressed with 4.54 kg (as fed) concentrate once daily. Concentrates were formulated to provide 0 or 500 mg/kg of Zn as ZnSO4 and 0 or 40 mg/kg of monensin in the total diet. Zinc supplementation provided approximately 22-fold greater dietary Zn than estimated by NRC requirements. On d 14 of each period, cows were dosed via the rumen cannula with 50 g of HMB and 100 g of Lys-HCl, and the concentrations of Lys and HMB were monitored every 0.5 h for 8 h. Supplemental Zn tended to decrease the proportion of acetate in ruminal fluid postfeeding and increased the proportion of propionate in ruminal fluid postfeeding. Supplemental Zn increased mean fluid passage rate from the rumen. Monensin decreased the proportion of acetate and increased the mean proportion of propionate in ruminal fluid, resulting in a decrease in the ratio of acetate to propionate. Monensin also increased the mean fluid passage rate from the rumen. Neither Zn nor monensin affected the apparent rate of ruminal disappearance of HMB or Lys. However, Zn and monensin interacted to alter the ruminal degradability of free Lys but not HMB. These data indicate that Zn and monensin may interact to alter ruminal degradability of free amino acids.

Acetates↗

PubMed2003

Independent association of HLA-DR and FCgamma receptor polymorphisms in Korean patients with systemic lupus erythematosus.

OBJECTIVES: To determine the distribution of HLA-DR type and FcgammaRIIa/IIIa polymorphisms, and to analyse the combined effects of these genes for susceptibility in Korean systemic lupus erythematosus (SLE) patients. METHODS: A total of 299 SLE patients meeting 1982 ACR criteria and 144 Korean disease-free controls were enrolled. Genotyping for the FcgammaRIIa 131 R/H and FcgammaRIIIa 176 F/V was performed by polymerase chain reaction (PCR) of genomic DNA using allele-specific primers. HLA-DRB1 typing was performed by the PCR-SSOP method. RESULTS: There was significant skewing in the distribution of the three FcgammaRIIa genotypes between the SLE patients and the controls [P = 0.002 for R/R131 vs R/H131 and H/H131, relative risk (RR) 2.6 (95% CI 1.3-5.2)], but not in FcgammaRIIIa genotypes. HLA-DRB1*15 allele was significantly more prevalent among SLE patients than the control population [P < 0.02, RR = 1.7 (1.1-2.6)]. HLA-DRB1 genotypes or allele frequencies of the SLE patients with nephritis did not differ significantly from those of the SLE patients without nephritis. We analysed the combined effects of the two candidate genes on SLE susceptibility. HLA-DRB1*15 allele was a significant predictor of SLE in individuals who were not homozygous for FcgammaRIIa-R/R131 [RR = 2.1 (1.2-3.7), P < 0.008], and the FcgammaRIIa-R/R131 genotype vice versa [RR = 5.3 (1.9-15.4), P < 0.001]. However, an additive or synergistic effect of both susceptible genes on relative risk for SLE was not evident. CONCLUSIONS: Our results suggest that FcgammaRIIa-R/R131 homozygote and HLA-DRB1*15 allele are independent risk factors in Korean SLE patients without additive or synergistic effects.

Adult↗

PubMed2003

Prevalence and antibiotic susceptibility of Salmonella isolated from foods in Korea from 1993 to 2001.

This study determined the prevalence of Salmonella in foods widely consumed in Korea from 1993 to 2001, along with antimicrobial susceptibility profiles of Salmonella isolates from these foods for 11 antibiotics. Overall, 41 Salmonella isolates, representing 15 serotypes, were obtained from 2.2% (29 of 1,334) of the samples examined, and most of the Salmonella isolates were recovered from broiler carcasses. The most common serotypes were Salmonella Enteritidis (29.3%), Salmonella Virginia (14.6%), and Salmonella Haart (12.2%). All isolates were screened for antibiotic resistance; 14.6% of the isolates were susceptible to all of the antibiotics, 4.9% were resistant to one antimicrobial agent, 14.6% were resistant to two antimicrobial agents, 22.0% were resistant to three antimicrobial agents, 39.0% were resistant to four antimicrobial agents, and 4.9% were resistant to five antimicrobial agents. Most of the isolates showed resistance or intermediate resistance to streptomycin, ampicillin, carbenicillin, and/or tetracycline.

Animals↗

PubMed2002

Immune evasion strategies of Kaposi's sarcoma-associated herpesvirus.

To establish lifelong infection in the presence of an active host immune system, herpesviruses have acquired an impressive array of immune modulatory mechanisms that contribute to their success as long-term parasites. Kaposi's sarcoma-associated herpesvirus (KSHV) is the most recently discovered human tumor virus and is associated with the pathogenesis of Kaposi's sarcoma, primary effusion lymphoma, and multicentric Castleman's disease. KSHV has acquired a battery of genes to assist in viral survival against the host immune response. These viral gene products target a variety of host immune surveillance mechanisms, including the cytokine-mediated immune response, apoptosis, natural killer (NK) cell killing and T cell-mediated responses. This review summarizes our understanding of the role of these viral proteins in the escape from host immune surveillance, which ultimately contributes to lifelong infection and pathogenesis of KSHV.

Animals↗

PubMed2002

Adult-to-adult living donor liver transplantation at the Asan Medical Center, Korea.

Between February 1997 and December 2001, 311 adult-to-adult living donor liver transplants (A-A LDLTs) were performed at the Asan Medical Center for patients above 20 years of age. Indications for A-A LDLT were: chronic hepatitis B (203), chronic hepatitis C (5), hepatocellular carcinoma (64), alcoholic cirrhosis (9), cryptogenic cirrhosis (4), secondary biliary cirrhosis (5), primary biliary cirrhosis (1), Wilson' s disease (2), autoimmune hepatitis (1), hepatic tuberculosis (1), cholangiocarcinoma (1), fulminant hepatic failure (14) and primary non-function of cadaveric liver graft (1). Of 311 A-A LDLTs, 36 were of medical high urgency, 20 were for acute and subacute hepatic failure, 15 were for hepato-renal syndrome and 1 was for primary non-function. Recipient age ranged from 27 to 64 years. Donor age ranged from 16 to 62 years. There was no donor mortality. Implanted liver grafts were categorized into seven types: 175 modified right lobe (MRL), 70 left lobe, 32 right lobe, 20 dual grafts, 10 left lobe plus caudate lobe, three extended right lobe and one posterior segment. In MRL, the tributaries of the middle hepatic vein were reconstructed by interpositioning a vein graft. Indication for dual graft implantation was the same as single graft A-A LDLT, and four of 20 were emergency cases. Of 20 dual grafts, 14 received two left lobes, four received a left lobe and a lateral segment, one received a right lobe and a left lobe and one received a lateral segment and a posterior segment. Graft volume ranged from 28% to 83% of the standard liver volume of the recipients. There were 33 (10.6%) in-hospital mortalities (< 4 months) among the 310 patients after 311 A-A LDLTs. Of the 36 patients receiving emergency transplants, 31 survived. These encouraging results justify the expansion of A-A LDLT in coping with increasing demands, even in urgent situations. We have aimed to introduce the establishment of the efficacy of A-A LDLT in various end-stage chronic and acute liver diseases, as well as new technical advances to overcome small graft-size syndrome by using dual-graft implantation and MRL, both of which were first developed in our department.

Adult↗

PubMed2002

Angiotensin-converting enzyme gene polymorphism and vascular manifestations in Korean patients with SLE.

Systemic lupus erythematosus (SLE) is an inflammatory multisystem disease of unknown etiology with immunologic aberrations. Many studies have shown that genetic and environmental factors are implicated in the development of SLE. Angiotensin-converting enzyme (ACE) affects various immune phenomena through the renin-angiotensin and kallikrein-kininogen systems by creating angiotensin II and inactivating bradykinin. We investigated the correlation between insertion/ deletion polymorphism of the ACE gene and the clinical manifestations of SLE, especially vascular involvement and lupus nephritis. Two-hundred and eleven Korean patients fulfilling the ACR criteria and 114 healthy subjects were enrolled. The ACE genotype was determined by polymerase chain reaction using genomic DNA from peripheral blood. The nephritis patients were classified by the WHO classification. In addition, the activity and chronicity index were used to assess the severity of renal involvement. We evaluated vascular involvement by the presence or absence of hypertension, Raynaud's phenomenon, livedo reticularis, antineutrophil cytoplasmic antibody and the SLICC/ACR Damage Index. The gene frequency of ACE gene polymorphism was as follows: II 39 vs 34%, ID 41 vs 50%, DD 20 vs 16% in SLE patients and controls, respectively. There was no difference in genotype frequency between both groups. There were no significant differences between the distribution of ACE gene genotypes and lupus nephritis and its related parameters, including WHO classification, activity index, chronicity index, renal dysfunction and amount of 24 h urinary protein. The ACE genotypes and alleles did not affect the presence of vascular manifestations evaluated, but the frequency of DD genotype was significantly low in SLE patients with Raynaud's phenomenon compared to those without Raynaud's phenomenon (P = 0.002 for ACE ID vs DD and II, OR 2.7, 95% CI 1.43-5.09; P=0.023 for ACE DD vs ID and II, OR 0.33, 95% CI 0.12-0.89). Also skewing from DD to II genotype was noted in patients with anti-Sm antibody compared to those without anti-Sm antibody (P = 0.025 for ACE DD vs ID and II, OR 0.21, 95% CI 0.05-0.93). The onset age of serositis was older in patients with the ID genotype than the others (ID= 34.5+/-10.8, II + DD = 25.6+/-10.2, P= 0.002). Also the onset age of malar rash was older in patients with II genotype than the others (II=26.7+/-8.4, ID+DD=21.3+/-9.0; P=0.021). The patients with I allele showed a significantly higher frequency of serositis (P = 0.022). Taken together, the I/D polymorphisms of ACE gene did not affect susceptibility of SLE, lupus nephritis and the vascular manifestations, including Raynaud's phenomenon, in Korean SLE patients, although the DD genotype was negatively associated with Raynaud's phenomenon among SLE patients. However, it would be valuable to evaluate the role of other genes potentially related to vascular events, such as endothelin, nitric oxide or angiotensin II receptor as well as ACE gene.

Adult↗

PubMed2001

Spatial and temporal distribution of pituitary adenylate cyclase activating polypeptide in gerbil global cerebral ischemia.

In the present study, we used immunohistochemistry to investigate the effects of transient global ischemia on pituitary adenylate cyclase activating polypeptide (PACAP) immunoreactivity in gerbil brain regions. PACAP immunoreactivity had significantly decreased in the pyramidal cells of CA1 subfield susceptible to ischemic insult at 1-4 days after transient global ischemia. On the contrary, PACAP immunoreactivity had not changed in the pyramidal cell bodies of more resistant CA3 subfield after ischemic injury. In the Purkinje cell layer, PACAP immunoreactivity had significantly decreased 1 day following transient ischemia, and had increased 2 days after ischemia. The first demonstration of the postischemic localizations of PACAP should allow us to gain a more fundamental rationale for developing methods of treating ischemic brain damage with neuroprotective peptides such as PACAP.

Animals↗

PubMed2001

Immunohistochemical study on the distribution of voltage-gated K(+) channels in rat brain following transient focal ischemia.

The present study examined the spatial localizations of voltage-gated K(+) (Kv) channels in the rat brain following transient focal ischemia, using immunohistochemistry. Increased expression of Kv1.2 was obvious in the cerebral cortex, dentate gyrus, amygdala, and hypothalamic areas at 3 days following ischemic insults. There was a significant increase in Kv1.2 immunoreactivity in several cortical regions, including cingulate cortex, infralimbic cortex, dorsal peduncular cortex and piriform cortex. On the contrary, Kv1.2 immunoreactivity had not significantly increased in the hippocampal CA1-3 regions although moderate Kv1.2 immunoreactivity was found in the cell bodies and processes of some neurons. Potentially the first demonstration of spatial changes in Kv1.2 channel expression could provide important molecular basis for altered neuronal excitability after ischemic brain injury.

Amygdala↗

PubMed2001

Requirement of de novo protein synthesis for aminopterin-induced apoptosis in a mouse myeloma cell line.

Cells synthesize nucleotides through de novo and salvage pathways that require the activities of dihydrofolate reductase (DHFR) and hypoxanthine-guanine phosphoribosyltransfease (HGPRT), respectively. Aminopterin, an inhibitor of dihydrofolate reductase, has been demonstrated to allow HGPRT(-) cells to be negatively selected. However, the pathway by which aminopterin leads to cell death remains to be clarified. In this study, we characterized features of cellular responses induced by aminopterin treatment in P3-X63-Ag8.653, a mouse HGPRT(-) myeloma cell line. Upon treatment with aminopterin, the cells readily underwent an apoptotic process, as assessed by DNA fragmentation assay and electron microscopic analysis. Aminopterin-induced apoptosis was drastically reduced by addition of actinomycin D and cycloheximide, indicating that active RNA and protein synthesis is required for the apoptotic effect of aminopterin. Interestingly, the induction of c-myc gene expression preceded the activity of DNA fragmentation in aminopterin-treated cells. Taken together, these results suggest that cells deficient in the salvage pathway of purine biosynthesis are susceptible to aminopterin-induced apoptosis that requires de novo synthesis of proapoptotic factors, including Myc oncoprotein.

Aminopterin↗

PubMed2001

Association between insulin-like growth factor-2 and metastases after transcatheter arterial chemoembolization in patients with hepatocellular carcinoma: a prospective study.

BACKGROUND: Hypoxia up-regulates insulin-like growth factor-2 (IGF-2) and thus stimulates the growth of hepatocellular carcinoma (HCC) cells. In the current study, the authors prospectively evaluated changes in plasma IGF-2 levels in HCC patients after transcatheter arterial chemoembolization (TACE), which usually results in hypoxic insult to liver tissue. The authors also examined the association between changes in plasma IGF-2 levels after TACE and HCC progression, especially in relation to metastasis. METHODS: Plasma IGF-2 levels were measured before and 4 weeks after TACE in 46 patients with HCC. Three months after TACE, the patients were evaluated for the occurrence of metastatic HCC. RESULTS: In 13 of the 46 patients, post-TACE plasma IGF-2 levels decreased by > 20% (Group 1) compared with their basal levels; in 18 patients, the IGF-2 levels changed within 20% (Group 2) and in 15 patients the IGF-2 levels increased by > 20% (Group 3). Plasma IGF-2 levels had a tendency to increase in patients with large-sized tumors, high serum alpha-fetoprotein (AFP) levels, and the heterogeneous uptake of iodized oil. Metastatic foci were found in 9 patients in Group 3 (60%), in contrast to only 3 patients in Group 2 (17%) and in none of the patients in Group 1 (P = 0.001). On multivariate analysis, higher Child-Pugh scores and increased plasma IGF-2 levels (Group 3) were found to be independent risk factors for metastasis. CONCLUSIONS: Increased plasma IGF-2 levels after TACE, which are common in patients with large-sized tumors and high serum AFP levels, appear to be associated with the occurrence of metastatic HCC after TACE.

Carcinoma, Hepatocellular↗

PubMed2001

Differential alterations in the distribution of voltage-gated calcium channels in aged rat cerebellum.

In the present study, we used immunohistochemistry and Western blot analysis to determine region-specific changes in the distribution of voltage-gated calcium channels (VGCCs) in aged rat cerebellum. Age-dependent changes in the staining intensity of the alpha(1C) and alpha(1D) subunits were prominent in the Purkinje cells, whereas there was no change in the expression of the alpha(1A) and alpha(1B) subunits. In the aged rat, in particular, immunoreactivity for the alpha(1C) subunits were increased in the dendrites as well as in the cell bodies of Purkinje cells. On the other hand, decreases in immunoreactivity for alpha(1A) and alpha(1D) subunits were found in the molecular or granular layers. However, only alpha(1D) subunit immunoreactivity was decreased in the aged cerebellum membrane by Western blot analysis that, while not addressing regional specificity, further confirmed an age-related decrease in alpha(1D) subunit. These age-related changes in alpha(1D) subunit expression might reflect a gradual loss of regulation for L-type Ca(2+) channels in the senescent period. The first demonstration of age-related alterations in VGCC expression may provide useful data for future investigations on aging and neurodegenerative diseases.

Aging↗

PubMed2001

Spatial and temporal distribution of N-type Ca(2+) channels in gerbil global cerebral ischemia.

In the present study, we have investigated the spatial and temporal distribution of voltage-gated calcium channels in the gerbil model of global cerebral ischemia using immunohistochemistry. Distinct localizations of P-type (alpha(1A)), N-type (alpha(1B)), and L-type (alpha(1C) and alpha(1D)) Ca(2+) channels were observed in the hippocampus at days 1-5 after ischemic injury. However, increased expression of N-type Ca(2+) channels was detectable in brain regions vulnerable to ischemia only at days 2 and 3 after ischemic injury. The pyramidal cell bodies of CA1-3 areas and the granule cell bodies of the dentate gyrus were intensely stained at days 2 and 3 following ischemic injury. Transient changes in N-type Ca(2+) channel expression were also observed in the affected cerebral cortex and striatum at days 2 and 3 after ischemic injury. Although the present study has not addressed the multiple mechanisms contributing to the intracellular free Ca(2+) concentration ([Ca(2+)](i)) increase in the ischemic brain, the first demonstration of the transient increase in N-type Ca(2+) channels may prove useful for future investigations.

Animals↗