Biomedical subjects

H Han

Publications and source records attributed to H Han.

At least 55 records · Page 3Linked to original sources

PubMed2000

Cloning and characterization of the 5'-flanking region for the mouse phospholipase C-delta1 gene.

To date, little is known about the molecular mechanisms controlling the regulation of phospholipase C-delta1 (PLC-delta1) gene expression. To understand the mechanisms responsible for the regulation of PLC-delta1 gene expression, the 5'-flanking region of the mouse PLC-delta1 gene was isolated from a mouse genomic DNA library. Primer extension analysis revealed that there is a single transcriptional start site located at 127 bases upstream from the translation start codon in the mouse PLC-delta1 gene. DNA sequence analysis showed that the sequence around the transcriptional start site is very GC-rich and has no TATA or CAAT boxes. Transient expression of a luciferase reporter gene under the control of serially deleted 5'-flanking sequences revealed that the 160-base-pair region from -622 to -462 upstream of the transcriptional start site includes a positive cis-acting element(s) for the efficient expression of the PLC-delta1 gene. Gel retardation analysis suggests that multiple transcription factors bind to separate sites on the promoter region. Based on these results, our study suggests that the minimal essential region located at -622 to +70 is fully sufficient to confer high-level transcriptional activity and contains high-affinity binding elements for multiple transcription factors.

Animals↗

PubMed2000

Overexpression of rapsyn modifies the intracellular trafficking of acetylcholine receptors.

Rapsyn is a protein that interacts with the cytoplasmic face of the nicotinic acetylcholine receptors (AChR) to cluster them within postsynaptic membrane of muscle. Here we show that intracellular AChRs are also affected by rapsyn. When rapsyn was co-transfected with AChR into QT-6 fibroblasts, (125)I-alpha-bungarotoxin binding indicated a reduction in the fraction of AChRs expressed on the cell surface, compared to cells expressing AChRs alone. Double fluorescent labeling showed that intracellular AChRs accumulated in patches at the cell periphery, beneath rapsyn-associated cell surface AChR clusters. These patches were observed even when cells were grown in medium containing excess unlabelled alpha-bungarotoxin to mask internalized AChRs, suggesting that they arose from hindered trafficking of newly formed AChRs to the cell surface. Similarly, in the muscle cell line, C2, overexpression of rapsyn resulted in the co-localization of aggregates of intracellular alpha-bungarotoxin binding sites with rapsyn beneath cell surface AChR microaggregates. The results indicate that rapsyn can modify the trafficking of AChRs within the cell and suggest a role in selectively targeting newly synthesized intracellular AChRs to the postsynaptic membrane.

Animals↗

PubMed2000

Human cytomegalovirus gene products US3 and US6 down-regulate trophoblast class I MHC molecules.

The epidemiological correlation between human CMV (HCMV) infection and spontaneous fetal loss has been suggested, but the underlying mechanism is not well understood. Fetal cytotrophoblasts, which are in direct contact with the maternal immune system in the uterus during pregnancy, do not express HLA-A and HLA-B, but express the nonclassical class I HLA-G and HLA-C. It has been shown that both HLA-G and HLA-C are capable of inhibiting NK-mediated cell lysis. In our present study, using human trophoblast cell lines as well as other cell lines stably transfected with the human class I genes, we have demonstrated that HCMV US3 and US6 down-regulate the cell-surface expression of both HLA-G and HLA-C by two different mechanisms. HCMV US3 physically associates with both trophoblast class I MHC species, retaining them in the endoplasmic reticulum. In contrast, HCMV US6 inhibits peptide transport by TAP and thus specifically the intracellular trafficking of class I molecules. Therefore, these findings suggest for the first time a possible molecular mechanism underlying HCMV-related spontaneous pregnancy loss.

3T3 Cells↗

PubMed2000

Association of HLA with Vogt-Koyanagi-Harada syndrome in Koreans.

PURPOSE: To study the distribution of human leukocyte antigen HLA-A/B antigens and HLA-DR/-DQ/-DP alleles and to investigate the immunogenetic background of Korean patients with Vogt-Koyanagi-Harada (VKH) syndrome and clinical course with different types of HLA. METHODS: Human leukocyte antigen typings were performed in 18 Korean patients with VKH syndrome and in 128 healthy control subjects. HLA-A/B loci serologic typing was performed according to the standard microlymphocytotoxicity technique. DNA was extracted through the salting out method, and HLA-DR phenotyping and HLA-DR4, HLA-DQ, and HLA-DP subtyping were performed with the polymerase chain reaction-sequence specific oligonucleotide probe (PCR-SSOP) method. RESULTS: Among HLA-A/B antigens typed by the standard microlymphocytotoxicity method, the frequencies of HLA-A31 (RR = 6.1, P<1x10(-2)) and HLA-B55 (RR = 15.8, P<.05) were significantly increased in the patient group compared with the control group. Among HLA-DR/-DQ/-DP alleles subtyped by DNA methods, the frequencies of HLA-DRB1*04 (RR = 45.1, P<1x10(-7)) and HLA-DRB1*07 (RR = 3.2, P<.05) were significantly increased. However, significant decreases in HLA-DRB1*08 (RR = .1, P<.05), HLA-DRB1*13 (RR = .1, P<.05), and HLA-DRB1*14 (RR = .1, P<.05) frequencies were observed. The result of HLA-DR, HLA-DQ, and HLA-DP subtyping showed the significant increase in DRB1*0405 (RR = 45.1, P<1x10(-7)), DQA1*0302 (RR = 12.0, P<1x10(-4)), DQB1*0303 (RR = 5.0, P<1x10(-2)), DQB1*0401 (RR = 18.9, P<1x 10-6), and DPB1*0501 (RR = 3.8, P<.05). However, significant decreases in DQA1*0101 (RR = .1, P< .05), DQA10102 (RR = .1, P<1x10(-2)), DQA1*0103 (RR = .1, P<.05), DQA1*0501 (RR = .1, P<1x10(-2)), DQB1*0301 (RR = .1, P<.05), DQB1*0601 (RR = .1, P<.05), DPB1*0201 (RR = .3, P<.05), and DPB1*0401 (RR = .1, P<.05) frequencies were also observed. In patients with DRB1*0405 itself or HLA-DRB1*0405-DQA1*0302-DQB1*0401 haplotype, a reduction in visual acuity and ocular complications was common. CONCLUSIONS: These results suggest that HLA-DRB1*0405 itself or HLA-DRB1*0405-DQA1*0302-DQB1*0401 haplotype is greatly increased and may play the most important role in the development and the clinical course of VKH syndrome in Korean patients.

Alleles↗

PubMed2000

G-quadruplexes as targets for drug design.

G-quadruplexes are a family of secondary DNA structures formed in the presence of monovalent cations that consist of four-stranded structures in which Hoogsteen base-pairing stabilizes G-tetrad structures. These structures are proposed to exist in vivo, although direct confirmatory evidence is lacking. Guanine-rich regions of DNA capable of forming G-quadruplex structures are found in a variety of chromosomal regions, including telomeres and promoter regions of DNA. In this review, we describe the design of three separate groups of G-quadruplex-interactive compounds and their interaction with G-quadruplex DNA. Using the first group of compounds (anthraquinones), we describe experiments that provide the proof of concept that a G-quadruplex is required for inhibition of telomerase. Using the second group of compounds (perylenes), we describe the structure of a G-quadruplex-ligand complex and its effect on the dynamics of formation and enzymatic unwinding of the quadruplex. For the third group of compounds (porphyrins), we describe the experiments that relate the biological effects to their interactions with G-quadruplexes.

Base Sequence↗

PubMed2000

G-quadruplex DNA: a potential target for anti-cancer drug design.

In addition to the familiar duplex DNA, certain DNA sequences can fold into secondary structures that are four-stranded; because they are made up of guanine (G) bases, such structures are called G-quadruplexes. Considerable circumstantial evidence suggests that these structures can exist in vivo in specific regions of the genome including the telomeric ends of chromosomes and oncogene regulatory regions. Recent studies have demonstrated that small molecules can facilitate the formation of, and stabilize, G-quadruplexes. The possible role of G-quadruplex-interactive compounds as pharmacologically important molecules is explored in this article.

Animals↗

PubMed2000

Distribution of seven polymorphic markers and haplotypes within the human TNF gene cluster in Koreans.

We examined the distribution of polymorphic elements within the tumor necrosis factor (TNF) gene cluster in 133 normals and in 20 Korean families and compared our data with the results of Caucasians. The genotypes that are shown frequently are TNF a6 (33.8%), TNF b5 (46.6%), TNF c1 (79.3%), TNF d3 (34.6%), TNF e3 (86.5%), TNFB*2 (51.5%), and TNF(-308) A (91.4%). In comparison, TNFa 6 (33.8%), TNFa 13 (4.1%), TNFb 5 (46.6%), TNFd 1 (7.5%), TNFd 3 (34.6%), TNFe 3 (86.5%), TNFe 4 (6.8%), and TNF(-308) A (91.3%) were found more frequently in Koreans than Caucasians (p < 0.01). TNFa 14, TNFa 15, TNFd 8, and TNFe 4 alleles were found only in Korean controls. However, TNFb 6 and TNFb 7 alleles were not found in this study. From the TNF gene of TNFa, TNFb, TNFc, TNFn, TNF(-308), TNFd, and TNFe, 49 different TNF haplotypes were found in 20 Korean families. These data suggest that the TNF microsatellite haplotypes constitute a highly polymorphic system and that will provide useful information on the association between the TNF marker and the immune disease.

Alleles↗

PubMed2000

MICA 5.1 allele is a susceptibility marker for psoriasis in the Korean population.

In order to investigate the possibility that the MICA gene is involved in the pathogenesis of psoriasis, microsatellite polymorphism in the transmembrane region of MICA was studied in 138 Korean patients with psoriasis and compared with 126 healthy controls. The MICA 5.1 microsatellite allele, consisting of 5.1 repetitions of GCT/AGC, showed significantly higher frequencies in all patients and in patients with type I psoriasis than in the controls. HLA-A30-B13-Cw*0602-MICA 5.1 and A1-B37-Cw*0602-MICA 5.1 were found to be an extended haplotype associated with psoriasis. Our results suggest that the MICA 5.1 allele might be a genetic marker related to the early onset of psoriasis and play a secondary role to the HLA-Cw*0602 gene or an unknown causative gene closely linked to HLA-Cw*0602 in the genetic susceptibility to psoriasis.

Alleles↗

PubMed2000

Interleukin-18 and the costimulatory molecule B7-1 have a synergistic anti-tumor effect on murine melanoma; implication of combined immunotherapy for poorly immunogenic malignancy.

Interleukin-18 has been described recently as a cytokine secreted primarily by Kupffer cells. Furthermore, it has been shown that it has significant anti-tumor effects, which are mediated by T cells and natural killer cells, in a manner similar to interleukin-12. Here, we report the evaluation of the effects of the systemic administration of interleukin-18 in combination with B7-1 (CD80) expressed on tumor cells [interleukin-18 + B7-1] on the growth of murine B16 melanoma in vivo. After the subcutaneous inoculation of B16 melanoma, B16 tumors grew progressively in immunocompetent syngeneic C57BL/6 mice. Mice treated with either interleukin-18 or immunized with B7-1-transduced B16 did not demonstrate significant anti-tumor effect. The combination of the two treatments, however, resulted in dramatic suppression of melanoma formation, tumor growth, and a significant improvement in survival. Inhibitory effects of [interleukin-18 + B7-1] on lung metastasis in mice were also detected. Additionally, mice treated with [interleukin-18 + B7-1] showed an increase of natural killer cytotoxicity and interferon-gamma production in vivo. Unlike [interleukin-18 + B7-1], [interleukin-12 + B7-1] did not have a strong anti-tumor effect against B16 melanoma. Histologic characterization after the [interleukin-18 + B7-1] treatment confirmed the infiltration of natural killer cells into the tumor, suggesting that natural killer cells may be involved in the [interleukin-18 + B7-1]-induced anti-tumor effect. This finding was confirmed by showing that depletion of NK1.1+ cells before immunization inhibits the [interleukin-18 + B7-1]-induced anti-tumor effect. Depletion of CD3+ cells in vivo also decreased the anti-tumor effect of [interleukin-18 + B7-1], suggesting the importance of CD3+ T cells. Collectively, combination with interleukin-18 and B7-1 expression has synergistic anti-tumor effects against B16 murine melanoma.

Animals↗

PubMed2000

The association of psoriasis with human leukocyte antigens in Korean population and the influence of age of onset and sex.

To identify HLA markers that may contribute to the genetic susceptibility of Koreans to psoriasis, we studied 84 psoriasis patients, with serologic HLA types of A, B, and genotypes of HLA-Cw, DRB1, DQA1, DQB1, DPB1 alleles. The distribution of HLA markers and the associated haplotypes were analyzed according to age and sex. HLA-Cw*0602 showed the strongest association with psoriasis (relative risk = 36.0, p < 10-8, Pc < 8 x 10-7). The frequencies of A1 (relative risk = 17.0, p < 9 x 10-7, Pc < 7 x 10-5), A30 (relative risk = 5.5, p < 2 x 10-5, Pc < 0.001), B13 (relative risk = 5.6, p < 4 x 10-6, Pc < 3 x 10-4), B37 (relative risk = 30.3, p < 7 x 10-7, Pc < 6 x 10-5), DRB1*07 (relative risk = 5.9, p < 2 x 10-6, Pc < 8 x 10-5), DRB1*10 (relative risk = 26.4, p < 4 x 10-6, Pc < 3 x 10-4), DQA1*02 (relative risk = 6.2, p < 5 x 10-7, Pc < 4 x 10-4), DQB1*02 (relative risk = 2.5, p < 0.005, Pc = ns) and DPB1*1701 (relative risk = 24.6, p < 9 x 10-6, Pc < 7 x 10-4) were also significantly increased in Korean psoriasis patients. Type I and type II psoriasis were subdivided into groups of below and above 30 y of age, because of the significant difference found in HLA-Cw*0602 phenotype frequency between the two groups (83.9% vs. 54.5%, p < 0. 009). In addition to HLA-Cw*0602, the frequencies of B37 and DPB1*1701 were significantly higher in type I as opposed to type II psoriasis. HLA-A30-B13-Cw*0602-DRB1*07-DQA1* 02-DQB1*02 was identified as a high risk haplotype. This was particularly true at an early age in the female. HLA-A33-B44-Cw*1401-DRB1*13-DQA1* 01-DQB1*06-DPB1*0401 was defined as a protective haplotype for psoriasis. The extended haplotype HLA-A1-B37-Cw*0602-DRB1*10-DQA1*01-DQB1*05 was discovered to be a high-risk factor in Koreans. To summarize, this study demonstrates the differential association of HLA according to sex, and identifies a newly found high-risk haplotype and a protective haplotype in Korean psoriasis patients.

Age of Onset↗

PubMed2000

Determinants of plasma total homocysteine levels in Korean chronic renal transplant recipients.

OBJECTIVE: Study the determinants of plasma total homocysteine (tHcy) levels, such as fasting levels of serum creatinine (SCr), albumin, plasma tHcy, folate, B(12), and pyridoxal-5'-phosphate (PLP) in chronic Korean renal transplant recipients (RTR). DESIGN: Cross-sectional study. SETTING: Nephrology & Transplant Service in Catholic University Kangnam St. Mary's Hospital, Seoul, Korea. PARTICIPANTS: Ninety-one chronic Korean RTR with stable renal function who were > or =6 months post-transplant. MEASURES: Used medical record review and anthropometric measurements, and overnight (10 to 14 hours) fasting blood samples were measured for plasma tHcy, PLP, folate, B(12), SCr, and albumin. RESULTS: The prevalence of hyperhomocysteinemia (tHcy > 12 micromol/L) was 56%, and 47% had low plasma folate levels (<3 ng/mL). Linear modeling with analysis of covariance adjusted for age, sex, albumin, SCr, and plasma B-vitamin status revealed that only SCr (standard regression coefficient R = +0.663, P<.001), plasma folate (R = -0.276, P =.001), and B(12) (R = -0.149, marginal, P =.08) were independent determinants of fasting tHcy levels in this patient population. CONCLUSION: Renal function is the major independent determinant of the fasting tHcy levels among chronic, stable Korean RTR, and that B-vitamin status plays a secondary role among such patients.

Adult↗

PubMed2000

Distribution of HLA-A, -B and -DRB1 alleles in patients with sudden sensorineural hearing loss.

This study was performed to investigate the association between human leukocyte antigen (HLA) and susceptibility to sudden sensorineural hearing loss in the Korean population. HLA-A and HLA-B typing using a standard microlymphocytotoxicity technique and HLA-DRB1 genotyping were performed in 35 patients with sudden sensorineural hearing loss and in 206 healthy controls. Prednisone (usual dose 60 mg/day) was administered for 6 days and tapered for an additional 4-6 days. Both initial hearing levels at the onset of deafness and final hearing levels after treatment were examined and evaluated for association with HLA alleles. The frequency of HLA-DRB1*14 was increased in patients with sudden sensorineural hearing loss compared with controls (relative risk [RR] = 2.7, p = 0.016). The frequencies of HLA-A2, -A31, -B52, -B61, -DRB1*04, -DRB1*11 and -DRB1*12 were slightly higher than in the controls, but did not reach statistical significance. When an association between the treatment results and HLA alleles was also evaluated, the frequency of HLA-DRB1*04 was found to be increased in the patients who did not respond to steroid treatment compared with both patients who responded well to steroid (50%, vs 16%, p = 0.034) and controls (RR = 3.0, p = 0.046). These results suggest that there is an association between HLA-DRB1*14 and disease susceptibility and that the presence of HLA-DRB1*04 may be an useful marker for predicting a poor prognosis in Korean patients with sudden sensorineural hearing loss.

Adult↗

PubMed2000

Characterization of a new human B7-related protein: B7RP-1 is the ligand to the co-stimulatory protein ICOS.

Optimal T cell activation requires the interactions of co-stimulatory molecules, such as those in the CD28 and B7 protein families. Recently, we described the co-stimulatory properties of the murine ligand to ICOS, which we designated as B7RP-1. Here, we report the co-stimulation of human T cells through the human B7RP-1 and ICOS interaction. This ligand-receptor pair interacts with a K:(D) approximately 33 nM and an off-rate with a t((1/2)) > 10 min. Interestingly, tumor necrosis factor (TNF)-alpha differentially regulates the expression of human B7RP-1 on B cells, monocytes and dendritic cells (DC). TNF-alpha enhances B7RP-1 expression on B cells and monocytes, while it inhibits it on DC. The human B7RP-1-Fc protein or cells that express membrane-bound B7RP-1 co-stimulate T cell proliferation in vitro. Specific cytokines, such as IFN-gamma and IL-10, are induced by B7RP-1 co-stimulation. Although IL-2 levels are not significantly increased, B7RP-1 co-stimulation is dependent on IL-2. These experiments define the human ortholog to murine B7RP-1 and characterize its interaction with human ICOS.

Amino Acid Sequence↗

PubMed2000

Biphasic response of cardiac NO synthase isoforms to ischemic preconditioning in conscious rabbits.

In conscious rabbits, a sequence of six 4-min coronary occlusion/4-min reperfusion cycles, which elicits late preconditioning (PC), caused rapid activation of calcium-dependent nitric oxide (NO) synthase (NOS) [cNOS; endothelial NOS (eNOS) and/or neuronal NOS (nNOS)], whereas calcium-independent NOS [inducible NOS (iNOS)] activity remained unchanged. The enhanced cNOS activity was associated with increased myocardial levels of NO(2) and/or NO(3) (NO(x)). Twenty-four hours after ischemic PC was induced, the opposite pattern was observed, i.e., there was a pronounced increase in cytosolic iNOS activity but no change in cNOS activity. The initial burst of ischemia-induced cNOS activity was not affected by pretreatment with the antioxidant N-2-mercaptopropionyl glycine (MPG), the protein kinase C (PKC) inhibitor chelerythrine, or the tyrosine kinase inhibitor lavendustin A, indicating that it is independent of the generation of oxidant species and the activation of PKC and tyrosine kinases. In contrast, the delayed upregulation of iNOS 24 h after PC was prevented by pretreatment with N(omega)-nitro-L-arginine, MPG, or chelerythrine before the PC ischemia, indicating that it is triggered by a signaling mechanism that involves the generation of NO, the formation of oxidant species, and the activation of PKC. Taken together, these results demonstrate that, in conscious animals, ischemic PC elicits a biphasic response in cardiac NOS activity, i. e., an immediate activation of cNOS (most likely eNOS) followed 24 h later by a delayed upregulation of iNOS. To our knowledge, this is the first study to directly measure NOS activity after brief myocardial ischemia in vivo. In conjunction with previous functional studies, the data support a distinctive role of NOS isoforms in late PC, with eNOS serving as the trigger on day 1 and iNOS as the mediator on day 2.

Animals↗

PubMed2000

Reduced frequencies of peripheral interferon-gamma-producing CD4+ and CD4- cells during acute Kawasaki disease.

BACKGROUND: This study was performed to analyze the frequencies of peripheral interferon (IFN)-gamma-producing cells at the single-cell level and to determine concentrations of circulating IFN-gamma in the acute and subacute phases of Kawasaki disease (KD). METHODS: Ten patients with KD were studied and seven healthy children were selected as control subjects. Using immunofluorescent detection of intracellular IFN-gamma in CD4-positive and CD4-negative cells, the frequencies of IFN-gamma-producing cells in peripheral blood mononuclear cells were studied. Circulating IFN-gamma levels were measured by enzyme-linked immunosorbent assay. RESULTS: The frequencies of peripheral blood CD4+ and CD4- IFN-gamma-producing cells in acute-phase KD patients were significantly lower than in subacute-phase KD patients and control children (p < 0.05). CD4- cells, thought to be mainly composed of CD8+ cells, appeared to be more responsible for the reduced frequencies of total IFN-gamma-producing cells than CD4+ cells. There were, however, no differences in the frequencies of IFN-gamma-producing cells between KD patients in the subacute phase and control children. In contrast, serum IFN-gamma levels were higher in KD patients in the acute phase than in the subacute phase (p < 0.05). CONCLUSIONS: The above results show increased levels of circulating IFN-gamma and decreased emergence of peripheral IFN-gamma-producing cells in acute KD patients, suggesting transient infiltration of activated IFN-gamma-producing cells into the inflammatory sites during acute KD. These findings also support the hypothesis that IFN-gamma plays an important role in the pathogenesis of KD-related vasculitis.

CD4-Positive T-Lymphocytes↗

PubMed2000

A single amino acid deletion in the carboxy terminal of apolipoprotein A-I impairs lipid binding and cellular interaction.

The carboxy-terminal region of apolipoprotein (apo) A-I has been shown by mutagenesis or synthetic peptides to play an important role in lipid binding. However, the precise functional domain of the C-terminal remains to be defined. In this study, apoA-I Nichinan, a naturally occurring human apoA-I variant with a deletion of glutamic acid 235, was expressed in Escherichia coli to examine the effect of this mutation on the functional domain of apoA-I for lipid binding and related consequences. A dimyristoyl phosphatidylcholine binding study with recombinant (r-) proapoA-I Nichinan showed a significantly slow initial rate of lipid binding. On preincubation with human plasma lipoprotein fractions (d<1.225 g/mL) at 37 degrees C for 1 hour, (125)I-labeled normal r-proapoA-I was chromatographed as a single peak at the high density lipoprotein (HDL) fraction, whereas (125)I-labeled r-proapoA-I Nichinan was chromatographed into the HDL fraction as well as the free r-proapoA-I fraction (23% of radioactivity). Circular dichroism measurements showed that the alpha-helix content of lipid-bound r-proapoA-I Nichinan was reduced, being 62% (versus 73%) of normal r-proapoA-I. Nondenaturing gradient gel electrophoresis of reconstituted HDL particles assembled with r-proapoA-I Nichinan and normal r-proapoA-I showed similar particle size. To study cholesterol efflux, human skin fibroblasts were labeled with [(3)H]cholesterol, followed by incubation with either lipid-free r-proapoA-I or DMPC/r-proapoA-I complex. Fractional cholesterol efflux from [(3)H]cholesterol-labeled fibroblasts to lipid-free r-proapoA-I Nichinan or DMPC/r-proapoA-I Nichinan complexes was significantly reduced relative to that of normal r-proapoA-I or DMPC/r-proapoA-I during the 6-hour incubation. Binding assays of human skin fibroblasts by lipid-free r-proapoA-I showed that r-proapoA-I Nichinan was 32% less bound to fibroblasts than was normal r-proapoA-I. Our data demonstrate that the deletion of glutamic acid 235 at the C-terminus substantially reduces the lipid-binding properties of r-proapoA-I Nichinan, which may cause a reduction in its capacity to interact with plasma membranes as well as to promote cholesterol efflux from cultured fibroblasts.

Apolipoprotein A-I↗

PubMed2000

In vivo assessment of cardiac remodeling after myocardial infarction in rats by cine-magnetic resonance imaging.

The rat infarct model offers important parallels to the process of remodeling after myocardial infarction (MI) in humans. The aim of this study was to test the feasibility of cine fast low-angle shot (FLASH) magnetic resonance imaging (MRI) for assessment of the infarcted and noninfarcted rat heart and to compare the results with established methods. In group A, MRI was done 8-16 weeks after MI on a 7-T scanner using an electrocardiogram-triggered cine-FLASH sequence. We determined left ventricular (LV) volumes and mass, wall thickness, MI size, cardiac output, and ejection fraction. Afterward, MI size was histologically determined. In group B, after MRI eight controls and eight rats 16 weeks after MI underwent conventional hemodynamic measurements for determination of cardiac output, LV volumes, and ejection fraction by electromagnetic flowmeter and pressure-volume curves. LV wet weight was determined. In group A, MRI-acquired MI size (18.5 +/- 2%) was smaller than histology (22.8 +/- 2.5%, p < 0.05) with close correlation (r = 0.97). In group B, agreement in LV mass was found between MRI and wet weight (controls, 537.6 +/- 19.6 vs. 540.3 +/- 18.4 mg; MI, 865.1 +/- 39.2 vs. 865.1 +/- 41.3 mg; for the difference p = ns, r = 0.97, p < 0.05) and in the MRI and flowmeter measurements (cardiac output, controls 73.1 +/- 2.9 vs. 75.2 +/- 2.6 ml/min; MI 82.4 +/- 5.2 vs. 81.9 +/- 3.7 ml/min; for the difference p = ns, r = 0.80, p < 0.05). End-diastolic volume by MRI differed from pressure-volume curves with good correlation (controls, 343.9 +/- 8.4 vs. 262.7 +/- 12.8 microl; MI, 737.0 +/- 70.5 vs. 671.1 +/- 64.1 microl; p < 0.05 each, r = 0.96, p < 0.05). Cine-FLASH-MRI is a valuable diagnostic tool applicable to the rat model of MI. Being noninvasive and exact, it offers new insights in the remodeling process after MI because serial measurements are possible.

Animals↗

PubMed2000

Effect of high or low frequency electroacupuncture on the cellular activity of catecholaminergic neurons in the brain stem.

Although the opioid system plays a pivotal role in the analgesic effect of electroacupuncture (EA), it has been suggested that other peptidergic systems also may be involved in the therapeutic effect of EA. Among several peptides for EA-induced analgesia, catecholamine (CA) is associated with the descending pain inhibitory system. We evaluated whether the different frequencies of EA modified the cellular activity of central CA synthesizing neurons using double labeling immunohistochemistry between Fos-like immunoreactive (FLI) neurons and dopamine-beta-hydroxylase (DBH)/tyrosine hydroxylase (TH)-positive neurons. We observed that different frequencies of EA increased the number of FLI neurons in catecholaminergic neurons, such as the dorsal raphe (DR), hypothalamic arcuate nucleus (Arc), locus coeruleus (LC), A5 noradrenaline cells (A5), and A7 noradrenaline cells (A7). In addition, different frequencies of EA significantly increased the ratio of colocalization between FLI neurons and TH positive neurons in DR, LC and Arc. Only low frequency EA increased the neuronal activity in Arc. The ratio of double labeling between FLI and DBH positive neurons was also elevated at both LC and A5. These data demonstrate that different frequencies of EA increase the cellular activity of central CA synthesizing neurons, suggesting that the CA system plays an important role in EA-induced analgesia.

Animals↗