Search PubMed⌕ Search

Biomedical subjects

H Kim

Publications and source records attributed to H Kim.

At least 307 records · Page 17Linked to original sources
PubMed2000

Pulmonary vascular remodeling distal to pulmonary artery ligation is accompanied by upregulation of endothelin receptors and nitric oxide synthase.

There is increasing evidence that the pathogenesis and progression of many forms of pulmonary vasculopathy are related to abnormalities in endothelial mediators, including endothelin-1 (ET-1) and nitric oxide (NO). Using a rat model of chronic unilateral pulmonary artery ligation, we investigated the role of ET-1 and NO in postobstructive pulmonary vasculopathy (POPV). Eight months after a left thoracotomy with either left main pulmonary artery ligation (ligated group) or no ligation (sham group), rat lungs, including those contralateral to the ligation (hyperperfused group), were fixed and mounted for histologic sectioning. Morphometric measurements were carried out by computer-assisted image analysis and immunohistochemical staining was performed using specific antibodies against ET-1, ETA, and EBB receptors, and endothelial NO synthase (eNOS). Compared to sham lungs, the ligated lungs showed (1) an increase in muscular, adventitial, and intimal thickness of pulmonary artery; (2) increase in external diameter of the bronchial artery (39.8 +/- 2.2 microns vs. 16.8 +/- 0.9 microns in sham group; P < .005) and number of bronchial arteries per bronchiole (3.21 +/- mu 0.26 vs. 1.86 +/- mu 0.21 in sham group; P < .001); and (3) increase in the intensity of eNOS and ETA, B receptor immunoreactivity. No morphometric or immunohistochemical differences were observed between the hyperperfused and sham lungs. These findings suggest that increased synthesis of endothelial NO may serve as a compensatory mediator in ET-1-mediated vascular remodeling.

Animals↗
PubMed2000

Structures of ovine corticotropin-releasing factor and its Ala32 mutant as studied by CD and NMR techniques.

The corticotropin-releasing factor (CRF) is a 41-amino acid peptide-amide hormone, which mediates a general stress-response. It has been reported that the substitution of His-32 in the ovine CRF (oCRF) with Ala brings about a 4.5-fold increase in activity [Kornreich et al. (1992) J. Med. Chem. 35, 1870-76]. Here, we have determined the secondary structure of this Ala-substituted ovine CRF ([Ala32]oCRF) and compare it with that of oCRF using circular dichroism (CD) and NMR techniques in trifluoroethanol (TFE) solution, which is known to stabilize the alpha-helix formation. In contrast to an earlier report, it was observed the alpha-helical structure extends to the C-terminus of oCRF. By analyzing the CalphaH and NH chemical shifts, the properties of local structures of oCRF were elucidated. The oCRF and [Ala32]oCRF have stable alpha-helical structures in the middle region, regardless of pH and temperature, and the alpha-helix initiation regions of these peptides are stabilized as the pH is decreased. However, the [Ala32]oCRF has a more stable alpha-helical structure than oCRF in the vicinity of the substitution region, and it is thought that this is the cause of the increased activity of [Ala32]oCRF.

Alanine↗
PubMed2000

Comparative toxicokinetics of manganese chloride and methylcyclopentadienyl manganese tricarbonyl (MMT) in Sprague-Dawley rats.

The toxicokinetics of manganese (Mn) was investigated in male and female rats either following a single intravenous (iv) or oral dose of MnCl2 (6.0 mg Mn/kg), or following a single oral dose of methylcyclopentadienyl manganese tricarbonyl (MMT) (20 mg MMT/kg or 5.6 mg Mn/kg). The plasma concentrations of manganese were quantified by atomic absorption spectrophotometry (AAS). Upon iv administration of MnCl2, manganese rapidly disappeared from blood with a terminal elimination t1/2 of 1.83 h and CL8 of 0.43 L/h/kg. The plasma concentration-time profiles of manganese could be described by C = 41.9e(-424t) + 2.1e(-0.44t). Following oral administration of MnCl2, manganese rapidly entered the systemic circulation (Tmax = 0.25 h). The absolute oral bioavailability was about 13%. Oral dose of MMT resulted in a delayed Tmax(7.6 h), elevated Cmax (0.93 microg/ml), and prolonged terminal t1/2 (55.1 h). The rats receiving MMT had an apparent clearance (CL/F = 0.09 L/h x kg) about 37-fold less than did those who were dosed with MnCl2. Accordingly, the area under the plasma concentration-time curves (AUC) of manganese in MMT-treated rats was about 37-fold greater than that in MnCl2-treated rats. A gender-dependent difference in toxicokinetic profiles of plasma manganese was also observed. Female rats displayed a greater AUC than that of male rats. Although the apparent volume of distribution of manganese was similar in both sexes, the apparent clearance in males was about twice that observed in females. The results indicated that after oral administration, the MMT-derived manganese displayed higher and more prolonged plasma concentration-time profiles than MnCl2-derived manganese. Thus, MMT-derived manganese appeared likely to accumulate in the body following repeated exposure.

Administration, Oral↗
PubMed2000

Three different turkey luteinizing hormone receptor (tLH-R) isoforms I: characterization of alternatively spliced tLH-R isoforms and their regulated expression in diverse tissues.

Using combinations of reverse transcription-polymerase chain reaction (RT-PCR) and 5'- and 3'-rapid amplification of cDNA ends, three different, alternatively spliced, partial turkey LH receptor (tLH-R) cDNA isoforms were characterized from ovarian mRNA. The first cDNA (tLH-R(intact)) showed 98% and 72-75% similarity with chicken and mammalian LH-R sequences, respectively. The second cloned cDNA isoform (tLH-R(insert)) contained an in-frame TGA stop codon within an 86-base pair insertion that was located in the extracellular domain of the seven-transmembrane region. The tLH-R(insert) isoform could encode a truncated soluble protein isoform that lacked the transmembrane region. The third cDNA isoform truncated the transmembrane region (tLH-R(trunc)) and was derived by the deletion of the last exon by incomplete splicing. Generation of multiple transcripts by alternative splicing was elucidated by partial characterization of tLH-R genomic sequences. The differentially regulated expression of the tLH-R mRNA isoforms in nongonadal tissues and ovarian stromal tissues during various reproductive stages was quantified and analyzed by Northern blot and/or RT-PCR. Alternatively spliced tLH-R isoforms were differentially expressed in a tissue-specific manner in most of the tissues examined. The steady-state levels of tLH-R mRNA isoforms were relatively high in the hypothalamus and optic nerve and relatively low in the cortex, pituitary, and cerebellum when compared to levels in ovarian follicles. In nongonadal reproductive tissues, the steady-state levels of tLH-R mRNA isoforms were relatively high in the uterus and infundibulum and relatively low in the isthmus, oviduct, and magnum. In addition, in the nongonadal peripheral tissues, the steady-state levels of tLH-R isoforms were relatively high in the thyroid gland and relatively low in the spleen, adrenal gland, kidney, skin, bursa, and muscle. The present study suggests that the alternative splicing of LH-R transcripts occurs in a tissue-specific manner and has been evolutionarily conserved (similar results were obtained in chicken and swine). These results raise fundamental questions as to the function of LH-R isoforms in nongonadal tissues.

Alternative Splicing↗
PubMed2000

Three different turkey luteinizing hormone receptor (tLH-R) isoforms II: characterization of differentially regulated tLH-R messenger ribonucleic acid isoforms in the ovary.

We have recently characterized three different, alternatively spliced, partial turkey LH receptor (tLH-R) cDNA isoforms by the combination of reverse transcription-polymerase chain reaction (RT-PCR) and 5'- and 3'-rapid amplification of cDNA ends. The first cDNA (intact form: tLH-R(intact)) showed 98% and 72-75% similarity with chicken and mammalian LH receptor sequences, respectively. The other two cloned cDNA isoforms (insertion and truncated forms: tLH-R(insert) and tLH-R(trunc)) could encode truncated soluble protein isoforms that lack the transmembrane region. Northern blot analysis detected two transcripts of 3.0 kilobases (kb) (tLH-R(intact)) and 1.5 kb (tLH-R(trunc)) in the turkey ovary but could not discriminate a third alternatively spliced transcript (tLH-R(insert)) due to the small 86-base pair difference in the size range of approximately 3.0-kb mRNAs. But with the combination of RNase protection assay, RT-PCR, and Northern blot analysis, three different alternatively spliced tLH-R mRNA isoforms were quantified. Differential expression of the tLH-R mRNA isoforms was demonstrated in ovarian stromal tissue during various reproductive stages and in the theca and granulosa layer through follicular development. To gain a better understanding of the physiological significance of the three different tLH-R isoforms, total RNA from the theca layer through follicular development after prolactin (PRL) treatment was analyzed by RT-PCR. PRL treatment for 8-14 days significantly increased the steady-state levels of total tLH-R mRNAs, including tLH-R(insert) and tLH-R(trunc) mRNAs, compared to those in nontreated controls. In contrast, the steady-state levels of tLH-R(intact) mRNA during the same period was not significantly changed when compared to that in nontreated controls. The present study shows that tLH-R transcripts are alternatively spliced in a tissue-specific manner in the turkey and that the mechanism may, in part, be controlled hormonally.

Alternative Splicing↗
PubMed2000

A role for hepatocyte growth factor during early postimplantation growth of the placental lineage in mice.

Hepatocyte growth factor (HGF) is implicated in placental development; hgfr and hgf null mutant embryos develop placental insufficiency and lethality at 11.5 days (E11.5) after fertilization. The function of HGF in placentation at implantation (E4.5) has not been studied. Using reverse transcription-polymerase chain reaction, we detected HGF receptor (HGFR) mRNA in preimplantation embryos and in cultured blastocyst outgrowths. HGFR protein was detected in trophoblast cells in blastocyst outgrowths. HGF mRNA was not detected at these stages but was detected in the uterus at E5.5. Using in situ hybridization, we detected HGF mRNA in the mesometrial uterus, near the embryo, from E6.5 through E8.5. At E8.5, HGFR mRNA was detected in the chorionic placenta, and HGF mRNA was detected in the allantois. The expression for HGF and HGFR suggested a maternal-to-embryonic communication before the development of the allantois. To test this, blastocyst outgrowths were cultured with HGF. HGF stimulated the outgrowth of trophoblasts in a time-dependent manner and stimulated the expression of proliferating cell nuclear antigen, but it did not scatter trophoblasts. HGF stimulated an increase in the trophoblast cell number, but caused a decrease in the total number of terminally differentiated trophoblasts expressing placental lactogen-1 protein. These data suggest that HGF stimulates the cell division, but not the differentiation, of trophoblast cells during implantation.

3T3 Cells↗
PubMed2000

The relative merits of contemporary measurements and historical calculated fields in the Swedish childhood cancer study.

We present arguments that suggest that historical average calculated fields, which are widely used to estimate biologically relevant exposure to electromagnetic fields, may be less accurate than contemporary spot measurements, which are made at a time following the biologically relevant period of exposure. We use data from the seminal Feychting and Ahlbom study of the health effects of electromagnetic field exposure in a Swedish population to illustrate our argument. We also show how the two types of measurements can produce divergent estimates of risk, and show how in the Feychting and Ahlbom study, the less accurate measurement, the historical average calculated fields, may have resulted in a spurious increase in the estimates of risk. Finally, we consider the implications of our arguments for other studies that rely on wire codes and historical calculations of personal exposure.

Bias↗
PubMed2000

Imaging of malignant lymphomas with F-18 FDG coincidence detection positron emission tomography.

PURPOSE: The authors evaluated the utility of F-18 fluorodeoxyglucose (FDG) coincidence detection (CoDe) positron emission tomography (PET) for staging, post-treatment evaluation, and follow-up assessment of patients with malignant lymphomas. MATERIALS AND METHODS: Fifty-eight patients with histologically proved malignant lymphomas (4 Hodgkin's disease, 54 non-Hodgkin's lymphoma) underwent CoDe PET using F-18 FDG. CoDe PET was performed using a dual-head gamma camera equipped with coincidence detection circuitry. Of the 87 CoDe PET studies, 26 were performed for staging, 38 for post-treatment evaluation, and 23 for follow-up evaluation of recurrence. The entire trunk, from the cervical to the inguinal regions, or selected regions were scanned with the patient in the supine position. No attenuation correction was made and reconstruction was performed using filtered back-projection rather than iterative reconstruction. CoDe PET findings were compared with corresponding results of computed tomographic (CT) and magnetic resonance imaging (MRI), tissue biopsy, or clinical follow-up. RESULTS: For staging, 52 sites were positive on CoDe PET or CT-MRI. CoDe PET detected 49 sites (94%), and CT-MRI showed 47 sites (90%). CoDe PET detected five more lymphomatous lesions and missed three lesions. For post-treatment evaluation, CoDe PET showed a positive predictive value of 100% and a negative predictive value of 83%, but the validated cases numbered only 11. For follow-up for recurrence, CoDe PET had a negative predictive value of 90%, but frequent false-positive findings were noted in the head and neck region as a result of underlying inflammatory changes. CONCLUSIONS: For staging, FDG CoDe PET alone without attenuation correction is not sensitive enough to be used as an independent imaging method, especially for small abdominal lesions. However, it appears to be an accurate method for assessing residual disease and for patient follow-up.

Adolescent↗
PubMed2000

Phylogenetic affiliation of the pseudomonads based on 16S rRNA sequence.

The broad and vague phenotypic definition allowed the genus Pseudomonas to become a dumping ground for incompletely characterized polarly flagellated, gram-negative, rod-shaped, aerobic bacteria, and a large number of species have been accommodated in the genus Pseudomonas. The 16S rRNA sequences of 128 valid and invalid Pseudomonas species, which included almost valid species of the genus Pseudomonas listed in the Approved Lists of Bacterial Names, were obtained: sequences of 59 species were determined and those of 69 species were obtained from the GenBank/EMBL/DDBJ databases. These sequences were compared with the sequences of other species of the Proteobacteria. Fifty-seven valid or invalid species including Pseudomonas aeruginosa (type species of the genus Pseudomonas Migula 1894) belonged to the genus Pseudomonas (sensu stricto). Seven subclusters were formed in the cluster of the genus Pseudomonas (sensu stricto), and the resulting clusters conformed well to the rRNA-DNA hybridization study by Palleroni (1984). The other species did not belong to the genus Pseudomonas (sensu stricto) and were related to other genera, which were placed in four subclasses of the Proteobacteria (alpha, beta, gamma and gamma-beta subclasses). Twenty-six examined species, which were not included in the cluster of the Pseudomonas (sensu stricto) and have not been transferred to other genera as yet, are listed alphabetically: 'Pseudomonas abikonensis', Pseudomonas antimicrobica, Pseudomonas beijerinckii, Pseudomonas beteli, Pseudomonas boreopolis, 'Pseudomonas butanovora', Pseudomonas carboxydohydrogena, Pseudomonas cissicola, Pseudomonas doudoroffii, Pseudomonas echinoides, Pseudomonas elongata, Pseudomonas flectens, Pseudomonas geniculata, Pseudomonas halophila, Pseudomonas hibiscicola, Pseudomonas huttiensis, Pseudomonas iners, Pseudomonas lanceolata, Pseudomonas lemoignei, Pseudomonas mephitica, Pseudomonas pictorum, Pseudomonas saccharophila, Pseudomonas spinosa, Pseudomonas stanier, Pseudomonas syzygii and Pseudomonas woodsii. The phylogenetic affiliations of these 26 pseudomonads species are shown.

Cloning, Molecular↗
PubMed2000

Single species diffusion-influenced reaction A+A-->alphaA: validity of the smoluchowski approach

We investigate the single species diffusion-influenced reaction, A+A-->alphaA with a finite reactivity in all dimensions. The reaction model includes a pure coagulation (alpha=1) or a pure annihilation (alpha=0) model. We apply the hierarchical Smoluchowski approach to study the dimensional aspects of the fluctuation, reactivity, particle size, and alpha(0</=alpha</=1). The theoretical results are compared with those of the Monte Carlo simulations in one, two, and three regular dimensions. The simulation results reveal that the classical Smoluchowski approach is exact in the short time limit in all dimensions and in the long time limit in three dimensions. The hierarchical Smoluchowski approach is found to be numerically exact at all times in two and three dimensions. A numerical method to obtain the exact result of the annihilation for a finite reactivity in one dimension is presented. We also propose a quite accurate analytic solution for an arbitrary alpha for the infinite reactivity in one dimension.

Journal Article↗
PubMed2000

Characterization of soliton damping in the granular chain under gravity

A soliton created in the horizontal granular chain damps due to gravity in the vertical chain. We show that there are two types of propagating modes, quasisolitary and oscillatory, in the vertical chain, depending on the strength of impulse. We find that the type of damping is a power law in depth or time. We also find that the absolute value of the exponent of the power law decreases as the strength of the initial impulse increases in the quasisolitary regime. In the oscillatory regime, however, in which the initial impulse is weak, the power-law exponent is independent of the strength of the initial impulse. We show that the power-law damping is caused by the gravitation which results in the change of the force constant at each contact.

Journal Article↗
PubMed2000

Increased expression of cyclin D1, cyclin E and p21(Cip1) associated with decreased expression of p27(Kip1) in chemically induced rat mammary carcinogenesis.

We induced rat mammary tumors in 7-week-old female Sprague-Dawley rats by intragastric administration of 7,12-dimethylbenz(a)anthracene (DMBA), and analyzed by immunohistochemistry the expression of cyclin D1, cyclin E, p21(Cip1), and p27(Kip1) in carcinomas, atypical tumors, and benign tumors as well as normal mammary glands from the control group. Proliferation status was assessed by immunohistochemistry using bromodeoxyuridine (BrdU). A sequential increase in cyclin D1-, cyclin E-, and p21(Cip1)-positive epithelial cells was observed from normal mammary glands, to atypical tumors, to carcinomas. In contrast, carcinomas showed a significantly lower number of epithelial cells immunoreactive to p27(Kip1) when compared with atypical tumors, benign tumors and normal mammary glands. The immunoreactivities of BrdU, cyclin D1, cyclin E, and p21(Cip1) were positively correlated, whereas that of p27(Kip1) appeared inversely correlated to those of the others. Reverse transcriptase-polymerase chain reaction (RT-PCR) and western blot analysis were also performed to determine the mRNA and protein levels of cyclins and cyclin-dependent kinase inhibitors in tumors and normal mammary glands. The protein levels for cyclin D1, cyclin E and p21(Cip1) in carcinomas and atypical tumors were significantly higher than those in benign tumors, while normal mammary glands showed negligible expression. On RT-PCR, tumors showed higher mRNA levels of cyclin D1 and cyclin E than those of normal mammary glands. Our results suggest that rat mammary carcinogenesis involves increased expression of cyclin D1, cyclin E, and p21(Cip1), associated with decreased expression of p27(Kip1).

9,10-Dimethyl-1,2-benzanthracene↗
PubMed2000

The clinical usefulness of ictal SPECT in temporal lobe epilepsy: the lateralization of seizure focus and correlation with EEG.

PURPOSE: To analyze the relationship between ictal electroencephalography (EEG) and ictal single-photon emission computed tomography (SPECT) and to evaluate the diagnostic usefulness of ictal SPECT as an independent presurgical evaluation technique. METHODS: Sixty-eight patients with temporal lobe epilepsy who underwent temporal lobectomy with good surgical outcome were included in this study. Ictal SPECT was performed during video-EEG monitoring. The ictal EEG was analyzed in 5-second intervals from the initiation of the ictal rhythm. Lateralized EEG dominance was determined by the amplitude, frequency, or regional patterns of ictal rhythm for each 5-second interval. The total ictal EEG was divided into three periods: preinjection (maximum, 30 seconds), the initial part of the postinjection period (30 seconds), and the latter part of the postinjection period (30 to 60 seconds). The results of ictal SPECT were compared with the lateralized EEG dominance of each period and at seizure onset. RESULTS: Fifty-four of 68 ictal EEGs correctly lateralized seizure focus ipsilateral to the side of surgery. Ictal SPECT correctly lateralized the epileptogenic temporal lobe in 61 of 68 patients (mean injection time, 29.8 seconds from onset). Multivariate analysis indicated that only the EEG dominance of the preejection period correlated significantly with the concordant hyperperfusion of ictal SPECT. Correct lateralization of ictal SPECT occurred in 10 of 14 patients with nonlateralized ictal EEG. CONCLUSIONS: Preinjection neuronal activity seems to be important for the accurate interpretation of the hyperperfused patterns of ictal SPECT. Ictal SPECT is an independent and confirmatory presurgical evaluation technique.

Adult↗
PubMed2000

Conformation-dependent antibody response to Pseudomonas aeruginosa outer membrane proteins induced by immunization in humans.

Outer membrane proteins (OMPs) of pathogenic bacteria have been used as protective antigens in developing bacterial vaccines. In the present study, we compared the antibody responses to a Pseudomonas aeruginosa OMP vaccine elicited in humans and rabbits by immunization. Immunization with the vaccine induced high titers of serum IgG antibody both in rabbits and humans but reactivities of the induced antibodies with the OMPs were different. The rabbit immune sera recognized most of the OMPs in the vaccine both in immunoblot and immunoprecipitation analyses. In contrast, a great variation in band pattern and intensity was observed among the human immune sera in immunoblot analysis, but not in immunoprecipitation analysis. Denaturation of the OMPs did not affect the binding activity of the rabbit immune sera as determined by ELISA, but substantially reduced those of the human immune sera and anti-OMP IgG purified from a pooled normal human plasma. These data suggest that antibody response to P. aeruginosa OMPs elicited by immunization in humans is mainly directed against discontinuous or conformation-dependent epitopes, which should be taken into account in developing vaccines, especially for OMP-derived synthetic peptides.

Animals↗
PubMed2000

Characteristics of bursal T lymphocytes induced by infectious bursal disease virus.

Infectious bursal disease virus (IBDV) is an avian lymphotropic virus that causes immunosuppression. When specific-pathogen-free chickens were exposed to a pathogenic strain of IBDV (IM), the virus rapidly destroyed B cells in the bursa of Fabricius. Extensive viral replication was accompanied by an infiltration of T cells in the bursa. We studied the characteristics of intrabursal T lymphocytes in IBDV-infected chickens and examined whether T cells were involved in virus clearance. Flow cytometric analysis of single-cell suspensions of the bursal tissue revealed that T cells were first detectable at 4 days postinoculation (p.i.). At 7 days p.i., 65% of bursal cells were T cells and 7% were B cells. After virus infection, the numbers of bursal T cells expressing activation markers Ia and CD25 were significantly increased (P<0.03). In addition, IBDV-induced bursal T cells produced elevated levels of interleukin-6-like factor and nitric oxide-inducing factor in vitro. Spleen and bursal cells of IBDV-infected chickens had upregulated gamma interferon gene expression in comparison with virus-free chickens. In IBDV-infected chickens, bursal T cells proliferated in vitro upon stimulation with purified IBDV in a dose-dependent manner (P<0.02), whereas virus-specific T-cell expansion was not detected in the spleen. Cyclosporin A treatment, which reduced the number of circulating T cells and compromised T-cell mitogenesis, increased viral burden in the bursae of IBDV-infected chickens. The results suggest that intrabursal T cells and T-cell-mediated responses may be important in viral clearance and promoting recovery from infection.

Animals↗