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Biomedical subjects

J Kim

Publications and source records attributed to J Kim.

At least 667 records · Page 37Linked to original sources
PubMed1998

Characterization of myogenin expression in myotubes derived from quail myoblasts transformed with a temperature sensitive mutant of Rous sarcoma virus.

During myogenic differentiation of quail myoblasts transformed with a temperature sensitive mutant of Rous sarcoma virus (QM-RSV cells), it was observed that myogenin was continuously expressed in myotubes. In contrast, in myotubes derived from quail primary cells (parent cells of QM-RSV cells), myogenin expression was seen only in the myotubes not having striated structures comprised of myofibrils, but not in myotubes having the structures. The fact that there are not striated structures of myofibrils formed in myotubes derived from QM-RSV cells suggests that these myotubes stop at an immature state prior to the final differentiation. These results also suggest that myogenin is not only required for early steps during differentiation but also maturation steps of myotubes. To clarify the roles of myogenin after myotube formation and maturation, myotubes derived from QM-RSV cells were treated with N,N'-hexamethylene bisacetamide (HMBA) or incubated at 35.5 degrees C, a permissive temperature of RSV for suppression of myogenin expression. On treatment with HMBA, myogenin expression disappeared and myotubes began to incorporate 5-bromo-2'-deoxyuridine (BrdU) into the nuclei, whereas the expression remained in many myotubes on culture at 35.5 degrees C. These results suggest that immature myotubes can return to an up step of differentiation, prior to the commitment step with HMBA treatment, but not with culture at 35.5 degrees C.

Acetamides↗
PubMed1998

Immunohistochemical study of protein kinase C in the testes of cattle and pigs.

We investigated the expression of novel protein kinase C (PKC) delta and theta in the testes of pigs and cattle using Western blot and immunohistochemical analysis. PKC delta and theta are recognized in the testes of pigs and cattle by Western blot analysis. We found in immunohistochemical study that PCK delta was localized in the spermatids of seminiferous tubules, but not in the interstitial cells, while PKC theta was recognized only in the interstitial cells of the testes of in both species. These findings suggest that PKC delta and theta play an important role in the development of spermatozoa and the regulation of androgen in the testicular interstitial cells (probably Leydig cells), respectively.

Animals↗
PubMed1998

Inhibition of calbindin D28K expression by cyclosporin A in rat kidney: the possible pathogenesis of cyclosporin A-induced hypercalciuria.

A recent study by Steiner et al. (Biochem Pharmacol 51: 253-258, 1996) demonstrated a decreased calbindin D28K expression in the kidneys of cyclosporin A (CsA)-treated rats. To evaluate the association of renal calcium handling with calbindin D28K expression in CsA-treated rats, two separate experiments (vehicle [VH] versus CsA groups, 1,25-dihydroxyvitamin D3 [VitD] versus VitD + CsA groups) were done simultaneously. CsA (25 mg/kg per d, subcutaneously) and VitD (0.5 microg/kg per d, subcutaneously) were given for 7 d. The CsA group showed decreased serum calcium, increased urine calcium excretion, and decreased calbindin D28K protein level and immunoreactivity compared with the VH group. The VitD + CsA treatment decreased serum calcium, increased urine calcium excretion, and decreased calbindin D28K protein level and immunoreactivity compared with the VitD alone. CsA treatment did not affect the serum parathyroid hormone and VitD levels. This study demonstrates an association of calbindin D28K expression with the urinary calcium excretion in CsA-treated rats, and suggests that decreased calbindin D28K expression may play a role in renal calcium wasting.

Animals↗
PubMed1998

Tandem zinc-finger gene families in mammals: insights and unanswered questions.

Evidence for the remarkable conservation of mammalian genomes, in both content and organization of resident genes, is rapidly emerging from comparative mapping studies. The frequent occurrence of familial gene clustering, presumably reflecting a history of tandem in situ duplications starting from a single ancestral gene, is also apparent from these analyses. Genes encoding Kruppel-type zinc-finger (ZNF) proteins, including those containing Kruppel-associated box (KRAB) motifs, are particularly prone to such clustered organization. Existing data suggest that genes in KRAB-ZNF gene clusters have diverged in sequence and expression patterns, possibly yielding families of proteins with distinct, yet related, functions. Comparative mapping studies indicate that at least some of the genes within these clusters in mammals were elaborated prior to the divergence of mammalian orders and, subsequently, have been conserved. These data suggest a possible role for these tandem KRAB-ZNF gene families in mammalian evolution.

Amino Acid Sequence↗
PubMed1998

Expression of inducible nitric oxide synthase in the brains of scrapie-infected mice.

The neuronal cell damage caused by inducible nitric oxide synthase (iNOS) in brain has been reported to be associated, at least in part, with many neurodegenerative diseases including Alzheimer's disease. We recently observed vacuolation and astrocytosis in the brains of ME7 scrapie strain-infected C57BL mice. To investigate if these phenomena might have a relationship to iNOS, the level of iNOS expression was measured immunohistochemically and molecular biologically in the brains of scrapie-infected C57BL mice. The number and size of astrocytes were increased and immunoreactivity of glial fibrillary acidic protein (GFAP) was significantly enhanced. iNOS immunoreactivity was observed in the astrocytes of the scrapie-infected group, but not in the control group. iNOS mRNA levels were increased in scrapie-infected mice compared to the levels in non-infected mice of the same age. Our results suggest that iNOS induction in reactive astrocytes is a part of the neurodegenerative mechanisms in scrapie infection.

Animals↗
PubMed1998

Aggregation independent of N-cadherin and neural cell adhesion molecule on quail myoblasts transformed with temperature-sensitive Rous sarcoma virus.

Quail myoblasts transformed with the temperature-sensitive mutant of Rous sarcoma virus (QM-RSV cells) differentiate temperature-sensitively. At 41 degrees C, the cells begin to fuse after about 15-18 h and form multinucleated myotubes, whereas, at 35.5 degrees C, the cells proliferate. Tyrosine-phosphorylation relates to this temperature-sensitive differentiation. In the course of the investigation of QM-RSV cells, when QM-RSV cells were dissociated with EDTA and shaken in DMEM, the aggregation activity was detected. This activity was expressed on the cells cultured at 41 degrees C, but not at 35.5 degrees C. For detailed characterization of the aggregation, cells from which cadherin and/or neural cell adhesion molecule (NCAM) were removed by trypsin treatment were used. It was then observed that temperature-sensitive and calcium-dependent aggregation activity was expressed on the cells treated with trypsin and EDTA (TE-cells), although the TE-cells did not retain either aggregation molecule. The aggregation activity began to be expressed at 2-4 h after temperature shift and increased with the differentiation. The expression of the activity related to the tyrosine-phosphorylation of some protein. The aggregation of TE-cells was completely inhibited by D(+)-mannose, D(+)-glucose, and N-acetyl-D-glucosamine, but D(+)-galactose did not affect the aggregation. Thus, the present results suggest that the aggregation of mannose specific C-type animal lectin recognized on TE-cells relates to the early stage of the differentiation of QM-RSV cells.

Animals↗
PubMed1998

Primary CD56-positive NK/T-cell lymphoma of median nerve: a case report.

Primary extranodal lymphomas of the central nervous system constitute 2% of all malignant lymphomas. The involvement of the peripheral nervous system is very rare. A solitary primary CD56-positive NK/T-cell lymphoma of the median nerve is described in a 70-year-old woman. On physical examination, a rubbery hard mass measuring 2.0 cm in diameter was palpated on the volar aspect of second to third finger of left hand. Excisional biopsy was performed. Under the fascia, a large fusiform tumor of the median nerve encapsulated with the epineurium was noted. Microscopically, the enlarged nerve showed extensive infiltration of atypical lymphoid cells. The lymphoid elements had abundant pale cytoplasm and large vesicular nuclei with peripheral prominent nuclei. The cells strongly expressed T-cell marker (UCHL-1) and natural killer cell marker (CD56). Gene rearrangement study showed rearrangement of T cell receptor (TCR-gamma).

Aged↗
PubMed1998

Time and temperature of stretching as critical control points for Listeria monocytogenes during production of mozzarella cheese.

Different heating times and temperatures commonly used during curd stretching were investigated to determine their effects on the viability of Listeria monocytogenes in mozzarella cheese. Pasteurized whole milk was inoculated with two levels of L. monocytogenes (7 and 3 log CFU/g) and coagulated with citric acid and rennet. The curd was stretched at 55, 66, and 77 degrees C for 1, 3, and 5 min. Results indicated that the majority of L. monocytogenes cells remained in the cheese curds at both inoculum levels. Stretching at 66 degrees C for 3 min reduced the number of L. monocytogenes by 5 log units, whereas stretching at 55 degrees C had a minimal effect. Stretching at 77 degrees C resulted in the complete demise of L. monocytogenes cells (from 7.6 log CFU/g to < 1.0 log CFU/g) in 1 min. If the stretching temperature partially reduced microbial counts, bring (4 degrees C for 12 h) usually had a lethal effect on the remaining microorganisms, but was less effective than the stretching temperature. These results show that stretching curd at 66 degrees C for 5 min or 77 degrees C for 1 min can effectively control L. monocytogenes during the production of mozzarella cheese.

Cheese↗
PubMed1998

Hepatic and intestinal first-pass effects of a new hepatoprotective agent, YH439, in rats.

First-pass effects of YH439 were evaluated after intravenous, intraportal, oral, and intraduodenal administration of the drug, 100 mg/kg body weight, to rats. The first-pass effects of YH439 in the lung and heart seemed to be negligible based on total body clearance values after intravenous and intraportal administration of the drug to rats compared with cardiac output in rats. Approximately 60% of orally and intraduodenally administered YH439 was not absorbed from rat gastrointestinal tract and the F values of YH439 were less than 0.22% after both administration of the drug to rats. Therefore, it could be concluded that approximately 40% of orally and/or intraduodenally administered YH439 could disappeared by hepatic and/or gastrointestinal first-pass effects. The hepatic first-pass effect of YH439 absorbed into the portal vein was approximately 45% (AUC difference between intravenous and intraportal administration) in rats. The AUC0-8hr values of YH439 after oral (18.7 microg min/ml) and intraduodenal (23.4 microg min/ml) administration were significantly smaller than that after intraportal administration (3260 microg min/ml), however, the values were not significantly different between oral and intraduodenal administration, suggesting that the gastric first-pass effect seemed to be negligible and intestinal first-pass effect was considerable in rats. The low F of YH439 in rats could be mainly due to unabsorption (approximately 60%) and hepatic and intestinal first-pass effect (approximately 40%).

Animals↗
PubMed1998

Magnetic field effects on the behavior of radicals in protein and DNA environments.

We have examined the behavior of radical pairs derived by hydrogen abstraction of triplet benzophenone and some of its derivatives from bovine serum albumin, human serum albumin and calf thymus DNA. They have been investigated by means of nanosecond laser flash photolysis techniques. The dynamics of radical pair behavior are shown to be sensitive to external magnetic fields; these effects are interpreted using the established model for the influence of magnetic fields on radical pairs in micellar aggregates, in which intersystem crossing of the radical pair is slowed by the external magnetic field. Our results indicate that proteins and DNA can confine the radicals for a sufficiently long period of time for spin evolution to be affected by external fields. In proteins the radical pair retains its geminate character (i.e. remains confined) for about 0.5-1 microsecond. Interestingly, the magnetic field effects observed in proteins and in DNA seem to occur in distinct timescales; for example, for 2,3,4,5,6-pentafluorobenzophenone bound to DNA, the magnetic field alters the radical reactivity only over times < or = 50 ns, suggesting poor confinement. The timescale for these effects can be increased by promoting Coulombic attraction between DNA and the radical precursor. Electron transfer interactions play a role in the case of DNA.

Animals↗
PubMed1998

Alcohol consumption and sexually transmitted disease risk behavior: partner mix among male Korean university students.

BACKGROUND: This study examined alcohol consumption and sexually transmitted disease risk behavior as related to prostitute visits and sex partner mix among male Korean university students in 1993 to 1994. METHODS: Questionnaires were completed by a representative sample of 1103 university students in Seoul. Lifetime sexually transmitted disease risk behavior was categorized as none, only one, and multiple sexual experiences with prostitutes, whereas risk according to partner mix was classified as no sexual experience with prostitutes, sexual experience with prostitutes only, and with both prostitutes and girlfriends. The proportional odds model was applied to the data. RESULTS: A total of 25.8% of the university students had visited prostitutes--17.6% visited twice or more, and 12.9% had sexual experiences with both prostitutes and girlfriends. Heavier alcohol consumption was significantly related to multiple visits to prostitutes (odds ratio = 1.71) and to sexual experiences with both prostitutes and girlfriends (odds ratio = 2.30). CONCLUSIONS: In this first systematic study of the association between alcohol consumption and sexual experiences among Korean male university students, alcohol use was associated with risky sexual behaviors, and with first and most recent sexual experience with prostitutes, supporting our hypotheses.

Adolescent↗
PubMed1998

Absence of H(+)-ATPase in the intercalated cells of renal tissues in classic distal renal tubular acidosis.

Proton-secretory defect is thought to be a major pathophysiologic mechanism leading to classic distal renal tubular acidosis (dRTA). However, there have been only two case reports demonstrating the absence of proton pump in renal tissues of the patients with Sjögren's syndrome. This study presents two cases of classic dRTA in which the absence of intact H(+)-ATPase was shown in their renal biopsy tissues by immunohistochemistry using a rabbit polyclonal antibody against the 70 kDa catalytic subunit of H(+)-ATPase from bovine brain clathrin-coated vesicles; one of the cases is diagnosed as subclinical Sjögren's syndrome and the other is idiopathic dRTA. A normal human kidney (NC) and the renal biopsy tissues from a patient with chronic tubulointerstitial nephritus whose proton secretory capacity was intact (DC) were compared as controls. The first patient, a 26-year-old woman, presented with quadriparesis. Her serologic tests revealed positive autoantibodies (ANA, SSA; SSB & RF), and a lower lip biopsy confirmed the diagnosis of Sjögren's syndrome. The second patient, a 43-year-old woman, who initially presented with a pathologic fracture of both femoral necks was referred for an evaluation for hypokalemia by the Department of Orthopedic Surgery. Her renal ultrasonography showed medullary calcification, and no autoantibodies were positive. Serum electrolytes and blood gas analyses of the two patients indicated severe hypokalemia and metabolic acidosis, and proton secretory defects were shown by a failure to lower the urine pH during marked acidemia induced by NH4Cl loading and an abnormally low urine-blood pCO2 difference during bicarbonate administration. While stainings with the anti-H(+)-ATPase antibody in NC and DC were strongly positive in intercalated cells in the connecting tubules and collecting ducts, the tissues from both patients with dRTA were devoid of any anti-H(+)-ATPase staining in the intercalated cells. These results support that the pathophysiologic basis of impaired H+ secretion in idiopathic classic dRTA as well as Sjögren's syndrome is the absence of intact H(+)-ATPase pumps in the intercalated cells.

Acidosis, Renal Tubular↗
PubMed1998

Primary pterygium surgery using the inferior conjunctival transposition flap.

The authors investigated a surgical method for primary pterygium without adjunctive therapy and devised a technique called the inferior conjunctival transposition flap. The procedure was performed by making a flap of the inferior conjunctiva after excision of the pterygium, and transpositioning it to make a covering for the bare sclera and donor site and a barrier to pterygium tissue. This method has been used on 54 eyes of 50 patients (mean age 47 years, range 18 to 69 years) with primary pterygium. All of these patients were treated by one surgeon. During a follow-up period of 12 to 26 months (mean 20 months), the pterygium recurred in 3 (5.6%) of the 54 eyes. In all other cases good anatomic and cosmetic results were achieved without any serious complications. The authors concluded that the inferior conjunctival transposition flap is an encouraging technique for the treatment of primary pterygium.

Adolescent↗
PubMed1997

Distinct roles of lymphotoxin alpha and the type I tumor necrosis factor (TNF) receptor in the establishment of follicular dendritic cells from non-bone marrow-derived cells.

In mice deficient in either lymphotoxin alpha (LT-alpha) or type I tumor necrosis factor receptor (TNFR-I), organized clusters of follicular dendritic cells (FDC) and germinal centers (GC) are absent from the spleen. We investigated the role of LT-alpha and TNFR-I in the establishment of spleen FDC and GC structure by using reciprocal bone marrow (BM) transfer. When LT-alpha-deficient mice were reconstituted with wild-type BM, FDC organization and the ability to form GC were restored, indicating that the LT-alpha-expressing cells required to establish organized FDC are derived from BM. The role of LT-alpha in establishing organized FDC structure was further investigated by the transfer of complement receptor 1 and 2 (CR1/2)-deficient BM cells into LT-alpha-deficient mice. Organized FDC were identified with both the FDC-M1 and anti-CR1 monoclonal antibodies in these BM-chimeric mice, indicating that these cells were derived from the LT-alpha-deficient recipient. Thus, expression of LT-alpha in the BM-derived cells, but not in the non-BM-derived cells, is required for the maturation of FDC from non-BM precursor cells. In contrast, when TNFR-I-deficient mice were reconstituted with wild-type BM, they showed no detectable FDC clusters or GC formation. This indicates that TNFR-I expression on non-BM-derived cellular components is necessary for the establishment of these lymphoid structures. TNFR-I-deficient BM was able to restore FDC organization and GC formation in LT-alpha-deficient mice, indicating that formation of these structures does not require TNFR-I expression on BM-derived cells. The data in this study demonstrate that FDC organization and GC formation are controlled by both LT-alpha-expressing BM-derived cells and by TNFR-I-expressing non-BM-derived cells.

Animals↗
PubMed1997

Protein disulfide isomerase as a regulator of chloroplast translational activation.

Light-regulated translation of chloroplast messenger RNAs (mRNAs) requires trans-acting factors that interact with the 5' untranslated region (UTR) of these mRNAs. Chloroplast polyadenylate-binding protein (cPABP) specifically binds to the 5'-UTR of the psbA mRNA and is essential for translation of this mRNA. A protein disulfide isomerase that is localized to the chloroplast and copurifies with cPABP was shown to modulate the binding of cPABP to the 5'-UTR of the psbA mRNA by reversibly changing the redox status of cPABP through redox potential or adenosine 5'-diphosphate-dependent phosphorylation. This mechanism allows for a simple reversible switch regulating gene expression in the chloroplast.

Adenosine Diphosphate↗
PubMed1997

Phenobarbital alters protein binding to the CYP2B1/2 phenobarbital-responsive unit in native chromatin.

Phenobarbital is a classical inducer of the drug metabolizing cytochrome P450 genes, but the molecular mechanism of induction has not been elucidated. Functional analyses have identified a phenobarbital-responsive unit in the rat CYP2B1/2 and mouse Cyp2b10 genes about -2.3 kilobase pairs from the transcriptional start site, but little or no changes in protein binding to this region were observed in vitro. To examine the role of chromatin structure, protein binding to the phenobarbital-responsive unit assessed by in vitro DNase I footprinting was compared with that assessed by DNase I in vivo footprints in native chromatin. A region centered on a putative nuclear factor-1 site was the major protected region in in vitro footprints, and there were no detectable differences in binding between extracts from control and phenobarbital-treated animals. In contrast, phenobarbital treatment dramatically altered the protection pattern in native chromatin. In control samples a core region of about 25 base pairs (bp) centered on the nuclear factor-1 site was protected. However, after phenobarbital treatment, the protection of this core region was increased, and more dramatically the region of protection was extended 20 bp to either side so that a total of about 60 bp were protected. These results provide the first evidence that phenobarbital treatment alters the composition or architecture of proteins binding to the phenobarbital-responsive unit region and indicate that chromatin structure is important in this process. Because proteins are bound to the region in the untreated animal, the mechanism of induction involves the activation of proteins bound to the region and possibly recruitment of additional regulatory proteins rather than conversion of a closed chromatin structure to an open one that can bind regulatory factors.

Animals↗
PubMed1997

Protein-protein interactions among the Aux/IAA proteins.

The plant hormone indoleacetic acid (IAA) transcriptionally activates early genes in plants. The Aux/IAA family of early genes encodes proteins that are short-lived and nuclear-localized. They also contain a putative prokaryotic betaalphaalpha DNA binding motif whose formation requires protein dimerization. Here, we show that the pea PS-IAA4 and Arabidopsis IAA1 and IAA2 proteins perform homo- and heterotypic interactions in yeast using the two-hybrid system. Gel-filtration chromatography and chemical cross-linking experiments demonstrate that the PS-IAA4 and IAA1 proteins interact to form homodimers in vitro. Deletion analysis of PS-IAA4 indicates that the betaalphaalpha containing acidic C terminus of the protein is necessary for homotypic interactions in the yeast two-hybrid system. Screening an Arabidopsis lambda-ACT cDNA library using IAA1 as a bait reveals heterotypic interactions of IAA1 with known and newly discovered members of the Arabidopsis Aux/IAA gene family. The new member IAA24 has similarity to ARF1, a transcription factor that binds to an auxin response element. Combinatorial interactions among the various members of the Aux/IAA gene family may regulate a variety of late genes as well as serve as autoregulators of early auxin-regulated gene expression. These interactions provide a molecular basis for the developmental and tissue-specific manner of auxin action.

Amino Acid Sequence↗