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Biomedical subjects

K Yun

Publications and source records attributed to K Yun.

At least 91 records · Page 5Linked to original sources
PubMed1986

Effects of forskolin on the morphology and function of the rat thyroid cell strain, FRTL-5: comparison with the effects of thyrotrophin.

The effect of diterpene forskolin, a potent stimulator of cyclic AMP (cAMP) in the rat thyroid cell strain FRTL-5, was compared with that of TSH. Forskolin stimulated both the release of cAMP into the culture medium and the accumulation of cAMP in the cytoplasm in a dose-dependent manner, within the range of 0.1-1000 mumol/l. Maximum cAMP concentrations were reached within 15 min of stimulation with forskolin. This is comparable with the effects of TSH. Forskolin also induced morphological changes in cultures of FRTL-5 cells, producing conspicuous cell retraction with arborization and numerous microvilli on the cell surface, specific reorganization of the microfilaments and modulation of the distribution of tubulin and fibronectin. Morphological changes induced by forskolin were always observed 20 to 30 min earlier, and in a higher percentage of cells, than the changes induced by TSH. Cell proliferation, however, was stimulated more effectively by TSH than by forskolin. These observations suggest that TSH might exert its effect on the morphology and growth of FRTL-5 cells, at least in part, through cAMP. The control of morphology and growth might not, however, be regulated solely by the adenylate cyclase and cAMP system.

Animals↗
PubMed1986

Cell differentiation and cell cycle effects on human promyelocytic leukemia cells induced by 12-O-tetradecanoylphorbol-13-acetate.

As has been reported, doses of 12-O-tetradecanoylphorbol-13-acetate (TPA) as small as 1 to 100 ng/ml induced human promyelocytic leukemia HL-60 cells to differentiate terminally into macrophage-like cells rather than toward cells of the granulocytic series. This differentiation was accompanied by the appearance of monocyte/macrophage markers and by the disappearance of myeloid markers from the view point of enzyme cytochemistry. Contrasted to untreated HL-60 cells, TPA-treated cells increased in cell size and showed increased phagocytotic activities against opsonized sheep blood red cells and activated yeast. Nitroblue tetrazolium-positive cells increased rapidly after TPA exposure. The alterations of the cell cycle traverse of HL-60 cells by TPA were analyzed by [3H]thymidine autoradiography, flow microfluorimetry, and mitotic cell counting. TPA sequentially caused (a) inhibition of cells to move from G1 to S near G1/S boundary in G1; (b) temporary inhibition in G2; (c) growth arrest of most cells in G1 within 2 to 3 days after TPA exposure.

Cell Cycle↗
PubMed1986

[A case of extraskeletal osteosarcoma of the retroperitoneum].

A case of extraskeletal osteosarcoma of the retroperitoneum in a 57-year-old woman is reported. A rapidly growing intra-abdominal tumor was noticed eight months before her death. The resected tumor, weighing 1.9 kg, consisted of a large amount of solid mucinous tissue with significant bony materials. Histologically, the tumor showed fibrosarcomatous, chondrosarcomatous and osteosarcomatous growth patterns. A diagnosis of osteosarcoma was made. The CT scan and autopsy findings confirmed that the tumor did not originate from the preexisting bones, but from the retroperitoneum. Differences distinguishing retroperitoneal osteosarcoma from other soft tissue sarcomas were also described from the histological point of view.

Female↗
PubMed1985

Adrenal cortex of Micromys minutus japonicus (Japanese harvest mouse). Its histochemical and fine structural study.

Micromys minutus japonicus (Japanese harvest mouse) is one of the smallest known mammals and is easily maintainable in the laboratory. The adrenal cortex of this animal is described here for the first time. The morphological structure with histochemistry was essentially the same as that of the mouse or the rat. However, the histochemical activity of steroid 3 beta-OH dehydrogenase in the zona glomerulosa was characteristically positive in this animal and electron microscopically Golgi's apparatus and endoplasmic reticulum were prominent in the glomerular cells. The concentration of aldosterone was high in the serum. These findings suggest the hyperfunction of the zona glomerulosa in this animal.

Adrenal Cortex↗
PubMed1985

Cellular structure and function of mouse adrenocortical tumor cells Y-1 in the post-treatment state of low Ca2+.

Under lowered Ca2+ content and in the post-treatment state of low Ca2+, we studied the cellular structure and functioning in mouse adrenocortical tumor cells, Y-1. These cells had been maintained in Ham F12 medium containing 10% fetal calf serum. The Ca2+ present in this complete medium was 0.39 mM. Under a slightly lowered Ca2+ (0.29 mM) produced by EGTA, the cells had many blebs on their surfaces and specific functional activity decreased in steroidogenesis as did ACTH reactivity. In the post-treatment state of a low Ca2+, the cellular surface was covered with many short microvilli and there was greater cellular activity than in the control cells. When the Ca2+ concentration was below 0.17 mM, the cellular structure and functioning were disturbed, and there was no recovery even at the physiological Ca2+ after the removal of EGTA.

Adrenal Cortex Neoplasms↗
PubMed1984

A case report of pancreatic metastasis of an intracranial angioblastic meningioma (hemangiopericytoma) and a review of metastatic tumor to the pancreas.

The authors report a case of solitary metastasis to the pancreas from an intracranial angioblastic meningioma (hemangiopericytoma) and discuss secondary (metastatic) tumors of the pancreas. A 65-year-old man developed a pancreatic tumor 15 years after the craniotomy was performed for a parasagittal meningioma. Histological investigation of the pancreatic tumor excised as a biopsy on exploratory laparotomy revealed a tumor identical to the intracranial meningioma. It was concluded that the intracranial angioblastic meningioma had recurred and metastasized to the pancreas.

Aged↗
PubMed1983

Efficient differentiation of proadipocyte stem cells on nonadherent surfaces: evidence for differentiation without DNA synthesis.

The differentiation of low density BALB/3T3 T proadipocytes that are cultured in standard tissue culture flasks can be induced by heparinized medium containing human plasma. It has been shown that under these conditions, cells first growth-arrest at a distinct state in the G1 phase of the cell cycle, designated GD, and thereafter differentiate within 8 to 12 days. In this paper, we report that the kinetics of proadipocyte differentiation can be significantly accelerated by culture of cells in differentiation-promoting medium on non-adherent surfaces, such as agarose-coated plates or bacteriological Petri dishes. Data also show that in a nonadherent microenvironment extensive differentiation can occur in the absence of DNA synthesis. This was established most convincingly by the demonstration that placement of mitotic cells in heparinized medium containing human plasma and hydroxyurea on agarose-coated Petri dishes induced 70-80% of the cells to GD arrest and differentiate without traversing the S phase of the cell cycle. It is concluded that under appropriate microenvironmental conditions metabolic events that occur solely in the late M or early G1 phase of the cell cycle can mediate the integrated control of proadipocyte proliferation and differentiation.

Adipose Tissue↗
PubMed1983

Gamma delta-mediated deletions of chromosomal segments on F-prime plasmids.

Deleted derivatives of F lac+ proC+ tsx+/- purE+ plasmids ORF203 and F13 were isolated and physically characterized. Among 31 deletions, 24 were adjacent to the gamma delta element on F, four were associated with IS2 or IS3 elements normally present on F, and three displayed additional DNA rearrangements. With the genetic selection employed, the deletion endpoints in the chromosomal segment could fall anywhere within a 210 kb (5 min) region between proC and lac. The distribution of endpoints in this region was not random: the endpoints primarily occurred in an extended region near purE, and a 50 kb segment between tsx and purE was devoid of deletion endpoints. Deletion termini for mutants obtained from F13, which contains an additional 48 kb-segment interposed between gamma delta and the target region on ORF203, displayed a distribution similar to that seen for ORF203. Among simple deletions, there was no marked tendency for the chromosomal deletion endpoints to fall at IS1, IS3, or IS5 elements normally present in this chromosomal region. Point mutations and mutations caused by gamma delta or IS transposition into lac appeared in a small proportion of all plasmids studied.

Chromosome Deletion↗
PubMed1983

Differential mitogenic effects of methyl isobutyl xanthine and a tumor growth factor on G1-arrested 3T3 T proadipocytes at the predifferentiation GD state and the growth-factor deficiency GS state.

Two growth-states exist in the G1 phase of the 3T3 T proadipocyte cell cycle. GD is the arrest state at which proadipocytes must growth-arrest prior to differentiation. GS is the arrest state at which proadipocytes growth-arrest following deprivation of serum or growth factors. In an attempt to further distinguish these arrest states, we have compared the relative ability of a variety of mitogens to induce GD- and GS-arrested cells to initiate DNA synthesis. The data show that GD-arrested cells at both high and low densities can be induced to proliferate by methyl-isobutyl-xanthine (MIX), whereas high and low density GS-arrested cells are not. The data also show that a tumor growth factor can stimulate the proliferation of both high and low density GD- and GS-arrested cells, whereas other agents are poor mitogens for high density GD-arrested cells. We conclude that MIX and a tumor growth factor (TUGF) can serve as probes to study the characteristics of the GD arrest state.

1-Methyl-3-isobutylxanthine↗
PubMed1982

Coupling of growth arrest and differentiation at a distinct state in the G1 phase of the cell cycle: GD.

The differentiation of most mammalian cells is preceded by growth arrest in the G1 phase of the cell cycle, but the characteristics of this state have not been established. We now report that the growth arrest that precedes the differentiation of BALB/c 3T3 T mouse proadipocytes must occur at a distinct state in G1 designated GD. GD-arrested cells are characterized by their ability to differentiate in the absence of DNA synthesis and by their unique sensitivity to the mitogenic effect of isobutylmethylxanthine. Proadipocytes induced to become G1 growth arrested at other states by culture in medium deficient in growth factor or nutrients, by contrast, are unable to differentiate in the absence of DNA synthesis and are not stimulated to proliferate by isobutylmethylxanthine even when they are exposed to differentiation-promoting medium prior to arrest. These data support the conclusion that, prior to the expression of a differentiated phenotype, proadipocytes must arrest their growth at a distinct state in the G1 phase of the cell cycle, GD. These data also provide the basis for the hypothesis that carcinogenesis is associated with defects in the coupling of growth arrest and differentiation at the GD state.

1-Methyl-3-isobutylxanthine↗
PubMed1982

Coupling of proadipocyte growth arrest and differentiation. II. A cell cycle model for the physiological control of cell proliferation.

Experimental evidence is presented that supports a cell cycle model showing that there are five distinct biological processes involved in proadipocyte differentiation. These include: (a) growth arrest at a distinct state in the G1 phase of the cell cycle; (b) nonterminal differentiation; (c) terminal differentiation; (d) loss of the differentiated phenotype; and (e) reinitiation of cell proliferation. Each of these events is shown to be regulated by specific human plasma components or other physiological factors. At two states designated GD and GD', coupling of growth arrest and differentiation is shown to occur. We propose that these mechanisms for the coupling of growth arrest and differentiation are physiologically significant and mimic the regulatory processes that control stem cell proliferation in vivo.

Adipose Tissue↗
PubMed1982

Relationship between colloid droplets of thyroid follicular cells and serum thyroglobulin concentration in neonatal rats after thyrotropin releasing hormone (TRH) injection.

Thyrotropin Releasing Hormone (TRH) shows the obvious and long-durated stimulation to the neonatal thyroid tissue through the pituitary. The sequential changes of serum thyroglobulin (Tg) levels and light and ultrastructural change in the cells of the thyroid gland were studied after TRH injection into neonatal rats. TRH injection induced a rapid increase of the colloid droplets in the thyroid follicular cells followed by a slow increase in serum Tg levels. Ultrastructurally, although marked surface activities consisting of formation of pseudopods and colloid droplets were observed after TRH injection, luminal colloid did not appear to go across the intercellular space between the thyroid follicular cells.

Animals↗
PubMed1982

The effect of alpha-melanocyte-stimulating hormone on the adrenal cortex of the fetal rat.

The effect of alpha-melanocyte-stimulating hormone (alpha-MSH) on the fetal adrenal cortex in rat was studied in vivo and in vitro. In vivo, an injection of alpha-MSH stimulated the adrenal cortex slightly. Treatment of the adrenal cortex with alpha-MSH in organ culture caused hyperfunctional change in the innermost layer of the cortex, the detection of which was done by electron microscope. This treatment caused at the same time an increase in corticosterone in the culture medium. Furthermore, comparison was made between alpha-MSH and ACTH with respect to their effect on the fetal adrenal cortex.

Adrenal Cortex↗
PubMed1980

Early effects of ethylnitrosourea on the LDH isozyme of rat fetal central nervous system.

The sequential changes in isozyme distribution of lactate dehydrogenase and calculated ratios of H- to M-subunit were studied by means of acrylamide gel enzymoelectrophoresis in Wister rat fetal brains from pregnant rats which were administered ethylnitrosourea with a dose of 75 mg/kg on day 14 of gestation, to search for early effects on rat fetal brains of ENU which was transplacental carcinogen and teratogen, from a view point of metabolic aspects. The isozyme patterns were compared to those obtained from normal rat fetal brain. The H/M ratios of ENU-treated group were significantly lower than those of control group. These data suggested that retarded differentiation of rat fetal CNS was induced by administration of ENU as far as LDH was concerned. The present data were discussed in relation to teratogenesis and carcinogenesis.

Animals↗
PubMed1980

LDH isozyme analyses of ethylnitrosourea-induced central nervous system tumors in rats.

To provide the significance of LDH isozymes in rat CNS tumors, the changes in lactic dehydrogenase isozyme and calculated ratios of H- to M- subunit were studied by means of polyacrylamide gel enzymoelectrophoresis in tumor extracts from CNS tumors (7 astrocytomas, 4 oligodendrogliomas, 7 mixed gliomas, 6 anaplastic gliomas, 3 glioependymomas, 1 astroblastoma, 11 neurinomas, 8 anaplastic neurinomas and 1 meningioma in Wistar rats which were induced by ethylnitrosourea). The isozyme patterns were compared to those obtained from normal rat CNS tissues. Among the glioma group, oligodendroglioma showed the highest H/M ratio followed by mixed glioma, glioependymoma, astrocytoma, astroblastoma and anaplastic glioma in order of decreasing of H/M ratios. On the other hand, the H/M ratio of neurinoma was significantly higher than that of anaplastic neurinoma. These observation suggested that determination of LDH isozyme patterns could supplement the histological evaluation of brain tumors.

Animals↗
PubMed1978

Disseminated atypical mycobacteriosis in a child--a case of Mycobacterium sculoflaseum.

A case of disseminated mycobacterial disease caused by mycobacterium sculoflaceum is presented in a three-year-old female. Atypical acid-fast organisms were found in cultures from the tissue of lymph node and bone marrow, gastric juice and feces. Histologically the mesenteric lymph nodes contained numerous large macrophages which had large numbers of acid-fast bacilli. Caseation necrosis was absent. Distinguishing features are the extensive involvement of lymph nodes and bones and the preference for intracellular presence of acid-fast bacilli. Up to the present in Japan there are only 17 reported cases of atypical mycobacteriosis in children.

Child, Preschool↗
PubMed1978

Cystic fibrosis of the pancreas in a human fetus.

Postmortem examination of a 26 week old (postmenstrual) human fetus delivered by Cesarean section revealed meconium ileus and many swollen mucus-secreting cells in the gastro-intestinal mucosa. The pancreas showed extensive fibrosis, acinar destruction and dilatation of ducts containing eosinophilic casts. Mucous glands of the lungs also revealed mucous cells swollen and distended with their secretory products. The patient is believed to have cystic fibrosis of the pancreas, suggesting that the pathologic manifestations of the disease may begin early in fetal life.

Cystic Fibrosis↗