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Biomedical subjects

S Yamashiro

Publications and source records attributed to S Yamashiro.

At least 109 records · Page 6Linked to original sources
PubMed1994

Alteration of nm23 gene expression during the induced differentiation of human leukemia cell lines.

The nm23-H1 gene is regarded as a human homologue of the mouse nm23 gene, which was expressed in a non-metastatic subline of mouse melanoma K-1735. The expression levels of nm23-H1 mRNA and the levels of protein during induced differentiation of human leukemia cell lines were analysed. mRNA levels of the megakaryoblastic leukemia line MEG-01, which were induced to differentiate into megakaryocyte by TPA, decreased rapidly from 2 days after the start of treatment and became almost undetectable at day 4. Similar down-regulation of nm23-H1 mRNA was also observed in the induced differentiation of the promyelocytic leukemia line HL-60 by TPA, or DMSO into monocyte-macrophage lineage or granulocytes, respectively. The amount of Nm23-H1 protein was analysed by Western immuno-blot analysis using mouse antiserum raised against a recombinant fusion protein with glutathione S-transferase. The amount of Nm23-H1 protein also decreased during the induced differentiation of these leukemia cell lines. On the other hand, in the differentiation of the erythroleukemia line K562 by hemin, levels of both mRNA and protein of Nm23-H1 elevated transiently, then reduced to the original level. When MEG-01 and K562 were stably transfected with nm23-H1 cDNA, MEG-01 transfectants showed reduced sensitivity to the induction of differentiation, whereas K562 transfectants were better induced to synthesize hemoglobin than controls. These findings suggest the possibility that Nm23-H1 protein plays an important role to maintain the proliferation of immature leukemic cells in MEG-01 and HL-60, but it may also play a role in the early stage of K562 differentiation, possibly in the different manner.

Animals↗
PubMed1993

Genetic and enzymatic basis for the differential expression of GM2 and GD2 gangliosides in human cancer cell lines.

Using beta 1,4-N-acetylgalactosaminyltransferase (EC 2.4.1.92) complementary DNA, the correlation of gene expression, enzyme activity, and expression of ganglioside antigens was analyzed in 20 human tumor cell lines. In many lines, GM2 and/or GD2 were the most complex structures examined. Northern blot analysis revealed 5.2- and 3.0-kilobase mRNAs in almost all cell lines expressing GD2 and/or GM2. Some melanoma lines, however, showed no bands although they expressed fairly high levels of GD2. These cell lines expressed very high levels of alpha 2,8-sialyltransferase and the resulting product, GD3. Semiquantitative RT-PCR demonstrated that even cell lines with no bands in Northern blot contained 0.4-2.5% of mRNA level in the highest expressing cell line. These results indicate that GD2 expression on individual cell lines is regulated not only by the expression level of the N-acetylgalactosaminyl transferase but also by the amount of its precursor structure (GD3) and alpha 2,8-sialyltransferase present in the cells. beta 1,4-N-acetylgalactosaminyltransferase activities and mRNA levels generally correlated quite closely. A few lines, however, showed lower enzyme activities than expected from their mRNA levels, indicating the possibility that the enzyme is being regulated by translational or posttranslational modification such as phosphorylation and glycosylation as well as by transcriptional regulation. Depending on their patterns of ganglioside synthesis and expression, the lines examined were classified into 6 groups which were characteristic of different tumor cell types.

Antibodies, Monoclonal↗
PubMed1993

Up-regulation of small GTP-binding proteins smg P21A and ras P21S during TPA-induced differentiation of human leukemia cell lines.

The protein smg p21A/Krev-1/rap 1A was identified as a ras p21-like small G-protein, having the ability to revert v-Ki-ras transformed NIH 3T3 fibroblasts. The expression level of smg p21A and ras p21s during phorbol ester-induced differentiation of HL-60 and MEG-01 cell lines was analyzed by immuno- and Northern blotting. In both cell lines, levels of smg p21 and ras p21s increased quickly in early phase of differentiation along with the appearance of differentiation phenotypes. They increased 3-4 fold on days 1-2, then decreased gradually. The increasing smg 21 mRNA levels also corresponded with that of products. Among ras mRNAs, Ha-ras and N-ras transcripts increased somewhat faster than smg 21. These small G-proteins may play closely related roles in the differentiation of these leukemia cell lines.

Cell Differentiation↗
PubMed1993

MRI study of the inhibitory effect of new spin traps on in vivo CCl4-induced hepatotoxicity in rats.

Acute CCl4 hepatotoxicity is thought to occur as a result of free radicals generated from the metabolism of CCl4 in the liver. With the use of MRI it is possible to detect in vivo a CCl4-induced localized edematous region surrounding the major branch of the hepatic portal vein in the right lobe. Inhibition of the CCl4-induced response has been obtained by pretreatment with the spin trap, PBN, 30 min prior to CCl4 exposure. The inhibitory effect of two new spin traps, M3PO or methyl-DMPO, and PhM2PO or phenyl-DMPO, on in vivo CCl4-induced acute hepatotoxicity was investigated. Both PhM2PO and M3PO were found to inhibit the CCl4-induced response at lower concentrations (0.35 M/kg body weight) than PBN (0.70 M/kg body weight). However, both M3PO and PhM2PO were also found to induce an edematous response at the same concentrations used for the PBN studies (0.70 M/kg body weight). PhM2PO, at a concentration of 0.35 M/kg body weight, was 93% as efficient as PBN, at a concentration of 0.70 M/kg body weight; whereas M3PO, at a concentration of 0.35 M/kg, was 89% as efficient as PBN at 0.70 M/kg body weight. Electron micrographs were obtained from small liver sections taken in proximity to the major branch of the hepatic portal veins of all treatment groups. The electron microscopy investigations support the MRI findings.

Animals↗
PubMed1993

Caldesmon.

Recent research has led to an understanding of the in vitro properties of caldesmon, including the regulation of actomyosin ATPase activity, cross-linking between actin and myosin, enhancement of microfilament stability and stimulation of polymerization of actin. While it remains to be established whether caldesmon functions similarly in vivo, recent studies have suggested that smooth muscle caldesmon regulates the inhibition of vascular smooth muscle tone, and that non-muscle caldesmon plays roles in the regulation of cell motility and cytoskeletal organization in three biological activities: granule movement, hormone secretion and reorganization of microfilaments during mitosis.

Actin Cytoskeleton↗
PubMed1993

Localization of caldesmon and its dephosphorylation during cell division.

Mitosis-specific phosphorylation by cdc2 kinase causes nonmuscle caldesmon to dissociate from microfilaments during prometaphase. (Yamashiro, S., Y. Yamakita, R. Ishikawa, and F. Matsumura. 1990. Nature (Lond.). 344:675-678; Yamashiro, S., Y. Yamakita, H. Hosoya, and F. Matsumura. 1991. Nature (Lond.) 349:169-172). To explore the functions of caldesmon phosphorylation during cytokinesis, we have examined the relationship between the phosphorylation level, actin-binding, and in vivo localization of caldesmon in cultured cells after their release of metaphase arrest. Immunofluorescence studies have revealed that caldesmon is localized diffusely throughout cytoplasm in metaphase. During early stages of cytokinesis, caldesmon is still diffusely present and not concentrated in contractile rings, in contrast to the accumulation of actin in cleavage furrows during cytokinesis. In later stages of cytokinesis, most caldesmon is observed to be yet diffusely localized although some concentration of caldesmon is observed in cortexes as well as in cleavage furrows. When daughter cells begin to spread, caldesmon shows complete colocalization with F-actin-containing structures. These observations are consistent with changes in the levels of microfilament-associated caldesmon during synchronized cell division. Caldesmon is missing from microfilaments in prometaphase cells arrested by nocodazole treatment, as shown previously (Yamashiro, S., Y. Yamakita, R. Iskikawa, and F. Matsumura. 1990. Nature (Lond.). 344:675-678). The level of microfilament-associated caldesmon stays low (12% of that of interphase cells) when some cells start cytokinesis at 40 min after the release of metaphase arrest. When 60% of cells finish cytokinesis at 60 min, the level of microfilament-associated caldesmon is recovered to 50% of that of interphase cells. The level of microfilament-associated caldesmon is then gradually increased to 80% when cells show spreading at 120 min. Dephosphorylation appears to occur during cytokinesis. It starts when cells begin to show cytokinesis at 40 min and completes when most cells finish cytokinesis at 60 min. These results suggest that caldesmon is not associated with microfilaments of cleavage furrows at least in initial stages of cytokinesis and that dephosphorylation of caldesmon appears to couple with its reassociation with microfilaments. Because caldesmon is known to inhibit actomyosin ATPase and/or regulate actin assembly, its continued dissociation from microfilaments may be required for the assembly and/or activation of contractile rings.

Actin Cytoskeleton↗
PubMed1993

[A case of bladder carcinoma representing leukemoid reaction].

A 60-year-old male with locally invasive bladder carcinoma (pT4 pNo Mo) had a remarkable leukocytosis of 64,900/mm3 in the peripheral blood count without any findings of inflammatory disease. The grade 3 transitional cell carcinoma (TCC) measuring 60 by 58 mm involved the prostate, but radiological examinations including abdominal CT scan and isotopic bone scan failed to prove distant metastasis. Serum calcium level was within normal level. Negative bone marrow finding for leukemia strongly suggested a leukemoid reaction by the bladder carcinoma. Preoperative arterial chemoembolization utilizing mitomycin C microcapsules and cisplatin infused into the tumor feeding arteries provided a normalization of leukocyte count (8,200/mm3) in association with a substantial tumor reduction, and was followed by radical cystoprostatectomy. Although the leukocyte count maintained a normal range for 2 months postoperatively, leukocytosis recurred and rapidly progressed to a leukocyte count of 51,300/mm3. CT scan revealed intrapelvic tumor recurrence, and serum analysis for granulocyte colony stimulating factor (G-CSF) demonstrated an elevated value of 130.9 pg/ml (normal, less than 30 pg/ml). The patient is now on systemic chemotherapy. The laboratory data and the response to the treatments would indicate that the leukocytosis in this patient is a leukemoid reaction due to the bladder carcinoma which may release G-CSF. Ten cases of bladder tumor representing leukemoid reaction have been reported in the literature.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1993

Deep breathing test (DBT) in predicting white coat hypertension.

We have evaluated the diagnostic value of deep breathing test (DBT) in detecting the patients with white coat hypertension on the outpatient basis. Thirty patients with untreated mild to moderate hypertension underwent 24-hour ambulatory blood pressure monitoring. Those who had a mean 24-hour blood pressure less than 135/80 mmHg were categorized as having white coat hypertension and the remainder were categorized as sustained hypertension. These two groups were compared with regard to the differences of office blood pressures before and after DBT (i.e., deep breathing 5 times for a minute in sitting position). Although the office systolic pressure significantly fell after DBT in both groups (p < 0.001 vs p < 0.05), there was no significant difference (p = 0.27) between the two groups. On the other hand, the office diastolic blood pressure significantly fell in the white coat hypertensives in contrast with no meaningful fall of it in the sustained hypertensives (p < 0.01 vs p = 0.66). At the cutoff level of -3%, -5% and -10% of the differences in office diastolic blood pressure before and after DBT, the sensitivity for the presence of white coat hypertension were 64.7%, 58.8% and 29.4%, respectively, and the specificity were 61.5%, 84.6% and 100%, respectively. These findings demonstrate that the deep breathing test is useful for identifying white coat hypertension in the outpatient clinic.

Female↗
PubMed1993

[Sinus thrombosis during CDDP and VP-16 (PE) therapy for suprasellar germ-cell tumor: case report].

A case of sinus thrombosis occurring during combination chemotherapy with CDDP and VP-16 (PE) for a suprasellar germ-cell tumor is presented. A 5-year-old girl developed polyuria, polydipsia and headache in April, 1991 and became unconscious on May 10, 1991, when MRI and CT demonstrated a suprasellar tumor and marked hydrocephalus. After a ventriculo-peritoneal shunt operation, radiotherapy and two courses of PE therapy were carried out. During the second course of PE therapy, diabetes insipidus became quite difficult to control and severe hypovolemic hypernatremia developed. While it was being treated, the patient developed a clonic convulsion of her left extremities and visual disturbance. CT scan demonstrated a right parietal hemorrhagic infarction and IV-DSA suggested thrombosis of the superior sagittal sinus. Laboratory data disclosed DIC. The main cause of sinus thrombosis in this patient was considered severe dehydration. It is also possible that cisplatin and steroid played a role. In addition to these, dysfunction of hypothalamus, which is one of the regulatory centers of the plasma concentration of factor VIII, may have contributed to the acceleration of blood coagulation. This case re-emphasized the importance of preventing dehydration and monitoring the blood coagulation fibrinolytic system during PE therapy in patients with a suprasellar germ-cell tumor accompanied with diabetes insipidus.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1993

Effects of Pasteurella haemolytica culture supernate on bovine tracheal smooth muscle.

Pasteurella haemolytica leukotoxin is a ruminant specific leukotoxin that has been implicated in the pathogenesis of shipping fever in cattle. The present study was undertaken to determine the effect of this toxin on bovine airway smooth muscle. In vitro, the addition of culture supernate containing leukotoxin to bovine tracheal smooth muscle resulted in contraction of 55% of the muscle strips tested. Maximum responses were reached rapidly during cumulative additions of this material. In 95% of the muscle strips that responded, maximum responses were obtained after the addition of one or two cumulative doses. Repeated additions of culture supernate resulted in decreased responsiveness. Since responsiveness to other agonists was not affected, these results suggest the development of a condition similar to tachyphylaxis. The contractions were inhibited by antihistamines. Diphenhydramine, at a concentration of 10(-6) M (dose-ratio 7), and mepyramine, at a concentration of 2 x 10(-7) M (dose-ratio 56), blocked the contractions by 84% and 100% respectively. In addition, the contractions were blocked by the muscarinic antagonist atropine, but this inhibition was much weaker (46%) and was present at high concentrations only. Inhibition of the contractions by H1 receptor antagonists suggests that the contractions are mediated via H1 receptors. Since the dose-response relationship is not typical of a drug-receptor interaction, it appears unlikely that the leukotoxin is a direct agonist of H1 receptors. It is proposed that an indirect mechanism of action involving the release of histamine by tissue mast cells is responsible for the leukotoxin-induced contractions.

Animals↗
PubMed1992

Characterization of mitotically phosphorylated caldesmon.

Mitosis-specific phosphorylation by cdc2 kinase causes nonmuscle caldesmon to dissociate from microfilaments (Yamashiro, S., Yamakita, Y., Ishikawa, R., and Matsumura, F. (1990) Nature 344, 675-678; Yamashiro, S., Yamakita, Y., Hosoya, H., and Matsumura, F. (1991) Nature 349, 169-172). To explore the function of mitosis-specific phosphorylation of caldesmon, in vivo- and in vitro-phosphorylated caldesmons have been characterized. We have found that both in vivo and in vitro phosphorylation of caldesmon causes similar changes in the properties, including reduction in actin, calmodulin, and myosin binding of caldesmon, and a decrease in the inhibition of actomyosin ATPase by caldesmon. Rat non-muscle caldesmon is phosphorylated in vitro up to a ratio of 7 mol/mol of protein. Actin-binding constants of both a high affinity (K a = 1.2 x 10(7) M-1) and a low affinity (K a = 1 x 10(6) M-1) site of unphosphorylated caldesmon are reduced to less than 10(5) M-1 with 5 mol of phosphate incorporation per mol of protein. Actin-bound caldesmon can be phosphorylated by cdc2 kinase, which results in the dissociation of caldesmon from F-actin. Caldesmon has a second myosin-binding site in the C terminus, in addition to the N terminus myosin-binding domain previously reported, because the bacterially expressed C terminus of caldesmon shows binding to myosin. Phosphorylation of the C-terminal fragments decreases their myosin-binding affinity as observed with intact caldesmon. These results suggest that caldesmon loses most of its in vitro functions during mitosis as a result of phosphorylation, which may be required for the reorganization of microfilaments during mitosis.

Actins↗
PubMed1992

Expression cloning of beta 1,4 N-acetylgalactosaminyltransferase cDNAs that determine the expression of GM2 and GD2 gangliosides.

GM2 and GD2 gangliosides are sialic acid-containing glycosphingolipids expressed in some normal tissues such as brain and in various tumors such as neuroblastomas, astrocytomas, and malignant melanomas. We used a eukaryotic cell transient expression system to isolate cDNA clones that determine GM2 expression. We developed a new cell line from murine melanoma line B16 by transfecting with the polyoma T antigen gene that was suitable for this purpose. Two cDNA clones, both of which have a continuous open reading frame of 1683 base pairs, were isolated. Although the cloned cDNAs had no primary sequence similarity to reported glycosyltransferases, the deduced amino acid sequence predicted a type II transmembrane protein with an overall structure similar to other glycosyltransferases. The cDNA clones, when stably transfected, determined the expression of GM2 in B16 cells and GM2 and GD2 in the human melanoma line MeWo. Northern blot analysis revealed two transcripts in all cells that expressed either GM2 or GD2 or both. These findings indicate that the cDNAs catalyze the transfer of GalNAc onto GM3 and GD3 by a beta 1,4 linkage, resulting in the synthesis of GM2 and GD2, respectively. Namely they suggest that these cDNAs derive from the UDP-GalNAc: GM3/GD3 beta 1,4 N-acetylgalactosaminyltransferase (EC 2.4.1.92) gene.

Amino Acid Sequence↗
PubMed1992

An ultrastructural study of the Sertoli cell in the water buffalo (Bubalus bubalis).

The ultrastructure of Sertoli cell in the water buffalo (Bubalus bubalis) was observed in a transmission electron microscope. The nucleus had homogeneous nucleoplasm, scarce heterochromatin and multivesicular nuclear body (MNB). The MNB was composed of numerous vesicles and ribosome-like dense structures. The vesicles varied in size and number and contained a sparse and flocculent substance. In the indentation of the nucleus, aggregates of ribosomes were frequently observed. In the apical and middle region of the cell, long mitochondria and microtubules were distributed parallel to the long axis of the cell. Non-laminated smooth ER and some ribosomes were also recognizable throughout this region. In the basal region, widely-distributed laminated smooth ER was characteristic. Microfilament bundles at ectoplasmic specialization were irregularly arranged. Frequently-emerged nodular processes occasionally separated from basal lamina and formed round structures within Sertoli cytoplasm. Although these characteristics of buffalo Sertoli cell were very similar to those of the bovine studied, the aggregate of ribosomes was more developed in the buffalo.

Animals↗
PubMed1991

Mitosis-specific phosphorylation of myosin light chain kinase.

Cell cytosol preparations from mitotic HeLa cells exhibit a kinase activity that phosphorylates myosin light chain kinase (MLCK). This MLCK kinase activity is apparently distinct from the known MLCK kinases, including cAMP-dependent protein kinase, cGMP-dependent protein kinase, Ca(2+)-activated phospholipid-dependent protein kinase, or Ca(2+)-calmodulin-dependent protein kinase II, based on the following criteria. First, the MLCK kinase activity of mitotic cells does not respond to a variety of characteristic activators or inhibitors of these known kinases. Second, one- and two-dimensional peptide maps have revealed that the site of phosphorylation by the MLCK kinase of mitotic cells differs from those by these known kinases. The mitotic MLCK kinase phosphorylates MLCK at a threonine residue at a ratio of up to 1 mol of phosphate/mol of chicken gizzard MLCK. The MLCK kinase is mitosis-specific because mitotic cell extracts show much higher phosphorylation activity than nonmitotic cell extracts.

Animals↗
PubMed1991

Enhancement of carbon tetrachloride-induced liver injury by a single dose of ethanol: proton magnetic resonance imaging (MRI) studies in vivo.

Magnetic resonance imaging (MRI) and localized magnetic resonance spectroscopy (MRS) were used to study the effects of a single dose of ethanol, given 18 h prior to experiments, on CC14-induced acute hepatotoxicity in rats in situ. Localized edema in the centrilobular region of the liver, following exposure to ethanol and CCl4, was detected by 1H-MRI techniques. The edema was characterized by a volume selective spectroscopy (VOSY) method, which measured an increase in water concentration from ethanol and CCl4-treated rat livers, in comparison to control livers. Electron microscopy (EM) of the high intensity regions of the ethanol/CCl4 treated liver sections revealed dramatic subcellular changes such as fragmentation of the granular endoplasmic reticulum (ER), formation of large vacuoles and lipid droplets in the cytoplasmic matrix and extensive swelling of the mitochondria as well as disruption of the cristae. Pretreatment with alpha-phenyl tert-butyl nitrone (PBN), a free radical spin trap, prior to halocarbon exposure, was found to reduce the CC14-mediated high intensity region in the liver images. Electron microscopy of the PBN pretreated CCl4 exposed rat liver sections revealed only minor observable differences in subcellular organization, such as some swelling of the mitochondria, when compared to controls. In addition, these data suggest that ethanol may potentiate CCl4 hepatotoxicity by increased formation of free radical intermediates. Inhibition of the CCl4-induced edematous response in rat liver by PBN demonstrates that free radical intermediates, arising from the metabolism of CCl4, are possibly the causal factor in the initiation of the edema.

Animals↗