Biomedical subjects

H Maruta

Publications and source records attributed to H Maruta.

At least 55 records · Page 3Linked to original sources

PubMed1995

[Does a tracheal bifurcation shift upward due to increased intraabdominal pressure during laparoscopic surgery?].

To evaluate the influence of increased intraabdominal pressure on a position of tracheal bifurcation, we measured the distance from the tracheal bifurcation to the tip of the endotracheal tube which is fixed on a patient's mouth during a laparoscopic surgery. The distance decreased from 3.5 +/- 1.9 to 3.1 +/- 1.9 cm (P < 0.05) at mean intraabdominal pressure of 8.7 mmHg. This result suggests that the ventilation may become difficult due to the occlusion of the tip of the endotracheal tube by a tracheal bifurcation or due to inadvertent single lung ventilation under inappropriately deep intubation.

Abdomen↗

PubMed1994

The minimal fragments of c-Raf-1 and NF1 that can suppress v-Ha-Ras-induced malignant phenotype.

v-Ha-Ras, an oncogenic Ras mutant, causes malignant transformation of mammalian cells by recruiting c-Raf-1, a cytosolic Ser/Thr kinase, to the plasma membranes/cytoskeleton. The kinase activity of c-Raf-1 resides in the C-terminal half, which activates mitogen-activated protein (MAP) kinase kinase, while it is the N-terminal half of c-Raf-1 (Raf257, residues 1-257) that binds the Ras-GTP complex and can compete Ras GTPase-activating proteins such as NF1 for binding to Ras. However, it still remains to be clarified whether overexpression of Raf257 or its minimal Ras-binding fragment alone is sufficient to suppress Ras-induced malignancy. In this paper we demonstrate for the first time that the 81-amino acid fragment (Raf81, residues 51-131), the minimal Ras-binding fragment of Raf, indeed can suppress v-Ha-Ras-induced malignant phenotype. A further deletion of the first 6 amino acids causes 65% reduction in the Ras binding of Raf81. The resultant 75 amino acid fragment (Raf75, residues 57-131) consists of a single alpha-helix, five anti-paralleled beta-sheets and five loops. We have found that a further deletion of either the first beta-sheet/loop or the last two beta-sheets/loops completely abolishes Ras binding. In addition we have found that the removal of the C-terminal 35 amino acids from a Ras-binding 91-amino acid fragment of NF1 (NF91, residues 1441-1531) does not abolish its ability to suppress the Ras-induced malignancy.

3T3 Cells↗

PubMed1994

An anti-Ras function of neurofibromatosis type 2 gene product (NF2/Merlin).

Previously, we have cloned a candidate for the 595-amino acid neurofibromatosis type 2 tumor suppressor called NF2 or Merlin, with striking sequence similarity in its N-terminal half to an F-actin-binding protein family called TERM, which includes talin, ezrin, radixin, and moesin (Trofatter, J. A., MacCollin, M. M., Rutter, J. L., Murrell, J. R., Duyao, M. P., Parry, D. M., Eldridge, R., Kley, N., Menon, A. G., Pulaski, K., Haase, V. H., Ambrose, C. M., Munro, D., Bove, C., Haines, J. L., Martuza, R. L., MacDonald, M. E., Seizinger, B. R., Short, M. P., Buckler, A. J., and Gusella, J. F. (1993) Cell 72, 791-800). In an attempt to determine whether NF2 serves as a tumor suppressor and if so whether its N-terminal half is involved in its anti-oncogenicity, both full-length NF2 and its N-terminal half (NF2-N, residues 9-359) have been expressed in v-Ha-Ras-transformed NIH/3T3 cells. Like neurofibromatosis type 1 (NF1) fragments (Nur-E-Kamal, M. S. A., Varga, M., and Maruta, H. (1993) J. Biol. Chem. 268, 22331-22337), full-length NF2 can reverse the Ras-induced malignant phenotype, i.e. anchorage-independent growth in a soft agar, and restore contact inhibition of cell growth, indicating that NF2 is indeed a tumor suppressor. Furthermore, NF2-N also suppresses the Ras-induced malignant phenotype, although it appears to be less effective than the full-length NF2. These observations indicate that the anti-Ras function of NF2 resides in part in its N-terminal half. Thus, NF2 appears to be a new member of the tumor suppressor family of actin-cytoskeleton-associated proteins, which includes vinculin, alpha-actinin, tropomyosin-1, gelsolin, and tensin.

3T3 Cells↗

PubMed1994

Localization of heparin-binding, neurite outgrowth and antigenic regions in midkine molecule.

Midkine is a 13kDa heparin-binding polypeptide rich in basic amino acids and cysteine and has neurite outgrowth, neuronal cell survival and other activities. We used chemically synthesized MK half molecules as well as recombinant MK deficient in N-terminal and C-terminal sequences to localize its active regions. The principal and conformation-dependent heparin-binding site was found in the C-terminal half. On the other hand, 13 amino acid residues in the C-terminal end were responsible for the MK antigenicity. The C-terminal half, but not the N-terminal half, had potent neurite outgrowth activity. However, in contrast to the whole molecule, the C-terminal half could not support the survival of embryonic brain neurons.

Amino Acid Sequence↗

PubMed1994

Sodium benzylideneascorbate induces apoptosis in HIV-replicating U1 cells.

U1 cells, a subclone of U937 cells chronically infected with human immunodeficiency virus type 1 (HIV-1), produced HIV-1 only in the presence of inducers such as 12-O-tetradecanoxylphorbol 13-acetate (TPA) or tumor necrosis factor (TNF)-alpha. The expression of HIV-antigen on U1 cells induced by TPA or TNF-alpha was found to be prevented by sodium 5,6-benzylidene-L-ascorbate (SBA) in a concentration-dependent manner. Treatment of U1 cells with SBA in the presence of inducers resulted in cell death with cell shrinkage, chromatin condensation and DNA fragmentation into nucleosomal oligomers, characteristics of apoptosis. In contrast, SBA had scarcely any apoptotic effect on U1 cells in the absence of inducers. SBA did not also induce apoptosis in parental U937 cells in the presence or absence of inducers. These results suggest that HIV-replicating U1 cells selectively undergo apoptosis on treatment with SBA.

Antiviral Agents↗

PubMed1994

Regulation of the Ras signalling network.

The mitogenic action of cytokines such as epidermal growth factor (EGF) or platelet derived growth factor (PDGF) involves the stimulation of a signal cascade controlled by a small G protein called Ras. Mutations of Ras can cause its constitutive activation and, as a consequence, bypass the regulation of cell growth by cytokines. Both growth factor-induced and oncogenic activation of Ras involve the conversion of Ras from the GDP-bound (D-Ras) to the GTP-bound (T-Ras) forms. T-Ras activates a network of protein kinases including c-Mos, c-Raf-1 and MAP kinase. Eventually the activation of MAP kinase leads to the activation of the elongation factor 4E and several transcription factors such as c-Jun, c-Myc and c-Fos. There are several modulators of Ras activity, such as the GTPase activating proteins (GAP1 and NF1), which stimulate the conversion of T-Ras to D-Ras. A series of small NF1 fragments, which bind T-Ras, as well as truncated forms of derivatives of c-Raf-1, c-Jun and c-Myc, are capable of blocking the T-Ras-activated mitogenesis in a competitive manner. These agents offer a unique opportunity to control the proliferation of T-Ras-associated tumors, which represent more than 30% of total human carcinomas.

Animals↗

PubMed1993

rho GAP of 28 kDa (GAP2), but not of 190 kDa (p190), requires Asp65 and Asp67 of rho GTPase for its activation.

Two distinct GTPase-activating proteins (GAPs), i.e. rho GAPs of 28 kDa (GAP2) and of 190 kDa (p190), stimulate the intrinsic GTPase activity of the rho protein. The rho GAP activity of p190 resides in its C-terminal domain (p190C). Neither GAP2 nor p190C activates the ras GTPase. We replaced Asp65 and Asp67 residues of rho GTPase with the corresponding ras residues and examined whether the domain containing them is involved in its activation by rho GAPs. Mutation of either Asp65 to Glu or Asp67 to Ser did not change the Kd value for GTP gamma S of the rho protein. The Ser67 mutation reduced the intrinsic GTPase activity of the rho protein, while no change was observed with the Glu65 mutation. Both mutations abolished activation of rho GTPase by GAP2. The GAP2-dependent activation of rho GTPase was inhibited by the addition of GTP gamma S-bound wild type rho but not by either GTP gamma S-bound Glu65- or Ser67-rho, indicating that both Asp65 and Asp67 are essential for interaction of rho protein with GAP2. On the contrary, p190C activated both Glu65- and Ser67-rho GTPases to the extent and in a dose dependence to those seen in the wild GTPase. These results suggest that GAP2 and p190 interact with different residues or domains of the rho GTPase for their activation.

Amino Acid Sequence↗

PubMed1993

Novel inhibitors of poly(ADP-ribose) glycohydrolase.

The inhibitory effects on poly(ADP-ribose) glycohydrolase purified from human placenta of three classes of chemically defined tannins; gallotannins, ellagitannins and condensed tannins, were examined in vitro. Oligomeric ellagitannins were found to be most potent inhibitors of poly(ADP-ribose) glycohydrolase, their potencies increasing with increasing number of monomeric residues (dimer < trimer < tetramer). Monomeric ellagitannins and gallotannins were less inhibitory. Condensed tannins, which consist of an epicatechin gallate oligomer without a glucose core, were not appreciably inhibitory. A structure-activity study showed that higher-order conformations of the conjugates with glucose of hexahydroxydiphenoyl and valoneoyl groups, which are unique components of ellagitannins, cooperatively potentiated the inhibitory activity.

Enzyme Inhibitors↗

PubMed1993

The GTPase-activating NF1 fragment of 91 amino acids reverses v-Ha-Ras-induced malignant phenotype.

The human neurofibromatosis type 1 gene encodes a Ras GAP (GTPase-activating protein) of 2818 amino acids called NF1. This GAP contains a domain of 338 amino acids (residues 1194-1531) called NF1-GRD, which shares 26% sequence identity with the C-terminal domain (GAP1C, residues 709-1044) of another Ras GAP called GAP1. Both NF1-GRD and GAP1C activate normal Ras GTPases but not oncogenic mutants such as v-Ha-Ras. Any attempt to reverse the v-Ha-Ras-induced malignant transformation by the GAP1C has, so far, been unsuccessful. However, we have found that when the NF1-GRD is overexpressed in v-Ha-Ras-transformed NIH/3T3 cells, it greatly reduces their ability to form colonies in a soft agar, the property tightly associated with their malignancy. This is, so far, the first demonstration that a Ras-binding protein can act as a potent antagonist of the oncogenic Ras mutants in mammalian cells. In an attempt to further screen the smallest anti-oncogenic fragment derived from the NF1-GRD, we have prepared a series of its deletion mutants and examined their interaction with Ras first by monitoring their GAP activity (ability to activate the normal Ras GTPase). The deletion analysis has revealed that the N-terminal 247 amino acids (residues 1194-1440) of NF1-GRD are not required for its GAP activity, suggesting that its remaining domain of 91 amino acids (NF91, residues 1441-1531) is sufficient to bind the v-Ha-Ras, although its GAP activity is 20 times lower than the NF1-GRD. The NF91 is indeed able to reverse the v-Ha-Ras-induced malignant transformation as the NF1-GRD. The NF91 is, so far, the smallest among the tumor suppressor proteins that show the anti-v-Ha-Ras action in vivo. Thus, the NF91 appears to be a good starting material from which a smaller and more potent v-Ha-Ras antagonist could be devised to be used as a potential cure for the human cancers caused by the Ras mutants.

3T3 Cells↗

PubMed1993

Structural characterisation of native and recombinant forms of the neurotrophic cytokine MK.

The retinoic acid (RA)-inducible midkine (MK) gene encodes a heparin-binding protein which can induce neurite outgrowth in cultured mammalian embryonic brain cells. This cytokine shares 65% amino acid sequence identity with another RA-inducible cytokine, pleiotropin (PTN). Both proteins contain 10 conserved cysteine residues, all of which appear to be disulphide linked. MK and PTN are also rich in lysine and arginine residues rendering them susceptible to proteolysis during purification, and making large-scale preparation of these molecules inherently difficult. Recombinant MK has been expressed as a fusion protein using a pGEX vector transfected into E. coli. To enable refolding of MK, the fusion protein was stored in solution at 4 degrees C for 14 days in the presence of dithiothreitol (DTT). Thrombin cleavage of the fusion protein, post storage, typically generated 5 mg of MK per litre of bacterial pellet. To establish the structural integrity of the recombinant product, we have analysed the refolding kinetics and compared the disulphide bond assignment of recombinant MK with that of native MK and native PTN. The synergistic use of micropreparative HPLC, to separate and recover in small eluant volumes enzymatically derived peptide fragments, with matrix assisted laser desorption mass spectrometry (MALD-MS) and N-terminal sequence analysis has allowed the unambiguous identification of the disulphide bonded fragments of native and recombinant MK. The disulphide bond assignment of MK is C12-C36, C20-C45, C27-C49, C59-C91 and C69-C101, and is equivalent to that of PTN.

Amino Acid Sequence↗

PubMed1993

Midkine, a novel neurotrophic factor, is present in senile plaques of Alzheimer disease.

An affinity purified antibody specific for midkine (MK) stained senile plaques in the brain of Alzheimer disease (AD) patients. After formic acid treatment, plaque staining was dramatically enhanced, and almost all beta-amyloid protein (BAP) deposits were also immunoreactive for MK. MK-immunoreactivity was not observed in normal cellular components nor in other pathological lesions including tangles in AD brain. Control brain sections were not immunoreactive for MK. The presence of MK in AD brain but not in control brain was confirmed by Western blotting. MK appears to be involved in the pathological process leading to senile plaque formation.

Aged↗

PubMed1993

Preferential degradation of protein-bound (ADP-ribose)n by nuclear poly(ADP-ribose) glycohydrolase from human placenta.

Poly(ADP-ribose) glycohydrolase, extensively purified to homogeneity from nuclei of human placenta, is composed of a single polypeptide with a molecular mass of 71,000 daltons on sodium dodecyl sulfate-polyacrylamide gel. Judging from its physico-chemical and catalytic properties, the enzyme is similar to the nuclear glycohydrolase (glycohydrolase I), but not to the cytoplasmic glycohydrolase (glycohydrolase II) that has been purified from guinea pig liver (Tanuma, S., Kawashima, K., and Endo, H. (1986) J. Biol. Chem. 261, 965-969; Maruta, H., Inageda, K., Aoki, T., Nishina, H., and Tanuma, S. (1991) Biochemistry 30, 5907-5912). The rates of hydrolysis of (ADP-ribose)n bound to various proteins by the purified nuclear glycohydrolase were higher than those of the corresponding free polymers. Kinetic analyses revealed that the enzyme had more activity toward poly(ADP-ribose) bound to histone H1 or to poly(ADP-ribose) polymerase than toward oligo(ADP-ribose) bound to cytoplasmic proteins from mitochondria or mRNA ribonucleoprotein although the Km and Vmax values were dependent on the chain length (n). In contrast, cytoplasmic glycohydrolase purified from human erythrocytes was more active toward oligo(ADP-ribose) (n = 2.6 or 4.2) bound to the cytoplasmic proteins than to poly(ADP-ribose) (n = 14.6) bound to histone H1, and their kinetic parameters of glycohydrolase II were rather dependent on the acceptor molecules for (ADP-ribose)n. These results suggest that poly(ADP-ribose) glycohydrolase I may play an important role in regulation of poly(ADP-ribosyl)ation levels on chromosomal proteins in nuclei.

Amino Acids↗

PubMed1993

Midkine, a retinoic acid-inducible growth/differentiation factor: immunochemical evidence for the function and distribution.

Midkine (MK) is a heparin-binding growth factor specified by a retinoic acid responsive gene. A rabbit was immunized against recombinant MK produced in L cells, and the resulting antibody was affinity purified using MK-glutathione S-transferase fusion protein as a ligand. The MK-specific antibody was used to investigate the function and distribution of MK. MK of the same size as the recombinant MK produced in L cells (13 kDa) was strongly detected in a 13-day rat embryo. Weak expression was observed in the brains of a 19-day embryo, neonates, and adults. In the 13-day mouse embryos, high levels of MK were detected on the surfaces of brain cells, as well as in basement membranes and in the epithelial cells of the intestine, the jaw, and the rib. Nerve cells from the brains of 13-day or 19-day rat embryos extended neurites about twofold more efficiently on MK-coated dishes than on poly-L-lysine-coated dishes. Furthermore, anti-MK antibody inhibited neurite extension not only on MK-coated dishes, but also on poly-L-lysine-coated dishes. These results suggest that MK is an endogenous neurite outgrowth factor involved in the development of the central nervous system. Anti-MK antibody was also found to inhibit growth of Wilms' tumor cells, which secreted MK into culture medium. Thus, overproduction of MK is involved in enhanced growth of Wilms' tumor cells.

Amino Acid Sequence↗

PubMed1993

Midkine (MK), a retinoic acid (RA)-inducible gene product, produced in E. coli acts on neuronal and HL60 leukemia cells.

We have shown previously that (i) retinoic acid (RA), an anti-neoplastic agent, activates the midkine (MK) gene in mammalian embryonic carcinoma cells, and that (ii) the MK of 118 amino acids, purified from L cells, induces neurite outgrowth of mammalian embryonic brain cells. In this paper, we describe an unconventional strategy for the purification of a fully active MK from E. coli with a high yield. The MK was overproduced in E. coli as a glutathione S-transferase (GST) fusion protein. The MK fusion protein extracted from the bacterial inclusion bodies with guanidine-HCl was renatured, refolded slowly and cleaved by thrombin at the site where the GST links to the MK. The purified free MK, like RA, induced neurite outgrowth from central neurons of the mouse spinal cord, and suppressed the growth of human HL60 leukemia cells in vitro. Unlike RA, however, the MK did not induce granulocytic differentiation of HL60 cells. Furthermore, the MK supported the survival of an NGF-insensitive sensory neuron subpopulation(s) from chicken embryo dorsal root ganglion. Thus, the actions of the MK and leukemia inhibitory factor (LIF) are surprisingly similar. There is no sequence similarity between MK and LIF, however, and unlike MK, LIF production does not appear to be RA-inducible.

Amino Acid Sequence↗

PubMed1993

[A case report of pseudolymphoma of the kidney and orbit].

Pseudolymphoma is reactive extranodal lymphocytosis, and it's lymphocytes are so minimally atypical that it is basically benign. The patient was a 68-year-old female with pain in the left back and lower abdomen. Plain CT (computerized tomogram) of the kidney revealed a mass in the left kidney. It had a smooth surface and higher density than parenchyma. Similarly a left orbital mass was revealed by CT. We could not deny the mass to be a malignant tumor, so we took specimens from these lesions by an open biopsy. Histological examination of these specimens showed pseudolymphoma. Pseudolymphoma of the left kidney was reduced in its size by treatment with prednisolone. The patient is continuously followed up to date.

Aged↗

PubMed1992

[Studies on the production rate of estradiol in the testis in male infertility--studies of the predictive values on therapeutic efficacy in patients with oligozoospermia].

It is surmised that studies on the relationship between the endocrinological milieu and therapeutic efficacy in male infertile patients are essential in elucidating the etiology of this disease and devising effective therapeutic methods. The relation between serum gonadotropin level and therapeutic efficacy has already been reported. In the present study, we investigated the basal levels of two sex steroids, i.e., testosterone and estradiol, and the estradiol:testosterone (E2/T) ratio, and also the increases in these parameters after the administration of hCG to human subjects presenting various degrees of testicular dysfunction, e.g., male infertile patients, aged males, Klinefelter's syndrome and hypogonadotropic hypogonadism. Special attention was given to the characteristics of the reserve capacity for secretion of estradiol in male infertile patients. The hCG test was performed on a total 527 subjects, including 65 normal adult males. The reserve capacity for the secretion of estradiol was investigated on the basis of the increasing rate in the serum E2/T ratio. The increasing rate in the serum E2/T ratio was statistically larger in subfertile males, oligozoospermia and azoospermia in comparison with the normal adult males. On the other hand, the aged males did not show any difference from the normal adult males, whereas the results were significantly lower in the male subjects with Klinefelter's syndrome and hypogonadotropic hypogonadism. It was considered that the increase in the serum E2/T ratio is one characteristic of the gonads of male infertile patients. The results of multiple regression analysis showed that the LH level, the pretreatment sperm concentration and the increasing rate in the serum E2/T ratio were important factors determining the increase in the sperm concentration after treatment. Accordingly, for cases of oligozoospermia characterized by an LH level of 13.7mIU/ml or less and a sperm concentration of 5 x 10(6)/ml or more, the relationship between the increasing rate in the serum E2/T ratio and therapeutic efficacy was investigated. It was found that the increasing rate in the serum E2/T ratio was significantly greater in the therapeutically ineffective cases compared with the therapeutically effective cases. On the basis of this finding, it was surmised that the percentage increase in the serum E2/T ratio is one index reflecting testicular function. In addition, for cases of oligozoospermia characterized by an LH level of 13.7mIU/ml or less, a sperm concentration of 5 x 10(6)/ml or more and the increasing rate in the serum E2/T ratio of 4.01 or less, the relationship between the degree of spermatogenesis and therapeutic efficacy was investigated.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

PubMed1992

Mouse mammary tumor virus gene expression is suppressed by oligomeric ellagitannins, novel inhibitors of poly(ADP-ribose) glycohydrolase.

Oligomeric ellagitannins (nobotanins B, E, and K) were found to be potent inhibitors of poly(ADP-ribose) glycohydrolase purified from mouse mammary tumor 34I cells. Kinetic analysis revealed that the inhibition of nobotanin B (dimer) was competitive with respect to the substrate poly(ADP-ribose), whereas nobotanin E (trimer) and nobotanin K (tetramer) exhibited mixed-type inhibition. These results suggest that the dimeric structure of ellagitannin may have a functional domain that competes with poly(ADP-ribose) on the poly(ADP-ribose) glycohydrolase molecule. To determine the inhibitory effects of oligomeric ellagitannins on poly(ADP-ribose) glycohydrolase in vivo, we examined their effects on de-poly(ADP-ribosyl)ation of some chromosomal proteins in intact 34I cells that was induced by glucocorticoid treatment. Nobotanin B caused concentration-dependent inhibition of glucocorticoid-induced de-poly(ADP-ribosyl)ation of HMG 14 and 17 and histone H1 in intact 34I cells. Interestingly, this inhibition was associated with suppression of the glucocorticoid-sensitive mouse mammary tumor virus (MMTV) mRNA synthesis. In contrast, nobotanin E and K had little inhibitory effect on either de-poly(ADP-ribosyl)ation of these proteins or induction of MMTV transcription after glucocorticoid treatment. Nobotanin B but not E and K was taken into 34I cells. These results may suggest that the suppression of glucocorticoid-sensitive MMTV transcription results from in vivo inhibition of poly(ADP-ribose) glycohydrolase by nobotanin B. These results also indicate the importance of de-poly(ADP-ribosyl)ation of HMG 14 and 17 and histone H1 in regulation of transcription of the glucocorticoid-sensitive MMTV gene.

Animals↗

PubMed1992

[A case of latent Addison's disease with hypogonadotropic hypogonadism and dwarfism].

A case of latent Addison's disease accompanied by hypogonadotropic hypogonadism and dwarfism is described. A 20-year-old man was admitted to our department complaining of short stature and immature development of the external genitalia. Pigmentation was most evident on the fingers and face. Endocrinologically, serum ACTH level was very high, and serum cortisol level was in the lower limit of the normal range. Serum aldosterone and adrenal androgen levels were below their normal ranges. Based on these clinical and laboratory findings, the patient was diagnosed as having latent Addison's disease. Serum LH did not respond to a bolus injection of LH-RH. However, after 3 days administration of LH-RH, the response of serum LH to a bolus injection of LH-RH was enhanced. Serum testosterone level was not increased after the administration of hCG. These findings suggested a hypothalamic cause for the hypogonadism. It was indicated that short stature was apparently caused by GH neurosecretory dysfunction, since nocturnal GH secretion was below that in normal males and the response of GH to the administration of arginine was normal. In regard to the thyroid function, the peak of serum TSH after a bolus injection of TRH was delayed compared with normal subjects, and although serum T4 level was high, the basal metabolic rate was very low. This suggests that there is tissue resistance to the elevated thyroid hormone.

Addison Disease↗