Biomedical subjects

S Matsuda

Publications and source records attributed to S Matsuda.

At least 433 records · Page 24Linked to original sources

PubMed1992

Xenopus MAP kinase activator: identification and function as a key intermediate in the phosphorylation cascade.

MAP kinase is thought to play a pivotal role not only in the growth factor-stimulated signalling pathway but also in the M phase phosphorylation cascade downstream of MPF. MAP kinase is fully active only when both tyrosine and threonine/serine residues are phosphorylated. We have now identified and purified a Xenopus MAP kinase activator from mature oocytes that is able to induce activation and phosphorylation on tyrosine and threonine/serine residues of an inactive form of Xenopus MAP kinase. The Xenopus MAP kinase activator itself is a 45 kDa phosphoprotein and is inactivated by protein phosphatase 2A treatment in vitro. Microinjection of the purified activator into immature oocytes results in immediate activation of MAP kinase. Further experiments using microinjection as well as cell free extracts have shown that Xenopus MAP kinase activator is an intermediate between MPF and MAP kinase. Thus, MAP kinase activator plays a key role in the phosphorylation cascade.

Animals↗

PubMed1992

Xenopus MAP kinase activator is a serine/threonine/tyrosine kinase activated by threonine phosphorylation.

Xenopus MAP kinase activator, a 45 kDa protein, has been shown to function as a direct upstream factor sufficient for full activation and both tyrosine and serine/threonine phosphorylation of inactive MAP kinase. We have now shown by using an anti-MAP kinase activator antiserum that MAP kinase activator is ubiquitous in tissues and is regulated post-translationally. Activation of MAP kinase activator is correlated precisely with its threonine phosphorylation during the oocyte maturation process. It is a key question whether MAP kinase activator is a kinase or not. We have shown that Xenopus MAP kinase activator purified from mature oocytes is capable of undergoing autophosphorylation on serine, threonine and tyrosine residues. Dephosphorylation of purified activator by protein phosphatase 2A treatment inactivates its autophosphorylation activity as well as its activator activity. Thus, Xenopus MAP kinase activator is a protein kinase with specificity for both serine/threonine and tyrosine. Partial protein sequencing of purified activator indicates that it contains a sequence homologous to kinase subdomains VI and VII of two yeast protein kinases, STE7 and byrl.

Amino Acid Sequence↗

PubMed1992

Three-dimensional crystal structure of recombinant murine interferon-beta.

The crystal structure of recombinant murine interferon-beta (IFN-beta) has been solved by the multiple isomorphous replacement method and refined to an R-factor of 20.5% against 2.6 A X-ray diffraction data. The structure shows a variant of the alpha-helix bundle with a new chain-folding topology, which seems to represent a basic structural framework of all the IFN-alpha and IFN-beta molecules belonging to the type I family. Functionally important segments of the polypeptide chain, as implied through numerous gene manipulation studies carried out so far, are spatially clustered indicating the binding site(s) to the receptor(s). Comparison of the present structure with those of other alpha-helical cytokine proteins, including porcine growth hormone, interleukin 2 and interferon gamma, indicated either a topological similarity in chain folding or a similar spatial arrangement of the alpha-helices.

Amino Acid Sequence↗

PubMed1992

Immuno-electron-microscopic localization of basic fibroblast growth factor in the dystrophic mdx mouse masseter muscle.

The localization of basic fibroblast growth factor (bFGF)-like immunoreactivity in the masseter muscle of dystrophic mdx mice on postnatal day 28 was investigated by immunoblot analysis and electron microscopy. Crude homogenate of the masseter muscle, when subjected to immunoblotting with a bFGF antiserum, exhibited a main band with the same molecular weight (18 kDa) as bovine bFGF. By electron microscopy, bFGF immunoreactivity was detected in small regenerating myocytes; the smaller cells were the premature myocytes, the most intense staining was the immunoreactivity within the cytoplasm. Putative precursors of the muscle cells with a few myofilaments, which were most intensely labeled with anti-bFGF, contacted each other and possibly developed into multinucleated myocytes through cell fusion. Mature myocytes with densely packed myofilaments and peripherally located nuclei did not exhibit bFGF immunoreactivity; they formed myoneural junctions with motor nerve endings immunoreactive for bFGF. Early differentiating myocytes with intense bFGF-like immunoreactivity did not make contact with immunoreactive nerve terminals. Degenerating large myocytes with a limited number of distorted and/or disrupted myofilaments exhibited electron-dense deposits in the cristae of mitochondria; these deposits were not abolished by immunoadsorption control experiments. Thus, the cell-size-dependent decrease in bFGF immunoreactivity in regenerating but not in degenerating myocytes provides a morphological basis for an autoregulatory role of bFGF in muscle regeneration. This study suggests that neuronal bFGF is not involved in initial muscle regeneration in the dystrophic mdx mouse.

Animals↗

PubMed1992

Constitutive expression of the nef gene suppresses human immunodeficiency virus type 1 (HIV-1) replication in monocytic cell lines.

In order to study the effect of nef gene expression on viral replication in monocytic cells, we established monocytic (U937 and THP-1) cell transfectants constitutively expressing the human immunodeficiency virus type 1 nef gene. We constructed a plasmid expressing the nef gene derived from an infectious clone, NL432, under the control of SR alpha promoter which can drive a high level of gene expression. We found suppressed viral replication in nef-expressing monocytic cells, although a negative effect of nef was observed, with some variation depending on the virus strain and the cell. We also observed that the expression of the surface CD4 molecule is inversely related to the expression of the nef gene, especially in the U937 transfectants. These results indicate that the suppression of viral replication and the down-modulation of CD4 molecule by nef gene expression occur in monocytic cell lines as in T cell lines.

CD4 Antigens↗

PubMed1992

Basic fibroblast growth factor-like immunoreactivity in Purkinje cells of the rat cerebellum.

An antiserum against basic fibroblast growth factor was characterized by immunoblot experiments and used to investigate immunohistochemically the projection fields and fine structures of basic fibroblast growth factor-containing cerebellar Purkinje cells. The antiserum demonstrated clearly purified basic fibroblast growth factor and basic fibroblast growth factor-like molecules of the same molecular weight in homogenates of the adult rat cerebellum. Light and electron microscopic immunohistochemistry revealed that a large number of Purkinje cells, if not all, send immunoreactive dendrites to the molecular layer and basic fibroblast growth factor-containing axons to the deep cerebellar and lateral vestibular nuclei, where basic fibroblast growth factor nerve terminals form synapses with the soma and dendrites of neurons labeled weakly with basic fibroblast growth factor. Nerve cells with basic fibroblast growth factor had immunoreaction deposits mainly in free ribosomes, those attached to the endoplasmic reticulum and in the nuclear euchromatin. These findings suggest that basic fibroblast growth factor is present in cerebellar Purkinje cells and undergoes two modes of transport, one to axon terminals and the other to nuclear euchromatin, known as the RNA transcription zone.

Animals↗

PubMed1992

Tongue cancer treated with irradiation: assessment with MR imaging.

We examined the usefulness of MRI in differentiating post-radiation scar tissue from the residual tumour. Ten consecutive patients who underwent MR imaging before and after radiation therapy were assessed prospectively. T1- and T2-weighted images using a 1.5 unit were obtained in 10 patients (3 T1, 6 T2, 1 T3) at 1 week before irradiation, and 2 weeks, 2 months, 4 months, 6 months and every 6 months thereafter following completion of radiation. Although all T2 and T3 tumours demonstrated high signal intensity compared to muscle on T2-weighted images, the T1 tumour could be demonstrated in only one of three patients. Six patients in whom the primary tumour clinically disappeared demonstrated low signal intensity on T2-weighted images until 4 months after completion of radiation therapy (range 1 week to 4 months). This study suggests that MRI can detect primary tumours larger than T2 (2 cm), and may be useful in assessing the effectiveness of therapy for tongue cancer.

Adult↗

PubMed1992

Seasonality of preterm births in Japan.

Seasonal variations in the proportion of preterm births in Japan from January 1979 to December 1983 are analysed using a traditional method of time-series analysis, which divides the variation in a series into trend, seasonal variation, other cyclic change, and remaining irregular fluctuations. It is shown that the proportion of preterm births in Japan have a clear seasonal periodicity with two peaks in summer and winter. Analysis of seasonality by period of gestation shows that interesting differences in kurtosis and skewness exist between summer and winter, i.e. the summer increase in preterm births was characterized by an increase of skewness which means an extension of the lower part of the distribution. On the other hand, the winter increase was characterized by a decrease of kurtosis which corresponds to a flat-topped distribution. This result suggests that causes of preterm births might be different between the two seasons. Theoretical simulations based on actual birth data in Japan over the period, are carried out to examine how season of conception could influence seasonal variations in the proportion of preterm births. Results show that, at least for first births, seasonality in conception rates could be one explanatory factor for the observed seasonal variation in proportions of preterm births. Another analysis reveals that conception in May and June are more likely to result in preterm births in Japan.

Epidemiology↗

PubMed1992

BUN/Cr ratio as an index of gastrointestinal bleeding mass in children.

Determining the site and severity of blood loss is important in the management of children with gastrointestinal (GI) bleeding. Blood urea nitrogen (BUN) and serum creatinine (Cr) were measured on the day of hospitalization and the ratio of BUN/Cr was calculated in 11 children with 16 episodes of upper GI bleeding and 49 with lower GI bleeding. There was a significant difference between the two GI bleeding groups with regard to BUN/Cr ratio (p less than 0.001). When the ratio was 30 or above, the specificity of upper GI bleeding was 98% with a sensitivity of 68.8%. A linear relationship was found between the BUN/Cr ratio and delta Hb (delta Hb = 0.08 x BUN/Cr +/- 0.8 g/dl) for bleeding originating from the upper GI tract. This study confirms that measurement of the BUN/Cr ratio is useful for localizing the source of bleeding to the upper GI tract and also demonstrates its usefulness as an estimation of the severity of blood loss from the upper GI tract.

Adolescent↗

PubMed1992

Detection of the ligand activity of the c-erbB-2 protein in calf serum.

We established NIH3T3 derivatives in which wild-type c-erbB-2 or activated c-erbB-2 having a point mutation in the sequence coding for the transmembrane domain was expressed. These cell lines were termed RC and A4, respectively. A4 cells but not RC or NIH3T3 cells grew even in the presence of a low concentration (0.05%) of calf serum (CS), although the rate of their proliferation was low. In media containing 0.1% CS, both A4 cells and RC cells but not NIH3T3 cells could proliferate. Furthermore, RC cells induced foci formation when cultured in media containing 0.5% and 5% CS, while growth of the parental NIH3T3 cells was contact-inhibited under these conditions. These data suggest the presence of a factor(s) which activates protein-tyrosine kinase activity of the c-erbB-2 protein. In fact, the c-erbB-2 protein prepared from RC cells showed CS-dependent protein-tyrosine kinase activity when assayed in membrane fractions.

3T3 Cells↗

PubMed1992

Basic fibroblast growth factor ameliorates rotational behavior of substantia nigral-transplanted rats with lesions of the dopaminergic nigrostriatal neurons.

Basic fibroblast growth factor (bFGF) was injected with dissociated substantia nigral cells into the striatum of rats prepared by unilateral lesion of the nigrostriatal pathway with 6-hydroxydopamine. The transplanted cells with 5 and 50 ng bFGF reduced the apomorphine-induced rotations by 40 and 30%, respectively, while the decrement of rotations was only 15% in the grafted control without bFGF. Immunohistochemical staining with anti-tyrosine hydroxylase antibody showed that bFGF also tended to increase the number of grafted catecholaminergic neurons along the tracts. In the case of 50 ng bFGF treatment but not 0 or 5 ng bFGF treatment, however, severe gliosis was detected along the grafted region by staining of anti-glial fibrillary acidic protein antibody. These immunohistochemical studies suggested that high-dose bFGF induced extensive gliosis, which might affect the survival of the grafted neurons.

Animals↗

PubMed1992

[Seasonal variation of mean birth weight in Okinawa].

Seasonal variation of mean birth weight in Okinawa was examined by a traditional time-series analysis, which decomposed the variation in a series into trends, seasonal variations, other cyclic changes, and remaining irregular fluctuations, based on the data in Vital Statistics from January 1974 to December 1983. The seasonal index of mean birth weight showed a peak in winter to early spring and a bottom in summer with statistical significance. Previous reports have revealed that the gestational period is the most important factor associated with birth weight. Therefore, we carried out the time series analysis for the mean gestational period but could not observe seasonal periodicity in it. On the other hand, mean birth weight at 40 gestational weeks was significantly lower in summer. These results suggest that factors other than the gestational period, such as infectious diseases, nutritional conditions and so on, might play important role in seasonal variations of mean birth weight in Okinawa.

Birth Weight↗

PubMed1992

[Seasonal variation of mean birth weight and births in Nagano Prefecture].

Seasonal variation of mean birth weight in Nagano Prefecture was examined by a traditional time series analysis, which decomposes the variation in a series into trend, seasonal variation, other cyclic changes, and remaining irregular fluctuations, based on the data in Vital Statistics from January 1974 to December 1983. The seasonal index of mean birth weight showed a unimodal pattern with a peak in June for males, and a bimodal pattern with peaks in spring and autumn in females with statistical significance. Previous reports have revealed that gestational period is the most important factor associated with birth weight. Therefore, we carried out time series analysis for the mean gestational period and observed an apparent seasonal periodicity, which showed a unimodal pattern with a bottom in winter for both sexes and parities. According to the results of statistical testing of the degree of coincidence between two time series, the time series of mean birth weight and that of mean gestational periods showed statistically significant coincidences in their monthly variations for multiparae. On the other hand, mean birth weight at 40 gestational weeks, which reflects the intrauterine growth, did not show seasonality. These results suggest that seasonality in gestational periods might play an important role in creating seasonal variations of mean birth weight in Nagano Prefecture. The average daily number of births by month also showed apparent seasonalities both for primiparae and multiparae. Primiparae showed a bimodal pattern with peaks in February and August, while multiparae showed a unimodal pattern with a peak in May and a bottom in November. It has been said that the seasonality in marriage is one of important factors associated with seasonal variation in births.(ABSTRACT TRUNCATED AT 250 WORDS)

Birth Rate↗

PubMed1992

Molecular cloning of feline interferon cDNA by direct expression.

A cDNA sequence coding for feline interferon has been cloned for the first time by screening a cDNA library constructed using Okayama-Berg vector and mRNA derived from the feline cells (LSA-I) induced by TPA (12-o-tetradecanoylphorbor 13-acetate) for the ability of transient expression to produce feline interferon in COS1 monkey cells. The amino acid sequence, deduced from the nucleotide sequence by comparing it with the sequences of other mammalian IFNs, consists of 171 amino acids with 6 cysteins and an N-glycosylation site at the amino acid position 79, and has about 60% homology to human IFN alpha 1. The interferon was partially purified through Blue Sepharose, and its molecular weight was estimated to be 2.4 x 10(4). The antiviral activity was acid stable, and glycosylation was suggested.

Amino Acid Sequence↗

PubMed1992

[Occlusion-reperfusion model of cerebral ischemia in Fischer 344 rats].

The effect of transient cerebral ischemia (from 15 to 180 min) by bilateral carotid arterial occlusion on postischemic mortality rate and the signs of nervous disorder in Fischer 344 rat was studied. Total mortality rate was 40 to 60% during 72 hr of reperfusion following 2 hr ischemia. Postischemic mortality rate did not vary distinctly with 10, 20 and 40 weeks-old.

Animals↗

PubMed1992

The immunomodulatory role of IFN-alpha or maltose-stabilized IFN-alpha on T-cell activation.

The effects of human interferon-alpha (IFN-alpha) or maltose-stabilized IFN-alpha (MS-IFN-alpha) on IL-2 production by PHA- or anti-CD3 mAb-stimulated MOLT 16 cells, a human leukemic T cell line, were studied. MS-IFN-alpha is an IFN-alpha-containing powder in which maltose was used as an excipient, and has been shown to have a positive effect on human immunodeficiency virus (HIV)-infected patients. In this study, MS-IFN-alpha powder was dissolved in a culture medium and used for the experiments. IL-2 production by PHA- or anti-CD3 mAb-stimulated MOLT 16 cells was augmented by coculturing with IFN-alpha or MS-IFN-alpha. The augmentation of IL-2 production by IFN-alpha or MS-IFN-alpha was completely abrogated by rabbit anti-IFN-alpha antibody. We have previously shown that IL-2 production by PHA-stimulated MOLT 16 cells is augmented by coculturing with IL-1. Furthermore, IL-2 production by PHA-stimulated MOLT 16 cells was also augmented by human TNF-alpha in a dose-dependent manner. The TNF-alpha-induced augmentation was completely abrogated by rabbit anti-TNF-alpha antibody. Interestingly, both IFN-alpha and MS-IFN-alpha synergized with rIL-1 alpha or TNF-alpha resulting in IL-2 production being augmented far more effectively than either cytokine alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗

PubMed1992

[Study of liver function in babies with atopic dermatitis by using 13C-methacetin breath test].

We measured serum GOT levels in babies with atopic dermatitis and food allergy. Two hundred and fourteen babies (133 male, 18 female, under 2 years of age) who first visited the Department of Allergy in the National Children's Hospital were examined. Their serum GOT levels were higher than normal; the younger they were, the higher the serum GOT levels were. We carried out the 13-methacetin breath test (MBT) on 11 babies with atopic dermatitis and high serum GOT levels as well as 5 normal babies to estimate their hepatic microsomal function. 13C-methacetin was administered (0.5 mg/kg) orally, and breath was collected at 30 minutes before and immediately before administration. After administration it was collected at 15 minute intervals for the first hour and 45 minute intervals for 90 consecutive minutes afterwards. The level of 13CO2 in their breath was determined with a mass spectrometer. The peak level of 13CO2 excretion (%dose/hr) in the atopic babies with high serum GOT levels was lower and the time required for 13CO2 excretion to reach its maximum level was longer than in normal babies. Also their 13CO2 clearance rate (%/hr) was lower. These results suggested that there was some relationship between atopic dermatitis and liver dysfunction in babies.

Acetamides↗

PubMed1992

[Prevalence and pathogenesis of iron deficiency in Japanese women (1981-1991)].

Iron deficiency anemia is the most prevalent among form of anemia in the world. In Japan, there is no overall report concerning prevalence and pathogenesis of iron deficiency. We estimated the prevalence of iron deficiency from the results of a survey of 3,015 Japanese women. The reference range for hemoglobin was derived from the average value of subjects with normal iron status (> or = 16% of transferrin saturation and > or = 12 ng/ml of serum ferritin). Using these reference standards, the prevalence of iron deficiency anemia, latent iron deficiency, storage iron deficiency, normal and others were 8.5%, 8.0%, 33.4%, 43.6% and 6.5%, respectively. The prevalence of iron deficiency anemia increased beginning in early lower teen girls, was highest in high teen-girls and, young women and decreased in elderly women. In elderly women, the cause of iron deficiency was often obvious associated with anemia of chronic disorders. The strategy for iron deficiency was discussed concerning iron fortification, mega-ingestion of vitamin C and low dose administration of iron tablets in the higher incidence group.

Adolescent↗