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Biomedical subjects

T Shibata

Publications and source records attributed to T Shibata.

At least 865 records · Page 48Linked to original sources
PubMed1988

Adrenocortical carcinoma in infancy. Report of a case with immunohistochemical and ultrastructural studies.

A case of adrenocortical carcinoma associated with congenital heart defect in a 6-month-old Japanese girl is reported. A fist-sized tumor was incidentally noted in the right hypochondrium upon admission for cardiac surgery. No clinical endocrinopathy was evident in this case. The resected tumor was encapsulated with smooth surface and no invasion to adjacent tissues or organs was observed. Histologically, the tumor was composed of small cells with granular or clear cytoplasm, and occasional giant cells with single or multiple nuclei. By electron microscopy, the tumor cells showed various nuclear contours with distinct nucleoli and had a moderate amount of cytoplasm containing abundant rough endoplasmic reticulum and mitochondria with variable-sized electron-dense granules. Intercellular desmosome-like junctions were observed in some tumor cells. Immunohistochemically, the tumor cells contained granules positive for estriol, progesterone and cortisol. These morphological findings including electron microscopic features suggested that the tumor cells had a malignant character.

Adrenal Cortex Neoplasms↗
PubMed1988

[Atlanto-axial interspinous articulation--a histological study].

Three cases of atlanto-axial interspinous articulation (AIA) were reported. In a case, the articulating C1 posterior arch and C2 spinal process were removed en bloc during surgery. In an other case, articulating parts of C1 and C2 arches were excised by chisel. These had facets with glistening smooth surfaces and were consisted of fibrocartilage histologically. The facets were connected by a membrane containing the synovial layer, loose connective tissue layer with small vessels and the dense fibrous layer. With review of X-ray findings of present cases and cases reported in the literature, the AIA was classified into (1) simple type and (2) hyperplastic type. It was stressed that the hyperplastic type of AIA can produce definite cord compression.

Adult↗
PubMed1988

Use of silicone elastomer for improvement of intestinal clamp.

An intestinal clamp was improved by application of a silicone elastomer measuring 3, 4 and 5 millimeters in thickness to the nip surfaces to reduce nip force or to make pressure distribution more uniform. For the 1 kilogram weight, the output from the pressure sensor, which was placed on the blade, was decreased as the thickness of the silicone elastomer was increased. Pressures loaded on central and marginal regions of the large intestine were more than seven times greater than that on the mesenteric region with use of a conventional clamp. In contrast, pressures on all of the mesenteric, central and marginal regions were relatively low and uniform with use of clamps equipped with silicone elastomer. These results indicate that the clamp equipped with the silicone elastomer damages tissues only to a small extent because of the dispersion effect of the pressure and the uniformity of the pressure distribution.

Anastomosis, Surgical↗
PubMed1987

rec-A protein-promoted recombination reaction consists of two independent processes, homologous matching and processive unwinding. A study involving an anti-rec-A protein-monoclonal IgG.

recA protein promotes the formation and processing of joint molecules of homologous double-stranded DNA and single-stranded DNA. We studied the effects of an anti-recA protein monoclonal IgG (ARM193) on two processes carried out by the recA protein. The homologous matching, i.e. pairing of double-stranded DNA and single-stranded DNA by forming intermolecular base-pairing at homologous regions was found to occur even in the presence of an excess amount of antibody ARM193. On the other hand, processive unwinding, i.e. the propagation of the unwinding of double-stranded DNA through a processive reaction of recA protein, which occurs even in the absence of single-stranded DNA, was found to be very sensitive to the inhibition by antibody ARM193. Therefore, we conclude that homologous matching and processive unwinding are independent of each other. Analysis of the effect of antibody ARM193 on the various activities of recA protein suggests that the entire reaction of the formation of joint molecules and their processing can be rationalized in terms of these two underlying processes, homologous matching and processive unwinding. This analysis also suggests that homologous matching seems to require only the binding itself of active units of recA protein to single-stranded DNA but not necessarily either the cooperativity of the protein or unwinding.

Animals↗
PubMed1987

Intrinsic DNA-dependent ATPase activity of reverse gyrase.

Reverse gyrase is a type I DNA topoisomerase that promotes positive supercoiling of closed-circular double-stranded DNA through an ATP-dependent reaction, and it was purified from an archaebacterium, Sulfolobus. When ATP is replaced by UTP, GTP, or CTP, this enzyme just relaxes the negatively supercoiled closed-circular double-stranded DNA. We found that reverse gyrase hydrolyzes ATP through a double-stranded DNA-dependent reaction. The superhelicity of the DNA did not affect the ATPase activity. However, reverse gyrase does not hydrolyze UTP, GTP, or CTP. Therefore, any of the four nucleotide 5'-triphosphates acts as an effector for the topoisomerase activity of reverse gyrase, but only ATP supports the positive supercoiling of closed-circular double-stranded DNA, through the energy released on its hydrolysis. Single-stranded DNA was a much more potent cofactor for the ATPase activity of the enzyme than double-stranded DNA, and it acted as a potent inhibitor for the topoisomerase activity on double-stranded DNA. These results indicate that reverse gyrase has higher affinity to single-stranded DNA than to double-stranded DNA, which suggests a cellular function of the enzyme.

Adenosine Triphosphatases↗
PubMed1987

Molecular cloning and sequence analysis of cDNAs encoding porcine kidney D-amino acid oxidase.

Complementary DNAs encoding D-amino acid oxidase (EC 1.4.3.3, DAO), one of the principal and characteristic enzymes of the peroxisomes of porcine kidney, have been isolated from the porcine kidney cDNA library by hybridization with synthetic oligonucleotide probes corresponding to the partial amino acid sequences. Analysis of the nucleotide sequences of two clones revealed a complete 3211-nucleotide sequence with a 5'-terminal untranslated region of 198 nucleotides, 1041 nucleotides of an open reading frame that encoded 347 amino acids, and a 3'-terminal untranslated region of 1972 nucleotides. The deduced amino acid sequence was completely identical with the reported sequence of the mature enzyme [Ronchi, S., Minchiotti, L., Galliano, M., Curti, B., Swenson, R. P., Williams, C. H. J., & Massey, V. (1982) J. Biol. Chem. 257, 8824-8834]. These results indicate that the primary translation product does not contain a signal peptide at its amino-terminal region for its translocation into peroxisomes. RNA blot hybridization analysis suggests that porcine kidney D-amino acid oxidase is encoded by three mRNAs that differ in size: 3.3, 2.7, and 1.5 kilobases. Comparison of the sequences of the two cDNA clones revealed that multiple polyadenylation signal sequences (ATTAAA and AACAAA) are present in the 3'-untranslated region, making the different mRNA species. The efficiency of 3' processing of the RNA was quite different between the two signal sequences ATTAAA and AACAAA. Southern blot analysis showed the presence of a unique gene for D-amino acid oxidase in the porcine genome.

Amino Acid Sequence↗
PubMed1987

The use of the monoclonal antibody Ki-67 in determination of the growth fraction in pediatric brain tumors.

Using the monoclonal antibody Ki-67, proliferating cells were demonstrated immunohistochemically in 16 tumors of the nervous system in children, and these findings compared with those in 44 adult tumors. The antibody, which reacts with a nuclear protein expressed during the G1, S, G2, and M phases of the cell cycle, was demonstrated in frozen (13 cases) or smear (3 cases) sections using the peroxidase-antiperoxidase method. The percentage of stained tumor cells in children was in general agreement with the histological grade, ranging from 0.2% in a schwannoma to 12.4% in a juvenile type of glioblastoma. In a medulloblastoma, the fraction of labeled nuclei was 10.2%. In malignant gliomas of children, the percentage of stained cells did not differ from that in adult tumors. However, some cases demonstrated an unusually higher number of positive cells associated with higher cellularity than did adult tumors; this is in agreement with the content of small immature tumor cells in many pediatric tumors. The use of Ki-67 staining could become an important additional criterion for predicting the biologic behavior of nervous system neoplasms in children.

Adolescent↗
PubMed1987

Chronic pancreatitis at early age of onset presenting interesting findings through endoscopic retrograde pancreatography and chemical analysis of nonopaque pancreatic concretion.

This case concerns a 20-year-old male patient with an approximate 10-year history of recurrent and severe abdominal pain radiating to the back. Endoscopic retrograde cholangiopancreatography revealed a short obstructing stenosis of the main pancreatic duct in the head of the pancreas, marked and tortuous dilatation of the prestenotic portion of the main pancreatic duct and its side branches, and a filling defect in the side branch in the body of the gland. Pancreaticojejunostomy was performed to induce decompression of the pancreatic duct. Histology of the pancreas showed advanced chronic pancreatitis. Three nonopaque concretions were obtained at operation. The largest one, which was milky white in appearance and elastic and soft in consistency, proved to be made up of protein. The concretion was rich in acidic amino acids, but poor in basic or aromatic residues. The molar composition of amino acids in the concretion was, in decreasing order, aspartic acid, serine, valine, glycine, and glutamic acid. Powder x-ray diffractometry revealed no crystalline structures.

Adult↗
PubMed1987

The monoclonal antibody Ki-67 as a marker for proliferating cells in stereotactic biopsies of brain tumours.

The monoclonal antibody Ki-67 has been tested as a marker of proliferating cells in 52 stereotactic brain tumour biopsies. The antibody reacts with a nuclear protein expressed in G1,S, G2n and M-phases of the cell cycle. Using the immunoperoxidase technique on squash preparations the percentage of Ki-67 positive cells was determined as a fraction of the total number of tumour cells present. This Ki-67 index was in close correlation with the histological grade. Highest values were found in a pineal germinoma (46.3%) and in 3 primary cerebral non-Hodgkin lymphomas (mean 39.5%). Among the gliomas, the highest fraction of proliferating cells was seen in 2 anaplastic paediatric brain stem gliomas (mean 17.4%) and in an anaplastic ependymoma (12.5%). Anaplastic astrocytomas and glioblastomas varied considerably with mean values of 9.5% and 8%, respectively. To some extent this variability may reflect tumour heterogeneity which is more likely to manifest in small stereotactic samples than in large tissue specimens obtained during open surgery. Pilocytic astrocytomas, mixed gliomas and fibrillary astrocytomas had moderate to low percentages. Ki-67 staining of squash preparations can easily be performed on a routine basis and is, in our experience, superior to frozen sections. This method allows the determination of the growth fraction of an individual tumour and could become an important additional criterion for the decision among alternative and potentially harmful therapeutic regimens.

Antibodies, Monoclonal↗
PubMed1987

Dissolution of pancreatic stones by oral trimethadione in a dog experimental model.

Experiments were conducted to develop a dissolution therapy for human pancreatic calculi in a dog experimental model of pancreatic calculi surgically prepared. On plain x-ray films of the abdomen, pancreatic calculi appeared in 19 of 39 dogs within 12 mo after operation. The antiepileptic agent trimethadione was given orally to 13 dogs at a dose of 1.0-1.5 g daily. Pancreatic calculi disappeared in 13 of 15 observations. The scanning electron microscopy, the elemental analysis, and the powder x-ray diffractometry of pancreatic calculi in this model revealed that the calculi closely resembled human pancreatic calculi, consisting mainly of a calcite of calcium carbonate. There was no histologic finding suggesting drug toxicity in the liver, the kidney, and the blood. Pancreatic calculi in 6 control dogs without the treatment neither disappeared nor diminished spontaneously. The oral treatment with trimethadione may have potential for dissolving human pancreatic calculi.

Administration, Oral↗
PubMed1987

Polyamine biosynthesis is necessary for interleukin-2-dependent proliferation but not for interleukin-2 production or high-affinity interleukin-2 receptor expression.

DL-alpha-Difluoromethylornithine (DFMO), a specific inhibitor of ornithine decarboxylase [EC 4.1.1.17] (ODC), inhibited concanavalin A-induced proliferation of splenic mononuclear cells (SMNC). The inhibition was not reversed by interleukin-2 (IL-2) addition. Although DFMO did not affect the production of IL-2 or the expression of high-affinity IL-2 receptor, IL-2-dependent proliferation of SMNC was inhibited by DFMO, and the inhibition was reversed by exogenous putrescine. The inhibition of IL-2-dependent DNA synthesis appeared to be related to the decrease in intracellular polyamines. When the proliferation of SMNC was induced by IL-2, ODC activity was also increased. A similar result was obtained in the proliferation of an IL-2-dependent T cell line, CTLL. The time course of ODC induction was similar to that of IL-2 production by concanavalin A-stimulated SMNC. These results indicate that polyamine biosynthesis is necessary for IL-2-dependent proliferation, but not for IL-2 production or IL-2 receptor expression.

Animals↗
PubMed1987

Identification of a temperature-resistant bacteriophage phi X174 mutant.

Bacteriophage phi X174am3trD, a high temperature-resistant mutant of phi X174am3, was 10(4) times more stable than phi X174am3 as judged by its survival ratio after heat treatment at 54 degrees C for 120 min. Complementation tests showed an involvement of gene G. Sequence analysis of this gene revealed three mutation sites, one transition and two insertions. The first was a silent mutation and the others brought about a change in one amino acid and an addition of another, respectively, in the gene G protein. These changes in amino acid sequence resulted in a change in the secondary structure of the protein. A beta-turn region in part of the gene G protein of phi X174am3 was changed to an alpha-helix in phi X174am3trD. These results indicate that the temperature resistance of phi X174am3trD may be caused by elevated hydrophobicity in the mutated region or by strong interaction between the mutated gene G protein and other capsid proteins.

Amino Acid Sequence↗