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Biomedical subjects

K Mizobuchi

Publications and source records attributed to K Mizobuchi.

At least 73 records · Page 4Linked to original sources
PubMed1989

Nucleotide sequence analysis of genes purH and purD involved in the de novo purine nucleotide biosynthesis of Escherichia coli.

5'-Phosphoribosylglycinamide synthetase (EC 6.3.4.13) and 5'-phosphoribosyl 5-aminoimidazole-4-carboxamide transformylase (EC 2.1.2.3) are enzymes involved in the de novo purine nucleotide synthesis and are encoded by purD and purH genes of Escherichia coli, respectively. A 3535-nucleotide sequence containing the purHD locus and the upstream region of the rrnE gene was determined. This sequence specifies two open reading frames, ORF-1 and ORF-2, encoding proteins with the expected Mr of 57,329 and 46,140, respectively. The plasmids carrying ORF-1 complemented not only the mutant cells defective in purH of E. coli but also the cells of Salmonella typhimurium lacking the activity of IMP cyclohydrolase (EC 3.5.4.10) which catalyzes the conversion of 5'-phosphoribosyl 5-formylaminoimidazole-4-carboxamide to IMP. The E. coli purH gene, therefore, specifies bifunctional 5'-phosphoribosyl 5-aminoimidazole-4-carboxamide transformylase-IMP cyclohydrolase. The plasmids carrying ORF-2 were able to complement the mutant cells defective in purD. Both purH and purD genes constitute a single operon and are coregulated in expression by purines as other purine genes are. A highly conserved 16-nucleotide sequence termed the PUR box (Watanabe, W., Sampei, G., Aiba, A., and Mizobuchi, K. (1989) J. Bacteriol. 171, 198-204; Tiedeman, A.A., Keyhani, J., Kamholz, J., Daum, H. A., III, Gots, J.S., and Smith, J.M. (1989) J. Bacteriol. 171, 205-212) was found in the control region of the purHD operon and compared with the sequences of the control regions of other purine operons.

Acyltransferases↗
PubMed1989

Identification and sequence analysis of Escherichia coli purE and purK genes encoding 5'-phosphoribosyl-5-amino-4-imidazole carboxylase for de novo purine biosynthesis.

It has been shown that the Escherichia coli purE locus specifying 5'-phosphoribosyl-5-amino-4-imidazole carboxylase in de novo purine nucleotide synthesis is divided into two cistrons. We cloned and determined a 2,449-nucleotide sequence including the purE locus. This sequence contains two overlapped open reading frames, ORF-18 and ORF-39, encoding proteins with molecular weights of 18,000 and 39,000, respectively. The purE mutations of CSH57A and DCSP22 were complemented by plasmids carrying ORF-18, while that of NK6051 was complemented by plasmids carrying ORF-39. Thus, the purE locus consists of two distinct genes, designated purE and purK for ORF-18 and ORF-39, respectively. These genes constitute a single operon. A highly conserved 16-nucleotide sequence, termed the PUR box, was found in the upstream region of purE by comparing the sequences of the purF and purMN operons. We also found three entire and one partial repetitive extragenic palindromic (REP) sequences in the downstream region of purK. Roles of the PUR box and REP sequences are discussed in relation to the genesis of the purEK operon.

Amino Acid Sequence↗
PubMed1989

[Primary intracranial T cell type malignant lymphoma: a case report].

Primary intracranial T cell type malignant lymphoma is extremely rare. Only 8 cases are reported in the literature so far. In this paper, a case with this type of malignant lymphoma is reported. A 41-year-old man was admitted because of abnormal behavior. Enhanced CT scan demonstrated high density mass and perifocal low-density area in the right frontal lobe, the right basal ganglia and the periventricular region. Specimen biopsied from right frontal lobe was submitted for histological examination. An immunohistochemical technique using monoclonal surface markers confirmed reactivity for LCA, MT-1, OKT-4 and OKT-8, while there was no reactivity for MB-1 and OKB-2. Pathological diagnosis was diffuse medium T cell type malignant lymphoma. Postoperatively, after 60 Gy irradiation, the tumor disappeared. There is no difference on CT findings between B cell type and T cell type malignant lymphoma.

Adult↗
PubMed1989

[A case of vacuolated meningioma].

A rare case of falx meningioma with extensive vacuolization was reported. A 57-year-old woman was admitted to Okayama University Hospital because of numbness in her left lower limb. A plain CT scan showed a hypodense mass in the right frontal region with marked enhancement after contrast medium injection. MRI on T1 weighted images showed low intense mass with the so-called "peritumoral band" of low intensity at the periphery of the mass. Angiogram showed a mass effect and a tumor stain fed by the right pericallosal artery and left middle meningeal artery. The mass was excised en bloc. Microscopic examination demonstrated tumor cells with varied sized vacuoles, which were mostly fat-negative, except for small islands with typical meningothelial cells in the periphery of the tumor. Ultrastructurally, there were two kinds of vacuole in the tumor cells. The smaller, round vacuoles were in the cytoplasm, while the larger ones were in the extracellular space. The cell processes had developed junctional complex, and numerous cytoplasmic filaments were evident. With these findings, this mass was diagnosed as vacuolated meningioma. It is important especially in frozen section not to misdiagnose the tumor as liposarcoma, chordoma, metastatic brain tumor and so on.

Cerebral Angiography↗
PubMed1988

Elastosis in meningioma. A case report and electron microscopic study.

A 55-year-old man underwent left frontoparietal craniotomy for total removal of a parasagittal meningioma. The tumor showed a predominant pattern of meningotheliomatous meningioma and a partial pattern of angiomatous, transitional and fibrous meningioma. A striking feature was the appearance of unusually numerous elastinophilic material in the intercellular stroma. We observed a process in which the progress of elastosis changed the appearance of meningotheliomatous meningioma to a hypocellular, and subsequently acellular fibroelastotic node. Three years after the first craniotomy, meningioma recurred at the same site. The recurrent tumor also showed the histological pattern of meningotheliomatous meningioma with stromal elastosis, as previously observed. This is the first report of a case of meningioma with stromal elastosis. The present case represents the first unequivocal demonstration of elastogenesis in meningioma.

Elastic Tissue↗
PubMed1988

Novel segregation patterns of infecting-mutant genotypes in plate complementation tests among amber mutants of bacteriophage BF23.

Amber mutants of bacteriophage BF23 were classified into two functional groups, types I and II, by the yields of the infecting-mutant genotypes in plate complementation tests. Type I mutants produced their genotypes at levels more than 20% of the total progeny phages, and type II mutants did so at levels of less than 5%. Comparison of the results of plate complementation tests with those of extract complementation tests revealed that all the type I mutants were defective in the tail formation, while most type II mutants were defective in the formation of either mature heads (type IIa) or both mature heads and tails (type IIb). Since in extract complementation tests the activated phages are always of genotypes corresponding to mutations defective in only the tail formation, the plate complementation test is comparable with the extract complementation test when judged on the basis of the yield of the mutant genotypes. Of 29 complementation groups, 8 type I, 14 type IIa, and 5 type IIb mutants were identified. Previously, amber mutations of BF23 were mapped on four genetic segments. These segments were ordered in one linkage map by crosses between deletion and amber mutants.

Coliphages↗
PubMed1988

Relationships among genes and gene products of bacteriophage BF23.

Twenty-five gene products of bacteriophage BF23 were identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and their functions were studied in relation to type I and II genes classified by means of genetic complementation tests. All the type I mutants were defective in the synthesis of a tail protein, L3. In addition, 4 type I gene products, L5 (gp21), L7 (gp20), L8 (gp29), and L9 (gp25), were identified as constituents of tails (gp21 denotes that a protein is a product of gene 21). Three type IIb mutants in genes 10, 14, and 19 diminished substantially the production of late proteins, including tail and head proteins, and the two other type IIb mutants in genes 1 and 2 were defective in the synthesis of both early and late proteins. Of 14 type IIa mutants, at least 6 were defective in phage DNA synthesis and 2 were defective in the synthesis of head proteins. The defect in the head donor activities of type IIa mutants in extract complementation tests was due to the failure of the formation of mature heads containing DNA. The above results support directly the results of the genetic characterization of BF23 genes.

Autoradiography↗
PubMed1988

Regulation of the temporal synthesis of proteins in bacteriophage BF23-infected cells.

Regulation of temporal synthesis of pre-early, early, and late proteins in bacteriophage BF23-infected cells has been studied by using five amber mutants defective in genes 1, 2, 10, 14, and 19. The synthesis of pre-early proteins is negatively regulated by the actions of gene 1, a pre-early gene. The switch from pre-early to early protein synthesis is mainly regulated by the second-step DNA transfer reaction, which is controlled by at least genes 1 and 2. Early proteins can be kinetically and genetically divided into two regulatory classes, designated Ea and Eb. The shutoff of Eb-early protein synthesis is associated with the turn-on of late protein synthesis. This step is controlled by genes 10, 14, and 19. Gene 10 also regulates negatively the synthesis of Ea-early proteins, indicating that this gene has a dual function in the regulation of early protein synthesis. The temporal synthesis of phage-encoded proteins is regulated mainly at the transcriptional level. Evidence is presented indicating that the host RNA polymerase is modified by the interaction with the gene products of genes 2, 10, and 14 (gp2, gp10, and gp14, respectively). gp2 interacts with the enzyme in the earlier stage of infection but is replaced by gp10 in the later stage. This exchange reaction depends on the presence of gp14 and gp19 and is related to the switch from Eb to late protein synthesis. Thus, the regulation of BF23 gene expression occurs in a coordinated manner throughout the development of this phage.

Autoradiography↗
PubMed1987

An immunohistochemical study on the distribution of glial fibrillary acidic protein, S-100 protein, neuron-specific enolase, and neurofilament in medulloblastomas.

In order to clarify the differentiation of medulloblastomas, the authors studied on the morphological features and immunohistochemical expression of glial fibrillary acidic protein (GFAP), S-100 protein, neuron-specific enolase (NSE), and neurofilament (NF) in 31 medulloblastomas. GFAP was detected only in a small number of tumor cells of 5 medulloblastomas; S-100 protein in both small tumor cells and some so-called spongioblastic cells in 16 medulloblastomas; NSE in the more abundant tumor cells and the matrix in 28 medulloblastomas; NF in a few tumor cells of 12 medulloblastomas; GFAP and NF in 2 medulloblastomas, but each of them in different tumor cells. These results suggest that medulloblastomas have a capacity of differentiation along neuronal and/or glial lines. The conventional morphological markers of differentiation in medulloblastomas such as spongioblastic cells and Homer Wright rosettes were not necessarily compatible with expression of immunohistochemical markers such as GFAP or NF. NSE and S-100 protein seem less valuable markers of differentiation because they were detected in both neuronal and glial elements. But NSE, which was observed in most medulloblastomas, might have a value as a marker for medulloblastomas.

Adolescent↗
PubMed1986

A case of cerebellar hamartoma suggesting abnormal cell migration.

A rare case of hamartoma of the left cerebellar hemisphere was recognized in an 11-month-old male infant whose mother had a history of unspecified medication in the early gestational period and had a difficult delivery. A notably large head and marked developmental disorders, like hypotonic cerebral palsy, were observed soon after birth. A computed tomogram revealed an iso-minimally enhanced large mass in the left cerebellar hemisphere, which deformed the fourth ventricle and compressed the right cerebellum, as well as moderate cerebral atrophy. Histologically, the border between the cerebellar cortex and this tumor was not apparent. The main tumor, located in the cerebellar white matter, was composed of numerous scattered Purkinje cell-like neurons and glial cells surrounded by abundant GFAP-positive matrix. The small part of the tumor, located near the choroid plexus, was composed of intensely proliferated capillaries such as in capillary hemangioma, and numerous fibrocytes, which were intermingled with several large Purkinje cell-like neurons and some with several large Purkinje cell-like neurons and some GFAP-positive glial cells. The cerebellar cortex showed a thin molecular layer with some residual external granular cells, a marked decrease of Purkinje cells and a moderate decrease in the internal granular layer, in which large Purkinje cell-like neurons were scattered. Purkinje cells and large Purkinje cell-like neurons scattered in the internal granular layer, cerebellar white matter and choroid plexus showed positive immunoreactivity for anti-Leu-4 monoclonal antibody, which is known to be a marker for Purkinje cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Biopsy↗
PubMed1986

Infantile myofibromatosis. Report of two cases.

Two cases of infantile myofibromatosis were presented. Case 1 was a 6-month-old girl with multiple nodular lesions in the left parietal bone, dermis of abdominal wall, chest wall, right upper arm, and bilateral femur. Case 2 was a 12-month-old girl with solitary nodular lesions in the left parietal bone having a tendency to enlarge. Histologically, these tumorous lesions consisted of broad bundles of well oriented spindle-shaped cells superficially resembling smooth muscle tissue. In electron microscopy, the constituent cells combined ultrastructural characteristics of both fibroblasts and smooth muscle cells., Immunoperoxidase method showed that anti-smooth muscle antibodies binded to the cytoplasm of the bundle forming cells. From these results, it may be concluded that the lesion consisted of pure proliferation of myofibroblasts, and its peculiar growth behavior was discussed, though the histogenesis still remains obscure.

Female↗
PubMed1984

Undifferentiated neuroectodermal tumors induced by human adenovirus type 31 in Syrian hamsters.

Human adenovirus type 31 was inoculated intraperitoneally into 18 and intracranially into 98 Syrian hamsters within 24 hours of birth. Intraperitoneal tumors developed multicentrically in 94.4%, 93 days on an average after virus inoculation, while brain tumors developed in 6.1%, 154 days. Intraperitoneal tumors primarily developed in the subserosal tissues and protruded into the peritoneal cavity. Some of the five enlarged brain tumors seemed to have extended from the paraventricular regions to the neighboring structures, and one microtumor was located in the subependymal layer. Twenty-six of the 98 hamsters inoculated with virus intracranially unexpectedly developed tumors in the subcutaneous tissue of the skull. Histological, immunohistochemical and electron microscopic studies revealed that the tumors which developed in the different sites had essentially the same features and were composed of undifferentiated small cells of primitive neuroectodermal nature. The incidence and the characteristics of the tumors were discussed in comparison with those of adenovirus type 12-induced tumors described previously.

Adenoviridae Infections↗
PubMed1984

[A case of clear cell sarcoma of tendons and aponeuroses with a large amount of melanin--malignant melanoma of the soft part].

We report a 62-year-old male with a clear cell sarcoma of tendons and aponeuroses arising in the area of the M. flexor carpi ulnaris. Grossly, the tumor had a black appearance. Light microscopic inspection showed a large amount of melanin. Electron microscopically, the tumor pigment was located within melanosomes. The possibility that the tumor represents a neural crest-derived melanotic tumor (malignant melanoma) of the soft part is discussed.

Adenocarcinoma↗
PubMed1983

An adult case with rhabdomyosarcoma of the liver.

An autopsy case of primary rhabdomyosarcoma of the liver in a 70-year-old man is described. The case could not be clinically differentiated from hepatocellular carcinoma. The tumor showed typical features of rhabdomyosarcoma; phosphotungstic acid hematoxylin (PTAH)-positive myofibrils and cross-striations were observed in the cytoplasm of highly plemorphic tumor cells.

Aged↗