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Biomedical subjects

T Kitamura

Publications and source records attributed to T Kitamura.

At least 19 recordsLinked to original sources

Reactive proliferation of astrocytes studied by immunohistochemistry for proliferating cell nuclear antigen.

Astrocyte proliferation in the stab-wounded cerebral cortex of mice was studied using double immunohistochemistry for proliferating cell nuclear antigen (PCNA) and glial fibrillary acidic protein (GFAP). The number of GFAP-positive astrocytes increased markedly from day 0.5 to day 3 after stab wounding. Some GFAP-positive astrocytes in the immediate vicinity of the wound were found to be positive for PCNA. However, the maximum number of these double positive astrocytes was only 5-6% of the number of GFAP-positive astrocytes. This maximum value was observed on days 2.5 and 3. The present study revealed that astrocytes are able to reactively express PCNA, an intrinsic marker of DNA replication. On the other hand, it is suggested that the proliferation of astrocytes in the wounded cerebral cortex is limited, in contrast with their marked reactive up-regulation of GFAP.

Animals

Glutamine synthetase immunoreactivity in two types of mouse brain glial cells.

The localization and distribution of glutamine synthetase (GS) in the adult mouse brain were studied by immunohistochemistry. GS immunoreactivity was found in two morphologically distinct types of glial cells apart from Bergmann glia, one asteroid and the other ovoid. The light and electron microscopic features of the GS-positive asteroid and ovoid cells were well consistent with those of astrocytes and oligodendrocytes, respectively. The GS-positive asteroid cells were present in the hippocampus, cerebral cortex, neostriatum, and cerebellar granular layer, where many synapse receptors for excitatory amino acids such as glutamate are densely distributed. Weakly GS-positive asteroid cells were also scattered in the white matter. The GS-positive ovoid cells were present throughout the gray matter regions of the brain except for the hippocampus, and they were the predominant type of GS-positive cells in the thalamus and brainstem gray matter where excitatory amino acid receptors are relatively sparse. No GS-positive ovoid cells were found in the white matter. These results suggest that, in the mouse brain, GS is localized in oligodendrocytes of the gray matter and in astrocytes. These two types of GS-positive glial cells may play different roles in the metabolism of glutamate.

Animals

Functional reconstitution of the human interleukin-3 receptor.

The high-affinity receptors for human interleukin-3 (IL-3), GM-CSF, and IL-5 are composed of alpha and beta subunits. The alpha subunits are primary ligand binding proteins specific for each ligand, whereas the three human receptors share a common beta subunit (beta c). In contrast to humans mice have two closely related genes, AIC2A and AIC2B, which are homologous to human beta c. The AIC2A gene encodes a low-affinity murine IL-3 binding protein, and the AIC2B protein is the beta subunit shared between murine GM-CSF receptors (mGMR) and IL-5 receptors (mIL-5R). To examine the function of these receptor components, we established various stable transfectants of murine IL-2-dependent CTLL-2 cells. CTLL-2 transfectants expressing both the alpha and beta subunits of the human IL-3 receptor (hIL-3R) proliferated in response to physiologic concentrations of hIL-3. Coexpression of hIL-3R alpha with AIC2B but not with AIC2A in CTLL-2 cells conferred a growth response to hIL-3. Although CTLL-2 transfectants expressing hIL-3R alpha alone did not proliferate in the presence of hIL-3, hIL-3-responsive sublines were repeatedly isolated. These sublines expressed endogenous AIC2B but not AIC2A. These results indicate that human beta c is essential for hIL-3 signaling and that AIC2B is a murine equivalent of human beta c. We also showed that hIL-3 and hGM-CSF induced tyrosine phosphorylation of several proteins in CTLL transfectants, similar to those observed in human factor-dependent TF-1 cells stimulated with hIL-3 and hGM-CSF.

Animals

Intrahepatic venous and portal venous aneurysms examined by color Doppler flow imaging.

Thirteen cases with liver cystic lesions, which were suspected to communicate with intrahepatic vessels on the basis of ordinary sonography, were examined by color Doppler flow imaging. By this method, blood flow within the cystic lesion was detected in 5 of these cases, and the communication to the intrahepatic vessel confirmed. Information about the hemodynamics of aneurysms was obtained. Two of these lesions were diagnosed as an aneurysmal porta-hepatic venous fistula, another 2 as a portal venous aneurysm, and the remaining 1 as a hepatic venous aneurysm.

Aneurysm

Persistence of archetypal JC virus DNA in normal renal tissue derived from tumor-bearing patients.

JC virus DNAs derived from the urine of nonimmunosuppressed individuals generally contain an archetypal regulatory region which may have generated various regulatory regions of JC virus from from the brain with progressive multifocal leukoencephalopathy (PML). In this study, we examined whether JC virus persisting in normal human kidney tissue contains the archetypal regulatory region. Renal medulla, cortex, and tumor from 32 patients bearing renal tumors were screened for JC virus DNA by blot hybridization. Viral DNA was detected in the medulla in 13 cases (41%), in the cortex in 2 cases (6%), but not at all from the tumor. A number of viral DNA-positive specimens (8 from the medulla and 2 from the cortex) were used to amplify and sequence viral regulatory regions by polymerase chain reaction. Structures of the regulatory regions from all the specimens were, with a few nucleotide variations, identical with that of the archetypal region which was previously detected in the JC virus DNA from urine. This finding supports the hypothesis that the JC virus associated with PML evolved from the archetypal JC virus during persistence in human hosts. Furthermore, we present evidence that renal JCV is replicating and that progeny virions are excreted into the urine.

Adult

Analysis of a human immunodeficiency virus type 1 isolate carrying a truncated transmembrane glycoprotein.

We have recently reported the isolation of a human immunodeficiency virus type 1 (HIV-1), KB-1gp32 carrying a shorter size (32 kDa) of transmembrane glycoprotein (TMP) from TALL-1 cells persistently infected with KB-1gp41 virus strain (Shimizu et al., 1990a). Endoglycosidase treatments showed that the different size of the TMP between the two strains was due to a truncation of 9 kDa of polypeptide in the KB-1gp32 TMP coding region. Sequence analysis revealed the substitution of a CAG codon to a TAG stop codon just downstream of the putative membrane-spanning domain of the TMP of KB-1gp32. This resulted in a truncation of some 133 amino acids of the cytoplasmic domain of TMP. The data indicate that a premature stop codon in KB-1gp32 has been introduced during adaption of the parental virus to TALL-1 cells. We have constructed two chimeric clones between the env region of a clone pKB-1, derived from KB-1gp32, and an infectious molecular clone pNL-432. We have also constructed a site-directed mutant of pNL-432 carrying a premature stop codon at the same position as the env stop codon of pKB-1. Among the three clones carrying a premature stop codon in env, only one chimeric clone was infectious to TALL-1 but not MT-2 cells. This clone contained the entire tat, rev, vpu, and env genes of pKB-1. The pNL-432 mutant was not infectious. The results suggest that some sequences of pKB-1 might compensate for the truncation of the TMP during replication in TALL-1 cells.

Amino Acid Sequence

Spinal cord cells innervating the bilateral parabrachial nuclei in the rat. A retrograde fluorescent double-labeling study.

The internal lateral nucleus (IL) of the parabrachial nucleus receives information from the spinal cord. The IL perhaps relays nociceptive signals to the intralaminar nuclei of the thalamus, apparently being implicated in the motivational-affective component of pain reactions. However, cells of origin of spinal fibers to the IL have not been investigated enough. We intended to clarify these cells, as well as their shapes, by retrograde double-labeling techniques. Fast blue and diamidino yellow dyes were injected, respectively, into the left and right ILs. The distribution of double-labeled cells was almost the same as that of single-labeled cells on both sides of the spinal cord. The total number of bilateral double-labeled cells was highest in the dorsolateral part of the lateral funiculus (DL), followed, in order, by lamina I, the dorsomedial part of the lateral funiculus (DM), lamina V and lamina VII. A few double-labeled cells were seen in laminae II-IV, VI, VIII and X. The ratio of the total number of bilateral double-labeled cells to the total number of bilateral single-labeled cells through the spinal cord was 43% in the DL, 37% in the DM, 28% in lamina V and 24% in lamina I. The ratio was 10% or less in the other remaining laminae. No marked differences were observed between the shapes of double- and single-labeled cells.

Amidines

Production of phytochelatins in Polygonum cuspidatum on exposure to copper but not to zinc.

We studied cellular resistance to copper of plant cells Polygonum cuspidatum. When callus of P. cuspidatum was incubated on medium containing 100 microM cupric sulfate, the callus grew as well as the control callus did. The copper content of the callus, however, was elevated to a similar level of the medium. When cell extracts of callus exposed to 100 microM cupric sulfate were fractionated by gel filtration chromatography, a specific copper peak was eluted at the region of molecular weights between 4000 and 1000. Since an appearance of the copper-containing materials was inhibited by buthionine sulfoximine and the partially purified copper-containing materials contained only three amino acids: glutamic acid, glycine and cystine, the materials were supposed to be gamma-glutamyl peptides phytochelatins. Callus of P. cuspidatum synthesized phytochelatins from 50 microM cupric sulfate and maximally at 100-150 microM cupric sulfate. When induction of phytochelatins by another heavy metal, zinc, was analyzed, the callus, however, did not synthesize phytochelatins on exposure to zinc sulfate up to 1 mM. These findings suggested that phytochelatins were required for resistance to copper but probably not to zinc in the plant cells.

Cells, Cultured

Stereotactic radiosurgery using a linear accelerator.

A basic and clinical study of radiosurgery using the linear accelerator (Linac) system for unremovable deep-seated brain tumors is reported. A Komai stereotactic ring was used to locate the target coordinates. The patient was laid on the Linac treatment table and held in the head fixation system. Irradiation was given in five positions. The dose profile by film dosimetry and Rando phantom was satisfactory. Seventeen tumors in 14 patients were treated. Clinical or histological diagnoses were nine metastases, one benign and two malignant gliomas, one meningioma, and one craniopharyngioma. Tumor sizes were between 8 and 30 mm. Doses were between 12 and 30 Gy. Computed tomographic evaluation after 3 months of 12 tumors in 11 survivors showed one complete remission, three partial remission, six no change, and two partial deterioration. For progressive tumors, Linac radiosurgery results are excellent.

Adult

A structurally abnormal erythropoietin receptor gene in a human erythroleukemia cell line.

Restriction endonuclease mapping demonstrates a 3' end deletion of one erythropoietin receptor (EpoR) gene in TF-1 cells, a human erythroleukemia cell line that overexpresses the EpoR and proliferates in response to erythropoietin (Epo). EpoR mRNA transcripts are highly abundant and normal in size. These findings raise interesting questions about the possible role of this EpoR gene abnormality in the pathogenesis of the erythroleukemia from which this cell line was derived. This is the first report of an abnormal human erythropoietin receptor gene.

Blotting, Northern

[A case of hepatocellular carcinoma responding to intraarterial infusion of epirubicin and mitomycin C].

A 64-year-old male was admitted for treatment of hepatocellular carcinoma. He was diagnosed as having many tumors in the area of S6 and the AFP level was elevated to 878 ng/ml. Initially, intraarterial infusion of Epirubicin only was not effective. After the first course of treatment, tumors increased in size and the AFP level was elevated. Next, intraarterial infusion of Epirubicin and Mitomycin C was performed. After the second course of treatment, the AFP level decreased from 5,006 ng/ml to 754 ng/ml and the tumors had almost completely disappeared on angiography. The tumors continued to decrease in size and thereafter the AFP level decreased to 10 ng/ml and was not elevated. The tumors almost completely disappeared in this case, and the coadministration of Epirubicin and Mitomycin C provided effective.

Antineoplastic Combined Chemotherapy Protocols

Effect of cacao husk extract on human immunodeficiency virus infection.

A sodium hydroxide extract from cacao husk inhibited the cytopathic effect of human immunodeficiency virus type 1 (HIV-1) against HTLV-1-transformed T-cell lines MT-2 and MT-4. It also inhibited syncytium formation between HIV-infected and uninfected lymphoblastoid T-cell line, MOLT-4. The anti-HIV activity was concentrated by membrane filter fractionation to a fraction with molecular weight of 100-300 KDa. Anti-HIV activity of the extract was attributable to interference with the virus adsorption, rather than to inhibition of the virus replication after adsorption.

Cacao

Postsynaptic potentials recorded from medullary neurones following stimulation of carotid sinus nerve.

Projections of the carotid sinus nerve (CSN) onto medullary neurones were studied with intracellular recording. Three types of postsynaptic potentials (EPSP, EP-IPSP and IPSP) were recorded by stimulation of the ipsilateral CSN. Of the total of 121 neurones, positions of 54 were identified by intracellular dye. The other 67 were positioned by extrapolation. They were distributed over 5 medullary nuclei: (1) nucleus of the solitary tract (NTS); (2) paramedian reticular nucleus (NPR); (3) perihypoglossal nucleus (PXII); (4) lateral tegmental field (FTL); and (5) nucleus ambiguus. Since penetration of microelectrodes and injection of dye into the NTS neurones was difficult, neurones of the other 4 nuclei were examined. The IPSPs were dominant in small NPR neurones, while the EPSPs were dominant in large neurones of the other 3 nuclei. Both the NA and PXII neurones showed forms of a motor type neurone, while the FTL neurones showed various forms. The EPSPs with onset latency as short as 2-4 msec were frequently recorded in different nuclei. This strongly suggests that the CSN projects monosynaptically onto different nuclei in the medulla.

Animals

[Electronmicroscopic observation on acinic cell tumors of the parotid gland].

Under the electronmicroscope we observed a case of an acinic cell tumor of the left parotid gland. The patient was a 63-year-old woman who has suffered three times from local recurrences. The cytoplasma of the tumor cells showed the well-organized mitochondria, rouch endoplasmic reticula, Golgi's complexes and other organellas. Especially the cytoplasmas of the tumor cells, which formed acinus-like lumens, contained various-shaped secretory granules in great numbers. In addition, pycnotic-nucleated oncocytes with secretory granules could be observed.

Female

Automated determination of red cell methaemoglobin reductase activity by a continuous-flow system for screening hereditary methaemoglobinaemia.

A flow diagram for the automated determination of ferricyanide reductase activity in red blood cells was prepared in the modules from AutoAnalyzer AA I (Technicon Instruments Inc). Ferricyanide reductase assay can be substituted for assay of cytochrome b5 reductase (EC 1.6.2.2), which plays a major role in reducing methaemoglobin in erythrocytes, and is defective specifically in the erythrocytes of patients with hereditary methaemoglobinaemia. The effective sampling rate of the analysis is 30/h, and less than 0.05 ml of whole blood is required. Interference of haemoglobin with absorption by potassium ferricyanide at 420 nm is effectively exculded by dialysis. This automated method was compared with the accepted diaphorase method, and it distinguished clearly the ferricyanide reductase activity of cord bloods from that of adult bloods. The activity of the blood from a patient with hereditary methaemoglobinaemia was only residual. It is suggested that the method is useful as a mass screening test for hereditary methaemoglobinaemia.

Adult