Biomedical subjects

T Kimura

Publications and source records attributed to T Kimura.

At least 19 recordsLinked to original sources

PubMed2001

Regulation of thyroid cell proliferation by TSH and other factors: a critical evaluation of in vitro models.

TSH via cAMP, and various growth factors, in cooperation with insulin or IGF-I stimulate cell cycle progression and proliferation in various thyrocyte culture systems, including rat thyroid cell lines (FRTL-5, WRT, PC Cl3) and primary cultures of rat, dog, sheep and human thyroid. The available data on cell signaling cascades, cell cycle kinetics, and cell cycle-regulatory proteins are thoroughly and critically reviewed in these experimental systems. In most FRTL-5 cells, TSH (cAMP) merely acts as a priming/competence factor amplifying PI3K and MAPK pathway activation and DNA synthesis elicited by insulin/IGF-I. In WRT cells, TSH and insulin/IGF-I can independently activate Ras and PI3K pathways and DNA synthesis. In dog thyroid primary cultures, TSH (cAMP) does not activate Ras and PI3K, and cAMP must be continuously elevated by TSH to directly control the progression through G(1) phase. This effect is exerted, at least in part, via the cAMP-dependent activation of the required cyclin D3, itself synthesized in response to insulin/IGF-I. This and other discrepancies show that the mechanistic logics of cell cycle stimulation by cAMP profoundly diverge in these different in vitro models of the same cell. Therefore, although these different thyrocyte systems constitute interesting models of the wide diversity of possible mechanisms of cAMP-dependent proliferation in various cell types, extrapolation of in vitro mechanistic data to TSH-dependent goitrogenesis in man can only be accepted in the cases where independent validation is provided.

Animals↗

PubMed1995

Midkine is a heat and acid stable polypeptide capable of enhancing plasminogen activator activity and neurite outgrowth extension.

We studied about the physicochemical stability of a novel heparin-binding growth/differentiation factor, midkine (MK). It was found that synthetic human MK was heat and acid stable. Neither incubation at 80 degrees C for 90 sec nor treatment at low pH affected the elution profile of MK molecule on the high performance liquid chromatography. This physicochemical stability was maintained in the biological activities of MK to enhance plasminogen activator (PA) activity in bovine endothelial cells as well as to promote neurite outgrowth of rat brain cells. A similar stability was observed both with recombinant murine MK and with its homologous protein, recombinant human pleiotrophin. Comparison of physicochemical stability with other several growth factors suggested that MK/pleiotrophin was a unique family of heat and acid stable polypeptides capable of enhancing PA activity and neurite outgrowth.

Animals↗

PubMed1995

D1 cap region involved in the receptor recognition and neural cell survival activity of human ciliary neurotrophic factor.

Human ciliary neurotrophic factor (hCNTF), which promotes the cell survival and differentiation of motor and other neurons, is a protein belonging structurally to the alpha-helical cytokine family. hCNTF was subjected to three-dimensional structure modeling and site-directed mutagenesis to analyze its structure-function relationship. The replacement of Lys-155 with any other amino acid residue resulted in abolishment of neural cell survival activity, and some of the Glu-153 mutant proteins had 5- to 10-fold higher biological activity. The D1 cap region (around the boundary between the CD loop and helix D) of hCNTF, including both Glu-153 and Lys-155, was shown to play a key role in the biological activity of hCNTF as one of the putative receptor-recognition sites. In this article, the D1 cap region of the 4-helix-bundle proteins is proposed to be important in receptor recognition and biological activity common to alpha-helical cytokine proteins reactive with gp130, a component protein of the receptors.

Amino Acids↗

PubMed1995

Mutation frequency of the p16/CDKN2 gene in primary cancers in the upper digestive tract.

We report a highly frequent homozygous deletion of the p16/CDKN2 gene in the esophageal cancer cell line and a relatively high frequency of homozygous deletion in gastric cancer cell lines. In contrast, in primary esophageal carcinomas, mutation frequency of the p16/CDKN2 gene has been controversial (0, 21, and 52% previously reported), and no reports are available for the mutation frequency of this gene in surgical specimens of gastric carcinomas. Here we report that four (16%) of 25 primary esophageal squamous cell carcinomas were found to be mutated, one in exon 1 and three in exon 2, and that no mutations were observed in 19 surgical specimens of gastric adenocarcinomas. This is the first report showing the absence or quite low frequency of mutation in surgical specimens of gastric carcinomas.

Base Sequence↗

PubMed1995

Calcium-dependent conformation of a mouse macrophage calcium-type lectin. Carbohydrate binding activity is stabilized by an antibody specific for a calcium-dependent epitope.

We established monoclonal antibodies (mAbs) against the mouse macrophage galactose/N-acetylgalactosamine-specific lectin (MMGL) that is a 42-kDa calcium-dependent lectin, using a solid phase carbohydrate binding assay as a novel strategy for screening mAbs. The specificity of six mAbs were investigated by antibody binding to native or recombinant forms (rML) of MMGL, flow cytometry, and immunoprecipitation using a macrophage cell line RAW264.7. Four of these mAbs strongly inhibited the binding of fluorescein 5-isothiocyanate-labeled galactosylated polylysine to immobilized rML, one inhibited moderately, and one did not inhibit binding. The competitive binding study revealed that the binding sites of these four blocking mAbs were closely related to each other but were different from the rest of these mAbs. A non-blocking mAb having a unique binding specificity (LOM-11) exhibited calcium-dependent binding to rML, suggesting that calcium-dependent epitope was not situated in the vicinity of the ligand binding site. Furthermore, pretreatment of rML with the mAb LOM-11 preserved ligand binding activity, especially in a low calcium environment. The four blocking mAbs mentioned above facilitated the binding of the mAb LOM-11 to rML. These results indicate that there is a positive cooperativity between the lectin's ligand binding site and its physically distinct calcium-dependent epitope.

Animals↗

PubMed1995

Spatial distribution of omega-agatoxin IVA binding sites in mouse brain slices.

A peptide toxin derived from funnel-web spider venom, omega-agatoxin IVA, blocks voltage-sensitive calcium channels. Many pharmacological and electrophysiological studies have shown that these channels are widely distributed in both the central nervous system (CNS) and neuromuscular junctions. However, a direct morphological demonstration of the binding sites of this toxin is still lacking. To identify which cells have the binding sites, a biologically active, biotin-conjugated omega-agatoxin IVA was applied to mouse cerebellar and hippocampal slices. Confocal microscopy revealed that omega-agatoxin IVA binding sites were distributed on the somata of Purkinje cells, cerebellar granule cells and interneurons, as well as on the dendrites of Purkinje cells. In the hippocampus, the binding sites were localized on the somata of pyramidal cells of the CA1-CA4 region and on the somata of granule cells in the dentate gyrus. A sequential competitive reaction confirmed the specificity of the binding in the cerebellum and CA1 pyramidal cells, and also suggested a difference in the binding affinity between CA1 and CA3 pyramidal cells. Since a high concentration of omega-agatoxin IVA (2 microM) was needed for the present study, the omega-agatoxin IVA binding sites presented in this study may represent "P-type" and "Q-type" calcium channels.

Animals↗

PubMed1995

High-performance liquid chromatographic determination of diadenosine 5',5'"-p1,p4-tetraphosphate with precolumn fluorescence derivatization and its application to metabolism study in whole blood.

Diadenosine 5',5'"-p1,p4-tetraphosphate (Ap4A) was converted with chloroacetaldehyde to the fluorescent di-1,N6-ethenoadenosine derivative within 60 min at 80 degrees C. It was separated by reversed-phase HPLC and detected fluorimetrically (excitation and emission wavelengths of 275 and 410 nm, respectively). The detection limit of Ap4A was ca. 0.2 microgram/ml in plasma when 10 microliters of the sample was applied to the column. The rate of degradation of Ap4A added to whole blood (5 micrograms/ml) was examined using this method. Half-lives (means +/- S.E., n = 3) were 0.88 +/- 0.30 min (in rat blood), 13.7 +/- 3.6 min (in dog blood) and 17.2 +/- 1.4 min (in human blood). A marked species difference in the degradation rate of Ap4A in blood was observed.

Adenosine↗

PubMed1995

Are advanced glycation end-products associated with amyloidosis in Alzheimer's disease?

Recent studies have suggested that advanced glycation end-products (AGE) of the Maillard reaction are associated with amyloidosis in Alzheimer's disease. To evaluate this possibility, the present immunohistochemical study was undertaken to locate AGE in cerebral cortices of Alzheimer's disease, using a monoclonal antibody specific for AGE-proteins. Deposits of beta-amyloid protein within cores of classic senile plaques and vascular walls in amyloid angiopathy showed no AGE-positive reaction, while primitive plaques, coronas of classic plaques and some glial cells were positive for AGE. These findings are inconsistent with the suggestion that AGE may be involved primarily in amyloidosis in Alzheimer's disease.

Aged↗

PubMed1995

Substrate-induced acceleration of N-ethylmaleimide reaction with the Cys-65 mutant of the transposon Tn10-encoded metal-tetracycline/H+ antiporter depends on the interaction of Asp-66 with the substrate.

We previously reported that the reaction of [14C]N-ethylmaleimide (NEM) with the S65C mutant of the transposon Tn10-encoded metal-tetracycline/H+ antiporter (TetA(B)) is competitively inhibited by tetracycline [Yamaguchi, A. et al., FEBS Lett. 322 (1993) 201-204]. However, this observation has been revealed to be a mistake. The reaction of [14C]NEM with S65C TetA(B) was significantly and reproducibly accelerated by tetracycline, i.e. not inhibited. When Asp-66 was replaced by Ala, the reaction of NEM with the Cys-65 residue was no longer affected by tetracycline. In contrast, when Arg-70 was replaced by Ala, the acceleration of the reaction was unaltered. The tetracycline acceleration of the reaction to the Cys-65 residue was further stimulated with energization of the membrane on the addition of NADH. On the other hand, the tetracycline-induced acceleration was not observed in the absence of a divalent cation. These observations indicated that the Cys-65 locus is exposed to the medium according to the interaction of a divalent cation-tetracycline chelation complex with Asp-66.

Amino Acid Sequence↗

PubMed1995

Carcinoma of the reconstructed stomach tube following esophageal resection for a benign stricture: report of a case and review of the literature.

We report herein the case of a 60-year-old woman who presented with dysphagia and anorexia and was subsequently diagnosed as having gastric cancer of the reconstructed stomach tube 36 years after undergoing surgery for a benign esophageal stricture. Reports on carcinoma of the reconstructed stomach tube are rarely found and interestingly, all of the previous cases, which were documented only in the Japanese literature, corresponded to metachronous double cancers after esophageal malignancies. To our knowledge, this is the first case of carcinoma of the reconstructed stomach tube following esophageal resection for a benign stricture, and it is thought that the carcinoma probably developed at the site of the anastomosis a long time after the first operation. We reviewed 30 cases of carcinoma of the reconstructed stomach tube for which the clinicopathological data was complete, and we believe that this new type of cancer needs more than 10 years to develop and should be defined as "carcinoma of the gastric remnant".

Adenocarcinoma↗

PubMed1995

The successful repair of annuloaortic ectasia using Cabrol's operation in a 5-year-old child with Marfan's syndrome of the forme fruste type.

This report describes our experience of treating a 5-year-old boy with annuloaortic ectasia and a presumptive diagnosis of Marfan's syndrome. He had elongation of the distal aortic arch and dilatation of the abdominal aorta. Surgical repair of annuloaortic ectasia was successfully carried out using Cabrol's operation, following which no significant perioperative complications developed. To our knowledge, this is the first reported case of Cabrol's operation being successfully performed on a child aged 5 years or less.

Aortic Diseases↗

PubMed1995

Biochemical and immunohistochemical analysis of cathepsins B, H, L and D in human melanocytic tumours.

We carried out biochemical and immunohistochemical analyses of cathepsins B, H, L and D in human melanocytic tumours using monospecific antibodies against rat cathepsins. In Western blot analysis, anti-rat cathepsin antibodies reacted with the cathepsins from normal human tissues and human malignant melanoma. However, the molecular profiles of the cathepsins from human melanoma were slightly different from those of the rat cathepsins, suggesting a distinct intracellular processing mechanism for cathepsins in human melanoma. Although cathepsins B, H, L and D were expressed in primary and metastatic melanomas and pigmented naevi immunohistochemically, the intensity of staining in metastatic melanomas was stronger than in primary melanomas and pigmented naevi. These findings suggest that anti-rat cathepsin antibodies may be useful in biochemical and/or immunohistochemical analysis of human melanocytic tumours.

Animals↗

PubMed1995

Nucleotide sequence analysis of two nuclear inclusion body and coat protein genes of a sweet potato feathery mottle virus severe strain (SPFMV-S) genomic RNA.

Recombinant DNA molecules containing cDNA of a sweet potato feathery mottle virus severe strain (SPFMV-S) RNA genome were constructed and the partial nucleotide sequences were determined for three DNA inserts, which cover 4-2 kb from the 3'-terminus excluding the poly (A) tail. This region of the genome consists of an open reading frame of 1340 amino acids (a.a.) and a 3'-non-translated region of 224 nucleotides. The protein products expected were 6K2 (53 a.a.), NIa (435 a.a.), NIb (521 a.a.) and CP (315 a.a.). Among NIa, NIb and coat proteins, the NIb protein was found to be the most conserved (59-68%) when compared to the corresponding proteins of other distinct potyviruses.

Amino Acid Sequence↗

PubMed1995

New chronic pancreatitis model with diabetes induced by cerulein plus stress in rats.

To establish a new experimental model of chronic pancreatitis (CP) with diabetes, we investigated pancreatic endocrine function, blood flow, and histopathology in CP induced by repetition of cerulein injection plus water immersion stress in rats. CP rats were treated with water immersion stress for 5 hr and two intraperitoneal injections of 20 micrograms/kg body weight of cerulein once a week for 16 weeks. In the CP group, pancreatic contents of protein, amylase, elastase, and lipase significantly decreased to 64, 38, 23, and 68% of the control group, respectively. In oral glucose tolerance test (glucose 2 g/kg body wt), blood glucose level in the CP group was 212.1 +/- 97.8 mg/dl (mean +/- SD) at 30 min and was significantly higher than the control group (126.3 +/- 15.4 mg/dl)(P < 0.05). Two of seven rats in the CP group showed an obvious diabetic insulin in the CP group was 640.1 +/- 148.7 pM, significantly lower than in the control group (1133.4 +/- 242.0 pM)(P < 0.001). However, insulin content in the pancreas was 12.37 nmol/pancreas). In CP rats, winding and dilatation of surface blood vessels and gland atrophy were evident. Marked fibrosis, fatty changes, and destruction of lobular architecture were also demonstrated microscopically, although the structure of each pancreatic islet was preserved and each islet was fully stained with anti-insulin antibody. In the CP group, pancreatic blood flow by the hydrogen gas-clearance method was 197.6 +/- 33.0 ml/min/100 g, which was significantly less than the control group (276.2 +/- 19.1 ml/min/100 g) (P < 0.001). Thus, we conclude that the CP model induced by cerulein plus stress is a new CP model with diabetes in rats, in which the glucose tolerance was impaired without loss of insulin reserve.

Amylases↗

PubMed1995

High susceptibility of U937-derived subclones to infection with human immunodeficiency virus type 1 is correlated with virus-induced cell differentiation and superoxide generation.

The promonocytic human leukemic cell line U937, when infected with lymphotropic human immunodeficiency virus type 1 (HIV-1), becomes a continuous virus producer. A total of 46 U937-derived subclones in suspension was isolated and classified into three (2 high, 42 middle, and 2 low) types based on their susceptibility to the infection. By analyzing subclones before infection, we found that the high-type subclones expressed LFA-1 antigens at a relatively low level. In addition, the ability of these subclones to induce adherence after exposure to phorbol 12-myristate 13-acetate (PMA) was reduced. In contrast, a transition by HIV-1 infection to adherent macrophage-like cells was induced only in the high-type, but not in the low-type subclones. The high-type adherent cells obtained by HIV-1 infection were followed by further lineage to become retrodifferentiated suspension cells showing reduced syncytia formation ability. Superoxide was generated in the high-type subclones, without PMA-mediated differentiation, from the early stage of infection before HIV-1 replication, as well as during undifferentiated, differentiated and retrodifferentiated stages. In contrast, it was only transiently generated at acute phase of HIV-1 replication in low-type subclones. Long-term culture of the low-type subclones decreased the expression of major structural viral protein Gag and also virus production. Thus, the mechanism by which PMA differentiates U937 cells is not the same as that induced by HIV-1 infection. The latter mechanism results in high susceptibility to infection. The HIV-1 phenotypes of finally obtained persistently infected cells were also affected by the cell stages at the time of infection.

Cell Cycle↗

PubMed1995

Viral activation from latency during retrodifferentiation of U937 cells exposed to phorbol ester followed by infection with human immunodeficiency virus type 1.

To determine the mechanism underlying the human immunodeficiency virus type 1 (HIV-1) latency and its activation in monocyte/macrophage lineage, the human promonocytic cell line U937 was infected with HIV-1 after differentiation with varied doses of phorbol 12-myristate 13-acetate (PMA). Variously differentiated intermediate stages were generated in U937 cells in a dose-dependent manner. When these cells were infected with lymphotropic HIV-1, the kinetics of the production of HIV-1 DNA, the appearance of HIV-1 antigen-positive cells, and viral production in the conditioned media were slower at higher doses of PMA. This different susceptibility to the infection was not due to the rate of HIV-1 adsorption. Viral replication from latency in the differentiated cells was activated in proportion with the retrodifferentiation observed in long-term cultures of the host cells. Thus, our data demonstrate the close correlation between the regulation of HIV-1 replication and the differentiation stage of monocyte/macrophage lineage cells at the time of HIV-1 infection. The retrodifferentiation phenomenon in infected cells seems to be particularly important for understanding the mechanisms for HIV-1 activation from latency.

Base Sequence↗

PubMed1995

Repair of complete syndactyly by tissue expansion and composite grafts.

Repair of complete syndactyly by a combination of tissue expansion and composite grafts from the glabrous non-weight bearing areas of the foot has been performed on three syndactylies in two patients. The commissure and the lateral areas of the proximal and middle phalanges were covered with expanded skin and the separated fingertips were covered with composite grafts. Without using an ordinary skin graft, this method can provide aesthetically excellent results with good skin colour and texture.

Female↗

PubMed1995

Relationship between functional levels and movement in tetraplegic patients. A retrospective study.

The aim of the present study was to set targets for each spinal lesion level after determining the relationship between the spinal lesion level and movement abilities in patients with tetraplegia following injury to the cervical cord. A total of 109 patients, 96 men and 13 women were included in the study. We mainly examined locomotion and transfer capabilities according to Zancolli's classification. The results of this study showed that 50% of the patients classified as C6A, 75% of C6B1 and 96% of the patients classified C6B2 accomplished bed transfer. The number of patients who could manage toilet transfer was 53% in the group classified as C6B1 and 85% in group C6B2. These results suggest that achievement of those classified as C6B2 is a clue to the assumption that the patient will achieve toilet transfer capability and can perform ADL independently.

Activities of Daily Living↗