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T Kondo

Publications and source records attributed to T Kondo.

At least 433 records · Page 24Linked to original sources
PubMed1998

Haemorrhages in the posterior cricoarytenoid muscles--an unspecific autopsy finding.

Atraumatic haemorrhages in the posterior cricoarytenoid (PCA) muscles can be observed for from 1% to 9% of various causes of death. It has been claimed that there is an association between these findings and the cause of death, particularly coronary death. Additionally it has been assumed that haemorrhages in the PCA muscles may be caused by an asphyxial mechanism and it has even been suggested that the haemorrhages may be a "sign" which could be used to differentiate between natural and unnatural death. Because of the differing views we carried out additional research into the course of these haemorrhages. Six characteristic cases out of 2060 autopsies with macroscopically diagnosed haemorrhages in the PCA muscles are presented. The six cases included acute heart failure, death caused by bolus, drowning, trauma of brain and skull, exsanguination from polytrauma and choking after aspiration of vomit. These cases were completely different with regard to all the circumstances of death. On the basis of these findings and in contrast to the literature it cannot be shown that proofs exist for a correlation between the haemorrhages and the causes and the manner of death. As a consequence it must be stated that haemorrhages in the PCA muscles do not have any diagnostic significance.

Adult↗
PubMed1998

Resonating circadian clocks enhance fitness in cyanobacteria.

In some organisms longevity, growth, and developmental rate are improved when they are maintained on a light/dark cycle, the period of which "resonates" optimally with the period of the endogenous circadian clock. However, to our knowledge no studies have demonstrated that reproductive fitness per se is improved by resonance between the endogenous clock and the environmental cycle. We tested the adaptive significance of circadian programming by measuring the relative fitness under competition between various strains of cyanobacteria expressing different circadian periods. Strains that had a circadian period similar to that of the light/dark cycle were favored under competition in a manner that indicates the action of soft selection.

Circadian Rhythm↗
PubMed1998

Characteristics of intracellular transferrin produced by human fibroblasts: its posttranscriptional regulation and association with tubulin.

Transferrin (Tf), an iron-binding protein, was investigated in the cultured human fibroblast which is a major cell type in connective tissues. Tf is a major iron-transporting protein and has an important role in iron metabolism. Using two-dimensional gel electrophoresis, we demonstrated the eight subtypes of Tf produced by cultured normal human fibroblasts and their down-regulation after the immortalization of human cells, an essential early step of in vitro transformation. However, the amount of Tf mRNA in the immortalized cells was equal to that in the normal human fibroblasts, suggesting that the down-regulation occurred at the posttranscriptional level. The amount of Tf receptor increased in the immortalized cells in spite of a decrease in the amount of intracellular Tf. Interestingly the produced Tf associated with microtubules. These findings suggest a novel aspect of Tf characteristics in human fibroblasts.

Cell Line↗
PubMed1998

Hammerhead ribozymes against gamma-glutamylcysteine synthetase mRNA down-regulate intracellular glutathione concentration of mouse islet cells.

gamma-Glutamylcysteine synthetase (gamma-GCS) is a key enzyme in glutathione synthesis and is thought to play a significant role in intracellular detoxification systems. To specifically suppress gamma-GCS gene expression, we constructed two different hammerhead ribozymes against gamma-GCS mRNA transcripts. Two cleavage sites were targeted as follows: site 1 for anti-gamma-GCS ribozyme (H), a GUU triplet located from +348 to +350 of the gamma-GCS heavy chain, and site 2 for anti-gamma-GCS ribozyme (L), a GUU triplet located from +235 to +237 of the gamma-GCS light chain. The anti-gamma-GCS ribozymes effectively cleaved gamma-GCS mRNA in a cell-free system. When transfected into a Min-6 mouse islet cell line, these anti-gamma-GCS ribozymes not only suppressed gamma-GCS gene expression, but also reduced intracellular glutathione concentration. These results suggest that the ribozyme-mediated down-regulation of gamma-GCS gene expression may be useful for analyzing the glutathione-associated cellular defense systems of pancreatic islet cells.

Animals↗
PubMed1998

Contribution of brainstem hypoperfusion to the tracheal and phrenic nerve responses to high-pressure lung inflation in the dog.

Lung inflation to high airway pressure is known to produce tracheal constriction following an initial dilation. This is attributed to stimulation of various pulmonary receptors. In an attempt to find cause of this response, we investigated in 20 decerebrated, tracheostomized and paralyzed dogs changes in the tracheal smooth muscle tension, arterial pressure and the phrenic nerve activity to high-pressure lung inflation. A high-pressure lung inflation evoked a contraction of tracheal smooth muscle following its short-lasting relaxation, and a persistent hypotension. After hilar denervation which eliminated all pulmonary afferents, a high-pressure lung inflation still evoked contraction of tracheal smooth muscle (an increase of 3.7 times) and augmented amplitude and frequency of phrenic bursts. Bilateral transections of sympathetic fibers to the lung, or blockade of arterial perfusion to the carotid sinus and denervation of the carotid sinus bilaterally did not alter the tracheal muscle and phrenic responses to a high-pressure lung inflation. We further found that severe hypotension alone caused similar responses of the tracheal smooth muscle contraction and augmented phrenic activity. Finally, when blood supply to the brainstem was transiently obstructed by clamping both the vertebral and internal carotid arteries bilaterally, the same responses were observed. In contrast, when blood hypoperfusion to the brainstem was prevented by means of extracorporeal circulation, a high-pressure lung inflation failed to evoke such contraction of tracheal smooth muscle and or increased phrenic activity. After transection of the vagus nerves bilaterally at the cervical level the tracheal muscle response to lung inflation was abolished but that of phrenic nerve was preserved. We concluded that the tracheal smooth muscle contraction and phrenic responses induced by high-pressure lung inflation may be in part attributed to brainstem hypoperfusion.

Animals↗
PubMed1998

Genetic control of murine limb morphogenesis: relationships with human syndromes and evolutionary relevance.

Over the past ten years, the discovery and functional characterisation of murine Hox genes has led to a better understanding of some of the molecular mechanisms underlying limb development. It has also shed some light on the potential genetic events which have accompanied the fin-to-limb transition, an evolutionary step of critical importance which opened the way to the evolution of higher vertebrates. This convergence between developmental biology and the sciences of evolution is one of the synergistic interface that has been established recently thanks to the use of genetic engineering and transgenic animals. The increasing number of human genetic syndromes which are derived from mutations in developmental control genes remind us that many human genetic diseases are nothing else but alterations in our developmental programme. Here, we illustrate these various issues by discussing the function of Hox genes during limb development.

Animals↗
PubMed1998

Glutathione homeostasis in human hepatic cells: overexpression of gamma-glutamylcysteine synthetase gene in cell lines resistant to buthionine sulfoximine, an inhibitor of glutathione synthesis.

The synthesis of glutathione (GSH) and its conjugation to xenobiotics are essential for detoxification in liver cells. To understand how cellular levels of GSH are balanced in response to environmental stress, we cloned two cell lines, HLE/BSO1-1 and HLE/BSO1-2, from human hepatic HLE/WT cells resistant to buthionine sulfoximine (BSO), an irreversible inhibitor of gamma-glutamylcysteine synthetase (GCS). HLE/BSO1-1 and HLE/BSO1-2 showed 35- and 40-fold higher resistance respectively, than the wild type to BSO. In the absence of BSO, cellular levels of GSH were 3.0-fold higher, whereas levels of Pi class glutathione thiol transferase, GSTP1, were 2-fold lower, in the subclones than in the wild type cells. GCS heavy subunit (GCSh) mRNA level were 2.5-fold higher in HLE/BSO1-1 and HLE/BSO1-2 as compared with HLE/WT. Sequences between -315 and -241 base pairs of the 5' region, which contain an AP1 site, were shown to be responsible for the enhanced expression of GCSh in HLE/BSO1-1 cells. The expression of a dominant-negative mutant of c-Jun was found to inhibit the AP1-dependent GCSh promoter activity in HLE/WT and HLE/BSO1-1. Both protein level of c-Jun and binding activity of AP-1 were increased in both HLE/BSO1-1 and HLE/BSO1-2 cells. The up-regulation of GCSh gene appeared to be due to enhanced GCSh promoter acting through AP-1 activation in BSO-resistant hepatic cells.

Binding Sites↗
PubMed1998

Talipexole protects dopaminergic neurons from methamphetamine toxicity in C57BL/6N mouse.

The effect of protection of dopaminergic neurons by talipexole, a dopamine (DA) agonist, is investigated on a methamphetamine (MA)-induced parkinsonism model of mice (C57BL/6N). The reduction of tyrosine hydroxylase activity in the striatum 72 h after MA (5 mg/kg every 2 h, four times) treatment was attenuated by the administration of talipexole (0.25 mg/kg or 1.0 mg/kg) prior to the administration of MA. In an in vitro experiment, talipexole inhibited the adduction reaction of hydroxyl radicals to salicylate. Taken together, these data suggest that the protective effect of talipexole on DA neurons is, in part, caused by the hydroxyl radical-scavenging action of the drug.

Animals↗
PubMed1998

An active efflux system for heavy metals in cisplatin-resistant human KB carcinoma cells.

The mechanism for cisplatin resistance in cisplatin-resistant KCP-4 cells was studied. Although multidrug resistance-associated protein (MRP) was not detected in KCP-4 cells, the cells were more resistant to heavy metals than multidrug-resistant C-A120 cells that overexpressed MRP. KCP-4 cells expressed metallothionein, but it was scarcely involved in cisplatin resistance in these cells. KCP-4 cells did not express canalicular multispecific organic anion transporter (cMOAT). The glutathione (GSH) level was 4.7-fold higher in KCP-4 cells than in KB-3-1 cells. When the GSH level in KCP-4 cells was decreased by treating the cells with buthionine sulfoximine and nitrofurantoin, the accumulation of and sensitivity to cisplatin in the cells were increased. C-A120 cells were only 3.0-fold more resistant to cisplatin than KB-3-1 cells and this resistance was not affected by the increased glutathione level. The accumulation of platinum in C-A120 and KCP-4 cells was 68.5 and 20.4% of that in KB-3-1 cells, respectively, while the intracellular levels of antimony potassium tartrate in C-A120 and KCP-4 cells were 13.2 and 9.9% of that in KB-3-1 cells, respectively. The ATP-dependent efflux of antimony was enhanced in both C-A120 and KCP-4 cells. These results, taken together, suggest an efflux pump for heavy metals different from MRP and cMOAT is involved in cisplatin resistance in KCP-4 cells.

ATP-Binding Cassette Transporters↗
PubMed1998

Report of the Second Equine Leucocyte Antigen Workshop, Squaw valley, California, July 1995.

The final assignment of antibody clusters for leucocyte antigens and immunoglobulins, as described in detail in Sections 3 and 4, is summarized in Table 4. Together with other mAbs developed outside of ELAW II (Table 9) this pool of reagents represent a powerful array of tools for the study of equine immunity. The Second Equine Leucocyte Antigen Workshop made considerable advances in pursuing the objectives of establishing the specificities of mAbs and achieving consensus on the nomenclature for equine leucocyte and immunoglobulin molecules. Of equal importance, several productive collaborations were fostered among the participating laboratories and observers. Overall, enormous advances have been made in the past decade since mAbs specific for equine leucocyte antigens and immunoglobulins were first reported. There remains enormous scope and need for further studies of equine leucocyte antigens and immunoglobulins, both for the purposes of comparative immunology and for the good of the horse. In the future novel techniques will be required to develop reagents for specific target antigens such as the orthologues of the CD25 or CD45 isoforms. In studies of equine immunoglobulins the functional role of the IgG isotypes must be better established, reagents for IgE must be developed, and cloning of the immunoglobulin heavy chain genes will be essential if the complexities of the IgG sub-isotypes are to be elucidated. The tasks still facing the currently small group of equine immunologists throughout the world remain formidable, and will only be tackled successfully in a spirit of collaboration.

Animals↗
PubMed1998

Production of monoclonal antibodies to six isotypes of horse immunoglobulin.

Stable clones of 18 mouse hybridomas that produce monoclonal antibodies (MAbs) to six isotypes of horse immunoglobulin were produced. The number of hybridomas of different specificities are: four to IgGa, four to IgGb, one to IgGc, four to IgG(T), two to IgM, and three to IgA. The immunoglobulin isotypes purified from affinity columns bound with each MAb showed variable mobility in agarose-gel electrophoresis. Migration proceeded from the anode as: IgG(T), IgA, IgM, IgGc, IgGb and IgGa. The purified isotypes also demonstrated a single precipitin line when in immunoelectrophoresis against isotype-specific or polyclonal antisera, raised against the purified isotype or whole equine serum, respectively.

Animals↗
PubMed1998

Mechanism of UV-induced apoptosis in human leukemia cells: roles of Ca2+/Mg(2+)-dependent endonuclease, caspase-3, and stress-activated protein kinases.

Ultraviolet light (UV) induced rapid apoptosis of U937 leukemia cells, concurrent with DNA fragmentation and cleavage of poly(ADP-ribose)polymerase (PARP) by activated caspase-3. The in vitro reconstitution of intact HeLa S3 nuclei and apoptotic U937 cytosolic extract (CE) revealed that (i) Ca2+/Mg(2+)-dependent, Zn(2+)-sensitive endonuclease activated in the apoptotic CE induced DNA ladder in HeLa nuclei at pH 6.8-7.4, (ii) activated caspase-3 cleaved PARP in HeLa nuclei, and (iii) when the apoptotic CE was treated with the caspase-3 inhibitor (1 microM Ac-DEVD-CHO) or the caspase-1 inhibitor (10 microM Ac-YVAD-CHO), the former, but not the latter, caused a 50% inhibition of DNA fragmentation and the complete inhibition of PARP cleavage in HeLa nuclei. Similarly, Ac-DEVD-CHO (100 microM) inhibited apoptosis and DNA ladder by 50% and PARP cleavage completely in UV-irradiated U937 cells, but Ac-YVAD-CHO (100 microM) did not. Thus, UV-induced apoptosis of U937 cells involves the Ca2+/Mg(2+)-dependent endonuclease pathway and the caspase-3-PARP cleavage-Ca2+/Mg(2+)-dependent endonuclease pathway. The former pathway produced directly 50% of apoptotic DNA ladder, and the latter involved activated caspase-3 and PARP cleavage, followed by formation of the remaining 50% DNA ladder by the activated endonuclease. In UV-irradiated B-cell lines, further, p53-dependent increase of Bax resulted in a greater caspase-3 activation compared to its absence. However, UV-induced activation of JNK1 and p38 was not affected by the caspase-1 and -3 inhibitors in U937 cells, so that caspases-1 and -3 do not function upstream of JNK1 and p38.

Apoptosis↗
PubMed1998

An equine herpesvirus type 1 recombinant with a deletion in the gE and gI genes is avirulent in young horses.

The cell culture-adapted KyA strain of equine herpesvirus type 1 (EHV-1) has been found to be attenuated in young horses (Matsumura et al., 1996, Vet. Microbiol. 48, 353-365). The KyA strain lacks at least six genes in its genome, including those encoding glycoproteins gE and gI. To elucidate whether EHV-1 glycoproteins gE and gI play a role in viral virulence, we have constructed an EHV-1 recombinant that has the genes encoding both gE and gI deleted from its genome and its revertant. Growth properties of the deletion mutant virus in vitro were compared with those of the parent and the revertant viruses. Plaque size of the mutant virus in fetal horse kidney (FHK) cells was significantly smaller than those of the parent and the revertant viruses. In one-step growth experiments, however, the yields of infectious virus from FHK cells infected with the deletion mutant, the parent, or the revertant virus were approximately the same. The results suggested that gE and/or gI of EHV-1 promoted cell-to-cell spread of the virus, but that these glycoproteins were not involved in the process of virus maturation and release or in virus attachment and penetration. Subsequently, the virulence of mutant and revertant viruses was examined in young horses. No clinical signs were observed in six horses, including three colostrum-deprived foals inoculated intranasally with the deletion mutant virus, whereas three colostrum-deprived foals inoculated intranasally with the revertant virus manifested clinical signs typical for EHV-1 respiratory infection (i.e., pyrexia, nasal discharge, and swelling of submandibular lymph nodes). The results obtained from in vivo studies revealed that the EHV-1 mutant defective in both gE and gI genes was avirulent in young horses, suggesting that gE and/or gI of the EHV-1 have an important role in EHV-1 virulence. However, the EHV-1 mutant defective in both gE and gI genes induced only a partial protectivity in inoculated foals from manifestation of respiratory symptoms after challenge infection.

Animals↗
PubMed1998

Ezrin/radixin/moesin (ERM) proteins bind to a positively charged amino acid cluster in the juxta-membrane cytoplasmic domain of CD44, CD43, and ICAM-2.

CD44 has been identified as a membrane-binding partner for ezrin/radixin/moesin (ERM) proteins, plasma membrane/actin filament cross-linkers. ERM proteins, however, are not necessarily colocalized with CD44 in tissues, but with CD43 and ICAM-2 in some types of cells. We found that glutathione-S-transferase fusion proteins with the cytoplasmic domain of CD43 and ICAM-2, as well as CD44, bound to moesin in vitro. The regions responsible for the in vitro binding of CD43 and CD44 to moesin were narrowed down to their juxta-membrane 20-30-amino acid sequences in the cytoplasmic domain. These sequences and the cytoplasmic domain of ICAM-2 (28 amino acids) were all characterized by the positively charged amino acid clusters. When E-cadherin chimeric molecules bearing these positively charged amino acid clusters of CD44, CD43, or ICAM-2 were expressed in mouse L fibroblasts, they were co-concentrated with ERM proteins at microvilli, whereas those lacking these clusters were diffusely distributed on the cell surface. The specific binding of ERM proteins to the juxta-membrane positively charged amino acid clusters of CD44, CD43, and ICAM-2 was confirmed by immunoprecipitation and site-directed mutagenesis. From these findings, we conclude that ERM proteins bind to integral membrane proteins bearing a positively charged amino acid cluster in their juxta-membrane cytoplasmic domain.

Amino Acid Sequence↗
PubMed1998

Neuronal localization of fibroblast growth factor-9 immunoreactivity in human and rat brain.

Fibroblast growth factor-9 (FGF-9) is a relatively new member of the FGF family isolated from the conditioned medium of a human glioblastoma cell line as a secreting-type factor that exhibits a growth-stimulating effect on cultured glial cells. In order to elucidate the roles of FGF-9 in the central nervous system, we investigated in detail the distribution of FGF-9 proteins in the normal human and rat brains by immunohistochemistry using two different antibodies specific to FGF-9. In both human and rat, a strong expression of FGF-9 immunoreactivity was localized mainly in neurons throughout the normal brain. Immunoreactive glial cells were rarely encountered. In the human brain, strong and uniform immunoreactivity was observed in neurons of cerebral cortex, hippocampus, substantia nigra, motor nuclei of the brainstem, and Purkinje cell layer. A detailed mapping in the rat brain showed a distribution of FGF-9 immunoreactivity in a widespread population of neurons, though the intensity varied between different locations and even among the same nucleus. The most prominent expression in rat was observed in neurons of the mitral cell layer of the olfactory bulb, red nucleus, mesencephalic trigeminal nucleus, motor trigeminal nucleus, facial nucleus, reticular nucleus and Purkinje cell layer. These findings suggest that FGF-9 plays an important role in the central nervous system and may have a potential function closely connected to neurons in the normal brain.

Animals↗
PubMed1998

Identification of the lamina-associated-polypeptide-2-binding domain of B-type lamin.

Lamina-associated polypeptide (LAP)2, which directly interacts with B-type lamins and chromosomes, is an integral membrane protein specifically distributed along the inner nuclear membrane of the nuclear envelope. Multiple regions of its large nucleoplasmic domain promote this localization, including the first (residues 1-296) and the second (residues 298-409) halves of the LAP2 N terminus. The second half is involved in LAP2 association with the nuclear lamina [Furukawa, K., Panté, N., Aebi, U. & Gerace, L. (1995) EMBO J. 14, 1626-1636]. In this study to further define its role, we examined which domain of B-type lamin interacts with LAP2 by means of a binding assay with bacterially expressed proteins and a yeast two-hybrid system. We found that amino acids in the region of residues 78-258 of the lamin B1 rod domain directly bound with LAP2. The data suggest that LAP2 may modulate the assembly of nuclear lamins.

Binding Sites↗
PubMed1998

Binding capacity of FK506 binding protein after 2-hour hemispheric ischemia in gerbil brain.

The binding capacity of FK506 binding protein (FKBP) was examined after 2-h hemispheric ischemia in the gerbil brain in order to clarify the precise mechanism of the neuroprotective effects of FK506. Firstly, the FK506 binding was evaluated in vitro in the normal gerbil brain using 1 nM [3H]dihydro-FK506 as a specific ligand. FK506 binding sites were distributed in a rather homogeneous manner, although the greatest binding was noted in the hippocampus CA1. Secondly, Scatchard analysis demonstrated that the binding sites of FK506 could be composed of two components in each brain region. Thirdly, 18 Mongolian gerbils were divided into two groups: an ischemia group (n = 12) and a sham group (n = 6). The right common carotid artery was ligated to induce hemispheric ischemia for 2 h in the ischemia group. The local cerebral blood flow was measured at the end of the experiment by the [14C]iodoantipyrine method. The ligated animals with levels of local cerebral blood flow in the lateral nuclei of the thalamus of less than 50 ml/100 g/min were utilized as the ischemia group (n=6) for further data analysis. No significant differences in FK506 binding between the ischemia and sham groups were observed in any regions. The above data indicate that the binding capacity of FKBP tends to remain normal during 2-h ischemia, suggesting that FK506 may exert its neuroprotective effects through its binding to FKBP in the brain during the early phase of cerebral ischemia.

Animals↗