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Biomedical subjects

T Komiya

Publications and source records attributed to T Komiya.

At least 55 records · Page 3Linked to original sources
PubMed1998

Characterization of the initial steps of precursor import into rat liver mitoplasts.

Mitochondria have two independent protein-import machineries, one in the outer membrane (the Tom system) and the other in the inner membrane (the Tim system). Here, we have characterized the initial steps of precursor import into rat liver mitoplasts. The import reaction was separated into two stages, consisting of precursor binding to the mitoplasts at 0-10 degreesC, and a subsequent chase reaction at 30 degreesC. This assay revealed four distinct precursor-import steps: DeltaPsi-dependent initial binding of the precursor, precursor transfer to the Tim23-Tim17 stage, DeltaPsi-dependent translocation of the presequence across the inner membrane, and the complete translocation of the mature portion of the precursor. Antibodies against the intermembrane space domain of Tim23 inhibited neither the precursor binding nor the subsequent translocation of the presequence across the inner membrane. In contrast, the antibodies inhibited the complete translocation of the mature domain of the precursor across the inner membrane. Immunoprecipitation with anti-Tim23 IgGs revealed that the precursor-Tim23 complex increased with time and temperature after the initial targeting of the precursor to the mitoplasts. These results suggest that the precursor is first targeted to the inner membrane component DeltaPsi-dependently, then transferred to the Tim system consisting of Tim23-Tim17, and finally imported into the matrix.

Amino Acid Sequence↗
PubMed1998

Induction of protection against tetanus toxin in mice by tetanus toxoid-liposome conjugate.

Tetanus toxoid (Ttd) was coupled to liposomes via glutaraldehyde. Intraperitoneal injection in BALB/c mice with Ttd-liposomes induced a substantial amount of anti-Ttd IgG antibody production and an extremely low level of anti-Ttd IgE antibody production. Mice immunized with Ttd-liposomes were successfully protected against a subsequent challenge with a lethal dose of tetanus toxin (Ttx). On the other hand, aluminum hydroxide-adsorbed Ttd (Ttd-alum) and plain Ttd solution induced the production of both IgG and IgE antibodies against Ttd. Moreover, secondary immunization with Ttd-liposomes in mice, in which anti-Ttd IgE antibody production was induced by Ttd-alum led to enhanced anti-Ttd IgG and a limited anti-Ttd IgE antibody production. When Ttd-liposome preparation was lyophilized, the efficacy of Ttd-liposomes was maintained for 6 months at 37 C, suggesting that this vaccine preparation would be stable without refrigeration. These results demonstrate the potential ability of Ttd-liposome conjugates to produce a tetanus vaccine which provides protection against (Ttx) while inducing the least amount of anti-Ttd IgE antibodies.

Animals↗
PubMed1998

Minimum structure of diapause hormone required for biological activity.

Diapause hormone is a 24-amino acid peptide amide, and its C-terminal penta-peptide amide structure of FGPRL-NH2 is believed to be essential for biological activity. The penta-peptide amide, the shorter peptide amides, and their derivatives and analogs were prepared to determine the minimal structure for biological activity. The C-terminal amide group of penta-peptide amide was not replaced with the other functional groups, but Gly, the 4th amino acid from the C terminal, could be substituted with an other amino acid while maintaining the biological activity. The shorter peptide amide, PRL-NH2, possessed low but significant activity, indicating the minimum structure of diapause hormone. By modifying its N-terminal, the aromatic ring of Phe is shown to enhance the activity of PRL-NH2.

Animals↗
PubMed1998

Magnetic resonance cisternography for visualization of intracisternal fine structures.

OBJECT: To assess its usefulness in demonstrating cisternal anatomy, the authors investigated magnetic resonance (MR) cisternography in which a heavily T2-weighted turbo spin-echo method was used to visualize normal anatomical fine structures and lesions in the basal cisterns in 20 healthy volunteers and 43 patients. The authors applied peripheral pulse gating, which had been optimized to reduce artifacts in the cisterns attributable to cerebrospinal fluid (CSF) flow. METHODS: The detectability of each cranial nerve was determined in healthy volunteers. The first, second, and third nerves and the seventh-eighth nerve complex were clearly visualized in all participants; the fifth nerve was clearly seen in 80% and the sixth cranial nerve in 50%. The fourth nerve and the ninth through 12th nerves were difficult to identify individually, except in some volunteers. To reduce artifacts caused by fast CSF flow, we determined the delays as a function of the time elapsed between two consecutive peaks of pulse wave in a peripheral pulse gate (P-P interval) at which there was reversal of flow direction to minimize the CSF flow-related artifact. Using peripheral pulse gating and a time delay of 30% of the R-R interval, the authors succeeded in minimizing the CSF flow-related artifacts. Magnetic resonance cisternography appears to be very useful for demonstrating intracisternal fine anatomy and enhancing the contours of the juxtacisternal lesion. A minute amount of CSF interposed between lesions and normal structures such as nerves, vessels, or bone structures can be detected by means of this sequence. In patients with facial spasm, axial images and oblique coronal images obtained in a plane parallel to the seventh-eighth cranial nerve complex demonstrated vascular compression in all 13 patients. The MR cisternography finding of compression was confirmed in all nine patients who underwent microvascular decompression. CONCLUSIONS: Magnetic resonance cisternography appears to show great promise for evaluation of patients with neurovascular compression or tumors in and around the basal cisterns; the procedure adds only a small amount of imaging time.

Adult↗
PubMed1998

Black tea theaflavins induce programmed cell death in cultured human stomach cancer cells.

The exposure of human stomach cancer KATO III cells to black tea theaflavin extract, free theaflavin, and theaflavin digallate that are main components of the extract, led to both growth inhibition and the induction of programmed cell death (apoptosis). Morphological changes showing apoptotic bodies were observed in the cells treated with black tea theaflavin extract, theaflavin and theaflavin digallate. The fragmentations by these theaflavin compounds of DNA to oligonucleosomal-sized fragments that are characteristics of apoptosis were observed to be concentration- and time-dependent. These data suggest that drinking of black tea in large amounts is recommended to protect humans from stomach cancer.

Apoptosis↗
PubMed1998

Honokiol induces apoptosis in human lymphoid leukemia Molt 4B cells.

The exposure of human lymphoid leukemia Molt 4B cells to honokiol led to both growth inhibition and the induction of apoptosis. Morphological change showing apoptotic bodies was observed in the cells treated with honokiol. The fragmentation by honokiol of DNA to oligonucleosomal-sized fragments that are characteristics of apoptosis was observed to be concentration- and time-dependent. These findings suggest that growth inhibition by honokiol of Molt 4B cells results from the induction of apoptosis in the cells.

Antineoplastic Agents, Phytogenic↗
PubMed1998

The similarity between parents and offspring in facial soft tissue: a frontal-view study.

Similarities between parents and their offspring in facial soft tissue features were investigated. Fifty boys and fifty girls aged 9-10 years, excluding those with congenital anomalies, were selected. Frontal photographs of the family (father, mother and offspring) were taken and twenty-nine landmarks located on each enlarged tracing made from a photograph. Each landmark was digitised into (x, y) co-ordinate values from which the area and linear ratio dimensions were calculated and statistically evaluated. Results indicated that: (1) The nose was the feature that was most significantly correlated between parents and offspring. (2) The similarities between parents and offspring were closer for the relative positions of other features to the eyes than for individual features of the face. In general, the correlations between 'midparents' (the mean value of both parents) and offspring were higher than those between one parent and offspring. (3) The correlations between parents and offspring for size were higher than those for shape. (4) The similarities between mothers and offspring were closer than those between fathers and offspring. Furthermore: among four pairs of father/son, father/daughter, mother/son and mother/daughter, the mother/daughter pair had the highest correlation and the father/son pair had the lowest, which appears to be related to X-chromosome inheritance.

Adult↗
PubMed1998

[Prognostic significance of alterations in telomeric repeat length in patients with pathological stage I-II non-small cell lung cancer].

UNLABELLED: The purpose of this study was to evaluate the correlation between alteration in telomere length and prognosis in patients with pathological stage I-II non-small cell lung cancer. We measured telomeric repeat length and telomerase activity by use of southern blot analysis of terminal restriction fragments and a non-radioactive ELISA-based assay, respectively. RESULTS: Alterations in TRF lengths were present in 17(29.8%) of 57 patients. Patients with altered TRF length had significantly shorter survival than did patients without (P = 0.0051). In multivariate analysis, only alteration in TRF length independently correlated with shortened survival (P = 0.0033).

Adult↗
PubMed1998

[Hyponatremia in Duchenne muscular dystrophy on mechanical ventilation].

To evaluate the pathomechanism of hyponatremia occasionally seen in Duchenne muscular dystrophy (DMD) on intermittent positive pressure ventilation (IPPV), we performed a comparative study on 26 DMD patients, 7 IPPV in trachetomized intermittent positive pressure ventilation (TIPPV), 6 nasal intermittent positive pressure ventilation (NIPPV), 6 cuirass respirator (CR), and 7 spontaneous breathings (SB). We followed fluctuation of serum sodium levels for several years. Since the serum sodium level was gradually reduced with years on mechanical ventilation, we speculated positive relationship between hyponatremia and antidiuretic hormone (ADH) secretion. Serum sodium levels of 135.6 +/- 2.8 mEq/L in average on IPPV (TIPPV + NIPPV) patients was significantly lower than the levels of 137.8 mEq/L +/- 0.98 on CR patients and 138.8 +/- 0.69 mEq/L on SB patients. Plasma ADH levels in IPPV patients were not reduced when plasma osmolarity was less than 280 mOSm/L. Previous reports showed that ADH was inappropriately secreted only during IPPV with positive end expiratory pressure (PEEP). Ours is the first report of inappropriate secretion of ADH during IPPV without PEEP. It becomes clear that inappropriate ADH secretion is one of the causes of hyponatremia in DMD, though the exact mechanism is not clear. We should bear in mind the change of serum electrolyte level in ventilated DMD patients, especially patients on antidepressant known to release of ADH.

Adult↗
PubMed1998

[Emergent operation for acute Stanford type A aortic dissection].

Results of emergent surgery for acute Stanford type A aortic dissection are still poor. We reviewed our cases to find out how we could ameliorate surgical results. In the past five years, 36 patients with type A aortic dissection underwent emergent surgery. The operation was started within six hours from the onset of symptoms in 16 patients. The extent of aortic replacement was just beyond the entry-bearing portion. The operation was performed with the aid of open distal anastomosis and selective cerebral perfusion. Operative death occurred in one patient. Postoperative complications developed frequently. Respiratory failure, renal dysfunction and low cardiac output syndrome were most frequent. Their co-risk factor was perioperative bleeding which was related to young age, long operation time, arch replacement, additional procedure and failure of the entry site resection. Some modification of the suturing method might reduce hemorrhage. Prompt surgery following the diagnosis and appropriate selection of surgical tactics and anastomosis technique in order to reduce bleeding is essential to improve surgical results of acute type A aortic dissection.

Acute Disease↗
PubMed1998

Cochlear neuronal loss are determined by use of a neurofilament protein antibody in cases of bilateral profound deafness.

The temporal bones of two patients with profound bilateral deafness from infancy were studied immunohistochemically, using a neurofilament protein antibody to detect the cochlear neuronal elements. One patient exhibited Mondini dysplasia of the inner ear, with the organ of Corti almost completely deteriorated. The other patient is the first reported case involving complete aplasia of the organ of Corti in all turns. In both cases, the immunohistochemical staining clearly revealed a severe reduction in the number of afferent neurons, such as dendrites, spiral ganglion cells and cochlear axons. The number of efferent spiral bundles in the osseous spiral lamina and intraganglionic portion also decreased in parallel with the reduction in the number of cochlear afferent neurons. Our results are inconsistent with previously reported cases of presbycusis and acquired deafness induced by the measles virus, in which efferent neurons were preserved while afferent neurons degenerated. The loss of both the efferent and afferent neurons might be characteristics of congenital deafness.

Aged↗
PubMed1997

A large-scale in situ hybridization system using an equalized cDNA library.

We have developed a large-scale in situ hybridization system in which all the procedures are carried out on a 96-well format: digoxigenin-labeled probes were synthesized from PCR-amplified templates, sections were mounted on 96-well plates, and hybridization and immunohistochemistry protocols were carried out in each well of the plates. This system in combination with equalized (normalized) cDNA library as the source for the probes enables us to identify the cellular distribution of many mRNAs in various tissues rapidly and efficiently. Thus, this system may be a novel cloning method of identify genes differentially expressed in many tissues. In addition, this system has a potential to be automated.

Animals↗
PubMed1997

Large-scale immunohistological staining using polyethylene glycol-embedded sections mounted on 96-well plates for monoclonal antibody screening.

We have developed a rapid, large-scale immunohistological staining method for monoclonal antibody screening. Sections embedded in polyethylene glycol are mounted on 96-well plates and then subjected to immunological procedures using a 96-well format. With this method, we can prepare 10 plates (960 samples) in 1 day and then perform immunohistological procedures in 1 day by using an enzyme-linked immunosorbent assay-like 96-well format. Thus, we can avoid difficulties seen in conventional immunohistological methods that use sections mounted on glass slides. This method offers high-throughput screening of monoclonal antibodies. In addition, it has the potential of being automated.

Animals↗
PubMed1997

Analysis of the functional domain of the rat liver mitochondrial import receptor Tom20.

Tom20 is an outer mitochondrial membrane protein and functions as a component of the import receptor complex for the cytoplasmically synthesized mitochondrial precursor proteins. It consists of the N-terminal membrane-anchor segment, the tetratricopeptide repeat (TPR) motif, a charged amino acids-rich linker segment between the membrane anchor and the TPR motif, and the C-terminal acidic amino acid cluster. To assess the functional significance of these segments in mammalian Tom20, we cloned rat Tom20 and expressed mutant rat Tom20 proteins in Deltatom20 yeast cells and examined their ability to complement the defects of respiration-driven growth and mitochondrial protein import. Tom20N69, a mutant consisting of the membrane anchor and the linker segments, was targeted to mitochondria and complemented the growth and import defects as efficiently as wild-type Tom20, whereas a mutant lacking the linker segment did not. In vitro protein import into mitochondria isolated from the complemented yeast cells revealed that the precursor targeted to yeast Tom70 was efficiently imported into the mitochondria via rat Tom20N69. Thus the linker segment is essential for the function of rat Tom20, whereas the TPR motif and the C-terminal acidic amino acids are not.

Amino Acid Sequence↗
PubMed1997

Binding of mitochondrial precursor proteins to the cytoplasmic domains of the import receptors Tom70 and Tom20 is determined by cytoplasmic chaperones.

We have reconstituted the early steps of precursor targeting to mitochondria in a defined and soluble system consisting of the cytosolic domains of the yeast mitochondrial import receptors Tom20 and Tom70, precursor to bovine adrenal adrenodoxin (which has a cleavable targeting signal) and rat liver cytosolic chaperones hsp70 and mitochondrial import-stimulating factor (MSF). The Tom70 domain only bound the precursor in the presence of MSF, yielding a precursor-MSF-Tom70 complex; ATP hydrolysis by MSF released MSF and generated a precursor-Tom70 complex whose formation was inhibited by an excess of a functional presequence peptide, but not by 150 mM NaCl. In the presence of the Tom20 domain, ATP caused transfer of the precursor from the precursor-MSF-Tom70 complex to Tom20. The Tom20 domain alone only bound the precursor in the presence of hsp70; hsp70 itself was not incorporated into the resulting complex. Formation of the Tom20-precursor complex was inhibited by excess presequence peptide or by 150 mM NaCl. Similar results were obtained with the ADP/ATP carrier and porin precursors, which both lack a cleaved targeting signal. Correct targeting of a precursor to mitochondrial import receptors thus requires cytosolic chaperones, irrespective of the presence or absence of a cleavable presequence.

14-3-3 Proteins↗
PubMed1997

Metaxin is a component of a preprotein import complex in the outer membrane of the mammalian mitochondrion.

Metaxin, a novel gene located between the glucocerebrosidase and thrombospondin 3 genes in the mouse, is essential for survival of the postimplantation mouse embryo. In this study, the subcellular location, domain structure, and biochemical function of metaxin were investigated. Anti-recombinant metaxin antibodies recognized 35- and 70-kDa proteins in mitochondria from various tissues; the 35-kDa protein is consistent in size with the predicted translation product of metaxin cDNA. When metaxin cDNA was transfected into COS cells, immunofluorescence staining demonstrated that the protein is located in mitochondria. Metaxin contains a putative mitochondrial outer membrane signal anchor domain at its C terminus, and a truncated form of metaxin lacking this signal anchor domain had a reduced association with mitochondria. In addition, metaxin was highly susceptible to proteases in intact mitochondria. We therefore conclude that metaxin is a mitochondrial protein that extends into the cytosol while anchored into the outer membrane at its C terminus. In its N-terminal region, metaxin shows significant sequence identity to Tom37, a component of the outer membrane portion of the mitochondrial preprotein translocation apparatus in Saccharomyces cerevisiae, but important structural differences, including apparently different mechanisms of targeting to membranes, also exist between the two proteins. Given the similar subcellular locations of metaxin and Tom37, the possible role of metaxin in mitochondrial preprotein import was investigated. Antibodies against metaxin, when preincubated with mitochondria, partially inhibited the uptake of radiolabeled preadrenodoxin into mitochondria. Metaxin is therefore the second mammalian component of the protein translocation apparatus of the mitochondrial outer membrane to be characterized at the molecular level and the first for which an inherited mutation has been described. The early embryonic lethal phenotype of mice lacking metaxin demonstrates that efficient import of proteins into mitochondria is crucial for cellular survival. The characterization of metaxin provides an opportunity to elucidate similarities and possible differences in the mechanisms of protein import between fungi and mammals and in the phenotypes of fungi and mammals lacking mitochondrial import receptors.

Amino Acid Sequence↗
PubMed1997

Transcutaneous needle biopsy of the lung.

PURPOSE: To evaluate the usefulness of transcutaneous needle biopsy (TCNB). MATERIAL AND METHODS: From May 1988 to December 1994, we performed TCNB under fluoroscopic control in 408 patients with mass lesions of the peripheral lung. The Surecut needle (1.5 mm) was selected mainly because of its ability to obtain specimens large enough for histological examination. Of the 408 patients, 286 had had previous bronchofiberscopic examinations but no definite diagnosis had been reached. RESULTS: A definite diagnosis was obtained by TCNB in 305 (74.7%) of 408 cases (251 malignant neoplasms, 54 benign lesions). In malignant neoplasms, the pathological diagnosis based on cytology and histology together was more reliable than that based on cytology alone. Although the complications of this procedure (such as pneumothorax) were within the range of acceptability, care should be taken to avoid air embolism and the seeding of cancer cells along the needle tract. CONCLUSION: TCNB with the Surecut needle is a useful procedure with relatively low risk.

Biopsy, Needle↗