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Biomedical subjects

K Iso

Publications and source records attributed to K Iso.

At least 19 recordsLinked to original sources
PubMed2004

Primary cervical spinal epidural Extra-osseous Ewing's sarcoma.

Cases of primary spinal epidural Extra-osseous Ewing's sarcoma (EES) are rarely seen and a good prognosis for EES cannot be expected since a high incidence of local recurrence and metastasis frequently occur. We present a case of cervical spinal epidural EES in a 7-year-old girl with long survival after tumour resection. She also received adjuvant treatment with peripheral blood stem cell transplantation (PBSCT). This management successfully improved her condition and she was in complete remission without neurological deficit 60 months after surgery. Such a good prognosis of EES in the cervical spine is very rare. It is likely that magnetic resonance imaging (MRI) lead to a diagnosis of this rare type of EES at an early stage of the disease. PBSCT could be useful as an adjuvant to prolong the period of complete remission.

Child↗
PubMed2001

Simultaneous control of electrostatic micellar partition and electroosmotic flow-rate by anion-dominated partition into zwitterionic micelles.

The zeta potentials of zwitterionic micelles and capillary walls have been evaluated with capillary electrophoresis. The zeta potential of the micelles is predominantly determined by the nature of anions, while cations of identical valence have marginal effects; the linear relation has been found between the induced zeta potential and the hydration energy of an anion. The zeta potential of the capillary wall is also varied with anionic natures, and there is a good correlation between micellar and capillary wall zeta potential. This strongly suggests that the zeta potential of capillary walls is determined by the partition of anions into the surfactant layer formed on the capillary wall. Thus, we can simultaneously control both the electroosmotic flow-rate and micellar surface potential (in turn electrostatic interaction between micelles and ionic solutes) by varying the type and concentration of electrolytes. This idea has been applied to the separation of aromatic cationic solutes.

Anions↗
PubMed2001

Mother-to-infant transmission of TT virus in Japan.

OBJECTIVE: The TT virus (TTV) was detected for the first time by Nishizawa and Okamoto et al. in 1997 in the serum of a patient with post-transfusion hepatitis of unknown origin (non-A-non-G type). TTV was subsequently, also found in the serum of blood donors with no history of blood transfusion, although at a lower rate than among donors with a history of blood transfusion. In the present study, we determined the percentage of TTV carriers among pregnant women with no history of blood transfusion, and evaluated the possibility of mother-child transmission. METHODS: Blood was sampled from 300 normal pregnant women with no history of blood transfusion, 10 infants born by vaginal delivery from TTV-positive women, 10 infants born by abdominal cesarean section from TTV-positive women at both 5 days and 3 months after birth, and 10 infants born from TTV-positive women at 6 months after birth. Amniotic fluid and breast milk were sampled from 10 and 30 TTV-positive women, respectively. Informed consent was obtained from all women before sampling. TTV DNA was detected by the nested polymerase chain reaction (PCR) method. RESULTS: (1) Of the 300 normal pregnant women with no history of blood transfusion, 60 (20%) were TTV-positive. (2) All infants from TTV-positive mothers were TTV-negative at both 5 days and 3 months after birth, regardless of whether they were born by vaginal delivery or abdominal cesarean section. (3) Of the 10 infants who were born from TTV-positive mothers and examined 6 months after birth, 4 (40%) were TTV-positive. (4) Amniotic fluid from all 10 TTV-positive women was TTV-negative. (5) Breast milk from 7 (23.3%) of the 30 TTV-positive women was TTV-positive. CONCLUSION: TTV was detected in 20% of pregnant women with no history of blood transfusion, suggesting that TTV infection can occur through non- blood-mediated routes. The possibility of transfer of TTV into amniotic fluid was ruled out due to its absence in amniotic fluid samples. All infants from TTV-positive women were TTV-negative at both 5 days and 3 months after birth, regardless of whether they were born by vaginal delivery or abdominal cesarean section, suggesting that infection in the parturient canal or the pelvis is unlikely. Because TTV was detected in breast milk from TTV-positive women and some of their infants were TTV-positive, breast milk was thought to be a mother-child infection route. These findings suggest that horizontal infection is more likely than vertical infection in mother-child transmission of TTV.

Amniotic Fluid↗
PubMed1989

[Influence of tooth contacts on masseter and temporal muscle activity. 1. Total activity and its ratio to maximum biting activity in intercuspal position (IP ratio)].

14 natural dentitioned subjects with no signs of TMJ disorders, aged 19-58, were used in this study. They were divided into three groups according to their occlusal guidance. One is canine guidance group (CG group), the other is group function group (GF group), and the last is group having non-working side contacts (FB group). All subjects were asked to perform maximum biting in 1) intercuspal position (IP), 2) right lateral position (rLP), 3) left lateral position (lLP), 4) retruded position (RP), and 5) protruded position (PP). EMG recordings of right and left masseter, anterior and posterior temporal muscles from pairs of surface electrodes were taken in each occluded position. The results were as follows: 1) Total integrated EMG activity of FB group was approximately equal in any occluded position, whereas that of CG and GF group varied from position to position. 2) EMG patterns in rLP and lLP of CG group were obviously different from those of GF group. Ratio to maximum biting in IP of CG group in rLP and lLP were significantly small, approximately half of GF group.

Adolescent↗
PubMed1984

Magnesium binding and conformational change of DNA in chromatin.

The structure of chromatin in the presence of Mg2+ ions was examined by circular dichroism and equilibrium dialysis. Circular dichroism (CD) shows that above 260 nm the intensity of the spectrum of DNA in nucleoproteins decreases as the Mg2+ concentration increases. This change is an intrinsic characteristic of DNA since it is also observed in protein-free DNA and has been attributed to a change in the winding angle of base pairs around the DNA axis. Some structural elements of the DNA in the nucleosome core, therefore, are as movable as those of protein-free DNA. The basic organization of H1-depleted chromatin, 146 base pairs (bp) of DNA wound around core histones and a residual 49 bp in the linker region in the repeating unit, is maintained both in the presence and in the absence of Mg2+ ions, as shown by the fact that the CD spectrum of H1-depleted chromatin has the same type of linear combination between the spectrum of protein-free DNA and that of the nucleosome core in 0.2 mM MgCl2-10 mM triethanolamine (pH 7.8) as it has in 1 mM ethylenediaminetetraacetic acid-10 mM tris(hydroxymethyl) aminomethane (pH 7.8). The ellipticity of chromatin shows a smaller decrease relative to the other nucleoproteins and protein-free DNA upon the addition of Mg2+ ions. Therefore, some structural elements of chromatin are apparently somewhat protected against the conformational change induced by these ions. The spectrum of chromatin becomes almost indistinguishable from that of H1-depleted chromatin in 0.2 mM MgCl2.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Graphic display of nucleic acid structure by a microcomputer.

A microcomputer program for the display of a three dimensional structure of a nucleic acid and a protein has been developed. This program can generate a wire model and a ball and stick model on a color CRT display. The phosphate atoms on the backbone, backbone, bases and all atoms can be respectively displayed. Rotation and enlargement of a partial structure is easily accomplished.

Computers↗
PubMed1983

Internal motion of deoxyribonucleic acid in chromatin. Nanosecond fluorescence studies of intercalated ethidium.

We have investigated the internal motions of DNA in a nucleosome core particle and chromatin by measuring the nanosecond fluorescence depolarization of intercalated ethidium. Assuming that the observed anisotrophy decay originates from the torsional motion of DNA, we have analyzed the dynamics of DNA in a nucleosome core particle and in chromatin in detail. The results suggest that DNA in a nucleosome core particle has a torsional rigidity similar to that of DNA in solution and that even at the point of the ionic bonds between DNA and a histone octamer the torsional motion of DNA is not completely inhibited. On the other hand, the dynamics of linker DNA in chromatin were found to reflect the overall structural state of the chromatin: the motion of linker DNA was suppressed as the structure of chromatin turned from an extended state to a condensed one. This indicates that, in solenoidal chromatin, nucleosome movements in chromatin are largely suppressed. Furthermore, the result may suggest that the torsional rigidity of linker DNA is increased as it is forced to bend in solenoidal chromatin.

Animals↗
PubMed1983

Dynamics of DNA in chromatin and DNA binding mode to core protein.

We have studied the dynamics of DNA in nucleosome core particles and in the linker region of chromatin using nanosecond fluorescence anisotropy decay measurements of intercalated ethidium. DNA in the core undergoes torsional motions to the same extent as the linker DNA in extended chromatin. We therefore concluded that the binding of DNA to the histone octamer is relatively weak or limited to a few points; stretches of at least several tens of base pairs exist which can move as freely as DNA in solution.

Animals↗
PubMed1982

Chemical evidence for the capsomeric structure of phage q beta.

Novel capsomeric complexes, pentamers and hexamers were detected as chemical entities in phage Q beta. Both were composed of identical protein subunits and stabilized by intermolecular disulphide bonds. Their numbers per particle were about 12 for pentamers and about 20 for hexamers--consistent with theoretical expectation from the quasi-equivalent packing of 180 identical subunits in a coat protein shell.

Capsid↗
PubMed1982

Lifetime of tyrosine fluorescence in nucleosome core particles.

The fluorescence intensity and fluorescence lifetime of the tyrosine residues in calf thymus nucleosome core particles have been determined as functions of the ionic strength of the solvent. For interpreting the results, in the first approximation, the 30 tyrosine residues involved in the particle are classified into two groups. About 12 belong to class I; they are distributed in the protein core with an average distance of 2.0 nm from its center. In the intact particle (in 20 mM to 0.4 M salt solution), a Förster-type energy transfer is considered to take place from these class-I tyrosine residues to the DNA bases, but this no longer occurs on elevating the salt concentration to about 1.4 m. The remaining tyrosine residues (about 18, called class II) are considered to be involved in hydrogen bonds or in some other intramolecular interactions in the intact core particles, so that their fluorescence is completely quenched. On elevating the salt concentration to 2.0 M, this quenching is partially removed. Implications of these dynamic and static quenching are discussed in terms of the structure of the core particle.

Animals↗
PubMed1975

Studies on ribosomal ribonucleic acid from yeast. III. Secondary structure of 18 and 26S yeast ribosomal RNA's and their complex: circular dichroism and infrared analyses.

Circular dichroism (CD) and infrared (IR) spectroscopic analyses were performed of 26 and 18S yeast ribosomal RNA's (rRNA) and their specific complex, 30S RNA. The molecular ellipticity coefficients [thota] of 18, 26, and 30S rRNA's were 2.72, 2.63, and 2.65X10(4) degree-cm2/decimole at 264 nm, respectively. The base-pairing contents of 18, 26, and 30S rna's determined by iC), and 70% (32% AU, 38% GC), respectively. These results suggest that 18 and 26S rRNA have very similar secondary structures, and that 30S rna may have a slightly higher base-pairing content than the estimated sum of those of 18 and 26S rRNA's. The biological significance of this phenomenon is discussed in this report.

Binding Sites↗