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Biomedical subjects

S Iwamoto

Publications and source records attributed to S Iwamoto.

At least 37 records · Page 2Linked to original sources
PubMed2000

The analysis of nucleotide substitutions, gaps, and recombination events between RHD and RHCE genes through complete sequencing.

We determined the entire nucleotide sequences of all introns within the RHD and RHCE genes by amplifying genomic DNA using long PCR methods. The RHD and RHCE genes were 57,295 and 57,831 bp in length, respectively. Aligning both genes revealed 138 gaps (insertions and deletions) below 100 bp, 1116 substitutions in all introns and all exons (coding region), and 5 gaps of over 100 bp. Homologies (%) between the RH genes were 93.8% over all introns and coding exons and 91.7% over all exons and introns. Various short tandem repeats (STRs) and many interspersed nuclear elements were identified in both genes. The proportions of Alu sequences in the RHD and RHCE genes were 25.9 and 25.7%, respectively and these Alu sequences were concentrated in several regions. We confirmed multiple recombinations in introns 1 and 2. Such multiple recombination, which probably arose due to the concentrations of Alu sequences and the high level of the homology (%), is one of most important factors in the formation and evolution of RH gene. The variability of the Rh system may be generated because of these features of RH genes. Apparent mutational hotspots and regions with low of K values (the numbers of substitutions per nucleotide site) caused by recombinations as well as true mutational hotspots may be found in human genome. Accordingly, in searching for and identifying single nucleotide polymorphisms (SNPs) especially in noncoding regions, apparent mutational hotspots and areas of low K values by recombination should be noted since the unequal distribution of SNPs will reduce the power of SNPs as genetic maker. Combining the complete sequences' data of both RH genes with serological findings will provide beneficial information with which to elucidate the mechanism of recombination, mutation, polymorphism, and evolution of other genes containing the RH gene as well as to analyze Rh variants and develop new methods of Rh genotyping.

Base Sequence↗
PubMed2000

A Japanese propositus with D-- phenotype characterized by the deletion of both the RHCE gene and D1S80 locus situated in chromosome 1p and the existence of a new CE-D-CE hybrid gene.

In a family study of a Japanese propositus with the D-- phenotype, the serological data of her D-- phenotype and those of her parents were discrepant. Gene analysis of the propositus showed a gross deletion of the RHCE gene and a new rearrangement of RHCE to yield the CE-D-CE hybrid. It was demonstrated that the hybrid CE-D-CE gene consisted of exon 1 from the RHCE gene, followed by exons 3 to 7 from the RHD gene and exons 8 to 10 from the RHCE gene. However, whether or not exon 2 of the RHD or the RHCE gene was contained in the CE-D-CE gene remained unclear. Moreover, spacer analysis between both RH genes and the family study suggested that the D-- gene complex from the paternal and maternal sides consisted of only the CE-D-CE hybrid gene and a single RHD gene, respectively. For the purpose of confirming the parent-child relationship, a paternity test using DNA fingerprint and polymerase chain reaction (PCR) analysis at the D1S80 locus were performed. DNA fingerprints with two kinds of DNA minisatellite probes (33.15 and 33.6) confirmed that the parent-child relationship in the D-- propositus was compatible. However, in the present case, at the D1S80 locus, the PCR product derived from the mother was lacking, thereby negating a parent-child relationship. It is probable that the RH genes and D1S80 locus exist in close proximity, because they are situated in chromosomes 1p 34.3-36.1 and 1p 36.1-36.3, respectively. These data suggested that at the stage of gametogenesis, both the RHCE gene and the D1S80 locus from the maternal side may have been deleted, thereby producing the D-- gene complex.

Chimera↗
PubMed2000

Absolute measurement of 166mHo radioactivity and development of sealed sources for standardization of gamma-ray emitting nuclides

Holmium-166m has a long half life (1200 yr) and emits a large number of gamma-rays between 80 and 1400 keV. These characteristics are very suitable for gamma-ray calibration sources, therefore, the absolute activity of 166mHo was measured and several sealed sources were produced to be used as reference sources for the secondary standardization systems for gamma-ray emitting nuclides. In this project, seven metal sealed sources and ten point sources were produced and several of these sources were transferred to the secondary standard laboratories to complete the traceability scheme.

Journal Article↗
PubMed2000

The application of direct immunofluorescence to intraoperative neurosurgical diagnosis.

A diagnostic problem can occur at the time of intraoperative consultation of neurosurgical tumors as to whether the tumor is of neuroectodermal origin or whether it represents an epithelial metastasis from another site. Intraoperative diagnoses based on hematoxylin and eosin stained frozen sections are often later confirmed by immunocytochemical analysis of formalin-fixed, paraffin-embedded tissue sections that are not available at the time of surgery. The objective of the current study was to demonstrate that the application of direct immunofluorescence to the intraoperative diagnosis of neurosurgical tumors would provide unequivocal, and nearly immediate results. This report describes a new application of an existing technique for an optimized, rapid procedure utilizing direct immunocytochemistry with fluorescence-labeled primary antibodies to analyze surgical biopsies intraoperatively. The examination of five neurosurgical biopsies established a neuroectodermal origin of three tumors via immunolabeling for glial fibrillary acidic protein (GFAP) and lack of labeling with keratin markers, whereas several metastatic lung carcinomas were identified by immunostaining for keratin, but not GFAP, markers. The results of the direct immunolabeling method were unequivocal and required only minutes. The same diagnoses were confirmed by standard immunocytochemical labeling of formalin-fixed, paraffin-embedded sections, though it required several days to obtain the results. Direct immunofluorescence using fluorescently conjugated primary antibodies is a practical and rapid method for deciding whether a neurosurgical tumor is a primary glial or an epithelial metastatic tumor in origin. It is the first reported application of the technique for this aspect of rapid neurosurgical diagnosis.

Antibodies, Monoclonal↗
PubMed2000

Effect of water content on dielectric relaxation of gelatin in a glassy state.

The dielectric properties of gelatin in the glassy state were measured from 100 Hz to 1 MHz over a temperature range of -20 to 60 degrees C. Samples with different water contents were prepared by varying the drying time for desalted gelatin solution; they were confirmed to be in the glassy state from DSC measurements. The dielectric relaxation (the decrease in dielectric constant, epsilon', and the maximum of the dielectric loss, epsilon' ') was observed for each sample; the relaxation time tau was evaluated from the peak of epsilon' '. The activation energy E obtained from an Arrhenius plot of tau decreased with increasing water content. On the basis of the order of magnitude of E, the dielectric relaxation observed was considered to be beta-relaxation reflecting the local motion of molecules. E and tau seem to describe the enhancement effect of water on the mobility of gelatin molecules in the glassy state; tau and E are considered to be suitable parameters for the characterization of the plasticizing effect of water on a glassy material.

Calorimetry, Differential Scanning↗
PubMed2000

The reconstitution of CD45RBhiCD4+ naive T cells is inversely correlated with donor age in murine allogeneic haematopoietic stem cell transplantation.

A high incidence of opportunistic infections after unrelated bone marrow transplantation has been reported. Delayed lymphocyte recovery may be associated with opportunistic infections. Immune reconstitution is influenced by recipient age and graft-vs-host disease (GVHD). In fact, children develop GVHD less frequently than adults. However, the role of donor age is largely unknown. We examined the effect of donor age on lymphocyte reconstitution after transplant. Three-month-old BALB/c recipient mice were lethally irradiated and transplanted with allogeneic haematopoietic stem cells from A/J donor mice of different ages, ranging from 0 d to 12 months. The recovery of absolute lymphocyte counts and those of CD3+ T cells, CD4+ T cells and CD45RBhi CD4+ naive T cells in the early post-transplant period correlated inversely with donor age. Recipient mice transplanted with haematopoietic stem cells from younger donors showed significantly higher survival rates and mitogenic responses than adult donors. As T cells, especially CD4+ naive T cells, play an important role in host defence, faster recovery of CD4+ naive T cells in younger donors may contribute to reduced mortality in the early post-transplant period. The results suggest that it could be better to choose a younger donor if sufficient cell dose is available.

Aging↗
PubMed2000

Genioglossus muscle activity during rhythmic open-close jaw movements.

The purpose of this study was to examine genioglossus muscle activity during rhythmic open-close jaw movements. The electromyographic activity of the genioglossus muscle was recorded with a bipolar fine-wire electrode in six healthy males. The electromyographic activities of the ipsilateral masseter and digastric muscles were simultaneously recorded with bipolar surface electrodes. The subjects were instructed to perform rhythmic open-close jaw movements in time with a metronome set at 23, 27, 33, 42 and 50 beats/min. In all of the subjects, rhythmic electromyographic activity of the genioglossus muscle was recorded in both the jaw-opening and jaw-closing phases. The activity of the genioglossus muscle was predominantly recorded in the jaw-opening phase in two subjects, and in the jaw-closing phase in two subjects. The burst duration of the electromyographic activity of the genioglossus muscle changed linearly in accordance with the cycle duration. However, the latency from the onset of the electromyographic activity of the masseter or digastric muscle to that of the genioglossus muscle was almost constant, independent of the cycle duration. Based on these findings, we conclude that the activity of the human genioglossus muscle is closely linked to that of masticatory muscles under the control of a closely related central pattern generator.

Adult↗
PubMed2000

Expression of survivin and its relationship to loss of apoptosis in breast carcinomas.

Aberrant inhibition of programmed cell death (apoptosis) prevents normal homeostasis and promotes tissue tumorigenesis, but whether it also influences the outcome of common cancers has remained arguable. The expression of a novel IAP apoptosis inhibitor, survivin, in breast cancer and its association with tumor cell apoptosis and overall prognosis were examined in this study. Immunohistochemical analysis showed that survivin expression was positive in 118 of 167 cases (70.7%) of breast carcinomas of histological stages I to IH. In contrast, no expression of survivin in adjacent normal tissue was detected. Although survivin expression was not correlated with p53 mutations, survivin-positive cases were strongly associated with bcl-2 expression (78.0% versus 47.5%; P = 0.0005) and reduced apoptotic index (0.62% +/- 0.51% versus 1.27% +/- 1.37%; P < 0.0001). In addition, patients with low apoptotic index (<0.52%) had worse survival rates than the group with high apoptotic index (> or =0.52%; P = 0.028), and multivariate Cox proportional hazard model analysis identified apoptotic index as an independent prognostic factor (P = 0.024). The results suggest that apoptosis inhibition by survivin, alone or in cooperation with bcl-2, is a significant prognostic parameter of worse outcome in breast carcinoma.

Aged↗
PubMed2000

Two-dimensional changes of muscle fiber types in growing rat hind limb.

In the present study, we examined the changes in two-dimensional distribution of fiber types in the whole area of the rat skeletal muscle and the effect of growth on this distribution. Muscles of rats aged 3 (body weight 58 g), 4 (89 g), 8 (276 g), 12 (312 g), 18 weeks (368 g), and 6 months (450 g) were stained for myofibrillar adenosine triphosphatase (mATPase) with preincubation at pH 4.35. Muscle fibers were classified into type I (slow oxidative), IIA (fast oxidative), IIB (fast glycolytic), and IIX (fast oxidative glycolytic). The x-y coordinates of each fiber were used to analyze the growth-related changes using an image analyzing system. In the tibialis anterior (TA) muscle, type I fibers were predominant in the deep and middle regions at 3 to 4 weeks of age, but became restricted to the deeper region with growth. In the extensor digitorum longus (EDL) muscle, type I fibers were predominant in the deep region at 3 to 8 weeks of age, but decreased gradually with growth and completely disappeared at 6 months of age. Compared with the TA and EDL, type I fibers of the soleus (SOL) muscle were spread throughout the muscle and the number of these fibers tended to increase with growth. Type IIA and IIX fibers of the SOL decreased in number and became restricted to the superficial region with growth. No type IIB fibers were detected in the SOL throughout life. Our results indicated that the growing process influences the distribution, proportion and characteristics of individual muscle fiber types in the rat hind limb muscles.

Adenosine Triphosphatases↗
PubMed1999

Conductance and relaxations of gelatin films in glassy and rubbery states.

The dielectric constant, epsilon', and the dielectric loss, epsilon'', for gelatin films were measured in the glassy and rubbery states over a frequency range from 20 Hz to 10 MHz; epsilon' and epsilon'' were transformed into M* formalism (M* = 1/(epsilon' - i epsilon'') = M' + iM''; i, the imaginary unit). The peak of epsilon'' was masked probably due to dc conduction, but the peak of M'', e.g. the conductivity relaxation, for the gelatin used was observed. By fitting the M'' data to the Havriliak-Negami type equation, the relaxation time, tauHN, was evaluated. The value of the activation energy, Etau, evaluated from an Arrhenius plot of 1/tauHN, agreed well with that of Esigma evaluated from the DC conductivity sigma0 both in the glassy and rubbery states, indicating that the conductivity relaxation observed for the gelatin films was ascribed to ionic conduction. The value of the activation energy in the glassy state was larger than that in the rubbery state.

Electric Conductivity↗
PubMed1999

Sequence analysis of the spacer region between the RHD and RHCE genes.

Numerous variants of the Rh blood group system, discovered by Levine and Stetson in 1939, have been detected and more than forty antigens have been identified. By performing the molecular genetic analysis of the introns as well as the exons in both RH genes, it was elucidated that Rh variants were generated by gene conversion or recombination, deletions, or mutations. For understanding the generation of many Rh variants and Rh antigens in detail, it is necessary to analyze not only the RHCE and RHD genes but also the structure and the physical distance between both these RH genes. In order to achieve the aforesaid purpose, the spacer region between the RHD and RHCE genes were amplified by the long PCR method. Therefore the full spacer region was determined to be 12159 bp in length and contained the Alu consensus sequences and the putative CpG island. It was probable that the duplication of both RH genes occurred within about 12 kb region. Analysis of the spacer region provides new information for the research on the transcription-control region, the molecular evolution of RH genes, Rh variants, and the deletion of the RHD gene in Rh blood group system.

Alu Elements↗
PubMed1999

The genomic organization of the partial D category DVa: the presence of a new partial D associated with the DVa phenotype.

Within the Rh blood group, the partial D phenotype is a well known RhD variant, that induces Rh-incompatible blood transfusion and hemolytic diseases in the newborn. The partial D category DVa phenotype (DVa Kou.) results from a hybrid of RhD-CE-D transcript. We demonstrated a genomic organization of the hybrid RHD-CE-D gene leading to the DVa phenotype, and showed that the DVa gene were generated from gene conversion between the RHD and the RHCE genes in relatively small regions. This study also revealed that the presence of a new partial D associated with the DVa phenotype, which we termed the DVa-like phenotype. In this phenotype, five RHD-specific nucleotides were replaced with the corresponding RHCE-derived nucleotides on the exon 5 of the RHD gene. In addition, two variants of the mutated RHD genes at nucleotide 697 were revealed in the RhD variant samples. These results will provide useful information for future research into the diversification of the Rh polypeptides.

Alleles↗