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Biomedical subjects

S Ichimura

Publications and source records attributed to S Ichimura.

At least 37 records · Page 2Linked to original sources
PubMed1998

Effect of exercise on tibial and lumbar vertebral bone mass in mature osteopenic rats: bone histomorphometry study.

The effect of moderate running exercise on tibial and lumbar vertebral bone mass was examined in mature osteopenic rats by bone histomorphometry. Ten 37-week-old female Wistar rats, with bone loss resulting from being fed a relatively low-calcium diet for 14 weeks after ovariectomy at the age of 23 weeks, were randomly divided into two groups of five animals each; control and exercise groups. The exercise consisted of treadmill running at 12 m/min for 1 h per day on 5 days per week for 12 weeks. During the exercise period, all animals were fed a standard calcium diet. After 12 weeks of exercise, bone histomorphometry was evaluated for cancellous bone (secondary spongiosa) of the proximal tibia and the fourth lumbar vertebra and for cortical bone of the tibial shaft. The findings suggested that in the mature osteopenic rat, there was a beneficial effect of moderate running exercise with adequate calcium intake on bone mass only in a weight-bearing long bone, the tibia. The mechanism for increased bone mass appeared to be both decreased bone resorption and increased bone formation in cancellous bone and increased bone formation in cortical bone.

Analysis of Variance↗
PubMed1998

Higher frequency of concerted evolutionary events in rodents than in man at the polyubiquitin gene VNTR locus.

The polyubiquitin gene is an evolutionarily conserved eukaryotic gene, encoding tandemly repeated multiple ubiquitins, and is considered to be subject to concerted evolution. Here, we present the nucleotide sequences of new alleles of the polyubiquitin gene UbC in humans and CHUB2 in Chinese hamster, which encode a different number of ubiquitin units from those of previously reported genes. And we analyze the concerted evolution of these genes on the basis of their orthologous relationship. That the mean of the synonymous sequence difference Ks which is defined as the number of synonymous substitution relative to the total number of synonymous sites, within the UbC and CHUB2 genes (0.192 +/- 0.096) is significantly less than Ks between these genes (0.602 +/- 0.057) provides direct evidence for concerted evolution. Moreover, it also appears that concerted evolutionary events have been much more frequent in CHUB2 than in UbC, because Ks within CHUB2 (0.022 +/- 0.018) is much less than that within UbC (0.362 +/- 0.192). By a numerical simulation, postulating that the major mechanism of concerted evolution in polyubiquitin genes is unequal crossing over, we estimated the frequency of concerted evolutionary events of CHUB2 at 3.3 x 10(-5) per year and that of UbC at no more than 5.0 x 10(-7) per year.

Amino Acid Sequence↗
PubMed1998

Effects of exercise on bone mineral density in mature osteopenic rats.

Dual-energy X-ray absorptiometry (DXA) was used to examine the effects of quantitative application of treadmill running exercise on bone mineral density (BMD) of the tibia and the fourth and fifth lumbar (L4 + L5) vertebrae in mature osteopenic rats. Twenty 37-week-old rats with bone loss, resulting from feeding a relatively low calcium diet for 14 weeks after ovariectomy at the age of 23 weeks, were divided into four groups of five rats each according to the intensity and duration of the exercise: 12 m/minute, 1 h/day in group EX1; 18 m/minute, 1 h/day in group EX2; 12 m/minute, 2 h/day in group EX3; and sedentary control in group CON. With a standard calcium diet, the exercise was performed 5 days a week for 12 weeks, and the BMD of both the right tibia and the L4 + L5 vertebrae was measured using DXA at weeks 0, 4, 8, and 12. At the end of 12 weeks of exercise, the right femur and the L5 vertebra were dissected and the mechanical strength was measured using a three-point bending test and a compression test, respectively. After 12 weeks of exercise, a significant increase in the tibial BMD was observed in only group EX1 compared with that in group CON (p = 0.0039, by two-way analysis of variance). However, any significant increase in the L4 + L5 vertebral BMD was not observed in any exercise groups compared with that in the control group. While a maximum breaking force of the femoral shaft in group EX1 was significantly greater than that in group CON (p < 0.05, by Mann-Whitney's U-test), that in groups EX2 and EX3 did not significantly differ from that in group CON. However, there was no significant difference in a maximum breaking force of the L5 vertebral body among all the exercise and control groups. These results indicated that the beneficial effects of treadmill running exercise under a standard calcium diet were recognized only in the weight-bearing bones of the mature osteopenic rats resulting from estrogen deficiency and inadequate calcium intake only when an optimal level of exercise was applied.

Absorptiometry, Photon↗
PubMed1998

Effects of moderate intensity exercise on tibial bone mass in mature ovariectomized rats: bone histomorphometry study.

The effects of moderate intensity exercise of different duration on the cancellous and cortical bone mass of the tibia were investigated in mature ovariectomized rats by bone histomorphometry. A total of twenty 23-week-old female Wistar rats were used in this study. Ovariectomy (OV) was performed on 15 animals, and they were divided into three groups of five animals each: an OV group, an OV + exercise for 30 min a day (EX30) group and an OV + EX60 group. The other 5 animals served as a sham-operated (SH) control group. The exercise consisted of treadmill running at 16 m/min and was performed 5 days a week for 12 weeks after the operation. After 12 weeks of exercise, bone histomorphometry was used to evaluate the cancellous bone (secondary spongiosa) of the proximal tibia and the cortical bone of the tibial shaft. The OV group showed a significant decrease in cancellous bone volume, with increased resorption and formation, compared to the SH group (P < 0.01). Although the OV + EX30 group showed a significant increase in cancellous bone volume, with decreased resorption and increased osteoblastic activity, compared to the OV group (P < 0.05), cancellous bone volume in the OV + EX30 group remained significantly lower than that in the SH group (P < 0.05). There was not a significant difference in cortical bone area between the OV group and the SH group, whereas the OV + EX30 group showed a significant increase in cortical bone area, with decreased resorption on the endosteal surface, compared to the OV group (P < 0.05). There were no significant differences in cancellous bone volume or cortical bone area between the OV group and the OV + EX60 group. The data suggest that moderate intensity exercise of appropriate duration may attenuate ovariectomy-induced cancellous bone loss and increase cortical bone mass in mature ovariectomized rats.

Animals↗
PubMed1997

Quantification of 1,5-anhydro-D-glucitol in urine by automated borate complex anion-exchange chromatography with an immobilized enzyme reactor.

HPLC using a borate form of a strongly anion-exchange resin column and an immobilized enzyme reactor for colorimetric detection was used to quantify urinary 1,5-anhydro-D-glucitol. Urine samples were introduced into the system every 7 min without any pretreatment, and after separation of interfering substances in the column, 1,5-anhydro-D-glucitol was successively detected. Quantitative determination of urinary 1,5-anhydro-D-glucitol was possible within the 1.2-300 micromol/l range. The coefficient of variance was less than 3% and the correlation between results obtained with our system (y) and those obtained by gas chromatography-mass spectrometry (x) was y=0.983x-1.287 micromol/l (n=42, r=0.998).

Borates↗
PubMed1997

A major non-LTR retrotransposon of Bombyx mori, L1Bm.

Repetitive sequences with oligo A tails were observed in Dra1 fragments of Bombyx mori genomic DNA. The full sequence of the element, an abundant non-LTR retrotransposon of B. mori, was determined by assembling inner restriction fragments. This element, designated L1Bm, contained two ORFs encoding a gag-like protein and reverse transcriptase (RT), respectively. An endonuclease domain was identified at the N-terminus of the RT sequence. The homology search of the amino acid sequences revealed that L1Bm belongs evolutionally to the same family as various other non-LTR retrotransposons of Drosophila and Mosquito. On the other hand, L1Bm resembles the L1 element of human genome in its high copy number and its frequent truncation at the 5'-side. Some units of the histone gene repeat in B. mori possess complete L1Bm elements in a 3'-flanking region of H2b.

Amino Acid Sequence↗
PubMed1996

Comparison of the 5' upstream region of the evolutionarily equivalent polyubiquitin gene of humans and Chinese hamsters.

The 5' upstream region of the Chinese hamster polyubiquitin gene CHUB2 was determined, and compared to that of the evolutionarily equivalent polyubiquitin gene UbC of humans. The 5' upstream region of the CHUB2 gene is distinct from that of the UbC gene in containing fewer recognition sequences for binding of transcription factors, which are quite sparsely distributed in this region. It seemed probable that the absence of AP-1 sites in the promoter of the CHUB2 gene was likely to be responsible for the very dissimilar regulation of the two genes by UV light and TPA, despite the fact that these genes are evolutionarily equivalent.

Animals↗
PubMed1996

Heterogeneous structure of the polyubiquitin gene UbC of HeLa S3 cells.

The nucleotide sequence of the polyubiquitin gene UbC of HeLa S3 cells and its upstream region was determined and characterized. Recognition sequences for the transcription factors HSF, NF kappa B, AP-1(c-jun), NF-IL6 and Sp1 were found in the upstream control region, a result consistent with the observation of a distinct regulatory response for the UbC gene compared with that of another polyubiquitin gene UbB. Employing a PCR procedure to amplify the entire coding region from genomic DNA, we found a heterogeneity in the repeat number (eight and nine repeats) of the ubiquitin coding units, which resulted from an apparent deletion of either the seventh or the eighth unit in the predominant nine-ubiquitin-unit coding gene. In addition, by comparison with the nucleotide sequence of the UbC gene of human leukocytes previously determined, we found a significant number of nucleotide discrepancies. However, these discrepancies could be substantially reduced by realigning the units so that the first and second ubiquitin units of the sequence determined here are translocated to the boundary between the eighth and the ninth units.

Base Sequence↗
PubMed1995

The human gene encoding the largest subunit of RNA polymerase II.

The nucleotide sequence of a large portion of the human RNA polymerase II large subunit (RpII LS)-encoding gene and its whole gene structure were determined. The RpIILS gene consists of 29 exons. The sequence of the 5' flanking region is highly conserved as compared with that of the mouse RpIILS and contains several SP1-binding sites, a CCAAT sequence and a sequence homologous to a heat-shock element. In addition, several inverted repeats and palindrome sequences were involved in the 5' upstream region. Those suggest that the 5' flanking domain of RpIILS would be highly structured which may be responsible for transcriptional regulation.

Amino Acid Sequence↗
PubMed1994

The methyl viologen-resistance-encoding gene smvA of Salmonella typhimurium.

The complete nucleotide sequence of the gene encoding the Salmonella typhimurium methyl viologen-resistant protein, SmvA, similar to QacA (resistance to quaternary ammonium ion) of Staphylococcus aureus, and the surrounding sequences were determined. This indicated that the gene arrangement of S. typhimurium is different from that of Escherichia coli in this region.

Cloning, Molecular↗
PubMed1994

Novel structure of a Chinese hamster polyubiquitin gene.

We isolated a polyubiquitin gene, CHUB2, from the V79 Chinese hamster genomic library, and determined its complete structure. Based on sequence homology to the human polyubiquitin gene UbC in the 5' and 3' untranslated region, the CHUB2 gene was characterized as the V79 Chinese hamster equivalent to the human UbC gene. However, the overall coding region structure of the CHUB2 gene was altered from the consensus structure of polyubiquitin genes, with the last ubiquitin coding unit being followed by 161 bp of partially deleted and mutated ubiquitin-like sequence. Although a similarly deleted and mutated polyubiquitin gene was recently reported in a partially sequenced cDNA of mouse (Finch et al. (1992) Cell Growth Differ. 3, 269-278), the present study describes the complete sequence of a polyubiquitin gene containing this unusual structure for the first time, and suggests that this structure is conserved in rodents. By employing both Southern and Northern analysis with a probe specific to the CHUB2 gene, it was found that a second, closely related gene is present in the Chinese hamster genome, and that both loci are transcriptionally active in V79 cells. The two genes, and their respective transcripts, differ in size because of variation in the relative number of repeating ubiquitin coding units.

Amino Acid Sequence↗
PubMed1994

Highly repetitive structure and its organization of the silk fibroin gene.

We have sequenced a number of cDNAs representing the Bombyx mori silk fibroin heavy chain transcript. These reveal that the central region of the fibroin gene is composed of alternate arrays of the crystalline element a and the noncrystalline element b. The core region is partitioned by a homogeneous nonrepetitive amorphous domain of around 100 bp in length. The element a is characterized by repeats of a highly conserved 18-bp sequence coding for perfect repeats of the unit peptide Gly-Ala-Gly-Ala-Gly-Ser. The element b is composed of repeats of a less-conserved 30-bp sequence which codes for a peptide similar to that in element a except in that (1) Ser is replaced by Tyr and (2) there are irregular substitutions of Ala to Val or Tyr. Therefore, the structure of the fibroin gene core consists of three-step higher-order periodicities. Heterogeneities in numbers of repeats are observed in each step of periodicity. Boundary sequence appeared in each periodicity to be quite homogeneous. Sequence analysis indicates that the unit sequences of elements a and b have homology to those of recombination hotspots reported in other genes and a recombination event may frequently occur between the misaligned sister chromatids, resulting in heterogeneities in repeat numbers and duplication or deletion of repetitive sequences. The repetitive superstructure of the fibroin gene may have been a result of continuous unequal crossovers in a primordial gene during evolution. A couple of important features of the fibroin protein were proved by the present nucleotide sequencing.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1994

Protein ubiquitination in the posterior silk glands of Bombyx mori.

Ubiquitin gene expression and the ubiquitination of proteins in the posterior silk glands (PSG) of B. mori were analyzed developmentally with respect to fibroin synthesis and degeneration. Two ubiquitin transcripts are expressed throughout larval stages, and the level of each transcript is regulated differently. The larger transcript, a polyubiquitin mRNA, was abundant during the molt stage, while levels of the smaller ubiquitin transcript increased immediately after molting. Only a single 65 kDa ubiquitinated protein was detected late in the 5th instar, and the amount increased up to spinning stage. This ubiquitinated protein may participate in the PSG degeneration.

Animals↗
PubMed1994

Relation of preference for location with scores on anxiety and on visibility in golf practice.

Previous research has indicated that seating preference in classrooms is related to some personal characteristics. Similar relations are assumed to be found in sports settings. In this study, the associations of rated preference for playing location in group practice of golf with trait anxiety and preference for visibility were investigated. Subjects were 165 Japanese university students who participated in a series of golf lessons. One-factor analyses of variance showed that subjects' rated preference for playing location was significantly related to their scores on trait anxiety and their preference for visibility of location. These results suggest that, in sports practice as in classrooms, preference for location may be associated with measures of personality and visibility.

Adult↗
PubMed1994

[Dual energy X-ray absorptiometry].

Dual energy X-ray absorptiometry (DXA) has been widely used in Japan. In this article, we described our lateral measurement of lumbar vertebral body, and reviewed the fracture threshold and the diagnosis of osteoporosis. The bone mineral density was measured in the anteroposterior projection (L2-4BMD) and in the lateral projection (L3 latBMD) by XR-26. The precisions (coefficient of variation) of lateral measurement in lateral decubitus position were 1.73% in BMC, 1.86% in BMD, and 0.82% in Area. The L31atBMD decreased at earlier age than L2-4BMD and showed a significant decrease between the 40s and the early 50s in healthy women as L2-4BMD. The lateral measurement of vertebral body was a very useful method to evaluate the early trabecular bone loss.

Absorptiometry, Photon↗
PubMed1993

The prognosis of idiopathic portal hypertension in Japan.

To clarify the factors relating to the prognosis of patients with idiopathic portal hypertension (IPH), we followed 171 patients with IPH until the end of 1990, who were registered in the database among those with abnormal portal circulation as of 1985 in hospitals of Japan. During the follow-up period, twenty patients died; 6 from gastro-intestinal tract bleeding, 5 from hepatic insufficiency and 9 from other causes. Cox's proportional hazard model suggested that male patients (hazard ratio 4.85, 95% confidence interval 1.82-12.94), with a disease onset at less than 40 years of age (H.R.3.94, 95% C.I. 1.31-11.57), and/or with varices (H.R.2.86, 95% C.I. 1.05-7.77) generally had poorer prognoses.

Adult↗
PubMed1993

[DNA fingerprint method of the cultured cells].

DNA fingerprint method is very available not only to examine the cross-contamination of cultured cell lines and their origins and but to know the somatic mutation frequency in the cultured cells by exposure of radiation and chemicals. The method for DNA fingerprint was grouped in the following four types in term of probe; multilocus minisatellite probe, simple sequence repeat probe, locus specific minisatellite probe and repeat unit sequence variation in minisatellites.

Cell Line↗