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Biomedical subjects

R Itoh

Publications and source records attributed to R Itoh.

At least 145 records · Page 8Linked to original sources
PubMed1996

A possible change in doubling time of haemopoietic progenitor cells with stem cell development.

We separated haemopoietic progenitors derived from marrow cells of 5-fluorouracil (5-FU)-treated mice into three groups, based on the stages of stem cell development and studied doubling time, using a serum-free clonal culture system. Stage I progenitors were those present in primary marrow cells from 5-FU-treated mice. Stages II and III progenitors were early and late progenies in culture of stage I progenitors respectively. The morphological analysis of colonies derived from stage I, II and III progenitors demonstrated an association of progression of stages with loss of multipotentiality. The doubling time of haemopoietic progenitors was estimated by sequential analysis of colony formation and studies of growth fraction. The time required for haemopoietic progenitors to double shortened as their stage of development progressed. Alteration in one doubling time of haemopoietic progenitors at progressive stages of stem cell development was seen in cultures supported by various combinations of growth factors, including interleukin-3 (IL-3), IL-11. and steel factor (SF), Cell-cycle analysis suggested that reduction of the doubling time of haemopoietic progenitors is probably due to a decrease in the time spent in the G1 phase of the cell cycle. Our results suggest that in early haemopoiesis the doubling time of haemopoietic progenitors may change with stem cell development.

Animals↗
PubMed1996

Activity of the ligand for c-mpl, thrombopoietin, in early haemopoiesis.

We examined the role of the ligand for c-mpl. thrombopoietin (TPO). in murine early haemopoiesis. using a serum-free culture system. TPO in combination with the ligand for c-kit (SF) or interleukin-3 (IL-3) supported colony formation by marrow cells of 5-fluorouracil (5-FU)-treated mice whereas TPO alone yielded no colony. When blast cell colonies grown in the presence of TPO plus SF or TPO plus IL-3 were individually replated in suspension cultures containing serum and several growth factors, various combinations of myeloid lineages were seen, indicating that the progenitors supported by TPO plus SF or TPO plus IL-3 are multipotential. Delayed addition experiments demonstrated that TPO has the potential to effectively support the survival of haemopoietic progenitors. We then studied the effects of TPO on proliferative kinetics of cycling progenitors. TPO hastened IL-3-dependent growth of progenitors by shortening the time required for cell cycling. These results suggest that TPO as a single factor, can support the survival of haemopoietic progenitors and TPO synergizes with SF or IL-3 to act on early multipotential haemopoietic progenitors.

Animals↗
PubMed1996

Sodium excretion in relation to calcium and hydroxyproline excretion in a healthy Japanese population.

To evaluate whether habitual excess sodium intake is a significant risk factor for calcium loss, we studied the relation between calcium excretion and sodium excretion in 410 male and 476 female Japanese aged 20-79 y. They were apparently healthy, free-living, and consuming diets of their own choosing. We divided the subjects into two groups: 20-49 y olds and 50-79 y olds. In each group, we observed significant positive correlation between daily calcium excretion and daily sodium excretion in both sexes. Multivariate analyses revealed that in each age group the relation was still significant after sex, age, body weight, and protein, calcium, and phosphorus intakes were adjusted for. The increases in urinary calcium excretion were estimated to be approximately 0.6 and 1.0 mmol for a 100-mmol increment in urinary sodium excretion for the 20-49 y olds and 50-79-y olds, respectively. We also observed significant positive correlations between daily hydroxyproline excretion and daily sodium excretion in both sexes for both age groups. The relation was still significant after sex, age, body weight, and protein intake from meat and fish were adjusted for. The results suggest that individuals with high sodium intake may lose more calcium in their urine than those with low sodium intake.

Adult↗
PubMed1996

Lumbosacral nerve root enhancement with disk herniation on contrast-enhanced MR.

PURPOSE: To evaluate the clinical importance of nerve root enhancement associated with lumbar disk herniation. METHODS: Thirty-two patients with lumbar disk herniation were examined with unenhanced and contrast-enhanced MR imaging. We investigated the relationship between nerve root enhancement and location of herniated disk in the epidural space, onset pattern of symptoms, subsequent treatment, and surgical findings. RESULTS: Ten of the 32 patients had nerve root enhancement, and all belonged to the group with abrupt and severe nerve root compression with no residual space for the root between the herniated disk and the pedicle in the lateral recess. Tight compression of the root without mobility was seen in the four patients with nerve root enhancement who were treated surgically. CONCLUSION: Nerve root enhancement may indicate the existence of abrupt and severe compression of the nerve root as well as the presence of severe adhesion of the herniated disk and the nerve root. This finding does not necessarily determine the type of subsequent treatment.

Adolescent↗
PubMed1996

Aphidicolin uncouples the chloroplast division cycle from the mitotic cycle in the unicellular red alga Cyanidioschyzon merolae.

The unicellular red alga Cyanidioschyzon merolae possesses one chloroplast, one mitochondrion, and one cell nucleus. Since the division of these organelles and cytokinesis occur in a coordinated manner, mitosis and the organelle division cycles must be tightly coupled. We report here that aphidicolin, a specific inhibitor of DNA polymerase alpha, uncouples the chloroplast division cycle from the mitotic cycle. The effects of aphidicolin on C. merolae cells were examined by both epifluorescence and electron microscopy. When cells at the S phase in synchronous culture were treated with aphidicolin, mitosis and cytokinesis did not occur, while chloroplast division did. Moreover, both of the chloroplasts in these cells continued to divide and then generated four or more chloroplasts per cell. The inhibition of cell-nuclear DNA synthesis by aphidicolin was confirmed using microfluorometry. In addition, microfluorometry revealed that the total size and the amount of DNA in chloroplasts in aphidicolin-treated cells remained constant during uncoupled chloroplast division. As a result, the size and amount of DNA per chloroplast decreased stepwise during chloroplast division. Electron microscopic examination of aphidicolin-treated cells showed that the second division of chloroplasts uses a chloroplast-dividing ring similar to that in cells undergoing normal chloroplast division. These results suggest that chloroplast division by the dividing ring is free from a checkpoint control that inhibits the progression of mitosis and cytokinesis in the absence of the completion of cell-nuclear DNA synthesis, and also that chloroplasts lack a checkpoint control mechanism that inhibits its division without growth or DNA synthesis of itself.

Aphidicolin↗
PubMed1995

Accelerated cell-cycling of hematopoietic progenitor cells by growth factors.

Recent advances in molecular biology have led to the identification of hematopoietic growth factors that support and influence the proliferation of hematopoietic progenitor cells in vitro and in vivo. Although these factors have been extensively studied, little is known of their role in the regulation of cell-cycling of hematopoietic progenitors, especially in the early stage of hematopoiesis. In the present study, we examined the effects of early acting growth factors on proliferative kinetics of hematopoietic progenitors by monitoring the number of cells in individual developing colonies, using an in vitro clonal assay. Interleukin-11 (IL-11) or steel factor (SF), alone or in combination, shortened the time for the size of IL-3-dependent colonies to double. Consecutive replating experiments provided evidence for direct action of growth factors on the growth rate of hematopoietic progenitor cells. Shortening of the time for the total cell number in the colonies to double was due to a reduction in time for each single cell within the respective colonies to become two daughter cells, and there was no alteration in the incidence of cells with a proliferative capacity. Cell-cycle analysis demonstrated that IL-11 has the potential to induce a shortened time for cell-cycle of hematopoietic progenitor cells without affecting distribution of each fraction of the cell-cycle, whereas SF has the potential to reduce cell-cycle time mainly by decreasing the time required for hematopoietic progenitor cells to go through the G1 phase. These results suggest that growth factors may modulate cell-cycling of hematopoietic progenitor cells.

Animals↗
PubMed1995

Specific detection of Campylobacter jejuni by means of polymerase chain reaction in chicken litter.

A routine detection assay of Campylobacter jejuni was developed with the polymerase chain reaction (PCR). A pair of oligonucleotide primers from the flaA of C. jejuni were used in detection by PCR. Although the primer pair specifically detected C. jejuni strains, they did not detect strains of C. coli, C. fetus, Salmonella spp. or Escherichia coli. In litter inoculated with C. jejuni, specific detection of C. jejuni was obtained by PCR with this primer pair.

Animals↗
PubMed1995

Sociodemographic factors and life-styles affecting micronutrient status in an apparently healthy elderly Japanese population.

To define the effects of sociodemographic factors and life-styles on intakes and biochemical measures of iron, thiamine, riboflavin and ascorbic acid in healthy elderly Japanese, a survey was conducted on 190 subjects aged 65 to 80 years. Results of multivariate analyses of the data indicated that, independent of the other factors, smoking was significantly and negatively associated with ascorbic acid status and its intake (expressed as its concentration per unit of energy in diets). After controlling for the other factors, participation in a nutrition education program in the past was significantly and positively associated with intakes of thiamine, riboflavin and ascorbic acid. Biochemical measures of these three vitamins were also significantly better in the participants.

Aged↗
PubMed1995

Cytokinesis by a contractile ring in the primitive red alga Cyanidium caldarium RK-1.

To better understand the mechanism of cytokinesis in eukaryotes, the behavior of the contractile ring in the two unicellular primitive red algae Cyanidioschyzon merolae and Cyanidium caldarium RK-1, which have the smallest genome size among eukaryotes, was examined by fluorescein isothiocyanate (FITC)-phalloidin fluorescence microscopy, fluorometry using a video-intensified microscope photoncounting system, transmission electron microscopy and immunoblotting techniques. Cells in each alga contained one nucleus, one mitochondrion and one chloroplast, which were aligned in that order. During cytokinesis in C. merolae, a contractile ring was not observed by fluorescence microscopy or by transmission electron microscopy. In contrast, in C. caldarium RK-1, a contractile ring appeared at the equatorial region of the dividing cells and began to contract from the side of the chloroplast. During contraction of this ring, the total fluorescent intensities due to FITC-phalloidin remained constant. Electron microscopy revealed outer and inner bands approximately 80 nm wide and 9 nm thick which ran parallel to each other just beneath the cell membrane. These bands were visible at the equator of the cell just before the initiation of cytokinesis and constricted from the pole of the chloroplast. Both bands increased in width as cleavage progressed. The inner ring consisted of a bundle of approximately 20 actin-like filaments which were arranged as a raft. In the outer ring, such fine filaments were not visible. It seems likely that the bundle of filaments, known as the contractile ring, is composed of two different elements: an inner band of actin filaments and an outer band of unknown materials.(ABSTRACT TRUNCATED AT 250 WORDS)

Actin Cytoskeleton↗
PubMed1995

[Treatment of recurrent uterine endometrial cancer in adjuvant therapy with medroxyprogesterone acetate (MPA) in addition of etoposide].

In recent years, we treated recurrent uterine endometrial cancer by combined therapy including CDDP. But in poor cases, like renal failure and such, it is difficult to perform the therapy. Two cases of recurrent uterine endometrial cancer treated earlier with MPA were presently treated with an addition of etoposide. The first case was given etoposide (50 mg/m2/day 4 times for 21 days by oral administration). The target tumor mass was reduced in size, occult blood vanished, and the tumor marker was reduced. The other case was treated with etoposide, 50 mg/body/day for 21 days by oral administration, but because of diarrhea, the dose had to be decreased to 25 mg/body/day every day. The tumor marker was reduced and genital bleeding vanished. These cases suggested that etoposide-MPA combined therapy might be effective for recurrent uterine endometrial cancer of well-differentiated type.

Adenocarcinoma↗
PubMed1994

Sequence homology of Chinese hamster metallothionein genes I and II to those of the mouse and rat, and their amplification in Cd-resistant cells.

The metallothionein (MT) I and II genes were isolated from Chinese hamster cells and sequenced. The MT-II gene is located about 6 kb upstream of the MT-I gene and their arrangement is similar to those of the mouse and rat MT genes. The sequence of the Chinese hamster MT-I gene is highly homologous to those of the mouse and rat, particularly in their promoter regions of MT-I. However, the promoter region of MT-II has less homology with those of the mouse and rat due t to insertions and deletions. The MT-I and MT-II genes were equally amplified 4-8-times in the Cd-resistant Chinese hamster cells, suggesting that both genes are included in the same amplification unit. Cytogenetic analysis of Cd-resistant cells by in situ hybridization showed that they are randomly integrated into multiple sites on the chromosomes.

Amino Acid Sequence↗
PubMed1994

Involvement of DNA polymerase delta and/or epsilon in joining UV-induced DNA single strand breaks in human fibroblasts (comparison of effects of butylphenyldeoxyguanosine with aphidicolin).

DNA polymerases involved in ultraviolet (UV)-induced DNA repair were studied in human fibroblasts using the inhibitors of DNA polymerases, aphidicolin which inhibits DNA polymerases alpha, delta and epsilon, and butylphenyldeoxyguanosine (BuPGdR) which inhibits DNA polymerase alpha strongly and weakly inhibits delta and epsilon. Both inhibitors inhibited replicative DNA synthesis in a dose dependent manner as measured by thymidine incorporation. However, BuPGdR did not accumulate single strand breaks in cells irradiated with 5 J/m2 UV-light even at the highest dosage tested, indicating that BuPGdR does not inhibit DNA repair. On the other hand, aphidicolin accumulated single strand breaks in UV-light irradiated cells. These results suggest that DNA polymerase delta and/or epsilon are mainly involved in UV-induced DNA repair.

Aphidicolin↗
PubMed1994

Purification and some properties of an IMP-specific 5'-nucleotidase from yeast.

An IMP-hydrolysing enzyme was purified to homogeneity from yeast extract. It was a soluble protein with an apparent molecular mass of 220 kDa, with a subunit molecular mass of 55 kDa. It was highly specific for IMP, and there was virtually no detectable activity with the other purine and pyrimidine nucleotides tested, including AMP and dIMP. The enzyme had a pH optimum of 6.0-6.5. Its activity was absolutely dependent on bivalent metal salts: Mg2+ was most potent, followed by Co2+ and Mn2+. The velocity/substrate-concentration plot of the enzyme was slightly sigmoidal (h = 1.7) and the s0.5 was 0.4 mM. ATP stimulated the enzyme by decreasing both h and s0.5. Diadenosine tetraphosphate stimulated the enzyme as effectively as ATP. Although the properties of the enzyme are similar to those of the IMP/GMP 5'-nucleotidase identified in various animals [Itoh (1993) Comp. Biochem. Physiol. 105B, 13-19], the substrate specificity of the former was much more strict than the latter.

5'-Nucleotidase↗
PubMed1994

Interleukin 8 in Behçet's disease.

Activated peripheral polymorphonuclear leukocytes (PMNs) and infiltration of PMNs into the lesions are characteristic findings of Behçet's disease (BD). A variety of cytokines, including interleukin 8 (IL-8), have been shown to activate PMNs. To investigate the role of IL-8 in the development of BD lesions, IL-8 production in vivo and in vitro was examined in 25 BD patients. IL-8 levels measured by ELISA in the non stimulated culture supernatants of peripheral mononuclear cells (MNCs) were higher in patients with active BD than in those with inactive BD or normal controls. Without LPS stimulation, IL-8 mRNA expression in incubated MNCs detected by Northern blot analysis was higher in active BD patients than in controls. Polarization assay confirmed the accelerated activity of PMN isolated from patients with active BD. However, these PMNs did not respond to IL-8 as strongly as to FMLP (an exogenous stimulator); a possible reason is that the PMNs of these patients are constantly exposed to IL-8 in vivo. Immunohistochemically, MNCs, endothelial cells and fibroblasts in BD lesions were positively stained by anti-IL-8 antibody. These data indicate that the production of IL-8 may be accelerated in inactive BD and that IL-8 may play an important role in the pathogenesis of BD.

Adult↗
PubMed1994

Pathogenesis of mucocutaneous lesions in Behçet's disease.

Behçet's disease (BD) is characterized by recurrent oral aphthae, skin lesions, eye lesions, and genital ulceration. To determine the pathogenesis of BD, we performed histological and immunohistochemical studies of these mucocutaneous lesions, an assay of neutrophil activity, and HLA typing. Dense dermal or subcutaneous infiltrations of polymorphonuclear cells (PMN) without leukocytoclastic vasculitis were found in 28 of 57 lesions. Immunohistochemically, deposits of C3 on the vessels were found in 12 of 31 lesions. Deposits of immunoglobulin were not found except for one of IgM. C3 deposits and PMN infiltrations were significantly related (p < 0.05). PMN activity by polarization was enhanced; however, the results did not show a significant relationship with the PMN infiltrations or the C3 deposits. The incidence of HLA-B51 was significantly high in BD, but no significant relationship was found between HLA-B51 and the results of other examinations. These results suggest that the pathogenesis of BD lesions differs from that of collagen diseases and that C3 deposits on the vessels may play an important role in the development of mucocutaneous lesions where PMN have mainly infiltrated.

Adolescent↗
PubMed1994

Granulocyte colony-stimulating factor (G-CSF) and granulocyte macrophage colony-stimulating factor (GM-CSF) in Behçet's disease.

Increases in the number and activity of peripheral polymorphonuclear neutrophils (PMNs) is often found in Behçet's disease (BD), indicating that PMN may play an important role in the pathogenesis of this disorder. It has recently been reported that G-CSF and GM-CSF, a family of hematopoietic growth factors, enhance PMN activity. To explore the role of these two CSFs in BD, we first examined the chemotactic response of PMNs to these CSFs by performing a polarization assay. PMN response to G-CSF in BD patients was lower than that in controls, while PMN response to GM-CSF was similar in patients and controls. However, PMNs from BD patients showed an enhanced chemotactic response to N-formyl-L-methionyl-leucyl-phenylalanine. Thus, it is speculated that the PMNs of the patients might have already been activated in vivo by G-CSF and thus could not respond further to this agent in vitro. We examined G-CSF and GM-CSF mRNA expressions in peripheral mononuclear cells stimulated with LPS, PMA, and Con A by Northern hybridization. G-CSF mRNA expression levels in BD patients were higher than in the controls, while GM-CSF mRNA expression levels were lower than in the controls. We also examined the serum levels of the two CSFs by ELISA and EIA. However, all levels of the two CSFs in both patients and controls were not detectable, except in the case of one BD patient in the active stage of the disease, who showed high levels of G-CSF, but not of GM-CSF.(ABSTRACT TRUNCATED AT 250 WORDS)

Behcet Syndrome↗