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Biomedical subjects

N Shima

Publications and source records attributed to N Shima.

At least 19 recordsLinked to original sources

Metabolism of the recently encountered designer drug, methylone, in humans and rats.

The urinary metabolites of methylone in humans and rats were investigated by analysing urine specimens from its abuser and after administrating to rats with gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-electrospray ionization mass spectrometry (LC-ESI MS), using authentic standards. The time-course excretion profiles of methylone and its three metabolites in rats were further investigated after a single intraperitoneal dosing of 5 mg kg-1 methylone hydrochloride. Two major metabolic pathways were revealed for both humans and rats as follows: (1) side-chain degradation by N-demethylation to the corresponding primary amine methylenedioxycathinone (MDC), partly conjugated; and (2) demethylenation followed by O-methylation of either a 3- or 4-OH group on the benzene ring to produce 4-hydroxy-3-methoxymethcathinone (HMMC) or 3-hydroxy-4-methoxymethcathinone (3-OH-4-MeO-MC), respectively, mostly conjugated. Of these metabolites, HMMC was the most abundant in humans and rats. The cumulative amount of urinary HMMC excreted within the first 48 h in rats was approximately 26% of the dose, and the amount of the parent methylone was not more than 3%. These results demonstrate that the analysis of HMMC will be indispensable for proof of the use of methylone in forensic urinalysis.

Adult↗

Isolation, identification and excretion profile of the principal urinary metabolite of the recently banned designer drug 1-(3-trifluoromethylphenyl)piperazine (TFMPP) in rats.

The metabolism of 1-(3-trifluoromethylphenyl)piperazine (TFMPP), a recently banned designer drug, in rats was studied by analysing its urinary metabolites. p-Hydroxy-TFMPP (p-OH-TFMPP) was isolated and identified as the main metabolite by using nuclear magnetic resonance spectroscopy, gas chromatography-mass spectrometry and high-performance liquid chromatography-electrospray ionization mass spectrometry (LC-ESI MS). The time-course excretion profiles of TFMPP and p-OH-TFMPP in rats were investigated following a single intraperitoneal dosing of 5 mg kg(-1) TFMPP by using an optimized analytical procedure that combined solid-phase extraction and LC-ESI MS techniques. The cumulative amount of p-OH-TFMPP excreted within the first 48 h reached approximately 64% of the dose, of which 70% was the glucuronide conjugated form. The cumulative amount of parent TFMPP excreted was less than 0.7% of the dose. The results suggest that p-OH-TFMPP would be the most relevant metabolite to be detected for TFMPP exposure in the forensic and clinical analysis of human urine.

Animals↗

Effect of dietary supplementation on the frequency of spontaneous lacZ mutations in the developing colon.

Epidemiological studies have demonstrated that dietary modifications can reduce the incidence of cancer. Specifically, diets high in vegetables and fruits are associated with lower rates of cancer at many sites. Somatic mutations have a critical role in carcinogenesis suggesting the use of in vivo mutation assays as an alternative approach to studying the relationship between diet and cancer. Since the rate of accumulation of spontaneous mutations is highest during growth and development early in life, we tested whether certain foods as dietary supplements could reduce the rate of mutation during this period using lacZ transgenic mice. Pregnant female mice were placed on a control diet or a diet supplemented to 20% final dry weight with broccoli, cabbage, carrots, flaxseed, green peas, green peppers, oranges or strawberries for the entire duration of their pregnancy and lactation. Mutation frequencies were subsequently measured at the lacZ transgene in colonic epithelial cells of the offspring at 3 weeks of age. A small number of measurements were also made on siblings at 8 weeks of age. While the control AIN-96G diet on its own resulted in lower mutant frequencies than had been observed in earlier experiments with lab chow, no significant reduction in mutant frequencies was detected for any of the foods tested as compared to the AIN-93G diet alone. Significantly more mutations were found at 3 weeks of age in mice fed diets supplemented with broccoli or oranges, but the result with oranges may be the result of jackpot mutations.

Animals↗

Desmutagenic and bio-antimutagenic activity of docosahexaenoic acid and eicosapentaenoic acid in cultured Chinese hamster V79 cells.

The antimutagenic activities of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) were examined by studying their effects on induction of 6-thioguanine (6TG)-resistant mutations by ethyl methanesulfonate (EMS) in cultured Chinese hamster V79 cells. DRA had a remarkable inhibitory effect against the cytotoxicity of EMS, when cells were simultaneously-treated with EMS, showing a blocking or scavenging activity of DHA in reduction of surviving fraction of cells. DHA had not so significant effect, when cells were treated before and after treatment with EMS. On the other hand, EPA had marked inhibiting effects against cytotoxicity of EMS, when cells were treated with EPA, before, simultaneous and after treatment with EMS. Against the induction of mutations by EMS, an antimutagenic activity of DHA was found when cells were pre-treated, simultaneously-treated or post-treated with DHA. EPA was also effective in reducing EMS-induced 6TG-resistant mutations when the cells were treated using the three different treatment procedures described above. The results suggest that in cultured Chinese hamster V79 cells, DHA and EPA may have both desmutagenic activity, which inactivates EMS chemically and/or enzymatically and bio-antimutagenic activity which suppresses mutation fixation after DNA is damaged by EMS.

Animals↗

Effect of intermittent hypoxia on cardiovascular adaptations and response to progressive hypoxia in humans.

The aim of the present study was to elucidate (1) the cardiovascular adaptations and response to hypoxic stimuli during short-term intermittent hypoxia and (2) whether the change in cardiovascular response to hypoxia is correlated to the change in hypoxic ventilatory chemosensitivity. Fourteen subjects were decompressed in a chamber to 432 torr, simulating an altitude of 4500 m, over a period of 30 min and were maintained at that pressure for 1 h daily for 7 days. Ventilatory (DeltaV(I)/DeltaSa(O2); Sa(O2) is arterial oxygen saturation), systolic and diastolic blood pressure (DeltaSBP/DeltaSa(O2) and DeltaDBP/DeltaSa(O2)), and heart rate (DeltaHR/DeltaSa(O2)) responses to progressive isocapnic hypoxia were measured before and after intermittent hypoxia. Resting ventilation, SBP, DBP, and HR did not change after intermittent hypoxia. DeltaSBP/DeltaSa(O2) and DeltaDBP/DeltaSa(O2) increased significantly after intermittent hypoxia accompanied by an enhanced DeltaV(I)/DeltaSa(C2), but there was no change in DeltaHR/DeltaSa(C2). There were significant correlations between the change in DeltaV(I)/DeltaSa(O2) and both the changes in DeltaSBP/DeltaSa(O2) and DeltaDBP/DeltaSa(O2) following intermittent hypoxic exposure. These results suggest that short-term intermittent hypoxia leads to the enhanced arterial BP response to hypoxic stimuli in humans, and that the enhanced peripheral chemosensitivity to hypoxia after intermittent hypoxia may play an important role in the increased arterial BP response.

Adaptation, Physiological↗

Intermittent hypoxia increases ventilation and Sa(O2) during hypoxic exercise and hypoxic chemosensitivity.

The purpose of this study was 1) to test the hypothesis that ventilation and arterial oxygen saturation (Sa(O2)) during acute hypoxia may increase during intermittent hypoxia and remain elevated for a week without hypoxic exposure and 2) to clarify whether the changes in ventilation and Sa(O2) during hypoxic exercise are correlated with the change in hypoxic chemosensitivity. Six subjects were exposed to a simulated altitude of 4,500 m altitude for 7 days (1 h/day). Oxygen uptake (VO2), expired minute ventilation (VE), and Sa(O2) were measured during maximal and submaximal exercise at 432 Torr before (Pre), after intermittent hypoxia (Post), and again after a week at sea level (De). Hypoxic ventilatory response (HVR) was also determined. At both Post and De, significant increases from Pre were found in HVR at rest and in ventilatory equivalent for O2 (VE/VO2) and Sa(O2) during submaximal exercise. There were significant correlations among the changes in HVR at rest and in VE/VO2 and Sa(O2) during hypoxic exercise during intermittent hypoxia. We conclude that 1 wk of daily exposure to 1 h of hypoxia significantly improved oxygenation in exercise during subsequent acute hypoxic exposures up to 1 wk after the conditioning, presumably caused by the enhanced hypoxic ventilatory chemosensitivity.

Adult↗

Transforming growth factor beta affects osteoclast differentiation via direct and indirect actions.

Transforming growth factor beta (TGF-beta) is abundant in bone and has complex effects on osteolysis, with both positive and negative effects on osteoclast differentiation, suggesting that it acts via more than one mechanism. Osteoclastogenesis is determined primarily by osteoblast (OB) expression of the tumor necrosis factor (TNF)-related molecule receptor activator of NF-kappaB ligand (RANKL) and its decoy receptor osteoprotegerin (OPG), which are increased and decreased, respectively, by osteolytic factors. A RANKL-independent osteoclastogenic mechanism mediated by TNF-alpha has also been shown. Therefore, we investigated TGF-beta effects on osteoclast formation in culture systems in which osteoclastogenic stimulus is dependent on OBs and culture systems where it was provided by exogenously added RANKL or TNF-alpha. Both OPG and TGF-beta inhibited osteoclast formation in hemopoietic cell/OB cocultures, but the kinetics of their action differed. TGF-beta also inhibited osteoclastogenesis in cocultures of cells derived from OPG null (opg-/-) mice. TGF-beta strongly decreased RANKL messenger RNA (mRNA) expression in cultured osteoblasts, and addition of exogenous RANKL to TGFbeta-inhibited cocultures of opg-/- cells partially restored osteoclastogenesis. Combined, these data indicate that the inhibitory actions of TGF-beta were mediated mainly by decreased OB production of RANKL. In contrast, in the absence of OBs, TGF-beta greatly increased osteoclast formation in recombinant RANKL- or TNF-alpha-stimulated cultures of hemopoietic cells or RAW 264.7 macrophage-like cells to levels several-fold greater than attainable by maximal stimulation by RANKL or TNF-alpha. These data suggest that TGF-beta may increase osteoclast formation via action on osteoclast precursors. Therefore, although RANKL (or TNF-alpha) is essential for osteoclast formation, factors such as TGF-beta may powerfully modify these osteoclastogenic stimuli. Such actions may be critical to the control of physiological and pathophysiological osteolysis.

Animals↗

Hepatocyte growth factor induces differentiation of adult rat bone marrow cells into a hepatocyte lineage in vitro.

Bone marrow (BM) cells originally include alpha-fetoprotein (AFP)- and c-Met [a receptor for hepatocyte growth factor (HGF)]-expressing cells. In vitro treatment of BM cells with HGF induced albumin-expressing hepatocyte-like cells. Furthermore, those hepatocyte-like cells expressed cytokeratins 8 and 18, which are typically expressed in normal adult hepatocytes. These findings demonstrate that BM cells include AFP-expressing hepatic progenitor cells that can be differentiated into hepatocytes by HGF in culture, indicating that such cultures are useful resources for cell transplantation therapy for liver diseases.

Animals↗

Dietary restriction during murine development provides protection against MNU-induced mutations.

The developmental stage is the most rapid period for the accumulation of somatic mutations. Epidemiological studies have also suggested a significant role of early life for cancer susceptibility, showing a protective effect of modest dietary restriction early in life. To determine if mutation rate, diet, and cancer risk are related, we have investigated the effect of dietary restriction on somatic mutations early in life. The diet of mouse dams was restricted during pregnancy and lactation by 10% from ad libitum control. F(1) pups (SWRxMutaMouse) were weaned at 3 weeks of age. Pups from dams that were on a restricted diet were kept under dietary restriction (40% until 5 weeks of age and then 20% until sacrifice). Only females from litters of seven or eight were used in this study. A portion of pups from both groups were treated with N-methyl-N-nitrosourea (MNU, 50mg/kg, i.p.) at 5 weeks of age and all mice were sacrificed at 10 weeks of age. The frequency of induced mutations was reduced by about 30% at the three loci studied, lacZ (P=0.028) and cII (P=0.042) and Dlb-1 (P=0.032) in the small intestine in the restricted group. A similar decrease in the lacZ mutant frequency was observed in the bone marrow, but the results did not reach statistical significance (P=0.074). Few differences in the lacZ mutant frequency were observed in the colon and the mammary epithelium, but variability of the mutant frequencies was such that an effect of similar magnitude could not be excluded statistically. Analysis of 47 cII mutants revealed that the majority of MNU-induced mutations were G:C to A:T transition at non-CpG sites, with no difference in the mutation spectrum between the two dietary groups.

Animals↗

Tumor necrosis factor alpha stimulates osteoclast differentiation by a mechanism independent of the ODF/RANKL-RANK interaction.

Osteoclast differentiation factor (ODF, also called RANKL/TRANCE/OPGL) stimulates the differentiation of osteoclast progenitors of the monocyte/macrophage lineage into osteoclasts in the presence of macrophage colony-stimulating factor (M-CSF, also called CSF-1). When mouse bone marrow cells were cultured with M-CSF, M-CSF-dependent bone marrow macrophages (M-BMM phi) appeared within 3 d. Tartrate-resistant acid phosphatase-positive osteoclasts were also formed when M-BMM phi were further cultured for 3 d with mouse tumor necrosis factor alpha (TNF-alpha) in the presence of M-CSF. Osteoclast formation induced by TNF-alpha was inhibited by the addition of respective antibodies against TNF receptor 1 (TNFR1) or TNFR2, but not by osteoclastogenesis inhibitory factor (OCIF, also called OPG, a decoy receptor of ODF/RANKL), nor the Fab fragment of anti-RANK (ODF/RANKL receptor) antibody. Experiments using M-BMM phi prepared from TNFR1- or TNFR2-deficient mice showed that both TNFR1- and TNFR2-induced signals were important for osteoclast formation induced by TNF-alpha. Osteoclasts induced by TNF-alpha formed resorption pits on dentine slices only in the presence of IL-1alpha. These results demonstrate that TNF-alpha stimulates osteoclast differentiation in the presence of M-CSF through a mechanism independent of the ODF/RANKL-RANK system. TNF-alpha together with IL-1alpha may play an important role in bone resorption of inflammatory bone diseases.

Acid Phosphatase↗

Cardiovascular response to hypoxia after endurance training at altitude and sea level and after detraining.

The purpose of this study was to elucidate 1) the effects of endurance exercise training during hypoxia or normoxia and of detraining on ventilatory and cardiovascular responses to progressive isocapnic hypoxia and 2) whether the change in the cardiovascular response to hypoxia is correlated to changes in the hypoxic ventilatory response (HVR) after training and detraining. Seven men (altitude group) performed endurance training using a cycle ergometer in a hypobaric chamber of simulated 4,500 m, whereas the other seven men (sea-level group) trained at sea level (K. Katayama, Y. Sato, Y. Morotome, N. Shima, K. Ishida, S. Mori, and M. Miyamura. J. Appl. Physiol. 86: 1805-1811, 1999). The HVR, systolic and diastolic blood pressure responses (DeltaSBP/DeltaSa(O(2)), DeltaDBP/DeltaSa(O(2))), and heart rate response (DeltaHR/DeltaSa(O(2)); Sa(O(2)) is arterial oxygen saturation) to progressive isocapnic hypoxia were measured before and after training and during detraining. DeltaSBP/DeltaSa(O(2)) increased significantly in the altitude group and decreased significantly in the sea-level group after training. The changed DeltaSBP/DeltaSa(O(2)) in both groups was restored during 2 wk of detraining, as were the changes in HVR, whereas there were no changes in the DeltaDBP/DeltaSa(O(2)) and DeltaHR/DeltaSa(O(2)) throughout the experimental period. The changes in DeltaSBP/DeltaSa(O(2)) after training and detraining were significantly correlated with those in HVR. These results suggest that DeltaSBP/DeltaSa(O(2)) to progressive isocapnic hypoxia is variable after endurance training during hypoxia and normoxia and after detraining, as is HVR, but DeltaDBP/DeltaSa(O(2)) and DeltaHR/DeltaSa(O(2)) are not. It also suggests that there is an interaction between the changes in DeltaSBP/DeltaSa(O(2)) and HVR after endurance training or detraining.

Altitude↗

Somatic mutation in the mammary gland: influence of time and estrus.

A critical factor in the quantitation of mutation induction in vivo is the time interval between treatment and sampling. In order to study mutagenesis in the mammary epithelium, the cell type in which breast cancer arises, we have measured the manifestation time, the minimum time required for the maximum mutant frequency to be achieved, in this tissue. The F1 LacZ transgenic mice (Muta MousexSWR) were treated with N-ethyl-N-nitrosourea (ENU) at 50 mg/kg for five consecutive days and then sampled at 1, 2, 4, 6, 9, or 12 weeks after the last treatment. The LacZ- mutant frequency reached a maximum at 4 weeks post-treatment and did not vary significantly thereafter. Dlb-1- mutations in the small intestine reached a maximum at 2 weeks after treatment and did not vary significantly thereafter. Since the stage of estrus cycle during carcinogen exposure influences the mammary tumor incidence and latency, it was expected that it would also affect mutation induction. To test this, F1 LacZ mice in the estrus or di-estrus stage were treated with an acute dose of 250 mg/kg ENU and sampled 10-13 weeks post-treatment. No statistical difference between the two groups was found, indicating that the effect of estrus on carcinogenesis is not due to variation in the sensitivity of the stage of the mammary gland to mutation.

Animals↗

Cloning and characterization of the gene encoding mouse osteoclast differentiation factor.

Osteoclast differentiation factor (ODF), a ligand for osteoclastogenesis inhibitory factor (OCIF)/ osteoprotegerin (OPG), is a member of the membrane-associated tumor necrosis factor (TNF) family and induces osteoclast-like cell formation in vitro. In the present study, mouse ODF genomic clones were isolated and sequenced to determine their gene structure. The mouse ODF gene is a single copy gene consisting of five exons and spans approximately 40kb of the mouse genome. The first exon encodes the intracellular and transmembrane domains. The extracellular region of ODF containing the TNF homologous domain is encoded by exons 1 through 5. The translation-termination codon and six polyadenylation signal residues are present in exon 5. A major transcription-initiation site is present 143 nucleotides upstream of the initiation-ATG codon. This genomic organization is similar to that of other members of the TNF family, especially the CD40 ligand.

Animals↗

Basic fibroblast growth factor induces osteoclast formation by reciprocally regulating the production of osteoclast differentiation factor and osteoclastogenesis inhibitory factor in mouse osteoblastic cells.

Basic fibroblast growth factor (bFGF) induced osteoclast formation in co-cultures of mouse spleen cells and osteoblasts. Osteoclastogenesis inhibitory factor (OCIF) and a selective cyclooxygenase-2 (COX-2) inhibitor, NS-398, abolished bFGF-induced osteoclast formation. bFGF did not affect spleen cells, but it did affect osteoblasts, to stimulate osteoclast formation. Northern blot analysis revealed that bFGF up-regulated the expression of osteoclast differentiation factor (ODF) and COX-2 and down-regulated the expression of OCIF in primary osteoblastic cells. NS-398 abolished the increase of ODF mRNA, but it had no effect on the decrease of OCIF mRNA. NS-398 suppressed the binding of (125)I-labeled OCIF to osteoblastic cells treated with bFGF. Enzyme-linked immunosorbent assay showed that bFGF inhibited OCIF production by osteoblastic cells, and the inhibition was not affected by NS-398. We conclude that bFGF induces osteoclast formation by stimulating ODF production through COX-2-mediated prostaglandin synthesis and by suppressing OCIF production through a mechanism independent of prostaglandin synthesis.

Animals↗

Basic fibroblast growth factor inhibits osteoclast formation induced by 1alpha,25-dihydroxyvitamin D(3) through suppressing the production of osteoclast differentiation factor.

Basic fibroblast growth factor (bFGF) inhibited osteoclast-like cell (OCL) formation in cocultures of mouse spleen cells with either osteoblasts or a stromal cell line, ST2, in the presence of 1alpha, 25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)]. bFGF directly acted on osteoblasts/stromal cells, but not osteoclast progenitors, to inhibit 1,25(OH)(2)D(3)-induced OCL formation. bFGF suppressed the mRNA expression of osteoclast differentiation factor (ODF) but did not affect that of osteoclastogenesis inhibitory factor (OCIF) in ST2 cells treated with 1,25(OH)(2)D(3) and dexamethasone. Enzyme-linked immunosorbent assay showed that bFGF hardly affected OCIF production in the treated ST2 cells. A genetically engineered soluble form of ODF, but not anti-OCIF neutralizing antibody, abolished bFGF-mediated inhibition of OCL formation. bFGF suppressed the binding of (125)I-labeled OCIF to both ST2 cells and osteoblasts treated with 1,25(OH)(2)D(3). These findings indicate that bFGF inhibits 1,25(OH)(2)D(3)-induced OCL formation via suppression of ODF production by osteoblasts/stromal cells.

Animals↗

A novel molecular mechanism modulating osteoclast differentiation and function.

Osteoclasts, the multinucleated giant cells that resorb bone, develop from hematopoietic cells of the monocyte/ macrophage lineage. Osteoblasts, as well as bone marrow stromal cells, support osteoclast development through a mechanism of cell-to-cell interaction with osteoclast progenitors. We recently purified and molecularly cloned osteoclastogenesis inhibitory factor (OCIF), which was identical to osteoprotegerin (OPG). OPG/OCIF, a secreted member of the tumor necrosis factor (TNF) receptor family, inhibited differentiation and activation of osteoclasts. A single class of high-affinity binding sites for OPG/OCIF appeared on a mouse bone marrow stromal cell line, ST2, in response to 1alpha,25-dihydroxyvitamin D3 [1,25(OH)2D3] and dexamethasone (Dex). When the binding sites were occupied by OPG/OCIF, ST2 cells failed to support the osteoclast formation from spleen cells. To identify an OPG/OCIF ligand, we screened a cDNA expression library of ST2 cells treated with 1,25(OH)2D3 and Dex using OPG/OCIF as a probe. The cloned molecule was found to be a member of the membrane-associated TNF ligand family, and it induced osteoclast formation from mouse and human osteoclast progenitors in the presence of macrophage colony-stimulating factor (M-CSF) in vitro. Expression of its gene in osteoblasts/stromal cells was up-regulated by osteotropic factors, such as 1,25(OH)2D3, prostaglandin E2 (P(GE2), parathyroid hormone (PTH), and interleukin (IL)-11. A polyclonal antibody against this protein, as well as OPG/OCIF, negated not only the osteoclastogenesis induced by the protein, but also bone resorption elicited by various osteotropic factors in a fetal mouse long bone culture system. These findings led us to conclude that the protein is osteoclast differentiation factor (ODF), a long sought-after ligand that mediates an essential signal to osteoclast progenitors for their differentiation into active osteoclasts. Recent analyses of ODF receptor demonstrated that RANK, a member of the TNF receptor family, is the signaling receptor for ODF in osteoclastogenesis, and that OPG/OCIF acts as a decoy receptor for ODF to compete against RANK. The discovery of ODF, OPG/OCIF, and RANK opens a new era in the investigation of the regulation of osteoclast differentiation and function.

Animals↗

A randomized outcome evaluation of group exercise programs in long-term care institutions.

BACKGROUND: Physical activity programs in nursing homes typically consist of seated, range of motion (ROM) exercises, regardless of resident abilities. The Functional Fitness for Long-Term Care (FFLTC) Program was designed not only to maintain ROM, but also to improve strength, balance, flexibility, mobility, and function. In addition, it was tailored to meet the needs of both high and low mobility residents. METHODS: The feasibility and efficacy of the FFLTC Program were evaluated with 68 residents (mean age 80) from five institutions. Persons were classified as low or high mobility and randomized into either the FFLTC program or a seated ROM program. Classes were conducted in groups of 4 to 10 residents by trained facility staff for 45 minutes, three times per week. Assessments at baseline and 4 months consisted of mobility, balance, gait, flexibility, functional capacity, and several upper and lower extremity strength measures. RESULTS: Attendance averaged 86% for the FFLTC and 79% for the ROM classes. Four months of exercise led to significant improvements in mobility (16%), balance (9%), flexibility (36%), knee (55%), and hip (12%) strength for the FFLTC group. Shoulder strength was the only improvement found for the ROM group. The ROM group significantly deteriorated in some areas, particularly hip strength, mobility, and functional ability. CONCLUSIONS: Institutionalized seniors, even those who are physically frail, incontinent and/or have mild dementia, can respond positively to a challenging exercise program. The FFLTC program demonstrated clear benefits over typical, seated ROM exercises. Moreover, with minimal training, the program can be safely delivered at low cost by institutional staff and volunteers.

Activities of Daily Living↗