Acute dietary nitrate supplementation does not change venous volume and compliance in healthy young adults.

In this crossover study, we investigated the influence of inorganic nitrate ([Formula: see text]) supplementation on venous volume and compliance in the resting forearm and calf. Twenty healthy young adults were assigned to receive an [Formula: see text]-rich beverage [beetroot juice (BRJ): 140 mL; ∼8 mmol [Formula: see text]] or an [Formula: see text]-depleted control beverage [prune juice (CON): 166 mL; < 0.01 mmol [Formula: see text]). Two hours after consuming the allocated beverage, each participant rested in the supine position for 20 min. Cuffs were then placed around the right upper arm and right thigh, inflated to 60 mmHg for 8 min, and then decreased to 0 mmHg at a rate of 1 mmHg/s. During inflation and deflation of cuff pressure, changes in venous volume in the forearm and calf were measured by venous occlusion plethysmography. Venous compliance was calculated as the numerical derivative of the cuff pressure-venous volume curve in the limbs. The plasma [Formula: see text] concentration was elevated by intake of BRJ (before, 15.5 ± 5.8 µM; after, 572.0 ± 116.1 µM, P < 0.05) but not by CON (before, 14.8 ± 7.2 µM; after, 15.3 ± 7.4 µM, P > 0.05). On the other hand, there was no significant difference in venous volume or compliance in the forearm or calf between BRJ and CON. These findings suggest that although acute inorganic NO3- supplementation may enhance the activity of nitric oxide (NO) via nitrite → NO pathway, it does not influence venous volume or compliance in the limbs in healthy young adults.

A Redox-Silent Analogue of Tocotrienol May Break the Homeostasis of Proteasomes in Human Malignant Mesothelioma Cells by Inhibiting STAT3 and NRF1.

6-O-Carboxypropyl-alpha-tocotrienol (α-T3E) is a multi-target redox-silent analogue of tocotrienol that exhibits cytotoxicity against many cancer cells, including malignant mesothelioma (MM) cells. α-T3E has several molecular targets to effectively induce cytotoxicity against MM cells; however, the mechanisms underlying this cytotoxicity remain unclear. In the present study, we demonstrated that the α-T3E-dependent disruption of the homeostasis of proteasomes strongly induced endoplasmic reticulum (ER) stress, which resulted in effective cytotoxicity against MM cells. The α-T3E-dependent disruption of the homeostasis of proteasomes depended on decreases in proteasome subunits via the inactivation of signal transducer and activator of transcription 3 (STAT3) and nuclear factor erythroid 2 related factor-1 (NRF1), which inhibited protease activity, such as chymotrypsin-like activity, in proteasomes. The α-T3E-dependent inhibition of this activity also induced severe ER stress and ultimately resulted in effective cytotoxicity against MM cells with chemoresistance. The present results indicate that α-T3E acts as an effective anti-mesothelioma agent by disrupting the homeostasis of proteasomes through the simultaneous inactivation of STAT3 and NRF1.

Effect of Acute Dietary Nitrate Supplementation on the Changes in Calf Venous Volume during Postural Change and Skeletal Muscle Pump Activity in Healthy Young Adults.

Dietary nitrate (NO3-) supplementation is known to enhance nitric oxide (NO) activity and acts as a vasodilator. In this randomized crossover study, we investigated the effect of inorganic NO3- supplementation on the changes in calf venous volume during postural change and subsequent skeletal muscle pump activity. Fifteen healthy young adults were assigned to receive beetroot juice (BRJ) or a NO3--depleted control beverage (prune juice: CON). Two hours after beverage consumption, the changes in the right calf volume during postural change from supine to upright and a subsequent right tiptoe maneuver were measured using venous occlusion plethysmography. The increase in calf volume from the supine to upright position (total venous volume [VV]) and the decrease in calf volume during the right tiptoe maneuver (venous ejection volume [Ve]) were calculated. Plasma NO3- concentration was higher in the BRJ group than in the CON group 2 h after beverage intake (p < 0.05). However, VV and Ve did not differ between CON and BRJ. These results suggest that acute intake of BRJ may enhance NO activity via the NO3- → nitrite → NO pathway but does not change calf venous pooling due to a postural change or the calf venous return due to skeletal muscle pump activity in healthy young adults.

Changes in homocysteine and non-mercaptoalbumin levels after acute exercise: a crossover study.

BACKGROUND: Acute exercise is one factor that increases blood homocysteine levels, and elevated homocysteine levels cause oxidative stress. Albumin, which is abundant in blood, is an antioxidant, and the redox state of albumin is used as an index of oxidative stress in blood. This study aimed to assess the effect of acute exercise on plasma homocysteine levels and the blood non-mercaptoalbumin/mercaptoalbumin ratio as an oxidative stress marker. METHODS: This study used a crossover design with exercise and control conditions. Under exercise conditions, a bicycle ergometer was used to perform 40 min of transient constant-load exercise at 65% heart rate reserve. Under control conditions, participants rested for 40 min. Blood was collected before, 30 min after, and 90 min after exercise, and at the same time points under control conditions. Samples were analyzed for the homocysteine concentration and non-mercaptoalbumin/mercaptoalbumin ratio. RESULTS: The results revealed that a 65% heart rate reserve and 40 min of acute exercise increased plasma homocysteine concentration and non-mercaptoalbumin ratio. In the intra-condition comparison, the plasma Hcy concentration was significantly increased at Post 30 min (+ 0.83 ± 0.70 µmol/L, P = 0.003) compared with that at Pre in the exercise condition. Furthermore, 90 min after exercise, the blood non-mercaptoalbumin ratio was significantly increased (+ 0.35 ± 0.71%, P = 0.030) compared to Pre. CONCLUSION: These results indicate that the plasma Hcy concentration first increased, and then the non-mercaptoalbumin/mercaptoalbumin ratio increased as the elevated state was maintained. This study revealed that 65% heart rate reserve, 40 min of acute exercise increased plasma Hcy concentration and non-mercaptoalbumin ratio.

Tempol suppresses micronuclei formation in astrocytes of newborn rats exposed to 50-Hz, 10-mT electromagnetic fields under bleomycin administration.

A number of epidemiological studies have suggested that exposure to environmental and occupational electromagnetic fields (EMFs) contribute to the induction of brain tumors. The aim of this study was to investigate the mutagenetic effects of co-exposure to 50-Hz, 10-mT EMFs and bleomycin (BLM) using an ex vivo newborn rat astrocyte micronucleus assay. We also investigated whether the mutagenetic effects of EMFs were related to active oxygen species by using 4-hydroxy-2,2,6,6-tetramethyl piperidine-1-oxyl (tempol), a superoxide radical scavenger. Three-day-old male Sprague-Dawley rats were co-exposed to 50-Hz EMFs and BLM (5 or 10mg/kg body weight (BW)) in each group (n=6; total 6 group), and were co-exposed to 50-Hz EMFs and 10mg/kg BW BLM with administration of 200µmol/kg BW tempol in each group (total 4 group). Brain cells were dissociated into single cells, cultured for 96h, incubated with an antibody against glial fibrillary acidic protein, and stained with acridine orange. The frequency of micronucleated astrocytes was determined using a fluorescence microscope. The frequency of micronucleated astrocytes in the 10mg/kg BW bleomycin plus EMF exposure group (Mean±SD: 19.8±5.2‰) was 1.6 times higher than that in the 10mg/kg BW bleomycin plus sham-exposure group (Mean±SD: 12.7±3.3‰) (p<0.05). Analysis of the frequency of micronuclei in astrocytes after co-exposure to EMF and bleomycin for 72h and administration of tempol revealed that, in the EMF exposure group, the frequency of micronuclei in rats administered with 10mg/kg BW bleomycin and treated with tempol (Mean±SD: 11.2±1.9‰) was 40% of that in rats administered with the same dose of bleomycin and physiological saline (Mean±SD: 28.0±15.0‰) (p<0.01). Results of the current study suggested that the mechanism responsible for the elevated frequency of micronuclei in astrocytes of rats co-exposed to BLM and EMFs is related to active oxygen species.

Effect of Acute Dietary Nitrate Supplementation on the Venous Vascular Response to Static Exercise in Healthy Young Adults.

The purpose of this study was to test the hypothesis that acute intake of inorganic nitrate (NO3−) via supplementation would attenuate the venoconstriction and pressor response to exercise. Sixteen healthy young adults were assigned in a randomized crossover design to receive beetroot juice (BRJ) or an NO3−-depleted control beverage (prune juice: CON). Two hours after consuming the allocated beverage, participants rested in the supine position. Following the baseline period of 4 min, static handgrip exercise of the left hand was performed at 30% of the maximal voluntary contraction for 2 min. Mean arterial pressure (MAP) and heart rate (HR) were measured. Changes in venous volume in the right forearm and right calf were also measured using venous occlusion plethysmography while cuffs on the upper arm and thigh were inflated constantly to 30−40 mmHg. The plasma NO3− concentration was elevated with BRJ intake (p < 0.05). Exercise increased MAP and HR and decreased venous volume in the forearm and calf, but there were no differences between CON and BRJ. Thus, these findings suggest that acute BRJ intake does not alter the sympathetic venoconstriction in the non-exercising limbs and MAP response to exercise in healthy young adults, despite the enhanced activity of nitric oxide.

How elevated CO2 affects our nutrition in rice, and how we can deal with it.

Increased concentrations of atmospheric CO2 are predicted to reduce the content of essential elements such as protein, zinc, and iron in C3 grains and legumes, threatening the nutrition of billions of people in the next 50 years. However, this prediction has mostly been limited to grain crops, and moreover, we have little information about either the underlying mechanism or an effective intervention to mitigate these reductions. Here, we present a broader picture of the reductions in elemental content among crops grown under elevated CO2 concentration. By using a new approach, flow analysis of elements, we show that lower absorption and/or translocation to grains is a key factor underlying such elemental changes. On the basis of these findings, we propose two effective interventions-namely, growing C4 instead of C3 crops, and genetic improvements-to minimize the elemental changes in crops, and thereby avoid an impairment of human nutrition under conditions of elevated CO2.

[Occupational poisoning and biological exposure monitoring].

Biological exposure monitoring is available for detecting occupational toxic chemicals. It is possible to evaluate the exposure and adverse effects induced such the occupational toxic chemicals with biological exposure monitoring. It is used in health examination, for the recommendation of occupational exposure limits based on biological exposure monitoring, and for biological exposure indices of the American Conference of Governmental Industrial Hygienists (ACGIH).

Improvement of serum zinc levels in young Japanese women by provision of food information.

We investigated whether or not an intervention of providing food information improves serum Zn levels in ninety-two 18-20-year-old Japanese women. The mean serum Zn level of the participants was 73.09 ± 10.56 (mean ± SD) µg/dL, where 79 % of the participants had lower than the reference Zn level (80 µg/dL) proposed by the Japan Society for Biomedical Research on Trace Elements. Participants were divided into food information (INF) group, supplement (SPL) group, and control (C) group, and their serum Zn levels were measured before and after 2 weeks of intervention. The results showed that changes in serum Zn levels were (expressed in µg/dL): 71.23 ± 8.42 to 76.83 ± 12.22 in INF group (NS; not significant), 72.72 ± 10.77 to 84.07 ± 12.03 in SPL group (P < 0.01), and 72.69 ± 9.46 to 74.52 ± 11.44 in C group (NS). Percentage of normal subjects in serum Zn level (>79 mg/dL) were significantly increased in INF group (16.7 to 40%, P < 0.05) and SPL group (17.2 to 69%, P < 0.001) by each intervention. Food information only entailed a table of food items with high Zn content (card-type) and Zn intake menu (recipes). The results suggested that providing food information is effective in improving latent low Zn in young Japanese women.

Long-term intake of a high zinc diet causes iron deficiency anemia accompanied by reticulocytosis and extra-medullary erythropoiesis.

To elucidate the pathophysiology of zinc (Zn)-induced iron (Fe) deficiency anemia (IDA), we examined hemoglobin (Hb) concentrations, hematocrit (Ht) levels, numbers of circulating red blood cells (RBC) and reticulocytes, values of mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC), serum Zn, Fe and erythropoietin (EPO) concentrations and histopathological changes in the bone marrow, spleen and liver using rats fed with a standard or high Zn diet for 20 weeks. Rats fed with the high Zn diet exhibited a significant decrease in Hb concentrations, Ht levels and MCV, MCH and MCHC values, indicating microcytic hypochromic anemia characterized by Fe deficiency. Also, a marked decrease in serum Fe concentrations was seen in rats fed with the high Zn diet relative to rats fed with the standard diet. Interestingly, the number of RBC was comparable in both groups of rats, although a decrease in the number of RBC is ordinarily seen in IDA. There were reticulocytosis and extra-medullary erythropoiesis in the spleen and an increase in serum EPO concentrations in rats fed with the high Zn diet vs. those on the standard diet. These observations suggest that both reticulocytosis and extra-medullary erythropoiesis in the spleen played a role in maintaining the number of RBC in rats fed with the high Zn diet, preventing further progression of anemia. Further, increased production of EPO may be involved in the induction of reticulocytosis and extra-medullary erythropoiesis in the spleen.

Geonotoxicity study of illegal drug MDMA and its nitroso derivative N-MDMA by micronucleus and chromosomal aberration tests using Chinese hamsger lung fibroblast cell line.

OBJECTIVES: An increase in incidence of the illegal use of tablets containing 3,4-methylenedioxymethamphetamine hydrochloride (MDMA) has recently become a widespread social problem. MDMA ingested orally reacts with nitrite in the stomach and is synthesized intoN-nitroso-3,4-methylenedioxymethamphetamine (N-MDMA). The aim of this study is to investigate the genotoxic effects of MDMA and N-MDMA on the basis of the results of an in vitro micronucleus (MN) test and an in vitro chromosomal aberration (CA) test using a Chinese hamster lung fibroblast cell line (CHL/IU). METHODS: Tablets containing MDMA obtained from the Regional Bureau of the Ministry of Health, Labor and Welfare were purified, and N-MDMA was synthesized from MDMA in our laboratory. To evaluate the effects of MDMA and N-MDMA, the MN test established by our laboratory and the CA test in accordance with the guidelines for toxicity studies of drugs recommended by the Ministry of Health, Labor and Welfare were performed. RESULTS: In the MN test, no increased frequency of MNs was not found for MDMA. On the other hand, an apparently increased frequency of MNs was observed for N-MDMA. In the CA test, no CA was found for MDMA, but CA was observed for N-MDMA apparently. CONCLUSION: N-MDMA genotoxicity was observed in the MN and CA tests. However, no MDMA genotoxicity was observed.

Genotoxic effects of N-nitrosoketamine and ketamine as assessed by in vitro micronucleus test in Chinese hamster lung fibroblast cell line.

OBJECTIVES: Ketamine hydrochloride (KT) is a secondary amine that has been safely used as an injectable anesthetic and analgesic to avoid the production of nitroso compounds in the stomach. However, ketamine in the tablet form has recently become an abused, recreational drug. The aim of this study was to investigate the genotoxic effects of N-nitrosoketamine (NKT) and KT on the basis of an in vitro micronucleus (MN) test using a Chinese hamster lung fibroblast cell line (CHL/IU). METHODS: NKT was synthesized from KT in our laboratory. In the MN tests, CHL/IU cells were continuously treated with either NKT or KT for 24, 48, or 72 hours without the S9 mix. The cells were also treated with NKT or KT with or without the S9 mix for 6 hours, followed by a recovery period of 18, 42, or 66 hours (short-term treatment). The results were considered to be statistically significant when the p-values of both Fisher's exact test and the trend test were less than 0.05. RESULTS: After the short-term treatment with either NKT or KT with and without the S9 mix, the frequency of micronuclei significantly increased. However, the frequency of micronuclei did not significantly increase after the continuous treatment with either NKT or KT. Both NKT and KT were determined to be genotoxic in the short-term treatment with or without the S9 mix, but they were determined to be nongenotoxic in continuous treatment. CONCLUSION: Our findings suggest that NKT has a stronger genotoxic effect than KT.

Effect of static magnetic field on the induction of micronuclei by some mutagens.

OBJECTIVES: It is important to assess the risk of static magnetic fields (SMFs) on human health, because epidemiological studies have indicated that SMFs play a role in the development of diseases such as leukemia and brain tumor. In our environment, we have numerous chances to be exposed to not only SMFs but also many chemicals containing mutagens. The aim of this study is to investigate the effect of SMFs on the induction of micronuclei induced by some mutagens. METHODS: BALB/c mice were exposed to 4.7 tesla (T) SMF for 24 hr immediately after the injection of carboquone (alkylating agent), colcemid (spindle poison), mitomycin C (cross-linking agent), vincristine (spindle poison), sodium fluoride (a byproduct of aluminum plants under strong SMF) or 1-ethyl-1-nitrosourea (brain tumor-, gliomas- and thymic lymphoma-inducing chemical). RESULTS: The frequency of micronuclei induced by six mutagens increased after co-exposure to SMF. CONCLUSIONS: An additive/synergistic effect of SMF and chemicals was observed from the results of increased frequency of micronuclei induced by mutagens in mouse bone marrow erythrocytes.

The frequencies of micronuclei induced by cisplatin in newborn rat astrocytes are increased by 50-Hz, 7.5- and 10-mT electromagnetic fields.

OBJECTIVES: Epidemiological studies have suggested that exposure to environmental and occupational electromagnetic fields (EMFs) contribute to the induction of brain tumors, leukemia, and other neoplasms. The aim of this study was to investigate the genotoxic effects of exposure to 50-Hz EMFs. and of co-exposure to cisplatin, a mutagen and carcinogen, and 50-Hz EMFs, using an in vivo newborn rat astrocyte micronucleus assay. METHODS: Three day-old male Sprague-Dawley rats were co-exposed to 50-Hz EMFs and 1.25 or 2.5 mg/kg of cisplatin. Brain cells were dissociated into single cells and cultured for 96 hours, then stained with acridine orange and an antibody against glial fibrillary acidic protein. The frequency of micronucleated astrocytes was counted with a fluorescent microscope. RESULTS: The frequency of micronuclei was not increased in rat astrocytes exposed to EMFs alone. However, the frequencies of micronuclei in co-exposure to 2.5 mg/kg cisplatin and EMFs (7.5- and 10-mT) were significantly increased, compared with those in exposure to 2.5 mg/kg cisplatin alone (sham-exposure, 0-mT EMFs) for 72 hours (p<0.01). CONCLUSION: Exposure to EMFs alone did not have a genotoxic effect but co-exposure to EMFs increased the genotoxic activity induced by cisplatin. Our findings suggest that EMFs enhance the genotoxic effects of cisplatin.