Iron supplementation by intraperitoneal injection eliminates the accumulation of hepatic copper induced by excess calcium in rats.

Excess calcium is well known to induce iron deficiency. Furthermore, excess calcium increases hepatic copper concentration and decreases renal copper concentration. We investigated the effect of iron supplementation on the tissue distribution of copper in rats given a high-calcium diet. Male rats (5 weeks old) were divided into four groups; a control group, and three groups given a diet containing 5-fold higher calcium than its requirement and an intraperitoneal iron supplementation of 0, 1 or 2 mg/week as iron dextran. The animals were fed their respective experimental diets with or without iron supplementation for 4 weeks. Although the high-calcium diet had no effect on calcium concentrations in the liver, kidney, testis, spleen and plasma, it reduced haematocrit and iron concentrations in the liver, kidney and testis and the rats had a moderate iron deficiency. The iron supplementation restored to normal these signs of iron deficiency. The high-calcium diet increased hepatic copper concentration but decreased plasma copper concentration and ceruloplasmin activity, which was restored by the iron supplementation. The copper concentration in bile was neither affected by the high-calcium diet nor the iron supplementation. The high-calcium diet decreased the copper concentration in the kidney, which was not restored by the iron supplementation. These results suggest that secondary iron deficiency stimulates hepatic accumulation of copper in rats given excess calcium by suppressing copper efflux into the circulation. The reduced renal copper concentration by excess calcium is independent of the iron deficiency.

Response of biochemical markers of bone metabolism to exercise intensity in thoroughbred horses.

We studied the response of biochemical markers of bone metabolism to exercise intensity in horses. Four horses were walked on a mechanical walker for one week (pre-exercise). Then they performed low-speed exercise on a high-speed treadmill in the first week and medium-speed exercise in the second week and high-speed exercise in the third week of training. We measured two indices of bone resorption, serum hydroxyproline concentration and the urinary deoxypyridinoline/creatinine ratio, and serum osteocalcin (OC) concentration as an index of bone formation. Both indices of bone resorption gradually decreased during the experiment. Serum OC concentration did not change in the first week but was significantly lower in the second and the third weeks compared to in the pre-exercise period and in the first week. These results suggest that the low-speed exercise decreased bone resorption but did not affect bone formation, which possibly results in increasing bone mineral content and strengthening of bones. The high-speed exercise decreased bone formation and bone resorption, i.e., bone turnover was suppressed. The low-speed exercise may be preferable for increasing bone mineral content.

Molecular cloning and expression of bovine (Bos taurus) leptin receptor isoform mRNAs.

We characterized Bos taurus leptin receptor (Ob-R) isoform mRNAs as well as their expression in different tissues, including some adipose depots (perirenal, subcutaneous and intermuscular adipose tissues). Based on the GenBank database sequences of the bovine partial Ob-R, primers were designed to amplify cDNAs of bovine Ob-R isoforms. The full-length cDNAs of bovine the Ob-R isoforms were cloned by combination with 3'-and 5'-RACE. Three bovine Ob-R isoform cDNAs were cloned and the sequence analyses revealed that these cDNAs were bovine Ob-R isoforms, i.e., the long form (Ob-Rb), the middle form (Ob-Ra) and the short form (Ob-Rc). The open reading frames of Ob-Ra, Ob-Rb and Ob-Rc gene were 2688, 3498 and 2673 bp, respectively. The deduced amino acid sequences suggested that the isoforms were single transmembrane proteins, and differed in the C-terminal amino acid sequences. The amino acid sequence of these bovine Ob-R isoforms showed 73-75% identity compared with the corresponding mouse isoforms. The tissue-specific expression of the bovine Ob-R isoforms were measured by semi-quantitative RT-PCR. Expression of Ob-Rb was highest in liver, heart, spleen and kidney, with lower expression in lung and testis, and slight expression in muscle. Ob-Ra was highly expressed in liver and spleen, whereas moderate expression was observed in heart, testis, and muscle, and its expression was the lowest in lung and kidney. Ob-Rc mRNA was expressed in the liver, heart, testis, kidney and muscle, but not in the lung and spleen. In adipose tissues, higher expression of Ob-Ra and Ob-Rb mRNA was observed in intermuscular adipose tissue than in subcutaneous or perirenal adipose tissues. Ob-Ra mRNA level was positively correlated with Ob-Rb mRNA level in the adipose tissues (r=0.81, P<0.05). The results demonstrated that each Ob-R isoform mRNA was differentially expressed in various tissues of cattle, which may be involved in the difference of peripheral actions for leptin.

Follistatin rescues the inhibitory effect of activin A on the differentiation of bovine preadipocyte.

We investigated the effect of activin A and follistatin on the differentiation of bovine preadipocytes. Stromal-vascular (SV) cells containing preadipocytes were prepared from perirenal adipose tissue of approximately 30-month-old Japanese Black steers. After confluence, differentiation was induced by 1-methyl-3-isobutyl-xanthine, dexamethasone, insulin and troglitasone for 2 days, and then subsequently cultured for 6 days. The cells were treated with activin A during the induction of differentiation (the early phase of differentiation) or throughout the differentiation period. We measured the terminal differentiation markers such as glycerol-3-phosphate dehydrogenase (GPDH) activity, lipid accumulation, and the expression of adipocyte fatty acid-binding protein mRNA at the end of cultures. Activin A suppressed the induction of all differentiation markers regardless of the duration of treatment. The treatment with activin A also reduced the expression of peroxisome proliferator-activated receptor (PPAR) gamma and CCAAT/enhancer binding protein (C/EBP) alpha mRNAs without affecting the expression of C/EBPbeta mRNA. We also observed that follistatin completely rescued the inhibitory effect of activin A on bovine preadipocyte differentiation. Furthermore, the higher doses of follistatin increased GPDH activity even in the presence of activin A compared with the cells treated with neither activin A nor follistatin. Additionally, the SV cells expressed activin A and myostatin mRNAs. These results suggest that activin A inhibits bovine preadiopocyte differentiation via affecting transcriptional cascade upstream of PPARgamma and C/EBPalpha expressions, and that follistatin suppresses the inhibitory effect of activin A on bovine preadipocyte differentiation. Endogenous activin A and/or myostatin possibly inhibit the differentiation of bovine preadipocytes.

Myostatin inhibits differentiation of bovine preadipocyte.

We investigated the effect of myostatin on the differentiation of bovine preadipocyte. Stromal-vascular cells containing preadipocytes were prepared from perirenal adipose tissue of approximately 30-month-old Japanese Black steers. After confluence, the differentiation was induced by 1-methyl-3-isobutyl-xanthine, dexamethasone, insulin, and troglitasone for 2 days, and then subsequently cultured for 6 days. The cells were treated with myostatin during the induction of differentiation (the early phase of differentiation) or throughout the differentiation period. We measured the terminal differentiation markers such as glycerol-3-phosphate dehydrogenase activity, lipid accumulation, and the expression of adipocyte fatty acid-binding protein mRNA at the end of cultures. The treatment with myostatin throughout the differentiation period severely suppressed the induction of all differentiation markers. The treatment with myostatin in the early phase of differentiation also suppressed the induction of terminal differentiation markers but three-fold higher dose of myostatin was required for the suppression compared with its treatment throughout the differentiation period. Myostatin treatment reduced the expression of peroxisome proliferator-activated receptor (PPAR) gamma mRNA and interfered with the induction of CCAAT/enhancer binding protein (C/EBP) alpha mRNA. We also observed that follistatin stimulates preadipocyte differentiation in the presence of myostatin. These results suggest that myostatin inhibits bovine preadiopocyte differentiation through suppressing PPARgamma and C/EBPalpha mRNA expressions and that follistatin counteracts the suppressive effect of myostatin.

Excess calcium increases bone zinc concentration without affecting zinc absorption in rats.

We examined zinc (Zn) metabolism in rats given diets containing excess calcium (Ca). Rats were given phytate-free diet containing 5 g Ca/kg (control), 12.5 g Ca/kg, or 25 g Ca/kg for 4 wk in Experiment 1. The dietary treatment did not affect Zn concentration in the plasma, testis, kidney, spleen and liver; however, Zn concentration in the femur and its cortex was significantly higher in rats given diet containing 25 g Ca/kg than in other rats. Rats were given phytate-free diet containing 5 g Ca /kg or 25 g Ca /kg for 4 wk in Experiment 2. After 12-h food deprivation, rats were given a diet extrinsically labeled by 67Zn with dysprosium as a fecal marker for 4 h. Feces were collected from 1 d before administration of the labeled diet to 5 d after administration. Excess Ca did not affect the true absorption of Zn and its endogenous excretion but increased femoral Zn. These results suggest that excess Ca improves Zn bioavailability without affecting Zn absorption when diets do not contain phytate.

Relationship between plasma vitamin C and serum diagnostic biochemical markers in lactating cows.

We investigated the relationship between plasma vitamin C concentration and serum levels of some diagnostic biochemical markers in 118 lactating Holstein cows. Blood sample was collected once from each cow and we measured the plasma vitamin C concentration and the serum levels of glucose, beta-hydroxybutyrate, free fatty acids, triacylglycerol, total cholesterol, albumin, total bilirubin, alkaline phosphatase, aspartate aminotransferase and gamma-glutamyltransferase. The regression of plasma vitamin C with each serum diagnostic biochemical marker indicated that the vitamin C concentration significantly decreased as glucose, alkaline phosphatase or aspartate aminotransferase level increased and as total cholesterol or albumin concentration decreased. Furthermore, the plasma vitamin C concentration was significantly lower in the cows showing that each of these marker levels was out of its reference interval than in the cows showing that the marker level was within its reference interval. The significant correlations were observed among total cholesterol, albumin, alkaline phosphatase and aspartate aminotransferase levels, to which the glucose concentration was not related. These results showed that the plasma vitamin C concentration was low in the cows that had concurrently low levels of total cholesterol and albumin, and high levels of alkaline phosphatase and aspartate aminotransferase. Therefore, a hepatic malfunction possibly decreases plasma vitamin C concentration through suppressing vitamin C production. On the other hand, the high level of glucose possibly decreases plasma vitamin C concentration through suppressing vitamin C recycling.

Plasma concentration of vitamin C in dogs with a portosystemic shunt.

Most mammals, including dogs, synthesize vitamin C in the liver. We measured the plasma concentration of vitamin C to assess the body vitamin C status in 15 dogs with a portosystemic shunt (PSS). The plasma biochemical parameters indicated liver abnormalities in all the dogs. In contrast, the plasma concentration of vitamin C ranged from 2.21 to 9.03 mg/L in the 15 dogs and was below the reference range (3.2 to 8.9 mg/L) in only 2 dogs. These findings suggest that vitamin C status is not impaired in dogs with PSS.

Activin A inhibits differentiation of 3T3-L1 preadipocyte.

We investigated the effect of activin A on differentiation of 3T3-L1 preadipocyte. Activin A suppressed the induction of terminal differentiation markers such as glycerol-3-phosphate dehydrogenase (GPDH) activity, lipid accumulation, and the expression of adipocyte fatty acid-binding protein (aP2) mRNA when the cells were treated with activin A throughout the differentiation period. Activin A treatment during the early phase decreased GPDH activity and aP2 mRNA level, and also reduced the expression of peroxisome proliferator-activated receptor (PPAR) gamma and CCAAT/enhancer binding protein (C/EBP) alpha mRNAs without affecting the expressions of the active isoforms of C/EBPbeta and its mRNA. On the other hand, activin A treatment had no effect on the mitotic clonal expansion. These results indicate that activin A inhibits adipogenesis via affecting the transcriptional factor cascade upstream of PPARgamma expression.

Effect of exercise on iron metabolism in horses.

We investigated the effect of exercise on iron metabolism in horses. Four horses were walked on a mechanical walker for 1 wk (pre-exercise). They then performed moderate exercise on a high-speed treadmill in the first week of the exercise and relative high in the second week and high in the third week. Serum iron was significantly lower in the third week of exercise than in the pre-exercise. Transferrin saturation (TS) was significantly lower in the first and third weeks of exercise than in the pre-exercise. Serum haptoglobin was significantly lower in the first week of exercise than in the pre-exercise and further significantly lower in the second and third weeks than in the first. The packed cell volume did not change during the experiment. The exercise significantly increased the apparent absorption of iron. Urinary iron excretion did not change throughout the experiment. Sweat iron loss did not change during the exercise. The exercise significantly increased iron balance. We considered that hemolysis is induced by moderate exercise and is further enhanced by heavy exercise, which decreases serum iron and TS. However, the increase in iron absorption compensates for the adverse effect of exercise on iron status. Therefore, exercise does not induce anemia in horses.

Plasma vitamin C concentration is not related to the incidence of ketosis in dairy cows during the early lactation period.

Many animals including cattle can synthesize vitamin C from glucose. The objective of this study was to investigate plasma vitamin C concentration in ketotic cows during the early lactation period because glucose supply for vitamin C synthesis might be limited in these cows. We measured plasma beta-hydroxybutyrate (BHBA) concentration in 118 cows within 2 months after parturition. Subclinical/clinical ketosis was quantitatively determined using a plasma BHBA threshold of 1,200 microM. Plasma glucose concentration was lower in the ketotic cows than in the control cows but plasma vitamin C concentration did not differ between the control and the ketotic cows. Then we measured plasma vitamin C, BHBA and glucose levels in 7 cows during the periparturient period. Plasma BHBA increased and plasma glucose decreased after parturition but plasma vitamin C did not change. These results indicate that plasma vitamin C is not related to the incidence of ketosis in the early lactation period. We suggest that ketotic cows have the ability to produce vitamin C to meet its requirement in the early lactation period although glucose supply is not sufficient for milk production. Vitamin C synthesis is possibly given a high metabolic-priority for glucose in lactating cows.

[Growth and magnesium].

Magnesium is one of essential minerals for humans and animals. Mg has important roles in energy metabolism, protein synthesis, bone metabolism and muscle contraction. Mg deficiency causes tetany, muscular incoordination, growth retardation and death. Mg is necessary for normal growth, however the mechanism is unclear. In this article, we will describe Mg metabolism, Mg deficiency, and the relationship Mg and growth.

On the reflex coactivation of ankle flexor and extensor muscles induced by a sudden drop of support surface during walking in humans.

Recent studies have revealed that the stretch reflex responses of both ankle flexor and extensor muscles are coaugmented in the early stance phase of human walking, suggesting that these coaugmented reflex responses contribute to secure foot stabilization around the heel strike. To test whether the reflex responses mediated by the stretch reflex pathway are actually induced in both the ankle flexor and extensor muscles when the supportive surface is suddenly destabilized, we investigated the electromyographic (EMG) responses induced after a sudden drop of the supportive surface at the early stance phase of human walking. While subjects walked on a walkway, the specially designed movable supportive surface was unexpectedly dropped 10 mm during the early stance phase. The results showed that short-latency reflex EMG responses after the impact of the drop (<50 ms) were consistently observed in both the ankle flexor and extensor muscles in the perturbed leg. Of particular interest was that a distinct response appeared in the tibialis anterior muscle, although this muscle showed little background EMG activity during the stance phase. These results indicated that the reflex activities in the ankle muscles certainly acted when the supportive surface was unexpectedly destabilized just after the heel strike during walking. These reflex responses were most probably mediated by the facilitated stretch reflex pathways of the ankle muscles at the early stance phase and were suggested to be relevant to secure stabilization around the ankle joint during human walking.

Effects of loading and unloading of lower limb joints on the soleus H-reflex in standing humans.

OBJECTIVE: To investigate the effects of loading and unloading of the lower limb joints on the soleus H-reflex in standing humans. METHODS: H-reflexes were elicited in the soleus muscle in subjects standing on a force platform in a water tank under the following loading conditions of the ankle and knee joints: control condition; reduced loads of -10 and -20 N; imposed loads of 10 and 20 N. The joint loading was altered by changing the combinations of buoys and weights attached to the lower limb segments, while total body weight was kept constant. RESULTS: As the ankle- or knee-joint load was reduced, the H-reflex was significantly enhanced compared to that under the control condition. In contrast, the H-reflex was decreased as the ankle- or knee-joint load was increased. In both cases, similar levels of background activity were recorded. CONCLUSIONS: The present results suggest that joint afferents might mediate the suppression of the soleus H-reflex in standing humans. However, the identification of the receptors and/or the mechanisms cannot be addressed under the current experimental set up. SIGNIFICANCE: The results of this study give some basic insights into reflex control in an upright posture.

Red yeast rice extracts suppress adipogenesis by down-regulating adipogenic transcription factors and gene expression in 3T3-L1 cells.

The effects of red yeast rice extracts (RE) on adipocyte differentiation of 3T3-L1 cells were studied. RE were extracted from embryonic rice fermented with red yeast (Monascus ruber). These extracts significantly decreased glycerol-3-phosphate dehydrogenase (GPDH) activity and lipid accumulation, a marker of adipogenesis, in a dose-dependent manner. Moreover, mRNA expression levels of both CCAAT/enhancer-binding protein (C/EBP) alpha and peroxisome proliferator-activated receptor (PPAR) gamma, the key adipogenic transcription factors, were markedly decreased by RE. RE also inhibited the expression of PPARgamma at protein levels. RE decreased significantly gene expression of adipocyte fatty acid binding protein (aP2) and leptin, which are adipogenic marker proteins and C/EBPalpha and PPARgamma target genes. These results suggest that the inhibitory effect of RE on adipocyte differentiation might be mediated through the down-regulated expression of adipogenic transcription factors and other specific genes.

PCR detection of bovine mitochondrial DNA derived from meat and bone meal in feed.

Because bovine meat and bone meal (MBM) is thought to be a major source of bovine spongiform encephalopathy, we developed a PCR-based method for detection of bovine MBM in animal feed. We isolated bone particles from feed containing bovine MBM using a separation technique based on specific gravity and then washed bone particles with sodium hypochlorite solution and an EDTA-proteinase K solution. The mitochondrial DNA was extracted from bone particles and amplified using PCR with cattle-specific primers. Bovine DNA was not detected in a milk replacer containing dried skim milk and dried whey, but bovine DNA was detected in the milk replacer that was mixed with bovine MBM. Other cattle-derived materials in feeds did not interfere with the selective detection of bovine MBM. This method allowed detection of bovine mitochondrial DNA in feed with 0.1% added bovine MBM. When the treatment with sodium hypochlorite was excluded, bovine DNA derived from MBM could not be distinguished from bovine DNA derived from other bovine materials. However, the exclusion of this treatment improved the detection limit of bovine MBM in feed. This method appears suitable for the selective detection of bovine MBM in feed.

Experimental study of decubitus ulcer formation in the rabbit ear lobe.

An animal model of decubitus ulcer was created with the use of ear lobes of Japanese white rabbits. When the strength of the cyclic compressions and the duration of the cycles of compression and release are adjusted, the model successfully reproduced the four grades used to characterize decubitus ulcer. Compressions were recorded with video microscopy to continuously monitor the changes in tissue blood flow, in both the compressed and surrounding regions. This model is unique insofar as the blood-flow characteristics are clearly visible before, during, and after compression. Because long-term observation is possible in a living-body model, our study can easily be extended.

Absorption of zinc from dietary casein phosphopeptide complex with zinc in rats given a soybean protein-based diet.

The absorption of zinc (Zn) in the form of casein phosphopeptide (CPP) complex was compared with that of its chloride form in rats given a soybean protein-based diet. We prepared 67Zn complex with CPP (67Zn-CPP). Male rats were given a diet containing ZnCl2 in the preliminary period. After overnight food deprivation, they were fed a test meal labeled 67Zn-CPP or 67ZnCl2 (4 g Zn-free diet + 0.12 mg 67Zn) with 0.5 mg Dysprosium (Dy) as a fecal marker. Feces were collected for 5 d and analyzed for 67Zn isotopic enrichment and Dy concentration with an inductively coupled plasma mass spectrometer. Fecal Dy excretion closely paralleled that of 67Zn, and more than 89% of the administered Dy was recovered in the feces collected for 5 d. Moreover, the Zn source did not affect the excretion pattern of 67Zn. Since Dy and 67Zn were almost excreted within 3 d after the administration, the apparent absorption of 67Zn was calculated from the pooled data for 3 d. The source of Zn did not affect the apparent absorption of 67Zn. These results suggested that dietary Zn in the form of CPP complex did not show higher absorbability in rats.

Nitric oxide suppresses preadipocyte differentiation in 3T3-L1 culture.

Nitric oxide (NO) is an important chemical messenger controlling many physiological functions, involving cell proliferation, and differentiation. The purpose of this study was to investigate the effect of NO on adipocyte differentiation using a murine preadipocyte cell line, 3T3-L1. The treatment with a NO donor, 1-hydroxy-2-oxo-3,3-bis(2-aminoethyl)-1-triazene (NOC18), reduced some markers of adipocyte differentiation such as glycerol-3-phosphate dehydrogenase activity, and intracellular lipid accumulation. To examine whether these effects of NOC18 on adipocyte differentiation markers are due to its cytotoxity, lactate dehydrogenase (LDH) release from the cells were measured. NOC18 did not affect LDH release into the culture medium. Thus, the suppressive actions of NO donor were unlikely to result from its cytotoxicity. Peroxisome proliferator-activated receptor (PPAR) gamma is a critical transcription factor for adipocyte differentiation and adipocyte fatty acid binding protein (aP2) gene is one of its targets. Protein expression of PPARgamma was not diminished by NOC18 treatment, although mRNA expression of aP2 was reduced. Electrophoretic mobility shift assay showed that NOC18 interfered with the DNA binding activity of PPARgamma. Therefore, the present experiment suggest that NO suppresses adipocyte differentiation through suppressing the transcriptional activity of PPARgamma, without suppressing its expression level.

Phase-transition phenomena of 0.8 microm superfluid 3He slab.

We have investigated the transition phenomena of superfluid 3He in thin 0.8 microm slabs with a cw-NMR method. We found that, just below the phase-transition temperature, only the A phase appeared at any pressure. At lower temperatures, the phase transition to the B phase occurred between 0.3 and 2.74 MPa. We obtained a universal critical thickness delta as a function of pressure. When the reduced slab thickness, d/xi(T), is smaller than delta, only the A phase becomes stable.