Correlation between charge density wave phase transition and hydrogen adsorption in 1T-TaS2thin film devices.

Thin films of tantalum disulfide in the 1T-polytype structural phase (1T-TaS2), a type of metallic two-dimensional (2D) transition metal dichalcogenides (TMDs), are reactive to H2. Interestingly, in the incommensurate charge-density wave (ICCDW) phase with a metallic state, the electrical resistance of the 1T-TaS2thin film decreases when H2is adsorbed on it and returns to its initial value upon desorption. In contrast, the electrical resistance of the film in the nearly commensurate CDW (NCCDW) phase, which has a subtle band overlap or a small bandgap, does not change upon H2adsorption/desorption. This difference in H2reactivity is a result of differences in the electronic structure of the two 1T-TaS2phases, namely, the ICCDW and NCCDW phases. Compared to other semiconductor 2D-TMDs such as MoS2and WS2, the metallic TaS2has been theoretically proven to capture gas molecules more easily because Ta has a stronger positive charge than Mo or W. Our experimental results provide evidence of this. Notably, this study is the first example of H2sensing using 1T-TaS2thin films and demonstrates the possibility of controlling the reactivity of the sensors to the gas by changing the electronic structure via CDW phase transitions.

Salt Restriction Affects the Excretions of Minerals (Na, K, Ca, Mg, P and Zn) in the Second Voided Fasting Early Morning Urine.

The plasma concentrations of mineral (sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), phosphorus (P), and zinc (Zn)) are kept within narrow ranges to maintain homeostasis; hence, it is difficult to use them as indicators of nutritional status. We selected the excretion of these minerals in the second voided fasting early morning urine (EMU) as potential indicators of nutritional status. We previously reported that Na restriction caused a negative balance of Ca and Mg. Therefore, Na restriction can cause changes in EMU-minerals. This study aimed to examine the relationship between dietary Na restriction and urinary mineral excretion. The study lasted for 21 d, including 16 d of balance period and 3 d of recovery period. The participants (11 healthy young women) were divided into the Na restriction group (n=5) (NaCl: 6 g/d) and control group (n=6) (NaCl: 12 g/d). The Na restriction group changed to the control diet (NaCl: 12 g/d) during only the recovery period. The EMU-Na, Ca, Mg, P and Zn in the Na restriction group significantly decreased compared with that of the control group. The EMU-Na, K, Ca, Mg, and Zn in the group with NaCl intake of 6 g/d significantly decreased compared with that of the group with NaCl intake of 12 g/d (in the Na restriction group). We conclude that the decrease in excretion of Na, Ca, Mg and Zn in the EMU can lead to Na restriction. This result can serve as basis when considering EMU as an indicator of mineral status.

Dietary Salt (Sodium Chloride) Requirement and Adverse Effects of Salt Restriction in Humans.

Inevitable sodium loss under sodium restriction must not be construed as evidence for the estimated average requirement (EAR) for sodium (Na) in humans. We conducted human mineral balance studies to determine the EAR for some minerals (Na, K, Ca, Mg, P, Zn, Fe, Cu and Mn). Na concentration in arm sweat was low while those of calcium (Ca) and magnesium (Mg) were high, during relatively heavy bicycle-ergometer exercise under relatively low Na intake (100 mmol/d). This suggests that Na was released from the bone, the sole pool of Na, with Ca and Mg. Additionally, the negative balances of Ca and Mg was observed under a relatively low sodium intake (100 mmol/d) even with the sufficient supply and intake of Ca and Mg into human body. Finally, we found no correlation between the Na intake and the Na balance, while the Na-intake was correlated significantly to the balances of K, Ca and Mg. The Na intake necessary to keep the balances of Ca and Mg positive was calculated to be 68 mg/kg body weight/d. To learn the signs and symptoms of low sodium intake, we compared the results of a metabolic study in which subjects consumed diets with 6 g and 12 g salt/d respectively. The blood pressure decreased only with the 6 g/d group. Fecal moisture contents of the 6 g/d group were lower than for the 12 g/d group, suggesting the fecal Na was strongly reabsorbed with water when the dietary Na was insufficienct. Indiscriminate Na restriction may have adverse effects on health.

Estimated equilibrated dietary intakes for nine minerals (Na, K, Ca, Mg, P, Fe, Zn, Cu, and Mn) adjusted by mineral balance medians in young Japanese females.

The present study sought to determine estimated equilibrated dietary intakes (EEDIs) for nine essential minerals: sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), phosphorus (P), iron (Fe), zinc (Zn), copper (Cu), and manganese (Mn), using data from 17 human mineral balance studies conducted from 1986 to 2007 (subjects=178). Among these studies, two used male subjects, two subjected some or all subjects to sodium restriction, and one study utilized a low protein diet; these subjects were not included in the present analysis. Consequently, data from 13 studies of young female subjects (n=131) consuming a standard diet were selected. Balance distribution medians for six of the minerals (Na, K, Mg, Fe, Zn and Cu) were positive, so the data were adjusted to set the medians of the balances to zero. Medians for the other minerals (Ca, P and Mn) were close to zero and were not adjusted. Intake and balance for each mineral were divided by body weight (BW), lean body mass (LBM), and standard body weight (SBW), which was calculated using height and standard body mass index (BMI=22), and EEDIs were calculated as the intercept of a simple regression equation. When relationships between intake and balance of a mineral were not significant in the regression equation, a significant regression equation comparing intake and balance of another mineral was used to calculate the intercept. Significant simple regression equations were not obtained from any of the three parameters of Na or Zn, or for two of the parameters of P; thus, K, Fe and Ca balances were used to determine the intercepts for Na, Zn and P, respectively. EEDIs for the minerals were: Na (67.9, 89.0, 62.5), K (39.5, 53.5, 37.4), Ca (11.0, 14.4, 10.1), Mg (4.18, 5.51, 3.86), P (18.7, 24.6, 17.3) (mg/kg BW/d, mg/kg LBM/d, mg/kg SBW/d), Fe (180, 237, 165), Zn (181, 241, 166), [corrected] Cu (32.3, 42.6, 29.7), [corrected] Mn (55.1, 72.1, 50.7) (µg/kg BW/d, µg/kg LBM/d, µg/kg SBW/d), respectively. These values are nearly identical to the mean dietary intakes.

Equilibrium energy intake estimated by dietary energy intake and body weight changes in young Japanese females.

To determine the energy intake (EI) required to maintain body weight (equilibrium energy intake: EEI), we investigated the relationship between calculated energy intake and body weight changes in female subjects participating in 14 human balance studies (n=149) conducted at the National Institute of Health and Nutrition (Tokyo). In four and a half studies (n=43), sweat was collected from the arm to estimate loss of minerals through sweating during exercise on a bicycle ergometer; these subjects were classified in the exercise group (Ex G). In nine and a half experiments (n=106) subjects did not exercise, and were classified in the sedentary group (Sed G). The relationship between dietary energy intake (EI) and body weight (BW) changes (ΔBW) was analyzed and divided by four variables: body weight (BW), lean body mass (LBM), standard body weight (SBW), and body surface area (BSA). Equilibrium energy intake (EEI) and 95% confidence interval (CI) for EEI in Ex G were 34.3 and 32.8-35.9 kcal/kg BW/d, 32.0 and 30.8-33.1 kcal/kg SBW/d, 46.3 and 44.2-48.5 kcal/kg LBW/d, and 1,200 and 1,170-1,240 kcal/m(2) BSA/d, respectively. EEI and 95% CI for EEI in Sed G were 34.5 and 33.9-35.1 kcal/kg BW/d, 31.4 and 30.9-32.0 kcal/kg SBW/d, 44.9 and 44.1-45.8 kcal/kg LBM/d, and 1,200 and 1,180-1,210 kcal/m2 BSA/d, respectively. EEIs obtained in this study are 3 to 5% higher than estimated energy requirement (EER) for Japanese. In five out of six analyses, EER in a population (female, 18-29 y, physical activity level: 1.50) was under 95% CI of EEI obtained in this study.

Summer treatment program for children with attention deficit hyperactivity disorder: Japanese experience in 5 years.

In 2005 we established the first American-style summer treatment program (STP) for children with attention deficit hyperactivity disorder (ADHD) located outside North America. This program was based on methods established by professor Pelham and has been used in a number of studies and at a number of sites in the USA. A total of 137 children diagnosed with ADHD, ranging in age from 6 to 12 years, participated in at least one of five annual summer treatment programs in Kurume city, Japan, during 2005-2009. The duration of the STP was 2 weeks in 2005, 2008, and 2009; 3 weeks in 2006 and 2007. A set of evidence-based behavioral modification techniques comprising the STP behavioral program (e.g., point system, daily report card, positive reinforcement, time out) was used. We also assessed the cognitive function of individual children before and after STP using the CogState(R) batteries. Every year, regardless of the duration of the STP, most children showed positive behavioral changes in multiple domains of functioning, demonstrated by significant improvement in points earned daily, which reflect behavior frequencies. Cognitive functions, particularly the rate of anticipatory errors in executive function, significantly improved after the STP, suggesting that STP has positive effects not only on behavioral aspects but also on some cognitive functions. Further studies are necessary to confirm this finding by studying sequential cognitive function of age-matched children who do not attend STP.

Inhibitory effect of the extracts from Thai medicinal plants on iNOS expression in mouse macrophage RAW 264.7.

In the present study, we screened the inhibitory effect of the extract from 50 Thai medicinal plants on an inducible-nitric oxide synthase (iNOS) expression induced by lipopolysaccharide (LPS) in mouse macrophages RAW 264.7. From this screening, the extracts of root bark of Clausena guillauminii, C. lunulata, and C. excavata (Rutaceae) were found as the extracts which showed potent inhibitory effect on the iNOS protein expression in concentration-dependent manner. Furthermore, hydrophobic active components may exist in C. guillauminii.

Inhibitory effect of oxycoumarins isolated from the Thai medicinal plant Clausena guillauminii on the inflammation mediators, iNOS, TNF-alpha, and COX-2 expression in mouse macrophage RAW 264.7.

In the present study, we investigated the inhibitory effect of the known oxycoumarins poncitrin (3), osthol (4), and xanthoxyletin (5), newly isolated from Clausena guillauminii (Rutaceae), together with the known carbazoles heptaphylline (1) and 7-methoxyheptaphylline (2) on inducible-nitric oxide synthase (iNOS) expression induced by lipopolysaccharide (LPS) and the NO generation in RAW 264.7 mouse macrophages. Isolation of active oxycoumarins was guided by Western blot analysis of iNOS protein expression. These oxycoumarins showed an inhibitory effect on iNOS protein expression at 10 microM. Further examination of the inhibitory effects of these compounds on inflammation mediators revealed that the synthesis of nitric oxide (NO) and the protein expression of tumor necrosis factor-alpha (TNF-alpha) and cyclooxygenase-2 (COX-2) were inhibited by 5. It was expected that these compounds show anti-inflammatory activities.

The structure-activity relationship between oxycoumarin derivatives showing inhibitory effects on iNOS in mouse macrophage RAW264.7 cells.

We have investigated the structure-activity relationship between 63 natural oxycoumarin derivatives and their effects on the expression of inducible-nitric oxide synthase (iNOS) induced by lipopolysaccharide. The protein expression of iNOS was screened by Western blot analysis, and four 5,7-dimethoxycoumarins were selected as potent inhibitors of iNOS expression. In terms of structural specificity, the methoxyl group on C-5 and C-7 and the short alkyl chain (1-5 carbons) on C-6 may be essential for the potent activities. These compounds also showed inhibitory effects on nitric oxide generation and mRNA expression of inflammatory mediators, namely, iNOS and COX-2. Interestingly, the inhibitory effect on mRNA expression was specific for iNOS and was not detected for neuronal NOS. It is expected that these compounds will show anti-inflammatory activities via inhibition of the expressions of iNOS and COX-2.

Molybdenum balance in healthy young Japanese women.

The absorption and balance of molybdenum (Mo) were examined in 43 healthy young Japanese women in four metabolic studies performed once a year from 2001 to 2004. In each year, an 18-d metabolic study, including two successive balance study sessions of 4 d, was designed and four kinds of dietary menus were supplied to the subjects periodically. Since the protein sources of the menus were specified in 2001-2003, and soybean products were poor in 2001 and 2002 and rich in the 2003, Mo intake in 2001 and 2002 was about 150microg/d while that in 2003 reached 318microg/d. In 2004, the protein sources were not specified and Mo intake was 217microg/d. This range of Mo intake overlapped that in the Japanese population. When the results of the four studies were pooled, Mo balance was calculated as 0.09+/-0.37microg/d/kg (mean+/-SD), and no significant relationship (r=0.142) was observed between the intake and balance. Between the apparent absorption (Y) and the intake (X), a significant (r=0.988, p<0.001) positive linear regression (Y=0.927X-0.523) was observed. Similarly, a significant (r=0.960, p<0.001) positive linear regression was observed between Mo intake and urinary excretion. These results indicate that more than 90% of Mo contained in a routine dietary menu is absorbed, most of Mo absorbed is excreted in urine, and Mo balance is in equilibrium in the general Japanese population.

Effects of a 21 day metabolic study on serum opsonic activity in female college students, assessed by a chemiluminescence technique.

A metabolic study to evaluate nutritional balance, in which subjects have to eat all the foods supplied and maintain a set schedule, is thought to be stressful for the subjects. The effects of stress on the immune system have been studied extensively. However, there are no studies of non-specific immunological changes during a metabolic study. Serum opsonic activity (SOA) is a direct and suitable indicator of non-specific humoral immunity. In this study, we used luminol-dependent chemiluminescence (LmCL) to measure reactive oxygen species (ROS) generation from pooled human neutrophils as an indicator of SOA. We also measured serum immunoglobulin levels and plasma myeloperoxidase (MPO) activity. Eleven female college students took part in this 21 day metabolic study after giving their written informed consent. The results obtained suggest that the metabolic study has almost no effect on immunoglobulin levels. According to MPO levels, neutrophils in vivo may be deactivated to some minor extent. In contrast to these results, peak time (PT) and peak height (PH) of LmCL were changed significantly during the metabolic study. In conclusion, SOA increased during the 21 day metabolic study. There was no significant correlation between SOA and serum immunoglobulin levels on any of the study days.

Moisture and mineral content of human feces--high fecal moisture is associated with increased sodium and decreased potassium content--.

BACKGROUND: The origin of moisture in diarrhea feces is unknown but may represent the unabsorbed part of intestinal contents or alternatively, body fluid excreted into the digestive canal. If the latter mechanism contributes to moisture in the feces, active transport of water (H2O) associated with ion exchange channels may be involved. OBJECTIVE: To investigate this possibility we measured the content of moisture and minerals (sodium [Na], potassium [K], calcium [Ca], magnesium [Mg], phosphorus [P], zinc [Zn], iron [Fe], copper [Cu] and manganese [Mn]) in feces collected during a 12-d metabolic study on 11 young Japanese female students. DESIGN: The study was carried out as part of a human mineral balance study. The same quantity of food was supplied to each of the subjects throughout the study without consideration of body weight. Fecal specimens were collected throughout the study and were separated into those originating from the diet during the balance period based on the appearance of the ingested colored marker in the feces. RESULTS: The moisture content of the feces ranged between 53 and 92%. Na content in the feces was low and stable when the moisture content was below 80%, whereas it increased up to serum levels when the moisture content increased above 80%. On the other hand, K content increased when compared to dry matter base. However, when comparing concentration/g moisture, K content increased when moisture was below 70%, but decreased when this rose above 70%.

Equilibrium intakes of calcium and magnesium within an adequate and limited range of sodium intake in human.

In the previous analysis of our human mineral balance studies, we demonstrated positive correlations between the balances of calcium (Ca) and magnesium (Mg) and sodium (Na) intake in the range of 3.06 and 4.06 g/d or 43.71 and 96.40 mg/kg body weight (BW)/d, but there was no correlation between Na intake and Na balance. This suggested that the balances of Ca and Mg are affected by Na intake. Therefore, in the current study, we recalculated equilibrium intakes for Ca and Mg when balances of their intakes and outputs were equal to zero within the above Na range to reduce the effects of Na intake. From 1986 to 2000, 90 volunteers (10 male, 80 female; age 18 to 28 y) took part in 9 mineral balance studies. The balance periods ranged from 8 to 12 d, with adaptation periods of 2 to 4 d. The dietary intakes of Ca and Mg ranged from 294 to 719 and 154 to 334 mg/d, or from 4.83 to 15.07 and 2.44 to 6.42 mg/kg BW/d, respectively. Intake of Ca significantly correlated with Ca balance (r2 = 0.268; p < 0.0001). When the balance was equal to zero, the mean value and upper limit of the 95% confidence interval for the regression equation between intake vs. balance were 10.072 and 10.660 mg/kg BW/d, respectively. Mg intake correlated significantly with Mg balance (r2 = 0.141, p = 0.003). When the balance was equal to zero, the mean value and upper limit of the 95% confidence interval for the regression equation between intake and balance were 4.078 and 4.287 mg/kg BW/d, respectively.

Positive correlation between dietary intake of sodium and balances of calcium and magnesium in young Japanese adults--low sodium intake is a risk factor for loss of calcium and magnesium--.

The content of calcium (Ca) and magnesium (Mg) in sweat during exercise is considerably higher during a relatively low intake of sodium (Na) of 100 mmol/d than with an intake of 170 mmol/d. For this reason and also because Ca and Mg have a negative balance with a Na intake of 100 mmol/d, we analyzed the relationship between Na intake and balances of Ca and Mg in data from 11 balance studies. From 1986 to 2000, 109 volunteers (23 males, 86 females) with an age range of 18 to 28 y took part in mineral balance studies. The balance periods ranged from 5 to 12 d. In a given experiment, the diet of each subject contained the same quantity of food, although this varied between experiments, and was supplied during the balance period without consideration of body weight. In the data of all the studies (n= 109), the balances of Ca and Mg did not correlate positively with Na intake. However, when the data of the highest Na study were excluded, the balances of Ca and Mg correlated positively with Na intake. The mean value for the regression equation between Na intake and Ca and Mg balances when the respective balance was equal to zero were, 63.308 mg Na/kg BW/d (Ca: n=96, r2=0.134) and 60.977 mg Na/kg BW/d (Mg: n=96, r2=0.268), respectively. These values are considerably higher than Na requirements estimated by inevitable Na loss. Low dietary Na may therefore be a risk factor for maintaining positive balances of Ca and Mg.

Sodium and potassium balances in Japanese young adults.

This study was conducted to estimate the requirements of sodium (Na) and potassium (K) in Japanese young adults. From 1986 to 2000, 109 volunteers (23 males, 86 females), ranging from 18 to 28 y old, took part in 11 mineral balance studies after written informed consent had been obtained. The duration of the study periods ranged from 5 to 12 d, with a 2-4 d adaptation period. Foodstuffs used in each study were selected from those commercially available. The Na and K content of the diet, feces, urine and sweat were measured by atomic absorption spectrophotometer. The results of a study in which Na intake was 6.87 g/d (ca. 300 mmol/d), the highest of all the studies, showed apparent positive Na balances. In contrast, another study in which Na intake was 2.21 g/d (ca. 100 mmol/d), the lowest of all the studies, showed apparent negative Na balances. These two studies seemed to differ from the other studies, as shown by regression equations calculated from either data of all the studies (n= 109) or data that did not include the two studies (n=90). The dietary intakes of Na and K ranged between 38.56-142.23 and 26.77-74.42 mg/kg body weight (BW)/d, or 2.21-6.87 and 1.83-3.61 g/d, respectively in the complete data, and 43.71-96.40 and 26.77-63.70 mg/kg BW/d, or 3.06-4.06 and 1.83-2.68 g/d, respectively in the data that did not include the two studies. The intakes of the two minerals were positively correlated. Na intake (Intake) was correlated positively with apparent absorption (AA) of Na, which was also correlated with Na urinary output (Urine). In the data that did not include the two studies, Na balance (Balance) was not correlated significantly with either Na Intake (r2=0.005) or AA of Na (r2=0.006). However, analysis of all the data showed a significant correlation between Na Balance and both Na Intake (r2=0.361) and AA of Na (r2=0.360). In the complete data, the mean value and upper and lower limits of the 95% confidence interval for the regression equation between Intake and Balance for Na, when balance was equal to zero (i.e mean, upper and lower limits), were 55.824, 60.787 and 50.862 mg/ kg BW/d, respectively. K Intake was correlated positively with AA of K, which was also correlated with both Urine K and K Balance. There was a significant correlation between K Intake and K Balance in both the complete data (r2=0.213) and the data that did not include the two studies (r2 = 0.116). In all the cases, mean, upper and lower limits for K were 39.161, 41.782 and 36.540 mg/kg BW/d, respectively. Intakes of Na and K did not correlate with their respective AA rates (%). Within the ranges of K Intake in this study, K Balance was affected markedly by K Intake itself as well as by Na Intake. However, in the case of Na, when the data of the highest and lowest Na intake studies were excluded from the analysis, Na Balance did not correlate with Na Intake, whereas the data of all the studies showed Na Balance was affected strongly by Na Intake. The data of this study allowed the estimated average requirements (EARs) for both minerals to be derived.

Balance of magnesium positively correlates with that of calcium.

BACKGROUND AND OBJECTIVE: In a prior study, we showed no significant relationship between intake and balance of magnesium (Mg). Subsequent further investigation disclosed that intakes of both Ca and P were positively correlated with their respective balances, whereas intake of Mg did not show any significant correlation with Mg balance. In this paper, we show positive correlations between intake of Mg and balances of both Ca and P. METHODS AND RESULTS: Using these correlations, the mean value and upper limit of the 95% confidence interval (from the regression equation between Mg intake and either the balances of Ca or that of P, when each balance is equal to zero) were 4.584 and 4.802 (against Ca balance), 4.554 and 4.785 (against P balance) mg/kg BW/d, respectively. Balances of Mg and Ca correlated with each other.

Negative balance of calcium and magnesium under relatively low sodium intake in humans.

The balance of minerals (sodium [Na], potassium [K], calcium [Ca], and magnesium [Mg]) was measured in six female students for 10 d while under a relatively low Na intake (100 mmol/d or 2.2 g/d) with receiving adequate Ca (20 mmol/d or 800 mg/d) and Mg (12 mmol/d or 280 mg/d). Both the plasma renin activity (PRA) and aldosterone level were above the reference ranges throughout the experiment, which implied that the subjects were Na deficient. However, the urine Na excretion was about the same as that ingested, while there was no substantial reduction of sweat Na concentration observed during moderate physical exercise (13.2+/-2.6 mmol/L) (mean+/-SD). On the other hand, the urine Ca and Mg levels were high, but the apparent absorption of Ca and Mg was moderate (21 +/- 5%, 34 +/- 4%, respectively), which resulted in a negative balance of these two elements. It seems that the stored Na in the bone is eluted so as to compensate for the low dietary Na intake, while any excess Ca and Mg also inevitably flows into the blood stream with Na, which inhibited the intestinal absorption of both Ca and Mg and accelerates their excretion in urine.

Diurnal variations in human urinary excretion of nicotinamide catabolites: effects of stress on the metabolism of nicotinamide.

BACKGROUND: More than 500 enzymes need niacin coenzymes. Therefore, elucidation of the control mechanisms of coenzyme metabolism is fundamentally important. OBJECTIVE: NAD(+) is involved in ATP production. Because energy expenditure is generally higher during the day than at night, we investigated whether the metabolism of nicotinamide changes at various times of day and whether stress affects nicotinamide metabolism. DESIGN: Twelve women were housed in the same facility and followed the same schedule for activities of daily living for 12 d. Urinary outputs were collected during 5 specific periods to investigate diurnal variations in nicotinamide metabolism. The effects of cold exposure (physical stress), having to perform arithmetic calculations (mental stress), and dark exposure (emotional stress) on nicotinamide metabolism were investigated. RESULTS: A diurnal variation in the nicotinamide metabolites N(1)-methylnicotinamide, N(1)-methyl-2-pyridone-5-carboxamide, and N(1)-methyl-4-pyridone-3-carboxamide was observed. Of the stresses studied, cold exposure significantly increased the urinary excretory outputs of the nicotinamide metabolites. CONCLUSIONS: Diurnal variations in nicotinamide metabolism were found in these women. The biosynthesis of nicotinamide from tryptophan seemed to be increased by cold exposure.

Effects of stress on the urinary excretory pattern of niacin catabolites, the most reliable index of niacin status, in humans.

Urinary output of water-soluble vitamins has been used as an indices for vitamin nutrition. It has been pointed out that the coefficient variance of these values is high, especially for niacin catabolites. Thus, we investigated what kinds of stress affect the catabolism using female subjects. The effects of cold exposure (as a typical physical stress), calculation exercise (a typical mental stress) and dark exposure (a typical emotional stress) on the metabolism of niacin were investigated. Of the stresses, cold exposure significantly increased urinary excretory output of the niacin metabolites. The biosynthesis of nicotinamide from Trp seemed to be increased by cold exposure.