Nicotinamide mononucleotide supplementation enhances aerobic capacity in amateur runners: a randomized, double-blind study.

BACKGROUND: Recent studies in rodents indicate that a combination of exercise training and supplementation with nicotinamide adenine dinucleotide (NAD+) precursors has synergistic effects. However, there are currently no human clinical trials analyzing this. OBJECTIVE: This study investigates the effects of a combination of exercise training and supplementation with nicotinamide mononucleotide (NMN), the immediate precursor of NAD+, on cardiovascular fitness in healthy amateur runners. METHODS: A six-week randomized, double-blind, placebo-controlled, four-arm clinical trial including 48 young and middle-aged recreationally trained runners of the Guangzhou Pearl River running team was conducted. The participants were randomized into four groups: the low dosage group (300 mg/day NMN), the medium dosage group (600 mg/day NMN), the high dosage group (1200 mg/day NMN), and the control group (placebo). Each group consisted of ten male participants and two female participants. Each training session was 40-60 min, and the runners trained 5-6 times each week. Cardiopulmonary exercise testing was performed at baseline and after the intervention, at 6 weeks, to assess the aerobic capacity of the runners. RESULTS: Analysis of covariance of the change from baseline over the 6 week treatment showed that the oxygen uptake (VO2), percentages of maximum oxygen uptake (VO2max), power at first ventilatory threshold, and power at second ventilatory threshold increased to a higher degree in the medium and high dosage groups compared with the control group. However, there was no difference in VO2max, O2-pulse, VO2 related to work rate, and peak power after the 6 week treatment from baseline in any of these groups. CONCLUSION: NMN increases the aerobic capacity of humans during exercise training, and the improvement is likely the result of enhanced O2 utilization of the skeletal muscle. TRIAL REGISTRATION NUMBER: ChiCTR2000035138 .

Haemocyte apoptosis of the tiger shrimp Penaeus monodon exposed to cadmium.

This study investigated the effect of ambient Cadmium (Cd) on haemocyte apoptosis of the shrimp, Penaeus monodon. Cellular response was determined in Cd-exposed (0, 0.05, 0.5 and 5 mg L(-1)) shrimp. Results showed that 0.05 mg L(-1) Cd(2+) had no significant effect on the haemocyte parameters during the 48 h exposure. Cadmium at doses of 0.5 and 5 mg L(-1) depressed the total haemocyte count (THC), and increased reactive oxygen species (ROS) production and apoptosis ratio in haemocytes. Esterase activity increased in shrimp exposed to 0.5 mg L(-1) Cd(2+) for 6 h, and decreased to the initial level later. Depressed esterase activity could be observed in shrimp after 24 and 48 h exposure to 5 mg L(-1) Cd(2+). These results demonstrated that Cd(2+) modified esterase activity and induced ROS generation, which led to haemocyte apoptosis and THC reduction. Oxidative stress is one of the induction mechanisms for Cd-caused apoptosis of shrimp haemocytes.

Measurement of intracellular nitric oxide (NO) production in shrimp haemocytes by flow cytometry.

A flow cytometric method to measure the production of intracellular nitric oxide (NO) was adapted for use with shrimp haemocytes. We applied fluorescent probe 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate (DAF-FM DA) for NO detection in haemocytes from the tiger shrimp Penaeus monodon, and used flow cytometry to quantify fluorescence intensity in individual haemocyte. The optimized protocol for intracellular NO analysis consists to incubate haemocytes with DAF-FM DA at 10 µM for 60 min to determine the mean fluorescence intensity. Result showed that NO was also produced in the untreated shrimp haemocytes. NO level in granular cells and semigranular cells were much higher than that in hyaline cells. Defined by different characteristic of NO content, three subsets of haemocytes were observed. Zymosan A at dose of 10 or 100 particles per haemocyte triggered higher DAF-FM fluorescence intensity in granular and semigranular cells, than PMA that had no significant impact on all three cell types. These results indicate that granular and semigranular cells are the primary cells for NO generation. Cytochalasin B significantly inhibited the NO level induced by zymosan A. NG-Monomethyl-L-arginine (L-NMMA) and diphenylene iodonium chloride (DPI) significantly suppressed the DAF-FM fluorescence in haemocytes, but apocynin could not modulate it, indicating that the DAF-FM fluorescence was closely related to the activity of NO-synthase pathway. The NO donor sodium nitroprusside (SNP) improved the DAF-FM fluorescence in haemocytes, while the NO scavenger C-PTIO (2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) significantly decreased the fluorescence, demonstrating that the fluorescence intensity of DAF-FM is mainly dependent on the intracellular NO level.

Changes of myogenic reactive oxygen species and interleukin-6 in contracting skeletal muscle cells.

The aim of this study was to measure changes in myotube reactive oxygen species (ROS) and the production of interleukin (IL)-6 in electrically stimulated mouse C2C12 skeletal muscle cells. After five days of differentiation, myotubes were stimulated using an electrical stimulator set at 45 V at a frequency of 5 Hz, with a pulse width of 20 ms. Acute stimulations were performed for 45, 60, 75, 90, or 120 min in each dish. ROSs were detected in the extracted cells directly using a fluorescent probe. IL-6 mRNA expression in C2C12 myotubes and IL-6 concentration in C2C12 myotube supernatants were determined using real-time PCR and ELISA, respectively. Compared with control cells, ROS generation was significantly increased at 45 min after the onset of stimulation (P < 0.01) and continued to increase, reaching a maximum at 120 min. IL-6 mRNA expression and IL-6 concentration in C2C12 cells were significantly increased after 75 min (P < 0.01) and 120 min (P < 0.05) of electrical stimulation (ES) compared with the control cells. Our data show that a specific ES intensity may modulate ROS accumulation and affect IL-6 gene expression in contracting skeletal muscle cells.

In vitro toxicity of nitrite on haemocytes of the tiger shrimp, Penaeus monodon, using flow cytometric analysis.

This study investigated the in vitro effects of nitrite on reactive oxygen species (ROS) production, NO production, esterase activity and cell apoptosis of Penaeus monodon haemocytes. Haemocytes were in vitro exposed to different dose of nitrite (0, 0.1, 0.5, 1, 5 and 10 µM). Cellular responses of nitrite-treated haemocytes were determined by flow cytometry. The results revealed that haemocytes treated by nitrite in vitro showed conspicuous time- and dose-dependent decreases in ROS and NO production as well as esterase activity. Additionally, 0.1 and 0.5 µM nitrite did not affect the apoptotic cell ratio during the 3h experimental time, while significant increases in apoptotic cells were observed after haemocyte exposure to nitrite at 1 µM for 3h, and at 5 or 10 µM for 1h. These results indicated that nitrite suppresses cellular functions, including production of ROS and NO, and activity of esterase. Cell apoptosis of haemocytes would be induced by extracellular nitrite as doses exceed 1 µM.

Physical development and lifestyle of Hong Kong secondary school students.

BACKGROUND: Objectives of the present investigation were to study the growth and development of adolescents in Hong Kong, to analyze the interrelationship between their development and lifestyle, and to provide some helpful suggestions for lifestyle modification. METHODS: A total of 404 secondary students ages 12-18 years served as subjects. Morphological measures, blood pressure, blood lipids, aerobic fitness, and body composition were tested. A self-report questionnaire was administered to assess physical activity and dietary habits. RESULTS AND CONCLUSIONS: Systolic blood pressure and diastolic blood pressure increased with age, and a gender difference was noted. Body height and body weight increased with age. Total cholesterol showed a lowering trend with age, and high-density lipoprotein had a slight rise. The percentage body fat for boys decreased with age but increased for girls. The higher percentage of overweight and obesity was closely associated with physical inactivity and inappropriate food selection such as eating snacks or food rich in fat or cholesterol. Tailor-made physical activity and nutritional education programs should be designed for adolescents, especially girls during puberty.