Plasma ammonia concentrations and the slow component of oxygen uptake kinetics during cycle ergometry.

The purposes of this study were to 1) compare the patterns of responses for plasma ammonia concentration ([NH3]) during moderate- vs. heavy-intensity cycle ergometry, and 2) examine the relationship between the V O2 slow component (V O 2SC) and plasma [NH3]. Thirteen healthy, untrained men (mean +/- SEM age = 24.8 +/- 0.6 years) performed a total of eight constant power output exercises (7 minutes in duration) at two different intensities (moderate, 60% gas exchange threshold [GET] = 60% of the gas exchange threshold; and heavy, Delta 50% = 50% of the difference between GET and V O2 max). Blood was collected from an antecubital vein before the exercise, during the last 3 minutes of the 6-minute warm-up, and during each minute of the 7-minute constant power output workbout. The time course of changes in plasma [NH3] and V O2 during the two constant power output exercise intensities were assessed separately using 2 (intensity) x 7 (time) repeated-measures analyses of variance. For 60% GET, there were no significant differences in the mean normalized plasma [NH3] during the 7-minute workbout. For Delta 50%, there was a significant increase in the mean normalized plasma [NH3] during the 7-minute workbout. These findings suggest a potential relationship between exercise-induced hyperammonemia and the V O 2SC during heavy-intensity exercise.

Human osteogenic protein-1 induces osteogenic differentiation of adipose-derived stem cells harvested from mice.

OBJECTIVE: Osteogenic protein-1 (OP-1) has been shown to stimulate undifferentiated cells to produce mineralized tissue. Adipose tissue is a rich source of undifferentiated cells for tissue engineering purposes. The purpose of this study was to investigate the effect of OP-1 on osteogenic differentiation of adipose-derived stem cells and the production of bony tissue in vitro. DESIGN: Adipose-derived stem cells (ADSCs) were isolated from inguinal fat pads of adult mice. Following cell expansion the cells were plated in 8-well chambered slides. The cells received one of four treatments: Group 1 cells were maintained in control medium, Group 2 cells were cultured in a common osteogenic medium, Group 3 cells were cultured in osteogenic medium supplemented with 250ng/mL of OP-1, and Group 4 cells were cultured with 250ng/mL of OP-1 added to control medium. Osteogenic differentiation of ADSCs was determined by estimating the number and size of mineralized nodules, and the amount of extracellular osteopontin secreted into cell culture medium. Mineralized nodule production was assessed at day 21 with von Kossa staining. Extracellular osteopontin release was measured after 8 and 21 days by enzyme-linked immunosorbant assay (ELISA). ANOVA/Tukey tests were used to identify differences among the four treatment groups for mineralized nodule production and osteopontin release (p0.05), which were significantly higher than the group incubated in cell growth medium only (p0.05). Linear regression analysis demonstrated a linear relationship was present between the presence of calcified nodules and the amount of osteopontin released (p

Speed of tooth movement is related to stress and IL-1 gene polymorphisms.

INTRODUCTION: The variables affecting speed of tooth movement are unquantified. In particular, the effects of stress and human biological variations are unknown. Therefore, our objectives in this study were to determine relationships between (1) stress and velocity of tooth translation (v(t)), and (2) interleukin-1 (IL-1) gene cluster polymorphisms, IL-1beta and IL-1 receptor antagonist (IL-1RA) in gingival crevicular fluid (GCF), and v(t). METHODS: Ten subjects had their maxillary first premolars extracted and cheek wipe samples genotyped. In each subject, a maxillary canine received 26 kPa and the other received 13 or 52 kPa of stress. GCF samples and tooth movements were measured at 9 or 10 visits over 84 days. RESULTS: Mean v(t) for canines retracted by 13, 26, and 52 kPa were 0.054, 0.072, and 0.064 mm per day, respectively. Faster v(t) was shown from 26 kPa than 13 kPa (P = .015) and 52 kPa (P = .030), with higher IL-1beta/IL-1RA in GCF at experimental relative to control sites, and in subjects with homozygosity for allele 1 (A1,A1) compared with at least 1 copy of A2 (A2+) at IL-1RN(VNTR(86 bp)) (P = .032), and with A2+ compared with A1,A1 at IL-1B(+3954) (P = .051). CONCLUSIONS: Stress, IL-1beta/IL-1RA in GCF, and IL-1 gene cluster polymorphisms are related to v(t).

Tooth movement and cytokines in gingival crevicular fluid and whole blood in growing and adult subjects.

INTRODUCTION: Tooth movement has been studied largely with respect to the force required for tipping when pressure distribution varies along the length of the periodontal ligament. But important factors for effective canine translation include the nature and magnitude of applied stress and the patient's cell biology. The purpose of this research was to test 3 hypotheses: (1) the velocity of tooth translation (v(t)) is related to applied stress and growth status, (2) a threshold of stress accounts for the lag phase, and (3) v(t) is correlated with the ratio (AI) of 2 cytokines (IL-1beta, IL-1RA) measured in gingival crevicular fluid (GCF) and stimulated whole blood (SWB). METHODS: Continuous maxillary canine retraction stresses of 13 kPa and 4, 26, or 52 kPa were applied bilaterally in 6 growing and 4 adult subjects for 84 days. Dental models and GCF samples were collected at 1- to 14-day intervals. Cytokines were measured in GCF and SWB cell cultures. RESULTS: V(t) was positively related to stress and was higher in growing subjects (P = .001). It was also related to AI(GCF) in growers (R2= 0.56) and nongrowers (R2= 0.72). Canines moved with 52 kPa showed a lag phase, and postlag phase AI(GCF) was twice that of lag phase AI(GCF). Mean v(t) and associated AI(GCF) during the postlag phase were nearly double the values for canines moved with 13 and 26 kPa. SWB production of cytokines was dose-dependent. For growing subjects, SWB IL-1RA was correlated with v(t) (R = 0.70-0.72), and AI(SWB) and IL-1beta concentrations were correlated with AI(GCF) (R = 0.73-0.78). CONCLUSIONS: V(t) varied with growth status and stresses < or = 52 kPa; stresses of < 52 kPa showed no lag phase; and equivalent stresses yielded subject-dependent differences in v(t), which correlated with cytokines in GCF and SWB.