Comparative cytotoxicity of fumonisin B1 in two cell lines derived from normal human bronchial epithelial cells using four distinct bioassay techniques

This study focuses on the cytotoxic effects of fumonisin B₁ (FB₁) on both immortalised and immortalised and subsequently transfected normal human bronchial epithelial (NHBE) cells of human origin using four bioassays. While the MTT, Neutral Red and hexosaminidase colorimetric assays showed little difference between the toxic effects on the two related cell lines, the clonogenic assay, measuring cell survival and proliferation, indicated that FB₁ had a more toxic effect on the nontransfected cells. This kind ofin vitro approach using cells which retain many characteristics of normal cell growth and differentiation can go some way to developing evaluation models for food safety in the case of mycotoxin contamination without resorting totally to whole animal testing. Nevertheless, one or two cytotoxicity tests may be inadequate for a complete appraisal of toxic potential: rather, as wide a range of methodologies as feasible should be employed initially before meaningful conclusions may be drawn.     

A forty-five year investigation for secular changes in physical maturation

In a stable, economically- and educationally-privileged population of 180 subjects observed from birth to beyond the period of maximum growth in height, no secular changes toward larger size or earlier adolescence were observed between the earlier-born and later-born boys or girls of the Child Research Council study series. The mid-birthdate for the 45 years of data collection was January 1, 1940 for the girls and May 1, 1936 for the boys. With none of the mean differences significant at the 0.05 level of confidence, the earlier-born subjects were both slightly taller and heavier from birth and, for the girls, adolescence was slightly earlier. Forty pairs of like-sexed siblings were included in the data. Coefficients of correlation were statistically significant for birthweight and menarcheal ages for the sisters and for height and weight at the age of maximum increment of growth in height for both sexes. In 12 of the 16 pairs of sisters, the older menstruated at an earlier age than the younger.     

Comparison of body cooling methods on physiological and perceptual measures of mildly hyperthermic athletes

Hyperthermia is common among athletes and in a variety of environments. The purpose of this study was to evaluate the effectiveness of cooling methods on core body temperature, heart rate (HR), and perceptual readings in individuals after exercise. Sixteen subjects (age: 24 ± 6 years, height: 182 ± 7 cm, weight: 74.03 ± 9.17 kg, and body fat: 17.08 ± 6.23%) completed 10 exercise sessions in warm conditions (WBGT: 26.64 ± 4.71°C) followed by body cooling by 10 different methods. Cooling methods included cold water immersion (CWI), shade, Port-a-Cool? (FAN), Emergency Cold Containment System? (ECCS), Rehab. Hood? (HOOD), Game Ready Active Cooling Vest? (GRV), Nike Ice Vest? (NIV), ice buckets (IBs), and ice towels (IT). These cooling modes were compared with a control (SUN). Rectal temperature (T(re)), HR, thermal sensation, thirst sensation, and a 56-question Environmental Symptoms Questionnaire (ESQ) were used to assess physiological and perceptual data. Average T(re) after exercise across all trials was 38.73 ± 0.12°C. After 10 minutes of cooling, CWI (-0.65 ± 0.29°C), ECCS (-0.68 ± 0.24°C), and IB (-0.74 ± 0.34°C) had significantly (p < 0.006) greater decreases in T(re) compared with that in SUN (-0.42 ± 0.15°C). The HR after 10 minutes of cooling was significantly (p < 0.006) lower for CWI (82 ± 15 b·min(-1)), ECCS (87 ± 14 b·min(-1)), and IT (84 ± 15 b·min(-1)) when compared with SUN (101 ± 15 b·min(-1)). The thermal sensation between modalities was all significantly (p < 0.006) lower (CWI: 1.5 ± 0.5; Fan: 3.0 ± 1.0; ECCS: 4.5 ± 1.0; Hood: 4.5 ± 0.5; GRV: 4.0 ± 0.5; NIV: 4.5 ± 1.0; IB: 4.0 ± 1.0; IT: 3.0 ± 1.0) when compared with SUN (5.5 ± 0.5), except for Shade (5.0 ± 1.0). There were no significant differences (p > 0.006) in thirst sensation between modalities. The ESQ scores were significantly (p < 0.006) lower for CWI (1 ± 6), Fan (4 ± 5), and IT (3 ± 8) compared with that for SUN (13 ± 12). In conclusion, when athletes experience mild hyperthermia, CWI, ECCS, and IB resulted in a significantly greater decrease in T(re). These cooling strategies are recommended to decrease T(re) during a brief recovery period between exercise bouts.     

Appearance of D2O in sweat after oral and oral-intravenous rehydration in men

Intravenous (IV) rehydration is common in athletics, but its thermoregulatory benefits and ergogenicity have not been elucidated. Availability of orally ingested fluid is dependent on gastric emptying and intestinal absorption rate. Deuterium oxide (D2O) has been used to demonstrate that fluid ingested during exercise appears in sweat within 10 minutes. The purpose of this study was to determine the effect of concurrent IV rehydration on D2O appearance in sweat samples after per ora rehydration with D2O labeled fluid. We hypothesized that the combination method would not be superior to the oral method. Ten fit men (age 23 ± 4, VO2max 59.49 ± 4.09 L·min(-1)) underwent 20 hours of fluid restriction resulting in 1.95 ± 0.25% body weight loss before beginning treadmill exercise and cycling. Exercise was performed in an environmental chamber (35.6 ± 0.2° C, 35.0 ± 1.8% relative humidity) for 2 hours at 55% VO2max, and the participants exhibited a mean body weight deficit of 4.50 ± 0.04%. Thermoregulatory measures were recorded while subjects were rehydrated with oral (OR) or oral combined with intravenous (IVO) fluid traced with D2O. After 30 minutes of rehydration and 30 minutes of seated recovery, the subjects began treadmill exercise at 55-60% VO2max. Forehead sweat samples were collected 0, 5, 10, 20, and 75 minutes from the start of rehydration. The samples were analyzed for D2O via isotope ratio mass spectrometry. D2O did not appear in the sweat within 20 minutes of rehydration; however, it did appear during the subsequent exercise bout. There was no significant difference between rehydration modes. Plasma volume increases and decreased volume of orally ingested fluid did not significantly alter transit time from ingestion to appearance in excreted sweat. The IVO method does not appear to be superior to the traditional OR method of rehydration.     

Gray matter imaging in multiple sclerosis: what have we learned?

At the early onset of the 20^th century, several studies already reported that the gray matter was implicated in the histopathology of multiple sclerosis (MS). However, as white matter pathology long received predominant attention in this disease, and histological staining techniques for detecting myelin in the gray matter were suboptimal, it was not until the beginning of the 21^st century that the true extent and importance of gray matter pathology in MS was finally recognized. Gray matter damage was shown to be frequent and extensive, and more pronounced in the progressive disease phases. Several studies subsequently demonstrated that the histopathology of gray matter lesions differs from that of white matter lesions. Unfortunately, imaging of pathology in gray matter structures proved to be difficult, especially when using conventional magnetic resonance imaging (MRI) techniques. However, with the recent introduction of several more advanced MRI techniques, the detection of cortical and subcortical damage in MS has considerably improved. This has important consequences for studying the clinical correlates of gray matter damage. In this review, we provide an overview of what has been learned about imaging of gray matter damage in MS, and offer a brief perspective with regards to future developments in this field.     

Eleven days of moderate exercise and heat exposure induces acclimation without significant HSP70 and apoptosis responses of lymphocytes in college-aged males

The purpose of this study was to assess whether a lymphocyte heat shock response and altered heat tolerance to ex vivo heat shock is evident during acclimation. We aimed to use flow cytometry to assess the CD3⁺CD4⁺ T lymphocyte cell subset. We further aimed to induce acclimation using moderately stressful daily exercise-heat exposures to achieve acclimation. Eleven healthy males underwent 11 days of heat acclimation. Subjects walked for 90 min (50 ± 8% VO_2max) on a treadmill (3.5 mph, 5% grade), in an environmental chamber (33°C, 30–50% relative humidity). Rectal temperature (°C), heart rate (in beats per minute), rating of perceived exertion , thermal ratings, hydration state, and sweat rate were measured during exercise and recovery. On days 1, 4, 7, 10, and 11, peripheral blood mononuclear cells were isolated from pre- and post-exercise blood samples. Intracellular and surface HSP70 (SPA-820PE, Stressgen, Assay Designs), and annexin V (ab14085, Abcam Inc.), as a marker of early apoptosis, were measured on CD3⁺ and CD4⁺ (sc-70624, sc-70670, Santa Cruz Biotechnology) gated lymphocytes. On day 10, subjects experienced 28 h of sleep loss. Heat acclimation was verified with decreased post-exercise rectal temperature, heart rate, and increased sweat rate on day 11, versus day 1. Heat acclimation was achieved in the absence of significant changes in intracellular HSP70 mean fluorescence intensity and percent of HSP70⁺ lymphocytes during acclimation. Furthermore, there was no increased cellular heat tolerance during secondary ex vivo heat shock of the lymphocytes acquired from subjects during acclimation. There was no effect of a mild sleep loss on any variable. We conclude that our protocol successfully induced physiological acclimation without induction of cellular heat shock responses in lymphocytes and that added mild sleep loss is not sufficient to induce a heat shock response.     

Maximal power at different percentages of one repetition maximum: influence of resistance and gender

National Collegiate Athletic Association Division I athletes were tested to determine the load at which maximal mechanical output is achieved. Athletes performed power testing at 30, 40, 50, 60, and 70% of individual 1 repetition maximum (1RM) in the squat jump, bench press, and hang pull exercises. Additionally, hang pull power testing was performed using free-form (i.e., barbell) and fixed-form (i.e., Smith machine) techniques. There were differences between genders in optimal power output during the squat jump (30-40% of 1RM for men; 30-50% of 1RM for women) and bench throw (30% of 1RM for men; 30-50% of 1RM for women) exercises. There were no gender or form interactions during the hang pull exercise; maximal power output during the hang pull occurred at 30-60% of 1RM. In conclusion, these results indicate that (a) gender differences exist in the load at which maximal power output occurs during the squat jump and bench throw; and (b) although no gender or form interactions occurred during the hang pull exercise, greater power could be generated during fixed-form exercise. In general, 30% of 1RM will elicit peak power outputs for both genders and all exercises used in this study, allowing this standard percentage to be used as a starting point in order to train maximal mechanical power output capabilities in these lifts in strength trained athletes.     

Comparison of low- and high-intensity resistance exercise on lipid peroxidation: role of muscle oxygenation

The purpose of this study was to examine the effect of low- vs. high-intensity resistance exercise on lipid peroxidation. In addition, the role of muscle oxygenation on plasma malondialdehyde (MDA) concentrations was explored. Eleven experienced resistance trained male athletes (age: 20.8 +/- 1.3 years; weight: 96.2 +/- 14.4 kg; height: 182.4 +/- 7.3 cm) performed 4 sets of the squat exercise using either a low-intensity, high-volume (LI; 15 repetitions at 60% 1 repetition maximum [1RM]) or high-intensity, low-volume (HI; 4 repetitions at 90% 1RM load). Venous blood samples were obtained before the exercise (PRE), immediately following the exercise (IP), and 20 (20P) and 40 minutes (40P) postexercise. Continuous wave near-infrared spectroscopy was used to measure muscle deoxygenation in the vastus lateralis during exercise. Deoxygenated Hb/Mb change was used to determine reoxygenation rate during recovery. No difference in MDA concentrations was seen between LI and HI at any time. Significant correlations were observed between plasma MDA concentrations at IP and the half-time recovery (T1/2 recovery) of muscle reoxygenation (r = 0.45) and between T1/2 recovery and the area under the curve for MDA concentrations (r = 0.44). Results suggest that increases in MDA occur independently of exercise intensity, but tissue acidosis may have a larger influence on MDA formation.     

Responses of criterion variables to different supplemental doses of L-carnitine L-tartrate

L-carnitine L-tartrate (LCLT) supplementation beneficially affects markers of postexercise metabolic stress and muscle damage. However, to date, no study has determined the dose response of LCLT to elicit such responses. Therefore, the purpose of this study was to determine the effects of different doses of LCLT on criterion variables previously shown to be responsive to LCLT supplementation. Eight healthy men (22 +/- 3 y, 174 +/- 5 cm, 83.0 +/- 15.3 kg) were supplemented with 0 g, 1 g, and 2 g of LCLT for 3 weeks and then performed a bout of resistance exercise (5 sets of 15-20 repetition maximum with a 2-min rest between sets) with associated blood draws. This procedure was performed in a balanced, randomized, repeated measures design. Serum carnitine concentrations increased (p < or = 0.05) following the 1 g and 2 g doses, with the 2-g dose providing the highest carnitine concentrations. The 1- and 2-g doses reduced postexercise serum hypoxanthine, serum xanthine oxidase, serum myoglobin, and perceived muscle soreness. In conclusion, both the 1- and 2-g doses were effective in mediating various markers of metabolic stress and of muscle soreness. Use of LCLT appears to attenuate metabolic stress and the hypoxic chain of events leading to muscle damage after exercise.