Novel modulators for body weight changes induced by fasting and re-feeding in mice

Catch-up weight gain after malnutrition is a risk factor for metabolic syndrome. Here we show that social isolation enhanced fasting-induced weight loss and suppressed weight gain induced by re-feeding for 6 days following a 24-h fast in prepubertal wild-type mice. These effects of social isolation on weight gain were not associated with significant changes in daily average food consumption. Under the same housing condition, genetic deletion of β-endorphin reduced the fasting-induced weight loss and enhanced the re-feeding-induced weight gain in prepubertal mice. These effects of social isolation or genetic deletion of β-endorphin on these weight changes were attenuated and reversed in postpubertal mice. Moreover, genetic deletion of β-endorphin attenuated these effects of social isolation on the catch-up weight gain in prepubertal mice and reversed them in postpubertal mice. Thus, social isolation, endogenous β-endorphin, and age can be novel modulators for body weight changes induced by fasting and re-feeding in mice.     

Urinary cytokines for assessing inflammation in HIV-associated wasting

The relationship between cytokines and HIV-related weight loss has not been well established. Unlike most cytokines that are secreted in a paracrine manner, IL-6, sTNFR-II, and IL-1ra are readily detected in the systemic circulation and serve as markers of the inflammatory response. Twenty-four-hour urine concentrations of these proteins are believed to provide an integrative assessment of their systemic levels over the preceding hours. We sought to determine whether spot measurements of IL-6, sTNFR-II, and IL-1ra could be related to subsequent 24 h concentrations and prior weight loss. Eighteen subjects with severe wasting (average BMI=18+/-3 kg/m2with 19+/-13 kg of weight loss) and six HIV-negative healthy subjects were tested. Compared to values in controls, 24-h urinary concentrations of the three proteins adjusted for creatinine excreted were elevated in 44%, 89%, and 72% of patients, respectively. Twenty-four-hour concentrations were highly correlated with the spot concentrations (r=0.80, 0.87, 0.84, respectively, P<0.001). IL-1ra concentrations (24 h and spot) were correlated with weight loss in the previous 6 months, lifetime rate of weight loss and the 6 month rate of weight loss (spot: r=0.66, 0.73, 0.68, respectively, P< or =0.001). These data suggest that spot urinary collections can be used to estimate 24 h excretion rates. This strategy may be useful in assessing the inflammatory response in HIV-associated wasting.     

Acid aspiration increases sensitivity to increased ambient oxygen concentrations

Previously we have demonstrated that prolonged exposure to 100% ambient oxygen leads to a marked loss in functional lung volume and lung compliance, hypoxemia, and surfactant system abnormalities similar to acute respiratory distress syndrome (ARDS). However, 50% oxygen administration is believed to be safe in most clinical settings. In the present study, we have evaluated the effects of a 24-h exposure to 50% oxygen in rabbits immediately following experimental gastric acid aspiration. Mild hypoxemia, but no changes in mortality, lung volume, lung compliance, surfactant metabolism, or edema formation occurred after 24 h of normoxia postacid aspiration. Conversely, a relatively short (24-h) exposure to 50% oxygen after acid aspiration results in increased pulmonary edema, physical signs of respiratory distress, and mortality, as well as decreased arterial oxygenation, lung volume, lung compliance, and type II alveolar cell surfactant synthesis. These results suggest that acid aspiration alters the "set point" for oxygen toxicity, possibly by "priming" cells through activation of inflammatory pathways. This pathogenic mechanism may contribute to the progression of aspiration pneumonia to ARDS.     

The mind your health project: A randomized controlled trial of an innovative behavioral treatment for obesity

Objective: To determine whether acceptance‐based behavioral treatment (ABT) would result in greater weight loss than standard behavioral treatment (SBT), and whether treatment effects were moderated by interventionist expertise or participants' susceptibility to eating cues. Recent research suggests that poor long‐term weight‐control outcomes are due to lapses in adherence to weight‐control behaviors and that adherence might be improved by enhancing SBT with acceptance‐based behavioral strategies. Design and Methods : Overweight participants (n = 128) were randomly assigned to 40 weeks of SBT or ABT. Results : Both groups produced significant weight loss, and when administered by experts, weight loss was significantly higher in ABT than SBT at post‐treatment (13.17% vs. 7.54%) and 6‐month follow‐up (10.98% vs. 4.83%). Moreover, 64% of those receiving ABT from experts (vs. 46% for SBT) maintained at least a 10% weight loss by follow‐up. Moderation analyses revealed a powerful advantage, at follow‐up, of ABT over SBT in those potentially more susceptible to eating cues. For participants with greater baseline depression symptomology, weight loss at follow‐up was 11.18% in ABT versus 4.63% in SBT; other comparisons were 10.51% versus 6.00% (emotional eating), 8.29% versus 6.35% (disinhibition), and 9.70% versus 4.46% (responsivity to food cues). Mediation analyses produced partial support for theorized food‐related psychological acceptance as a mechanism of action. Conclusions : Results offer strong support for the incorporation of acceptance‐based skills into behavioral weight loss treatments, particularly among those with greater levels of depression, responsivity to the food environment, disinhibition, and emotional eating, and especially when interventions are provided by weight‐control experts.     

Increased circadian prolactin release is blunted after body weight loss in obese premenopausal women

We recently showed that prolactin (PRL) release is considerably enhanced in obese women in proportion to the size of their visceral fat mass. PRL release is inhibited by dopamine 2 receptor (D2R) activation, and dietary restriction/weight loss are associated with increased dopaminergic signaling in animals. Therefore, we hypothesized that enhanced PRL release in obese humans would be reversed by weight loss. To evaluate this postulate, we measured 24-h plasma PRL concentrations at 10-min intervals in 11 obese premenopausal women (BMI 33.3 +/- 0.7 kg/m2) before and after weight loss (50% reduction of overweight/15% absolute weight loss, using a very low-calorie diet) in the follicular phase of their menstrual cycle. The 24-h PRL concentration profiles were analyzed by a peak detection program (Cluster) and a wave form-independent deconvolution technique (Pulse). Spontaneous 24-h PRL secretion was significantly reduced in obese women [mean daily release, before 128 +/- 24 vs. after weight loss 110 +/- 17 microg/liter distribution volume (Vdl)(-1) x 24 h, P = 0.05]. Body weight loss particularly blunted PRL secretory burst mass (Pulse area, before 230 +/- 28 vs. after weight loss 221 +/- 31 microg/Vdl(-1) x 24 h, P = 0.03), whereas burst frequency was unaffected (no. of pulses, before 11 +/- 1 vs. after weight loss 12 +/- 1 n/24 h, P = 0.69). Thus elevated PRL secretion rate in obese women is significantly reduced after loss of 50% of overweight. We speculate that amelioration of deficit D2R-mediated neurotransmission and/or diminutions of circulating leptin/estrogen levels might be involved in the physiology of this phenomenon.     

Weight loss, diet composition and cardiovascular risk

PURPOSE OF REVIEW: Low-fat high-carbohydrate diets for weight loss have been challenged by alternative dietary approaches such as low-carbohydrate, high-protein or low glycaemic index. This review summarizes recent evidence on short-term metabolic effects and long-term adherence. RECENT FINDINGS: Very low carbohydrate freely fed diets containing less than 60 g carbohydrate per day appear more effective at inducing weight loss over 6 months than low-fat kilojoule-controlled diets although long-term compliance to both are equally poor. The LDL-cholesterol level did not increase in most studies and triglyceride levels fell dramatically in all studies, although none of the studies measured lipids in energy balance. Direct comparisons of the long-term efficacy and safety of low-fat and low-carbohydrate ad libitum diets are needed. High-protein diets with moderate levels of both fat and carbohydrate and diets low in glycaemic load are emerging dietary strategies, with medium-term benefits having been demonstrated in individuals with insulin resistance. Diets low in glycaemic index require larger studies to establish their efficacy for weight loss and cardiovascular disease risk reduction. SUMMARY: A variety of dietary approaches to achieve weight loss are consistent with metabolic improvements in cardiovascular risk in the short term. Long-term efficacy may depend on the intensity of education and frequency of follow-up more than the dietary composition per se.     

Polysomnographic sleep, growth hormone insulin-like growth factor-I axis, leptin, and weight loss

Short sleep appears to be strongly associated with obesity and altered metabolic function, and sleep and growth hormone (GH) secretion seems interlinked. In obesity, both the GH-insulin-like-growth-factor-I (GH-IGF-I) axis and sleep have been reported to be abnormal, however, no studies have investigated sleep in relation to the GH-IGF-I axis and weight loss in obese subjects. In this study polygraphic sleep recordings, 24-h GH release, 24-h leptin levels, free-IGF-I, total-IGF-I, IGF-binding protein-3 (IGFBP-3), acid-labile subunit (ALS), cortisol and insulin sensitivity were determined in six severely obese subjects (BMI: 41+/-1 kg/m(2), 32+/-2 years of age), cross-sectional at baseline, and longitudinal after a dramatically diet-induced weight loss (36+/-7 kg). Ten age- and gender-matched nonobese subjects served as controls. Sleep duration (360+/-17 vs. 448+/-15 min/night; P<0.01), 24-h GH (55+/-9 vs. 344+/-55 mU/l.24 h; P<0.01), free-IGF-I (2.3+/-0.42 vs. 5.7+/-1.2 microg/l; P<0.01), and total-IGF-I (186+/-21 vs. 301+/-18 microg/l; P<0.01) were significantly decreased and 24-h leptin levels were increased (35+/-5 vs. 12+/-3 microg/l; P<0.01) in obese subjects at pre-weight loss compared with nonobese subjects After diet-induced weight loss the differences in GH, free IGF-I, and leptin were no longer present between previously obese and nonobese subjects, whereas a significant difference in sleep duration and total IGF-I levels persisted. Rapid eye movement (REM) sleep, non-REM sleep, IGFBP-3, ALS, and cortisol levels were similar in obese and nonobese subjects. Sleep duration, 24-h GH, and IGF-I levels were decreased and 24-h leptin levels were increased in obese subjects. We conclude that hyposomatotropism and hyperleptinemia in obesity are transient phenomena reversible with weight loss, whereas short sleep seems to persist after weight has been reduced dramatically.     

Vegetarian and Weight‐Loss Diets among Young Adults

Objective: Young adults frequently experiment with vegetarian and weight‐loss diets. Comparisons of their experiences on these two different diets may help in the development of approaches to improve long‐term adherence to weight‐loss regimens. In the current study vegetarian and weight‐loss diets were compared on how long and how strictly they were followed, and reasons why they were initiated and discontinued. Research Methods and Procedures: From 428 college students surveyed, four groups were delineated: 1) 59 participants had been following a vegetarian diet but not a weight‐loss diet (Vegetarian), 2) 117 participants had tried a weight‐loss diet but not a vegetarian diet (Weight Loss), 3) 133 participants had followed both a vegetarian and a weight‐loss diet (Both), and 4) 119 participants had not tried either diet (Neither). Results: Differences were examined by comparing the Vegetarian and Weight‐Loss groups as well as by comparing the two diets within the Both group. Duration of the vegetarian diet was much greater than the weight‐loss diet; most participants in the Vegetarian group (62%) remained on their diet for more than 1 year, whereas the majority of the Weight‐Loss participants (61%) followed their diet for 1 to 3 months. Similar results were found when comparing the two diets within the Both group. How strictly the two diets were followed, however, did not differ. Analyses revealed that reasons for discontinuing a diet varied; participants were more likely to cite boredom as a reason for discontinuing a weight‐loss diet than a vegetarian diet (53% vs. 5% between groups and 30% vs. 10% within the Both group). Discussion: The longer duration of the vegetarian diet relative to the weight‐loss diet warrants further investigation. Results could possibly be applied to behavioral weight‐loss treatment to improve long‐term maintenance.     

The intestinal peptide transporter PEPT1 is involved in food intake regulation in mice fed a high-protein diet

High-protein diets are effective in achieving weight loss which is mainly explained by increased satiety and thermogenic effects. Recent studies suggest that the effects of protein-rich diets on satiety could be mediated by amino acids like leucine or arginine. Although high-protein diets require increased intestinal amino acid absorption, amino acid and peptide absorption has not yet been considered to contribute to satiety effects. We here demonstrate a novel finding that links intestinal peptide transport processes to food intake, but only when a protein-rich diet is provided. When mice lacking the intestinal peptide transporter PEPT1 were fed diets containing 8 or 21 energy% of protein, no differences in food intake and weight gain were observed. However, upon feeding a high-protein (45 energy%) diet, Pept1(-/-) mice reduced food intake much more pronounced than control animals. Although there was a regain in food consumption after a few days, no weight gain was observed which was associated with a reduced intestinal energy assimilation and increased fecal energy losses. Pept1(-/-) mice on high-protein diet displayed markedly reduced plasma leptin levels during the period of very low food intake, suggesting a failure of leptin signaling to increase energy intake. This together with an almost two-fold elevated plasma arginine level in Pept1(-/-) but not wildtype mice, suggests that a cross-talk of arginine with leptin signaling in brain, as described previously, could cause these striking effects on food intake.     

Effects of sleep restriction on glucose control and insulin secretion during diet-induced weight loss

Insufficient sleep is associated with changes in glucose tolerance, insulin secretion, and insulin action. Despite widespread use of weight-loss diets for metabolic risk reduction, the effects of insufficient sleep on glucose regulation in overweight dieters are not known. To examine the consequences of recurrent sleep restriction on 24-h blood glucose control during diet-induced weight loss, 10 overweight and obese adults (3F/7M; mean (s.d.) age 41 (5) years; BMI 27.4 (2.0) kg/m(2)) completed two 14-day treatments with hypocaloric diet and 8.5- or 5.5-h nighttime sleep opportunity in random order 7 (3) months apart. Oral and intravenous glucose tolerance test (IVGTT) data, fasting lipids and free fatty acids (FFA), 24-h blood glucose, insulin, C-peptide, and counter-regulatory hormone measurements were collected after each treatment. Participants had comparable weight loss (1.0 (0.3) BMI units) during each treatment. Bedtime restriction reduced sleep by 131 (30) min/day. Recurrent sleep curtailment decreased 24-h serum insulin concentrations (i.e., enhanced 24-h insulin economy) without changes in oral glucose tolerance and 24-h glucose control. This was accompanied by a decline in fasting blood glucose, increased fasting FFA, which suppressed normally following glucose ingestion, and lower total and low-density lipoprotein cholesterol concentrations. Sleep-loss-related changes in counter-regulatory hormone secretion during the IVGTT limited the utility of the test in this study. In conclusion, sleep restriction enhanced 24-h insulin economy without compromising glucose homeostasis in overweight individuals placed on a balanced hypocaloric diet. The changes in fasting blood glucose, insulin, lipid and FFA concentrations in sleep-restricted dieters resembled the pattern of human metabolic adaptation to reduced carbohydrate availability.     

Physical Activity and Long-Term Maintenance of Weight Loss

To examine the effect of exercise on the long-term maintenance of weight loss, two types of literature were reviewed - correlational studies of predictors of long-term weight loss, and randomized trials comparing diet, exercise, and the combination of diet plus exercise. Both literatures were striking in the consistency with which activity emerged as a determinant of long-term maintenance of weight loss. The benefits of exercise for long-term weight maintenance were observed with different types of populations, diets, and exercise interventions. Several possible explanations for these positive effects of diet plus exercise are presented, and suggestions made for future research on ways to maximize the benefit of this approach to weight control. Since adherence to exercise may ultimately prove to be the cornerstone for long-term weight maintenance, studying ways to improve exercise adherence is recommended.     

The developmental stage of chicken embryos modulates the impact of in ovo olfactory stimulation on food preferences

Like mammals, bird embryos are capable of chemosensory learning, but the ontogeny of their feeding preferences has not been examined. We tested if the timing of stimulation in chicken embryos modulates the impact of in ovo olfactory stimulation on later food preferences. We exposed chicken embryos to an olfactory stimulus for a 4-day period in the middle or toward the end of the incubation period. The chicks were tested for their preference between foods with and without the olfactory stimulus in 3-min choice tests and on a 24-h time scale. Regardless of the type of food (familiar or novel) or the duration of the test, the control chicks not exposed to the olfactory stimulus consistently showed significant preferences for non-odorized foods. Chicks that were exposed in ovo to the olfactory stimulus did not show a preference for odorized or non-odorized foods. Only those chicks that were exposed to the olfactory stimulus toward the end of the incubation period differed from the controls and incorporated a higher proportion of odorized food into their diets on a 24-h time scale. This result indicates that olfactory stimulation at the end of embryonic development has a stronger impact on later feeding preferences. Our findings contribute to the growing pool of recent data appreciating the impact of olfactory signals on behavior regulation in avian species.     

Tannins and saponin: Interaction in herbivore diets

Mice allowed to choose between diets containing tannin or saponin did not experience food intake depression, weight loss or high faeces weight to food weight ratios. Diets containing tannin produced all these effects and saponin diets resulted in weight losses and high faeces to food ratios. Mice provided with diets containing both tannin and saponin in predetermined proportions experienced weight losses similar to, or greater than, those of mice fed diets containing either toxin alone. Urinary glucuronide production by mice provided with a choice of tannin and saponin diets was less than that of mice feeding on diets containing either tannin or saponin alone. Simultaneous consumption of tannin and saponin (in the right proportions) may promote chemical interactions that inhibit the toxins' absorption from the intestinal tract. This type of interaction is likely to have influenced the evolution of herbivore feeding behaviour.     

Sibutramine: A Novel New Agent for Obesity Treatment

Sibutramine is a novel new pharmacologic agent which is a specific reuptake inhibitor for norepinephrine and serotonin. Preclinical data show that sibutramine and its two metabolites reduce food intake of animals eating either high or low carbohydrate diets and of obese Zucker rats. An 8-week clinical trial showed a dose-dependent decrease on body weight. Sibutramine, 5 and 20 mg/day, produced a dose-related weight loss in obese subjects compared to placebo in an 8-week trial. In doses varying from 1 to 30 mg, sibutramine also produced a dose-dependent decrease in weight in the healthy obese population when used in 6-,8-,12–24- and 52-week trials. Although the majority of the weight loss occurred during the first 12 weeks of treatment, weight loss had not plateaued in by 24 weeks in the higher doses. Side effects were mild. This drug shows promise as an antiobesity drug.     

Clinical Studies with Dexfenfluramine: From Past to Future

d Fenfluramine (dF) (15 mg twice daily) has been studied in controlled trials in human obesity. It has been shown to increase adherence to weight lowering programs, to double the number of patients losing 10 kg or more when compared with a fairly efficient placebo plus dietary counselling, and to prevent weight regain when continued over a 1 year period. Weight loss after 1 month and 4 months is likely to predict subsequent outcome. Also, significant improvement in metabolic risk factors and blood pressure were clearly demonstrated, even more markedly in some obesity-associated diseases, when body weight is maintained at a lower level. Even moderate but sustained weight loss of some 10 % of starting weight or less has been confirmed to be of medical value. Tolerance and safety of dF can be considered acceptable, even if longer term follow-up is clearly needed. These studies support the concept that long-term pharmacotherapy with this serotoninergic drug might help achieve better outcome in the management of many obese patients, particularly in preventing relapse. The long-term managerial strategies to be developed for each patient might thus include dF together with dietary advice, behavioral modification and physical exercise, either simultaneously or sequentially.     

Validation and Assessment of Three Methods to Estimate 24-h Urinary Sodium Excretion from Spot Urine Samples in Chinese Adults

24-h urinary sodium excretion is the gold standard for evaluating dietary sodium intake, but it is often not feasible in large epidemiological studies due to high participant burden and cost. Three methods—Kawasaki, INTERSALT, and Tanaka—have been proposed to estimate 24-h urinary sodium excretion from a spot urine sample, but these methods have not been validated in the general Chinese population. This aim of this study was to assess the validity of three methods for estimating 24-h urinary sodium excretion using spot urine samples against measured 24-h urinary sodium excretion in a Chinese sample population. Data are from a substudy of the Prospective Urban Rural Epidemiology (PURE) study that enrolled 120 participants aged 35 to 70 years and collected their morning fasting urine and 24-h urine specimens. Bias calculations (estimated values minus measured values) and Bland-Altman plots were used to assess the validity of the three estimation methods. 116 participants were included in the final analysis. Mean bias for the Kawasaki method was -740 mg/day (95% CI: -1219, 262 mg/day), and was the lowest among the three methods. Mean bias for the Tanaka method was -2305 mg/day (95% CI: -2735, 1875 mg/day). Mean bias for the INTERSALT method was -2797 mg/day (95% CI: -3245, 2349 mg/day), and was the highest of the three methods. Bland-Altman plots indicated that all three methods underestimated 24-h urinary sodium excretion. The Kawasaki, INTERSALT and Tanaka methods for estimation of 24-h urinary sodium excretion using spot urines all underestimated true 24-h urinary sodium excretion in this sample of Chinese adults. Among the three methods, the Kawasaki method was least biased, but was still relatively inaccurate. A more accurate method is needed to estimate the 24-h urinary sodium excretion from spot urine for assessment of dietary sodium intake in China.     

The effect of dietary protein on the excretion of alpha2u, the sex-dependent protein of the adult male rat.

Adult male rats were maintained on normal (20% casein), protein-free (0% casein), high protein (50% casein), decicient protein (20% zein), and a supplemented, deficient protein (20% zein plus L-lysine and L-tryptophan) diets. Rats on a protein-free diet excreted approximately 1 mg alpha2u/24 h compared with a normal of 10-15 mg/24 h. Depleted rats placed on a 20% casein diet showed a rapid restoration of the normal alpha2u excretion as well as total urinary proteins. Accumulation of alpha2u in the blood serum was measured in nep-rectomized rats. Rats on a 0% casein diet accumulated only 30% of the alpha2u compared to normals. On a 50% casein diet, rats excreted 30-50 mg alpha2u/24 h. However, the accumulation was normal in the serum of nephrectomized rats. A high protein diet did not stimulate alpha2u synthesis but probably increased the renal loss of all urinary proteins. The excretion of alpha2u on a zein diet was reduced to the same degree as with the protein-free diet. Supplementation with lysine and tryptophan restored the capacity to eliminate alpha21 to near normal levels. Accumulation of alpha2u in the serum of nephrectomized rats kept on the zein diets showed that the effect to suppress the synthesis of the ahpha2u. Supplementation restored the biosynthesis of alpha2u. We conclude that the effect of dietary protein on the excretion of urinary proteins in the adult male rat is caused in large part by an influence on the hepatic biosynthesis of alphay2u. The biosynthesis of this protein, which represents approximately 30% of the total urinary proteins, is dependent on an adequate supply of dietary protein.     

Pramlintide treatment reduces 24-h caloric intake and meal sizes and improves control of eating in obese subjects: a 6-wk translational research study

Evidence from rodent studies indicates that the beta-cell-derived neurohormone amylin exerts multiple effects on eating behavior, including reductions in meal size, intake of highly palatable foods, and stress-induced sucrose consumption. To assess the effect of amylin agonism on human eating behavior we conducted a randomized, blinded, placebo-controlled, multicenter study investigating the effects of the amylin analog pramlintide on body weight, 24-h caloric intake, portion sizes, "fast food" intake, and perceived control of eating in 88 obese subjects. After a 2-day placebo lead-in, subjects self-administered pramlintide (180 microg) or placebo by subcutaneous injection 15 min before meals for 6 wk without concomitant lifestyle modifications. Compared with placebo, pramlintide treatment elicited significant mean reductions from baseline in body weight on day 44 (-2.1 +/- 0.3 vs. +0.1 +/- 0.4%, P < 0.001), 24-h caloric intake (-990 +/- 94 vs. -243 +/- 126 kcal on day 3, P < 0.0001; -680 +/- 86 vs. -191 +/- 161 kcal on day 43, P < 0.01), portion sizes, and caloric intake at a "fast food challenge" (-385 +/- 61 vs. -109 +/- 88 kcal on day 44, P < 0.05). Pramlintide treatment also improved perceived control of eating, as demonstrated by a 45% placebo-corrected reduction in binge eating scores (P < 0.01). The results of this translational research study confirm in humans various preclinical effects of amylin agonism, demonstrating that pramlintide-mediated weight loss in obese subjects is accompanied by sustained reductions in 24-h food intake, portion sizes, fast food intake, and binge eating tendencies.     

Nutritional management of hypertension: past, present, and future

A succinct overview of the nutritional management of hypertension, past, present, and future is presented. Prior to 1945, the low sodium diet and the rice-fruit diet were shown to be effective in reducing the blood pressure to normal levels in 35-40% of hypertensive patients. Between 1945 and the present, many studies were made on the effects of alcohol, water hardness, obesity, moderate restriction of sodium with increased potassium intake, increased dietary calcium, low animal and high unsaturated fat intake, and increased amounts of fiber in the diet. Criticisms are made of the very small magnitude, even if statistically significant, of blood pressure decreases and the too-short control periods in many instances, and also concerning the assumption of use of 24-h urinary sodium as an accurate index of the sodium intake, and of urinary creatinine as a physiological reference standard against the excretion of sodium. The author mentions, for possible future research, long-term studies of the effects of diets moderately restricted in sodium and high in potassium, of reducing weight and increasing physical activity in obese hypertensives, and of low animal and high polyunsaturated fat diets in patients with mild essential hypertension.     

Serum and urinary markers of skeletal muscle tissue damage after weight lifting exercise

The purpose of this study was to determine whether high intensity weight lifting exercise produces elevations of urinary 3-methylhistidine (3-MH), serum creatine kinase activity (CK), and serum myoglobin concentration (MY), and whether trained weight lifters differed in such responses when compared to a group of untrained subjects. Ten experienced male weight lifters (EWL) and seven untrained male subjects (IWL) performed three sets of six weight lifting exercises at 70%-80% of 1 RM. All subjects consumed a meat-free diet. The 3-MH:creatinine (3-MH:CR) values decreased 24 h and 48 h following exercise (P less than 0.05). The 12-h and 24-h postexercise CK response and the 12-h postexercise MY response increased for both EWL and IWL (P less than 0.05). However, EWL had a lower 24-h postexercise CK response and lower 12-h and 24-h postexercise MY responses compared to IWL (P less than 0.05). Within 48 h following weight lifting exercise, skeletal muscle protein degradation (as assessed by 3-MH:CR values) decreased regardless of prior training experience whereas skeletal muscle tissue damage (as assessed by CK and MY responses) increased. However, prior weight lifting training appeared to diminish the extent of muscle tissue damage.