One-year dietary toxicity study with methidathion in beagle dogs.

The purpose of this study was to determine the chronic toxicity of methidathion, an organophosphate insecticide, in dogs. Groups of beagle dogs, four/sex/dose, were fed methidathion at constant dietary concentrations of 0, 0.5, 2, 4, 40, or 140 ppm for 1 year. The equivalent daily dosages were approximately 0, 0.02, 0.07, 0.15, 1.4, and 4.7 mg/kg. There were no deaths or adverse clinical signs associated with the treatment. Weekly body weights and weight gains were not affected. Mean daily food consumption was reduced in male dogs given the 140-ppm diet. Major treatment-related effects were cholestasis, chronic inflammation in the liver, and cholinesterase (ChE) inhibition. The liver effects were indicated by gross and microscopic pathologic findings as well as moderate increases in serum bile acids and enzyme activities (alanine aminotransferase, aspartate aminotransferase, sorbitol dehydrogenase, and alkaline phosphatase) in all dogs receiving greater than or equal to 40 ppm. RBC ChE was inhibited in males at greater than or equal to 40 ppm and in females and 140 ppm. Brain ChE was inhibited in both sexes at 140 ppm; the magnitude of inhibition relative to control was slightly greater with the cerebellar fraction than with the cerebral fraction. Serum ChE was not affected at any dose level. In conclusion, liver was the target organ in beagle dogs given greater than or equal to 40 ppm (equivalent to 1.4 mg/kg/day) methidathion in diet for 1 year. The no-observable-effect level was 4 ppm (0.15 mg/kg/day) for both liver cholestasis and ChE inhibition.

Diet, hormonal, and metabolic factors affecting bone mineral density in adolescent amenorrheic and eumenorrheic female runners.

Seven adolescent female runners with secondary amenorrhea and six adolescent eumenorrheic female runners received dietary supplements of 1200 mg calcium carbonate and 400 IU vitamin D/d for 12 months. Bone mineral density (BMD) of the axial skeleton was measured by dual photon densitometry at the beginning and end of the 12 month period. Plasma estradiol and ionized calcium concentration were also determined. Bone mineral density decreased in two of the amenorrheic subjects, with the lowest estradiol values concurrent with the severest training regimen and highest calcium intake. There was a significant decrease in plasma estradiol concentration in the amenorrheic runners (p less than 0.05). Plasma ionized calcium and estradiol explained 99% of the variation in BMD (r2 = 0.999). A significant inverse relationship between plasma estradiol and miles run/week was observed (r2 = -0.748). Adolescent female runners who train extensively and have low plasma estradiol levels may be adversely affecting BMD despite supplemental calcium and vitamin D intake.

Menstrual function and eating behavior in female recreational weight lifters and competitive body builders.

A group of 103 female weight lifters (WL) and 92 control (C) women answered a survey concerning eating behavior and attitudes (including the Eating Disorder Inventory) and menstrual function. The incidence of menstrual dysfunction, defined as oligomenorrhea plus amenorrhea, was significantly higher for the WL (30%) than for the C (13%) not on contraceptive pills. Only 2% of the women had amenorrhea. The incidence of dysfunction was highest for the subset of 12 WL who had competed in at least one body building competition (COMP); 86% of the COMP not on birth control pills had menstrual dysfunction (P less than 0.05). More WL than C reported missing at least one menstrual period during the last year (P = 0.06). WL scored significantly higher than C on the Drive for Thinness subscale of the Eating Disorder Inventory (EDI). Fifteen percent of the WL and 9% of the C achieved the criteria on this subscale for being weight preoccupied (P greater than 0.05). Significantly more WL than C responded that they were terrified of becoming fat (WL 56%, C 38%), were obsessed with food (WL 47%, C 30%), used laxatives for weight control (WL 14%, C 1%), and claimed that they had been anorexic in the past (WL 17%, C 5%). Examination of the answers of COMP revealed several items that were significantly different from the remainder of the WL. For example, 42% used to be anorexic, 67% were terrified of becoming fat, and 50% experienced uncontrollable urges to eat.(ABSTRACT TRUNCATED AT 250 WORDS)

An experimental evaluation of a prototype public access nutrition information system for supermarkets.

Located the Nutrition for a Lifetime System (NLS-1), a prototype interactive information system, in a large supermarket to help users decrease high-fat food purchases and increase high-fiber food purchases. Study participants were randomly assigned to control (n = 23; used the NLS-1 to enter food purchases only) or experimental (n = 26; viewed videodisc instructional programs, received prompts, made commitments, received feedback from the NLS-1) conditions. According to data entered in the NLS-1 and actual food shopping receipts, experimental participants significantly reduced higher fat purchases. Increases in higher fiber purchases favored the experimental group but were not significant.

Altering shoppers' supermarket purchases to fit nutritional guidelines: an interactive information system.

This study reports the results of one effort to help supermarket shoppers alter food purchases to make purchases (and meals) that are lower in fat and higher in fiber. A prototype interactive information system using instructional video programs, feedback on purchases with specific goals for change, weekly programs, and the ability to track user interactions and intended purchases was evaluated. The major dependent measure was users' actual food purchases as derived from participants' highly detailed supermarket receipts. After a 5- to 7-week baseline phase, participants were randomly assigned to an experimental or control condition for the 7- to 8-week intervention phase. A follow-up phase began 5 to 8 weeks after participants completed the intervention and discontinued use of the system. The results indicated that experimental participants, when compared to control participants, decreased high fat purchases and increased high fiber purchases during intervention, with evidence for some maintenance of effect in follow-up. Plans for increasing the use and impact of the system are discussed.

Aerobic exercise and resistance weight-training during weight reduction. Implications for obese persons and athletes.

Weight reduction is a goal common to obese persons and some athletic groups. An optimal weight loss programme for both populations should selectively deplete body fat while maintaining lean tissue. Another concern, particularly for athletes but also for obese persons participating in an exercise programme, is maintenance of physical performance. Treatments relying only on energy restriction commonly cause substantial loss of lean tissue, but the addition of aerobic exercise has frequently been shown to reduce this loss. Although less commonly used, resistance exercise appears to prevent loss of or even increase muscle mass during energy restriction. This type of exercise is less likely than aerobic exercise to acutely increase energy and lipid utilisation but may increase lean tissue, metabolic rate and thus indirectly aid weight reduction. Impairment of aerobic capacity, aerobic endurance, and muscle dysfunction has been demonstrated during energy restriction in athletes and obese persons. Incorporation of exercise into the weight loss programme may alleviate some of these negative consequences on performance. The addition of aerobic exercise of adequate intensity and duration has been shown to improve aerobic performance, even during severe energy restriction in obese individuals. Although resistance exercise will not cause an improvement of aerobic performance, increase in muscle size and strength have been noted concurrent with substantial weight loss. In summary, the value of aerobic exercise during weight loss is clear but the place of resistance exercise is intriguing but unresolved. To make development of ideal treatments for weight loss even more complex, the quantity of protein and carbohydrate in the energy-restricted diets may interact with the exercise prescription to determine the influence of the programme on body composition and physical performance in athletes and obese individuals.

Macronutrient content of a hypoenergy diet affects nitrogen retention and muscle function in weight lifters.

Weight lifters (WL) attempt to achieve a low body fat while maintaining fat free mass (FFM) and muscle function. Body composition and isometric muscular endurance were tested in 19 experienced male WL at the end of a weight maintenance and exercise routine standardization week. The subjects were assigned to either a control (C), moderate-protein (0.8 g.kg-1.d-1), high-carbohydrate hypoenergy diet (MP/HC), or high-protein (1.6 g.kg-1.d-1), moderate-carbohydrate hypoenergy diet (HP/MC). Both hypoenergy diets provided 75.3 kJ (18 kcal).kg-1.d-1. Apparent nitrogen balance (NBAL) was assessed using nitrogen in the diet, urine, and sweat. Body fat and FFM loss via hydrostatic weighing were not different between the hypoenergy groups. However, lean body mass (LBM) change as assessed by NBAL showed that the MP/HC group had an average negative NBAL of -3.19 g.d-1 while the HP/MC group had a positive NBAL of 4.13 g.d-1. Macronutrient mix did not affect biceps endurance, but quadriceps endurance declined for the HP/MC group during the experimental week. In conclusion, a hypoenergy diet providing twice the RDA for protein was more effective in retaining body protein in WL than a diet with higher carbohydrate but the RDA for protein. However, the lower carbohydrate of this diet contributed to reduced muscular endurance in these athletes.

Nutrition knowledge and concerns of health and physical education teachers.

The results indicated that most (80%) of the teachers were fairly knowledgeable about the nutrition needs of athletes. However, while many teachers agreed that carbohydrates and fats were the main sources of muscular energy, 35% indicated that protein was the primary source of energy for muscular activity. Also, 12% agreed that the consumption of salt tablets during athletic events prevents muscle cramps. The results suggest nutrition education for HPE teachers is needed. Information provided to HPE teachers should address their three main nutrition concerns, which are a balanced diet for athletes, weight control, and fluid replacement.

Glucocorticoid effects on contact hypersensitivity and on the cutaneous response to ultraviolet light in the mouse.

A single exposure to 254 nm ultraviolet irradiation (UV) can systemically suppress experimental sensitization to the simple allergen 2,4-dinitro, 1-chlorobenzene (DNCB) in the mouse. We show here that topical application at the site of irradiation of the 21-oic acid methyl ester derivative of the synthetic glucocorticoid triamcinolone acetonide (TAme) prevents UV suppression of sensitization. That is, mice painted with TAme at the site of UV exposure developed normal contact hypersensitivity (CH); mice exposed to UV only, like mice treated with the parent compound triamcinolone acetonide (TA), failed to be sensitized by DNCB applied to a distal site. TAme is inactivated rapidly by plasma esterases, so its effect is thought to be confined to the skin. Apparently, TAme blocked the cutaneous signal(s) for systemic suppression of CH. Histologically, irradiated skin exhibited mild inflammation and hyperproliferation, but these effects were greatly exaggerated and prolonged in the UV + TAme-treated skin, independent of sensitization at the distal site. The infiltrate consisted mostly of neutrophils and lacked the round cells characteristic of cell-mediated immunity. Apparently, normal immune suppression by UV prevented this vigorous reaction to irradiated skin. Applied together with DNCB. TAme blocked sensitization. It also prevented response to challenge by DNCB in previously sensitized animals. However, unlike the parent compound triamcinolone acetonide (TA), Budesonide or Beclomethasone diproprionate, each of which can penetrate the epidermis in active form, TAme had no effect on sensitization when applied at a distal site. Likewise, TAme did not affect plasma B (17-desoxycortisol) levels, whereas the other three compounds reduced plasma B tenfold, as expected of compounds causing adrenal-pituitary suppression. The results as a whole show that glucocorticoids can specifically inhibit cutaneous steps in induction of cell-mediated immunity or its suppression, and can, at the site of challenge, prevent its expression in CH.

Exercise capacity and nitrogen loss during a high or low carbohydrate diet.

Twelve obese women completed a maximal and an endurance exercise test (70% peak VO2) during a weight maintenance week. For the next 4 wk, the women consumed either a high (71%) carbohydrate (HC) or a low (33%) carbohydrate (LC), isonitrogenous very-low-calorie diet (VLCD) of 2,219 kJ (530 kcal).d-1. A supervised exercise session at 60% peak VO2 took place 3 times.wk-1 for 30 to 45 min. Peak VO2 and exercise endurance tests were repeated during the fourth week of the VLCD. One week of a 4,186 kJ (1000 kcal) diet followed the VLCD. The average weekly weight loss was 1.7 +/- 0.1 kg for the HC group and 2.0 +/- 0.2 kg for the LC group. Urinary nitrogen loss was greater for the LC group early in the VLCD but not different than HC over the entire experimental period. Serum cholesterol and high-density lipoprotein-cholesterol decreased in both groups but the ratio of these lipids improved over the treatment. Serum beta-hydroxybutyrate and uric acid increased significantly more for the LC than the HC group. Although absolute peak VO2 decreased, VO2 relative to body weight was maintained. Time to exhaustion improved by 36% for both groups in the endurance exercise tests. The endurance exercise R ratio was significantly more depressed by the LC than the HC treatment. In summary, both supervised treatments were effective in causing substantial weight reduction and improved blood lipid profiles in healthy young women but caused a net loss of body protein. Neither treatment compromised ability to participate in a thrice weekly exercise program. Although peak aerobic capacity did not increase, aerobic endurance at a fixed sub-maximal exercise load was improved.

The effect of varying carbohydrate content of a very-low-caloric diet on resting metabolic rate and thyroid hormones.

Twelve obese women were studied to determine the effects of the combination of an aerobic exercise program with either a high carbohydrate (HC) very-low-caloric diet (VLCD) or a low carbohydrate (LC) VLCD diet on resting metabolic rate (RMR), serum thyroxine (T4), 3,5,3'-triiodothyronine (T3), and 3,5,3'-triiodothyronine (rT3). The response of these parameters was also examined when subjects switched from the VLCD to a mixed hypocaloric diet. Following a maintenance period, subjects consumed one of the two VLCDs for 28 days. In addition, all subjects participated in thrice weekly submaximal exercise sessions at 60% of maximal aerobic capacity. Following VLCD treatments, participants consumed a 1,000 kcal mixed diet while continuing the exercise program for one week. Measurements of RMR, T4, T3, and rT3 were made weekly. Weight decreased significantly more for LC than HC. Serum T4 was not significantly affected during the VLCD. Although serum T3 decreased during the VLCD for both groups, the decrease occurred faster and to a greater magnitude in LC (34.6% mean decrease) than HC (17.9% mean decrease). Serum rT3 increased similarly for each treatment by the first week of the VLCD. Serum T3 and rT3 of both groups returned to baseline concentrations following one week of the 1,000 kcal diet. Both groups exhibited similar progressive decreases in RMR during treatment (12.4% for LC and 20.8% for HC), but values were not significantly lower than baseline until week 3 of the VLCD. Thus, although dietary carbohydrate content had an influence on the magnitude of fall in serum T3, RMR declined similarly for both dietary treatments.

A battery of potential alternatives to the Draize test: uridine uptake inhibition, morphological cytotoxicity, macrophage chemotaxis and exfoliative cytology.

Four assays that may serve as components of a battery of alternatives to the conventional Draize test were described. The exfoliative cytology assay is a refinement of the Draize test that may provide a more sensitive and more objective end-point. The macrophage migration assay addresses the inflammatory aspects of the physiological response to irritation. The uridine uptake inhibition assay uses a quantitative, reversible end-point to detect the short-term action of agents on cell membranes and cell phosphorylative potential. Finally, the cytological assay serves as a rapid, easily performed general indicator of cytotoxic action. The two latter assays have been demonstrated to correlate very well with Draize test results and with each other for a wide range of test agents.

Exercise training improves insulin sensitivity in the obese Zucker rat.

The effect of exercise on in vivo insulin sensitivity was examined in lean and obese Zucker rats. Rats (6 to 7 weeks of age) were swum two hours per day or kept sedentary for 8 weeks. Exercise decreased body weight gain as well as percent of fat in both genotypes. Sedentary obese rats had 62% higher gastrocnemius citrate synthase activity per gram of muscle than did lean rats. Exercise increased activity of this oxidative enzyme similarly in both genotypes. Compared to lean rats, obese rats had higher plasma-insulin levels and were less sensitive to insulin during an insulin tolerance test. Although training had no effect on plasma-insulin levels, exercise trained obese rats showed a greater drop in plasma glucose relative to sedentary controls following intravenous injection of three concentrations of insulin. It was concluded that moderate exercise training improved the insulin sensitivity of the obese Zucker rat.

Lipoprotein lipase activity and lipolysis after swim training in obese Zucker rats.

Obese and lean Zucker rats, 7 wk old, were swim trained or kept sedentary. Another group of obese rats was food restricted and exercised. Half the rats were killed after training for 8 wk, the remainder were retired and killed after an additional 8 wk. Neither treatment decreased adipocyte size in obese rats. Although basal lipolysis per cell was elevated in obese rats, their adipocytes were insensitive to epinephrine at 15 and 23 wk of age. Exercise training did not affect lipolysis. At all ages, adipose lipoprotein lipase (LPL) capacity was higher in obese relative to lean rats. In obese rats, swim training and exercise plus food restriction increased adipose and gastrocnemius LPL activity and depressed plasma insulin and triglyceride levels. All effects of exercise were transient. Thus, exercise training improved some of the metabolic disturbances in the Zucker obese rat but did not normalize adipocyte size, LPL activity, or lipolysis.

Exfoliative cytology as a refinement of the Draize eye irritancy test.

Collection of exfoliated cells from the eyes of albino rabbits was performed in conjunction with the Draize ocular irritancy test. At standard intervals after exposure to alcohols of known irritancy, exfoliated cells were retrieved from the conjunctival sac with a distilled water corneal rinse. These cells were fixed and then counted, centrifuged and stained by the method of Papanicolaou. The number of cells which were retrieved, correlated well with Draize test scores. This non-invasive modification of the Draize test was well tolerated by rabbits and provides an objective assessment of ocular irritancy. It is hoped that this refinement of the Draize test will reduce the numbers of animals used and provide more objective data upon which validation procedures for alternative methods can be based.

Role of physical activity in the etiology and treatment of childhood obesity.

Children in the United States are getting fatter and less active. Some childhood obesity undoubtedly develops from overeating but underactivity contributes to this condition. Various studies document less movement and lower intensity of activity in obese youth. An increase in physical activity is desirable since the health-related fitness components of flexibility, muscular and cardiovascular endurance can be improved in addition to the primary goal of body fat reduction. Evidence from animal studies suggests that exercise may alter adipose cell proliferation as well as total fat mass if initiated during growth. Regaining the natural inclination of children to be physically active may require efforts by physicians, parents, schools and special clinics. An increase in physical activity during childhood may help prevent chronic adult diseases related to inactivity and obesity.

Effect of swim training on development of obesity in the genetically obese rat.

Seven-week-old female lean and obese Zucker rats were swim trained or kept sedentary for 8 wk. Another group of obese rats was exercised plus food restricted. During exercise training, obese and lean rats ate more but gained less body weight than sedentary controls. Exercise favorably altered body composition, adipose cellularity, and plasma insulin of the obese rat. Exercise plus food restriction more dramatically affected body composition and adipose cellularity but was no more effective in depressing hyperinsulinemia than exercise alone. Following 8 wk of retirement, dorsal fat cell number remained depressed to formerly exercised obese rats whereas adipose cellularity in other depots, body composition, and plasma insulin were similar to control levels. Thus, exercise delayed but did not prevent the full development of obesity in the Zucker rat. Food restriction along with exercise resulted in more permanent effects on adipose cellularity than exercise alone but stunted muscle and skeletal growth.