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1.
Timing of food intake during simulated night shift impacts glucose metabolism: A controlled study.
Grant, CL, Coates, AM, Dorrian, J, Kennaway, DJ, Wittert, GA, Heilbronn, LK, Pajcin, M, Della Vedova, C, Gupta, CC, Banks, S
Chronobiology international. 2017;(8):1003-1013
Abstract
Eating during the night may increase the risk for obesity and type 2 diabetes in shift workers. This study examined the impact of either eating or not eating a meal at night on glucose metabolism. Participants underwent four nights of simulated night work (SW1-4, 16:00-10:00 h, <50 lux) with a daytime sleep opportunity each day (10:00-16:00 h, <3 lux). Healthy males were assigned to an eating at night (NE; n = 4, meals; 07:00, 19:00 and 01:30 h) or not eating at night (NEN; n = 7, meals; 07:00 h, 09:30, 16:10 and 19:00 h) condition. Meal tolerance tests were conducted post breakfast on pre-night shift (PRE), SW4 and following return to day shift (RTDS), and glucose and insulin area under the curve (AUC) were calculated. Mixed-effects ANOVAs were used with fixed effects of condition and day, and their interactions, and a random effect of subject identifier on the intercept. Fasting glucose and insulin were not altered by day or condition. There were significant effects of day and condition × day (both p < 0.001) for glucose AUC, with increased glucose AUC observed solely in the NE condition from PRE to SW4 (p = 0.05) and PRE to RTDS (p < 0.001). There was also a significant effect of day (p = 0.007) but not condition × day (p = 0.825) for insulin AUC, with increased insulin from PRE to RTDS in both eating at night (p = 0.040) and not eating at night (p = 0.006) conditions. Results in this small, healthy sample suggest that not eating at night may limit the metabolic consequences of simulated night work. Further study is needed to explore whether matching food intake to the biological clock could reduce the burden of type 2 diabetes in shift workers.
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2.
Normalizing effect of bright light therapy on temperature circadian rhythm in patients with eating disorders.
Yamamotová, A, Papezová, H, Vevera, J
Neuro endocrinology letters. 2008;(1):168-72
Abstract
OBJECTIVES Light and food are important synchronizers of circadian rhythmicity. In eating disorders, the circadian rhythms of food intake and temperature are abnormal. METHODS We analyzed the effect of the morning light application on the circadian rhythm of tympanic temperature and its association with hunger and mood changes in the sample of 25 female patients hospitalized with DSM-IV diagnosis of eating disorders (14 bulimia nervosa and 11 anorexia nervosa) and in 6 healthy women. RESULTS Light therapy reduced interindividual variability of the temperature acrophase, synchronized the temperature and hunger rhythms and showed an antidepressant effect on patients with eating disorders. Bright light therapy normalized the circadian rhythm of body temperature in both anorexic and bulimic patients: phase advanced rhythm was delayed and phase delayed rhythm was advanced. In contrast with anorexic patients, the majority of bulimic patients had normal temperature rhythm before the therapy and this rhythm was not changed by the therapy. CONCLUSION The light therapy normalized temperature circadian rhythm in patient with eating disorders. We hypothesize that the light therapy can also contribute to improvement of pathological eating pattern because of the functional connections between light and food entrained oscillators. The light may help to restore the irregular circadian rhythmicity induced by chaotic food intake.
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3.
Low-dose repeated caffeine administration for circadian-phase-dependent performance degradation during extended wakefulness.
Wyatt, JK, Cajochen, C, Ritz-De Cecco, A, Czeisler, CA, Dijk, DJ
Sleep. 2004;(3):374-81
Abstract
OBJECTIVE To investigate whether the effectiveness of a novel high-frequency low-dose caffeine regimen in counteracting the deterioration of performance during extended wakefulness is related to its interaction with homeostatic or circadian signals modulating performance and sleep propensity. DESIGN Double-blind, placebo-controlled, parallel-group design in a 29-day forced desynchrony paradigm in which the period of the sleep-wake cycle was scheduled to be 42.85 hours, i.e., far removed from the circadian range. This design allowed for separate estimation of the sleep homeostatic, circadian, and caffeine contributions to performance deficits or improvements. SETTING Private suite of a general clinical research center, in the absence of time of day information. PARTICIPANTS Sixteen healthy normal-sleeping men (aged 18-30 years) INTERVENTIONS Caffeine (0.3 mg per kg per hour) or placebo was administered hourly during the 28.57-hour wake episodes. RESULTS Plasma caffeine concentrations rose in an exponential saturating manner during wakefulness. Rising caffeine levels markedly attenuated wake-dependent deterioration of a number of measures of cognitive performance, particularly at the circadian performance nadir. Moreover, caffeine enhanced the ability of subjects to remain consistently awake for extended periods, holding subjects back from completing the full transition to sleep, but at the expense of increasing subjective sleepiness. CONCLUSIONS High-frequency low-dose caffeine administration is effective in countering the detrimental performance effects of extended wakefulness. These data are in accordance with the hypothesis that adenosine is a mediator of performance decrements associated with extended wakefulness and may lead to new strategies to use caffeine in situations in which neurobehavioral functioning is affected by sleep loss.
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4.
Normalization of daytime triglyceridemia by simvastatin in fasting normotriglyceridemic patients with premature coronary sclerosis.
van Wijk, JP, Halkes, CJ, De Jaegere, PP, Plokker, HW, Erkelens, DW, Cabezas, MC
Atherosclerosis. 2003;(1):109-16
Abstract
Postprandial hyperlipidemia is associated with premature coronary sclerosis in fasting normolipidemic subjects. Self-determined daytime capillary triglyceride (cTG) profiles were compared between 26 fasting normotriglyceridemic patients with premature coronary artery disease (CAD) and 26 controls matched for gender, age and BMI. Daytime triglyceridemia was calculated as total area under the cTG-curve (cTG-AUC). Total and LDL cholesterol were not different between CAD patients (5.4+/-0.8 mmol/l and 3.6+/-0.7 mmol/l, respectively) and controls (5.0+/-0.9 mmol/l and 3.3+/-0.8 mmol/l, respectively). Patients with CAD were characterized by a 44% higher cTG-AUC than matched controls (P<0.01). Using logistic regression analysis, cTG-AUC was the strongest predictor of the presence of CAD (P<0.001). Adding apo AI to the model improved the predictive power from 71 to 77%. Sixteen patients were studied after increasing doses of simvastatin up to 80 mg/day. Although the target for LDL cholesterol was reached by simvastatin 20mg/day, significant effects on cTG-AUC were found only by higher doses of simvastatin. Simvastatin 40 mg/day decreased cTG-AUC by 28% (P<0.05 versus baseline), reaching comparable values as in controls, without further improvement with simvastatin 80 mg/day (26% reduction versus baseline; P<0.05). Daytime triglyceridemia is linked to premature coronary sclerosis in fasting normotriglyceridemic patients. A higher dose of simvastatin was needed to normalize daytime triglyceridemia than was required to "normalize" LDL cholesterol.
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5.
Circadian organization of serum electrolytes in physiological aging.
Trotti, R, Rondanelli, M, Cuzzoni, G, Magnani, B, Gabanti, E, Ferrari, E
Functional neurology. 2003;(2):77-81
Abstract
Age-related structural and neurochemical changes occurring in the central nervous system have been related to changes in some rhythmometric parameters. In spite of their clinical importance, only a few studies have investigated the modifications over time of serum electrolytes in senescence. The aim of our study was to evaluate the circadian pattern of serum potassium, chloride, sodium, calcium and phosphorus in 30 clinically healthy elderly subjects, with no cognitive impairment, and to compare the findings with those given by 24 healthy young controls. The subjects were synchronized as regards their daily activities, sleeping/waking habits, time/quality of meals and dietary electrolyte intake. After an overnight fast, samples were taken beginning at 08.00 and every 4 h thereafter until 20.00, and every 2 h from 20.00 to 04.00. Both the young and the elderly subjects exhibited statistically significant circadian rhythms for all serum electrolytes considered. Our findings suggest that circadian organization of serum electrolytes is maintained in physiological aging, even though it should be noted that sodium and phosphorus acrophases differed significantly in the two experimental groups.
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6.
Endocrine responses to nocturnal eating--possible implications for night work.
Holmbäck, U, Forslund, A, Lowden, A, Forslund, J, Akerstedt, T, Lennernäs, M, Hambraeus, L, Stridsberg, M
European journal of nutrition. 2003;(2):75-83
Abstract
BACKGROUND Night work is becoming more common and shift workers display several metabolic disturbances. Aim To study the endocrine responses in relation to time of day during a 24-h period and how dietary macronutrient composition affects these responses. DESIGN Seven males (26-43 y and 19.9-26.6 kg. m(-2)) were studied in a crossover design. Isocaloric diets described as high-carbohydrates (HC; 65 energy percent (E%) carbohydrates and 20E% fat) or high-fat (HF; 40E% carbohydrates and 45E% fat) were given. After a 6-day diet adjustment period, the subjects were kept awake for 24 h in a metabolic unit and were served an isocaloric meal (continuation of respective diet) every 4-h. Blood samples were taken throughout the 24-h period. RESULTS Insulin and leptin responses to meal intake differed with respect to time of day (p < 0.05). Time of day affected glucagon, thyroid stimulating hormone (TSH), free thyroxin (fT4), total triiodothyronine (tT3), cortisol, chromogranin A (CgA) and pancreatic polypeptide (PP) concentrations (p < 0.05). Meal intake decreased cortisol concentration after meals at 0800, 1200 and 0400 but not at 1600, 2000 and 0000 h. The PP's postprandial increase was greater during 0800-1600 h compared to 2000-0800 h. With the HC meals, lower glucagon and CgA concentrations (p < 0.05), and a tendency for lower tT3 concentrations (p = 0.053) were observed compared to the HF meals. CONCLUSION Insulin, PP, TSH, fT4, cortisol and leptin responses to meal intake differed with respect to time of day. The decreased evening/nocturnal responses of cortisol and PP to meal intake indicate that nocturnal eating and night work might have health implications.
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7.
Role of vasopressin in 24-hour blood pressure regulation in diabetic patients with autonomic neuropathy.
Monteagudo, PT, Gavras, H, Gavras, I, Kohlmann, O, Ribeiro, AB, Zanella, MT
American journal of hypertension. 2002;(1 Pt 1):42-7
Abstract
To evaluate the role of vasopressin (AVP) on blood pressure (BP) in diabetic patients with autonomic neuropathy (AN), 10 patients were studied on a fixed sodium and potassium diet. On days 4 and 7, a 24-h BP monitoring, as well as blood and urine samples for sodium, potassium, creatinine, and osmolality determinations were obtained for every 4-h period; either placebo or an AVP-V1-antagonist (d(CH2)5Tyr(me)AVP; 0.5 mg; AVPi) were given iv at 1 PM. On placebo, systolic BP (SBP) showed a progressive elevation during the day, declining after 12 PM (8 AM to 12 AM 122+/-9; 12 AM to 4 PM 125+/-11; 4 PM to 8 PM 134+/-14; 8 PM to 12 PM 136+/-14; 12 PM to 8 AM 131+/-17 mm Hg). On AVPi this rise in SBP was blunted: 8 AM to 12 AM 125+/-122; 12 AM to 4 PM 121+/-21; 4 PM to 8 PM 126+/-16; 8 PM to 12 PM 129+/-14; 12 PM to 8 AM 124+/-12 mm Hg. Creatinine clearance and diureses were greater during the night, both with placebo and AVPi. Plasma osmolality did not change on either day, although serum sodium decreased after AVPi, reaching the lowest values at 4 PM to 8 PM period (137+/-4.7 v 131+/-3.8 mEq/L; P < .05). With placebo, fractional excretion of sodium (FENa) increased from 0.43%+/-0.32% during 12 h of orthostasis to 0.92%+/-1.05% during 12 h of recumbency (P < .02). With AVPi, the FENa on orthostasis did not differ from that with placebo, although BP values were lower and did not increase with recumbency (0.58+/-0.57 v 0.73%+/-0.49%; NS). In conclusion, our results show that in diabetic patients with AN, vasopressin participates in BP control by stimulating vascular and renal V1 receptors, which results in vasoconstriction and sodium reabsorption.
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8.
The effect of extend bar containing uncooked cornstarch on night-time glycemic excursion in subjects with type 2 diabetes.
Dyer-Parziale, M
Diabetes research and clinical practice. 2001;(3):137-9
Abstract
The objective of this study was to determine the effects of ingesting a snack bar containing uncooked cornstarch (Extend Bar, Clinical Products, Limited, Key Biscayne, FL) on nocturnal glycemic excursion in 28 adults (ages 22-78 years) with type 2 diabetes mellitus (mean HbAlc 8.21+/-1.28%). Thirteen subjects were treated with oral agents, eight with a combination of insulin and oral agents, and seven with insulin alone. Subjects ingested the study bar (Extend Bar, containing 30 g of total carbohydrate, including 5 g of uncooked cornstarch, 3 g protein, and 3 g fat) for three evenings followed by a placebo bar for 3 evenings (30 g of total carbohydrate, 3 g protein, and 3 g fat), or vice versa. Pre-snack before bedtime, midnight and before breakfast finger stick blood glucose levels were compared to determine the incidence of hypoglycemia (<60 mg/dl), hyperglycemia (>250 mg/dl), and to calculate any differences in the group's mean blood glucose levels when ingesting the study versus the placebo bar. There were no episodes of hypoglycemia or hyperglycemia. The mean blood glucose levels pre-snack at bedtime were nearly identical (Extend Bar value 117.5+/-45.6 mg/dl; placebo bar value 117.3+/-40.0 mg/dl; P=0.977), and lower at midnight and before breakfast on the Extend Bar nights compared to the placebo bar nights (Extend Bar, midnight value 127.9+/-31.0 mg/dl; placebo bar midnight value 148.2+/-32.1 mg/dl; P=0.0001; Extend Bar breakfast value 114.2+/-15.8 mg/dl; placebo bar breakfast value 158.49+/-30.3 mg/dl; P<0.0001). These data suggest that ingesting Extend Bar containing uncooked cornstarch as the nighttime snack may be an effective strategy to lesson the frequency of nocturnal and morning hyperglycemia in subjects with type 2 diabetes.
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9.
Twenty-four hour, ambulatory blood pressure responses following acute exercise: impact of exercise intensity.
Quinn, TJ
Journal of human hypertension. 2000;(9):547-53
Abstract
OBJECTIVES Mild to moderate acute, endurance exercise has generally been shown to reduce blood pressure (BP) in hypertensive (HT) individuals. Whether a slightly more strenuous bout of exercise can elicit a greater and more prolonged BP reduction is unknown. Therefore, the purpose of this study was to examine the effects of two, 30-min exercise bouts, conducted at 50% and 75% of maximal oxygen uptake (VO2max), on the quantity and quality of BP reduction over a 24-h period. METHODS Sixteen, Stage 1 and 2 non-medicated, HT (8 men/8 women) subjects were matched with normotensive (NT) men and women (n = 16). All subjects were evaluated for VO2max with a symptom-limited treadmill test and then completed a 30-min exercise bout at 50% and 75% of VO2max as well as a control (no exercise) session in random fashion on separate days. Twenty-four hour ambulatory BPs were measured after both the exercise and control settings. Data was assessed at 1, 3, 6, 12, and 24 h post-exercise and control session. RESULTS A repeated-measures ANOVA showed non-significant differences between HT men and women and that both exercise intensities, relative to the control session, significantly (P<0.05) reduced systolic (S) and diastolic (D) BPs. NT subjects showed non-significant reductions following both intensities. The reductions in the HT men and women averaged 4 and 9 mm Hg (SBP)/5 and 7 mm Hg (DBP) for 50% and 75%, respectively. On average, the HT subjects (men and women combined) maintained significant SBP reductions for 13 h after the 75% bout compared to 4 h after the 50% intensity. Likewise, DBP was reduced for an average of 11 h following the 75% bout compared to 4 h after the 50% intensity. CONCLUSIONS These results suggest that an exercise bout conducted between 50-75% VO2max significantly decreases SBP and DBP in HT subjects and that a greater and longer-lasting absolute reduction is evident following a 75% of maximum bout of exercise.