Effects of hemodialysis on serum lipids and phospholipids of end-stage renal failure patients

There is a link between diabetes and oxidative stress. Hyperglycaemia leads to free radical generation and alterations of endogenous antioxidants. Our aim is to study the effect of orally administered L-tryptophan (TRP), the melatonin precursor, an endogenous antioxidant, on circulating levels of glycaemia, insulin and melatonin, and on the superoxide dismutase and catalase antioxidant systems in non-diabetic (ND) and type 2 diabetic (n5-STZ) male Wistar rats. At 19:30 every day for 15 days, TRP (125 mg/kg body weight) was administered orally. At 09:00 every two days the glycaemia was measured and every day the intake of food and water was recorded. At the beginning and end of treatment (at 09:00; 21:00; 02:00) plasma insulin and melatonin levels were measured, and (at 09:00) the enzymatic activities of catalase and superoxide dismutase (SOD) in erythrocytes were also measured. Glycaemia values were greater (p < 0.01) in n5-STZ rats than in ND rats, while insulin levels were lower (p < 0.05) at all times studied and these parameters were not altered by the TRP administration. Melatonin levels at 02:00 were lower in n5-STZ than in ND rats (p < 0.05). The TRP administration did not modify the circulating melatonin levels in ND rats, but raised (p < 0.01) the levels at 02:00 in the treated n5-STZ group. In ND rats after TRP administration there was a decline in catalase activity (p < 0.05), while in n5-STZ rats there was a rise (p < 0.01) at the end of treatment. However, there were no significant changes in SOD activity. There was increased food intake (g/day) in the treated n5-STZ group (p < 0.01). In conclusion, the oral administration of TRP did not modify glycaemia or insulinaemia levels, but raised melatonin levels in diabetic rats at 02:00, lowered catalase activity in ND rats but raised it in n5-STZ rats, and increased food intake in n5-STZ rats.     

Timing Light Treatment for Eastward and Westward Travel Preparation

Jet lag degrades performance and operational readiness of recently deployed military personnel and other travelers. The objective of the studies reported here was to determine, using a narrow bandwidth light tower (500 nm), the optimum timing of light treatment to hasten adaptive circadian phase advance and delay. Three counterbalanced treatment order, repeated measures studies were conducted to compare melatonin suppression and phase shift across multiple light treatment timings. In Experiment 1, 14 normal healthy volunteers (8 men/6 women) aged 34.9±8.2 yrs (mean±SD) underwent light treatment at the following times: A) 06:00 to 07:00 h, B) 05:30 to 07:30 h, and C) 09:00 to 10:00 h (active control). In Experiment 2, 13 normal healthy subjects (7 men/6 women) aged 35.6±6.9 yrs, underwent light treatment at each of the following times: A) 06:00 to 07:00 h, B) 07:00 to 08:00 h, C) 08:00 to 09:00 h, and a no-light control session (D) from 07:00 to 08:00 h. In Experiment 3, 10 normal healthy subjects (6 men/4 women) aged 37.0±7.7 yrs underwent light treatment at the following times: A) 02:00 to 03:00 h, B) 02:30 to 03:30 h, and C) 03:00 to 04:00 h, with a no-light control (D) from 02:30 to 03:30 h. Dim light melatonin onset (DLMO) was established by two methods: when salivary melatonin levels exceeded a 1.0 pg/ml threshold, and when salivary melatonin levels exceeded three times the 0.9 pg/ml sensitivity of the radioimmunoasssy. Using the 1.0 pg/ml DLMO, significant phase advances were found in Experiment 1 for conditions A (p?<?.028) and B (p?<?0.004). Experiment 2 showed significant phase advances in conditions A (p?<?0.018) and B (p?<?0.003) but not C (p?<?0.23), relative to condition D. In Experiment 3, only condition B (p?<?0.035) provided a significant phase delay relative to condition D. Similar but generally smaller phase shifts were found with the 2.7 pg/ml DLMO method. This threshold was used to analyze phase shifts against circadian time of the start of light treatment for all three experiments. The best fit curve applied to these data (R²?=?0.94) provided a partial phase-response curve with maximum advance at approximately 9–11 h and maximum delay at approximately 5–6 h following DLMO. These data suggest largest phase advances will result when light treatment is started between 06:00 and 08:00 h, and greatest phase delays will result from light treatment started between 02:00 to 03:00 h in entrained subjects with a regular sleep wake cycle (23:00 to 07:00 h).     

Experimental Type 2 Diabetes Induces Enzymatic Changes in Isolated Rat Enterocytes

Diabetes in humans and in experimental animals produces changes in the function and structure of the small intestine. The authors determined the activity of intestinal disaccharidases (maltase and sucrase) and of 6-phosphofructo-1-kinase (PFK-1) in enterocytes isolated from the small intestine of male Wistar rats (2.5 to 3 months old) with experimental nonobese type 2 diabetes, induced by streptozotocin (STZ) injection on the day of birth (n0-STZ) or on the 5th day of life (n5-STZ), with different degrees of hyperglycemia and insulinemia (n0-STZ and n5-STZ models). The glycemia (mmol/L) of the diabetic rats (n0-STZ: 8.77 ± 0.47; n5-STZ: 20.83 ± 0.63) was higher (P < .01) than that of the nondiabetic (ND) rats (5.99 ± 0.63); on the contrary, the insulinemia (ng/mL) was significantly lower in both n0-STZ (1.74 ± 0.53; P < .05) and n5-STZ (1.12 ± 0.44; P < .01) diabetic rats than in normal rats (3.77 ± 0.22). The sucrase and maltase activities (U/g protein) in diabetic rats (n0-STZ: 89 ± 9 and 266 ± 12; n5-STZ: 142 ± 23 and 451 ± 57) were significantly higher than those in the ND group (66 ± 5 and 228 ± 22). The PFK-1 activities (mU/mg protein) in the diabetic models (n0-STZ: 14.89 ± 1.51; n5-STZ: 13.35 ± 3.12) were significantly lower (P < .05) than in ND rats (20.54 ± 2.83). The data demonstrated enzymatic alterations in enterocytes isolated fromthe small intestine of n0-STZ rats that are greater (P < .05) than in the more hyperglycemic and hypoinsulinemic n5-STZ animals. The results also show that nonobese type 2–like diabetes in the rat produces modifications that favor an increase in glucose absorption rates.     

Neuroprotective effect of melatonin on radiation-induced oxidative stress and apoptosis in the brainstem of rats

This study aimed to determine the effects of melatonin on irradiation-induced apoptosis and oxidative stress in the brainstem region of Wistar rats. Therefore, the animals underwent whole-brain X-radiation with a single dose of 25 Gy in the presence or absence of melatonin pretreatment at a concentration of 100 mg/kg BW. The rats were allocated into four groups (10 rats in each group): namely, vehicle control (VC), 100 mg/kg of melatonin alone (MLT), irradiation-only (RAD), and irradiation plus 100 mg/kg of melatonin (RAM). An hour before irradiation, the animals received intraperitoneal (IP) melatonin and then were killed after 6 hr, followed by measurement of nitric oxide (NO), malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), and total antioxidant capacity (TAC) in the brainstem region. Furthermore, the western blot analysis technique was performed to assess the caspase-3 expression level. Results showed significantly higher MDA and NO levels in the brainstem tissues for the RAD group when compared with the VC group (p < .001). Moreover, the irradiated rats exhibited a significant decrease in the levels of CAT, SOD, GPx, and TAC (p < .01, p < .001, p < .001, and p < .001, respectively) in comparison to the VC group. The results of apoptosis assessment revealed that the expression level of caspase-3 significantly rose in the RAD group in comparison with the VC group (p < .001). Pretreatment with melatonin ameliorated the radiation-induced adverse effects by decreasing the MDA and NO levels (p < .001) and increasing the antioxidant enzyme activities (p < .001). Consequently, the caspase-3 protein expression level in the RAM group showed a significant reduction in comparison with the RAD group (p < .001). In conclusion, melatonin approximately showed a capacity for neuroprotective activity in managing irradiation-induced oxidative stress and apoptosis in the brainstem of rats; however, the use of melatonin as a neuroprotective agent in humans requires further study, particularly clinical trials.     

Light Exposure Among Adolescents With Delayed Sleep Phase Disorder: A Prospective Cohort Study

The objective of this study was to compare light exposure and sleep parameters between adolescents with delayed sleep phase disorder (DSPD; n?=?16, 15.3?±?1.8 yrs) and unaffected controls (n?=?22, 13.7?±?2.4 yrs) using a prospective cohort design. Participants wore wrist actigraphs with photosensors for 14 days. Mean hourly lux levels from 20:00 to 05:00?h and 05:00 to 14:00?h were examined, in addition to the 9-h intervals prior to sleep onset and after sleep offset. Sleep parameters were compared separately, and were also included as covariates within models that analyzed associations with specified light intervals. Additional covariates included group and school night status. Adolescent delayed sleep phase subjects received more evening (p?<?.02, 22:00–02:00?h) and less morning (p?<?.05, 08:00–09:00?h and 10:00–12:00?h) light than controls, but had less pre-sleep exposure with adjustments for the time of sleep onset (p?<?.03, 5–7?h prior to onset hour). No differences were identified with respect to the sleep offset interval. Increased total sleep time and later sleep offset times were associated with decreased evening (p?<?.001 and p?=?.02, respectively) and morning (p?=?.01 and p?<?.001, respectively) light exposure, and later sleep onset times were associated with increased evening exposure (p?<?.001). Increased total sleep time also correlated with increased exposure during the 9?h before sleep onset (p?=?.01), and a later sleep onset time corresponded with decreased light exposure during the same interval (p?<?.001). Outcomes persisted regardless of school night status. In conclusion, light exposure interpretation requires adjustments for sleep timing among adolescents with DSPD. Pre- and post-sleep light exposures do not appear to contribute directly to phase delays. Sensitivity to morning light may be reduced among adolescents with DSPD. (Author correspondence: auger.raymond1@mayo.edu)     

Circadian rhythm gene expression and daily melatonin levels vary in athletes and sedentary males

The circadian rhythm is a 24-h cycle in which cells control metabolic and physiological processes throughout the day. In this study, we compared the expression patterns of major circadian rhythm-related genes: from blood of Bmal1, Ror-α, Cry1, Per2, Per1, and Nr1d1. In addition, changes in patterns of melatonin levels were observed in 16 subjects, eight males rugby players and eight males who did not exercise regularly. Blood was collected at 6:00, 10:00, 18:00, and 22:00. Bmal1, Ror-α, Cry1, Per2 (p < 0.001), Per1 (p < 0.01), and Nr1d1 (p < 0.05) genes related to circadian rhythm was higher in rugby players than in sedentary males. However, melatonin levels were higher in sedentary males than in rugby players (p < 0.05). These results indicate that long-term exercise in athletes can increase the expression of genes related to circadian rhythm and these may have an effect on daily melatonin levels as well.     

AGING AND THE CIRCADIAN RHYTHM OF MELATONIN: A CROSS-SECTIONAL STUDY OF CHINESE SUBJECTS 30–110 YR OF AGE

Although previous reports indicate that nocturnal plasma melatonin secretion declines with age, some recent findings do not support this point. In the present cross-sectional study, we documented serum melatonin concentrations at two time points, 02:00 and 08:00h, in 144 persons aged 30–110 yr and found a significant age-related decline. It began around the age of 60 and reached a very significantly lower level in subjects in their 70s and over 80 yr of age (P<0.01, when compared with age <60 yr). Nocturnal melatonin levels were higher among (post-menopausal only) women than men overall (P<0.05). In the older age-groups, nocturnal melatonin levels did not differ between healthy controls and subjects with high blood pressure or ischemic heart disease. To further check these results, we also assessed the circadian pattern of serum melatonin in four subgroups of healthy men, aged 30–39, 40–49, 50–59, and 60–69 yr: blood samples were taken at 2h intervals from 08:00 to 22:00h and hourly from 22:00 to 08:00h. Our results showed generally similar circadian melatonin patterns that peaked at night with very low levels during the daytime. No significant difference was found among the three younger groups, but nocturnal melatonin levels were significantly lower in the men in their 60s.     

Hepatitis B virus replication causes oxidative stress in HepAD38 liver cells

The essential amino acid tryptophan is the precursor in the anabolic pathway of melatonin, a hormone with immunomodulatory properties. The present study shows the in vivo effect of tryptophan on the phagocytic function and oxidative metabolism of heterophils from Streptopelia roseogrisea of < 1 year of age, with a parallel evaluation of the plasma levels of melatonin. The L-tryptophan was administered orally (125 and 300 mg/kg b.w.) at 19:00, before the beginning of the period of darkness, for 7 days. At the end of the tryptophan treatment, determinations were made at 21:00 and 02:00 of the Phagocytosis Index, the Phagocytosis Percentage, the Phagocytic Efficiency and the superoxide anion levels in heterophils isolated from blood and of the plasma levels of melatonin. The results showed, for the determinations at 21:00 in the animals that had received 125 mg L-tryptophan/kg b.w., enhanced heterophil phagocytic function and raised levels of plasma melatonin, with no affect on the oxidative metabolism of the phagocytes. For the administration of the greater concentration of tryptophan (300 mg/kg b.w.), there were raised plasma melatonin levels together with increases in heterophil phagocytic capacity and phagocyte oxidative metabolism at 02:00. The results indicate that tryptophan administered orally at night to diurnal animals of less than 1 year in age affects the circulating levels of melatonin at the same time as inducing stimulation of the innate immune function.     

Effects of zinc deficiency and pinealectomy on cellular immunity in rats infected with Toxoplasma gondii

The effects of zinc and/or melatonin deficiencies on cellular immunity were investigated in rats infected with Toxoplasma gondii. A total of 50 adult male Sprague-Dawley rats were divided into 5 groups of 10 rats each. In group I, the rats were infected with T. gondii and fed a zinc-deficient diet; in group II, the rats were infected and their pineal gland was surgically removed. Group III included rats that were infected, pinealectomized, and fed a zinc-deficient diet. Group IV consisted of T. gondii-infested rats that received no treatment of any kind, and group V were normal controls. After 3 wk of treatment, all rats were sacrificed and the percentages of CD3, CD4, and CD8 lymphocytes, zinc, and melatonin levels in plasma and the percentage of lymphocyte in blood smears were analyzed. The CD3 ratios of groups I–III were significantly lower than those of groups IV and V (p<0.01). The CD4 lymphocytes were significantly higher in group IV than that in all other groups (p<0.05). In group IV, the CD8 lymphocytes were higher than in groups I–III (p<0.01) and those in group V were higher than for groups I and III (p<0.01). Lymphocyte incidence in group IV was higher than in the other four groups (p<0.01). The plasma zinc and plasma melatonin levels in groups I–III were significantly lower than those in the controls (p<0.01, both cases). These results suggest that zinc and/or melatonin deficiency have a negative influence on cellular immunity in rats with toxoplasmosis.     

Effects of zinc and melatonin deficiency on testicular tissue of rats

The present study was designed to investigate the effects of zinc and/or melatonin deficiency on rat testes. A total of 24 adult male Sprague-Dawley rats were used in this study. The rats were divided into four groups of six rats each, as follows: (I) controls, (II) zinc deficient, (III) pinealectomized, zinc normal, and (IV) pinealectomized, zinc deficient. The plasma zinc levels in the control group were higher than in all the other groups (p<0.01), and those of the zinc-deficient groups II and IV were significantly lower than for group III (p<0.01). The melatonin levels in the controls were also significantly higher than for all other groups (p<0.01) There was no significant difference in sperm production between the controls and the group of animals that had no epiphysis. A significant suppression was observed in the spermatogenetic activity of the zinc-deficient groups (p<0.01). The suppression was higher in group II than in group IV. These results indicate that testicular damage caused by zinc deficiency may be reduced by melatonin deficiency.     

24-Hour Pattern of Work-Related Injury Risk of French Firemen: Nocturnal Peak Time

The first aim of the study was to assess clock-time patterning of work-related injuries (WRIs) of firemen (FM) of Saône et Loire-71 (France) during the 4-yr span of 1 January 2004 to 31 December 2007. FM of this service are legally required to log every WRI and seek its evaluation by the medical service, whether the WRI was the result of worksite duties or exercise/sport activities at the station. WRI was defined specifically as a (nonexercise, nonsport, and nonemotional/stress) work-associated trauma, verified both by log book and medical records. For the corresponding years, the 24-h pattern of emergency calls (Calls) plus road traffic (Traffic) on the main roads of the service area was also assessed. Relative risk (R) of WRI was calculated as the quantity of WRIs/h divided by the quantity of Call responses/h?×?1000, which takes into account the number of at-risk FM/unit time, since each dispatched emergency vehicle is staffed with 4 FM. Comparably trained regular (RFM) and volunteer (VFM) FM experienced a total of 187 WRIs. The 24-h WRI curve patterns of RFM and VFM were correlated (r?=?0.4, p?<?.05), with no histogram difference (p?>?.05). Analysis of variance (ANOVA) validated comparable clock-time patterns in WRIs of RFM and VFM each year and each season (all p?<?.0001). Thus, time series of the RFM and VFM were pooled, revealing a statistical significant 24-h variation in WRIs (ANOVA, p?>?.0006; Cosinor analysis, p?<?.0001), with peak at 16:00?h and trough at 04:00?h. The 24-h pattern in Traffic, which mirrors that of human activity, with peak ～18:00?h and trough ～03:00?h, was also verified (ANOVA, p <?.0001; Cosinor, p?<?.0001). Calls (n?=?112,059) resulting in FM responses also exhibited statistically significant 24-h variation, with peak at ～20:00?h and trough at ～06:00?h. The 24-h pattern of R showed a nocturnal peak at 02:00?h (R?=?2.87?±?0.46; mean?±?SEM) and diurnal trough 14:00?h (R?=?1.30?±?0.05) (t test, p?<?.02); clock-time-related changes in R were further validated by ANOVA (p?=?.0001) and Cosinor (p?<?.0001), with acrophase (peak time, Ø) of 02:43?h?±?68?min (SD). The second aim of the study was to evaluate the relationship between the 24-h patterns of WRIs and lag-time (LT) response (used as a measure of work performance) of FM of the same service to urgent medical calls for out-of-hospital cardiac arrests. Highest R of WRI at 02:00?h corresponded closely to longest LT (raw data at ～02:00?h and Cosinor derived Ø of 02.54?h?±?71?min [SD]), thereby supporting the hypothesis of a common mechanism underlying the two 24-h profiles. A third aim was to determine the relevance of a new concept in work safety, “chronoprevention,” for future FM training programs. (Author correspondence: bergarein@yahoo.fr)     

Melatonin Treatment Effects on Adolescent Students' Sleep Timing and Sleepiness in a Placebo-Controlled Crossover Study

During the last few decades, the incidence of sleep-onset insomnia, due to delay of circadian phase, has increased substantially among adolescents all over the world. We wanted to investigate whether a small dose of melatonin given daily, administered in the afternoon, could advance the sleep timing in teenagers. Twenty-one students, aged 14–19 yrs, with sleep-onset difficulties during school weeks were recruited. The study was a randomized, double blind, placebo (PL)-controlled crossover trial, lasting 5 wks. During the first 6 d in wks 2 and 4, the students received either PL or melatonin (1 mg) capsules between 16:30 and 18:00 h. During the first 6 d of wk 5, all students received melatonin. Wks 1 and 3 were capsule-free. In the last evening of each week and the following morning, the students produced saliva samples at home for later melatonin analysis. The samples were produced the same time each week, as late as possible in the evening and as early as possible in the morning. Both the student and one parent received automatic mobile text messages 15 min before saliva sampling times and capsule intake at agreed times. Diaries with registration of presumed sleep, subjective sleepiness during the day (Karolinska Sleepiness Scale, KSS) and times for capsule intake and saliva samplings were completed each day. Primary analysis over 5 wks gave significant results for melatonin, sleep and KSS. Post hoc analysis showed that reported sleep-onset times were advanced after melatonin school weeks compared with PL school weeks (p < .005) and that sleep length was longer (p < .05). After the last melatonin school week, the students fell asleep 68 min earlier and slept 62 min longer each night compared with the baseline week. Morning melatonin values in saliva diminished compared with PL (p < .001) and evening values increased (p < .001), indicating a possible sleep phase advance. Compared with PL school weeks, the students reported less wake up (p < .05), less school daytime sleepiness (p < .05) and increased evening sleepiness (p < .005) during melatonin weeks. We conclude that a small dose of melatonin given daily, administered in the afternoon, could advance the sleep timing and make the students more alert during school days even if they continued their often irregular sleep habits during weekends. (Author correspondence: arne.lowden@stress.su.se)     

Melatonin supplementation can ameliorate the detrimental effects of heat stress on performance and carcass traits of Japanese quail

Melatonin, the major pineal hormone, modulates growth in poultry by influencing hormones involved in growth. We investigated the effects of dietary melatonin supplementation on performance, carcass characteristics, and excretion of nitrogen and some minerals in broiler Japanese quails (Coturnix coturnix japonica) exposed to high-ambient-temperature stress (34°C). One hundred twenty Japanese quails (10 d old) were randomly assigned to 4 treatment groups, 3 replicates of 10 birds each. The birds were kept in either an environment-controlled room at a constant 22°C or were kept at 22°C for 16 h/d and at 34°C for 8 h/d (9:00 am to 5:00 pm). At both temperatures birds were fed either a basal diet or the basal diet supplemented with 40 mg of melatonin per kilogram of diet. The experiment lasted for 32 d. Melatonin improved feed efficiency in both temperatures groups compared with their corresponding controls. Although feed intake was similar in all groups, the improvement in feed efficiency was more noticable in melatonin-fed quails kept at high temperature (p<0.01). Supplemental melatonin significantly increased live weight gain and carcass characteristics under stress conditions (p<0.01) but did not show the same effect at thermoneutral conditions (p>0.05). Heat exposure increased excretion of N, Ca, P, Zn, Fe, and Cr and decreased retention rates for them. Dietary melatonin supplementation returned these values to normal (p<0.01). No interactions between melatonin and temperature were found in the parameters measured. The results of the study show that melatonin supplementation attenuated the retardation in performance as well as the excretion of minerals caused by heat stress in broiler quails. Our data suggest that melatonin might offer protection against heat-stress-related depression in the performance of broiler quails.     

Acute and delayed responses of C-reactive protein,malondialdehyde and antioxidant markers after resistance training session in elite weightlifters: Effect of time of day

The aim of this study was to investigate the effect of an Olympic-Weightlifting-session followed by 48-h recovery period on the oxidative and antioxidant parameters’ diurnal variation. Nine weightlifters (21?±?0.5 years) performed, in randomized order, three Olympic-Weightlifting-sessions at 08?h:00, 14?h:00 and 18?h:00. Blood samples were collected: at rest and 3?min and 48?h after each session. C-reactive protein (CRP), rate of lipid peroxidation and antioxidant activities were assessed. At rest, analysis of variance showed a significant time of day (TOD) effect (p?<?0.05) for uric acid, catalase and glutathione peroxidase with higher values at 14?h:00 and 18?h:00 compared with 08?h:00. However, no significant TOD effect for malondialdehyde, total bilirubin and CRP was observed. Given the profound changes (p?<?0.001) in the post-training session values, these diurnal variations have been altered immediately and even 48?h after the training sessions. Despite the significant decreases in the post-training values after the 48-h recovery period (p?<?0.05), levels of lipid peroxidation and enzymatic defense remained elevated (p?<?0.05) 48?h after the morning training session. However, after the afternoon and evening sessions, the same period was sufficient to return values to the baseline levels. In conclusion, the morning session seems to generate the most important acute and delayed lipid peroxidation responses. Therefore, weightlifting coaches should avoid scheduling their training sessions in the morning-hours.     

Circadian rhythms of melatonin in haemolymph and optic lobes of Chinese mitten crab (Eriocheir sinensis) and Chinese grass shrimp (Palaemonetes sinensis)

This study is the first to examine the circadian rhythms of melatonin in Eriocheir sinensis and Palaemonetes sinensis, two economically important crustaceans. We collected haemolymph and optic lobes from both species every 4 h over a whole day cycle. Melatonin content was measured with high-performance liquid chromatography. E. sinensis haemolymph exhibited significant (p < 0.05) peaks in melatonin at 16:00 (0.180 ± 0.020 μg·mL^?1) and 24:00 (0.244 ± 0.055 μg·mL^?1), while eyestalks had significant peaks at 16:00 (72.377 ± 18.100 μg·eyestalk^?1) and 24:00 (98.756 ± 30.271 μg·eyestalk^?1). In P. sinensis, melatonin peaked significantly only at 16:00 in optic lobes (12.493 ± 1.475 μg·eyestalk^?1) (p < 0.05); no significant peaks were present in haemolymph. Thus, both E. sinensis and P. sinensis exhibit species-specific melatonin rhythms. Time of day should therefore be considered when examining the physiological status of both crustaceans, given the potential influence of fluctuating daily melatonin concentrations.     

INCREASED SENSITIVITY TO LIGHT-INDUCED MELATONIN SUPPRESSION IN PREMENSTRUAL DYSPHORIC DISORDER

Increased sensitivity to light-induced melatonin suppression characterizes some, but not all, patients with bipolar illness or seasonal affective disorder. The aim of this study was to test the hypothesis that patients with premenstrual dysphoric disorder (PMDD), categorized as a depressive disorder in Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), have altered sensitivity to 200 lux light during mid-follicular (MF) and late-luteal (LL) menstrual cycle phases compared with normal control (NC) women. As an extension of a pilot study in which the authors administered 500 lux to 8 PMDD and 5 NC subjects, in the present study the authors administered 200 lux to 10 PMDD and 13 NC subjects during MF and LL menstrual cycle phases. Subjects were admitted to the General Clinical Research Center (GCRC) in dim light (<50 lux) to dark (during sleep) conditions at 16:00?h where nurses inserted an intravenous catheter at 17:00?h and collected plasma samples for melatonin at 30-min intervals from 18:00 to 10:00?h, including between 00:00 and 01:00?h for baseline values, between 01:30 and 03:00?h during the 200 lux light exposure administered from 01:00 to 03:00?h, and at 03:30 and 04:00?h after the light exposure. Median % melatonin suppression was significantly greater in PMDD (30.8%) versus NC (?0.2%) women (p?=?.040), and was significantly greater in PMDD in the MF (30.8%) than in the LL (?0.15%) phase (p?=?.047). Additionally, in the LL (but not the MF) phase, % suppression after 200 lux light was significantly positively correlated with serum estradiol level (p ?=? .007) in PMDD patients, but not in NC subjects (p?>?.05). (Author correspondence: bparry@ucsd.edu)     

Older Poor-Sleeping Women Display a Smaller Evening Increase in Melatonin Secretion and Lower Values of Melatonin and Core Body Temperature Than Good Sleepers

Melatonin concentration and core body temperature (CBT) follow endogenous circadian biological rhythms. In the evening, melatonin level increases and CBT decreases. These changes are involved in the regulation of the sleep-wake cycle. Therefore, the authors hypothesized that age-related changes in these rhythms affect sleep quality in older people. In a cross-sectional study design, 11 older poor-sleeping women (aged 62–72 yrs) and 9 older good-sleeping women (60–82 yrs) were compared with 10 younger good-sleeping women (23–28 yrs). The older groups were matched by age and body mass index. Sleep quality was assessed by the Pittsburgh Sleep Quality Index questionnaire. As an indicator of CBT, oral temperature was measured at 1-h intervals from 17:00 to 24:00?h. At the same time points, saliva samples were collected for determining melatonin levels by enzyme-linked immunosorbent assay (ELISA). The dim light melatonin onset (DLMO), characterizing the onset of melatonin production, was calculated. Evening changes in melatonin and CBT levels were tested by the Friedman test. Group comparisons were performed with independent samples tests. Predictors of sleep-onset latency (SOL) were assessed by regression analysis. Results show that the mean CBT decreased in the evening from 17:00 to 24:00?h in both young women (from 36.57°C to 36.25°C, p < .001) and older women (from 36.58°C to 35.88°C, p < .001), being lowest in the older poor sleepers (p < .05). During the same time period, mean melatonin levels increased in young women (from 16.2 to 54.1 pg/mL, p < .001) and older women (from 10.0 to 23.5 pg/mL, p < .001), being lowest among the older poor sleepers (from 20:00 to 24:00?h, p < .05 vs. young women). Older poor sleepers also showed a smaller increase in melatonin level from 17:00 to 24:00?h than older good sleepers (mean?±?SD: 7.0?±?9.63 pg/mL vs. 15.6?±?24.1 pg/mL, p = .013). Accordingly, the DLMO occurred at similar times in young (20:10?h) and older (19:57?h) good-sleeping women, but was delayed ～50?min in older poor-sleeping women (20:47?h). Older poor sleepers showed a shorter phase angle between DLMO and sleep onset, but a longer phase angle between CBT peak and sleep onset than young good sleepers, whereas older good sleepers had intermediate phase angles (insignificant). Regression analysis showed that the DLMO was a significant predictor of SOL in the older women (R²?=?0.64, p < .001), but not in the younger women. This indicates that melatonin production started later in those older women who needed more time to fall asleep. In conclusion, changes in melatonin level and CBT were intact in older poor sleepers in that evening melatonin increased and CBT decreased. However, poor sleepers showed a weaker evening increase in melatonin level, and their DLMO was delayed compared with good sleepers, suggesting that it is not primarily the absolute level of endogenous melatonin, but rather the timing of the circadian rhythm in evening melatonin secretion that might be related to disturbances in the sleep-wake cycle in older people. (Author correspondence: mdittmar@zoologie.uni-kiel.de)     

Influence of feeding a fish oil-containing diet to young,lean, adult dogs: effects on lipid metabolites,postprandial glycaemia and body weight

The aim of this study was to determine the effect of feeding a fish oil (FO)-containing diet on lipid and protein metabolism, postprandial glycaemia and body weight in young, lean, adult dogs. Eight female Beagles were randomly assigned to one of two isonitrogenous and isoenergetic diets, Control or FO, in a crossover design. At the beginning of the experiment and at 30 and 60 d, a baseline blood sample was collected and the dogs then were fed their daily ration. Nitrogen balance began at 07:00 h on day 63 of each experimental period and ended at 07:00 h on day 69. On day 66 of each period, a single dose (7.5 mg/kg) of ¹⁵N-glycine was administered orally to each dog via gelatin capsule. Postprandial glycaemia did not differ between treatments or among sampling days within treatment. Cholesterol concentration was increased (p < 0.05) on the Control treatment throughout the experiment when compared to values of day 0. Dogs fed the FO treatment had higher plasma triglyceride and ghrelin concentrations than those fed the Control treatment. Body weight and food intake did not differ between dietary treatments. Faecal excretion was increased (p < 0.05) in the FO treatment. Dry matter digestibility was decreased (p < 0.05) and fat digestibility tended (p < 0.10) to decrease in the FO treatment. Overall, feeding a FO-containing diet showed a protective effect against the rise of plasma cholesterol and it increased plasma ghrelin concentration. However, FO supplementation did not appear to affect protein metabolism or postprandial glycaemia in adult lean dogs.     

Protective role of erdosteine on vancomycin-induced oxidative stress in rat liver

Drug-induced liver toxicity is a common cause of liver injury. This study was designed to elucidate whether high dose vancomycin (VCM) induces oxidative stress in liver and to investigate the protective effects of erdosteine, an expectorant agent. Twenty-two young Wistar rats were divided into three groups as follows: control group, VCM, and VCM plus erdosteine. VCM was administered intraperitoneally in the dosage of 200 mg/kg twice daily for 7 days. Erdosteine was administered orally administered once a day at a dose of 10 mg/kg body weight. The activities of antioxidant enzymes such as superoxide dismutase and catalase as well as the concentration of malondialdehyde, as an indicator of lipid peroxidation, were measured to evaluate oxidative stress in homogenates of the liver. VCM administration increased malondialdehyde levels (p < 0.001), superoxide dismutase (p < 0.01) and catalase (p < 0.001) activities. Erdosteine co-administration with VCM injections caused significantly decreased malondialdehyde levels (p < 0.001), superoxide dismutase (p < 0.01) and catalase (p < 0.001) activities in liver tissue when compared with VCM alone. It can be concluded that erdosteine may prevent VCM-induced oxidative changes in liver by reducing reactive oxygen species.     

24-hour Pattern in Lag Time of Response by Firemen to Calls for Urgent Medical Aid

The aim of the study was to assess the group 24-h pattern of lag time (LT) in response by regular and volunteer firemen (RFM and VFM) to calls for medical help (CFMH), specifically calls for out-of-hospital cardiac arrest (OHCA). LT, duration in min between a CFMH and departure of service vehicle equipped with a semiautomated defibrillator and generally staffed with four well-trained and ready-to-go FM, represents the integrated duration of several processes, each with separate reaction and decision-making times. The exact time of each CFHM (in min, h, day, month, yr) was recorded electronically, and the exact departure time from the station of the responding FM vehicle was recorded by an on-duty FM. Overall, CFMH made up 53?±?9% (SEM) of all emergencies calls for aid. To standardize the study methods, the reported findings are based on 568 CFMH specifically regarding OHCA that occurred during the 4-yr study span (January 2005 to December 2008). CFMH exhibited a 24-h pattern with a major peak at 10:00?h (mean?±?SEM: n?=?9.5?±?1.6) and major trough at 01:00?h (n?=?1.3?±?0.3; t test, p?<?.001). From year to year and season to season, a 24-h pattern was detected in the total of CFMH/h with two peaks (～10:00 and ～17:00h) and two troughs (～01:00 and ～15:00?h) (analysis of variance [ANOVA], p?<?.01; Cosinor, p?<?.05 to?<?.003), with neither season- nor year-related differences (χ², p?>?.05). In CFMH/h pooled time series, ANOVA-detected differences between the hourly means (p?<?.01), and Cosinor analysis validated a 24-h rhythm (p?<?.002). In raw data, the longest LT, indicative of poorest performance, occurred at 05:00?h (8.8?±?0.7?min) and the trough of LT, indicative of best performance, at 16:00?h (4.3?±?0.8?min (t test, p?<?.02). 24-h patterning in LT was validated both by ANOVA of hourly means (p?<?.0006) and Cosinor analysis (p?<?.05), with longest LT ～05:00?h and shortest LT ～16.00?h for data of the individual yearly time-series data. The 24-h LT rhythm was also validated in the pooled time series by Cosinor (p?<?.0001), with the 24-h mean?±?SEM?=?6?±?0.17?min and acrophase (peak) of 03:00?h?±?88?min (SD). Curve patterns of CFMH/h and LT/h differed widely. As a group phenomenon, the LT 24-h rhythm mimics the 24-h pattern of performance, as demonstrated by many laboratory and field investigations. The stability of the LT rhythm between years and seasons and its weak relationship with the CFMH 24-h pattern favors the hypothesis of an endogenous component or origin. The nighttime trough of performance is presumably linked to the elevated risk of work accidents in the same population of FM.