Melatonin reduces lung oxidative stress in patients with chronic obstructive pulmonary disease: a randomized, double-blind, placebo-controlled study

Abstract: Chronic obstructive pulmonary disease (COPD), a major cause of death and disability, is attributed to an abnormal inflammatory response by the lungs to noxious substances, primarily from cigarette smoke. Although oxidative stress is regarded as central to the pathogenesis of COPD, very few studies have examined the effects of antioxidants in this condition. This was a randomized, double‐blind, placebo‐controlled study on the effects of melatonin in COPD. Thirty‐six consecutive patients with clinically stable moderate to very severe COPD (30 men; mean ± S.D. = 66.6 ± 7.8 yr) were randomized to receive 3 mg melatonin (N = 18) or placebo for 3 months. Oxidative stress was evaluated by 8‐isoprostane levels in exhaled breath condensate at baseline (T0) and after one (T1), two (T2), and three months (T3) of treatment. Additionally, exhaled breath condensate levels of IL‐8, dyspnea severity (Medical Research Council scale), lung function (spirometry), and functional exercise capacity (six min walk test) were compared at baseline and after treatment. Patients receiving melatonin showed a decrease in 8‐isoprostane (T0: mean ± S.E.M. = 20.41 ± 2.92 pg/mL; T1: 18.56 ± 2.68 pg/mL; T2: 12.68 ± 2.04 pg/mL; T3: 12.70 ± 2.18 pg/mL; P = 0.04; repeated measures ANOVA) with significant differences from baseline after 2 (P = 0.03) and 3 months (P = 0.01). Dyspnea was improved by melatonin (P = 0.01), despite no significant changes in lung function or exercise capacity. Placebo‐treated patients, but not those who were given melatonin, showed an increase in IL‐8 (P = 0.03). In summary, melatonin administration reduced oxidative stress and improved dyspnea in COPD. Further studies are necessary to determine the potential role for melatonin in the long‐term management of these patients.     

Increased melatonin concentrations in children with growth hormone deficiency

A relationship between melatonin and growth hormone (GH) is poorly understood. We compare circadian melatonin rhythms in short children with normal and decreased GH secretion. The analysis included 22 children (20 boys and 2 girls) aged 11.1-16.9 yr (mean +/- S.E.M. = 14.1 +/- 0.3 yr) with short stature (height SDS below -2.0). Based on the GH peak in stimulation tests patients were divided into two groups: idiopathic short stature (ISS, n = 11; GH peak > or = 10 ng/mL) and GH deficiency (GHD, n = 11; GH peak < 10 ng/mL). In all patients the circadian melatonin rhythm was assessed on the basis of nine blood samples, collected in 4-hr intervals during the daytime and 2-hr intervals at night, with dark period lasting from 22:00 to 06:00 hr. Magnetic resonance imaging examination excluded organic abnormalities in central nervous system in all patients. Melatonin concentration at 24:00, 02:00 and 04:00 hr as well as the area under curve of melatonin concentrations (AUC) were significantly higher in the patients with GHD than in individuals with ISS. Significant correlations between GH secretion and melatonin concentrations at 24:00, 02:00 and 04:00 hr, and AUC were also observed. On the basis of these data it seems that the assessment of nocturnal melatonin secretion might be a valuable diagnostic tool used for the improvement of the difficult diagnosis of short stature in children.     

Clearance of melatonin and 6-sulfatoxymelatonin by hemodialysis in patients with end-stage renal disease

Patients with end-stage renal disease (ESRD) suffer from a number of related disorders. These include endocrine abnormalities, sleep disturbances, and depression. Melatonin is involved in the synchronization of exogenous zeitgebers with the endogenous rhythms, and it has effects on various psychological factors. As the concentrations of melatonin and the effects of dialysis have only occasionally been investigated in ESRD, we performed a study involving 35 patients, measuring the serum concentrations of melatonin, and of its major metabolite 6-sulfatoxymelatonin (aMT6s), before and after hemodialysis. Serum samples taken during morning hours from a control group (n=11) with intact kidneys served as controls. Patients were dialyzed for approximately 4 hr between 07:00 and 13:00 hr (S1), between 13:00 and 20:00 hr (S2), or between 18:30 and 22:30 hr (S3). Mean melatonin concentrations before hemodialysis were highly elevated when compared with the controls (40.6 vs. 6.7 pg/mL; P<0.001). Although melatonin levels were decreased to 20.3 pg/mL after dialysis, they were still well above the control levels. Likewise, aMT6s concentrations before dialysis were highly elevated in ESRD patients before dialysis when compared with controls (39.5 vs. 2.0 pg/mL; P<0.001), and also decreased by dialysis to levels still well above control levels (25.3 pg/mL). Clearance efficacy was better for melatonin (48.9%) than for aMT6s (36.6%; P<0.05). In ESRD patients, a diurnal rhythm for melatonin was observed (S1, 45.1 pg/mL; S2, 31.5 pg/mL; S3, 48.7 pg/mL; P<0.05), indicating that the normal synthesis rhythm is maintained. None of the following secondary disorders were correlated with melatonin concentrations: insomnia, delayed sleep onset, night-time arousals, and restless-leg syndrome. The reason for this observation is probably the melatonin concentrations, which were so high that no sub-classification could be identified. It is concluded that in ESRD patients, hemodialysis is unable to decrease elevated levels of melatonin and aMT6s to normal values. It is speculated that some of the secondary disorders in ESRD are caused by supraphysiological concentrations of melatonin.     

Evidence for melatonin synthesis in rodent Harderian gland: A dynamic in vitro study

ABSTRACT: Melatonin content and release from Harderian glands (HGs) has been measured by an in vitro perifusion technique in three rodent species: Wistar rat, Syrian hamster, and Siberian hamster. Melatonin immunoreactive concentrations in HGs of animals killed at 10.00 hr were 0.31 ± 0.031 pg/mg gland in male Wistar rat, 0.54 ± 0.026 pg/mg gland in male Siberian hamster, 0.17 ± 0.070 and 0.20 ± 0.059 pg/mg gland in male and female Syrian hamster, respectively. In all species examined, isolated HGs perifused for 9–15 hr released melatonin but did not stabilize their melatonin release rate. No sex-related difference could be noted in the HG melatonin release rate. The total amount of melatonin released over a 15 hr long perifusion was about 0.075 ± 0.004 ng/15 h/mg gland and 0.063 ± 0.010 ng/15 hr/mg gland in male and female Wistar rat, respectively; 0.155 ± 0.019 ng/15 hr/mg gland and 0.141 ± 0.006 ng/15 hr/mg gland in male and female Siberian hamster, respectively; 0.035 ± 0.003 ng/15 hr/mg gland and 0.045 ± 0.004 ng/15 hr/mg gland in male and female Syrian hamster, respectively. This amount, which is higher than the tissue levels, demonstrates the de novo melatonin synthesis. This is confirmed by the fact that infusion of the indoleamine precursor, tryptophan (TRP), stimulated melatonin secretion from HGs. The melatonin release is increased by 2.5-fold in male and female Wistar rat, 1.5-fold in male and female Siberian hamster, and 2.0- and 3.0-fold in male and female Syrian hamster, respectively. Treatment with a TRP hydroxylase inhibitor, para-chlorophenylalanine, reduced basal melatonin release and inhibited the TRP-induced melatonin stimulation. Kinetics and amounts of melatonin released were not affected by pinealectomy, ruling out a possible plasmatic origin of the HG melatonin. Isoproterenol, a β-adrenergic agonist, and dibutyryl cyclic AMP, a cyclic AMP analogue, failed to stimulate HG melatonin secretion. In conclusion, these results confirm the presence of melatonin in the HGs and demonstrate that melatonin is synthesized in and released from isolated rodent HGs.     

Tripterygium glycosides suppress production of interleukin‐4 by splenocytes in oxazolone‐induced murine colitis

OBJECTIVE: To investigate the in vitro effect of Tripterygium glycosides (TG) on cytokine production by splenocytes in oxazolone (OXZ)‐induced colitis in mice. METHODS: Oxazolone (6 mg in 50% ethanol) was administered to male SJL/J mice intrarectally to induce colitis and the mice were killed 3 days later. Isolated splenocytes were cultured for 24 h in the presence of phorbol myristate acetate and ionomycin. A preparation of Tripterygium glycosides at a concentration of either 0.1 mg/mL or 0.01 mg/mL was added to the culture medium of splenocytes. Production of interferon gamma (IFN‐γ) and interleukin‐4 (IL‐4) in the supernatant were measured by ELISA. RESULTS: Production of IFN‐γ in the normal control group was suppressed by TG at both concentrations (0.01 and 0.1 mg/mL; 1.24 ± 0.13 pg/mL (samples without TG) → 0.97 ± 0.26 pg/mL (0.01 mg/mL TG) → 0.87 ± 0.18 pg/mL (0.1 mg/mL TG); P < 0.02) in a dose dependent manner. In the OXZ‐induced colitis group, the basic level of IFN‐γ was significantly lower than that of the normal control group (1.24 ± 0.13 pg/mL vs 0.65 ± 0.08 pg/mL; P < 0.01); but IL‐4 production was significantly increased in the OXZ‐induced colitis without TG group (7.83 ± 0.69 pg/mL vs 5.65 ± 0.48 pg/mL, P < 0.01). In both groups, TG suppressed IL‐4 production in a dose‐dependent manner (normal control group: 5.65 ± 0.48 pg/mL (samples without TG) → 4.97 ± 0.38 pg/mL (0.01 mg/mL TG) → 3.98 ± 0.32 pg/mL (0.1 mg/mL TG), P < 0.01; OXZ group: 7.83 ± 0.69 pg/mL (samples without TG) → 7.07 ± 0.47 pg/mL (0.01 mg/mL TG) → 6.35 ± 0.48 pg/mL (0.1 mg/mL TG), P < 0.01). CONCLUSION: Oxazalone‐induced IL‐4 overproduction by splenocytes was significantly suppressed by TG in a dose dependent manner and the beneficial effects of TG on ulcerative colitis might be related to the suppression of the Th2 type (e.g. IL‐4) mediated immunological response of splenocytes.     

Effects of a one-hour light pulse on the timing of the circadian rhythm in melatonin secretion in rams

Abstract: The effects of a 1-hr light pulse on the timing of the circadian rhythm in the blood plasma concentration of melatonin were documented in Soay rams. Groups of 5 to 6 animals were transferred from short days (LD 8: 16) to constant dim red light (DD) for 6 days, and were exposed to a 1-hr light pulse at one of 16 different times throughout 24 hr on day 3. Blood samples were collected hourly for 30 hr before (day 2–3) and after the light pulse (day 5–6), and the plasma concentrations of melatonin were measured by radioimmunoassay. The animals were allocated to experimental groups based on the circadian time (CT) when the light pulse was given using two hourly blocks through the circadian day; the onset of enhanced melatonin secretion (melatonin peak) was designated as CT 12. Under DD there was a clearly defined plasma melatonin rhythm in all animals. The mean duration of the melatonin peak was 13.24 ± 0.16 hr (n = 91) and the mean period between the onset of successive melatonin peaks was 23.55 ± 0.10 hr (n = 21). The effect of the 1-hr light pulse on the time of onset of the melatonin peak varied significantly with the circadian time when the light pulse was given (ANOVA, P= 0.031). Light-induced significant (pre- vs post-pulse onset, Students t-test, P < 0.05) phase delays in the onset of the melatonin peak in the early subjective day at CT 2.5 hrs (mean ø: -1.9 hr), and in the early subjective night at CT 12.5 and 14.5 (mean ø: -2.0 hrs), but not at other times. The light pulse never induced significant phase advances. The effects of the light pulse on the offset of plasma melatonin peak did not vary significantly with the time of the light pulse (ANOVA, P= 0.780), although significant differences in the pre- and post-pulse offset occurred at CT 14.5 and 18.5 (mean ø: -1.5 hr). The differential changes in the onset and the offset of the melatonin peak resulted in changes in the duration of the peak (maximum difference between means: 3.8 hr). The results indicate that entrainment occurs under natural 24 hr LD cycles when light impinges on the early subjective night and induces a net phase delay, thus extending the period of the melatonin rhythm to 24 hr. This causes a close phase relationship between the end of the light period and the onset of the melatonin peak as occurs in sheep under natural cycles. The results are also consistent with a multiple oscillator governing melatonin secretion, and that differential entrainment of the component oscillators by light affects the duration of the melatonin peak.     

Nocturnal melatonin and luteinizing hormone rhythms in women with hyperprolactinemic amenorrhea

Abstract: To examine the role of melatonin in pathological hyperprolactinemia we compared untreated young females (N = 5) with hyperprolactinemic amenorrhea owing to pituitary microadenoma to healthy female controls (N = 6). Serum samples for melatonin, prolactin, and luteinizing hormone (LH) concentrations were obtained every 15 min from 1900 hr to 0700 hr in a controlled light-dark environment with simultaneous sleep recordings. The mean (±SD) light-time period, dark-time period, and the integrated nocturnal melatonin secretion values (area under the curve, or AUC) in patients (51 ± 11 pmol/L, 157 ± 33 pmol/L, and 102 ± 19 pmol/min-L × 10³, respectively) were similar to the values obtained in controls (79 ± 39, 165 ± 44, 111 ± 31, respectively). The onset of the nocturnal melatonin rise, peak level, and peak time were similar in the two groups. A significant nocturnal prolactin rise was observed in patients (112 ± 9 vs. 65 ± 11 μg/L, P < 0.006) and controls (19 ± 2 vs. 10 ± 3 μg/L, P < 0.006). The time of prolactin peak was similar in patients and controls (0424 ± 3: 36 vs. 0350 ± 2: 21) and paralleled that of melatonin (0354 ± 1: 46 vs. 0337 ± 1: 30). The mean ± SD light-time period, dark-time period, and the AUC values of LH were similar in patients and controls. The number of LH pulses in patients (7.2 ±1.9 per 12 hr) were not different from those in controls (7.7 ±2.1). The LH pulse interval was 100 ± 22 min in patients compared with 94 ± 23 min in controls. The mean (±SD) nocturnal estradiol (E2) levels were significantly lower in patients (84 ±15 pmol/L) than in controls (224 ± 77) (P < 0.005). Analysis of LH and melatonin secretory profiles revealed significant pulses for both hormones. No significant relationship was observed between the LH and melatonin pulses. However, a negative correlation between LH pulse amplitude and the number of melatonin pulses (P < 0.04) and a positive correlation between LH amplitude and duration of melatonin pulses (P < 0.04) were observed. Taken together, these data suggest that the suppression of normal ovarian cycles in women with hyperprolactinemic amenorrhea owing to pituitary microadenoma may be mediated by blocking of gonadotropin action by prolactin at the ovarian level; yet it remains possible that chronically elevated prolactin might prevent the LH surge and thus lead to amenorrhea. Pulsatile melatonin secretion is unaltered in these patients, and the frequent occurrence of amenorrhea in this population is not mediated by melatonin.     

Melatonin pharmacokinetics following two different oral surge-sustained release doses in older adults

Abstract: Melatonin is increasingly used for the treatment of sleep disorders. Surge‐sustained formulations consisting of combined immediate release and controlled release dosing may mimic the endogenous melatonin physiologic profile. However, relatively little is known about the pharmacokinetic properties of low‐dose (<0.5 mg) and high‐dose (>2 mg) melatonin in a combined immediate release/controlled release dose, especially in older adults who may also exhibit altered melatonin disposition. To assess this, we conducted a randomized, double‐blind, placebo‐controlled study of low‐dose (0.4 mg) and high‐dose (4.0 mg) melatonin (25% immediate release + 75% controlled release) in 27 older adults with insomnia complaints and low endogenous melatonin levels to determine whether melatonin pharmacokinetic properties differ between these two doses. The time to maximum level (1.3 hrs versus 1.5 hrs), elimination half‐life (1.8 hrs versus 2.1 hrs), and apparent total clearance (379 L/hr versus 478 L/hr) did not differ significantly between the low‐ and high‐dose arms, respectively. The maximum concentration was 405 ± 93 pg/mL for the low‐dose arm and 3999 ± 700 pg/mL for the high‐dose arm, both of which are substantially higher than physiologic melatonin levels for this age group. In addition, subjects in the high‐dose arm maintained melatonin levels >50 pg/mL for an average of 10 hrs, which could result in elevated melatonin levels beyond the typical sleep period. Renal and liver function parameters remained stable after 6 wks of treatment. The linear pharmacokinetic behavior of melatonin observed in the elderly can form the basis for future studies exploring a wider range of dosing scenarios to establish exposure–response relationships for melatonin‐mediated sleep outcomes.     

Frequent red cell transfusions reduced vascular endothelial activation and thrombogenicity in children with sickle cell anemia and high stroke risk

Stroke is one of the most disabling complications of sickle cell anemia (SCA). The molecular mechanisms leading to stroke in SCA or by which packed red blood cell (PRBC) transfusion prevents strokes are not understood. We investigated the effects of PRBC transfusion on serum biomarkers in children with SCA who were at high‐risk for stroke. Serum samples from 80 subjects were analyzed, including baseline, study exit time point and 1 year after study exit. Forty of the 80 samples were from subjects randomized to standard care and 40 from transfusion arm. Samples were assayed for levels of BDNF, sVCAM‐1, sICAM‐1, MPO, Cathepsin‐D, PDGF‐AA, PDGF‐AB/BB, RANTES (CCL5), tPAI‐1, and NCAM‐1 using antibody immobilized bead assay. Significantly lower mean serum levels of sVCAM‐1 (2.2 × 10⁶ ± 0.8 × 10⁶ pg/mL vs. 3.1 × 10⁶ ± 0.9 × 10⁶ pg/mL, P < 0.0001), Cathepsin‐D (0.5 × 10⁶ ± 0.1 × 10⁶ pg/mL vs. 0.7 × 10⁶ ± 0.2 × 10⁶ pg/mL, P < 0.0001), PDGF‐AA (10556 ± 4033 pg/mL vs. 14173 ± 4631 pg/mL, P = 0.0008), RANTES (0.1 × 10⁶ ± 0.07 × 10⁶ pg/mL vs. 0.2 × 10⁶ ± 0.06 × 10⁶ pg/mL, P < 0.006), and NCAM‐1 (0.7 × 10⁶ ± 0.2 × 10⁶ pg/mL vs. 0.8 × 10⁶ ± 0.1 × 10⁶ pg/mL, P < 0.0006) were observed among participants who received PRBC transfusion, compared to those who received standard care. Twenty or more PRBC transfusion over 4 years was associated with lower serum levels of sVCAM‐1 (P < 0.001), PDGF‐AA (P = 0.025), and RANTES (P = 0.048). Low baseline level of BDNF (P = 0.025), sVCAM‐1 (P = 0.025), PDGF‐AA (P = 0.01), t‐PAI‐1 (P = 0.025) and sICAM‐1 (P = 0.022) was associated with higher probability of stroke free survival. Beyond improving hemoglobin levels, our results suggest that the protective effects of PRBC transfusion on reducing stroke in SCD may result from reduced thrombogenesis and vascular remodeling. Am. J. Hematol. 89:47–51, 2014. © 2013 Wiley Periodicals, Inc.     

Pharmacokinetics of orally administered melatonin in critically ill patients

Abstract: Critically ill patients exhibit reduced melatonin secretion, both in nocturnal peaks and basal daytime levels. Oral melatonin supplementation may be useful for known sedative and antioxidant properties. Its early enteral absorption and daily pharmacokinetics were determined in two cohorts of six high‐risk patients in this prospective trial. During their third and fourth Intensive Care Unit (ICU) day, they underwent two different sets of repeated blood samples to detect serum melatonin levels through radio‐immuno‐assay. Cohort 1: samples taken at 20:00, 20:45, 21:30, 24:00, 03:00, 06:00, 14:00, 20:00 to describe the daily pharmacokinetics. Cohort 2: 20:00, 20:05, 20:10, 20:20, 20:30, 20:45 to study the early absorption. On ICU day 3, endogenous levels were measured, while the absorption of exogenous melatonin was determined on ICU day 4 after administration, at 20:00, of 3 mg melatonin. All basal levels were below the expected values. Following enteral administration, pharmacological levels were already reached in 5 min, with a serum peak after 16 min (half‐absorption time: 3 min 17 s). The maximum serum level observed was 11040 pg/mL and the disappearance rate indicated a half‐elimination time of 1 hr 34 min. Serum melatonin levels decreased significantly after midnight; pharmacological levels were maintained up to 10 hr following administration. No excessive sleepiness was reported in this patient group. Critically ill patients exhibited reduced melatonin secretion, as reported in the literature. Despite the critical illness, the oral bioavailability was satisfactory: serum levels after oral administration showed basically unchanged intestinal absorption, while disappearance rate was slower than reported elsewhere in healthy volunteers.     

Light/dark patterns of soluble vascular cell adhesion molecule-1 in relation to melatonin in patients with ST-segment elevation myocardial infarction

Elevated levels of soluble cellular adhesion molecules have been reported in patients with acute coronary syndromes. Likewise, a relation between decreased nocturnal melatonin levels and coronary artery disease has been suggested. The aim of the present study was to investigate the day-night variations in the concentration of soluble vascular cell adhesion molecule-1 (sVCAM-1) in patients with ST-segment elevation myocardial infarction (STEMI) in relation to the light/dark melatonin pattern. Ninety consecutive patients with STEMI who were admitted to the Coronary Care Unit of our institution were studied. We also recruited 70 age- and gender-matched healthy normal subjects. Blood samples were drawn at 09:00 and 02:00 hr, while patients were at rest, for the assessment of sVCAM-1 and melatonin, which were measured using commercially available ELISA. In STEMI patients, melatonin concentrations maintained a diurnal variation, but the difference between nocturnal and diurnal levels was less than that in healthy subjects (P < 0.0001). In contrast to findings with melatonin, sVCAM-1 levels showed no diurnal variations in control subjects. In the STEMI group, however, sVCAM-1 concentration at 02:00 hr was significantly higher than that during the light phase (09:00 hr; 1391 +/- 38 versus 1200 +/- 43 ng/mL, P < 0.05). The results suggest that diurnal variations in endogenous sVCAM-1 production in STEMI patients might be related to an attenuated circadian secretion of melatonin.     

Long‐term effects of maternal separation on the responsiveness of the circadian system to melatonin in the diurnal nonhuman primate (Macaca mulatta)

Depression is often linked to early‐life adversity and circadian disturbances. Here, we assessed the long‐term impact of early‐life adversity, particularly preweaning mother–infant separation, on the circadian system's responsiveness to a time giver or synchronizer (Zeitgeber). Mother‐reared (MR) and peer‐reared (PR) rhesus monkeys were subjected to chronic jet‐lag, a forced desynchrony protocol of 22 hr T‐cycles [11:11 hr light:dark (LD) cycles] to destabilize the central circadian organization. MR and PR monkeys subjected to the T‐cycles showed split locomotor activity rhythms with periods of ~22 hr (entrained) and ~24 hr (free‐running), simultaneously. Continuous melatonin treatment in the drinking water (20 μg/mL) gradually increased the amplitude of the entrained rhythm at the expense of the free‐running rhythm, reaching complete entrainment by 1 wk. Upon release into constant dim light, a rearing effect on anticipation for both the predicted light onset and food presentation was observed. In MR monkeys, melatonin did not affect the amplitude of anticipatory behavior. Interestingly, however, PR macaques showed light onset and food anticipatory activities in response to melatonin treatment. These results demonstrate for the first time a rearing‐dependent effect of maternal separation in macaques, imprinting long‐term plastic changes on the circadian system well into late adulthood. These effects could be counteracted by the synchronizer molecule melatonin. We conclude that the melatonergic system is targeted by early‐life adversity of maternal separation and that melatonin supplementation ameliorates the negative impact of stress on the circadian system.     

Evidence for a circadian rhythm of insulin release from perifused rat pancreatic islets

Summary This study aims to analyse a circadian rhythm of insulin secretion from isolated rat pancreatic islets in vitro and its potential modulation by melatonin, the concentrations of which change in vivo inversely to that of insulin. The circadian rhythm was evaluated in a perifusion system, adapted to the specific conditions of pancreatic islets. To determine rhythmicity of insulin secretion, 30-min fractions were collected continuously for investigative periods of 44 to 112 h. Insulin secretion in 10 experiments was analysed by using the MacAnova-program for period length (τ), the χ²-periodogram for test of significance (p < 0.001), and additionally the empirical cosine adaptation for amplitude and goodness-of-fit. Thereby a circadian pattern was observed with periods (τ) between 21.8 and 26.2 h. The period duration (mean ± SEM) was 23.59 ± 0.503 h, the overall mean insulin release 1038 ± 13 pmol/l and the mean amplitude 88 ± 17 pmol/l. Adding melatonin (10 nmol/l, t = 2 h) as a hormonal Zeitgeber during analysis of circadian insulin secretion phase-response studies show phase-shifts with approximately 9 h phase advance. Thereafter the circadian period was maintained, while the amplitude was enhanced. From this it is concluded that an endogenous circadian oscillator is located within the pancreatic islets of the rat that regulates circadian insulin secretion of the insulin-producing beta cells. The pacemaker is remarkably stable, because its periodicity is not affected by factors altering insulin secretion. In agreement with inhibitory influences of melatonin (range 0.5 nmol/l to 5 μmol/l) on the insulin response in vitro, the phase-responses support the contention that pancreatic beta cells may be targets for melatonin action. [Diabetologia (1998) 42: 1085–1092] Received: 11 December 1997 and in final revised form: 20 March 1998     

Functional MICA-129 polymorphism and serum levels of soluble MICA are correlated with ulcerative colitis in Chinese patients

Background and Aim: The aim of the present study was to evaluate the contribution of the dimorphism (MICA‐129 val and met) to the genetic susceptibility and functions of ulcerative colitis (UC) in patients in central China. Methods: Genotyping of MICA‐129 was performed in 272 consecutive UC patients and 560 age‐ and sex‐matched healthy individuals by using a polymerase chain reaction‐sequencing based typing (PCR‐SBT) method. A total of 93 patients and 98 healthy individuals serum soluble MICA (sMICA) concentrations were detected by enzyme‐linked immunosorbent assay. Results: Both the frequencies of the variant allele (val) and genotype (val/val) in the MICA‐129 gene were significantly higher in UC patients than in the controls (77.4% vs 71.7%, P = 0.015, 95% confidence interval [CI]: 1.064–1.716; 56.9% vs 46.4%, P = 0.005, 95% CI: 1.142–2.047). Serum sMICA levels were significantly higher in UC patients than in the controls (560 ± 140 pg/mL vs 157 ± 67 pg/mL, P < 0.0001). The genotype also affected the extent and the activity of UC. Furthermore, patients with the MICA‐129 val/val genotype had higher serum sMICA levels than those with the val/met + met/met genotype (661 ± 352 SD pg/mL vs 523 ± 245 SD pg/mL, 95% CI: 13.47–265.35, P = 0.03). In addition, patients with severe colitis were more susceptible to higher levels of sMICA than those with mild colitis. Conclusions: Our findings showed that the MICA‐129 gene polymorphism as a functionally relevant gene was associated with UC and seems to play a potential role in the development of UC in patients in central China.     

Circadian secretion patterns of melatonin after major surgery

Abstract: Biorhythms, such as regular variation in core body temperature and the pattern of the secretion of melatonin, are thought to be mediated by the same biological clock. Core body temperature is affected by the inflammatory response to major surgery. Apart from the well-known inhibitory effect of bright light on its secretion, melatonin is an exceedingly good marker of one of the central generating systems of circadian rhythms. We sequentially measured the plasma melatonin concentration pattern in patients who had undergone esophagectomy with thoracotomy to elucidate the circadian rhythm after major surgery. From seven patients who had received esophagectomy with thoracotomy for esophageal cancer, plasma concentrations of melatonin were measured using an RIA method. Blood samples were collected via each patient's arterial line at 00.00, 02.00, 04.00, 06.00, 08.00, 12.00, 16.00, 20.00, and 24.00 hr on the first postoperative day for six of the patients, and, for one patient, every 2 hr until the third postoperative day and every 4 hr thereafter until the sixth postoperative day. Four patients out of seven had melatonin concentrations of over 30 pg/ml (mean 34 pg/ml) at 24.00 hr on the first postoperative day. Five patients showed circadian secretion patterns of melatonin during the first postoperative day. One patient whose melatonin concentrations were measured consecutively for 6 days showed a regular circadian secretion pattern through the 6 days of the study. Even the stress caused by extremely invasive surgery did not significantly disturb the melatonin secretion pattern.     

Prevention of ischemia/reperfusion-induced cardiac apoptosis and injury by melatonin is independent of glutathione peroxdiase 1

Abstract: Free‐radical generation is one of the primary causes of myocardial ischemia/reperfusion (I/R) injury. Melatonin is an efficient free‐radical scavenger and induces the expression of antioxidant enzymes. We have previously shown that melatonin can prevent free‐radical‐induced myocardial injury. To date, the mechanism underlying melatonin’s cardioprotective effect is not clear. In this study, we assessed the ability of melatonin to protect against I/R injury in mice deficient in glutathione peroxidase 1 (Gpx1). Mice hearts were subjected to 40 min of global ischemia in vitro followed by 45 min of reperfusion. Myocardial I/R injury (expressed as % of recovery of left ventricular developed pressure × heart rate) was exacerbated in mice deficient in Gpx1 (51 ± 3% for Gpx1^+/+ mice versus 31 ± 6% for Gpx1^?/? mice, P < 0.05). Administration of melatonin for 30 min protected against I/R injury in both Gpx1^+/+ mice (72 ± 4.8%) and Gpx1^?/? mice (63 ± 4.7%). This protection was accompanied by a significant improvement in left ventricular end‐diastolic pressure and a twofold decrease in lactate dehydrogenase (LDH) level released from melatonin‐treated hearts. In another set of experiments, mice were subjected to 50 min of ligation of the left descending anterior coronary artery in vivo followed by 4 hr of reperfusion. The infarct sizes, expressed as the percentage of the area at risk, were significantly larger in Gpx1^?/? mice than in Gpx1^+/+ mice (75 ± 9% versus 54 ± 6%, P < 0.05) and were reduced significantly in melatonin‐treated mice (31 ± 3.7% Gpx1^?/? mice and 33 ± 6.0% Gpx1^+/+ mice). In hearts subjected to 30 min of coronary artery occlusion followed by 3 hr of reperfusion, melatonin‐treated hearts had significantly fewer in situ oligo ligation‐positive myocytes and less protein nitration. Our results demonstrate that the cardioprotective function of melatonin is independent of Gpx1.     

Circulating interleukin-27 levels in Helicobacter pylori-infected patients with gastric or duodenal ulcers, independent of the bacterial cytotoxin-associated gene A virulence factor

OBJECTIVE: The aim was to evaluate the interleukin (IL)‐27 levels in Helicobacter pylori (H. pylori)‐infected patients with gastric ulcer (GU) or duodenal ulcer (DU) and to determine its association with H. pylori virulence factor cytotoxin‐associated gene A (CagA). METHODS: In all, 127 H. pylori infected patients (including 96 DU patients, of whom 61 were anti‐CagA⁺ and 35 were anti‐CagA^‐) and 31 GU patients (of whom 15 were anti‐CagA⁺ and 16 were anti‐CagA^‐), 60 asymptomatic (AS) carriers (of whom 30 were anti‐CagA⁺ and 30 were anti‐CagA^‐) and 30 healthy H. pylori‐negative participants (as a control) were enrolled in the study. Serum concentrations of IL‐27 were measured by the enzyme‐linked immunosorbent assay method. RESULTS: The mean levels of IL‐27 in the GU (44.26 ± 7.12 pg/mL) and DU patients (40.84 ± 3.90 pg/mL) was significantly higher than those observed in the AS carriers (22.06 ± 1.90 pg/mL, P < 0.001) and the control group (18.12 ± 1.68 pg/mL, P < 0.001 and P < 0.002, respectively). In the GU, DU and AS groups the levels of IL‐27 in anti‐CagA⁺ participants were not significantly differ from that in the anti‐CagA^‐ participants. CONCLUSIONS: These results showed that the mean concentration of IL‐27 in H. pylori‐infected peptic ulcer (PU) patients was higher than in AS carriers and the healthy control group. The serum concentrations of IL‐27 were not affected by the CagA factor.     

Reduction of Plasma Levels of Soluble Tumor Necrosis Factor and Interleukin‐2 Receptors by Means of a Novel Immunoadsorption Column

This non‐randomized open clinical study investigated the safety and efficacy of extracorporeal fractionated plasma adsorption using the Oncosorb immune adsorption column. The column selectively bound soluble tumor necrosis factor receptors 1 and 2 (sTNF‐R1 and sTNF‐R2) and soluble interleukin‐2 receptors (sIL2‐R) by lowering plasma levels in patients with metastatic cancer. Nine patients (three men and six women; mean age 48 years, aged 41–68 years) with metastatic cancer received at least 12 immune adsorption procedures. Thrice‐weekly immune adsorption separated a low molecular weight (150 000 D) plasma fraction from the patients' blood, passing the plasma fraction through the column in an extracorporeal plasma perfusion circuit. Respective plasma receptor mean concentrations before and after 167 procedures were: sTNF‐R1: 1936 ± 788 pg/mL before treatment vs. 1312 ± 989 pg/mL after treatment; sTNF‐R2: 3140 ± 1173 pg/mL before treatment vs. 1816 ± 1 ± 1677 pg/mL after treatment (P < 0.01 for each inhibitor). Mean reductions in sTNF‐R1 (48%), sTNF‐R2 (55%), and sIL2‐R levels (72%) were observed for treatments 3–12 (P < 0.001). Clinical findings indicated tumor inflammation and necrosis in most patients. Side‐effects were low‐grade fever, flu‐like symptoms; tumor pain and redness, warmth, tenderness, and edema. The column demonstrated safety and efficacy in lowering plasma sTNF‐R1, sTNF‐R2, and sIL2‐R levels. Minor clinical adverse effects common to the use of extracorporeal devices were seen.     

Reduction in circulating markers of endothelial dysfunction in HIV-infected patients during antiretroviral therapy

Objectives

Antiretroviral therapy (ART) in HIV‐infected patients is associated with increased cardiovascular risk. Circulating markers of endothelial dysfunction may be used to study early atherogenesis. The aim of our study was to investigate changes in such markers during initiation of ART.

Methods

In 115 HIV‐positive treatment‐naïve patients, plasma lipids, E‐selectin, soluble intercellular adhesion molecule 1 (sICAM‐1), soluble vascular cell adhesion molecule 1 (sVCAM‐1), tissue‐type plasminogen activator inhibitor 1 (tPAI‐1) and high‐sensitivity C‐reactive protein (hsCRP) were measured before and after 2 and 14 months of ART. A control group of 30 healthy subjects was included. Values are mean±standard error of the mean.

Results

Prior to treatment, HIV‐infected patients had elevated levels of sICAM‐1 (296±24 vs. 144±12 ng/mL), tPAI‐1 (18 473±1399 vs. 5490±576 pg/mL) and hsCRP (28 060±5530 vs. 6665±2063 ng/mL) compared with controls (P<0.001). In contrast, sVCAM‐1 and E‐selectin did not differ between the groups. Initiation of ART resulted in significantly lower levels of E‐selectin (15.1±0.8; P<0.01), sICAM‐1 (248±12 ng/mL; P<0.05), sVCAM‐1 (766±33 ng/mL; P<0.001) and hsCRP (14 708±2358 ng/mL; P<0.001) after 2 months, which remained reduced at 14 months. tPAI‐1 was not influenced by initiation of ART.

Conclusions

Markers of endothelial dysfunction were elevated in treatment‐naïve HIV‐infected patients and were related to HIV RNA viral load. Initiation of ART reduced the levels of the majority of these markers. The positive effect of ART initiation was dependent on the duration of HIV infection prior to treatment.     

The use of high-dose melatonin in liver resection is safe: first clinical experience

Abstract: Experimental data suggest that melatonin decreases inflammatory changes after major liver resection, thus positively influencing the postoperative course. To assess the safety of a preoperative single dose of melatonin in patients undergoing major liver resection, a randomized controlled double‐blind pilot clinical trial with two parallel study arms was designed at the Department of General and Transplantation Surgery, Ruprecht‐Karls‐University, Heidelberg. A total of 307 patients, who were referred for liver surgery, were screened. One hundred and thirteen patients, for whom a major liver resection (≥3 segments) was scheduled, were eligible. Sixty‐three eligible patients refused to participate, and therefore, 50 patients were randomized. A preoperative single dose of melatonin (50 mg/kg BW) dissolved in 250 mL of milk was administered through the gastric tube after the intubation for general anesthesia. Controls were given the same amount of microcrystalline cellulose. Primary endpoint was safety. Secondary endpoints were postoperative complications. Melatonin was effectively absorbed with serum concentrations of 1142.8 ± 7.2 ng/mL (mean ± S.E.M.) versus 0.3 ± 7.8 ng/mL in controls (P < 0.0001). Melatonin treatment resulted in lower postoperative transaminases over the study period (P = 0.6). There was no serious adverse event in patients after melatonin treatment. A total of three infectious complications occurred in either group. A total of eight noninfectious complications occurred in five control patients, whereas three noninfectious complications occurred in three patients receiving preoperative melatonin (P = 0.3). There was a trend toward shorter ICU stay and total hospital stay after melatonin treatment. Therefore, a single preoperative enteral dose of melatonin is effectively absorbed and is safe and well tolerated in patients undergoing major liver surgery.