bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Pinealectomy, Eye Enucleation, and Melatonin Treatment on Ovarian Activity and Vitellogenin Levels in the Catfish Exposed to Short Photoperiod or Long Photoperiod
Authors: Garg S.K.
Published: February 2007

To investigate the relative importance of pineal, and eyes, and melatonin treatment on ovarian activity, catfish, Heteropneustes fossilis subjected to pinealectomy, eye nucleation, or both were exposed to short (LD 9:15) or long (LD 14:10) photoperiod during the different stages of the annual reproductive cycle. During the preparatory period, pinealectomy accelerated ovarian recrudescence under long photoperiod, but no effects of pinealectomy were observed under short photoperiod. Pineal has no influence on ovarian activity during the preplanning and spawning periods of the reproductive cycle. In the late postspawning period, ovarian recrudescence is accelerated after pinealectomy in catfish maintained under short photoperiod (LD 9:15 at 25°C). But under long photoperiod (LD 14:10 at 25°C), pinealectomy delayed ovarian recrudescence. An investigation into the role of the eyes revealed that eye enucleation nullifies the inhibitory effects of LD 9:15 and represses the stimulatory effects of LD 14:10. Combined surgery inhibited ovarian development under both the regimes. It is significant that pinealectomy and/or blinding neither counteracted nor delayed the post spawning ovarian regression. The findings suggest that the role of the pineal in catfish reproduction is variable and depends upon the photoperiod to which they are exposed as well as on the time of the year and the stage of the reproductive cycle. It is concluded that extra retinal and extra pineal photoreceptors also are involved in influencing seasonal reproduction. Further, no effects of melanoma treatment on ovarian activity or on vitellogenin levels during the preparatory or preplanning periods were observed, indicating that the pineal effects on gondola activity in catfish may not be mediated through the secretion of melatonin.
Fluctuation of Blood Melatonin Concentrations With Age: Result of Changes in Pineal Melatonin Secretion, Body Growth, and Aging
Authors: Pang S. F. , Tsang C. W. , Hong G. X. , Yip P. C. Y. , Tang P. L. , Brown G. M.
Published: February 2007

Melatonin in the systemic circulation of rats fluctuates with age, and the causes for such changes were investigated. Male rats (aged 7 days, 16 days, 18 days, 20 days, 30 days, 48 days, 60 days, and > 17 months) were adapted under a lighting regime of 12L: 12D for at least 7 days. Pineals and blood samples from the trunk or confluens sinuum were collected in the dark period. Melatonin in tissues was extracted, identified, and determined by gas chromatography‐mass spectrometry (GC‐MS) and/or radioimmunoassay. Tissue melatonin levels obtained by radioimmunoassay correlated closely with those quantified by GC‐MS. Thus, the melatonin radioimmunoassay used is a reliable assay method for melatonin in the plasma and pineal of the rat.

Plasma melatonin in the confluens sinuum of rats exhibited episodic release superimposed on a basal release pattern. It was suggested that there are two pools of melatonin in the pineal gland, a readily releasable pool and a bound pool. The mean plasma levels of melatonin in the confluens sinuum of rats increased with age with the highest level recorded at 60 days old and declined to a lower level at > 17 months old. The above age‐related changes, being similar to the alterations in pineal melatonin levels with growth and aging, suggest that, under our experimental conditions, levels of pineal melatonin increase or decrease with its secretory rate.

In developing rats, the age‐related increase in the rate of secretion of pineal melatonin as reflected by increases in melatonin levels in the confluens sinuum or pineal melatonin content before adulthood is different from the changes in melatonin levels in the systemic circulation which showed an early developmental rise, followed by an active period and then a prepubertal decline. However, when the body weight was taken into consideration, changes in the levels of pineal melatonin content per 100 gm body weight or the calculated blood melatonin levels (plasma melatonin in the confluens sinuum/body:head ratio) correlated well with the fluctuation of serum melatonin in the systemic circulation. Thus, the developmental changes in the concentrations of melatonin in the general circulation are the result of 1) changes in the rate of pineal melatonin secretion and 2) increase in the dilution factor because of increase in body size. In old rats, levels of plasma melatonin in the confluens sinuum and pineal melatonin content decreased indicating a decline in the rate of pineal melatonin secretion. These results suggest that the reduced level of systemic melatonin in aged rats is the result of a decline in the rate of pineal melatonin secretion plus an increase in the body weight.
Preliminary Studies on Melatonin in the Treatment of Myelodysplastic Syndromes Following Cancer Chemotherapy
Authors: Viviani S. , Negretti E. , Orazi A. , Sozzi G. , Santoro A. , Lissoni P. , Esposti G. , Fraschini F.
Published: February 2007

Experimental studies have suggested that the pineal hormone melatonin, in addition to its documented antineoplastic action, plays a role in the physiological regulation of blood cell proliferation. Based on these data, we evaluated the clinical effects of melatonin therapy in patients with myelodysplastic syndrome (MDS) secondary to cancer chemotherapy for primary neoplasms. The study was carried out on six patients, and melatonin was given orally at a dose of 20 mg/daily, following a schedule prepared to reproduce the circadian rhythm of the pineal hormone. A transient improvement in platelet and neutrophil count was achieved in two of five patients with thrombocytopenia and in two of four patients with neutropenia before therapy, respectively, while no effect was seen on hemoglobin concentration. Mean survival time was 12.5 months, and a long survival, greater than 30 months, was achieved in two of six patients. These preliminary results seem to suggest that melatonin may have a role in the treatment of MDS induced by previous cancer chemotherapy.
Effect of a 15 minute light pulse on nocturnal serum melatonin levels in human volunteers
Authors: Petterborg L. J. , Kjellman B. F. , Thalén B. E. , Wetterberg L.
Published: February 2007

Petterborg LJ, Kjellman BF, ThalQ BE, Wetterberg L. Effect of a 15‐minute light pulse on nocturnal serum melatonin levels in human volunteers. J Pineal Res 1991:10:9‐13.

Monitoring the daily melatonin rhythm during the course of phototherapy for affective disorders may be beneficial in assessing the efficacy of such treatments. It is therefore of interest to study the effects of the timing, duration, and intensity of bright light pulses on melatonin levels in normal subjects. To examine the effects of a single exposure to a brief burst of bright light on serum melatonin, groups of healthy human volunteers of both sexes were treated with a 15 minute pulse of bright light (350 cd/m2) early in the evening during the winter months. Serial blood samples were collected from each person and the effect of the light pulse on serum melatonin and cortisol levels determined.

Melatonin levels were significantly but only transiently suppressed by the light pulse, while cortisol levels were not affected. These results demonstrate that short duration bright light treatments can influence the melatonin rhythm generating system in humans.
Inhibition of human platelet aggregation and thromboxane B2 production by melatonin. Correlation with plasma melatonin levels
Authors: Vacas MarÍa I. , Del Zar MarÍa de las M. , Martinuzzo Marta , Falcon Cristina , Carreras Luis O. , Cardinali Daniel P.
Published: February 2007

Abstract: Plasma melatonin concentrations and the effect of melatonin on arachidonic acid (AA)‐induced aggregation and thromboxane B2 (TxB2) production by platelet‐rich plasma (PRP) were examined in five normal male volunteers, sampled at 2 hr intervals from 21:30 to 09:30 hr. Peak plasma melatonin concentration was found at 03:30 hr. Inhibition by 10−6 M melatonin of AA‐induced PRP aggregation was observed only in samples taken at 01:30 hr. Assessment of the inhibitory effect of 10−9–10−6 M melatonin on AA‐induced TxB2 production indicated that melatonin activity was greater at 01:30 h as compared to late night. Assessed as a global effect, the inhibitory activity of melatonin on PRP TxB2 showed a maximum at 01:30 hr and minimal effects at 03:30 hr, at the time when plasma concentrations of melatonin were highest. These results indicate the existence of a nocturnal variation in sensitivity of human platelets to melatonin, with a peak that precedes the maximum in circulating melatonin levels.
Pineal serotonin is resistant to depletion by serotonergic neurotoxins in rats
Authors: Champney Thomas H. , Matthews Robert T.
Published: February 2007

Abstract: Administration of 3,4‐methylenedioxymethamphetamine (MDMA) or para‐chloroamphetamine (pCA) to adult rats is neurotoxic to serotonin (5HT) nerve terminals and cell bodies. MDMA (10 mg/kg) reduces; 5HT levels in the frontal cortex, medial basal hypothalamus, and striatum acutely and 17 days after a series of multiple injections. The acute reductions occur within 1–2 hr after injection of doses greater than 3 mg/kg. A single injection of pCA reduces 5HT levels in the above mentioned brain regions as well as in the brain stem. However, none of these treatments are able to alter 5HT levels in the pineal gland. It appears that the pineal does not contain the 5HT reuptake system that is thought to be necessary for the neurotoxicity of MDMA and pCA.
Immunohistological localization of melatonin in the pineal gland and retina of the rat
Authors: Mennenga Kirsten , Ueck Manfred , Reiter Russel J.
Published: February 2007

Abstract: An incubation procedure for the demonstration of melatonin is described using freeze‐dried, unfixed material embedded in vacuum directly in glycolmethacrylate. The results indicate the binding of melatonin in the nucleus of pineal parenchymal cells and in the outer nuclear layer of the retina of rats; binding is greater at night than during the day.
Participation of the pineal gland in sexual maturation of female rainbow trout (Oncorhynchus mykiss Walbaum)
Authors: Popek Wlodzimierz , Bieniarz Krzysztof , Epler Piotr
Published: February 2007

Abstract: In the study rainbow trout, pinealectomized at two different periods of their sexual cycle, i.e., at either 1 or 5 months before spawning, were studied. It was found that the lack of the pineal gland in the period directly preceding the spawning had no statistical effect on either spawning or the number of females that produced eggs.

Pinealectomy performed during vitellogenesis delayed spawning by about 2 weeks and resulted in the absence of ovulation in 20% of the females. The results suggest that the pineal gland may influence the hypothalamo‐pituitary‐gonadal axis by altering the maturation period and controlling spawning in the rainbow trout.
Melatonin concentrations in pineal organ culture are suppressed by sera from tumor‐bearing mice
Authors: Leone A. M. , Skene D.
Published: February 2007

Leone AM, Skene D. Melatonin concentrations in pineal organ culture are suppressed by sera from tumor‐bearing mice. J. Pineal Res. 1994: 17: 17–19.

The melatonin rhythm is significantly attenuated in a wide range of human and animal tumor types. Since surgical removal of the tumor has been shown to restore this rhythm, we hypothesized that a plasma borne tumor‐associated factor (TAMF) could be responsible. A population of mice were injected with tumor cells and sequentially killed and bled over the following 9 days, i. e., to the maximal state of tumor growth. Pooled serum from the different collection days was added to an established pineal organ culture system, and melatonin concentrations measured. A highly significant correlation between melatonin concentrations and the stage of tumor growth was seen with maximal inhibition occurring at day 9 (P < 0. 01). These findings support our hypothesis and may help to explain the mechanism whereby melatonin rhythmicity is suppressed in cancer patients.
Melatonin modulates growth factor activity in MCF‐7 human breast cancer cells
Authors: Cos Samuel , Blask David E.
Published: February 2007

Cos S, Blask DE. Melatonin modulates growth factor activity in MCF‐7 human breast cancer cells. J. Pineal Res. 1994: 17: 25–32.

Melatonin has been shown to have direct oncostatic actions on estrogen‐responsive, MCF‐7 human breast cancer cells in culture. In the present study, we examined whether these inhibitory actions on cell growth may be mediated through actions on bioassayable growth factor activity. In order to test this hypothesis, we estimated the growth factor activity of conditioned medium (CM) from estradiol (E2), or melatonin‐treated cells, in the presence or absence of melatonin on MCF‐7 cell growth. We also determined whether melatonin inhibits the action of epidermal growth factor (EGF) action in the absence of E2. The addition of melatonin (10‐9 M) to the cultures of MCF‐7 cells with CM from E2 (10‐8 M)‐treated cells significantly inhibited the growth stimulatory activity of CM, suggesting that melatonin inhibited cell proliferation by blocking the action of E2‐induced autocrine growth stimulatory factors. Conditioned medium from melatonin‐treated cells significantly inhibited cell proliferation, while an additional supply of melatonin to these cultures had an even greater inhibitory effect. Melatonin was also active in the complete absence of serum as long as cell growth was stimulated by EGF, an E2‐inducible growth factor. The inhibitory effect of melatonin increased as the dose of EGF increased. This non‐antiestrogenic inhibitory effect of melatonin was reversed by E2, but not by EGF itself, suggesting that melatonin requires accessible estrogen receptor sites for its inhibitory activity on the growth stimulating action of EGF. Taken together, these findings suggest that melatonin may inhibit the action and/or release of growth stimulatory factors as well as stimulate the release of growth inhibitory factors in culture. Furthermore, these findings indicate an important interaction of melatonin with E2‐inducible autocrine growth factors such as EGF in the inhibition of MCF‐7 cell growth.
Effects of season, temperature, and photoperiod on plasma melatonin rhythms in the goldfish, Carassius auratus
Authors: Iigo Masayuki , Aida Katsumi
Published: February 2007

Abstract: Effects of season, environmental temperature, and photoperiod on plasma melatonin concentrations were studied in the goldfish, Carassius auratus. When goldfish were reared under natural conditions, melatonin levels at mid‐dark exhibited seasonal changes, with higher levels obtained in June and September than in December and March. When fish were kept under light: dark (LD) cycle of 12: 12 at 5, 15, or 25°C during March‐April, temperature‐dependent increases in melatonin levels at mid‐dark were observed. When animals were maintained under LD 16: 8 or LD 8: 16 in combination with temperature changes (5, 15, and 25°C) during January‐February, the duration of nocturnal elevation in melatonin was controlled by the length of the scotophase while the amplitude was influenced by environmental temperature. These results indicate that plasma melatonin profiles in the goldfish exhibit seasonal changes that are regulated by both photoperiod and temperature.
Influences of season and of temperature, photoperiod, and subcutaneous melatonin infusion on the glomerular filtration rate of ewes
Authors: Tsuda Tsuneyuki , Ide Masashi , Iigo Masayuki
Published: February 2007

Abstract: Influences of season and of temperature, photoperiod, and subcutaneous melatonin infusion on glomerular filtration rate (GFR) were measured in ewes. There was a seasonal difference of GFR between summer (June‐August) and winter (December‐February) in Tokyo (35°, 35°N); GFR was significantly (P < 0.05) higher in summer (4.2 ± 0.3 ml/ min/kg) than in winter (3.0 ± 0.2 ml/min/kg). GFR was measured after exposure to three types of photoperiod, 24L: 0D, 12L: 12D, and 0L: 24D, for 7 to 8 days. The value for GFR obtained at 20°C was significantly lower (P < 0.05) with 0L: 24D than with the other two photoperiodic conditions. GFR obtained during subcutaneous melatonin infusion (20μg/hr for 16 hr/ day for 7 days) with 24L: 0D conditions was significantly (P < 0.05) lower (2.5 ± 0.1 ml/min/kg) than without infusion (3.8 ± 0.3 ml/ min/kg) and was about the same as that obtained in animals under 0L: 24D conditions. At 30°C, GFR exhibited no difference between the 3 photoperiodic conditions and was always lower than that found at 20°C. Possible influences of melatonin on GFR are discussed.
Exploratory laser flash photolysis study of free radical reactions and magnetic field effects in melatonin chemistry
Authors: Scaiano J. C.
Published: February 2007

Abstract: Melatonin is an excellent free radical scavenger, reacting with ferf‐butoxyl and cumyloxyl radicals with rate constants of 3.4 × 107 and 6.7 × 107 M−1s−1, respectively. Reaction with benzophenone triplet occurs with a near‐diffusion‐controlled rate constant of 7.6 × 109 M−1s−1 in acetonitrile and probably involves charge transfer. When the radical pair formed by reaction of benzophenone triplet and melatonin is sequestered in a micelle, it is subject to extensive magnetic field effects that can be readily interpreted by the radical pair model.
Does melatonin affect calcium influx in human aortic smooth muscle cells and estradiol‐mediated calcium antagonism?
Authors: Mück A.O. , Seeger H. , Bartsch C. , Lippert T.H.
Published: February 2007

Abstract: The pineal hormone melatonin showed no effect on voltage‐gated calcium channels in cultured human aortic smooth muscle cells. In combination with estradiol, which blocked calcium channels, melatonin did not antagonize the effect of estradiol. It is concluded that melatonin seems to have different effects on voltage‐gated calcium channels of divergent cell types since the positive action of melatonin previously observed on rat cardiac membranes by other authors could not be seen in the present investigations with human vascular smooth muscle cells.
Hydroxyindole‐O‐methyltransferase mRNA expression in a subpopulation of photoreceptors in the chicken retina
Authors: Wiechmann Allan F.
Published: February 2007

Abstract: Hydroxyindole O‐methyltransferase (HIOMT, EC 2.1.1.4) catalyzes the final step in the synthesis of melatonin in the pineal gland and retina. HIOMT mRNA was localized by in situ hybridization in the chicken retina to some, but clearly not all, photoreceptors, while in the pineal gland, most pinealocytes displayed a positive hybridization signal. The in situ hybridization localization was confirmed by immunocytochemistry, using an antibody directed against a synthetic chicken HIOMT peptide. Western blot analysis demonstrated an immunoreactive protein of about 40 kilodaltons in the pineal, but the HIOMT protein was below detectable levels in the retina. However, the HIOMT‐peptide antibody did identify a modestly immunoreactive subpopulation of retinal photoreceptors. These observations suggest that, in the chicken, melatonin biosynthetic activity is located mainly in a subpopulation of retinal photoreceptors and in most pinealocytes.
In vitro and in vivo protection against kainate‐induced excitotoxicity by melatonin
Authors: Giusti Pietro , Franceschini Davide , Petrone Marcella , Manev Hari , Floreani Maura
Published: February 2007

Abstract: In this study, the protective effect of melatonin against kainate (KA)‐induced neurotoxicity was evaluated in vitro and in vivo. In rat brain synaptosomes, KA‐induced oxidative stress was measured as shown by significant increases in both the basal generation of reactive oxygen species (ROS), assessed by a fluorescent method, and lipid peroxidation, evaluated as malondialdehyde (MDA) levels. Melatonin decreased, in a concentration‐dependent manner, KA‐induced lipid peroxidation. The intrinsic fluorescence of melatonin molecule hindered the evaluation of its protective effect against KA‐induced ROS generation. However, melatonin was able to reduce FeSO4/ascorbate‐induced ROS generation. The melatonin protective effect was confirmed by in vivo experiments: 73% of rats injected with KA (10 mg/kg i.p.) died within 5 days; melatonin administration i.p. significantly reduced mortality of the animals. The present results suggest that melatonin might be considered a pharmacological agent for the treatment of neurodegenerative pathologies.
Modulation of ganglion cell activity in the pineal gland of the rainbow trout: Effects of cholinergic, catecholaminergic, and GAB Aergic receptor agonists
Authors: Brandstatter Roland , Hermann Anton
Published: February 2007

Abstract: Second order neurons within intact isolated pineal glands of the rainbow trout were explored by extracellular recordings to investigate modulatory effects of putative intrapineal neurotransmitters. Acetylcholine, dopamine, and norepinephrine were found to increase ganglion cell activity in a majority of cells tested. The excitatory effects of acetylcholine, dopamine, and norepinephrine were mimicked by muscarinic, dopamine D2, and β‐adrenergic receptor agonists and significantly increased with the applied light intensity, resulting in an attenuation of the ganglion cell response to light. GABA decreased discharge activity in most cells tested. This effect, which could be mimicked with the GABAA receptor agonist piperidine, was independent from the adaptive status. Acetylcholine and GABA were still active if applied during synaptic blockade with low Ca++ high Mg++‐perfusion medium, whereas dopamine and norepinephrine exhibited no effects if applied during synaptic blockade, suggesting a differential cellular distribution of neurotransmitter receptors in the trout pineal gland. These data demonstrate that ganglion cell activity in the trout pineal gland is under the influence of several neurotransmitters, including acetylcholine, dopamine, norepinephrine, and GABA, which is in contrast to the originally proposed simple bineuronal transduction pathway from photoreceptors onto ganglion cells. Since the above‐mentioned neurotransmitters are believed to be released from pineal interneurons, we may conclude that ganglion cell activity in the teleost pineal gland is, similarly to the retina, the product of photoreceptor signals and a modulatory active interneuronal system.
Clarifying plasma melatonin profiles in domestic pigs: A critical and comparative evaluation of two radioimmunoassay systems
Authors: Klupiec Corinna , Evans Gareth , Love Robert J. , Kennaway David J.
Published: February 2007

Klupiec C, Evans G, Love RJ, Kennaway DJ. Clarifying plasma melatonin profiles in domestic pigs: A critical and comparative evaluation of two radioimmunoassay systems. J. Pineal Res. 1997; 22:65–74. © Munksgaard, Copenhagen.

The results of a direct radioimmunoassay (RIA) for porcine plasma melatonin, suggesting a relationship among plasma melatonin, feed intake and photoperiod, were investigated by comparison with the results of an extracted RIA. These findings were further examined by analysis of a small number of samples using gas chromatography‐mass spectrometry (GCMS). The results identified inadequacies in the specificity of the direct RIA and failed to provide evidence for an effect of feed intake on melatonin secretion. Instead, it appeared that feed restriction exacerbated nonspecificity in the direct RIA. The cause of nonspecificity, and its effect on analysis of daily plasma melatonin profiles, were examined. The plasma component(s) responsible for nonspecificity was (were) not identified. However, the results suggest that characteristics of the antiserum used in the direct RIA are involved in the mechanism by which nonspecificity is induced. Results obtained using the extracted assay revealed that plasma melatonin concentrations in prepubertal gilts and pregnant sows exhibit a diurnal pattern, in which concentrations are low during daylight and modestly increased during darkness. Using the direct RIA, the same profiles exhibited highly variable melatonin concentrations showing little association with the light‐dark cycle. Thus, assay specificity was identified as a factor contributing to inconsistencies in the literature describing plasma melatonin in the domestic pig and the importance of rigorous validation of RIAs was demonstrated. Furthermore, the results indicate that plasma melatonin concentrations in domestic pigs, as in other mammalian species, are entrained by the light‐dark cycle.
Phototransduction cascade and circadian oscillator in chicken pineal gland
Authors: Okano Toshiyuki , Fukada Yoshitaka
Published: February 2007

ABSTRACT: The chicken pineal gland has an endogenous circadian oscillator that controls the diurnal oscillation of N‐acetyltransferase activity responsible for melatonin rhythm. It has been speculated that the chicken pineal cell contains a photoreceptive molecule that receives the environmental light signal and transmits the signal to the oscillator for resetting the phase. In spite of several lines of evidence suggesting the similarity between retinal and pineal photon‐signal transducing proteins, the identity of the photoreceptive molecule had been an open question. In 1994, we isolated a pineal cDNA encoding a novel photoreceptive molecule and named it “pinopsin.” The protein expressed in 293EBNA cells bound 11‐cis‐retinal to form a blue‐sensitive pigment with an absorption maximum at about 470 nm. A putative G‐protein interaction site of pinopsin shared a relatively high similarity in amino acid sequence to that of rhodopsin, implying that pinopsin functionally couples with transducin or transducin‐like G‐protein(s) in the pineal cells. We have cloned a cDNA for chicken pineal transducin α‐subunit, and the deduced amino acid sequence contained a potential site to be ADP‐ribosylated by pertussis toxin (PTX). Therefore, the transducin‐mediated pathway could be blocked by PTX, though previous studies showed that treatment of the cultured chicken pineal cells with PTX had no effect on the light‐induced phase‐shift of the oscillator. Accordingly, it is unlikely that transducin mediates the light‐input pathway to the oscillator, which may involve PTX‐insensitive G‐protein(s) or some unidentified component(s). The G‐protein coupled receptor‐mediated signaling processes regulating melatonin synthesis are discussed.
Absence of chronic effect of exposure to short‐wave radio broadcast signal on salivary melatonin concentrations in dairy cattle
Authors: Stärk Katharina D.C. , Krebs Thomas , Altpeter Ekkehardt , Manz Bernhard , Griot Christian , Abelin Theodor
Published: February 2007

ABSTRACT: A pilot study was conducted to investigate the influence of electromagnetic fields in the short‐wave range (3–30 MHz) radio transmitter signals on salivary melatonin concentration in dairy cattle. The hypothesis to be tested was whether EMF exposure would lower salivary melatonin concentrations, and whether removal of the EMF source would be followed by higher concentration levels. For this pilot study, a controlled intervention trial was designed. Two commercial dairy herds at two farms were compared, one located at a distance of 500 m (exposed), the other at a distance of 4,000 m (unexposed) from the transmitter. At each farm, five cows were monitored with respect to their salivary melatonin concentrations over a period of ten consecutive days. Saliva samples were collected at two‐hour intervals during the dark phase of the night. As an additional intervention, the short‐wave transmitter was switched off during three of the ten days (off phase). The samples were analyzed using a radioimmunoassay. The average nightly field strength readings were 21‐fold greater on the exposed farm (1.59 mA/m) than on the control farm (0.076 mA/m). The mean values of the two initial nights did not show a statistically significant difference between exposed and unexposed cows. Therefore, a chronic melatonin reduction effect seemed unlikely. However, on the first night of re‐exposure after the transmitter had been off for three days, the difference in salivary melatonin concentration between the two farms (3.89 pg/ml, CI: 2.04, 7.41) was statistically significant, indicating a two‐ to seven‐fold increase of melatonin concentration. Thus, a delayed acute effect of EMF on melatonin concentration cannot completely be excluded. However, results should be interpreted with caution and further trials are required in order to confirm the results.
A note on the time dependence of pineal gland research publications
Authors: Graham Daniel J. , McNulty John A.
Published: February 2007

Graham DJ, McNulty JA. A note on the time dependence of pineal gland research publications. J. Pineal Res. 1997; 23:59–62. ©Munksgaard, Copenhagen

Counts of the number of publication titles containing the search truncation “pinea*” were compiled via Current Contentsover the time period 1978–1994. These counts and their time dependence were examined for autocorrelations and frequency spectral components. Such analyses were carried out irrespective of either author, research laboratory, funding, or other factors. Interestingly, the results show the research publication rate in pineal studies to be linked to community history. In particular, the interactions affecting output among community members operate on a few characteristic time scales ranging from one to several years.
Melatonin prevents β‐amyloid‐induced lipid peroxidation
Authors: Daniels W.M.U. , van Rensburg S.J. , van Zyl J.M. , Taljaard J.J.F.
Published: February 2007

Daniels WMU, van Rensburg SJ, van Zyl JM, Taljaard JJF. Melatonin prevents β‐amyloid‐induced lipid peroxidation. J. Pineal Res. 1998; 24:78–82. © Munksgaard, Copenhagen

β‐Amyloid is a major constituent of senile plaques that occur in the brains of Alzheimer's disease (AD) patients. Cell culture studies have shown that high concentrations of β‐amyloid are toxic and damage biological macromolecules. A number of experiments have shown that melatonin is a potent antioxidant. Melatonin not only neutralizes oxygen‐derived free radicals but can also scavenge species of other types such as carbon‐centered free radicals. The present study was designed to determine whether P‐amyloid toxicity would cause lipid peroxidation of human platelet membranes. Since aluminum has been implicated in the etiology of AD, we investigated the effects of aluminum on lipid peroxidation and whether the harmful effects of β‐amyloid are aggravated by aluminum. We also investigated whether melatonin had the ability to protect against (3‐amyloid toxicity. Our results indicate that both β‐amyloid and aluminum dose‐dependently increased lipid peroxidation in platelet membranes. Aluminum was more potent than β‐amyloid. Incubation of platelet membranes with increasing concentrations of aluminum in the presence of 100 μM β‐amyloid (fragment 25–35) resulted in lipid peroxidation levels of similar magnitude as the two substances, respectively. Prior administration of melatonin dose‐dependently inhibited this effect. These results confirm the toxic effects of β‐amyloid to biological membranes. While aluminum itself damages membranes, its presence did not exacerbate the toxic effects of β‐amyloid. Melatonin effectively reduced the lipid peroxidation induced by β‐amyloid and aluminum, suggesting that its supplementation to AD patients may be beneficial.
Melatonin prevents apoptosis induced by 6‐hydroxydopamine in neuronal cells: Implications for Parkinson's disease
Authors: Mayo Juan Carlos , Sainz Rosa Maria , Uria Higinio , Antolin Isaac , Esteban Manuel M. , Rodriguez Carmen
Published: February 2007

Abstract: It was recently reported that low doses of 6‐hydroxydopamine (6‐OHDA) induce apoptosis of naive (undifferentiated) and neuronal (differentiated) PC 12 cells, and this system has been proposed as an adequate experimental model for the study of Parkinson's disease. The mechanism by which this neurotoxin damages cells is via the production of free radicals. Given that the neurohormone melatonin has been reported 1) to be a highly effective endogenous free radical scavenger, 2) to increase the mRNA levels and the activity of several antioxidant enzymes, and 3) to inhibit apoptosis in other tissues, we have studied the ability of melatonin to prevent the programmed cell death induced by 6‐OHDA in PC12 cells. We found that melatonin prevents the apoptosis caused by 6‐OHDA in naive and neuronal PC12 cells as estimated by 1) cell viability assays, 2) counting of the number of apoptotic cells, and 3) analysis and quantification of DNA fragmentation. Exploration of the mechanisms used by melatonin to reduce programmed cell death revealed that this chemical mediator prevents the 6‐OHDA induced reduction of mRNAs for several antioxidant enzymes. The possibility that melatonin utilized additional mechanisms to prevent apoptosis of these cells is also discussed. Since this endogenous agent has no known side effects and readily crosses the blood‐brain‐barrier, we consider melatonin to have a high clinical potential in the treatment of Parkinson's disease and possibly other neurodegenerative diseases, although more research on the mechanisms is yet to be done.
Time‐dependent effects of melatonin on immune measurements in male Syrian hamsters
Authors: Champney Thomas H. , Allen Gregg C. , Zannelli Michael , Beausang Lee Anne
Published: February 2007

Abstract: Adult, male Syrian hamsters received daily subcutaneous melatonin (25 μg) injections or vehicle injections at 08:00 or 17:00 hr for 11 weeks. Body weights were measured weekly throughout the experiment and testes weights, spleen weights, and serum was collected at the end of the experiment. The spleens were sectioned and immunocytochemically analyzed for immunoglobulin G and serum levels of interferon‐gamma, interleukin‐2, and interleukin‐4 were determined in heterologous mouse assays. Melatonin injections at 17:00 hr, but not at 08.00 hr, increased body weights, decreased testes weights and serum testosterone levels, and had no effect on immunoglobulin G content in the spleen. Likewise, melatonin injections at 17:00 hr, but not at 08:00 hr, increased serum interferon‐gamma levels, had no effect on interleukin‐2 levels, and appeared to increase interleukin‐4 levels. Since melatonin injections at 08:00 hr were ineffective in altering immune measurements and correlations between reproductive measures and immune measures were high, the most parsimonious explanation for these results is that melatonin injections at 17:00 hr depressed reproductive hormone levels and these depressed levels altered immune measures.
The effect of melatonin on cellular activation processes in human blood
Authors: Fjærli O. , Lund T. , Østerud B.
Published: February 2007

Abstract: The pineal hormone melatonin, due to its lipophilic nature, has access to every cell and every part of a cell in the body, suggesting that it could exert effects on blood immune cells. The regulation of the activation of monocytes may be important in a number of diseases, especially pathophysiological conditions associated with inflammatory reactions. Considering this, a study on the effect of melatonin on monocytes in whole blood was carried out. Melatonin added at a final concentration of 5 ng/mL to whole blood in vitro reduced lipopolysaccharide (LPS)‐induced tissue factor (TF) activity in monocytes by 55% in blood from a group of subjects with melatonin‐sensitive cells. At even lower concentrations of melatonin (20‐50 pg/mL) and in the physiological range, a trend of suppressed LPS‐induced TF activity by ∼ 20% was seen. A further indication of a downregulation of LPS‐stimulated monocytes by melatonin was shown by its reduction of LPS‐induced tumor necrosis factor (TNF). Twenty to one hundred pg/mL melatonin caused a significant reduction of LPS‐induced TNF production by ∼ 25–30%. In contrast, melatonin at a final concentration of 10 pg/mL, added to whole blood incubated with LPS and also the phorbol ester, PMA, caused a signficant rise of 25%; whereas 100 pg/mL enhanced LPS + PMA‐induced TNF by ∼ 80% as compared to LPS + PMA alone. These effects were not detectable during the winter darkness of Tromsø (70°N), probably due to the high content of melatonin in the blood even at daytime. These results show that melatonin may have a beneficial effect by suppressing the expression of TF activity in LPS‐stimulated monocytes. Furthermore, the results indicate that LPS‐induced TF in monocytes of whole blood is independent of protein kinase C (PKC) activation. Melatonin is probably amplifying cellular activation reactions that are PKC‐dependent. This may be physiologically important in upregulation of the immune system.
Melatonin as an antioxidant in retinal photoreceptors
Authors: Marchiafava Pier Lorenzo , Longoni Biancamaria
Published: February 2007

Abstract: Dark‐adapted, single photoreceptors isolated from the frog retina produce reactive oxygen species (ROS) after about 1 min of illumination with saturating light that we verified by their oxidation of preloaded dihydrorhodamine 123 (DHR) into the fluorescent rhodamine 123 (RHO). In this preparation we tested the antioxidant effects of vitamin E and of melatonin. Melatonin at picomolar and low nanomolar concentrations was determined to be 100 times more potent in inhibiting the light‐induced oxidative processes than was vitamin E. On the contrary, both compounds exerted potent prooxidant effects at micromolar concentrations that is above the physiological levels of melatonin. This provides evidence that physiological concentrations of melatonin in a living cell may exert protective actions against a natural oxidant stimulus (light). This helps to define the functional role of endogenous melatonin in photoreceptors, which by their physiological characteristics, are among the marked producers of ROS in the organism.
Daily and light‐at‐night induced variations of circulating 5‐methoxytryptophol (5‐ML) in ewes with respectively high and low nocturnal melatonin secretion.
Authors: Vivien‐Roels B. , Pévet P. , Zarazaga L. , Malpaux B. , Chemineau P.
Published: February 2007

Abstract: The aim of the present study was to determine whether the genetic differences previously reported in ewe plasma melatonin concentrations were correlated with differences in the synthesis and release of other 5‐methoxyindoles. To determine if 5‐methoxytryptophol (5‐ML), which is known to be present in large amounts in the sheep pineal gland, is released, as is melatonin, into the general circulation, and if some temporal relationships between 5‐ML and melatonin release could be observed, two groups of ewes were selected with respect to their endogenous melatonin secretion: in the first experiment, ten ewes from the low melatonin group (low group) and ten ewes from the high melatonin group (high group). 5‐ML was measured every hour during a 24‐hr period by radioimmunoassay. In all ewes, 5‐ML was released during day‐time, the rhythm of 5‐ML concentrations being inversely related with the melatonin rhythm. Both day‐time and night‐time 5‐ML concentrations were higher in the ewes from the high group than in the ewes from the low group (14.7 ± 1.0 pg/mL plasma versus 6.4 ± 0.3 pg/mL plasma during the day, 3.1 ± 0.2 pg/mL plasma versus 1.9 ± 0.2 pg/mL plasma during the night). The 5‐ML/melatonin ratio appeared much higher during the day than during the night but was very similar in both groups (day‐time: 1.03 in the high group versus 1.16 in the low group, night‐time: 0.01 in both groups). In a second experiment, six low group and seven high group ewes were submitted to 1 hr of extra light at night. 5‐ML increased and melatonin decreased during extra light. Our results clearly show for the first time a daily variation in circulating 5‐ML. and that the strong genetic contribution in the variability in melatonin concentrations in sheep are clearly correlated with a similar variability in 5‐ML concentrations. Whether 5‐ML, like melatonin, plays a physiological role in the different adaptation processes to the environment remains to be determined.
Properties of pressure‐sensitive adhesive tapes with soft adhesives to human skin and their mechanism
Authors: Tokumura Fumio , Homma Takeyasu , Tomiya Toshiki , Kobayashi Yuko , Matsuda Tetsuaki
Published: February 2007

Background/purpose: The use of soft adhesives in the manufacture of pressure‐sensitive adhesive tapes has recently increased. The dermal peeling force of adhesive tapes with soft adhesives was studied.

Methods: Four kinds of adhesive tapes with adhesives of different softness were made, by adding varying amounts of isopropyl myristate as a softener. The tapes were applied on the flexor side of the forearm of six healthy male volunteers. The dermal peeling force, the amount of stripped corneocytes, the level of pain when the tapes were removed and the degree of penetration of adhesives into the sulcus cutis (skin furrows) were evaluated at 1 and 24 h after application of the tapes. Furthermore, a skin model panel (a sulcus cutis and crista cutis model panel) and a crista cutis model panel were constructed from a general stainless‐steel panel, and the peeling force of the tapes against the model panels was measured.

Results and conclusion: As the softness of adhesives increased, the peeling force against a general stainless‐steel panel with a flat surface decreased, although the peeling force against human skin did not significantly change. The amount of stripped corneocytes on the removed tapes and the level of pain when the tapes were removed decreased with the increase in softness of the adhesives. These results suggest that adhesive tapes with soft adhesives that contain isopropyl myristate as a softener are suitable for the skin. Furthermore, the degree of penetration of adhesive into the sulcus cutis increased as the softness of adhesives increased. Upon evaluation of the peeling force against the model panels, as the softness of adhesives increased, there was a slight decrease in the peeling force against the skin model panel, while there was a remarkable decrease in the peeling force against the crista cutis model panel. These results suggest that the lack of change in the dermal peeling force as the softness of adhesives increased was caused by penetration of soft adhesive into the sulcus cutis, and that the decrease in the amount of stripped corneocytes was caused by a decrease in the peeling force against the crista cutis, which consists of corneocytes mainly removed by the tapes.
Evaluation of Ceramic Matrix Composites by Thermal Diffusivity Imaging
Authors: Sun Jiangang
Published: February 2007

Because of the complex structural design and multiple processing steps, ceramic matrix composites (CMCs) typically contain a variety of flaws distributed throughout the volume. These flaws need to be detected and characterized because they are detrimental to CMC material properties. Thermal diffusivity imaging is a nondestructive evaluation method that can quantitatively determine the thermal property of a CMC component. Thermal diffusivity is an intrinsic material property that not only depends on the material constituents but also on the micro‐ and macrostructure of the CMC component. This paper investigates fundamental theories for thermal diffusivity measurement using pulsed thermal imaging from two‐ and one‐sided setups. The variation of thermal diffusivity is examined for two types of flaws, voids and cracks, that are commonly present within CMCs. The sensitivity of thermal imaging to detect small and large flaws is analyzed and evaluated with measured thermal diffusivity data. In addition, analysis of fracture theories for the mechanical and thermal properties of materials with distributed microcracks has identified that thermal diffusivity may be used to determine the degradation of mechanical properties and, therefore, to predict the remaining life of a CMC component. Preliminary results for correlating thermal and mechanical properties are discussed.
Bipolar ejection by the symbiotic binary system Z And during its 2006 outburst
Authors: Tomov N. A. , Tomova M. T. , Bisikalo D. V.
Published: February 2007

High-resolution data in the region of the Hα line have been obtained at the time of light maximum and after it for the 2006 optical outburst of the symbiotic binary Z And. A blueshifted absorption component indicating an outflow velocity of about 1400 km s−1, as well as additional emission components with similar velocities, situated on the two sides of the main peak of the line, were observed during that time. It is suggested that all of them are spectral signatures of bipolar outflow, observed for the first time in the optical spectrum of this binary. The emission measure and the mass of the nebular part of the streams have been estimated approximately, reaching values of up to about 6 × 1057 cm−3 and 8 × 10−8 M⊙.
MEASUREMENT OF THERMAL CONDUCTIVITY OF DAIRY PRODUCTS AND MARGARINES
Authors: SWEAT VINCENT E. , PARMELEE CARLTON E.
Published: February 2007

A line heat source thermal conductivity probe was used to measure the thermal conductivity of 28 dairy products and margarines at 0, 20, and 40†C. Water and fat contents and mass density of each sample were also measured and correlated to thermal conductivity.

There was a strong positive correlation between thermal conductivity and water content, and an inverse correlation between thermal conductivity and fat content. Temperature did not appear to be a significant factor over the limited temperature range studied. Although there was some correlation between mass density and non‐fat solids fraction, no correlation was observed between mass density and thermal conductivity.
RHEOLOGICAL BEHAVIOR OF ULTRA‐HIGH TEMPERATURE STEAM INJECTED DAIRY PRODUCTS ON AGING1
Authors: SWARTZEL K.R. , HAMANN D.D. , HANSEN A.P.
Published: February 2007

Milk (0.5, 3.25, and 10.5% fat) was processed in an ultra‐hightemperature steam injection system. Process time‐temperature relationships included 138, 143, and 149°C for 20.3s; 143 and 149°C for 6.9 s; and 149°C for 3.4 s. Product from each run was stored at 4, 24, and 40°C Using four commercial viscometer assemblies the flow behavior constants of the power‐law equation were determined for each treatment through 60 weeks of storage. Regression analysis of the calculated power law constants resulted in a graphical summary of the history of flow properties for each treatment.

Age‐thickening (gelation) was found to be associated with process residence time, storage temperature, storage time, and fat level. Process temperature was not a significant factor. The shorter the residence time the faster gelation occurred. The earlier a sample gelled the faster its rate of gelation. For a given residence time, gelation developed first in samples of low percent fat and progressed through higher fat contents.

A gelation prediction nomograph based on fat level, residence time, and storage time is presented for a 24°C storage temperature.
RHEOLOGICAL MODELING OF UHT MILK GELS USING A CONE AND PLATE CREEP‐RELAXATION TEST1
Authors: SWARTZEL K.R. , HAMANN D.D. , HANSEN A.P.
Published: February 2007

The gelation of UHT steam injected dairy products was investigated by determining rheological model constants. Fat percentages of the products were 0.5, 3.25 and 10.5. Each product was processed at 143 °C for 6.9 s and stored at 24 °C. At four week intervals, from 55 to 85 weeks storage, cone and plate creep‐relaxation data was collected Three element rheological models were developed for each test date. Empirical relationships were derived relating the elastic and viscous constants to storage time for each fat content. The strongest parameter for all samples was the series elastic constant. The viscous constant was next with the Kelvin elastic constant being much weaker. All constants for all samples increased over storage time as gelling progressed (apparent viscosity increased). The lower the percent fat, the sooner gelling started and the faster the rate. The gelation of UHT milk was examined and found to depend heavily on the percent fat.