bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differential regulation of melatonin receptors by short‐ versus long‐term pinealectomy in the rat suprachiasmatic nuclei and pars tuberalis
Authors: Gauer François , Masson‐Pévet Murielle , Pévet Paul 
Published: February 2007

Gauer F, Masson‐Pévet M, Pévet P. Differential regulation of melatonin receptors by short‐ versus long‐term pinealectomy in the rat suprachiasmatic nuclei and pars tuberalis. J. Pineal Res. 1994: 16: 73–76.AbstractWe have investigated the effects of short‐ and long‐term pinealectomy on the density of melatonin receptors in both the suprachiasmatic nuclei (SCN) and pars tubercles (PT) of the rat. Short‐term pinealectomy (conducted 3‐5 days before sacrifice) induced a significant increase in the density of melatonin receptors in both structures. This increase can be interpreted as an up‐regulation of melatonin receptors following the absence of plasma melanoma. In contrast, 7 days after pinelectomy, the receptor density began to decrease, reaching a low point 1. 5 months after pinealectomy. At this time, the decrease represents a 40‐45% reduction in binding sites as compared with values measured 3–5 days after pinealectomy. This slow decrease could be related to a slowdown of melatonin receptor synthesis. These results suggest that emblazoning has a stimulatory effect on its own receptor synthesis. However, at 1. 5 months after pinealectomy a novel equilibrium between synthesis and hydrolysis seems to be reached. Melanoma does not appear to be indispensable for the synthesis of its receptors.
Localization and characterization of [125I]iodomelatonin binding sites in duck gonads
Authors: Ayre Elizabeth A. , Wang Zheng Pin , Brown Gregory M. , Pang Shiu Fun 
Published: February 2007

Ayre EA, Wang ZP, Brown GM, Pang SF. Localization and characterization of [125I]iodomelatonin binding sites in duck gonads. J. Pineal Res. 1994: 17: 39–47.AbstractThe characterization and localization of [125I]iodomelatonin binding sites in the gonads advances the understanding of possible regulatory sites of melatonin action. With the availability of [125I]iodomelatonin as a biologically active radioligand, our study utilized a combined approach of autoradiography for anatomical resolution together with an established radioligand binding assay to assess mid‐light [125I]iodomelatonin binding in the testes and ovaries of ducks. In the autoradiography study, specific [125I]iodomelatonin binding was shown to be homogeneous throughout the testes, while in the ovaries, specific [125I]iodomelatonin binding appeared to be concentrated around the follicle. Radioligand binding assay results indicated a single class of binding sites with the maximum number of [125I]iodomelatonin binding sites measured at 1. 91 ± 0. 70 fmol/mg protein in testicular membrane and 4. 54 ± 0. 64 fmol/mg protein in ovarian membrane. [125I]Iodomelatonin binding affinity, characterized by equilibrium dissociation constants of 29 ± 6 pmol/L in testicular membrane and 53 ± 9 pmol/L in ovarian membrane, was in accordance with circulating melatonin levels, suggesting an appropriate concentration for eliciting a physiological response. [I]Iodomelatonin binding in duck gonads satisfied all the criteria for a binding site, being rapid, stable, saturable, reversible, specific, and of high affinity, and may indicate a direct pineal‐gonadal connection.
Direct influence of melatonin on steroid, Nona peptide hormones, and cyclic nucleotide secretion by granulosa cells isolated from porcine ovaries
Authors: Sirotkin Alexander V. 
Published: February 2007

Sirotkin AV. Direct influence of melatonin on steroid, nonapeptide hormones, and cyclic nucleotide secretion by granulosa cells from porcine ovaries. J. Pineal Res. 1994; 17: 112–117.AbstractThe release of progesterone, estradiol‐173, oxytocin, arginine‐vasopressin, cAMP, and cGMP by cultured granulosa cells isolated from porcine ovaries without and in the presence of melatonin (0. 001, 0. 01, 0. 1, 1, 10, and 100 ng/ml medium) was analyzed. It was found that melatonin is able to inhibit progesterone and stimulate estuarial secretion. Melatonin treatments significantly inhibited oxytocin release. Some inhibition of vasopressin and cAMP and significant stimulation of cGMP also resulted from melatonin treatment. The present observations suggest a direct effect of melatonin on the steroid, nonapeptide hormone, and cyclic nucleotide release from porcine ovarian cells.
Effects of exposure to 16.7 Hz magnetic fields on urinary 6‐hydroxymelatonin sulfate excretion of Swiss railway workers
Authors: Pfluger Dominik H. , Minder Christoph E. 
Published: February 2007

Abstract: The aim of our study was to examine the effects of 16.7 Hz electromagnetic‐field exposure on pineal melatonin production in healthy humans. The study was based on comparing urinary 6‐hydroxymelatonin sulfate (6‐OHMS) levels of 108 male railway workers between leisure periods and days following the start of service on electrically powered engines (66 engineers) or working beneath transmission lines (42 railway employees such as train attendants and station managers; controls). A repeated measures design was used, i.e., each volunteer served as his own control. The exposure averaged 20 μTesla in the most exposed workers and around 1 μTesla in the least exposed. Apart from magnetic exposure the workers were subject to a shift work schedule with daily advances between 15 min and 1 hr. Melatonin was assessed by sampling urinary 6‐OHMS both in the morning and the early evening.Evening 6‐OHMS values appeared to be lowered by a factor of 0.81 (95%CI: 0.73–0.90) during work days compared to leisure days among engine drivers, but not in the controls. The lowering was not confined to certain types of shift work such as early, normal, or late shifts. During subsequent leisure periods evening values recovered significantly, mean ratio=1.27 (95%CI: 1.03–1.56), i.e., the effects appeared to be reversible. In contrast, morning 6‐OHMS samples of engineers and controls did not differ much between work and leisure days. There was, however, a tendency for a rebound of morning values in a leisure period following a work period both for engineers and controls. The observed pattern appears to be in line with predictions of the “phase response curve.” No evidence for a dose‐response relation was found. The results support the hypothesis that 16.7 Hz magnetic fields alter 6‐OHMS excretion in humans exposed to magnetic fields. An alternative explanation that cannot be excluded in this study is that the difference between engineers and controls is due to differential exposure to day light at work.
The amplitude of endogenous melatonin production is not affected by melatonin treatment in humans
Authors: Matsumoto Miki , Sack Robert L. , Blood Mary L. , Lewy Alfred J. 
Published: February 2007

Matsumoto M, Sack RL, Blood ML, Lewy AJ. The amplitude of endogenous melatonin production is not affected by melatonin treatment in humans. J. Pineal Res. 1997; 22:42–44. © Munksgaard, CopenhagenAbstractA physiological dose of melatonin (0.5 mg) or placebo was given at bedtime to night shift workers (n=21) for seven days, and endogenous melatonin profiles were measured on the eighth day. The amplitude of endogenous melatonin secretion was unchanged by treatment. Also, a melatonin treatment trial using a 50 mg daily bedtime dose for 37 days to a blind subject resulted in no change in the endogenous melatonin profile. We conclude that circulating melatonin can shift the phase, but does not alter the amplitude, of pineal melatonin secretion.
The role of the intracellular and extracellular serotonin in the regulation of melatonin production in rat pinealocytes
Authors: Miguez Jesús M. , Simonneaux Valérie , Pevet Paul 
Published: February 2007

Miguez JM, Simonneaux V, Pevet P. The role of the intracellular and extracellular serotonin in the regulation of melatonin production in rat pinealocytes. J. Pineal Res. 1997; 23:63–71. © Munksgaard, CopenhagenAbstractThis study investigated whether the activation of pinealocyte β‐adrenergic receptors is involved in the regulation of serotonin (5‐HT) synthesis and release, as it is for melatonin production. In addition, the role of the intra‐ and extra‐cellular 5‐HT in modulating the synthesis of melatonin induced by the β‐adrenergic agonist isoproterenol (ISO) was also studied. The incubation of dissociated pinealocytes with 0.1–10 IAM ISO resulted in a concentration‐dependent increase of melatonin synthesis. 5‐HT release and intracellular 5‐HT content were increased by 0.1 and 1 μM ISO but they were reduced after ISO 10 μM. Moreover, when incubated with the tryptophan hydroxylase inhibitor p‐chlorophenylalanine (PCPA), the secretion of 5‐HT as well as the intracellular 5‐HT levels were markedly reduced in both ISO‐stimulated and unstimulated conditions. Melatonin release was also inhibited by PCPA, although it responded in the expected manner to increasing concentrations of ISO. These data indicate that the release of 5‐HT from pinealocytes depends on the availability of cytoplasmic 5‐HT, which in turn is highly dependent on the tryptophan hydroxylase activity. In cells stimulated with moderate ISO concentrations, 5‐HT release may be an important regulatory process of pineal 5‐HT. After a large stimulation of N‐acetyltransferase (NAT) activity by ISO, the synthesis of melatonin prevails on 5‐HT release, whose decrease is associated to a deficit of intracellular 5‐HT. On the other hand, the present study shows that the incubation of pineal cells with high concentrations of 5‐HT or with a selective 5‐HT2 receptor agonist, α‐methyl‐5‐hydroxytryptamine, reverses partially the inhibitory effect of PCPA on the ISO‐stimulated melatonin synthesis. In contrast the 5‐HT2 antagonist, ketanserin, results in an inhibiton of the release of melatonin following ISO stimulation. These results suggest that released 5‐HT may have a role in the full expression of the β‐adrenergically induced NAT activity and, thus, may contribute to the optimal melatonin synthesis at night.
Intracellular melatonin distribution in cultured cell lines
Authors: Finocchiaro Liliana M. E. , Glikin Gerardo C. 
Published: February 2007

Finocchiaro LME, Glikin GC. Intracellular melatonin distribution in cultured cell lines. J. Pineal Res. 1998; 24:22–34. © Munksgaard, CopenhagenAbstractA specific antibody combined with a fluorescein‐labeled immunoglobulin was used to investigate the topographic distribution of melatonin in a variety of cells of different origins. Positive identification of both nuclear and cytosolic melatonin was confirmed in all the tested cells: Swiss 3T3 mouse fibroblasts, BCG1 bovine granulosa, NB41A3 mouse neuroblastoma, F9 mouse teratocarcinoma, MDCK normal canine kidney derived and human HeLa cell lines, as well as in human peripheral blood mononuclear leukocytes and rat splenic cells. In 3T3 mouse fibroblasts melatonin immunofluorescence partially colocalized with actin and serotonin immunostaining, but not with tubulin or actin stress fibers. Several distinct patterns of subcellular melatonin distribution, different from the bromodeoxyuridine‐labeled replication profiles, have been discerned throughout the cell cycle of synchronized 3T3 cells. In addition, synchronized 3T3 mouse fibroblasts cultured in the presence of 10‐‐3 M melatonin progressed more slowly through the cell cycle than control cells. These results suggest that melatonin may interact directly with nuclear and cytoskeletal structures probably affecting different cell functions such as cell cycle control, subcellular organization, and genome stability.
Melatonin supplementation does not prevent photostimulatory effects of night interruption lighting in Japanese quail
Authors: Meyer Wayne 
Published: February 2007

Meyer W. Melatonin supplementation does not prevent photostimulatory effects of night interruption lighting in Japanese quail. J. Pineal Res. 1998; 24:102–107. © Munksgaard, CopenhagenAbstractMale Japanese quail (Coturnix japonica) exposed to night interruption lighting were given melatonin either as single daily injections (10–100 mg/kg), or as continuous release implants. Birds were exposed to a base photoperiod of 8 hr of light, plus a 15 min night interruption pulse of light 14 hr after the beginning of the base photoperiod. Daily injections of melatonin were given 20 min prior to the night interruption pulse. Control birds either received no exogenous melatonin or received injections during the last 2 min of the night interruption pulse. Exogenous melatonin was able to induce sleep‐like behavior at higher doses but did not prevent gonadal recrudescence as measured by the cloacal protrusion area. The role of melatonin in avian reproduction appears to be different from that in mammals. Perhaps melatonin's role in birds is to regulate circadian activities, not circannual ones such as the onset of reproduction.
Molecular and cellular analyses of melatonin receptor‐mediated cAMP signaling in rat corpus epididymis
Authors: Li Li , Xu Jian N. , Wong Yung H. , Wong Joseph T.Y. , Pang Shiu F. , Shiu Stephen Y. W. 
Published: February 2007

Li L, Xu JN, Wong YH, Wong JTY, Pang SF, Shiu SYW. Molecular and cellular analyses of melatonin receptor‐mediated cAMP signaling in rat corpus epididymis. J. Pineal Res. 1998; 25:219–228. © Munksgaard, CopenhagenAbstractBy using 2‐[125I]iodomelatonin receptor binding studies, we have previously demonstrated high affinity melatonin receptors, the binding activities of which are regulated by testosterone, in the corpus epididymis of rats. In this report, some of the basic molecular and cellular characteristics of these high affinity melatonin receptors in rat corpus epididymis were analyzed. MEL1A and MEL1B receptor mRNAs were expressed by rat corpus epididymal epithelial cells as revealed by in situ hybridization. Functionally, these high affinity melatonin receptors are negatively coupled to adenylyl cyclase via pertussis toxin (PTX) sensitive Gi protein and the inhibitory effects of melatonin on forskolin‐stimulated cAMP accumulation were enhanced by 5α‐dihydrotestosterone (5α‐DHT). Interestingly, opposing interactions between melatonin and (β‐adrenergic receptor signaling in rat epididymal epithelial cells were observed with melatonin inhibiting norepinephrine‐ and isoproterenol‐stimulated cAMP accumulation. In conclusion, our data support a modulatory action of melatonin, mediated via pertussis toxin‐sensitive Gicoupled MEL1A and MEL1B receptors, in androgenic and adrenergic regulation of rat corpus epididymal epithelial cell functions.
Chronic exposure to 2.9 mT, 40 Hz magnetic field reduces melatonin concentrations in humans
Authors: Karasek Michal , Woldanska‐Okonska Marta , Czernicki Jan , Zylinska Krystyna , Swietoslawski Jacek 
Published: February 2007

Karasek M, Woldanska‐Okonska M, Czernicki J, Zylinska K, Swietoslawski J. Chronic exposure to 2.9 mT, 40 Hz magnetic field reduces melatonin concentrations in humans. J. Pineal Res. 1998; 25:240–244. © Munksgaard, CopenhagenAbstractDiurnal rhythm of serum melatonin concentrations was estimated in 12 men with low back pain syndrome before and after exposure to a very low‐frequency magnetic field (2.9 mT, 40 Hz, square wave, bipolar). Patients were exposed to the magnetic field for 3 weeks (20 min per day, 5 days per week) either in the morning (at 10: 00 hr) or in the late afternoon (at 18: 00 hr). Significant depression in nocturnal melatonin rise was observed regardless of the time of exposure. This phenomenon was characteristic for all the subjects, although the percent of inhibition of melatonin secretion varied among the studied individuals.
Transepidermal water loss after photodynamic therapy, UVB radiation and topical corticosteroid is independent of inflammation
Authors: Faurschou Annesofie , Wiegell Stine Regin , Wulf Hans Christian 
Published: February 2007

Background/purpose: Photodynamic therapy (PDT) and ultraviolet radiation cause an inflammatory reaction of the skin. This may lead to disruption of the skin barrier function. We examined the acute effect of PDT and short‐wave ultraviolet radiation (UVB) on the barrier function of the epidermis. Furthermore, we explored the effect on the skin barrier of topical corticosteroid previous to UVB exposure.Methods: Eight patients with acne vulgaris of the face were treated with PDT two times, and eight patients were left untreated. The transepidermal water loss (TEWL) was measured before treatment and at three control visits after PDT over 12 weeks. Twenty healthy volunteers were irradiated with UVB in two areas on the back. One area was treated with topical high‐potency corticosteroid before irradiation. TEWL was measured before, 15 min and 24 h after UVB exposure.Results: TEWL did not differ significantly between the various visits in each acne group and no significant difference in the TEWL between PDT‐treated patients and the control group was found at any visit (P>0.05). TEWL was not significantly altered 15 min and 24 h after a single exposure to UVB and no positive relationship was found between UV‐induced erythema and change in TEWL (P>0.05). Application of topical corticosteroid before UVB did not affect the skin barrier function significantly (P>0.05).Conclusion: Neither PDT nor a single exposure to UVB damaged the permeability barrier function of the skin and no effect on the TEWL was found when topical corticosteroid was applied previous to UVB irradiation.
First stars as a possible origin for the helium-rich population in ω Cen
Authors: Choi Ena , Yi Sukyoung K. 
Published: February 2007

Abstract
The most massive Galactic globular cluster ω Cen appears to have two, or perhaps more, distinct main sequences. Its bluest main sequence is at the centre of debate because it has been suggested to have an extremely high helium abundance of Y ∼ 0.4. The same helium abundance is claimed to explain the presence of extreme horizontal branch stars of ω Cen as well. This demands a relative helium-to-metal enrichment of ΔY/ΔZ ∼ 70; that is, more than one order of magnitude larger than the generally accepted value. Candidate solutions, namely asymptotic giant branch stars, massive stars and supernovae, have been suggested; but in this study, we show that none of them is a viable channel, in terms of reproducing the high value of ΔY/ΔZ for the constrained age difference between the red and blue populations. Essentially no populations with an ordinary initial mass function, including those candidates, can produce such a high ΔY/ΔZbecause they all produce metals as well as helium. As an alternative, we investigate the possibility of the stochastic ‘first star’ contamination to the gas from which the younger generation of ω Cen formed. This requires the assumption that the Population III star formation episode overlaps with that of Population II. While the required condition appears extreme, very massive objects in the first star generation provide a solution that is at least as plausible as any other suggestions made before.
HEAT AND MASS TRANSFER FUNDAMENTALS APPLIED TO FOOD ENGINEERING1
Authors: KING C. JUDSON 
Published: February 2007

ABSTRACTThere is a need for deeper qualitative and quantitative understanding of the heat and mass transfer mechanisms underlying various techniques for food production, processing, preservation and storage. This is important for the development of new food sources, for more economical and energy‐efficient processing of food from existing sources, for better food quality and quality control, and for adherence to new regulations such as nutritional labeling and shelf‐life dating.Several classes of food‐processing problems are presented where advances can be made on the basis of improved understanding of heat and mass transfer mechanisms. These include cases of competing transport, cases where transport competes with kinetics of chemical or biochemical reactions, and cases where determination and understanding of the rate‐determining factor are needed. Specific examples are drawn from drying processes, leaching and extraction, freezing, sterilization and enzyme deactivation, and artificial cultivation.
COMPACTION BEHAVIOR OF BULK WHOLE CORN KERNEL AT PRESSURES UP TO 34.6 MN/m2
Authors: MCNULTY P. B. , MOHSENIN N. N. 
Published: February 2007

ABSTRACTThe compaction behavior of whole corn kernel (1.8–22.0% mc, w. b.) was investigated by axial compression in an 18.5 mm diameter die using the Amatek Universal Testing Machine at 28°C. The maximum applied pressure in each experiment was 34.6 MN/m2 at loading rates of 0.028, 0.28, and 2.8 mm/s. Sample failure due to oil expression or sample extrusion did not occur in any test run. However, extensive physical rupture of corn kernels occurred at 1.8% moisture content and at lesser but significant levels at 6.6 and 9.7% moisture. At 15.9 and 22.0% moisture, samples were plastically deformed but little macroscopic kernel damage was evident. The effectiveness of compaction increased dramatically as moisture content increased up to 22.0% and then appeared to gradually decline with further increase in moisture. The average compression ratio at zero pressure varied from an average low of 1.70 at 1.8% to an average high of 1.92 at 22.0% mc corresponding to reductions in corn volume of 41 and 47%, respectively. In contrast, loading rate had little effect on density‐pressure profiles. The latter were not adequately characterized by powder compaction models reported in the literature. Substantial volumes of internal tissue gas were estimated with an average maximum of 21% in 15.9% moisture corn kernels.The extent of stress relaxation after termination of compaction increased as loading rate increased and was highest in 15.9% moisture corn. The pressures required for the ejection of compacted corn from the 18.5 mm die varied from 0.5 to 2.1 MN/m2 and revealed an average maximum value at 9.7% moisture. Ejection pressures were substantially independent of loading rate. The most stable compacted corn samples were those produced at the 15.9% moisture level although the compact stability in general was very poor indeed.
ANALYSIS AND ECONOMIC EVALUATION OF CONCENTRATION ALTERNATIVES FOR LIQUID FOODS — QUALITY ASPECTS AND COSTS OF CONCENTRATION
Authors: THIJSSEN H.A.C. , VAN OYEN N.S.M. 
Published: February 2007

ABSTRACTIn the selection of concentration processes the net added value of the concentrate with respect to the capital invested should be maximized. The net added value expressed per unit weight of feed is the difference between the gross added valve, being the increase in product value due to concentration, and the costs of concentration. The main factors affecting the gross added value and the concentration costs are treated systematically.The main factors influencing the gross added value are: thermal quality degradation by chemical reactions; loss of volatile aromas; and the concentration that is obtained in the process. The first two factors generally affect the gross added value negatively. The thermal effects of the various processes are shortly summarized. In revaporative concentration and reverse osmosis, aromas can usually be recovered by steam stripping and distillation if the aromas in the food are at least a factor of three more volatile than water. For liquids containing aromas with a relative volatility close to or smaller than unity only freeze concentration can be used, if the quality is to be fully retained.The approximate costs of concentration are given for dewatering capacities in the range of 1 to 50 tons per hour and 2000 to 7000 operational hr per year. As energy costs increase further, only concentration processes with a relatively low energy consumption will, at least for higher capacities, remain economically justified. The energy consumptions expressed in steam equivalents vary widely, viz. evaporation 0.16–1.3, freeze concentration 0.25–0.5, and membrane processes 0.01–0.48.