bluuebunny/crossref_metadata_2025_split huggingface dataset:
High melatonin solubility in aqueous medium
Authors: Shida CS. , Castrucci A. M. L. , Lamy‐Freund M. T. 
Published: February 2007

Shida CS, Castrucci AML, Lamy‐Freund MT. High melatonin solubility in aqueous medium. J Pineal Res. 1994:16:198–201.AbstractThe pineal hormone melatonin (5‐methoxy‐N‐acetyl‐tryptamine) has been reported to participate in important physiological processes. Although some of its biological actions seem to depend on a protein receptor at the membrane surface, melatonin is known to interact with a large variety of tissues and cells, suggesting that the molecule may not necessarily interact through a specific membrane receptor at a specific cell. Most discussions of melatonin activity have assumed that the molecule is highly hydrophobic. Contrary to belief, the present work shows that melatonin is soluble in a purely aqueous medium up to 5 ± 10‐3 M and describes a new method of melatonin preparation which shows the high hydrophilicity of the molecule. The results presented will affect the current biological hypothesis on the need of a melatonin carrier in the blood stream or the mechanisms which allow the hormone to cross the cell membrane and interact at the level of the nucleus.
Characterization or the chicken brain melatonin‐binding protein using iodinated and triturated ligands
Authors: Kennaway David J. , Hugel Helmut M. , Rowe Shawn A. 
Published: February 2007

Kennaway DJ, Hugel HM, Rowe SA. Characterization of the chicken brain melatonin‐binding protein using iodinated and triturated ligands. J. Pineal Res. 1994; 17: 137–148.AbstractThe melanoma‐binding protein in chicken brain membranes was characterized using both [125I]‐2‐iodomelatonin and [3H]‐melatonin as radioligands. Saturation studies conducted at 25°C revealed a single class of binding site with dissociation constants of 24 ± 4. 8 pM (n = 7) and 125 ± 21 pM (n = 6) for the iodinated and tritiated legends, respectively. Calculation of the affinity constant using data from kinetic experiments gave values of 2.2 ± 0.4 pM and 135 ± 15 pM for the iodinated and tritiated ligands, respectively. Competition studies showed that the rank order of inhibition of binding by melatonin analogues was similar for both radioligands (2‐iodomelatonin > melatonin > 2,3‐dihydromelatonin > N‐acetyl‐5‐methoxykynurenamine > N‐acetylserotonin > 5‐methoxytryptamine). The calculation of Ki, which depends upon the affinity constant, was 22 ± 4.9 pM and 129 ± 21 pM for 2‐iodomelatonin and melatonin, respectively, when the affinity constant derived from the [125I]‐2‐iodomelatonin saturation experiments was used, but 4.9 ± 1.5 pM and 33 ± 5.5 pM when the kinetically derived constant was used. When [3H]‐melatonin was used, the Ki for melatonin was 72 ± 8 pM and 20 ± 4.6 pM for 2‐iodomelatonin and melatonin. Binding of [125I]‐2‐iodomelatonin to the membranes was partially reversible at 25°C in contrast to the complete reversibility of [3H]‐melatonin. Examination of the effects of temperature on binding indicated that at 37°C both association and dissociation of both legends were accelerated. Closer examination showed that at 37°C there was a loss of approximately 40% of the [125I]‐2‐iodomelatonin binding sites and little influence upon the affinity of binding with time. By contrast, when [3H]‐melatonin was used, the affinity decreased fourfold, with only a slight change in the number of sites. If membranes were incubated at 37°C and then switched 25°C, binding increased, emphasizing the fact that the binding sites were not destroyed. Whereas there appears to be little doubt that 2‐iodomelatonin is a biologically active melatonin agonist, the binding of the radioactive form of this agonist to the putative melatonin receptor binding site is quite different from that of the endogenous ligand. This may have serious consequences in studies where receptor content is determined following physiological or pharmacological interventions.
Effects of single doses and daily melatonin treatments on serotonin metabolism in rat brain regions
Authors: Miguez J. M. , Martin F. J. , Aldegunde M. 
Published: February 2007

Miguez, JM, Martin F. J, Aldegunde M. Effects of single doses and daily melatonin treatments on serotonin metabolism in rat brain regions. J. Pineal Res. 1994; 17:170–176.AbstractThe acute effects of two doses (0. 5 and 1 mg/kg) of melatonin on the levels of tryptophan, serotonin, and 5‐hydroxyin‐doleacetic acid in several rat brain regions were studied. Tryptophan content in the brain regions was unchanged by the treatments. Melatonin at a dosage of 0. 5 mg/kg increased medial hypothalamic serotonin levels at 60 and 90 min after the injection. However, the dose of 1 mg/kg increased the levels of this amine or its metabolite in the preoptic area‐anterior hypothalamus, medial and posterior hypothalamus, amygdala, and midbrain. These results suggest a specific regional sensitivity to melatonin as well as a dose‐dependent response. The stimulatory melatonin effect on the serotoninergic system was also observed after a daily treatment with this hormone (0. 5 mg/kg, twice daily during 10 days) in both intact or pinealectomized rats. In intact rats, melatonin treatment increased the levels of 5‐hydroxyindole‐3‐acetic acid in the preoptic area‐anterior hypothalamus and medial hypothalamus, while in pinealectomized rats melatonin increased the serotonin content in the medial hypothalamic region. The data support the idea that melatonin has a selective action on serotonin metabolism in regions that contain serotoninergic terminals, especially at medial hypothalamic level.
Prolonged exposure of chicks to light or darkness differentially affects the quinpirole‐evoked suppression of serotonin N‐acetyltransferase activity in chick retina: An impact on dopamine D4‐like receptor
Authors: Zawilska Jolanta B. , Derbiszewska Teresa , Nowak Jerzy Z. 
Published: February 2007

Zawilska JB, Derbiszewska T, Nowak JZ. Prolonged exposure of chicks to light or darkness differentially affects the quinpirole‐evoked suppression of serotonin N‐acetyltransferase activity in chick retina. An impact on dopamine D4‐like receptor. J. Pineal Res. 1997; 22:59–64. © Munksgaard, CopenhagenAbstractDopamine plays an important role in regulation of melatonin biosynthesis in retinas of several vertebrate species. In the avian retina, the dopamine receptor that controls melatonin production represents a D4‐like subtype. Stimulation of this receptor by quinpirole (QNP) results in a dose‐dependent decline of the nighttime activity of serotonin N‐acetyltransferase (NAT, a key regulatory enzyme in melatonin biosynthesis) and melatonin level of the retina. The present study was undertaken to determine whether the ability of QNP to suppress nocturnal NAT activity of chick retina was affected by prolonged adaptation of animals to light and darkness. In the retina of chicks kept under a light:dark (LD) illumination cycle, dopamine and 3,4‐dihydroxyphenylacetic acid (DOPAC) levels measured at the end of the light phase were significantly higher than those found in the middle of the dark phase. In animals maintained under continuous light (LL) or darkness (DD) dopamine and DOPAC contents of the retina measured at these two time points were similar and resembled levels found during, respectively, the light and dark phase in the retina of chicks kept under LD illumination cycle. Adaptation of chicks to LL and DD resulted in an attenuated and enhanced, respectively, response of the retinal NAT activity to the suppressive action of QNP. When compared to the LD group, a parallel shift to the right (LL group) or left (DD group) of the dose‐response curve for QNP was observed, and the ED50 values for this dopamine receptor agonist were 3.4‐times higher (LL) or 2.8‐lower (DD) than those calculated for the control LD animals. It is suggested that prolonged exposure to light or darkness, by altering the level of the retinal dopaminergic neurotransmission, may modify the reactivity of the D4‐like dopamine receptors regulating NAT activity of the chick retina.
Effect of melatonin and corticosteroid on in vitro cellular immune function in humans
Authors: Rogers Naomi , van den Heuvel Cameron , Dawson Drew 
Published: February 2007

Rogers N, van den Heuvel C, Dawson D. Effect of melatonin and corticosteroid on in vitro cellular immune function in humans. J. Pineal Res. 1997; 22:75–80. © Munksgaard, Copenhagen.AbstractIt is well accepted that the immune system shows circadian rhythmicity and that circadian disruption can significantly alter indices of immune function. Recently, a functional link between the endocrine and immune systems has been proposed to explain circadian rhythms in immune activity. Of particular interest is the finding that hormones such as melatonin and corticosteroid are able to exert modulating effects on lymphocyte proliferation. Previous research examining the effects of melatonin in vitro, however, has produced equivocal results. The aim of this study, therefore, was to examine the effects of melatonin and corticosteroid, both separately and together, on mitogen‐stimulated human lymphocyte proliferation. Purified human lymphocytes were stimulated with concanavalin A (Con A, 4 μg/mL). Melatonin and/or corticosteroid were added to the culture medium during incubation. All cultures were done in quadruplicate. As expected, corticosteroid (25–1,000 ng/mL) significantly reduced proliferation by between 30 and 60% in a dose‐related manner (P<0.0001). Melatonin alone (10–1,000 fmol/mL) did not significantly affect lymphocyte proliferation. However, when lymphocytes were cultured in the presence of melatonin and corticosteroid, a significant decrease in proliferative function of 50–85% was observed (P<0.0001). Hence, the effect of melatonin and corticosteroid combined was significantly greater than that observed with corticosteroid alone (P<0.0001). Therefore, it appears that the in vitro effect of corticosteroid on immune function may be modulated by melatonin in physiological to pharmacological concentrations.
Pulsatile patterns of melatonin secretion in patients with gonadotropin‐releasing hormone deficiency: Effects of testosterone treatment
Authors: Luboshitzky R. , Herer P. , Lavie R 
Published: February 2007

Luboshitzky R, Herer P, Lavie P. Pulsatile patterns of melatonin secretion in patients with gonadotropin‐releasing hormone deficiency: Effects of testosterone treatment. J. Pineal Res. 1997; 22:95–101. © Munksgaard, Copenhagen.AbstractRecently, we have demonstrated that male patients with gonadotropin‐releasing hormone (GnRH) deficiency had increased nocturnal melatonin secretion that decreased to normal levels during testosterone treatment. The purpose of the current study was to examine if the abnormally increased melatonin levels in these patients were associated with pulsatile secretory patterns, and, if these were modified during testosterone administration. Characteristics of nocturnal melatonin and luteinizing hormone (LH) secretion were compared in six normal young males, six males with idiopathic hypogonadotropic hypogonadism (IGD), and in six males with constitutional delayed puberty (DP). Patients were examined in the untreated state and following the administration of 250 mg testosterone enanthate/month for 4 months. Serum samples for melatonin and LH levels were obtained every 15 min from 19.00 hr to 07.00 hr in a controlled light‐dark environment. Pulse detection and pulse characteristics were determined by the program ULTRA. In comparison with normal controls, untreated IGD patients showed significantly higher pulse frequency, lower relative increments and shorter half‐life times for melatonin. Similar findings were observed in DP patients, although statistically of borderline significance. Treatment with testosterone normalized melatonin pulse characteristics in both IGD and DP patients. The secretory pattern of LH release in these patients was characterized by significantly higher relative and absolute increments and shorter half‐life time without any significant change in the number of LH pulses. Taken together, these data suggest that melatonin is secreted in a pulsatile pattern in normal adult males and in male patients with GnRH deficiency. The abnormally increased nocturnal melatonin secretion observed in these patients may indicate that the pineal pulse generator is expressing an altered activity pattern within its normal capabilities. Testosterone administration normalized melatonin secretory patterns in IGD and DP patients. The lack of relationship between the pulsatile LH and melatonin secretory patterns suggest an independent signal for the nocturnal pulsatile melatonin and LH secretions.
Differential inhibitory effects of melatonin analogs and three naphthalenic ligands on 2‐[125I]iodomelatonin binding to chicken tissues
Authors: Pang Celia S. , Tang Pak L , Song Yong , Pang Shiu F. , Ng Kai W. , Guardiola‐Lemaitre Beatrice , Delagrange Philippe , Brown Gregory M. 
Published: February 2007

Pang CS, Tang PL, Song Y, Pang SF, Ng KW, Guardiola‐Lemaitre B, Delagrange P, Brown G.M. Differential inhibitory effects of melatonin analogs and three naphthalenic ligands on 2‐[l25I]iodomelatonin binding to chicken tissues. J. Peneal Res. 1997; 23:148–155. © Munksgaard, CopenhagenAbstractWe have compared the 50% inhibition values of 2‐[l25I]iodomelatonin ([125I]Mel) competition curves by melatonin and 3 naphthalenic ligands, N‐[2‐(7‐methoxy‐l‐naphthyl) ethyl] cyclobutane carboxamide (S20642), N‐propyl N‐[2‐(7‐methoxy‐l‐naphtyl) ethyl] urea (S20753), and N‐[2‐(7‐methoxy‐l‐naphthyl) ethyl] crotonamide (S20750), using membrane preparations of four tissues (lung, spleen, brain, and kidney) of the chicken simultaneously. In retired breeders, we have demonstrated that the affinities of S20642 were similar in the lung and spleen. However they were 2‐fold lower in the brain and 80‐fold lower in the kidney. Similar differential binding affinities to the melatonin receptors were observed in the four tissues of young male chicks. This suggests that age and sex have little influence on the differential inhibitory properties of melatonin and S20642 in the tissues studied. The addition of guanosine 5'‐0‐thiotriphosphate (GTPyS), which encouraged the uncoupling of melatonin receptor to the G protein complex, lowered the binding affinity of melatonin and S20642 in the tissues studied but their differentia] affinities in the four tissues were however maintained. The affinities of 5‐methoxy‐N‐cyclopropanoyltryptamine (CPMT) in the kidney were also 5–10‐fold lower than those in the lung, spleen, and brain of young male chicks. The distinctive differential affinities of melatonin, S20642, and CPMT for [l25I]Mel binding sites in the chicken lung, spleen, brain, and kidney indicated that the binding sites in these tissues are heterogeneous. Our study implicated that the naphthalenic ligand S20642 may be a useful melatonin analog to distinguish melatonin receptor subtypes in tissues and a possible drug candidate worthwhile for further investigations.
Creatinine is an appropriate reference for urinary sulphatoxymelatonin of laboratory animals and humans
Authors: Klante G. , Brinschwitz T. , Secci K. , Wollnik F. , Steinlechner S. 
Published: February 2007

Klante G, Brinschwitz T, Secci K, Wollnik F, Steinlechner S. Creatinine is an appropriate reference for urinary sulphatoxymelatonin of laboratory animals and humans. J. Pineal Res. 1997; 23:191–197. © Munksgaard, CopenhagenAbstractIn our studies on diurnal 6‐sulphatoxymelatonin (aMT6s) rhythms in various species, we have sometimes obtained fluctuating patterns. In most of these, the volume of individual urine fractions was not accurately measured because of methodological problems. Here, we report a simple method to overcome these problems by using urinary creatinine to estimate urine volume. The benefit of this method is demonstrated in two representative examples of the diurnal aMT6s rhythms of rats, domestic pigs and humans. Because the human urine fractions were collected accurately, the qualitative pattern of the aMT6s rhythm was not altered by using urinary creatinine as a substitute for urine volume. The total creatinine excretion (urine volume x creatinine concentration) was constant within a small range and showed no diurnal rhythm. In rats and pigs, the highly variable aMT6s concentrations relative to urine volume throughout the 24‐hr period were changed drastically by referring to creatinine. All aMT6s patterns became stable and qualitatively similar to those of the rest of the group. From these results it can be concluded that creatinine is an adequate substitute for urine volume and a beneficial parameter with which to overcome technical problems with urine collection from laboratory animals or unknown urine volumes in human studies.
Effects of sympathicolytic and sympathomimetic drugs on pineal ultrastructure in the domestic pig
Authors: Lewczuk Bogdan , Przybylska‐Gornowicz Barbara 
Published: February 2007

Lewczuk B, Przybylska‐Gornowicz B. Effects of sympathicolytic and sympathicomimetic drugs on pineal ultrastructure in the domestic pig. J. Pineal Res. 1997; 23:198–208. © Munksgaard, CopenhagenAbstractThe effects of a 4‐day administration of two sympathicolytic (α‐methyl‐p‐tyrosine, propranolol) and three sympathicomimetic (clorgyline, isoproterenol, dobutamine) drugs on the ultrastructure of the pineal gland in the domestic pig were examined. The morphological changes in the pinealocytes of the experimental groups mainly concerned cytoplasmic dense bodies, primary lysosomes, multivesicular bodies, dense core vesicles, and smooth endoplasmic reticulum. These structures seemed to be under direct or indirect control by the adrenergic nervous system. The relative volume of dense bodies in pinealocyte perikarya increased after administration of α‐methyl‐p‐tyrosine as well as propranolol and decreased on treatment with clorgyline. The decrease in the relative volume of primary lysosomes in pinealocyte perikarya was noted in pigs treated with clorgyline and isoproterenol. The number of multivesicular bodies in pinealocyte perikarya decreased after administration of α‐methyl‐p‐tyrosine. The numerical density of dense core vesicles in pinealocyte perikarya increased after treatment with clorgyline. Administration of isoproterenol and clorgyline resulted in the presence of wide cisterns of smooth endoplasmic reticulum. Narrow cisterns of this form of endoplasmic reticulum and lamellar whorls were observed after treatment with α‐methyl‐p‐tyrosine in pinealocytes with large dense bodies. The presence of multilamellar structures was a characteristic feature of the pinealocytes of pigs treated with isoproterenol and dobutamine. Administration of α‐methyl‐p‐tyrosine and clorgyline resulted in the appearance of pinealocytes which differed in number, size, and structure of dense bodies.
THE LETHALITY‐FOURIER NUMBER METHOD. HEATING RATE VARIATIONS AND LETHALITY CONFIDENCE INTERVALS FOR FORCED‐CONVECTION HEATED FOODS IN CONTAINERS
Authors: LENZ M.K. , LUND D.B. 
Published: February 2007

ABSTRACTHeat transfer and lethality in foods heated by force‐convection in agitated, reel‐type retorts (Steritort) were investigated. Equations describing the temperature profile at any position in the food were developed and experimentally verified for fluids and fluids with particles. For both types of food, the temperature profiles are a function of the heat transfer coefficient (h) at the inside surface of the container (the fluid container interface). For foods with particulate pieces, the temperature profiles, in both the fluid and the particle, are also a function of the heat transfer coefficient (hp) at the fluid particle interface. Empirical models are presented correlating both heat transfer coefficients (h or hp) with system parameters.Equations describing the temperature profile at the coldest point in the food (i.e. the point receiving least lethal treatment) were used in a modified form of the lethality‐Fourier number equation (Lenz and Lund 1977a) to calculate lethality. This method of calculating lethality agreed with lethalities calculated by the Improved General Method.Confidence intervals for lethality for forced‐convection heated products were determined using the Monte Carlo procedure described in Lenz and Lund (1977b). The 95% confidence intervals for the lethality ranged from 20–60% of the median value of the lethality depending on process conditions. The fluid/particle interface heat transfer coefficient (hp) had a significant effect on the lethality distributions.
AN APPROACH TO SOLVING THE OPTIMAL TEMPERATURE CONTROL PROBLEM FOR STERILIZATION OF CONDUCTION‐HEATING FOODS
Authors: HILDENBRAND P. 
Published: February 2007

ABSTRACTIn this paper, the optimal sterilization of canned solid foods is discussed. Such foods are influenced by heat conduction in the course of the thermal process. The way of optimizing the temperature control in this paper is to divide the total problem into two separate parts, namely into a process engineering and a control engineering optimization problem. It will be shown that this separation is admissable. With respect to the solution of the total problem, the results will be suboptimal.
MICROWAVE FREEZE DRYING
Authors: SUNDERLAND J. EDWARD 
Published: February 2007

ABSTRACTA critical review of recent work in microwave freeze drying of food products is presented. This is followed by a general evaluation and recommendation for future work. The major technical problems that would prevent commercial use of microwave freeze drying have been solved. Economic studies show that processing costs for microwave freeze drying are lower than the costs for conventional freeze drying. Thus there has been adequate research and development for commercialization. A discussion is presented for improving the transfer of technology to aid commercialization. Recommendations are made for additional research and development.
HEAT TRANSFER IN A VERTICAL, LIQUID‐FULL SCRAPED‐SURFACE HEAT EXCHANGER. APPLICATION OF THE PENETRATION THEORY AND WILSON PLOTS MODELS
Authors: CUEVAS ROBERT , CHERYAN MUNIR 
Published: February 2007

ABSTRACTHeat transfer characteristics of a scraped‐surface heat exchanger (Contherm Model 6 × 2) were evaluated at ultra high temperatures using water and soybean water extracts as model systems. The resistance equation was used to calculate internal (scraped‐side) heat transfer coefficients (hi) from the overall heat transfer coefficient, the wall coefficient and the external (steam‐side) coefficient (calculated from the Nusselt Theory using an iteration procedure). The Penetration Theory of Harriot (1958) predicted hi values quite well at low axial mass flow rates, where laminar flow conditions prevail. However, turbulent axial flow resulted in experimental higreater than predicted by the theory. A correction factor based on Prandtl number suggested by Trommelen et al. (1971) did not improve the prediction. The Wilson Plots method was useful for explicitly accounting for axial and rotational velocity effects, both of which significantly affected heat transfer, especially at high values of either variable.
THE EFFECT of AGE ON the GASTIGHTNESS of ISO FREIGHT CONTAINERS
Authors: SHARP A. K. , BANKS H. J. , IRVING A. R. 
Published: February 2007

ABSTRACTFor many transport applications, it is desirable to limit the interchange of gas between the atmospheres inside and outside a container. Such applications include the transport of produce prone to moisture uptake, incontainer fumigation and controlled‐ or modified‐atmosphere transport, either with or without refrigeration. In this study, the steady‐state pressure test was used to measure the gastightness of 143 containers with ages ranging up to eight years. the survey included general‐purpose containers of steel, glass‐fibre reinforced‐plywood and aluminum‐panel construction and bulk and refrigerated containers. Within each type of container, the gastightness varied over a wide range, but appeared to depend more on the type of construction than on age. the survey shows that well‐constructed containers can retain high levels of gastightness at ages of up to 8 years, and presumably throughout their service lives.